Seasonal change Research Papers - Academia.edu (original) (raw)

At-sea distributions of large scyphozoan jellyfish across the Irish Sea were studied using visual surface counts from ships of opportunity. Thirty-seven surveys were conducted along two[100 km long transects between Ireland and the UK... more

At-sea distributions of large scyphozoan jellyfish across the Irish Sea were studied using visual surface counts from ships of opportunity. Thirty-seven surveys were conducted along two[100 km long transects between Ireland and the UK from April to September in 2009 and 2010. Five species were recorded but only Aurelia aurita and Cyanea capillata were frequently observed. The first formal description of the seasonal changes in the abundances and distributions of these two species in the study area is provided. The highest densities of these species were more likely to be found *30 km offshore, but large aggregations were present both in coastal and offshore waters. Evidence for aggregations of medusae along physical discontinuities was provided by coupling jellyfish observations with simultaneous records of environmental parameters. The value of surveys from ships of opportunity as cost-effective semi-quantitative tools, to develop local knowledge on jellyfish abundance, distribution, and phenology is discussed.

In this paper, we have assessed the temporal, spatial and depth related variation of suspended particulate organic matter (POM) in the Bay of Bengal. For this purpose, suspended particulate matter (SPM) samples were collected from eight... more

In this paper, we have assessed the temporal, spatial and depth related variation of suspended particulate organic matter (POM) in the Bay of Bengal. For this purpose, suspended particulate matter (SPM) samples were collected from eight depths (2 to 1000 m) at 9 locations in the Bay of Bengal during July/August 2001 (Southwest monsoon, SWM), September/October 2002 (Fall Intermonsoon, FIM), and March/April 2003 (Spring Inter-monsoon, SPIM). The SPM samples were analyzed for chlorophyll a (Chl a), particulate organic carbon (POC) and total particulate nitrogen (TPN). The surface concentrations of POC varied from 4.3 to 11.1 µM C, 3.1 to 10.9 µM C, and 4.3 to 9.0 µM C during SWM, FIM, and SPIM, respectively. The levels of SPM, and the concentrations of Chl a, and POC were relatively higher in the offshore compared to the near shore stations, especially during SWM. The POC concentration and its contribution to the SPM were higher in the surface waters, and both decreased with increasing water column depth at most of the stations. The observed decrease with depth of POC indicates heterotrophic uptake and/or dilution by inorganic material, poor in POC. This was also reflected in the C/N ratio which generally increased with water column depth. The relatively low C/N and POC/Chl a ratios, and high Chl a and % POC during the SWM and FIM indicate the presence of relatively fresh POM in the Bay during these two seasons. The observed seasonal differences in the quality of POM appears to be governed by river runoff and the physical forces such as eddies which pump nutrients into the surface waters thereby enhancing biological production.

Urban dwellers experience conflicting thoughts and feelings about urban woodlands; valued for their natural qualities, the relief they provide from the stress of modern urban living and the opportunities they afford for children's play... more

Urban dwellers experience conflicting thoughts and feelings about urban woodlands; valued for their natural qualities, the relief they provide from the stress of modern urban living and the opportunities they afford for children's play and exploration. At the same time the seclusion inherent in this type of urban greenspace seems fraught with risk from crime, vandalism and abuse. Whilst many of these characteristics are well-researched, less is known about the differing perceptions of particular social groups. This study aimed to explore the ways in which age affects urban dwellers' aspirations, values and fears concerning the woods, and woodland accessibility, focusing on the views of elderly people (aged over 65). This pilot study was based in Norfolk Heritage Park, an urban park containing a variety of woodland settings located in Sheffield, UK. The questionnaire survey (participants n ¼ 97) revealed that although walking is the most popular leisure activity, most respondents did not visit urban parks as often as they would like, regardless of age. Whilst many of the meanings associated with urban woodland (were shared amongst age groups, it seemed that the elderly respondents particularly valued the woods for their links with the past, and opportunities for immersion in the natural world. Some respondents from all age groups had fears about their personal security in the woodland, and the concerns of the elderly were heightened by their perceived frailty, reduced mobility and sense of vulnerability; this age group had a corresponding need for particular measures to alleviate these problems. The study provides preliminary evidence for the idea that adults of different ages have differing perceptions and requirements in relation to urban woodlands. Due to the small sample size and other methodological issues, further research is needed to confirm and develop the findings.

Photosynthetic capacity, leaf nitrogen content, and stomatal conductance decreased with increasing leaf age in the chaparral shrub, Lepechinia calycina, growing in its natural habitat. Efficiency of resource use for three resources that... more

Photosynthetic capacity, leaf nitrogen content, and stomatal conductance decreased with increasing leaf age in the chaparral shrub, Lepechinia calycina, growing in its natural habitat. Efficiency of resource use for three resources that potentially limit photosynthesis did not, however, decrease with increasing leaf age. Light-use efficiency, given by the quantum yield of photosynthesis at low light intensities, was unaffected by leaf aging but decreased slightly through the winter and spring growing season. Water-use efficiency, the ratio of photosynthesis to transpiration at light saturation and with a constant water vapor concentration gradient, was not affected by leaf aging or seasonal change. Nitrogen-use efficiency, the ratio of photosynthesis at light saturation to leaf nitrogen content did not change with leaf age but was lower in the leaves with the highest specific weights. This ensemble of leaf-age effects is consistent with the hypothesis that aging represents resource redistribution and not uncontrolled deterioration.

Comparative chemical and botanical analyses of the reticulo-rumen content (RR) and the fill of the digestive system were carried out in free-living Norwegian reindeer {Rangifer t. tarandus) on South Georgia (SG) in summer (mean body mass... more

Comparative chemical and botanical analyses of the reticulo-rumen content (RR) and the fill of the digestive system were carried out in free-living Norwegian reindeer {Rangifer t. tarandus) on South Georgia (SG) in summer (mean body mass (BM) = 74 kg, n -10), and in northern Norway in late summer (NS) (mean BM = 77 kg, n = 6) and winter (NW) (mean BM = 60 kg, n = 11). The RR of SG reindeer contained mainly grasses, while grasses dominated in NS reindeer and woody plants and lichens in NW reindeer. Mean ruminal plant cell-wall contents (CWC) comprised 37% of organic dry matter (OM) in SG reindeer and 50 and 69% in NS and NW reindeer, respectively. The high CWC in NW reindeer was due to high intake of lichens containing as much as 45% hemi-cellulose. Mean ruminal content of lignin was as low as 5% of OM in SG reindeer, which was different (P < 0.05) from NS (14%) and NW reindeer (15%), respectively. The mean total gastro-inresrinal tract (GIT) (fill and tissue) weight was 27% of BM in SG reindeer, different (P < 0.05) from NS (18% of BM) and NW reindeer (22% of BM), respectively. Wet weight RR content was 14.5% of BM in SG reindeer, not different from NS (12.2% of BM) and NW reindeer (14.2% of BM). The ratio between the wet weight content of the distal fermentation chamber (DFC) and the RR wet weight content was 1:10 in SG reindeer, different (P < 0.05) from NS (1:14) and NW reindeer (1:14). We did not find any significant differences between the intestinal lengths of the groups investigated. It was concluded that the degree of fill of the different parts of GIT in reindeet seems to be related to the lignin content of plants eaten and not only of seasonal changes in appetite and availability of plants. Our data stress the fact that reindeer are highly adaptable to a wide range of different dietary plants, even in the southern hemisphere.

In order to evaluate the effects of contrasting hydrological scenarios on the spatial and temporal heterogeneity of phytoplankton in a reservoir, vertical chlorophyll and temperature profiles were measured and functional classification of... more

In order to evaluate the effects of contrasting hydrological scenarios on the spatial and temporal heterogeneity of phytoplankton in a reservoir, vertical chlorophyll and temperature profiles were measured and functional classification of phytoplankton was applied. From April to October 2007, at 1-2 week intervals, seasonal changes in various parameters were studied along the longitudinal axis of the canyon-shaped, eutrophic Ř ímov Reservoir (Czech Republic). At the river inflow, phytoplankton markedly differed from the rest of the reservoir, being dominated by functional groups D and J (pennate diatoms and chlorococcal algae) without a clear seasonal pattern. From April to mid-June, groups Y and P (large cryptophytes and colonial diatoms) prevailed in the whole reservoir. Phytoplankton spatial heterogeneity was the most apparent during the summer reflecting a pronounced gradient of environmental parameters from the river inflow to the dam (e.g., decreasing nutrients, increasing light availability, etc.). A dense cyanobacterial bloom (groups H1 and M) developed in the nutrient-rich transition zone, while functional Group N (desmids) dominated the phytoplankton at the same time at the dam area. In late summer, a sudden flood event considerably disrupted thermal stratification, altered nutrient and light availability, and later even resulted in cyanobacterial dominance in the whole reservoir. Additionally, our study emphasizes the importance of having an intensive phytoplankton monitoring program, which would allow for detecting severe consequences of sudden flood events on phytoplankton spatial and temporal heterogeneity, which significantly affect water quality at the dam area used for drinking water purposes.

Lessonia trabeculata is a brown seaweed inhabiting the rocky subtidal zone along the coast of central and northern Chile, where it is the dominant kelp, and an important species in community structure. Morphological and reproductive... more

Lessonia trabeculata is a brown seaweed inhabiting the rocky subtidal zone along the coast of central and northern Chile, where it is the dominant kelp, and an important species in community structure. Morphological and reproductive aspects of this alga are dependent on environmental conditions and geographic distribution, and the present study gives data on its reproductive periodicity. The reproductive phenology for three populations from northern Chile (29-30°S) was evaluated by means of seasonal examination of morphological and reproductive characteristics of both macroscopic sporophytes and microscopic gametophytes. Comparative laboratory cultures of spores were made to determine seasonal differences in their capacity to produce viable plants. This species is perennial, and demonstrates year-round presence of reproductive tissues, although showing variation in reproductive phenology over time and among populations. The size of blades increases in spring and summer, whereas its reproductive potential (e.g., area and proportion of the reproductive tissue and the release of spores) increases in autumn. Culture experiments showed that spring and summer reproductive tissue released zoospores which had low germination rates compared to those of autumn and winter, and which produced female gametophytes of low fertility. The population differences depended on the character analysed and the season of the year. The development of both phases of the life cycle of L. trabeculata may be influenced by the local environmental conditions and their seasonal changes, and were expressed as morphological and/ or reproductive changes in the plants. A better understanding of the seasonal adaptations may be obtained if future comparisons are made between widely separated populations or between individuals from the extremes of geographic distribution of the species.

To date, no other studies have examined the seasonal changes in circulating levels of various bile acids in the plasma of wild North American black bears, Ursus americanus. Using gas chromatography, bile acid concentrations were measured... more

To date, no other studies have examined the seasonal changes in circulating levels of various bile acids in the plasma of wild North American black bears, Ursus americanus. Using gas chromatography, bile acid concentrations were measured in plasma samples obtained during either early or late hibernation, and during summer active periods. Thus, specific compositional changes from individual animals were examined through a given year. Total bile acid concentrations in the plasma of these normal animals were found to range between 0.2 and 3.1 μmol/L (0.9 ± 0.2 μmol/ L, mean ± SEM). Cholic, ursodeoxycholic and chenodeoxycholic acids were the major bile acid species identified. Ursodeoxycholic acid represented 28.0 ± 2.6% of the total bile acid pool. Deoxycholic and lithocholic acids were found only in small amounts. In addition, total bile acid concentrations were lower in plasma samples obtained during hibernation compared with those obtained during summer active periods (0.6 ± 0.1 and 1.2 ± 0.4 μmol/L, respectively; p b 0.05). However, the relative proportion of ursodeoxycholic acid, was significantly greater in winter than in summer (31.5 ± 3.2% and 22.2 ± 4.5%, p b 0.05). Finally, taurine-conjugated bile acids were the predominant species in bear plasma, accounting for N 67% of the total bile acids. These data demonstrate that ursodeoxycholic acid is a major bile acid in black bear plasma, mostly conjugated with taurine. Further, the finding of seasonal variation in plasma bile acid composition provides evidence to support the possible role that ursodeoxycholic acid may play in cellular protection in hibernating black bears.

Foraging behaviour of wild coypu was studied to examine two hypotheses that had been previously proposed to explain the species' preference for aquatic plants. First, the nutritional benefit hypothesis which states that aquatic plants are... more

Foraging behaviour of wild coypu was studied to examine two hypotheses that had been previously proposed to explain the species' preference for aquatic plants. First, the nutritional benefit hypothesis which states that aquatic plants are more nutritional than terrestrial plants. Second, the behavioural trade-off hypothesis which states that coypus avoid foraging far from the water because of the costs associated with other types of behaviour. In order to test the nutritional benefit hypothesis, we studied the diet composition of coypus in relation to the protein content of the diet and of the plants available in the environment. Fieldwork was conducted seasonally from November 1999 to August 2000 at one study site located in the Province of Buenos Aires, east central Argentina. Behavioural observations showed that coypus remained foraging in the water and microhistological analysis of faeces indicated that their diet was principally composed of hygrophilic monocotyledons (Lemna spp. and Eleocharis spp.) throughout the year. We did not find support for the nutritional benefit hypothesis: nutritional quality (based on nitrogen content) of hygrophilic plants was not higher than that of terrestrial plants, and seasonal changes in diet quality did not match either fluctuations in vegetation quality or proportion of hygrophilic plants in the diet. Although not directly tested, the behavioural trade-off hypothesis may explain why coypus prefer to forage in or near the water as a mechanism for reducing predation risk. a We included the pteridophyte Azolla within the group of hygrophilic monocotyledons.

A climatological study of the spatial and temporal distribution of mean relative geostrophic vorticity over the Mediterranean region is examined for a period of 40 years (1958-1997). Two major cyclonic vorticity maxima are found in the... more

A climatological study of the spatial and temporal distribution of mean relative geostrophic vorticity over the Mediterranean region is examined for a period of 40 years (1958-1997). Two major cyclonic vorticity maxima are found in the Mediterranean at low levels, one covers the Gulf of Genoa and south Italy and the second is located over the southeastern Aegean Sea with different diurnal and seasonal characteristics, controlling cyclone formation. At upper levels, a large scale cyclonic vorticity zone covers the whole Mediterranean region with notably increased values at 300 hPa, being associated with jet stream dynamics, especially in the eastern Mediterranean. The seasonal changes of the horizontal vorticity distribution substantially reduce with height while the diurnal changes become unimportant at upper levels. Furthermore, the investigation of the vertical vorticity structure separately for the main cyclonic centres in the Mediterranean implies the different mechanisms that are responsible for cyclone formation in the western and eastern basin.

. Seasonal changes in the concentration of estrogens and testosterone in the plasma of the stallion. Anita. Reprod. Sci., A blood sample was taken from each of 15 stallions at monthly intervals for 14 consecutive months. Plasma... more

. Seasonal changes in the concentration of estrogens and testosterone in the plasma of the stallion. Anita. Reprod. Sci., A blood sample was taken from each of 15 stallions at monthly intervals for 14 consecutive months. Plasma concentrations of estrogens and testosterone were measured by radioimmunoassay methods. Estrogens in peripheral blood were present in much higher amounts than testosterone and were principally in a water-soluble, solvolyzable form (> 98%). The major component in the solvolyzed extracts behaved chromatographically as estrone. The mean plasma level (± S.E.) of estrogens averaged across months was 52.9 ± 4.5 ng m1-1. Individual stallions showed considerable month-to-month variation; for example, single monthly samples ranged from 29.5 to 160.6 ng m1-1 for the stallion with the highest single value. The highest mean monthly concentration was 69 ± ng m1-1 in May, and plasma levels were < 40 ng ml -~. during November and December. For the 11 Thoroughbred stallions in the study, the mean concentrations of estrogens were 73 -+ 5.8 ng m1-1 for May to July and 45 +-4.1 ng m1-1 for November to January (P > 0.001). The mean monthly concentrations (-+ S.E.) of testosterone ranged from 0.22 ± 0.05 to 0.90 ± 0.14 ng m1-1, and individual samples ranged from < 0.02 to 2.8 ng m1-1 of plasma. While the highest mean level of testosterone was seen in September, there was a significant difference (P < 0.01) between the values in the breeding season (May--July, 0.73 ± 0.07 ng m1-1 ) and the non-breeding season (November--January, 0.38 ± 0.08 ng ml -~). No marked seasonal changes were observed, however, in testosterone levels in several stallions. It was concluded that plasma estrogen levels may provide a more sensitive index of endocrine function of the testes in the stallion.

Ana Silvaa,b, Laura Quintanaa, Matıas Galeanoa & Pablo Errandoneaa aDepartamento de Neurofisiologıa, Instituto de Investigaciones Biológicas Clemente Estable; Unidad Asociada de Facultad de Ciencias, Universidad de la República, Avda.... more

Ana Silvaa,b, Laura Quintanaa, Matıas Galeanoa & Pablo Errandoneaa aDepartamento de Neurofisiologıa, Instituto de Investigaciones Biológicas Clemente Estable; Unidad Asociada de Facultad de Ciencias, Universidad de la República, Avda. Italia 3318, 11600 ...

We analysed 6 years (1997–2002) of continuous eddy covariance CO2 fluxes over a mixed temperate forest in the Belgian Campine region and present the long-term mean seasonal changes in net ecosystem exchange (NEE), gross primary production... more

We analysed 6 years (1997–2002) of continuous eddy covariance CO2 fluxes over a mixed temperate forest in the Belgian Campine region and present the long-term mean seasonal changes in net ecosystem exchange (NEE), gross primary production (GPP) and total ecosystem respiration (RE). Seasonal changes in NEE, GPP and RE were tightly correlated, with extremes in July and December/January. Nonetheless, maximum rates of RE slightly lagged behind the maximum rates of GPP. We observed a substantial increase in NEE at optimum light conditions (reduced uptake) above 24 °C. Because this increase is unlikely to be related only to the increase in RE, we hypothesize that it also indicates a significant decrease in GPP under dry and warm meteorological conditions. Because this increase in NEE was better correlated with atmospheric vapour pressure deficit than with temperature, we further hypothesize that the observed change in NEE was predominantly related to the effect of high atmospheric evapora...

Phenology shows sensitive responses to seasonal changes in atmospheric conditions. Forest understory phenology, in particular, is a crucial component of the forest ecosystem that interacts with meteorological factors, and ecosystem... more

Phenology shows sensitive responses to seasonal changes in atmospheric conditions. Forest understory phenology, in particular, is a crucial component of the forest ecosystem that interacts with meteorological factors, and ecosystem functions such as carbon exchange and nutrient cycling. Quantifying understory phenology is challenging due to the multiplicity of species and heterogeneous spatial distribution. The use of digital photography for assessing forest understory phenology was systematically tested in this study within a temperate forest during spring 2007. Five phenology metrics (phenometrics) were extracted from digital photos using three band algebra and two greenness percentage (image binarization) methods. Phenometrics were compared with a comprehensive suite of concurrent meteorological variables. Results show that greenness percentage cover approaches were relatively robust in capturing forest understory green-up. Derived spring phenology of understory plants responded to accumulated air temperature as anticipated, and with dayto-day changes strongly affected by estimated moisture availability. This study suggests that visible-light photo-graphic assessment is useful for efficient forest understory phenology monitoring and allows more comprehensive data collection in support of ecosystem/land surface models.

Seasonal variation in nutritional status among young children has been described in rural populations, but in few urban settings. We examined seasonality in 7 years of nutritional surveillance data from an urban shanty town near Lima,... more

Seasonal variation in nutritional status among young children has been described in rural populations, but in few urban settings. We examined seasonality in 7 years of nutritional surveillance data from an urban shanty town near Lima, Peru, where childen O-35 months old were measured at intervals of 45 months. We compared nutritional status by month, using generalized estimating equations to account for the intercorrelations among measurements of the same person at different times. The periodicity of the seasonal variation was found to fit a model in which the month of the year was sine-transformed, and this sinetransformed model was used to examine possible interactions with age? sex and year of examination. A total of 38 626 measurements was available from 11 333 children. In late winter, mean weight-for-height was an estimated 0.38 Z score higher than in late summer. The seasonal effect occurred at all ages, in both sexes, and in each year of surveillance. The amplitude was greatest for children 6-23 months old. The summer trough in weight-for-height was lower in 1989 than in other years; children who experienced this summer low had lower mean height-forage in subsequent years. The seasonal variation in nutritional status may be related to differences in dietary intake! or to the higher prevalence of bacterial diarrhoea in summer than in winter. The more marked drop in weight-for-height in 1989 and subsequent trough in height-forage may be related to political and economic changes than adversely affected food access in Peru.

Both top-down and bottom-up processes are common in terrestrial ecosystems, but how these opposing forces interact and vary over time is poorly understood. We tested the variation of these processes over seasonal time in a natural... more

Both top-down and bottom-up processes are common in terrestrial ecosystems, but how these opposing forces interact and vary over time is poorly understood. We tested the variation of these processes over seasonal time in a natural temperate zone grassland, a field site characterized by strong seasonal changes in abiotic and biotic conditions. Separate factorial experiments manipulating nutrients and cursorial spiders were performed in the wet and dry seasons. We also performed a water-addition experiment during the summer (dry season) to determine the degree of water limitation during this time. In the spring, nutrient addition increased plant growth and carnivore abundance, indicating a bottom-up control process. Among herbivores, sap-feeders were significantly enhanced while grazers significantly declined resulting in no net change in herbivore abundance. In the summer, water limitation was predominant increasing plants and all herbivores while nutrient (N) effects were non-significant. Top-down processes were present only in the spring season and only impacted the guild of grazing herbivores. These results show that bottom-up limitation is present throughout the season in this grassland, although the specific limiting resource changes as the season progresses. Bottom-up processes affected all trophic levels and many different guilds, while top-down effects were limited to a select group of herbivores and did not extend to the plant trophic level. Our results show that the relative strengths of top-down and bottom-up processes can shift over relatively short periods of time in habitats with a strong seasonal component.

Gracilaria cornea and G. crassissima are similar species that coexist at Bajo Pepito in the Mexican Caribbean. Differences in agar properties from both species were determined for two reproductive categories: carposporic and undetermined,... more

Gracilaria cornea and G. crassissima are similar species that coexist at Bajo Pepito in the Mexican Caribbean. Differences in agar properties from both species were determined for two reproductive categories: carposporic and undetermined, the latter mainly composed of tetrasporophytes. Agar yield (AY), agar gel strength (GS), 3,6-anhydrogalactose content (AG) and sulfate content (S) of native and alkali-treated agar were determined for both reproductive categories. Significant differences in native and alkali-treated agar between the reproductive categories were recorded for AY, GS and S from G. cornea and G. crassissima, as well as for AG of native agar from the latter species. Our results, and previous studies, demonstrate that neither reproductive stage was predominant over the other(s) in terms of having greater or lower values of agar properties. The potential economic use of agar differences from plants of different reproductive stage remains very limited. Lower AY and GS were...

As urbanized areas expand and develop throughout the world, the importance of understanding their effects on wildlife increases. Living in cities may be stressful for animals but may also provide benefits at the same time, and the sum of... more

As urbanized areas expand and develop throughout the world, the importance of understanding their effects on wildlife increases. Living in cities may be stressful for animals but may also provide benefits at the same time, and the sum of these effects should manifest in the body condition of individuals. Studies addressing this phenomenon tend to evaluate one or few indices of body condition, each of which may be subject to various confounding effects and seasonal changes. In this study we used multiple approaches to assess the effects of urbanization on adult body condition in house sparrows (Passer domesticus), a passerine undergoing population declines in urban habitats. In line with earlier studies, we found that sparrows in more urbanized habitats have reduced body mass. However, birds had similar scaled mass index (body mass corrected for body size) along the urbanization gradient at all times of the year, contradicting the previous result on type-1 regression residuals. In the non-breeding season, urban and rural birds had similar levels of corticosterone, hematocrit, and heterophil:lymphocyte ratio. In the molting season, hematocrit indicated better condition in rural birds whereas H:L ratio showed the opposite; however, these trends were not consistent between age groups. Two condition-dependent plumage traits, male bib size and wing bar size, showed no systematic variation along the gradient of urbanization. These results suggest that the environmental conditions experienced by adult house sparrows are not more stressful in more urbanized habitats, and they also highlight the importance of considering multiple indices of body condition.

The present study focused on the use of benthic invertebrate communities to assess the ecological quality of a Portuguese estuary characterized by strong seasonal changes and with eutrophication problems. Seasonal benthic samples were... more

The present study focused on the use of benthic invertebrate communities to assess the ecological quality of a Portuguese estuary characterized by strong seasonal changes and with eutrophication problems. Seasonal benthic samples were collected during a flood year and the methodology proposed by the WFD Portuguese group was used to classify benthic assemblages into five different quality classes. Factor analysis was applied to classify stations based on their physical-chemical status. Different classifications were obtained with different indices and among seasons and there was low agreement between indices and index-season interactions. Diversity indices were better correlated to eutrophication related variables than AMBI and ABC method. Predictable responses of benthic indices to anthropogenic stress symptoms were stronger during the dry period.

Although the last 200 years of colonisation has brought radical changes in economic and governance structures for thousands of Aboriginal and Torres Strait Islanders living in remote areas of northern Australia, many of these Indigenous... more

Although the last 200 years of colonisation has brought radical changes in economic and governance structures for thousands of Aboriginal and Torres Strait Islanders living in remote areas of northern Australia, many of these Indigenous people still rely upon, and live closely connected to, their natural environment. Over millennia, living 'on country', many of these communities have developed a sophisticated appreciation of their local ecosystems and the climatic patterns associated with the changes in them. Some of this knowledge is recorded in their oral history passed down through generations, documented in seasonal weather calendars in local languages and, to a limited degree, transcribed and translated into English. This knowledge is still highly valued by these communities today, as it is used to direct hunting, fishing and planting as well as to inform many seasonally dependant cultural events. In recent years, local observations have been recognised by non-Indigenous scientists as a vital source of environmental data where few historic records exist. Similar to the way that phenological observations in the UK and US provide baseline information on past climates, this paper suggests that Indigenous observations of seasonal change have the potential to fill gaps in climate data for tropical northern Australia, and could also serve to inform culturally appropriate adaptation strategies. One method of recording recent direct and indirect climate and weather observations for the Torres Strait Islands is documented in this paper to demonstrate the currency of local observations of climate and its variability. The paper concludes that a comprehensive, participatory programme to record Aboriginal and Torres Strait

European intertidal salt marshes are important nursery sites for juvenile fish and crustaceans. Due to the increasing threat of habitat loss, the seasonal changes of salt marsh fish communities need to be understood in order to appreciate... more

European intertidal salt marshes are important nursery sites for juvenile fish and crustaceans. Due to the increasing threat of habitat loss, the seasonal changes of salt marsh fish communities need to be understood in order to appreciate the ecological and economic importance of the saltmarsh habitat. This study was the first in Great Britain to investigate the seasonal changes of salt marsh fish communities and the variation in community structure between closely located marsh habitats. Between February 2007 and March 2008, five marshes on three estuaries of the Essex coastline were sampled using flume nets to block off intertidal creeks at high tide. Fourteen fish species were caught. The community overall was dominated by three species that made up 91.6% of the total catch: the common goby Pomatoschistus microps (46.2% of the total catch), juvenile herring Clupea harengus (24.3%), and juvenile and larval sea bass Dicentrarchus labrax (21.2%). Cluster analysis demonstrated clear seasonal patterns, with some community structures unique to specific marshes or estuaries. The marsh fish community shifts from a highly diverse community during spring, to a community dominated by D. labrax and P. microps in autumn, and low diversity during winter months. Gravimetric stomach content analysis of fish community identified three main trophic guilds; macroinvertivores, planktivores and omnivores. The macroinvertivore feeding guild contained D. labrax and P. microps, the two most frequently occurring species. This investigation demonstrates the importance of British salt marshes as nursery habitats for commercial fish species.

This work assessed the impacts of land-use patterns in the Ruvu river basin on water quality in the river system. Seasonal changes in water quality parameters were also investigated. Ten river water-sampling stations were selected and... more

This work assessed the impacts of land-use patterns in the Ruvu river basin on water quality in the river system. Seasonal changes in water quality parameters were also investigated. Ten river water-sampling stations were selected and samples were collected and analysed according to standard analytical procedures. The results showed that physico-chemical parameters of river water ranged as follows: pH, from 6.95 ± 0.09 to 8.07 ± 0.23; temperature, from 14.0 ± 0.06 to 31.1 ± 0.4°C; EC, from 39.8 ± 0.8 to 48,734 306 ls/ cm; TDS, from 19.9 ± 0.4 to 24,367 ± 152.9 mg/l; turbidity, from 3.0 ± 0.6 to 840 ± 69.3 NTU and DO, from 6.8 ± 0.02 to 16.78 mg/ l. The ranges for nutrient concentrations were NO 3 -N, from 0.006 ± 0.0003 to 0.62 ± 0.3 mg/l; NH 4 -N, from 0.34 ± 0.17 to 16.2 ± 0.5 mg/l; PO 4 -P, from 0.009 ± 0.001 to 1.75 ± 0.2 mg/l and TP, from 0.02 ± 0.003 to 3.56 ± 0.38 mg/l. Generally, water samples from stations with forested catchments had high levels of DO and low levels of NH 4 -N and NO 3 -N compared to those from farmland, industrial, residential and market places. There were clear seasonal variations showing an increase in the concentrations of nutrients during rainy season. The results show impairment of the water quality of the river by anthropogenic activities in the catchment. Water pollution prevention strategies to ensure prevention of pollution and protection of water resources in the Ruvu river watershed are recommended.

Forty-two species of waders, comprising 29 Palearctic migrants, eight residents, two partial migrants and three vagrants, were recorded in three years of monthly surveys of shorebirds in coastal Ghana. Eleven species occurred in... more

Forty-two species of waders, comprising 29 Palearctic migrants, eight residents, two partial migrants and three vagrants, were recorded in three years of monthly surveys of shorebirds in coastal Ghana. Eleven species occurred in internationally important populations: curlew sandpiper, little stint, sanderling, spotted redshank, greenshank, grey plover, ringed plover, black-winged stilt, avocet, black-tailed godwit and turnstone. Arrival of migrant waders in coastal Ghana began in August and reached a peak in November~December. Most waders left the Ghana coast in January, leaving only a small proportion which remained until final departure in April. Another peak in numbers was observed during the spring passage in some years for some wader species. The proportion of migrant wader populations oversummering on the Ghana coast varied with species, and from year to year. While the total populations of some species departed, as much as 30% of the populations of others remained on the Ghana sites during the northern summer. The wader numbers recorded in the different sites and the relative importance of the key sites showed annual fluctuations. Two sites, the Keta and Songaw Lagoons, qual([ied as internationally important wetlands in terms of their total wader numbers and by virtue of the fact that each supported internationally important populations of seven species of waders. Three other sites also supported internationally important populations: Sakumo Lagoon (4 species), Korle Lagoon (3) and Esiama (1). Two sites, Keta and Korle Lagoons, face immediate threat of coastal erosion and~or proposed developments involving drainage and land reclamation. The Sakumo and Songaw Lagoons have great potential for development as conservation areas and proposals have been submitted to this effect. 139 Biol. Conserv. 0006-3207/91/$03'50

Storage stability of oat groats processed commercially (conditioning with saturated steam followed by kiln drying) and with superheated steam (SS) was evaluated at room and elevated temperatures (21 and 38 C, respectively) for 26 and 13... more

Storage stability of oat groats processed commercially (conditioning with saturated steam followed by kiln drying) and with superheated steam (SS) was evaluated at room and elevated temperatures (21 and 38 C, respectively) for 26 and 13 weeks, respectively. Monitoring of hexanal and free fatty acid levels, moisture content, colour, and cold paste (64 C) viscosity, as well as sensory evaluation of groats were carried out during storage. Both the SS and the commercially processed groats remained shelf stable over the time periods tested. No substantial changes were noted in the colour, cold paste viscosity, and content of free fatty acids of differently heat processed groats as the storage time passed. Changes in the moisture content of stored groats reflected the seasonal changes in the humidity of the surroundings. At both storage temperatures, the amounts of hexanal released from groats processed either with SS or commercially increased with the increase of storage time. However, the groats processed with SS released lower amounts of hexanal than the groats processed commercially. As storage time progressed, both the SS and the commercially processed groats became blander, and it became increasingly difficult for sensory panellists to distinguish between groat samples from the different heat treatments.

Resumen Anteriores investigaciones, sugieren una incorporación por las plantas del carbono proveniente del metanol; por ello se diseñaron experimentos para determinar si su aplicación foliar afectaría el rendimiento y crecimiento en un... more

Resumen Anteriores investigaciones, sugieren una incorporación por las plantas del carbono proveniente del metanol; por ello se diseñaron experimentos para determinar si su aplicación foliar afectaría el rendimiento y crecimiento en un cultivo hidropónico de lechuga (Lactuca sativa L.). Se utilizó metanol a los porcentajes de 10, 20, 30, 40, 50, 60, 70 y 80, con un testigo sin tratamiento. Se midieron el peso fresco, longitud del tallo floral, apertura estomatal y se anotaron otras observaciones correspondientes. Hubo variaciones estacionales, probablemente debido a las diferentes tasas de crecimiento vegetativo y de almacenamiento a lo largo del año, originadas por cambios de temperatura y luminosidad. A la cosecha, se registraron incrementos de peso radicular con las aplicaciones foliares de metanol, pero no incrementos de peso foliar. También se pudo observar aumento en la elongación del tallo floral en los tratamientos con máximas aplicaciones de metanol. No se pudo comprobar efectos sobre la apertura estomatal.

Seasonal change in beach morphology is traditionally ascribed to a variation in the incident wave energy level with calm conditions in summer resulting in wide beaches with pronounced subaerial berms and energetic conditions in winter... more

Seasonal change in beach morphology is traditionally ascribed to a variation in the incident wave energy level with calm conditions in summer resulting in wide beaches with pronounced subaerial berms and energetic conditions in winter causing narrow beaches with nearshore bar morphology. The coastline of Perth, Western Australia, is characterised by a large seasonal variation in the incident wave height and local beaches exhibit a distinct seasonal change in morphology. However, these morphological changes are better explained by a seasonal reversal in the littoral drift direction than by variations in the incident wave energy conditions. In summer, when northward sediment transport prevails due to sea breeze activity, beaches located south of coastal structures, headlands or rocky outcrops become wider due to the accumulation of sediment against the obstacle. These beaches will subsequently erode in winter during storms when the longshore sediment transport is toward the south. In contrast, beaches located north of obstacles will become narrower during summer and wider during winter. The usefulness of the dimensionless fall velocity (where Hb is the breaker height, ws is the sediment fall velocity and T is the wave period) as a predictor of presence/absence of bar morphology and beach type was investigated. It was found that Ω fluctuates around the threshold of bar formation (Ω≈1.5–2) over a variety of time scales (daily, weekly, and seasonally). These temporal variations in Ω in conjunction with the relatively low wave energy level that characterises the coast negates the development of beach and nearshore morphology that is in equilibrium with the hydrodynamic conditions. As a result, bar occurrence and beach type can not be readily predicted using Ω along the Perth coast.

This paper presents the design and implementation of a vision-based navigation and landing algorithm for an autonomous helicopter. The vision system allows to define target areas from a high resolution aerial or satellite image to... more

This paper presents the design and implementation of a vision-based navigation and landing algorithm for an autonomous helicopter. The vision system allows to define target areas from a high resolution aerial or satellite image to determine the waypoints of the navigation trajectory or the landing area. The helicopter is required to navigate from an initial position to a final position in a partially known environment using GPS and vision, to locate a landing target (a helipad of a known shape or a natural landmark) and to land on it. The vision system, using a feature-based image matching algorithm, finds the area and gives feedbacks to the control system for autonomous landing. Vision is used for accurate target detection, recognition and tracking. The helicopter updates its landing target parameters owing to vision and uses an on board behavior-based controller to follow a path to the landing site. Results show the appropriateness of the vision-based approach that does not require any artificial landmark (e.g., helipad) and is quite robust to occlusions, light variations and seasonal changes (e.g., brown or green leaves).

Polar seaweeds are strongly adapted to the low temperatures of their environment, Antarctic species more strongly than Arctic species due to the longer cold water history of the Antarctic region. By reason of the strong isolation of the... more

Polar seaweeds are strongly adapted to the low temperatures of their environment, Antarctic species more strongly than Arctic species due to the longer cold water history of the Antarctic region. By reason of the strong isolation of the Southern Ocean the Antarctic marine flora is characterized by a high degree of endemism, whereas in the Arctic only few endemic species have been found so far. All polar species are strongly shade adapted and their phenology is finely tuned to the strong seasonal changes of the light conditions. The paper summarises the present knowledge of seaweeds from both polar regions with regard to the following topics: the history of seaweed research in polar regions; the environment of seaweeds in polar waters; biodiversity, biogeographical relationships and vertical distribution of Arctic and Antarctic seaweeds; life histories and physiological thallus anatomy; temperature demands and geographical distribution; light demands and depth zonation; the effect of salinity, temperature and desiccation on supraand eulittoral seaweeds; seasonality of reproduction and the physiological characteristics of C. Wiencke (&) AE U. H. Lü der microscopic developmental stages; seasonal growth and photosynthesis; elemental and nutritional contents and chemical and physical defences against herbivory. We present evidence to show that specific characteristics and adaptations in polar seaweeds help to explain their ecological success under environmentally extreme conditions. In conclusion, as a perspective and guide for future research we draw attention to many remaining gaps in knowledge.

Whole-life costing and residual service-life prediction of structures require quantitative information on cover-zone properties and threshold values for corrosion initiation and, once initiated, the rate of corrosion. It is clear that... more

Whole-life costing and residual service-life prediction of structures require quantitative information on cover-zone properties and threshold values for corrosion initiation and, once initiated, the rate of corrosion. It is clear that there exists a need to determine those near-surface characteristics of concrete, which promote the ingress of gases and liquids containing dissolved contaminants. In addition, in-situ monitoring of the seasonal change in such properties could assist in making realistic predictions as to the in-service performance of the structure, likely deterioration rates for a particular exposure condition, or compliance with the specified design life. To this end, this paper presents a review of sensors and associated monitoring systems from which information concerning corrosion activity, concrete (electrical) resistivity, oxygen availability, carbonation and chloride ingress can be obtained at strategic locations within a structure. This paper is based upon a draft of a RILEM Technical Recommendation 'Measurements with embedded sensors' prepared for RILEM Technical Committee TC-154 'Electrochemical methods for measuring metallic corrosion in concrete'. The work also formed part of the European research programme COST 521 -'The Corrosion of Steel in Reinforced Concrete Structures'.

Within the framework of the international research project MELMARINA, seasonal dynamics of plankton communities in three North African coastal lagoons (Merja Zerga, Ghar El Melh, and Lake Manzala) were investigated. The sampling period... more

Within the framework of the international research project MELMARINA, seasonal dynamics of plankton communities in three North African coastal lagoons (Merja Zerga, Ghar El Melh, and Lake Manzala) were investigated. The sampling period extended from July 2003 to September 2004 with the aim of evaluating hydrological and other influences on the structure, composition and space-time development of these communities in each lagoon. Phytoplankton in Merja Zerga showed a quasi-permanent predominance of marine diatoms in the open sea station and in the marine inlet channel. Dinoflagellates were abundant in summer and early autumn in the marine inlet and extended into the central lagoon station. In Ghar El Melh, marine species (especially diatoms and dinoflagellates) dominated despite occasional winter inflows of freshwater. In Lake Manzala, freshwater species generally predominated and the planktonic communities were comparatively very diverse. Chlorophyceae contributed 39% of the total species recorded and diatoms and cyanophyceans were also common; the Dinophyceae, Euglenophyceae, Chrysophyceae and Cryptophyceae less so. Zooplankton communities in both Ghar El Melh and Merja Zerga were dominated by marine copepods. Rotifera, Copepoda, Ostracoda, and Cladocera were recorded in both lagoons as were meroplanktonic larvae of Polychaeta, Cirripedia, Mysidacea and Gastropoda and free living nematodes. Ghar El Melh was the more productive of these two lagoons with spring and early summer being the productive seasons. Zooplankton communities in Lake Manzala were generally dominated by rotifers and highest zooplankton abundances occurred in April (2003). Sampling stations near the marine inlets showed the highest diversity and the zooplankton communities showed considerable spatial variation within this large lagoon. The three lagoons represent very different water bodies contrasted strongly in terms of tidal effects and freshwater availability. Yet, there are some similarities in ecosystem structure. Space-time development of the plankton communities was similar especially in Merja Zerga and Ghar El Melh. Species abundances and specific diversities indicated that seasonal changes in salinity and nutrient concentrations were the main influential factors. Lake Manzala was the most productive lagoon and all the three sites supported toxic algal species. Relatively low plankton biomass in Merja Zerga and Ghar El Melh probably resulted from a combination of factors including highly episodic nutrient inputs, light suppression (by turbidity) and nutrient competition with benthic algae. Water quality variables were largely driven by the hydrological regime specific to each lagoon. Nutrient enrichment and, particularly for Lake Manzala, sea level rise threaten the sustainability of the planktonic ecosystems in all three lagoons.

We radio-tracked fifteen reproductive females (5 pregnant, 5 lactating, 5 in post-lactation) of the Daubenton’s bat in summer 2005 in order to reveal the effect of reproductive state on their foraging and roosting activity. Spatial... more

We radio-tracked fifteen reproductive females (5 pregnant, 5 lactating, 5 in post-lactation) of the Daubenton’s bat in summer 2005 in order to reveal the effect of reproductive state on their foraging and roosting activity. Spatial activity of females decreased from pregnancy to lactation and increased again in the post-lactation period. Overall time spent foraging did not differ among the three study periods. However, while pregnant and lactating females spent similar proportion of the night length foraging, females in the post-lactation period were foraging for shorter part of night. The frequency of nightly visits to roosts was highest during lactation but there was a trend towards shortening of particular visits during that period. All but one roost were in tree hollows excavated by woodpeckers in spatially restricted area of ca 0.7 km2. Tree cavities used during pregnancy were located higher on a tree trunk and had larger entrance area than the cavities used in the two later periods. Bats switched roosts every 2–3 days (range 1–8) and moved to a new roost up to 800 m apart. Pregnant females tended to switch roosts more frequently than females in the two later periods. We did not observe a significant effect of minimum nightly temperature on the activity of radio-tracked Daubenton’s bats. Therefore, we suggest that observed seasonal changes in the pattern of behaviour of Daubenton’s bat females were driven by their changing energetic demands rather than by some extrinsic factors (e.g. weather conditions).

The obligation to ensure adequate potable water supply to everyone, has necessitated the development of groundwater resources for reliable rural water supply in most developing countries. An understanding of spatial variation and... more

The obligation to ensure adequate potable water supply to everyone, has necessitated the development of groundwater resources for reliable rural water supply in most developing countries. An understanding of spatial variation and processes affecting water quality is essential in sustaining usable water supplies under changing climate and local environmental pressures. In this study, an assessment of quality and dominant hydro-geochemical processes affecting the quality of groundwater from weathered basement aquifers in Mzimba district, Northern Malawi, has been conducted. Groundwater samples were collected from 172 hand-pumped boreholes, drilled for domestic rural water supply and analysed for major and minor ions, pH and total dissolved solids (TDS). In general, groundwater is of low mineralisation (TDS range: 29-1896 mg L À1 for the dry season), with hydro-geochemical facies dominated by Ca-HCO 3 , which evolves to Ca-Cl water type. Multivariate statistical analysis (HCA and PCA) and geochemical interpretation showed that the Ca-HCO 3 groundwater type result from hydrolysis of silicate minerals, which causes the solution to reach equilibrium with kaolinite. The processes of cation exchange of Na + and K + in the groundwater for Ca 2+ and Mg 2+ on clay minerals, carbonate precipitation and evaporation, are shown to modify the chemical composition from Ca-HCO 3 types to Ca-Cl types. Groundwater is generally of good quality in both rainy and dry seasons, with little seasonal changes. The United States Salinity Laboratory Staff and Wilcox diagrams showed that most samples were also suitable for irrigation except for 4% (eight samples) of the groundwater samples (with EC > 2000 lS cm À1 ). These are located in alluviums and colluviums localised near river banks and in inter hill valleys.

The waters dominating the Brazilian Continental Shelf to the south of Santa Marta Cape (28 40 0 S) are marked by their strong interannual variability. Both the seasonal oscillation of the Brazil-Malvinas (Falkland) Confluence (BMC) region... more

The waters dominating the Brazilian Continental Shelf to the south of Santa Marta Cape (28 40 0 S) are marked by their strong interannual variability. Both the seasonal oscillation of the Brazil-Malvinas (Falkland) Confluence (BMC) region and the seasonal variations of the La Plata River and Patos Lagoon outflows are reflected in the seasonal changes of the vertical and horizontal water mass structure in the Southern Brazilian Shelf. In the region to the north of Santa Marta Cape, the shelf is mainly described in the literature as dominated by Tropical Waters (TW) transported southwards by the Brazil Current (BC). However, the first Lagrangian (buoy) measurements made on the inner Brazilian shelf have shown that a coastal current flowing in the opposite direction in relation to the BC occurred on the shelf as far north as 24 S during the 1993 austral autumn and winter. Recent papers have suggested that the arrival at low latitudes of cold waters originating in the BMC region is an anomalous phenomenon and that it can be either forced by local winds during wintertime or related to the ENSO. High-resolution sea surface temperature (SST) imagery and the Lagrangian measurements taken in 1993 and 1994 are used in this paper to describe the temperatures, velocity, energy and oscillations present in this coastal current. These two data sets show that the current is not only fed by waters of Subantarctic or coastal origin but also receives a contribution of TW at the surface by lateral mixing. By analysing a set of monthly averaged SST images from 1982 to 1995, this work suggests that the intrusion of cold waters transported by the coastal current can be a regular winter phenomenon occurring on the Brazilian shelf at latitudes up to the vicinity of 25 S. Given its consistency, this current is named here the Brazilian Coastal Current. r

Buffaloes play a prominent role in rural livestock production, particularly in Asia. Reproduc-Ž . tive efficiency is the primary factor affecting productivity and is hampered in female buffalo by i Ž . Ž . inherent late maturity, ii poor... more

Buffaloes play a prominent role in rural livestock production, particularly in Asia. Reproduc-Ž . tive efficiency is the primary factor affecting productivity and is hampered in female buffalo by i Ž . Ž . inherent late maturity, ii poor estrus expression in summer, iii distinct seasonal reproductive Ž . patterns, and iv prolonged intercalving intervals. Ovarian function is central to these issues; hence, the focal point of this review is ovarian function in Bubalus bubalis, particularly, in relation to seasonal changes. Ovarian anatomy, follicular and luteal development development, and hormonal profiles during the estrous cycle are discussed. Review of the literature revealed a paucity of critically derived information on follicular and ovulatory patterns in buffalo, particularly, in relation to seasonal estrusrbirthing. Efforts may be directed at understanding the process Ž . Ž recruitment, development, atresia and temporal pattern follicle selection, dominance, subordi-. nate follicle suppression, follicle numbers, and, preovulatory changes of follicular dynamics using techniques which permit serial assessment of changes occurring over time. Emphasis may be directed towards investigating follicular ''waves'' as a functional unit, rather than the estrous cycle, in the context of whole animal endocrinology. The data obtained from such basic studies may then be used to develop and test models for enhancing reproductive efficiency. q

1] We investigate temporal variations in the polarization of surface waves determined using ambient seismic noise cross-correlations between station pairs at the time of the Mw 6.0 Parkfield earthquake of September 28, 2004. We use data... more

1] We investigate temporal variations in the polarization of surface waves determined using ambient seismic noise cross-correlations between station pairs at the time of the Mw 6.0 Parkfield earthquake of September 28, 2004. We use data recorded by the High Resolution Seismic Network's 3-component seismometers located along the San Andreas Fault. Our results show strong variations in azimuthal surface wave polarizations, Y, for the paths containing station VARB, one of the closest stations to the San Andreas Fault, synchronous with the Parkfield earthquake. Concerning the other station pair, only smooth temporal variations of Y are observed. Two principal contributions to these changes in Y are identified and separated. They are: (1) slow and weak variations due to seasonal changes in the incident direction of seismic noise; and (2) strong and rapid rotations synchronous with the Parkfield earthquake for paths containing station VARB. Strong shifts in Y are interpreted in terms of changes in crack-induced anisotropy due to the co-seismic rotation of the stress field. Because these changes are only observed on paths containing station VARB, the anisotropic layer responsible for the changes is most likely localized around VARB in the shallow crust. These results suggest that the polarization of surface waves may be very sensitive to changes in the orientations of distributed cracks and that implementation of our technique on a routine basis may prove useful for monitoring stress changes deep within seismogenic zones.

A dynamical model for simulating growth of the brown macroalga Saccharina latissima is described. In addition to wet and dry weights, the model simulates carbon and nitrogen reserves, with variable C/N ratio. In effect, the model can be... more

A dynamical model for simulating growth of the brown macroalga Saccharina latissima is described. In addition to wet and dry weights, the model simulates carbon and nitrogen reserves, with variable C/N ratio. In effect, the model can be used to emulate seasonal changes in growth and composition of the alga. Simulation results based on published, environmental field data are presented and compared with corresponding data on growth and composition. The model resolves seasonal growth, carbon and nitrogen content well, and may contribute to the understanding of how seasonal growth in S. latissima depends simultaneously on a combination of several environmental factors: light, nutrients, temperature and water motion. The model is applied to aquaculture problems such as estimating the nutrient scavenging potential of S. latissima and estimating the potential of this kelp species as a raw material for bioenergy production.

The Lower Toarcian Posidonia Shale is famous for its excellently preserved fossils and its high amount of organic matter (up to 16%). Both quality of preservation and accumulation of organic matter have been explained by permanent anoxic... more

The Lower Toarcian Posidonia Shale is famous for its excellently preserved fossils and its high amount of organic matter (up to 16%). Both quality of preservation and accumulation of organic matter have been explained by permanent anoxic bottom water conditions. High-resolution geochemical, sedimentological and palaeoecological investigations of various sections of the Posidonia Shale in SW-Germany, however, indicate that oxygen availability was variable and ranged from short oxygenated periods to longer-term anoxia. The benthic macrofauna consists of nine fossil communities and was used, in combination with geochemical data, to reconstruct a time-averaged oxygen curve. Anoxic conditions prevailed during the deposition of the Toarcian black shales; they were, however, punctuated by various short periods (weeks to years) with oxygenated bottom water conditions. Sedimentological (e.g. distinctiveness of microlamination, siliciclastic content) and geochemical parameters (e.g. organic matter content, isotopic signatures: δ18O and δ13C, molecular redox parameters: pristane/phytane ratio, arylisoprenoids) exhibit a remarkable covariation and seem to be controlled by sea level fluctuations. Maximum oxygen depletion and an extreme negative shift of δ13Corg values (−34‰) occurred during the early falciferum-zone. This is explained by the recycling of 12C-enriched carbon derived from remineralization of organic matter on and within the substrate during low sea level stand and a highly elevated redox boundary including photic zone anoxia. The subsequent transgression permitted enhanced water exchange with the Tethyan Ocean and caused improvement of living conditions at the end of the falciferum-zone.Other important factors controlling the depositional environment are the overall palaeogeographic situation and climate. The early Jurassic is the latest period before break-up of Pangaea and probably was ruled by a strong meridional atmospheric circulation system with pronounced seasonal changes of prevailing trade- and monsoon-wind systems. An estuarine circulation with a positive water balance and surface water with slightly reduced salinity in the summer alternated with an anti-estuarine circulation and a negative water balance in the winter. During the summer months a stratified water column with anoxic conditions below the halocline developed. δ18O data indicate low salinity in the surface water during the monsoon-influenced summer. High productivity was then located in the photic zone and the corresponding isotopically light δ18O-signal was fixed in the calcareous nannoplankton. During the winter months a saline circulation system brought oxygen to the benthic environment, favouring temporary benthic colonization, especially during times of relative sea level high stand.

Sampel permukaan yang di ambil dari 4 transet (50 stesen persampelan) di hutan paya bakau Setiu dianalisa ciri-ciri sedimen. Ciri-ciri sedimen di kawasan kajian menunjukkan perubahan yang signifikan (P<0.05) terhadap musim. Saiz sedimen... more

Sampel permukaan yang di ambil dari 4 transet (50 stesen persampelan) di hutan paya bakau Setiu dianalisa ciri-ciri sedimen. Ciri-ciri sedimen di kawasan kajian menunjukkan perubahan yang signifikan (P<0.05) terhadap musim. Saiz sedimen (Ø) didapati meningkat pada musim monsun dan sebaliknya ketika musim bukan monsun. Dalam kajian ini, 230 Th ekses digunakan bagi menentukan kadar pengenapan dan sebanyak 0.61 cmthn -1 telah diperolehi. Sekiranya kadar pengenapan yang diperolehi diambil kira, hutan paya bakau di Setiu berkemungkinan berada dalam peringkat belum matang dengan anggaran usia lebih kurang 163 tahun.

This work presents the results of a combined study on the beach morphology and the evolution at short- and medium-term of the littoral between Ceuta and Cabo Negro (Morocco). It is an interesting sector showing a great increase of human... more

This work presents the results of a combined study on the beach morphology and the evolution at short- and medium-term of the littoral between Ceuta and Cabo Negro (Morocco). It is an interesting sector showing a great increase of human occupation and coastal structures. The monitoring program allowed for the reconstruction of the beach morphological behavior and the seasonal changes. The studied beaches presented reflective profiles recording little seasonality, with the most notable morphological changes being strictly related to storms. Surf Similarity and Surf Scaling parameters highlighted the existence of intermediate and reflective beach states, characterized by plunging breakers. Aerial photographs and a satellite image have been geo-referenced and elaborated with GIS tools to reconstruct the short- and medium-term evolution of the littoral and the sediment transport pathways. The littoral showed important erosion at short- and medium-term related to a negative sedimentary budget because of offshore transport. Sand accumulation was recorded close to the main ports, i.e., Marina Smir and Marina Kabila. These port structures constituted impermeable, fixed limits, which divided the studied area into littoral cells. Other free, transit limits were also observed.

Seasonal changes in the microphytoplankton assemblages were examined in the coastal zone of Bozcaada Island with regard to some major physical and chemical variables. Samples were collected from May 2000 to December 2001 at four stations.... more

Seasonal changes in the microphytoplankton assemblages were examined in the coastal zone of Bozcaada Island with regard to some major physical and chemical variables. Samples were collected from May 2000 to December 2001 at four stations. A total of 108 dinoflagellates, 102 diatoms, 1 chrysophycean, 3 dictyochophycean, and 1 prasinophycean species were identified and quantified during the study period. Diatoms and dinoflagellates were the most important in terms of species number and abundance. The maximum values of total microphytoplankton were observed at 0.5 m depth (46.2 × 103 cells l−1 at st. 3) in May as this was the month when the diatom Pseudo-nitzschia pungens bloomed. Chlorophyll (chl) a concentration ranged between 0.08 (August) and 0.78 μg l−1 (February). May was another important month in which chlorophyll a increased (0.41–0.47 μg l−1). Species diversity values (H′log2) ranged from 1.66 bits (June, 20 m) to 4.11 bits (November, 0.5 m). The increase was attributed to a more balanced distribution of abundance among species. The amounts of nitrate + nitrite (0.6−3.7 μg-at N l−1), phosphate (0.2−0.6 μg-at P l−1) and silicate (0.7−2.5 μg-at Si l−1) were recorded on each sampling occasion. Nutrient concentrations and chl a values of the research area were found to be poorer than those of the many other coastal areas in the northeastern Mediterranean. The mean atomic ratio of nitrogen to phosphorus varied from 1.3 (June) to 12.9 (February). This ratio was lower than the Redfield ratio of 16 for ocean phytoplankton, and phytoplankton was potentially limited by nitrogen for most of the months. The result of this study confirms and emphasizes the oligotrophic nature of the eastern Mediterranean.

The aim of this investigation was to develop and validate a new method to predict time to exhaustion (pTE) from blood lactate variables measured during a submaximal non-exhaustive constant workload cycling test in professional cyclists. A... more

The aim of this investigation was to develop and validate a new method to predict time to exhaustion (pTE) from blood lactate variables measured during a submaximal non-exhaustive constant workload cycling test in professional cyclists. A multiple regression equation to estimate pTE from blood lactate variables measured within the first 10 min of a submaximal test and TE was determined in 40 competitive cyclists. Predicted TE reliability [individual coefficient of variation (CV)] was calculated in eight amateur cyclists who repeated the proposed test three times. Seasonal variations of pTE were monitored in 12 professional cyclists. Validity of pTE was determined by the known-group difference method in 49 professional cyclists. The prediction equation was: log n TE = 4.2067 À 0.8221(log n B) À 0.2519(log n C), where B is the lactate concentration at the 10th minute of the constant workload test and C is the lactate slope calculated between the 5th and 10th minute (adjusted r 2 =0.83, root mean square error in cross validation=23.1%). Predicted TE CV was 11.7%. The pTE obtained at the beginning of the season and the best and worst tests performed during the competitive season, resulted 162, 224 and 103% higher than the basic period test, respectively (P<0.05). Predicted TE was the only parameter discriminating elite from subelite professional cyclists. In conclusion, this study demonstrates that pTE is a valid and practical alternative to incremental tests and direct measures of endurance capacity requiring exhaustive efforts for the evaluation of competitive cyclists.

Seasonal changes in vegetative growth, leaf gas exchanges, carbon isotope discrimination (D) and carbohydrate status were monitored in de-fruited coffee trees (Coffea arabica L.) grown in the field, from October 1998 through September... more

Seasonal changes in vegetative growth, leaf gas exchanges, carbon isotope discrimination (D) and carbohydrate status were monitored in de-fruited coffee trees (Coffea arabica L.) grown in the field, from October 1998 through September 1999, in Viçosa (20845 0 S, 42815 0 W, 650 m a.s.l.), southeastern Brazil. Of the total growth over the 12-month study period, 78% occurred in the warm, rainy season (October-March), and 22% during the cool, dry season (April-September). Throughout the active growth period, the rate of net carbon assimilation (A) averaged 8.6 mmol m À2 s À1 , against 3.4 mmol m À2 s À1 during the period of reduced growth. In the active period, growth, unlike A or D, was strongly negatively correlated with air temperature. In contrast, growth and A were both correlated positively, and D correlated negatively, with air temperature during the reduced growth period. However, the depressions of A and growth might have simply run in parallel, without any causal relationship. Changes in A appeared to be largely due to stomatal limitations in the active growing season, with non-stomatal ones prevailing in the slow growth period. Foliar carbohydrates seemed not to have contributed appreciably to changes in growth rates and photosynthesis. #

The rapid galvanostatic pulse technique was applied on site on a large number of measuring points with reinforcement varying from severely corroding to passive state. The measurements provide reliable results on corrosion potential, ohmic... more

The rapid galvanostatic pulse technique was applied on site on a large number of measuring points with reinforcement varying from severely corroding to passive state. The measurements provide reliable results on corrosion potential, ohmic resistance and polarization resistance in very short time. The overall scatter of the data is not bigger than with any other instrumentation used for corrosion rate determination in the field. For actively corroding zones the current from the counter electrode is self-confined, no guard-ring is needed and the corrosion rate can be calculated on the basis of the reinforcement area under the counter-electrode. For passive zones the calculated “corrosion rate” is overestimated (on a very low level). Corrosion rate calculated from polarization resistance data are always instantaneous values. For engineering application (residual service life) the daily and seasonal changes in corrosion rate have to be considered. In the frequent case of chloride induced localized corrosion the local penetration rates calculated from Rp data can vary up to a factor of 5–10 and local penetration rates of 1 mm/year may occur. This uncertainty on a very high level of corrosion rate is much more important than variations induced by using devices with or without guard ring.