Changes In Zooplankton Composition Research Articles

Drivers of spatial and temporal micro- and mesozooplankton dynamics in an estuary under strong anthropogenic influences (The Eastern Scheldt, Netherlands)

The Eastern Scheldt estuary in the Netherlands has been anthropogenically changed by the construction of a storm surge barrier about 30 years ago, affecting abiotic conditions as well as phytoplankton and zooplankton (ZP). As the ZP communities have not been sampled in the last decades, it is unclear to what extent they have changed during the last 30 years. We analyzed the micro- and mesoZP composition and background parameters at eight stations in the Eastern Scheldt in spring, summer, and autumn 2018. Additionally, we conducted dilution experiments to estimate phytoplankton growth and microZP grazing rates. Seasonal variability of ZP was higher than spatial variability, but there were differences between stations. In agreement with data from the 1980s, we identified salinity and chlorophyll a as the most important factors in explaining the ZP community. Suspended particulate matter and water retention time were additionally identified for mesoZP, as well as dissolved inorganic nitrogen and phosphate concentration for microZP. We observed some changes in ZP composition with respect to the 1980s, most of which could be explained by the changes induced by the barrier construction. However, increased abundances of the cyclopoid copepod Oithona sp. were likely related to changes in phytoplankton composition due to large-scale bivalve cultivation in the estuary. Phytoplankton growth and microZP grazing rates were variable between seasons, which could be explained by changes in the phytoplankton community during the annual plankton succession. Overall, the observed alterations in the ZP community due to changed background parameters and intense bivalve filtration could affect the microbial loop as well as consumers of mesoZP and thus the functioning of the pelagic food web.

Research on the seasonal variation of zooplankton community in Daya Bay, South China Sea

Changes in zooplankton composition, abundance, and some species in response to environmental variation were investigated over four seasons (2020) in Daya Bay. In total, 129 taxa of zooplankton (16 groups of planktonic larvae and 20 indeterminate species) were identified. Zooplankton communities exhibited a significant seasonal shift in abundance and taxonomic composition. The maximum number of zooplankton species was recorded in winter (72 species) and the lowest in spring (42 species). However, the abundance was highest in spring (1,372.01 ± 1,071.14 individuals/m³) and lowest in autumn (50.93 ± 34.05 individuals/m³). Pearson correlation analyses demonstrated that the zooplankton abundance and the variations of indicator species were obviously correlated with environmental parameters (e.g., salinity, temperature, pH, and chlorophyll-a). Based on specificity and occupancy analysis, a total of eight species were selected as indicator species. It is noteworthy that some kollaplankton (such as Dolioletta gegenbauri and Doliolum denticulatum) could potentially cause disaster to the nuclear power plant cooling system because of their relatively large body size and huge blooms in spring. In addition, Centropages tenuiremis blooms in spring and Penilia avirostris blooms in summer could attract assemblages of larval or adult pelagic fish, which would also threaten the cooling system security in Daya Bay. In conclusion, our results suggest that zooplankton communities and some species may be considered as favorable indicators of the marine environment.

Zooplankton community structure of a tropical lake in a Northcentral State, Nigeria

One of the biological components that play a vital role in the ecological integrity of an aquatic ecosystem is zooplankton. These organisms are good indicators of stressors, especially anthropogenic stressors in their environment. Thus, there is a need to study the diversity in a diversified freshwater lake (Dangana Lake) in order to provide baseline information and knowledge on the status of the lake for proper and adequate water preservation and conservation. In addition to the zooplankton structure determination, the study also examined the physicochemical parameters of the Lake. Three sampling sites were identified with distinct characteristics where water and zooplankton samples were collected for physicochemical analyses and biotic identification using standard protocols. Sampling was conducted for a duration of eight months. The monitored physicochemical parameters, i.e., temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD5) and pH revealed no significant difference (p>0.05) among sampling sites. However, significance (p<0.05) amongst sampling sites was recorded in electrical conductivity, nitrate and phosphate. Seasonally, there was a significant difference (p<0.05) among sampling months in all the monitored parameters. A total of ten species of zooplankton were recorded with four species each of rotifera and copepoda and two species of cladocera. The order of abundance of zooplankton population was rotifera (56.39%), copepoda (29.18%) and cladocera (14.42%). Zooplankton population was significantly (p<0.05) higher during the dry season than in the rainy season. The Canonical correspondence analysis (CCA) revealed a strong correlation between the zooplankton and physicochemical parameters. Ipso-facto, the lake exhibited spatiotemporal changes in zooplankton composition and physicochemical parameters during the sampling period.

Zooplankton community associated with mesophotic coral reefs in the Colombian Caribbean Sea

The morphological, phenological and ecological characteristics of shallow coral reefs have been widely studied, but only recently have mesophotic corals begun to be studied. Very little is known about these ecosystems and their associated communities, such as the zooplankton community, which constitutes a food source for reefs and for the organisms that inhabit them. In the present study, changes in zooplankton composition were characterised during two hydroclimatic periods in a mesophotic environment of the submarine mountain Bajo Frijol, in Corales de Profundidad National Natural Park, Colombia. Zooplankton was collected using a portable pumping device, which contained three collectors of differing mesh sizes; this allowed the capture of zooplankton ranging in size from 45 to 300 μm. Temperature, conductivity, oxygen and pH were obtained and complemented with MODIS AQUA satellite information. In this ecosystem, the zooplankton organisms with the greatest richness and abundance were small-sized copepods, radiolarians and tintinnids. The oceanography of the area results in greater zooplankton abundance, richness, and diversity in June when the coastal current allows greater chlorophyll-a concentrations in the area and smaller organisms are favoured by greater retention within the corals of the mesophotic system. The biodiversity reported for Bajo Frijol is the first detailed approach to the community of mesophotic coral reefs in the Colombian Caribbean Sea, contributing to new records to the Global Biodiversity Information Facility.

Zooplankton communities in Lake Nasser, Egypt, under the current flood regime, before the construction of Grand Ethiopian Renaissance Dam (GERD)

This study focuses on changes in zooplankton composition and abundance in Lake Nasser during different flood periods before the construction of the Grand Ethiopian Renaissance Dam (GERD). Field surveys were carried out in August 2016 (flood period), December 2016 (post-flood period), and May 2017 (pre-flood period). Fifteen sampling sites representing five sectors were selected to cover the lake whole area. The results revealed a highly significant difference (p ≤ 0.016) in the density of all identified zooplankton groups among different flood seasons and lake locations. The zooplankton standing crop during the flood was higher, by a factor of approximately 3.7, than that recorded in post-flood and pre-flood periods. Zooplankton was dominated by medium-sized Copepoda, two cyclopoids (Thermocyclops neglectus and Mesocyclops ogunnus) and one calanoid (Thermodiaptomus galebi). The euplanktonic rotifer Keratella cochlearis dominated, during post-flood and pre-flood periods, constituting approximately 83% and 77% of total rotifer densities, respectively. Keratella tropica occurred in greatest density during flood made up 52.6% of total rotifers. Diaphanosoma mongolianum was the main cladoceran during flood and post-flood periods, whereas Ceriodaphnia dubia densities were highest for pre-flood periods. This study found that flood regime affect zooplankton composition and density in Lake Nasser.

Climate Change Vulnerability of American Lobster Fishing Communities in Atlantic Canada

Climate change impacts on fisheries will undoubtedly have socio-economic impacts on coastal communities and the seafood market. However, it is a challenge to integrate climate change information in a form that can be used efficiently by adaptation planners, policy makers and fishery managers. In this study, we frame a climate change impact assessment using a geographical perspective based on the management units of the dominant fishery, in this case, American lobster in Nova Scotia, Canada. The information considered here includes economic dependence on the fishery, population size, diversity of the fishery revenue, status of harbour infrastructure, total replacement cost of each harbour, increased relative sea level and flooding, and the vulnerability of offshore lobster to ocean warming and changes in zooplankton composition and anticipatory changes in fishery productivity across management borders. Using two ocean models to provide multi-decadal scale projections of bottom temperature, changes in offshore lobster distribution are projected to have a neutral, or positive impact on the region as a whole. However, when lobster vulnerability is combined with climate change related vulnerabilities of coastal fishing communities, it is evident that adaptation planning is needed for long-term sustainability. This impact assessment provides both a framework and information for further in-depth analyses by climate change adaptation planners and fishery managers.

Faunistic survey of the zooplankton community in an oligotrophic sinkhole, Cenote Azul (Quintana Roo, Mexico), using different sampling methods, and documented with DNA barcodes

This study is the first faunistic inventory of a zooplankton community from an open, karstic and oligotrophic aquatic sinkhole in the south of the Yucatan Peninsula (Mexico), we describe the richness of the zooplankton collected with the combination of plankton nets and light traps of our own design, using morphological and molecular characters to identify the species and demonstrate the effectiveness of only one set of primers to sequence all taxa. Recently, it has been demonstrated that different sampling methods can increase the number of zooplankton species from tropical and temperate systems dramatically. These more effective methods together with DNA barcoding can give a new and more realistic picture of the species dwelling in a freshwater system. In total, we sequenced 268 specimens, and the list of species known in this sinkhole increased from 13 to 77 taxa, with a projection of 87 in total, including cladocerans, copepods, ostracods, fish larvae, tadpoles, rotifers, chironomids, water mites, among others. From the 77 taxa identified by us, 72 BINS (Barcode Index Numbers, equivalent to putative species) were assigned by the BOLD Database (boldsystems.org), and 30 of them are new records for both, BOLD and GenBank (www.ncbi.nlm.nih.gov). There was an essential difference in the number of taxa collected with the plankton nets and the light traps. Only 23 taxa were registered in the nets, representing between 28 and 29% of the total richness, while 67 were present in the light traps representing 87% of the species found. From these, 46 taxa were exclusive to this sampling method. Light traps are an effective method for rapid evaluation of zooplankton. In the future, combining DNA barcoding and high-throughput sequencing methods with more  efficient collecting will enable us to perform quick and precise biomonitoring of any aquatic ecosystem, enabling the detection of changes in zooplankton composition resulting from climate change and anthropogenic disturbances. Nevertheless, as a first step it is fundamental to establish a baseline of DNA barcodes for the species in these ecosystems.

Zooplankton-phytoplankton interactions in Green Bay, Lake Michigan: Lower food web responses to biological invasions

Abstract As the largest freshwater estuary in the Laurentian Great Lakes, Green Bay, Lake Michigan (USA) is an important ecosystem presenting both challenges and opportunities for investigating changes in the face of multiple anthropogenic stressors. We collected new data from 2000 to 2007 to assess changes in lower food web interactions after establishment of invasive species (Bythotrephes longimanus and Morone americana in 1988 and Dreissena polymorpha in 1993) and nutrient reductions (1990s). Phytoplankton and zooplankton biomass and composition, as well as primary productivity and zooplankton community grazing rates, were determined along the previously well-studied trophic gradient from the shallow Lower bay to the stratified, open-water Middle bay. A clear trophic gradient still occurred during 2000–2007, with higher nutrients, phytoplankton and zooplankton in Lower bay compared to Middle bay. Phytoplankton abundance and cyanobacteria dominance increased significantly compared to earlier studies. However, integrated primary productivity did not change significantly at either Lower or Middle bay. Zooplankton standing stock decreased in Lower bay, driven primarily by reductions of bosminids, chydorids, and cyclopoid copepods, but did not change in Middle bay. Zooplankton community grazing rates did not change significantly, but shifts in magnitude and seasonality of net phytoplankton growth rates are consistent with increased phytoplankton standing stocks. Changes in zooplankton composition indicate increased predation by invertebrates and decreased fish predation. Shifts in both bottom-up and top-down factors have occurred, with Lower and Middle bay regions more eutrophic and similar to each other as a result of changes in this highly productive Great Lakes embayment.

Mesozooplankton grazing impact on phytoplankton in the northern regions of the Kara Sea in autumn

The role of mass zooplankton species, copepods Pseudocalanus spp. and Oithona spp. and pteropods Limacina helicina, in grazing impact on phytoplankon in the upper 50 m layer was investigated. Material was collected at 14 stations along two sections crossing the outer shelf, continental slope and adjacent deep-water regions in the western and eastern branches of St. Anna trough (Kara Sea) in September 2011. Feeding rate was measured with fluorescence method. It was shown that total grazing impact on phytoplankton varied in a wide range from 0.2 to 8.7% of biomass and from 2 to 230% of daily primary production. The main contribution to phytoplankton grazing was made by small copepods Oithona spp. and juvenile pteropods. Maximum values of grazing were found in the frontal zones over the slope, minimum–over the outer continental shelf. Significant mesoscale spatial heterogeneity in total zooplankton grazing due to the changes in zooplankton composition and abundance was observed.

Diversity and Seasonal Fluctuation of Zooplankton in Ghagardara Pond, Taluka Kandhar Dist. Nanded

In the present investigation, an attempt has been made to enlist the zooplankton diversity in Ghagardara pond, Taluka Kandhar Dist. Nanded. Seasonal changes in composition of zooplankton were analyzed from September 2005 to August 2006. The major groups of zooplankton found during the study period were Rotifera, Cladocera, Copepoda and Ostracoda. The Copepods were abundant in Ghagardara pond. The water quality parameters have an influence on the diversity and distribution of zooplankton population in Ghagardara pond.

Temperature effects on phytoplankton diversity — The zooplankton link

Recent climate warming is expected to affect phytoplankton biomass and diversity in marine ecosystems. Temperature can act directly on phytoplankton (e.g. rendering physiological processes) or indirectly due to changes in zooplankton grazing activity. We tested experimentally the impact of increased temperature on natural phytoplankton and zooplankton communities using indoor mesocosms and combined the results from different experimental years applying a meta-analytic approach. We divided our analysis into three bloom phases to define the strength of temperature and zooplankton impacts on phytoplankton in different stages of bloom development. Within the constraints of an experiment, our results suggest that increased temperature and zooplankton grazing have similar effects on phytoplankton diversity, which are most apparent in the post-bloom phase, when zooplankton abundances reach the highest values. Moreover, we observed changes in zooplankton composition in response to warming and initial conditions, which can additionally affect phytoplankton diversity, because changing feeding preferences of zooplankton can affect phytoplankton community structure. We conclude that phytoplankton diversity is indirectly affected by temperature in the post-bloom phase through changing zooplankton composition and grazing activities. Before and during the bloom, however, these effects seem to be overruled by temperature enhanced bottom-up processes such as phytoplankton nutrient uptake.

Effects of liming and development of Curimbatá (Prochilodus lineatus) larvae on the abundance of zooplankton in fish ponds

AIM: We aimed to evaluate the influence of the correction of the water alkalinity in the fish ponds on the density of zooplankton under a period they were stocked with larvae of Prochilodus lineatus, a neotropical fish called "Curimbatá". METHODS: We used a factorial design completely randomized. In one plot (2 ponds) there was no correction of the alkalinity of the water (20 mg CaCO3.L-1) and in two others, this variable was adjusted weekly to values around 30 and 60 mg CaCO3.L-1 ¹, with two replicates each. Zooplankton was sampled weekly and the experiment lasted 63 days. RESULTS: Significant differences in the density of the zooplankton over time (F = 6.78, p < 0.05) were found and there was a sharp decrease in zooplankton density from first to second week, and successive small increases in density from the fourth week until the end of the experiment. When considering the entire study period, alkalinity correction 60 mg CaCO3.L-1 resulted in higher density of zooplankton. Great changes in zooplankton composition occurred. Rotifera were dominant at the beginning of the experiment and Cladocera and Copepoda in the later weeks possibly due to an interplay of dilution by rain and fish predation in the initial part of the experiment and due to both alkalinity correction and predation by both fish and predatory copepods from the fourth week until the end. CONCLUSION: The experiment corroborated the hypothesis that correction of water alkalinity in ponds does favor zooplankton development but also highlighted biotic and abiotic interaction of factors operating simultaneously.

Composition, diversity and short-term temporal fluctuations of zooplankton communities in fish culture ponds (Pindamonhangaba), SP

The present study aimed at evaluating the composition, diversity and short-term temporal fluctuations of zooplankton communities in fish ponds. The study was carried out in two fish ponds, with 180 m(2) of water surface (6 x 30 m) each, located in the Aquiculture Centre of the Pindamonhangaba Fisheries Institute - São Paulo. The study was developed over eight weeks, from February 16 to April 6, 1998. The physical and chemical conditions of the water in the fish ponds were adequate for zooplankton development. The zooplanktonic community was characterised by high richness of species and a greater diversity was observed in the first fish pond, with a superior density of Rotifera. Temporal changes in zooplankton composition occurred in both ponds with Cladocera appearing in abundance later, in the fourth week, whereas copepods and rotifers were well represented since the beginning. Many species found are typical of fish ponds and are considered to constitute an excellent food source, showing high nutritional value for fish larvae, a good example being individuals from the Rotifera group and the micro-crustacean species Moina minuta and Thermocyclops decipiens.

Effect of eutrophication on changes in the composition of zooplankton in the Grošnica Reservoir (Serbia, Yugoslavia)

The present paper cites results of 2-year research on zooplankton in the Grosnica Reservoir near Kragujevac during the period 1996–98. Comparison of the obtained results with those of earlier investigations performed during the period 1950–52 showed that changes have occurred in the interval. A significant increase was recorded in the number of zooplankton species, and only a small number of previously registered species were not recorded again. Considerable changes in the faunistic composition of zooplankton are also indicated by the low value of the Sorenson similarity index (32.12%) and Jaccard index (19.13%). At the same time, the abundance of zooplankton increased markedly, which suggests to us intensification of eutrophicaton processes. On the basis of the composition and abundance of zooplankton, it can be assumed that the Grosnica Reservoir belongs to the category of meso-oligotrophic lakes.

Zooplankton-mediated changes of bacterial community structure

Enclosure experiments in the mesotrophic Schöhsee in northern Germany were designed to study the impact of metazooplankton on components of the microbial food web (bacteria, flagellates, ciliates). Zooplankton was manipulated in 500-liter epilimnetic mesocosms so that either Daphnia or copepods were dominating, or metazooplankton was virtually absent. The bacterial community responded immediately to changes in zooplankton composition. Biomass, productivity, and especially the morphology of the bacteria changed drastically in the different treatments. Cascading predation effects on the bacterioplankton were transmitted mainly by phagotrophic protozoans which had changed in species composition and biomass. When Daphnia dominated, protozoans were largely suppressed and the original morphological structure of the bacteria (mainly small rods and cocci) remained throughout the experiment. Dominance of copepods or the absence of metazoan predators resulted in a mass appearance of bacterivorous protists (flagellates and ciliates). They promoted a fast decline of bacterial abundance and a shift to the predominance of morphologically inedible forms, mainly long filaments. After 3 days they formed 80-90% of the bacterial biomass. The results indicate that metazooplankton predation on phagotrophic protozoans is a key mechanism for the regulation of bacterioplankton density and community structure.

Species-specific algal responses to zooplankton: experimental and field observations in three nutrient-limited lakes

A series of 4-day manipulations of zooplankton biomass and nutrient availability was performed in enclosures in three lakes to determine species-specific algal responses to herbivory and nutrient enrichment. Algal performance in enclosures was compared to the relationships between weekly algal growth rates and the zooplankton in situ . When in situ growth rates were significant functions of zooplankton biomass, the responses were generally consistent with responses in the enclosure experiments. The importance of both nutrients and zooplankton in mediating algal growth was demonstrated by numerous observations: strong algal community response to enrichment, unimodal or positive responses of certain algal taxa to zooplankton biomass, differences in degree of nutrient limitation among the algal response types, lack of nutrient limitation of non-grazed algal taxa and a preponderance of taxa with no net response to increasing zooplankton biomass. Variation in the zooplankton community may be the largest source of variability in nutrient supply rate during summer in stratified lakes, and causes substational variability in the algae. Algae responded more strongly to changes in zooplankton composition than to changes in zooplankton biomass. We conclude that, due to the close coupling of phytoplankton and zooplankton communities in these nutrient-limited lakes, major compositional changes in the zooplankton have greater effects on the algae than do changes in biomass of grazers already present.

Seasonal changes in zooplankton composition in the Barents Sea, with special attention to Calanus spp. (Copepoda)

Seasonal changes in zooplankton composition in the Barents Sea, with special attention to <i>Calanus</i> spp. (Copepoda)

The Influence of Fish–Zooplankton–Phytoplankton Interactions on the Results of Selenium Toxicity Experiments Within Large Enclosures

The response of zooplankton to sodium selenite at concentrations of 1,10, and 100 μg Se∙L−1was studied using large (100 m3) enclosures in mercury-contaminated Clay Lake, Ontario (50°03′N, 90°30′W). Crustacean community development in treated enclosures exhibited no obvious acute or chronic effects from the range of selenium concentrations applied. Seasonal changes in zooplankton composition, abundance, and reproduction were similar among controls and the 1 and 10μg Se∙L−1enclosures. Differences in species dynamics observed in the 100 μg Se∙L−1enclosure and in a sediment control enclosure were attributable to biotic interactions rather than selenium. Predation appeared to be the dominant factor governing zooplankton community structure in all enclosures. Differences in the number of planktivorous fish among enclosures led to variations in the abundance of predatory Leptodora kindtii, which in turn affected abundances of the small cladoceran Bosmina longirostris.