Estuary Research Papers - Academia.edu (original) (raw)

To enable a relevant interpretation of otolith strontium : calcium (Sr/Ca) variations in terms of habitat shifts of eels, the Sr/Ca-salinity relationship in eel otoliths was validated. Downstream and upstream migrations of young eels were... more

To enable a relevant interpretation of otolith strontium : calcium (Sr/Ca) variations in terms of habitat shifts of eels, the Sr/Ca-salinity relationship in eel otoliths was validated. Downstream and upstream migrations of young eels were reproduced in the laboratory by transferring groups of fish every 2 months between aquaria filled with water coming from the Dordogne river (salinity = 0), the upper Gironde estuary (salinity = 5), the lower Gironde estuary (salinity = 25) and the coast (salinity = 30), which represented the salinity gradient observed in the Gironde-Garonne-Dordogne watershed. Ontogenetic changes in otolith Sr/Ca were assessed in two groups of control fish that were kept in one of either two constant salinities (fresh water or seawater). X-ray electron microprobe (wavelength dispersive spectrometry, WDS) analyses of Sr/Ca ratios in the otoliths showed that the change of aquarium was recorded as a Sr/Ca increase (downstream migration) or a Sr/Ca decrease (upstream migration). No ontogenetic effect was detected in otoliths of control fish outside glass eel marks in either group of fish. The electron microprobe (WDS) analysis of the Sr/Ca life (transected in several otoliths of eels caught in the Gironde-Garonne-Dordogne watershed) showed that some of them were migrant eels that had experienced one major habitat shift during their continental life.

This paper reviews research that has taken place on physical oceanography and sedimentology on New Zealand's estuaries and the inner shelf since c. 1967. It includes estuarine sedimentation, tidal inlets, beach morphodynamics, nearshore... more

This paper reviews research that has taken place on physical oceanography and sedimentology on New Zealand's estuaries and the inner shelf since c. 1967. It includes estuarine sedimentation, tidal inlets, beach morphodynamics, nearshore and inner shelf sedimentation, tides and coastal currents, numerical modelling, short-period waves, tsunamis, and storm surges. An extensive reference list covering both published and unpublished material is included. Formal teaching and research programmes dealing with coastal landforms and the processes that shape them were only introduced to New Zealand M91078

Aquatic coastal systems are affected by high fluctuations in salinity and the zooplankton may rely on dispersal or dormancy to recolonise these environments. Here, we analysed the long-term dynamics of the zooplankton community over 6... more

Aquatic coastal systems are affected by high fluctuations in salinity and the zooplankton may rely on dispersal or dormancy to recolonise these environments. Here, we analysed the long-term dynamics of the zooplankton community over 6 years during large salinity fluctuations in a coastal lagoon (Garças Lagoon, Brazil) and the effect of salinity on the hatching patterns of the resting egg bank. We hypothesised that salinity is the main driving factor of the zooplankton community structure, and that increases in salinity reduce the species richness and the abundance of hatchlings. Multiple regression analysis showed that salinity was associated negatively with species richness in the open water, whereas total phosphorus and chlorophyll-a concentrations were negatively and positively related to abundance respectively. Redundancy analysis demonstrated that temporally structured environmental variables (total phosphorus and salinity) were important for zooplankton composition. Periods of...

This study investigated the behaviour of Pomacea bridgesii, describing the daily activity, substrate selection and the influence of the flood regime in the Amazon, the species’ native habitat. The present study described the daily... more

This study investigated the behaviour of Pomacea bridgesii, describing the daily activity, substrate selection and the influence of the flood regime in the Amazon, the species’ native habitat. The present study described the daily activity and substrate selection, and evaluated the activity adaptations of the gastropods in a simulated flood-pulse regime. Gastropods were collected in Amazonas, Brazil, in June 2013. Assessments of the daily behaviour, substrate selection, and flood-pulse simulation were made in experimental water tanks. The snails were observed hourly for 48h, and their behaviour recorded on an ethogram. The snails were more active during the night, when up to 80% of them moved about. In general, during both day and night, the gastropods used the pebble substrate most often. Comparing the day periods, a significant proportion of the individuals that were using the pebbles moved to other substrates (t=5; d.f.=2; P=0.03). The interaction of the behaviour of P. bridgesii...

Inputs of fresh water and grazing both can control aquatic food webs, but little is known about the relative strengths of and interactions between these controls. We use longterm data on the food web of the freshwater Hudson River estuary... more

Inputs of fresh water and grazing both can control aquatic food webs, but little is known about the relative strengths of and interactions between these controls. We use longterm data on the food web of the freshwater Hudson River estuary to investigate the importance of, and interactions between, inputs of fresh water and grazing by the invasive zebra mussel (Dreissena polymorpha). Both freshwater inputs and zebra mussel grazing have strong, pervasive effects on the Hudson River food web. High flow tended to reduce population size in most parts of the food web. High grazing also reduced populations in the planktonic food web, but increased populations in the littoral food web, probably as a result of increases in water clarity. The influences of flow and zebra mussel grazing were roughly equal (i.e., within a factor of 2) for many variables over the period of our study. Zebra mussel grazing made phytoplankton less sensitive to freshwater inputs, but water clarity and the littoral food web more sensitive to freshwater inputs, showing that interactions between these two controlling factors can be strong and varied.

This study examined the concentrations of Escherichia coli in soil and water samples, and some physicochemical properties of water collected from the Karnafuly River estuary, Bangladesh during March-June 2012. Among the water parameters,... more

This study examined the concentrations of Escherichia coli in soil and water samples, and some physicochemical properties of water collected from the Karnafuly River estuary, Bangladesh during March-June 2012. Among the water parameters, temperature was in the range 26.5 to 32°C, salinity varied between 0 and 5 ppt, pH values ranged from 7.5 to 7.9 and dissolved oxygen (DO) was recorded at concentrations of 2.28 to 2.91 mg/l. The average total E. coli were 26 cells/ml in water, but the sediment contained 96.42 cells/g of E. coli. The population of E. coli was always higher in sediment than those that occurred in water among all sampling stations. The growth of E. coli were positively correlated (P < 0.01) with water temperature and negatively correlated with salinity, pH and DO. The data on water quality parameters and occurrence of E. coli indicated that water of the Karnafuly estuary is polluted and unhygienic for drinking, even impossible to use for washing purposes without any treatment.

Identifying the respective role of environmental, landscape and management factors in explaining the patterns in community composition is an important goal in ecology. Using a set of 32 temporary ponds in northern Morocco we studied the... more

Identifying the respective role of environmental, landscape and management factors in explaining the patterns in community composition is an important goal in ecology. Using a set of 32 temporary ponds in northern Morocco we studied the respective importance of local (within the pond) and regional (density of ponds in landscape) factors and the impacts of different land uses on the plant species assemblages, separating pond and terrestrial species. The main hypotheses tested were that (1) species assemblages respond to both local and regional environmental factors, (2) anthropogenic pressure has a negative influence on the number of pond species, and that (3) human activities differ in their impact on pond biodiversity. The results showed that (1) local factors explain most of the variation in plant community composition, and (2) land use impacts the communities through changing local environmental conditions, leading to a loss of typical pond species. Aside from recreation, all oth...

Parasites constitute the majority of coral reef animal diversity and are believed to contribute significantly to host, community and trophic dynamics. Anilocra spp. are large conspicuous ectoparasitic isopods, making them ideal models for... more

Parasites constitute the majority of coral reef animal diversity and are believed to contribute significantly to host, community and trophic dynamics. Anilocra spp. are large conspicuous ectoparasitic isopods, making them ideal models for host–parasite studies. In the tropical western Atlantic and Caribbean, Anilocra haemuli infects the ecologically important French grunt (Haemulon flavolineatum). French grunt are trophic connectors between reef and seagrass environments, and how A. haemuli infection influences connectivity is unknown. As a first step in understanding the French grunt–A. haemuli association, we conducted reef surveys during three consecutive years to quantify the abundance and prevalence of infected fish on reef sites in the north-eastern Caribbean. We examined their correlations with fish population and aggregation size, and social affiliation. Annual infected fish abundance and prevalence per site ranged from 0–24 fish and 0–66%. Prevalence: (1) appeared autocorre...

Estuaries represent highly dynamic environments, especially with respect to salinity. Exploitation of these habitats by marine species can assist their ecological success, however they require specialized behavioral strategies as well as... more

Estuaries represent highly dynamic environments, especially with respect to salinity. Exploitation of these habitats by marine species can assist their ecological success, however they require specialized behavioral strategies as well as physiological abilities to cope with the fluctuations of physical stressors. The Valdivia River estuary, southern Chile, is a site of high larval recruitment and juvenile abundance of the commercial crab species Cancer edwardsii, particularly during the spring and summer months. This estuary experiences severe low salinity events (b7.5) for periods exceeding 6 h, that are associated with rainfall events and the subsequent higher flow rates of the tributaries. To determine the strategies employed by juvenile crabs living in the inner portions of the estuary in the face of changes in salinity conditions, we evaluated their survival and behavioral responses when exposed to a salinity gradient. Early juveniles were incubated at salinities of 0, 7.5, 15-22.5, 32 and crab mortality was recorded after 1, 6 and 12 h of exposure. In addition, early juveniles were experimentally exposed to continuous and gradual changes in saline conditions to evaluate their behavior, which was recorded on video. The main results were (1) despite most Cancer species being considered weak osmoregulators, 30% of individuals of C. edwardsii were able to survive freshwater conditions for 12 h. (2) burying and not quiescence behavior was associated with a drop in salinity, (3) in severe hyposaline conditions, the crabs increased their survival burying in the substrate, probably using higher salinity (N 22) interstitial water. Our findings suggest that burying behavior plays a key role in allowing the crabs inhabit inner estuarine areas where sudden and unexpected severe hyposalinity events occur.

Resource limitation controls the base of food webs in many aquatic ecosystems. In coastal ecosystems, nitrogen (N) has been found to be the predominant limiting factor for primary producers. Due to the important role nitrogen plays in... more

Resource limitation controls the base of food webs in many aquatic ecosystems. In coastal ecosystems, nitrogen (N) has been found to be the predominant limiting factor for primary producers. Due to the important role nitrogen plays in determining ecosystem function, understanding the processes that modulate its availability is critical. Shallow-water estuarine systems are highly heterogeneous. In temperate estuaries, multiple habitat types can exist in close proximity to one another, their distribution controlled primarily by physical energy, tidal elevation and geomorphology. Distinctions between these habitats such as rates of primary productivity and sediment characteristics likely affect material processing. We used membrane inlet mass spectrometry to measure changes in N 2 flux (referred to here as denitrification) in multiple shallow-water estuarine habitats through an annual cycle. We found significantly higher rates of denitrification (DNF) in structured habitats such as sub...

The study of benthic ecology within European estuaries is discussed. The history of estuarine science, and the definition of an estuary is briefly reviewed. Estuarine benthic ecology is considered with regard to its geographical, economic... more

The study of benthic ecology within European estuaries is discussed. The history of estuarine science, and the definition of an estuary is briefly reviewed. Estuarine benthic ecology is considered with regard to its geographical, economic and political context. It is shown that much recent study has been motivated by attempts to clean up estuaries, which were polluted after decades, or even centuries of pollution. Much has been achieved in the control of pollution, and many estuaries show clear signs of recovery. Particular focus has been on the estuaries entering the North Sea, with the realization that it is not the North Sea that is polluted, but its estuaries. The scientific appraisal of the benthos of estuaries has been particularly assisted by the ecosystem approach, which has both aided our understanding of their function as well as answering some of the questions posed by the impact of mankind. The European Union is identified as a powerful factor in benthic ecology, either through legislation or through the encouragement of collaborative programs, some of which have been particularly important in identifying common factors across a wide geographical spread of estuaries. It is concluded that in general estuaries have got cleaner, but that many problems remain, ranging from eutrophication through to sea-level change. The future of estuarine benthic ecology lies in meeting the new challenges.

Intertidal animals display a suite of cyclic behaviours that evolved as adaptations to the predictable cycle of inundation and exposure. In estuarine habitats, mud snails from the genus Hydrobia are among the most abundant grazers, and... more

Intertidal animals display a suite of cyclic behaviours that evolved as adaptations to the predictable cycle of inundation and exposure. In estuarine habitats, mud snails from the genus Hydrobia are among the most abundant grazers, and have received considerable attention with respect to the behavioural mechanisms mediating locomotion, dispersal, and feeding, although the nature of the control of these processes has remained elusive. In particular, it is not clear whether endogenous activity patterns are related to periodic changes of microphytobenthos biomass at the sediment surface, or whether they are timed to the tidal cycle at all. In the present study, we address the crawling activity of Hydrobia ulvae under constant conditions, as well as the effects of individual size and previous short-term exposure to tides of different range, by recording immersed individual snails under constant dark conditions. We show that the species displays an overt circatidal pattern of crawling, with activity peaks around high water, and that the start of inundation may act as an entrainment agent of the rhythm. Moreover, the results obtained indicate that smaller snails display higher levels of activity, although neither the size nor previous in situ influence of tidal range has an effect on the period and on the amplitude of the rhythm. These findings suggest that fluctuations of microphytobenthos biomass are not a sufficiently strong selective pressure to have shaped locomotor activity in H. ulvae. Moreover, feeding of H. ulvae should take place mostly during high water and be independent of periodic fluctuations of microphytobenthos biomass at the surface of the sediment.

Population parameters are necessary in order to understand the health of any fishery to determine appropriate management measures. The prawn Macrobrachium equidens is an important component of the artisanal Macrobrachium fishery of the... more

Population parameters are necessary in order to understand the health of any fishery to determine appropriate management measures. The prawn Macrobrachium equidens is an important component of the artisanal Macrobrachium fishery of the Cross River Estuary, contributing about 3.8 and 2.9% by number and weight, respectively, to the total catch of the multi-species Macrobrachium fishery of the area. Growth and mortality parameters of this prawn Macrobrachium equidens was studied from length-frequency data using ELEFAN Programme of FAO-ICLARM Stock Assessment Tools (FiSAT), and the following results were obtained: asymptotic length (L ∞ ) = 107.12 mm, growth constant K = 1.25/year, oscillation constant C = 1, Winter Point WP = 0.35, total mortality (Z) = 4.97/year, natural mortality (M) = 2.69/year, fishing mortality (F) = 2.28/year and exploitation rate (E) = 0.46. The fishery is on the verge of over-exploitation. Regulatory management measure to improve the contributions of this fishery to the overall prawn landing in the area is imperative. The most realizable management option is the closed period, during the reproductive season. This implies periodic closures at two alternate moon phases during the peak of reproductive activities. This option eliminates the contentious closure of the fishery during the most 'lucrative fishing season'. The fisherfolk will easily adopt these short closure periods and cooperate to ensure sustainable management.

vegetation change. Several hypotheses are advanced to explain this occurrence, including increases in The landward transgression of manrainfall, revegetation of areas cleared for groves into saltmarsh environments in the estuaries... more

vegetation change. Several hypotheses are advanced to explain this occurrence, including increases in The landward transgression of manrainfall, revegetation of areas cleared for groves into saltmarsh environments in the estuaries agriculture, altered tidal regimes or estuary water of south-east Australia over the last five decades is levels, and increases in nutrient levels and established as a widespread trend through a review sedimentation. of a number of independent studies. This process is occurring in a range of geomorphic settings, and

. Inductively coupled plasma atomic emission spectrophotometry ICP-AES was used to determine heavy metal concentrations in the shells and soft tissues of the periwinkle Littorina littorea, collected at seven sites along the Scheldt... more

. Inductively coupled plasma atomic emission spectrophotometry ICP-AES was used to determine heavy metal concentrations in the shells and soft tissues of the periwinkle Littorina littorea, collected at seven sites along the Scheldt estuary. Several metals accumulate in the animals soft body parts, and are related to the seawards decreasing pollution gradient. No clear correlation with a previously detected shell size patterning could be established. ᮊ

The present water quality of the Humber rivers and coastal zone depends on a complex interplay of factors, including physical ones, such as the underlying geology, which influences soil type, climatic ones, such as the rainfall, which... more

The present water quality of the Humber rivers and coastal zone depends on a complex interplay of factors, including physical ones, such as the underlying geology, which influences soil type, climatic ones, such as the rainfall, which influences runoff, socio-economic ones, which influence present-day human activities in the catchment, and the legacy of former activities, such as contaminated sediments from mining. All of these factors affect the fluxes of nutrients and other contaminants to the rivers and coastal zone. The Water Framework Directive (WFD) requires the production of a river basin management plan intended to lead to the achievement of good chemical and ecological status for all water bodies in the catchment over the next two decades. This paper provides an overview of the current environmental and socio-economic state of the Humber catchment and coastal zone, and broadly examines how socio-economic drivers affect the fluxes of nutrients and contaminants to the coastal zone, using the driverpressure-state-impact-response (DPSIR) approach. This is followed by an overview of future research, describing the use of scenarios to simulate future fluxes and provide a consistent framework to evaluate potential policies to improve water quality in the estuary. The Humber catchment is one of eight case studies within a European research project, EUROCAT (EVK1- CT-2000-00044), which aims to achieve integrated catchment and coastal zone management by analysing the response of the coastal sea to changes in fluxes of nutrients and contaminants from the catchments. For the Humber case study, the research focuses on the fluxes of two nutrient elements, N and P, and four metal contaminants, As, Cu, Pb and Zn. The project requires the integration of scientific and socio-economic approaches, bringing together quantitative environmental data garnered for individual river catchments and coastal zones in previous research programmes, and local and regional socio-economic data, to aid decision-makers in their search for integrated and sustainable coastal zone management strategies. ᮊ

Fluorescence-based observations provide useful, sensitive information concerning the nature and distribution of colored dissolved organic matter (CDOM) in coastal and freshwater environments. The excitation -emission matrix (EEM)... more

Fluorescence-based observations provide useful, sensitive information concerning the nature and distribution of colored dissolved organic matter (CDOM) in coastal and freshwater environments. The excitation -emission matrix (EEM) technique has become widely used for evaluating sources and sinks of CDOM. Water scattering peaks, however, can create problems for quantitative analysis and display of the EEMs, especially for samples with low CDOM concentrations. Here we report a new method for eliminating Rayleigh and Raman scatter peaks from EEMs during post-processing of the data in MATLABR. An algorithm was developed to excise scatter peaks (i.e. peak emission F 10 -15 nm at each excitation wavelength) from the scan data and replace the excised values using three-dimensional interpolation of the remaining data (Delaunay triangulation method). The interpolated surface was constrained to pass through the non-excised values so that only data in excised portions were replaced. Tests of the algorithm in non-scatter regions indicate expected deviations of 0 -4% for interpolated regions of DOM fluorescence peaks (i.e. difference between measured and interpolated intensity after removal/interpolation), which is within machine error for the primary observations. This new scattering correction method is shown to provide much improved results in the quantitative analysis of EEMs compared to the conventional blanksubtraction procedure. The method is used to process EEMs and fluorescence quantum yields for water samples obtained along a salinity transect in a river located on the coast of the southeastern United States. Results of this analysis demonstrate observed shifts in EEM peak positions along most of the transect cannot be accounted for by a simple model that computes EEMs as a function of salinity assuming that the dominant driver of EEM spectral change is mixing between riverine and marine waters within the estuary. Other results show that fluorescence apparent quantum yields (AQYs) increased with increasing salinity and pH in the estuary and that the highest quantum yields are observed on excitation by 350 -380-nm light. Modeling results and the observed EEM spectral changes indicate that photoreactions had an important effect on the fluorescent dissolved organic matter (FDOM) optical properties in the estuary. The increase in fluorescence quantum yields with increasing salinity and pH in the estuary likely were caused by reactions involving magnesium or hydroxide ions that reduced fluorescence quenching by chelated iron and possibly other paramagnetic ions. The results of the study indicate that 0304-4203/$ -see front matter D Marine Chemistry 89 (2004) 15 -36 EEM analysis with careful scatter correction can provide a powerful tool for evaluating pathways for carbon cycling in estuaries. D

Collection of marine invertebrates for use as fishing bait is a substantial activity in many parts of the world, often with unknown ecological consequences. As new fisheries develop, it is critical for environmental managers to have high... more

Collection of marine invertebrates for use as fishing bait is a substantial activity in many parts of the world, often with unknown ecological consequences. As new fisheries develop, it is critical for environmental managers to have high quality ecological information regarding the potential impacts, in order to develop sound management strategies. Crab-tiling is a largely unregulated and un-researched fishery, which operates commercially in the south-west UK. The target species is the green crab Carcinus maenas. Those crabs which are pre-ecdysis and have a carapace width greater than 40 mm are collected to be sold to recreational anglers as bait. Collection involves laying artificial structures on intertidal sandflats and mudflats in estuaries. Crabs use these structures as refugia and are collected during low tide. However, the effect that this fishery has on populations of C. maenas is not known. The impact of crab-tiling on C. maenas population structure was determined by sampling crabs from tiled estuaries and non-tiled estuaries using baited drop-nets. A spatially and temporarily replicated, balanced design was used to compare crab abundance, sizes and sex ratios between estuaries. Typically, fisheries are associated with a reduction in the abundance of the target species. Crab-tiling, however, significantly increased C. maenas abundance. This was thought to be a result of the extra habitat in tiled estuaries, which probably provides protection from natural predators, such as birds and fish. Although crabs were more abundant in tiled estuaries than non-tiled estuaries, the overall percentage of reproductively active crabs in non-tiled estuaries was greater than in tiled estuaries. As with most exploited fisheries stocks, crabs in exploited (tiled) estuaries tended to be smaller, with a modal carapace width of 20-29 mm rather than 30-39 mm in non-tiled estuaries. The sex ratio of crabs however; was not significantly different between tiled and non-tiled estuaries. These results illustrate the potential to manage fished populations using habitat provision to mitigate the effects of fishing pressure.

Anthropogenic climate change is already apparent and will have significant, ongoing impacts on Australian fishes and their habitats. Even with immediate actions to reduce greenhouse gases, there will be sustained environmental changes.... more

Anthropogenic climate change is already apparent and will have significant, ongoing impacts on Australian fishes and their habitats. Even with immediate actions to reduce greenhouse gases, there will be sustained environmental changes. Therefore, it is necessary to consider appropriate adaptations to minimise detrimental impacts for both fishes and the human populations that utilise them. Climate change will have a range of direct effects on the physiology, fitness, and survivorship of Australia's marine, estuarine and freshwater fishes, but also indirect effects via habitat degradation and changes to ecosystems. Effects will differ across populations, species and ecosystems, with some impacts being complex and causing unexpected outcomes. The range of adaptation options and necessary levels of intervention to maintain populations and ecosystem function will largely depend on the vulnerability of species and habitats. Climate change will also have an impact on people who depend on fishes for food or livelihoods; adapting to a new climate regime will mean trade-offs between biological assets and socioeconomic drivers. Models can be used to help predict trends and set priorities; however, they must be based on the best available science and data, and include fisheries, environmental, socioeconomic and political layers to support management actions for adaptation.

The analysis of age structure of fisher women showed that 35-55 years age groups are mainly engaged in various fishery related activities (50%) in average of total population. The average family size is 6, and 51.5% being the illiterate... more

The analysis of age structure of fisher women showed that 35-55 years age groups are mainly engaged in various
fishery related activities (50%) in average of total population. The average family size is 6, and 51.5% being the illiterate
group. About 15% of the population are migrant having immigration from Bangladesh. Undernutrition and malnutrition
are quite prevalent among the fisherwomen. The fisher women earn more than fifty percent (58%) of their livelihood
from fisheries and related activities. Mass media exposure and extension contact of the fisher women both in freshwater
and marine stretch was very low. Most of the fisherwomen perceive (81%) that lack of credit facilities from the Banks,
Co-operatives etc is the major constraint. In most of the cases fisherwomen are not aware of the facilities offered by the
State and Central Governments. Launching of mass literacy campaigns particularly for fisherwomen are much needed.
Formation of SHGs, Mahila Mandal to upgrade their knowledge and skill is suggested.

The present study documents three facies associations recorded from the Patherwa Formation. These facies are related to tidally influenced fluvial channel (Facies association A), tidal channel (Facies association B) and tidal sand... more

The present study documents three facies associations recorded from the Patherwa Formation. These facies are related to tidally influenced fluvial channel (Facies association A), tidal channel (Facies association B) and tidal sand bar/tidal flat sandy facies (Facies association C). The spatio-temporal variation of these facies associations and palaeocurrent trends suggest tide dominated estuarine system. The estuaries were operational along a 60 km long NW-SE trending palaeo-shoreline. The Patherwa Formation grades up-section into facies packages of increasing tidal energy and terminate with the deposition within the upper flow regime estuarine settings.

Trends of annual sea level records of four tidal observatories of the Hugli estuary—Sagar, Gangra, Haldia, and Diamond Harbour—are analysed from the records of Permanent Service for Mean Sea Level (PSMSL). The rates of sea level changes... more

Trends of annual sea level records of four tidal observatories of the Hugli estuary—Sagar, Gangra, Haldia, and Diamond Harbour—are analysed from the records of Permanent Service for Mean Sea Level (PSMSL). The rates of sea level changes for the stations are found to be –3.82, +0.89, +2.43 and +4.85 mm yr^–1 respectively, connoting a significant positive relation between landward distances of the stations and the rates of sea level rise. This seems to be mainly controlled by disequilibrium in the morphological state of the landward-narrowing estuary with some contribution from sediment autocompaction. Sea level trends of the Hugli have no apparent relation with erosion and accretion of its tidal islands.

Their application to the interpretation of analogous outcrop and subsurface depositional systems This prolifically illustrated atlas is the outcome of an outstanding 'town and gown' cooperation between the Norwegian oil company, Statoil,... more

Their application to the interpretation of analogous outcrop and subsurface depositional systems This prolifically illustrated atlas is the outcome of an outstanding 'town and gown' cooperation between the Norwegian oil company, Statoil, and the Faculty of Geosciences at Utrecht University in the Netherlands. Recognizing the present focus on sedimentary sequences rather than the diagnostics of sedimentary structures, the authors help to redress the imbalance by providing a comprehensive overview of characteristic sedimentary structures formed in recent inshore tidal environments and in tidally-influenced river channels subject to microtidal to mesotidal conditions. The work also establishes the basis for seamlessly transferring information from modern depositional systems to aid the interpretation of analogous outcrops and, more especially, subsurface depositional systems revealed only in cores.

Estuaria merupakan wilayah pesisir semi tertutup yang mempunyai hubungan bebas dengan laut terbuka dan menerima masukan air tawar dari daratan. Sebagian besar estuaria didominasi oleh substrat berlumpur yang merupakan endapan yang dibawa... more

Estuaria merupakan wilayah pesisir semi tertutup yang mempunyai hubungan bebas dengan laut terbuka dan menerima masukan air tawar dari daratan. Sebagian besar estuaria didominasi oleh substrat berlumpur yang merupakan endapan yang dibawa oleh air tawar dan air laut. Daerah perairan yang termasuk dalam estuaria ini adalah muara sungai, teluk dan rawa pasang surut. Estuaria daratan pesisir merupakan tipe estuaria yang paling umum dijumpai (Kamal, 2004)

The Barren Measures Formation (middle Permian, ~271e260 Ma), the non-coaliferous lithounit sandwitched between two major coal-bearing formations in the Indian Lower Gondwana succession, was earlier interpreted as continental... more

The Barren Measures Formation (middle Permian, ~271e260 Ma), the non-coaliferous lithounit sandwitched
between two major coal-bearing formations in the Indian Lower Gondwana succession, was
earlier interpreted as continental fluvio-lacustrine deposits. The present contribution documents sedimentary
attributes of marginal marine tideewave interference from the Barren Measures Formation of
eastern peninsular India, exposed along the Bokaro River section, West Bokaro Coalfield, Jharkhand.
Tidalites, including various tidal bundle sequences with frequent reactivation surfaces (velocity asymmetry)
and single/double mud drapes (pause planes), systematic arrangement of tidal beddings (flaser,
wavy, lenticular) and tidal rhythmites with alternate sand-dominated and mud-dominated planelaminated
units, manifest sedimentation by open marine springeneapespring tidal cycles under diurnal
inequalities in a semi-diurnal tidal system. The architecture of tidalites attests to sedimentation in
shallow subtidal to intertidal flat facies, affected by intermittent strong to week reworking by open
marine waves/storms. Wave reworking is manifested by wave ripples, combined-flow ripples and wavegenerated
tidal bundles. Their coexistence and gradation with tidalites indicate low-energy wave/storm
interference with tidal currents in a sheltered, tide-dominated estuary, especially on tidal flats along
estuary channel banks. Overall fining-up facies sequence, upward increase of prodeltaic mud over tide
ewave led sediments, signify a sustained transgressive phase onlaping the estuary system in eastern
peninsular India during middle Permian (Guadalupian).

The gobiid fish Mangarinus waterousi Herre, 1943 is recorded for the first time from India in Vellar estuary (n = 7) and Pazhayar fish landing (n = 3), Tamil Nadu. Their length ranged from 26.0 to 31.9 mm. Morphometric and meristic... more

The gobiid fish Mangarinus waterousi Herre, 1943 is recorded for the first time from India in Vellar estuary (n = 7) and Pazhayar fish landing (n = 3), Tamil Nadu. Their length ranged from 26.0 to 31.9 mm. Morphometric and meristic diagnostic characteristics have been measured and compared with type specimens of Mangarinus waterousi at California Academy of Sciences, San Francisco, USA. The record of this species from Tamil Nadu, India, significantly extends the known distribution of M. waterousi, previously reported from the Philippines, Brunei, Thailand, Indonesia, Japan, China (Hong Kong), Marshall Islands, Fiji and the Solomon Islands.

Plankton plays an important role in a body of water as the primary producers and the beginning of the chain in the food web (food chain) causes the plankton used as a measure of fertility an ecosystem scale. This study aims to analyze the... more

Plankton plays an important role in a body of water as the primary producers and the beginning of the chain in the food web (food chain) causes the plankton used as a measure of fertility an ecosystem scale. This study aims to analyze the diversity and community structure of plankton in order to describe the condition of waters in the estuary Perancak, Bali.. This research was conducted by field surveys in September 2015 (transitional season II), consisting of three location , namely data collection Loloan River (north), Dermaga Perancak (middle) and Muara Perancak (south). Based on the results, both plankton abundance of phytoplankton and zooplankton ranged between 300-20100 ind/m3 and 300-28500 ind/m3. An abundance of plankton in the Estuary Perancak influenced by the water quality, especially the concentration of nutrients (phosphate, silicate and nitrate). Ecological index showed that species diversity of phytoplankton in the Estuary Perancak was categorized as low diversity (0,98≤H'≤ 1.38) and no species of phytoplankton dominating (0,55≤E≤0,77) with uniformity kind of approaching a stable and tend evenly (0,32≤ D≤0,48). While the index showed that diverisity index of zooplankton is low (1,06≤H'≤1,29), with the distribution species are fairly uniform and relatively similar (0,54≤E≤1), and dominant species is not present (0,33≤D≤0,51). These results indicate that Perancak Estuary is moderate levels of water pollution. It is known from the low diversity index of phytoplankton and zooplankton in the waters of Perancak Estuary.
Keywords: plankton community structure, Perancak Estuary, abundance, diversity, dominance index.

Pada saat muson tenggara perairan selatan Jawa, Bali dan Nusa Tenggara mengalami upwelling yang berpengaruh ke perairan selat Bali disebut sebagai in-direct upwelling. Pengaruh upwelling ini bisa dilihat dari perubahan parameter fisika,... more

Pada saat muson tenggara perairan selatan Jawa, Bali dan Nusa Tenggara mengalami upwelling yang berpengaruh ke perairan selat Bali disebut sebagai in-direct upwelling. Pengaruh upwelling ini bisa dilihat dari perubahan parameter fisika, kimia dan biologi perairan seperti suhu, klorofil-a dan nutrien. Penelitian ini bertujuan untuk mengetahui pengaruh terjadinya upwelling terhadap distribusi suhu, klorofil-a dan nutrien terutama nitrat,
fosfat, dan silika di Selat Bali dari hasil observasi bulan Juni-September 2012. Lokasi penelitian di koordinat 8,4 LS – 8,85 LS dan 114,40 BT – 115,5 BT. Metode yang digunakan adalah observasi lapangan saat terjadinya upwelling. Pengukuran parameter suhu dan klorofil-a menggunakan Conductivity Temperature Depth (CTD). Sampel nutrien
diambil tiap layer kedalaman dari permukaan sampai 100 m dibagi menjadi 3 zona mewakili karaketristik perairan utara (Laut Bali), tengah (Selat Bali) dan selatan (Samudera Hindia). Hasil penelitian menunjukkan terjadi peningkatan konsentrasi nutrien yang terlihat dari peningkatan konsentrasi nitrat, fosfat, silikat dan klorofil-a serta penurunan suhu. Konsentrasi klorofil-a maksimum di kedalaman 20 m zona selatan yang berhubungan langsung dengan Samudera Hindia dan terjadi kenaikan massa air dingin dikedalaman 70 m serta peningkatan konsentrasi fosfat di kedalaman 60 m, hal ini memperkuat bahwa pada bulan Juni-September perairan selat Bali mendapatkan pengaruh upwelling kuat dari Samudera Hindia.
Kata kunci : in-direct upwelling, suhu, klorofil-a, nutrien

Australia's aquatic ecosystems are unique, supporting a high diversity of species and high levels of endemism; however, they are also extremely vulnerable to climate change. The present review assesses climate-induced changes to... more

Australia's aquatic ecosystems are unique, supporting a high diversity of species and high levels of endemism; however, they are also extremely vulnerable to climate change. The present review assesses climate-induced changes to structural habitats that have occurred in different aquatic ecosystems. Climatic impacts are often difficult to discern against the background of habitat degradation caused by more direct anthropogenic impacts. However, climate impacts will become more pronounced with ongoing changes in temperature, water chemistry, sea level, rainfall patterns and ocean currents. Each of these factors is likely to have specific effects on ecosystems, communities or species, and their relative importance varies across different marine and freshwater habitats. In the Murray-Darling Basin, the greatest concern relates to declines in surface water availability and riverine flow, owing to declining rainfall and increased evaporative loss. On the Great Barrier Reef, increasing temperatures and ocean acidification contribute to sustained and ongoing loss of habitat-forming corals. Despite the marked differences in major drivers and consequences of climate change, the solution is always the same. Greenhouse-gas emissions need to be reduced as a matter of urgency, while also minimising nonclimatic disturbances. Together, these actions will maximise opportunities for adaptation by species and increase ecosystem resilience.

The hyporheic zone is a potential refuge that can promote persistence of benthic 9

We review the distribution, status and ecology of Australian saltmarshes and the mechanisms whereby enhanced atmospheric carbon dioxide and associated climate change have influenced and will influence the provision of ecosystem goods and... more

We review the distribution, status and ecology of Australian saltmarshes and the mechanisms whereby enhanced atmospheric carbon dioxide and associated climate change have influenced and will influence the provision of ecosystem goods and services. Research in temperate and subtropical saltmarsh has demonstrated important trophic contributions to estuarine fisheries, mediated by the synchronised massspawning of crabs, which feed predominantly on the C-4 saltmarsh grass Sporobolus virginicus and microphytobenthos. Saltmarshes also provide unique feeding and habitat opportunities for several species of threatened microbats and birds, including migratory shorebirds. Saltmarshes increased in extent relative to mangrove in Australia in both tide-and wave-dominated geomorphic settings through the latter Holocene, although historic trends have seen a reversal of this trend. Australian saltmarshes have some capacity to maintain elevation with respect to rising sea level, although in south-eastern Australia, the encroachment of mangrove and, in Tasmania, conversion of shrubland to herbfield in the past half-century are consistent with changes in relative sea level. Modelling of the impacts of projected sea-level rise, incorporating sedimentation and other surface-elevation drivers, suggests that the survival of saltmarsh in developed estuaries will depend on the flexible management of hard structures and other impediments to wetland retreat.

Dryland rivers are renowned for their periods of 'boom' related to the episodic floods that extend over vast floodplains and fuel incredible production, and periods of 'bust' where the extensive channel network is restricted to the... more

Dryland rivers are renowned for their periods of 'boom' related to the episodic floods that extend over vast floodplains and fuel incredible production, and periods of 'bust' where the extensive channel network is restricted to the permanent refugial waterholes. Many of these 15 Dryland river waterholes -aquatic refugia 106, 110-127 570 Kennard, M. J. (1995).

The second largest zone of coastal hypoxia (oxygen-depleted waters) in the world is found on the northern Gulf of Mexico continental shelf adjacent to the outflows of the Mississippi and Atchafalaya Rivers. The combination of high... more

The second largest zone of coastal hypoxia (oxygen-depleted waters) in the world is found on the northern Gulf of Mexico continental shelf adjacent to the outflows of the Mississippi and Atchafalaya Rivers. The combination of high freshwater discharge, wind mixing, regional circulation, and summer warming controls the strength of stratification that goes through a well-defined seasonal cycle. The physical structure of the water column and high nutrient loads that enhance primary production lead to an annual formation of the hypoxic water mass that is dominant from spring through late summer. Paleoindicators in dated sediment cores indicate that hypoxic conditions likely began to appear around the turn of the last century and became more severe since the 1950s as the nitrate flux from the Mississippi River to the Gulf of Mexico tripled. Whereas increased nutrients enhance the production of some organisms, others are eliminated from water masses (they either emigrate from the area or die) where the oxygen level falls below 2 mg l −1 or lower for a prolonged period. A hypoxia-stressed benthos is typified by short-lived, smaller surface deposit-feeding polychaetes and the absence of marine invertebrates such as pericaridean crustaceans, bivalves, gastropods, and ophiuroids. The changes in benthic communities, along with the low dissolved oxygen, result in altered sediment structure and sediment biogeochemical cycles. Important fisheries are variably affected by increased or decreased food supplies, mortality, forced migration, reduction in suitable habitat, increased susceptibility to predation, and disruption of life cycles.

... phytoplankton and zooplankton have been established in estuarine systems ([Sautour et al., 1996], [Perissinotto et al., 2000] and [Tan et al ... Maximum number of microzooplankton species (seven) observed was at stations 1 and 6 only,... more

... phytoplankton and zooplankton have been established in estuarine systems ([Sautour et al., 1996], [Perissinotto et al., 2000] and [Tan et al ... Maximum number of microzooplankton species (seven) observed was at stations 1 and 6 only, but species like Tintinnidium incertum and ...

The remains of a timber v-shaped fishweir and associated structures have been discovered near Ashlett Creek on the tidal mudflats of Southampton Water in Hampshire, southern Britain. Radiocarbon dating of oak roundwood stakes taken from... more

The remains of a timber v-shaped fishweir and associated structures have been discovered near Ashlett Creek on the tidal mudflats of Southampton Water in Hampshire, southern Britain. Radiocarbon dating of oak roundwood stakes taken from the main weir structure date it to the middle Saxon period. Clusters of as-yet undated roundwood posts within the catchment area of the weir are interpreted as the frames for fish traps that are assumed to pre- or post-date the operational period of the weir itself. The weir is contemporary with wooden v-shaped fishweirs found elsewhere in southern and central Britain, and also Ireland, but its circular catchment ‘ pound’ remains unique, in these islands, to the Solent region: it has a close parallel with another Saxon-era weir on the nearby Isle of Wight. The weir also shows striking structural similarities with examples in use today in Basse Normandy, on the southern shore of the English Channel. The paper discusses the function and operation of the weir, and places it in its social and historical context. Finally, it considers the implications of the weir’ s dating for our understanding of saltmarsh morphodynamics in this south-western part of Southampton Water, and considers in turn the implications of these dynamics for the material survival of the site.

Many aquatic ecosystems have been severely degraded by water resource development impacting on flow regimes and biological connectivity. Freshwater fish have been particularly impacted by these changes and climate change will place... more

Many aquatic ecosystems have been severely degraded by water resource development impacting on flow regimes and biological connectivity. Freshwater fish have been particularly impacted by these changes and climate change will place further stress on them. The Murray-Darling Basin (MDB), Australia, represents a highly impacted aquatic system with dramatically modified flow regimes. This has impaired the health of its rivers, and potentially limited the adaptive capacity of its biota to respond to a changing climate. Here we present our predictions of the potential impacts of climate change on 18 native fish species across their distributional ranges against the back-drop of past and continuing water resource development (WRD). As most of these species are found across a wide range of geographical and hydrological settings we classified the MDB into ten regions to account for likely variation in climate change effects based on latitude, elevation and water resource development. Coldwater tolerant species will be under greater stress than warmwater tolerant species. In some regions the negative impacts on exotic fish such as trout will likely improve current conditions for native species. As the impacts of climate change on any given species are likely to vary from region to region, regional fish assemblages will also be differentially affected. The most impacted region is likely to occur in the highly disturbed Lower Murray River region, while the dryland rivers that are less impacted in the northern MDB are likely to remain largely 2 unchanged. While climate change is a current and future threat to the MDB fish fauna, the continued over-regulation of water resources will place as much, if not more stress on the remnant fish species.

Phytoplankton seasonal and interannual variability in the Guadiana upper estuary was analyzed during 1996-2005, a period that encompassed a climatic controlled reduction in river flow that was superimposed on the construction of a dam.... more

Phytoplankton seasonal and interannual variability in the Guadiana upper estuary was analyzed during 1996-2005, a period that encompassed a climatic controlled reduction in river flow that was superimposed on the construction of a dam. Phytoplankton seasonal patterns revealed an alternation between a persistent light limitation and episodic nutrient limitation. Phytoplankton succession, with early spring diatom blooms and summer-early fall cyanobacterial blooms, was apparently driven by changes in nutrients, water temperature, and turbulence, clearly demonstrating the role of river flow and climate variability. Light intensity in the mixed layer was a prevalent driver of phytoplankton interannual variability, and the increased turbidity caused by the Alqueva dam construction was linked to pronounced decreases in chlorophyll a concentration, particularly at the start and end of the phytoplankton growing period. Decreases in annual maximum and average abundances of diatoms, green algae, and cyanobacteria were also detected. Furthermore, chlorophyll a decreases after dam filling and a decrease in turbidity may point to a shift from light limitation towards a more nutrient-limited mode in the near future.

Although many species of zoosporic true fungi have been frequently observed and studied in freshwater and soil ecosystems, only three species have been properly identified and partially characterised from brackish and marine ecosystems,... more

Although many species of zoosporic true fungi have been frequently observed and studied in freshwater and soil ecosystems, only three species have been properly identified and partially characterised from brackish and marine ecosystems, namely Rhizophydium littoreum Amon, Thalassochytrium gracilariopsis Nyvall, Pedersén et Longcore and Chytridium polysiphoniae Cohn. These species are either facultative or obligate parasites of marine macroalgae and invertebrates. Also, some species of Olpidium and Rhizophydium are parasites of small marine green algae and diatoms. Although the physiological effects of these pathogens on the growth and metabolism of their hosts are poorly understood, parasitism by C. polysiphoniae possibly affects the rates of photosynthesis and patterns of growth in infected communities of brown algae. Saprobic ecotypes of R. littoreum can also colonise dead-plant and animal substrates. Zoospores from zoosporic true fungi and other groups of microbes possibly provide important food resources for grazing and filter-feeding zooplankton and metazoans in marine ecosystems where the prevalence of disease is high or where accumulated detritus enhances biodiversity in food webs. However, quantitative studies have not yet been attempted. Recently, environmental sampling with molecular techniques has revealed unknown clades of zoosporic true fungi in extreme marine ecosystems. These fungi have been grossly under-sampled and under-studied in marine environments.

... Perillo, GME, 1995. Definitions and geomorphologic classifications of estuaries. In: Perillo, GME (Ed.), Geomorphology and Sedimentology of Estuaries. Developments in Sedimentology, 53. ... De. Galaxia Vigo. pp. 237–250. Varela, M.,... more

... Perillo, GME, 1995. Definitions and geomorphologic classifications of estuaries. In: Perillo, GME (Ed.), Geomorphology and Sedimentology of Estuaries. Developments in Sedimentology, 53. ... De. Galaxia Vigo. pp. 237–250. Varela, M., Prego, R., Canle, M. and Lorenzo, J., 1994. ...

The freshwater fish, Rhadinocentrus ornatus Regan, 1914, has a patchy distribution through coastal drainages of Queensland and New South Wales, eastern Australia. Isolated populations of R. ornatus are found on several islands, as well as... more

The freshwater fish, Rhadinocentrus ornatus Regan, 1914, has a patchy distribution through coastal drainages of Queensland and New South Wales, eastern Australia. Isolated populations of R. ornatus are found on several islands, as well as in a disjunct northern population 350 km from its nearest conspecific population. Deoxyribonucleic acid was extracted and sequenced for the mitochondrial ATPase gene to describe the geographic and genetic subdivision within the species. Four major clades were identified. These clades diverged between two and seven million years ago and so represent long-term divisions and possible units of conservation. There are conservation implications in that the narrow and localised distribution of R. ornatus overlaps with an area of large-scale land clearing, high human population and threats from introduced exotic fish. A particularly high centre of Rhadinocentrus diversity in the Tin Can Bay area of Queensland presents some interesting questions about the e...

Systematic study of charts, maps and satellite images pertaining to 1967-68, 1975, 1992, 1997, 2000, 2003, 2006, 2009 and 2012, indicate that the Balari Bar steadily increased, choking up the northern portion of the Haldia Channel, on the... more

Systematic study of charts, maps and satellite images pertaining to 1967-68, 1975, 1992, 1997, 2000, 2003, 2006, 2009 and 2012, indicate that the Balari Bar steadily increased, choking up the northern portion of the Haldia Channel, on the west of the Hugli Estuary. Its rapid growth, from 0.29 km^2 in 1997 to 3.83 km^2 in 2012, started to threaten the Haldia Dock Complex (HDC). Eight superimposed profiles across the 15 km Balari Reach of the estuary show gradual deterioration of the western Haldia Channel and the improvement of the eastern Rangafalla Channel resulting in the concentration of the tidal flows in the latter. The decrease in the overall capacity of the reach has been 8.13% from 2000 to 2012. The result of this is reflected on the performance of the HDC as some of its share of cargo is diverted to the other sea ports in the vicinity.

In this study we investigate for the first time the zooplankton assemblages in a relatively small tidal channel called Bahía del Medio, situated in the middle-outer area of the Bahía Blanca Estuary, South of the Main channel. We focused... more

In this study we investigate for the first time the zooplankton assemblages in a relatively small tidal channel called Bahía del Medio, situated in the middle-outer area of the Bahía Blanca Estuary, South of the Main channel. We focused the study on micro- and mesozooplankton assemblages with emphasis on tintinnids, copepods and meroplankton along the annual cycle 1997-1998. Fifteen species of tintinnids belonging to 6 genera were observed in the study area, the mean total tintinnid abundance fluctuating between 3.4 x 106 ind. m-3 and 5.1 x 106 ind m-3. The mesozooplankton comprised 11 taxa, total abundance fluctuating between 449 ind m-3 in March 1997 and only 1 ind m-3 in October 1997. The channel proved to be spatially homogeneous in its physical and biochemical features. Micro- and mesozooplankton abundance displayed a high degree of spatial homogeneity, though the seasonal variation in both environment and zooplankton was significant. Comparison with the zooplankton observed at a station in the Main channel of the estuary showed differences in number of taxa represented, a general lower abundance of both assemblages and the presence of some rare species, a fact which is discussed.

Surface sediments collected at the Tirumalairajan river estuary and their surrounding coastal areas were analyzed for the bulk metal concentration. The sedi- ments were collected from post- and premonsoon sea- sons. Dominances of heavy... more

Surface sediments collected at the Tirumalairajan river estuary and their surrounding coastal areas were analyzed for the bulk metal concentration. The sedi- ments were collected from post- and premonsoon sea- sons. Dominances of heavy metals are in the following order: Fe>Mn>Zn >Pb>Cu in bothseasons from estuary and coastal area. The results reveal that Fe, Mn, Cu,Pb, andZndemonstratedanincreased patternfrom the estuary when compared to the coastal area. The heavy metal pattern of the sediments of the Tirumalair- ajan river estuary and its surrounding coastal area of- fered strong evidence that the coastal area was a major source of heavy metals to the estuarine region. For various metals, the contamination factor and geoaccu- mulation index (Igeo) have been calculated to assess the degree of pollution in sediments. The contamination factor and geoaccumulation index show that Zn, Pb, and Cu unpolluted to moderately pollute the sediments in estuarine part. This study shows the major sources of metal contamination in catchment and anthropogenic ones, such as agriculture runoff, discharge of industrial wastewater, and municipal sewage through the estuary and adjoining coastal area.

Most of the estuarine and ocean bottoms are covered with sediments making this the largest habitat on our planet. Grain size data of the estuarine sediments are of great importance in differentiating various depositional microenvironments... more

Most of the estuarine and ocean bottoms are covered with sediments making this the largest habitat on our planet. Grain size data of the estuarine sediments are of great importance in differentiating various depositional microenvironments and also useful for assessing the textural characteristics of the habitat in benthic ecological studies. Here we use grain size analysis of the intertidal surface sediments along the Brunei estuary (Borneo, South East Asia) and the result reveals the dominance of sand fractions, and the percentage of dominance follows the order of sand > clay > silt. The sand size fraction was higher at seaward stations, which were poor in organic matter (<4 %), in contrast to the low-energy landward stations, which comprised a higher proportion of fine-grained (clay and silt) sediments and were rich in organic matter (> 5%). This pattern suggests that the intertidal sediments of the estuary derive from a mixed origin, including continental/marine and terrestrial sources, which vary in degree along the estuarine gradient in relation to hydrodynamic wave/current energy (generally low to high in a seaward direction along the estuary). There was strong negative correlation between the sand fraction and the other sediment variables (silt, clay and organic matter), whereas a positive correlation was observed between organic matter and silt/clay. Univariate (ANOVA) and multivariate (PCA) techniques clearly showed significant spatial differences in the sediment variables among the stations investigated, confirming differential energy conditions at different locations. Cluster analysis and PCA helped to discriminate the station groups along the estuary according to their sediment textural properties. This study also revealed that sediment grain size is a key factor influencing the organic matter accumulation in surface sediments. The organic matter observed in different stations is quite in agreement with the widely accepted view of other researchers from the tropical region that fine grained sediments generally have higher amounts of organic matter than the coarse grained one. The high organic matter at landward stations was found to reflect natural (mangroves) and anthropogenic (pollution) organic input.