Plankton, Copepods Research Papers - Academia.edu (original) (raw)

Background Iceland has high availability of freshwater, and it is rich in brackish and coastal aquatic bodies. However, knowledge on rotifers and meiobenthic and planktonic crustaceans inhabiting these habitats is lacking, and the inland... more

Amylase activity in a calanoid copepod, Heliodiaptomus cinctus, exhibited a rhythmic pattern of diel variation with a peak in the early morning and a minimum level in the evening. In a normal food state and in a metal ion stress state,... more

Amylase activity in a calanoid copepod, Heliodiaptomus cinctus, exhibited a rhythmic pattern of diel variation with a peak in the early morning and a minimum level in the evening. In a normal food state and in a metal ion stress state, the enzyme activity decreases through time but in a food scarce state amylase activity exhibited a short-term increase followed by a decline.

and the Palk Bay (PB) — two least studied marine environments located between India and Sri Lanka. The study is based on the results obtained from a field sampling exercise carried out in the GoM and the PB in March 2010 (Spring... more

and the Palk Bay (PB) — two least studied marine environments located between India and Sri Lanka. The
study is based on the results obtained from a field sampling exercise carried out in the GoM and the PB in
March 2010 (Spring Intermonsoon — SIM), September 2010 (Southwest Monsoon — SWM) and January
2011 (Northeast Monsoon — NEM). Based on multivariate analysis of major environmental parameters during
different seasons, it was possible to clearly segregate the GoM and the PB into separate clusters, except
during the SWM. This segregation of the GoM and the PB was closely linked with the seasonally reversing
ocean currents in the region, as evident from the MIKE 21 flow model results. During the period of relatively
low phytoplankton biomass (b23 mg C m−3), the organic carbon contribution of the microbial loop was significantly
high — both in the GoM and the PB. During the SIM, the carbon biomass available in the plankton
food web was significantly higher in the PB (av. 122.8±47.60 mg C m−3) than in the GoM (av. 81.89±
35.50 mg C m−3). This was due to a strong microbial loop in the former region. In the GoM, phytoplankton
contributed a considerable portion (>50%) of the carbon biomass during the SWM and the NEM, whereas,
microbial loop contributed significantly (80%) during the SIM. The microbial loop was predominant in the
PB throughout the study period, being as high as 83% of the total plankton biomass during the SIM. As
compared to the PB, the mesozooplankton biomass was higher in the GoM during the SWM and the NEM
and lower during the SIM. The relatively high mesozooplankton stock in the PB during the SIM was closely
linked with a strong microbial loop, which contributed the major share (av. 101.6±24.3 mg C m−3) of the
total organic carbon available in the food web (av. 126.6±24.3 mg C m−3). However, when microbial loop
contributed >65% of the total organic carbon available in the food web, the trophic efficiency was found to
be low (~3%), which can be attributed to the wide dispersal of organic carbon in the microbial loop. Importantly,
during the NEM, when the copepod Paracalanus parvus was predominant in the PB, the trophic efficiency
of the microbial loop dominant food web increased by more than a fold (7.2%). The study provides
evidences for the first time from the field that exceptionally high abundance of efficient microzooplanktonconsuming
zooplankton can significantly increase the trophic efficiency of the microbial loop dominant
plankton food web.

Recent surveys have recorded cosmopolitan cyclopoid copepods such as Macrocyclops albidus, Meso-cyclops aspericorni, Microcyclops varicans and Eucyclops agilis from Cueva Clara de Empalme (or Cueva Clara) in the Río Camuy Caves Park of... more

Recent surveys have recorded cosmopolitan cyclopoid copepods such as Macrocyclops albidus, Meso-cyclops aspericorni, Microcyclops varicans and Eucyclops agilis from Cueva Clara de Empalme (or Cueva Clara) in the Río Camuy Caves Park of the Río Camuy Cave System (RCCS) in the northern karst of Puerto Rico. Our findings do not support the widely accepted notion that cave dwelling organisms are for the most part endemic and/or highly specialized species, leading to the conclusion that not all cave fauna is necessarily endemic. Further detailed examination of cave-dwelling copepod fauna using molecular techniques would prove beneficial in determining whether species found are indeed individuals of a particular species with a wide distribution, or if the presence of cryptic species is a viable explanation.

Long-term studies are necessary to gain insight into the influence of external climate forcing on zooplankton dynamics. Using monthly time series (1993–2010) collected in the Cantabrian Sea (southern Bay of Biscay), we studied long-term... more

Long-term studies are necessary to gain insight into the influence of external climate forcing on zooplankton dynamics. Using monthly time series (1993–2010) collected in the Cantabrian Sea (southern Bay of Biscay), we studied long-term trends and seasonal cycles of zooplankton abundance and biomass along a coastal-ocean gradient. We also analysed changes in environmental variables such as sea surface temperature (SST) and chlorophyll a concentration. Zooplankton abundance and biomass increased during the study period, with greater increases in biomass towards the coast and for larger size classes. These results contrast with the decrease in biomass and size expected under global warming, which is shown in the region by the rise in summer SST, suggesting the operation of other processes. Indeed, winter mixing and coastal upwelling were key drivers of zooplankton dynamics in spring and autumn, respectively. In these seasons, zooplankton inter-annual increases were stronger. Including these hydrographic processes in future models of zooplankton dynamics for the Bay of Biscay and other temperate areas will improve their accuracy. Our results highlight the importance of disentangling the main mechanisms behind long-term changes in zooplankton, especially within the context of climate change.

We examined the impacts of ocean acidification and copper as co-stressors on the reproduction and population level responses of the benthic copepod Tisbe battagliai across two generations. Naupliar production, growth, and cuticle... more

We examined the impacts of ocean acidification and copper as co-stressors on the reproduction and population level
responses of the benthic copepod Tisbe battagliai across two generations. Naupliar production, growth, and cuticle
elemental composition were determined for four pH values: 8.06 (control); 7.95; 7.82; 7.67, with copper addition to
concentrations equivalent to those in benthic pore waters. An additive synergistic effect was observed; the decline in
naupliar production was greater with added copper at decreasing pH than for decreasing pH alone. Naupliar production
modelled for the two generations revealed a negative synergistic impact between ocean acidification and environmentally
relevant copper concentrations. Conversely, copper addition enhanced copepod growth, with larger copepods produced at
each pH compared to the impact of pH alone. Copepod digests revealed significantly reduced cuticle concentrations of
sulphur, phosphorus and calcium under decreasing pH; further, copper uptake increased to toxic levels that lead to reduced
naupliar production. These data suggest that ocean acidification will enhance copper bioavailability, resulting in larger, but
less fecund individuals that may have an overall detrimental outcome for copepod populations.

Invasion of alien species to a stabilized ecosystem as a rule impair significantly the structure and functioning of aboriginal communities. Alternative scenario was demonstrated by the small marine cyclopoid copepod Oithona davisae... more

Invasion of alien species to a stabilized ecosystem as a rule impair significantly the structure and functioning of aboriginal communities. Alternative scenario was demonstrated by the
small marine cyclopoid copepod Oithona davisae Ferrari and Orsi 1984, introduced into Sevastopol Bay (North-Western Crimean shelf of the Black Sea) obviously with ballast
waters in early 2000s, becoming a permanent resident since 2005 and a dominant species in summer-autumn copepod community in 2008-2014, attaining up to 90% of total number of overall copepods species composition and reaching periodically a population density of more than 1000 L-1. Survival and wide dissemination of this non-indigenous Asian species in lower salinity and winter temperatures of the Black Sea environment was possible due to its unique adaptive strategy. Invader did not affect adversely the structure of neither zooplankton, nor phytoplankton communities due to its high adjustment metabolism and flexible feeding behaviour, high survival rate in adverse food conditions and high reproduction rates in favorable conditions. Spatio-temporal matching of high number of O. davisae with reproduction of summer spawning fishes resulted in its significant contribution (30 - 90% of gut contents) into the diet of the larvae and fingerlings of numerous species and increased their growth and survival.

Copepod comprised 49.5% of the total crustacean zooplankton in a macrophyte-infested wetland. Cyclopoids and Calanoids represented 82% and 18% the total copepod respectively. Of the seven species of copepods encountered Mesocyclops... more

Copepod comprised 49.5% of the total crustacean zooplankton in a macrophyte-infested wetland. Cyclopoids and Calanoids represented 82% and 18% the total copepod respectively. Of the seven species of copepods encountered Mesocyclops thermocyclopoides Harada, 1931 was a eudominant species and Microcyclops varicans Gurney, 1933 Eucyclops serrulatus Fischer, 1851, Thermocyclops oithonoides Keifer, 1978 and H. cinctus (Gurney, 1907) were dominant species. Copepod species mostly had a positive association among themselves indicating overlapping ecological niche to some extent. A few, however, exhibited a negative association indicating some sort of competition and niche separation. Cyclopoid density varied from month to month and showed winter, summer and spring peaks, while Calanoids showed bimodal fluctuation pattern with peaks in spring and autumn. Fluctuation pattern varied from one species to other. M. thermocyclopoides achieved peak population in summer and T. oithonoides in winter. Both the species thus avoid competition by adopting alternate peaks. Coexistence of seven species of copepods was possible by adopting distinct life cycle strategies, following different fluctuation pattern.

Individual specimens of Euterpina acutifrons (Copepoda: Harpacticoida) taken from the mass cultures of the C.N.E.N.-EURATOM Laboratory at Fiascherino, Italy, were reared in new culture media prepared with suspensions of several species of... more

Individual specimens of Euterpina acutifrons (Copepoda: Harpacticoida) taken from the mass cultures of the C.N.E.N.-EURATOM Laboratory at Fiascherino, Italy, were reared in new culture media prepared with suspensions of several species of algae in filtered and sterilized sea water. All the experiments were carried out at a temperature of 18°C±1 C°. The influence of food concentrations on adult life-span and reproductive activity of E. acutifrons was analyzed. A good correlation was found between concentration of algal suspension and egg production. Maximum life-span was observed at intermediate values of food concentration. Other experiments were carried out to determine egg fertility and duration of the various embryonic and postembryonic development stages. Embryonic development time was calculated as approximately 2 days; the adult females appeared 10 to 12 days after hatching of Nauplius I. Production of nauplii by 6 females reared under conditions of excess food supply was also studied. These conditions were achieved by supplying high concentrations of a mixture of 4 different algal species and by completely renewing the culture medium at frequent intervals. Under these conditions, each female laid an average of 12.5 sacs and produced an average of 294.3 nauplii. An average production of 355.5 eggs per female was estimated. An analysis was made of growth in size and weight of the females: the average daily egg production in terms of dry weight corresponded to about 32% of the biomass of the adult female. Birch's (1948) method was used to calculate net reproduction rate (R o=70.89), intrinsic rate of increase (r m=0.161) and mean generation time (T=26.5 days).