Planktonic Structure Research Articles

Seasonal variations of plankton structure as bioindicators in Zayandehrud Dam Lake, Iran

Abstract Zayandehrud Dam Lake located in Isfahan province is the largest lake in central Iran. In this study, the plankton communities including phytoplankton and zooplankton were studied as bioindicator organisms for assessment of water quality in the Zayandehrud Dam Lake. The water and phytoplankton organisms were collected from four stations at different seasons during 2014 by using a Nansen bottle sampler. The zooplankton samples were collected with a plankton net (mesh size = 50 µm). The phytoplankton community was composed of Bacillariophyceae, Cyanophyceae, Euglenophyceae, Dinophyceae and Chrysophyceae. The zooplankton community viz; Cladocera, Rotifera and Copepoda were found to have a density range of 13–155, 21–141 and 11–93 (ind. m−3), respectively. In general, phytoplankton and zooplankton communities, especially the presence of genera such as Cyclotella, Dynobrion, Bosmina and Daphnia (as indices of oligotrophic lakes) and also absence of Microsystis, Brachionus and Lecane are seen as important indices of eutrophic lakes. It could be concluded that the Zayandehrud Dam Lake can be classified as a healthy water body.

Plankton Multiproxy Analyses in the Northern Patagonian Shelf, Argentina: Community Structure, Phycotoxins, and Characterization of Toxic Alexandrium Strains

The extensive Argentine continental shelf supports high plankton productivity and fish catches. In particular, El Rincon coastal area and the adjacent shelf fronts (38.5–42o S, 58.5–62o W) comprise diverse habitats and hold species of economic and ecological value. So far, studies of the microbial community at the base of the food web remain scarce. Here we describe the early spring plankton (>5-200 µm) structure in terms of abundance, biomass, species composition, functional groups and phycotoxin profiles in surface waters of El Rincon in September 2015. Diatoms were the most abundant and the largest contributors to carbon biomass at most stations. They dominated in coastal and inner-shelf (depths 20 µm) heterotrophic protists, e.g. various ciliates and dinoflagellates species were more abundant offshore. Scanning of phycotoxins in the field disclosed that paralytic shellfish poisoning (PSP) toxins were dominated by gonyautoxins-1/4 (GTX1/4). Lipophilic toxins were detected in low abundance, e.g. domoic acid (DA), although a bloom of Pseudo-nitzschia spp. (up to 3.6 x 105 cells L-1) was detected at inner-shelf stations. Pectenotoxin-2 (PTX-2) and 13-desmethyl spirolide C (SPX-1) were the most abundant in the field. PTX-2 co-occurred with Dinophysis spp., mainly D. tripos, while SPX-1 dominated at middle-shelf stations, where cells of Alexandrium catenella (1 strain) and A. ostenfeldii (3 strains) were isolated. The quantitative PSP profiles of the Alexandrium strains differed significantly from the field profiles. Moreover, the three A. ostenfeldii strains proved to be PSP producers and additionally produced 5 novel spirolides. Phylogenetic analyses of these first strains from the South Atlantic disclosed a new ribotype group suggesting a biogeographical distinction of the population. The plankton survey presented here contributes with baseline knowledge to evaluate potential ecosystem changes and to track the global distribution of toxigenic species.

Approaches for phosphorus removal with calcium hydroxide and floating macrophytes in a mesocosm experiment: impacts on plankton structure

Cultural eutrophication has promoted the application of several mitigation strategies in the last 50 years. In this study we tested the combined effects of two techniques: calcium hydroxide [(Ca(OH)2), lime] and a free-floating macrophyte (Salvinia rotundifolia Willd) to examine the soluble reactive phosphorus removal capability and the effects on plankton (phytoplankton and zooplankton) structure in a in situ lake mesocosms experiment. The experiment lasted 10 days (n = 12, 500 l each) with a control and three treatments (lime (CH), plants (FM), and the combination of both (CH + FM)). Samples of several physical and chemical variables (including nutrients) and phytoplankton were taken at the beginning, 2 days after, 4 days, and 10 days (end of the experiment). Zooplankton was sampled at the beginning and at the end. The highest depletion effect of soluble reactive phosphorus (SRP) was observed in presence of lime. Phytoplankton biovolume was highly and negatively affected in lime treatments (CH and CH + FM). Zooplankton changed from Rotifera to Cladocera and Copepoda in presence of macrophytes. We conclude that lime + plants reduces more effectively SRP, phytoplankton biovolume and promotes herbivorous zooplankton development; becoming by this way, in a suitable mitigation strategy to be explored in future field manipulation studies.

Shellfish culture: a complex driver of planktonic communities

AbstractThis review features recent updates on planktonic community alteration attributed to shellfish farming across three major drivers: predation, nutrient availability and the hydrodynamic environment. The grazing pressure generated by filter‐feeder communities (shellfish and epibionts) constitutes a ‘top‐down’ control of planktonic communities in aquaculture areas, inducing a significant depletion of planktonic organism concentration. By selecting larger cells during the filtration process, shellfish also favour smaller organisms in the water column, leading to the dominance of the latter. Direct excretion and the benthic alteration process tend to fertilise the water column and significantly stimulate primary production. The associated epibiont community particularly contributes to this regeneration process. The expected consequence of increasing nutrient availability is generally a planktonic shift in favour of small planktonic species. However, investigation on the relationship between planktonic structure and nutrient conditions has revealed a wide complexity and variability. Finally, all structures used in shellfish farming activities interact with water currents and tend to significantly increase the residence time of planktonic organisms inside shellfish farming areas. In grazing‐dominated systems, an increase in residence time tends to increase the exposure time of planktonic populations to detrimental conditions, reducing biomass and production. The general consequences of shellfish farming are a decrease in primary production in farming ecosystems, and a possible alteration of structure and functioning of planktonic communities. The implications of shellfish farming also appear to be quite different from other aquaculture activities such as fish farming, which tend to promote primary production leading to eutrophication process.

Preface to the Special Section: Dense Water Formations in the Northwestern Mediterranean: From the Physical Forcings to the Biogeochemical Consequences

AbstractThe northwestern Mediterranean Sea is one of the few sites of open‐sea deep convection and dense water formation. The area is characterized by intense air‐sea exchanges favored by the succession of strong northerly and northwesterly winds during autumn and winter that eventually induce deep convection episodes and the formation of the Western Mediterranean Deep Water. This region exhibits a significant spring phytoplankton bloom, which appears to be largely influenced in intensity and diversity by the winter mixing. To understand and resolve the interplay between the atmosphere and ocean, and the impact of ocean circulation and mixing on biogeochemistry, we carried out an unprecedented observational effort during a large experiment between July 2012 and July 2013. A multiplatform approach—combining aircraft, balloons, ships, moorings, floats, and gliders ‐ aimed both at characterizing the dynamics of the atmosphere and at quantifying the physical, biogeochemical, and biological properties of the water masses. Beyond a better understanding of the wind dynamics, the interannual variability of the deep convection, and the seasonal variability of the nutrient distribution and plankton structure in the pelagic ecosystem, the experiment provided a reference data set that was used as a benchmark for advancing the modeling of the surface fluxes, convective processes, dense water formation rates, and physical‐biogeochemical coupling processes. It also represented an opportunity for complementary investigations such as evaluating model parameterizations or studying the role of submesoscale eddies in dense water spreading and biogeochemistry.

Spatial variability and size structure of particles and plankton in the Fram Strait

Changes within marine pelagic fields in the Arctic affect global biogeochemical cycles. The size structure and distribution of particles and plankton (P&P) were studied in the main northward passage of Atlantic water to the Arctic region, which is affected in various ways by climate change. The wide size spectrum of P&P (3 µm–5 mm) was assessed by combining measurements from two complementary optical counters, a Laser In-Situ Scattering and Transmissometry (LISST) instrument and a Laser Optical Plankton Counter (LOPC). The measurements were performed in the upper 100 m layer at 55 stations in summer in 2013. The P&P were attributed to various functional groups – particles, phytoplankton, marine snow, and zooplankton – to test their spatial coupling with hydrodynamic forcing. Although our study confirms that the Fram Strait is a region of strong biophysical contrasts, the expected coastal-offshore gradient has not been distinguished clearly. Three mechanisms could explain P&P patches: particle flocculation due to contact with fresh waters from ice and fjords, enhanced production due to coastal upwelling as well as widening the range of warm surface water advection northwards. Particularly rich biological hot spots were recognised in the northern, shallow parts of the west Spitsbergen shelf, and near the marginal ice edges, confirming that these areas are highly vulnerable to marine predators. Moreover, combining optical measurements from two size-specific optical counters contributes greatly to reducing the substantial knowledge gap regarding wide size structure and distribution of thus far neglected seawater components, such as non-living particles and marine snow aggregates, occurring in this vulnerable Arctic region.

Hubungan Kelimpahan dan Keanekaragaman Fitoplankton dengan Kelimpahan dan Keanekaragaman Zooplankton di Perairan Pulau Serangan, Bali

Plankton is one of the biological resources that have an important role in the marine ecosystem. Plankton life is strongly influenced by the water quality parameters, one of which is the content of nutrients (nitrates and phosphates). Increased nutrient content caused by the increased load input from human activities. Serangan Island waters including the coastal ecosystem is widely used for a variety of human activities, such as tourism, aquaculture, residential, and transportation. All human activity will affect water quality will lead to an increase in nutrients and organic matter which in turn can lead to changes in water quality chemical physics and structure of plankton. The purpose of this study was to determine the relationship of the abundance and diversity of phytoplankton abundance and diversity of zooplankton and to know the physical parameters - chemical effect on the abundance of plankton. The method used is the Pearson correlation analysis to determine the relationship between abundance and diversity of phytoplankton abundance and diversity of zooplankton, and principal component analysis to look at the parameters of the water the most influence on the abundance of plankton. Results of Principal Component Analysis showed that the waters of the parameters that influence the abundance of plankton varies at each observation station. Pearson correlation analysis showed a strong relationship between the abundance of phytoplankton to zooplankton abundance with a correlation value of 0.64.

Large versus small zooplankton in relation to temperature in the Arctic shelf region

Climate change results in the alteration of the size structure of plankton, which consequently may affect higher trophic levels, such as planktivorous seabirds. In this study Laser Optical Plankton...

Zooplankton composition in four Reservoirs in Jos, Plateau State, Nigeria

The zooplankton community structure of four reservoirs (Kogingirin, Lamingo, Liberty and Tolemache) in Jos, Plateau State were studied for a period of two years (April 2012 to March 2014) using standard methods. The aim was to identify plankton structure as reference point for the sustainable management of the reservoirs for future developmental plan. The results identified four groups of zooplankton thus: Rotifera (59%), Cladocera (23%), Copepoda (14%) and Protozoan (4%). A total of 10 orders, 30 families and 130 species of zooplankton were collected across the reservoirs. Of this total, 22 species were common across the four reservoirs and 114 new species were identified. The order Ploimida was the most abundant while Brachionidae presented the highest number of family. Results obtained showed that reservoirs on the Plateau are highly resourceful in zooplankton. Keywords: Zooplankton Composition, Reservoirs, Order, Species, Families

Zooplankton composition in four reservoirs in Jos, Plateau State, Nigeria

The zooplankton community structure of four reservoirs (Kogingirin, Lamingo, Liberty and Tolemache) in Jos, Plateau State were studied for a period of two years (April 2012 to March 2014) using standard methods. The aim was to identify plankton structure as reference point for the sustainable management of the reservoirs for future developmental plan. The results identified four groups of zooplankton thus: Rotifera (59%), Cladocera (23%), Copepoda (14%) and Protozoan (4%). A total of 10 orders, 30 families and 130 species of zooplankton were collected across the reservoirs. Of this total, 22 species were common across the four reservoirs and 114 new species were identified. The order Ploimida was the most abundant while Brachionidae presented the highest number of family. Results obtained showed that reservoirs on the Plateau are highly resourceful in zooplankton. Keywords: Zooplankton Composition, Reservoirs, Order, Species, Families

Effect of eolian Fe-supply change on the phytoplankton productivity and community in central equatorial Pacific Ocean during the Pleistocene: A lipid biomarker approach

The effect of iron (Fe) fertilization on biological productivity and community structure in the equatorial Pacific, a region with high nutrient and low chlorophyll concentrations, has been debated for many years. Here we present lipid biomarker and geochemical proxy records in a sediment core from the central equatorial Pacific spanning from 1100 to 600ka to investigate the response of marine phytoplankton communities to eolian Fe supply and to assess links to environmental fluctuations during the Pleistocene. We found a strong link between change in eolian Fe input and phytoplankton community structure. Our data demonstrate that an increase in eolian Fe supply across the 800ka boundary resulted in a shift in the major primary producer from coccolithophores (alkenones) to diatoms (epi-brassicasterol) and dinoflagellates (dinosterol) at the study site. This strong link between changes in eolian Fe supply and the community structure of plankton during 800–600ka may have been associated with a change in atmospheric and ocean conditions due to southward migration of the Intertropical Convergence Zone (ITCZ). The lipid biomarker results show that such a high supply of eolian Fe might have led to a change in the dominant phytoplankton group. However, the opal record, which is often used asa primary productivity indicator, was not consistent with the biomarker results. Therefore, the results indicate that multi-proxy approaches should be used in paleoenvironmental studies because different proxies can reveal different aspects of environmental conditions, thus contributing to a better understanding of paleoceanographic conditions.

Distribusi Spasial Dan Struktur Komunitas Plankton Di Daerah Teluk Penerusan, Kabupaten Buleleng

Research spatial distribution and community structure of plankton in the Penerusan bay has been done on 22 February 2016.Plankton samples were taken at 17 stations using the Horizontal haul. The results obtained by the group of phytoplankton of the most widely found are from class Bacillariophyceae with the abundance of species composition percentage of 77% and the group most zooplankton were found came from class Maxillopoda with the percentage of the species composition of 85%. Highest abundance of phytoplankton found in abundance station 5, while the highest abundance of zooplankton found in abundance station 4. Index values diversity, uniformity and dominance of phytoplankton that is 1,06, 0.40 and 0.11 while the index value of diversity, uniformity and dominance zooplankton are 0.52,0.40 and 0.34. Results of the spatial distribution of phytoplankton abundance scattered in the middle of the bay towards the outside while the spatial distribution of zooplankton abundance spread from the south of the bay towards the middle of the bay and to the north of the bay Forwarding. Water quality in Penerusan Bay of physicists chemical parameters such as temperature obtained ranged from 31.1to 32,5 0C, average brightness obtained 87 %, turbidity obtained ranges between 0,73 to 2.62 ntu, dissolved oxygen (DO) obtained ranged from 6 to 8.3 mg/l , the degree of acidity (pH) obtained ranged from 7.17 to 8.04, salinity obtained ranged from 31-35 ppt, nitrate values obtained ranged from 0.60 to 1.83 mg/l and phosphate values obtained ranged from 0.10 to 0.78 mg/l.

Diversity and community structure of fish, plankton and benthos in Karangsong Mangrove Conservation Areas, Indramayu, West Java, Indonesia

Sihombing VS, Gunawan H, Sawitri R.2017. Diversity and community structure of fish, plankton and benthos in Karangsong Mangrove Conservation Areas, Indramayu, West Java, Indonesia. Biodiversitas 18: 601-608. The Karangsong Mangrove Conservation Area in Indramayu District, West Java, Indonesia, extending across 20 hectares of coastal land, has undergone eight years of managed revegetation. It has a variety of productive habitats that support the availability of fish resources. The research described in this paper was conducted in July 2016 with the purpose of assessing the diversity, evenness, and structure of fish, plankton and benthos communities as an indicator of the effectiveness of the rehabilitation of the mangrove ecosystem. The fish, benthos, and plankton were collected and analyzed in the Biotrop Laboratories. Fish sampling was carried out using a gill net with mesh size of 25 mm, and with traps. Juvenile fish were collected using a fish net with mesh size of 15 mm, by combing the water column horizontally for 10-15 minutes in the morning and afternoon. For plankton sampling a net No. 25 was used, while samples of benthos were collected using an Ekman Grab sampler. To calculate the community structure and diversity of fish, the study used ecological indices (abundance, dominance, constancy and ecological significance) and diversity indices (Shannon and Simpson diversity). A total of 413 individuals were obtained from 18 fish species, representing 16 families. Family Lutjanidae and Acanthuridae had the highest representative number of species and Pomacentridae showed the highest relative abundance of individuals. The value for the fish diversity index was 2.44 and for the species evenness index was 0.84. The fish population consisted of 44.44% omnivores, 38.89% carnivores and 16.67% herbivores/ detritivores. The highest density of plankton was accounted for by Bacillariophyceae (78.57%), followed by Chlorophyceae (14.29%) and Zooplankton (7.14%). The diversity index for the plankton (H) ranged between 1.040 and 1.462 across habitats, while the evenness index (E) ranged between 0.144 and 1.22. The benthos consisted of Gastropods (83.58%), Crustacea (3.28%), Palaemonidae (1.64%) and Oligochaeta (11.48%). The diversity index for the benthos ranged from 0. 939 to 1. 199 and the evenness index from 0.158 to 0.207. Hence, it may infer from the domination of the environment by Bacillariophyceae and Gastropods, and the low values for diversity index and evenness index, that the area is not particularly good as a fish nursery and breeding habitat. Nevertheless, there are two species of fish that exhibit potential productivity in every habitat; they are Chanos chanos and Scatophagus argus.

Evidence for Changes in Estuarine Zooplankton Fostered by Increased Climate Variance

Estuaries are among the most valuable aquatic systems in terms of their services to human welfare. They offer an ideal framework to assess multiscale processes linking climate and food web dynamics through the hydrological cycle. Resolving food web responses to climate change is fundamental to resilience management of these threatened ecosystems under global change scenarios. Here, we examined the temporal variability of the plankton food web in the Mondego Estuary, central Iberian Peninsula, over the period 2003 to 2012. The results pointed out a cascading effect from climate to plankton communities that follow a non-stationary behavior shaped by the climate variance envelope. Concurrent changes in hydrographic processes at the regional, that is, upwelling intensity, and local, that is, estuarine hydrology, scales were driven by climatic forcing promoted by the North Atlantic Oscillation; the influence of which permeated the physical environment in the estuary affecting both autotrophic and heterotrophic communities. The most conspicuous change arose around 2008 and consisted of an obvious decrease in freshwater taxa along with a noticeable increase in marine organisms, mainly driven by gelatinous zooplankton. The observed increase in small-sized cosmopolitan copepods, that is, Clausocalanus arcuicornis, Oithona plumifera, thermophilic species, that is, Penilia avirostris, and gelatinous zooplankton suggests a structural change in the Mondego plankton community. These results provide empirical support to the expectation that expanding climate variance changes plankton structure and functioning, likely fostering trophic interactions in pelagic food webs.

Significant Change in Marine Plankton Structure and Carbon Production After the Addition of River Water in a Mesocosm Experiment.

Rivers are known to be major contributors to eutrophication in marine coastal waters, but little is known on the short-term impact of freshwater surges on the structure and functioning of the marine plankton community. The effect of adding river water, reducing the salinity by 15 and 30%, on an autumn plankton community in a Mediterranean coastal lagoon (Thau Lagoon, France) was determined during a 6-day mesocosm experiment. Adding river water brought not only nutrients but also chlorophyceans that did not survive in the brackish mesocosm waters. The addition of water led to initial increases (days 1-2) in bacterial production as well as increases in the abundances of bacterioplankton and picoeukaryotes. After day 3, the increases were more significant for diatoms and dinoflagellates that were already present in the Thau Lagoon water (mainly Pseudo-nitzschia spp. group delicatissima and Prorocentrum triestinum) and other larger organisms (tintinnids, rotifers). At the same time, the abundances of bacterioplankton, cyanobacteria, and picoeukaryote fell, some nutrients (NH4+, SiO43-) returned to pre-input levels, and the plankton structure moved from a trophic food web based on secondary production to the accumulation of primary producers in the mesocosms with added river water. Our results also show that, after freshwater inputs, there is rapid emergence of plankton species that are potentially harmful to living organisms. This suggests that flash flood events may lead to sanitary issues, other than pathogens, in exploited marine areas.

Ecosystem changes in the Egyptian saline Lake Qarun during the XX–XXI centuries (short review)

Since beginning of the 20th century the salinity growth in Lake Qarun (Egypt) accelerated. Changes in the specific structure of plankton and benthos have been observed. Three stages of biotic changes may be separated. The salinity change determined biodiversity transformation only until 1928. Due to natural causes new species invasions – marginal marine (Cerastoderma glaucum, etc.) and halotolerant lacustrine (Arctodiaptomus salinus, Moina salina, etc.) – occurred, reducing the diversity and abundance of freshwater forms. Because of the growth of salinity the certain species of fish began to disappear in the lake. Catch of fish has fallen sharply, affecting the standard of living of the local population on the shores of the lake. To improve the situation, in 1928, people started to introduce the young marine fishes and crustaceans. Some species of introduced animals began to breed successfully, but not all, so the fry of some species of fish are transported annually from the sea into the lake. The second stage of the biotic transformation in the lake started, when the mass directed and accidental marine aquatic organism introduction by people was the main reason. The flow of marine species increased, halotolerant lacustrine species have disappeared, and the maritime community has formed. In 1950–1970s, intensive eutrophication began; it and alien species anthropogenic introduction have become the driving forces of the ecosystem changes. In the next decades, the main causes of changes in community structure will be eutrophication, pollution and aliens, especially jellyfish Mnemiopsis leidyi, invaded the lake in 2014.

The influence of nitrogen inputs on biomass and trophic structure of ocean plankton: a study using biomass and stable isotope size-spectra

Malaspina-2010 (CSD2008-00077) funded by program CONSOLIDER-INGENIO 2010; Ministerio de Ciencia e Innovacion (Spain), project EURO-BASIN (FP7-ENV-2010 264933) of the EU; Instituto Espanol de Oceanografia (IEO); PFPI (grant of IEO) to C.M.; FPU grant from the Spanish government (AP2010-5594) to B.F.-C.

The trophic role and impact of plankton ciliates in the microbial web structure of a tropical polymictic lake dominated by filamentous cyanobacteria

The recent interest in the plankton structures and dynamics in tropical and subtropical lakes has revealed important trends that set these lakes apart from temperate lakes, and one of the main differences is the enhanced importance of the microbial food web with respect to net plankton. Ciliates are a key component of subtropical and tropical microbial webs because of their role as dominant picoplankton grazers and their ability to channel picoplankton production to the uppermost trophic levels. Plankton ciliates have been found to play a crucial role in the survival of fish larvae in lakes that share several features with Lake Catemaco, a eutrophic tropical Mexican lake. Therefore, the plankton ciliate composition, abundance, and biomass of Lake Catemaco were studied to assess their role in the microbial food web. The data were obtained from surface and bottom water samples collected at eleven points during three surveys in 2011 and an additional survey in 2013, with the surveys covering the local climatic seasons. The most abundant components of the plankton ciliate assemblages were small prostomatids (<em>Urotricha </em>spp.), choreotrichs (<em>Rimostrombidium </em>spp.), cyclotrichs (<em>Mesodinium </em>and<em> Askenasia</em>), and scuticociliates (<em>Cyclidium, Cinetochilum, Pleuronema, </em>and <em>Uronema</em>). Other important ciliates in terms of abundance and/or biomass were haptorids (<em>Actinobolina, Belonophrya, Monodinium, Paradileptus, </em>and <em>Laginophrya</em>), <em>Halteria</em>, oligotrichs (<em>Limnostrombidium</em> and<em> Pelagostrombidium</em>), <em>Linostomella, Bursaridium, Cyrtolophosis,</em> and<em> Litonotus</em>. The ciliate abundance averaged 57 cells mL<sup>-1</sup> and ranged from 14 to 113 cells mL<sup>-1</sup>. The mean ciliate biomass was 71 µg C L<sup>-1</sup> and ranged from 10 to 202 µg C L<sup>-1</sup>. Differences were not detected in ciliate abundance or biomass between the sampling points or sampling depths (surface to bottom); however, significant differences were observed between seasons for both variables. Nano-sized filamentous cyanobacteria were the most abundant component of the plankton, and their abundance was assessed through epifluorescence microscopy counts. The autotrophic and heterotrophic picoplankton abundance was measured through epifluorescence, and their abundance and biomass were higher at the study site relative to other shallow freshwater ecosystems. The total ciliate biomass distribution patterns were similar to those of filamentous cyanobacteria and autotrophic or heterotrophic picoplankton, although the nanociliate biomasses peaked when the picoplankton and filamentous cyanobacteria were least abundant. The consequences of this increased importance of ciliates on the structure of the plankton at Lake Catemaco will be discussed along with the probable causes.

The community structure and seasonal dynamics of plankton in Bange Lake, northern Tibet, China

The seasonal variations in biomass, abundance, and species composition of plankton in relation to hydrography were studied in the saline Bange Lake, northern Tibet, China. Sampling was carried out between one to three times per month from May 2001 to July 2002. Salinity ranged from 14 to 146. The air and water temperature exhibited a clear seasonal pattern, and mean annual temperatures were approximately 4.8°C and 7.3°C, respectively. The lowest water temperature occurred in winter from December to March at -2°C and the highest in June and July at 17.7°C. Forty-one phytoplankton taxa, 21 zooplankton, and 5 benthic or facultative zooplankton were identified. The predominant phytoplankton species were Gloeothece linearis, Oscillatoria tenuis, Gloeocapsa punctata, Ctenocladus circinnatus, Dunaliella salina, and Spirulina major. The predominant zooplankton species included Holophrya actra, Brachionus plicatilis, Daphniopsis tibetana, Cletocamptus dertersi, and Arctodiaptomus salinus. The mean annual total phytoplankton density and biomass for the entire lake were 4.52×107 cells/L and 1.60 mg/L, respectively. The annual mean zooplankton abundance was 52, 162, 322, and 57, 144 ind./L, in the three sublakes. The annual mean total zooplankton biomass in Lakes 1–3 was 1.23, 9.98, and 2.13 mg/L, respectively. The annual mean tychoplankton abundances in Bg1, 2, and 3 were 47, 67, and 654 ind./L. The annual mean tychoplankton biomass was 2.36, 0.16, and 2.03 mg/L, respectively. The zooplankton biomass (including tychoplankton) in the lake was 9.11 mg/L. The total number of plankton species in the salt lake was significantly negatively correlated with salinity.

以临安东湖为例研究封闭性湖泊高温季节浮游生物的变化规律

本文通过调查临安东湖浮游生物及水质状况，鉴定并记录了浮游植物3门21属21种，其中蓝藻门7属，硅藻门6属，绿藻门8属。硅藻门中针杆藻属占整个藻类总数量的43.03%，在数量上占有绝对优势，弯形小尖头藻数量与微囊藻数量分别占藻类总数量的12.8%与12.6%。有害的藻类占据很高比例，说明水体呈现轻度污染的情况。浮游动物大多为萼花臂尾轮虫，其它浮游动物较少检测到，说明浮游动物的种类单一，多样性较差。水质指标中溶解氧含量较为正常，但水的PH值偏碱性，且夏季高温季节的氨氮含量偏高。在夏季温度最高的8月和9月，浮游植物总量达到峰值，而浮游动物总量则降至最低，这与水体中氨氮含量偏高有关。本研究分析了水域浮游生物数量结构特点，对水域环境进行了评价，并分析原因提出改善水域生态和环境的思路。 For investigating of the plankton community structure and water quality of Lin’an East Lake, 21 species of phytoplankton which belongs to 21 genera of 3 phylum were identified and recorded, including 7 genera of Cyanophyta, 6 genera of Bacillariophyta and 8 genera of Chlorophyta. Synedra genera accounted for 43.03% of the total number of algae and occupied the absolute superiority in quantity. Raphidiopsis eurtnta and Microcystis aeruginosa accounted for 12.8% and 12.6% of the total number of algae. Zooplanktons are mostly as Brachionus calyciflorus and other zooplankton is less detected, which indicates that the diversity of the species of zooplankton is poor. The dissolved oxygen content in water is relatively normal, but the PH value of water is slightly alkaline and the content of ammonia nitrogen is high during the summer season. This study characters the quantity and the structure of plankton and evaluates the water environment, and puts forward the idea of improving the ecological environment of East Lake.