Cladoceran Densities Research Articles

Revisiting zooplankton as indicators in the Great Lakes: Which indicators detect temporal changes in the zooplankton community composition?

Zooplankton are a vital component of the food web as the major conduit of energy from primary producers to planktivorous fishes. Therefore, changes in the structure of the zooplankton community affect how energy moves through aquatic ecosystems. Changes in the zooplankton community structure are typically documented through detailed community analysis, which can be difficult to interpret and communicate to non-experts. Alternatively, a few key summary indicators of community structure may better disseminate this information to a broader audience. In this study we analyzed zooplankton data from 1997 to 2019 from the US Environmental Protection Agency’s Great Lakes National Program Office to select indicators that summarized changes in the zooplankton community. Two indicators (percent of calanoids by biomass and areal density of herbivorous cladocerans) detected known changes in lakes Huron, Michigan, and Ontario, correlated with the crustacean zooplankton areal biomass above (herbivorous cladocerans) or in the hypolimnion (percent calanoids), and were related to the lake or basin-wide Carlson’s Trophic State Index based on chlorophyll (TSIchl) (percent calanoids by biomass). Our findings suggest that employing one or both selected indicators in addition to TSIchl and total crustacean zooplankton areal biomass, an already reported indicator in the Great Lakes that captures overall food availability for fish, would provide additional key information about zooplankton community structure in simple metrics that could be effectively communicated to stakeholders.

Impacts of hydrologic management on the eutrophication of shallow lakes in an intensive agricultural landscape (Saskatchewan, Canada)

Abstract Hydrologic management of shallow lakes is often undertaken to prevent fluctuations in lake level, and to ensure sufficient water volume for economic, domestic, and recreational uses, but there is inconsistent evidence of whether lake‐level stabilisation through hydrological management promotes or hinders eutrophication. Here we used multi‐proxy paleolimnological assessments of water quality (sedimentary carbon, nitrogen, total phosphorus, fossil pigments), and zooplankton community ecology (fossil Cladocera assemblages), combined with Landsat‐derived estimates of lake surface area in two shallow eutrophic lakes, in the Prairies of southern Saskatchewan, Canada, to quantify how 8 decades of contrasting hydrological management strategies (continuous or intermittent) affect primary production and phytoplankton composition. Analysis revealed that irregular hydrological management of Pelican Lake led to sharp increases in primary production concomitant with lake‐level decline. In contrast, continuously managed Buffalo Pound Lake, a drinking water reservoir for regional cities, exhibited slow, persistent eutrophication over decades despite active regulation of water levels. In both lakes, strong correlations of δ 15N values with pigments from diazotrophic cyanobacteria (canthaxanthin) showed that N2‐fixation increased during eutrophication irrespective of the timing of change. Finally, variation in fossil cladoceran density and composition reflected changes in pelagic and littoral habitats (e.g., reduced macrophyte cover) due to changes in both lake level and water quality. Basin comparison shows that while hydrologic management can moderate water quality degradation due to lake‐level change, it does not prevent eutrophication when nutrient influx remains high. Given that regional water availability is forecast to decline in coming decades, we anticipate that continued hydrological management will be unavoidable and will be unable to improve water quality unless nutrient influx is also controlled.

Experimental warming promotes CO2 uptake but hinders carbon incorporation toward higher trophic levels in cyanobacteria-dominated freshwater communities

Shallow freshwaters can exchange large amounts of carbon dioxide (CO2) with the atmosphere and also store significant quantities of carbon (C) in their sediments. Current warming and eutrophication pressures might alter the role of shallow freshwater ecosystems in the C cycle. Although eutrophication has been widely associated to an increase in total phytoplankton biomass and particularly of cyanobacteria, it is still poorly understood how warming may affect ecosystem metabolism under contrasting phytoplankton community composition. We studied the effects of experimental warming on CO2 fluxes and C allocation on two contrasting natural phytoplankton communities: chlorophytes-dominated versus cyanobacteria-dominated, both with a similar zooplankton community with a potentially high grazing capacity (i.e., standardized density of large-bodied cladocerans). The microcosms were subject to two different constant temperatures (control and +4 °C, i.e., 19.5 vs 23.5 °C) and we ensured no nutrient nor light limitation. CO2 uptake increased with warming in both communities, being the strongest in the cyanobacteria-dominated communities. However, only a comparatively minor share of the fixed C translated into increased phytoplankton (Chl-a), and particularly a negligible share translated into zooplankton biomass. Most C was either dissolved in the water (DIC) or sedimented, the latter being potentially available for mineralization into DIC and CO2, or methane (CH4) when anoxic conditions prevail. Our results suggest that C uptake increases with warming particularly when cyanobacteria dominate, however, due to the low efficiency in transfer through the trophic web the final fate of the fixed C may be substantially different in the long run.

Unraveling the potential of the green microalga, Monoraphidium littorale in rearing some copepods and cladocerans

The development of a feeding protocol of copepods and cladocerans is of paramount significance nowadays because they are considered nutritionally enriched live feeds for rearing numerous aquaculture species. Two experiments were conducted to evaluate the suitability of the green microalga Monoraphidium littorale on the population density and egg production of copepods (Diaptomus sp., Cyclops sp.) and cladocerans (Moina sp., Diaphanosoma sp.). In the first experiment, three diets including live M. littorale (T1), baker’s yeast (T2), and a combination of live M. littorale and baker’s yeast (T3) were fed to copepods and cladocerans for 10 days to determine the best feed. The results indicated that T1 was the best diet for the population density and egg production of Diaptomus sp. whereas T3 was best for Moina sp., Diaphanosoma sp., and Cyclops sp. In the second experiment, three concentrations of M. littorale including 1 × 105 cells mL−1 (T1), 5 × 105 cells mL−1 (T2), 10 × 105 cells mL−1 (T3), and dried powder of M. littorale (T4) were fed for 10 days to the copepods and cladocerans. T3 was found as the best diet for Diaptomus sp. where the mean maximum population density and egg production was significantly higher (P ˂ 0.05). Moina sp. exhibited the best growth and egg production both in T2 and T3; and Diaphanosoma sp. exhibited the best growth both in T2 and T4 but egg production in T2, T3 and T4. Interestingly, in case of Cyclops sp. the mean maximum population density and egg production were significantly higher (P ˂ 0.05) in T4 where powdered green microalgae M. littorale were used as feed. Based on the findings of the present research, M. littorale both in live and dried powdered form may be used as a suitable feed for the culture of copepods and cladocerans.

An exploration of Lake Ontario’s offshore epibenthic cladoceran community

Pelagic cladocerans are relatively well studied within the Great Lakes. However, little is known about cladocerans that more closely interact with benthic substrate. In 2018, 26 sites in Lake Ontario were sampled with benthic grabs to collect meiofauna. The stations ranged in depth from 0.1 to 184 m with sand, silt or hard bottom substrate. Epibenthic cladocerans were recovered from all 12 sites shallower than 20 m, five of eight sites between 20 and 40 m and one (63 m deep) of six sites deeper than 40 m. The density of epibenthic cladocerans were at most 12% of the density of harpacticoid copepods (shallow hard bottom sites). The Lake Ontario epibenthic cladoceran community was represented by 16 species from 8 different genera although one of these species, Illyocryptus cf. sordidus, is likely represented by two cryptic species. The most widespread species was identified as Alona sibirica (Sinev, 2020), a newly described species from Russia formerly of the Alona cf. affinis (Leydig, 1860) species complex. The Great Lakes specimens were 98.3% similar genetically to sequences assigned to A. cf. sibirica. Among substrates, sand had the highest densities (1662 m2 in 0–20 m) and species richness (10) of epibenthic Cladocera. After cladocerans were identified, the cytochrome oxidase I (COI) gene of 37 specimens were successfully sequenced through the Barcode of Life (BOLD). Six specimens were assigned to three previously existing Barcode Identification Numbers (BINs), the remaining 31 specimens were assigned to eight new BINs.

Effect of a glyphosate formulation on freshwater plankton: A community combined metric approach

Aim: The aim of this study was to experimentally assess the effects of glyphosate formulation on plankton composition by using different community parameters through a mesocosm experiment. Methodology: A 600 l mesocosm experiment was performed for 7 days, including a control (without glyphosate) and two concentrations of glyphosate. Results: Glyphosate caused a significant decrease in cladoceran density and a significant increase in rotifer, Chlorophyceae, and Euglenophyceae densities. In addition, zooplankton size diversity as well as microalgal evenness diminished. Interpretation: The decrease in cladoceran density may have benefited rotifers since they are less competitive for food resources. Moreover, the decrease in cladoceran foraging pressure over Chlorophyceae and Euglenophyceae may have benefited them. The different tolerances and competitiveness within the plankton components make the structure of this community a good indicator of environmental disturbance.

Physical and environmental drivers of oceanic manta ray Mobula birostris sightings at an aggregation site in Bahía de Banderas, Mexico

Oceanic manta raysMobula birostrisare distributed in tropical and subtropical oceans with aggregation sites typically at oceanic islands and seamounts. However, in some regions the species is found in coastal habitats close to highly productive areas. Recently, an important aggregation site for oceanic manta rays was identified along the southern coast of Bahía de Banderas, Mexico. We conducted weekly monitoring trips to the aggregation hotspots over a period of 4½ yr, recording manta sightings and collecting zooplankton samples, to investigate relationships between sightings and prey availability. We evaluated relationships between manta sightings and physical, biological, and environmental variables, finding a seasonal signal of manta occurrence with a peak in sightings around April, although there were substantial deviations from this trend in some years. Our results show effects of the El Niño Southern Oscillation on sighting rates, with more mantas during La Niña phases. We found significant relationships between manta sightings and sea surface temperature, moon phase, and tidal range. Manta sightings were negatively related to fish egg densities, positively related to copepod and cladoceran densities, and showed no relationship to euphausiid density. Mantas may be feeding on mesopelagic prey in the submarine canyon adjacent to the southern coast and basking in shallow waters through the day during thermal recovery periods. Identifying the seasonal patterns of occurrence and the environmental drivers of sightings will support the development of strategies to mitigate anthropogenic threats, which are common in this coastal population.

Functional groups of rotifers and an exotic species in a tropical shallow lake

In freshwater environments the rotifer group may be divided into microphagous and raptorial species regarding their feeding patterns, and such guilds differently interact with other community components. Here, we analyzed the influence of cladocerans, cyclopoid nauplii, temperature, food resources and an exotic species on rotifer guilds, based on weekly samplings for 1 year. We have identified rotifer species and their trophi types in order to separate them into the raptorial and microphagous functional groups. The ratio raptorial:microphagous rotifers (Guild ratio, GR) was used in interaction analyses with cladocerans, nauplii, temperature, food resources and the exotic species Kellicottia bostoniensis. Correlations between total rotifers and food (phytoplankton carbon) and temperature were negative and significant, therefore, these factors did not lead to the increase of rotifer community. On the other hand, microphagous rotifers had opposing relation to cladoceran densities, as GR values showed that they became predominant when cladoceran populations declined. The use of density-based GR was adequate, with similar results compared to biomass-based studies regarding interactions with other organisms. Furthermore, we have found no invasive characteristics for the exotic microphagous rotifer, Kellicottia bostoniensis, and it seems to be outcompeted by the native microphagous species.

鄱阳湖丰水期水位波动对浮游动物群落演替的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 鄱阳湖丰水期水位波动对浮游动物群落演替的影响 DOI: 10.5846/stxb201812142730 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31560133） Impact of water level fluctuations on the succession of zooplankton in Poyang lake Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了解鄱阳湖夏季丰水期水位剧烈波动过程中浮游动物的群落演替特征，2012年夏季鄱阳湖水位剧烈波动期间，于6月24日、7月7日和8月27日当水位下降且接近17.6 m时，在江西鄱阳湖国家级自然保护区内的1个浅水碟形湖泊设置4个采样点进行采样调查。共发现浮游动物65种，其中轮虫52种，枝角类7种，桡足类6种，多为营浮游生活的广温性和嗜温性种类。单因子方差分析（one-way ANOVA）显示3个月之间浮游动物的密度和生物量均具有显著差异（P<0.05），7月份浮游动物密度（1030.17±68.18个/L）显著高于6月份（325.16±41.60个/L）和8月份（203.79±24.91个/L）；6月份浮游动物的生物量（0.56±0.04 mg/L）显著低于7月份（1.22±0.11 mg/L）和8月份（0.99±0.11 mg/L）。基于浮游动物多度的聚类分析和自组织映射神经网络图均揭示夏季3个月份的浮游动物可区分为明显的3个群落：6月群落、7月群落和8月群落。蒙特卡罗检验发现水温、电导率、浊度和溶氧与浮游动物群落结构变化显著相关（P<0.05）。典型相关分析显示，6月份浮游动物群落与叶绿素a含量呈显著正相关关系，7月份浮游动物群落与水体温度呈显著正相关关系，8月份浮游动物群落与水深和电导率、浊度和溶氧呈显著正相关关系（P<0.05）。在3个月均为优势物种的盖氏精囊轮虫与叶绿素a含量呈正相关关系（P<0.05），与水温、pH、溶氧呈负相关（P<0.05）。夏季水位波动过程中浮游动物的群落结构在时间上（月份之间）发生明显演替，呈现轮虫密度逐渐降低，枝角类和桡足类密度逐渐增加的变化规律。水位波动引起环境因子的改变，从而对浮游动物的群落演替产生了重要影响。 Abstract:This study aims to understand the succession characteristics of zooplankton communities during dramatic water level fluctuations in Poyang Lake. During the drastic fluctuations in water levels of Poyang Lake in the summer, and on June 24, July 7 and August 27, 2012 when the water level dropped and approached 17.6 meters, four sampling points were established in a shallow dished sub-lake in Poyang Lake National Nature Reserve for the survey of zooplankton. A total of 65 species of zooplankton, including 52 species of rotifers, seven species of cladocerans and six species of copepods, were found during the study period. The zooplanktons were mostly the wide-temperature and mesophilic species of the planktonic type. The one-way analysis of variance revealed significant differences in zooplankton density and biomass within the three-month period (P<0.05). The density of zooplankton in July (1030.17 ±68.18 ind./L) was significantly higher, when compared to that in June (325.16 ±41.60 ind./L) and August (203.79 ±24.91 ind./L). Furthermore, the biomass of zooplankton in June (0.56 ±0.04 mg/L) was significantly lower than that in July (1.22 ±0.11 mg/L) and August (0.99 ±0.11 mg/L). The clustering of zooplankton communities by Bray-Curtis similarity measure and self-organizing maps revealed that the zooplankton was clearly divided into three communities:June community, July community, and August community. The Monte Carlo test revealed that water temperature, conductivity, turbidity and dissolved oxygen were significantly correlated with zooplankton community structure changes (P<0.05). The typical correlation analysis revealed that there was significantly positive correlation between zooplankton community and chlorophyll-a content in June. The water temperature and zooplankton community had a significant positive correlation in July. Furthermore, there were significant positive correlations between the zooplankton community and water depth, conductivity, turbidity and dissolved oxygen in August (P<0.05). Asplanchna girodi, which was the dominant species in the three-month period, was positively correlated with the chlorophyll-a content (P<0.05), but was negatively correlated with water temperature, pH and dissolved oxygen (P<0.05). The present study revealed that the zooplankton community structure exhibited a significant succession between months. Furthermore, the density of rotifers gradually decreased, and the density of cladocerans and copepods gradually increased. Moreover, the water level fluctuations caused changes in environmental factors, which had an important impact on the community succession of zooplankton. 参考文献 相似文献 引证文献

Influence of glacial flour on the primary and secondary production of sockeye salmon nursery lakes: a comparative modern and paleolimnological study

The increasing rate of glacier retreat and turbid glacial runoff can have a strong influence on freshwater ecosystems. Seton and Anderson lakes (British Columbia, Canada) are sockeye salmon (Oncorhynchus nerka) nursery systems. Since the 1940s, the Bridge River Diversion (BRD) introduced glacially turbid water into Seton Lake. To assess the impact of the BRD on the production of Seton Lake, we combined data from limnological surveys with the analysis of subfossil cladocerans and diatoms from sediment cores, using Anderson Lake as a reference. The modern data indicate that the euphotic zone is 14 m shallower and the cladoceran density and biomass are significantly lower in Seton Lake in comparison with Anderson Lake. The paleo-data indicate that following the BRD, the sedimentary fluxes of cladoceran and diatom declined 2- to 10-fold in Seton Lake and remained low thereafter. Together, our data support declines in primary and secondary producers following the BRD, likely due to changes in light penetration and (or) other indirect influence, and provides insights into the impact of turbid meltwater on the biological production of downstream lakes.

Assessment of larval fish assemblages and nursery habitat in the St. Clair River delta

The St. Clair River delta, part of the St. Clair-Detroit River System (SCDRS), is the most fished coastal wetland area in the Laurentian Great Lakes and provides nursery habitat for a variety of fish species; however, few large-scale surveys of larval fish have been performed within the delta since the 1980s. Larval fish, zooplankton, and aquatic plants were sampled at 20 sites from May through July in 2010 and 2011 to characterize shallow channel and backwater delta habitats used by fish. The larval fish assemblage was sampled using active and passive gears (conical nets and light traps) and was dominated by Cyprinidae, Catostomidae, and Gobiidae. The microzooplankton assemblage was composed of rotifers, copepod nauplii, and Dreissena spp. veligers, while the macrozooplankton assemblage was composed of mostly cyclopoids and harpacticoids in May and cladocerans later in the season. Scirpus spp. dominated the plant assemblage in June and was replaced by Chara spp. in July. Seasonal compositional shifts were evident for larval fish, zooplankton, and plant assemblages, and greater densities of microzooplankton and cladocerans were typically found in backwater areas. Assemblage compositions were comparable to those in historical surveys but invasive Gobiidae and Dreissena spp. veligers now represent substantial proportions of the larval fish and zooplankton assemblages, respectively. Due to the high connectivity and advective nature of the SCDRS, understanding the larval fish assemblage dynamics of the delta can help inform estimates of system productivity.

Invertebrate biodiversity in cold groundwater fissures in Iceland.

Iceland has an abundance of fissures that are parallel to the Mid‐Atlantic Ridge where bedrock cracks as a result of continental rifting. Some fissures penetrate the aquifer and expose the groundwater within the bedrock, becoming springs. As such, groundwater fissures have uniform and constant physical and chemical environment but they can differ greatly in morphology. In addition, there is often great variation in depth within fissures and substrate types contrast between vertical rock wall and more heterogenous horizontal bottom. The variation in morphological environment may create dissimilar habitats with unique characteristics and/or influence distribution of resources. Our objective was to study macrozoobenthos communities in cold groundwater fissures in Iceland in relation to physical habitat by comparing invertebrate diversity and density both between fissures with different morphological characteristics as well as between substrate types and depths within fissures. Samples were collected in two fissures in SW Iceland, Silfra and Flosagjá. Assemblages were similar between fissures except for higher densities of cladocerans in Flosagjá fissure. Within fissures, there was significant difference in Shannon diversity between substrate types in Flosagjá, and ostracods were found in significantly higher densities on the bottom. The distribution of all other taxa groups was homogenous in both fissures regardless of depth gradient and substrate. Invertebrates were found to be living within and around a biofilm that covered the entire substrate. These biofilm mats are made from Cyanobacteria and benthic diatoms, which are successful under low light conditions and may minimize any effect of the heterogeneous habitat creating a uniform and suitable microhabitat for invertebrates regardless of depth and substrate type.

Vertical change of cladoceran ephippial densities in the sediments of Lake Nanyi and its correlation with the nutrients

We examined the vertical variations of cladoceran ephippia in the sediments (1-28 cm) of Lake Nanyi. Nine cladoceran ephippia (Daphnia similoides sinensis, Daphnia galeata, Daphnia pulex, Ceriodaphnia sp., Moina micrura, Bosmina sp., Scapholeberis sp., Leydigia leydigii and Chydorus sp.) were identified. The ephippial densities of Daphnia species and small cladocerans ranged from 0 to 2.0 ind&middot;g-1 DM and from 0 to 10 ind&middot;g-1 DM, respectively. D. similoides sinensis and Ceriodaphnia sp. were respectively dominant species of large and small cladocerans in the sediments of Lake Nanyi. The ephippial densities of D. similoides sinensis had a significant negative correlation with total phosphorus content of sediments in the 1# sampling site of Lake Nanyi and had positive correlations with total nitrogen and total phosphorus contents in the 3# sampling site. In three sampling sites (except for total nitrogen contents in the 2# sampling site), there were significant positive relationships between the ephippial densities of Ceriodaphnia sp. and both total nitrogen and total phosphorus contents. Our results suggested that eutrophication and fish predation affected the historical succession of cladoceran community structure in Lake Nanyi.

Cladoceran abundance in relation to water quality parameters of Chakki Talab, Bodhan, Telangana

In the present study an attempt has been made to evaluate water quality and related density of Cladocerans for a period of one year, October 2015 to September 2016. Water quality parameters such as temperature, PH, total dissolved solids, dissolved oxygen, biological oxygen demand, total alkalinity, total hardness, chlorides, phosphates, and nitrates are presented here to relate with the abundance of Cladocerans. The Cladoceran abundance reflects the eutrophic nature of the Chakki talab.

Permafrost thaw lakes and ponds as habitats for abundant rotifer populations

Thermokarst lakes and ponds were sampled across a range of permafrost landscapes in subarctic Québec (Nunavik, Canada) to compare their rotifer and other zooplankton characteristics with a set of rock-basin lakes and ponds in the region. A total of 24 rotifer species were identified, with an average of seven taxa per waterbody. Rotifer abundance was an order of magnitude higher in the thaw ponds than in rock-basin waters. In some thaw ponds, rotifers accounted for &gt;50% of the total zooplankton biomass, but for &lt;10% in all of the rock-basin waters. Neither α- nor β-diversity was significantly different between the two waterbody types. Grazing experiments with microspheres (0.5–6 µm diameter) showed that medium-sized particles (2–3 µm) were preferred to smaller and larger particles; clearance rates were &lt;0.05% of the water column per day, implying that the rotifer populations were unlikely to be bottom-up limited by food availability. Rotifer abundance was negatively correlated with cladoceran densities, suggesting possible interference effects. Chaoborus larvae were also present and may exert a top-down control. Thermokarst ponds are currently favorable environments for rotifers, but the rapid change they have begun to experience brings uncertainty about their ongoing capacity to sustain these prolific communities.

汀棠湖轮虫主要食性功能群及其优势种群的周年动态对水环境变化的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 汀棠湖轮虫主要食性功能群及其优势种群的周年动态对水环境变化的响应 DOI: 10.5846/stxb201610232158 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（31470015）；安徽省高校自然科学研究重点项目（KJ2017A320）；重要生物资源的保护与利用安徽省重点实验室专项基金 Reponses of the annual dynamics of functional feeding groups and dominant populations of rotifers to environmental factors in Lake Tingtang Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探讨轻度富营养湖泊中轮虫主要食性功能群及其优势种群的动态对水环境响应的生态机理，于2011年7月至2012年6月每月4次采集了芜湖市汀棠湖水体中的浮游动物样品，同步测定了水温、水体透明度、pH值、水体叶绿素a含量和氮磷含量，利用相关分析和多元线性回归分析方法分析了轮虫主要食性功能群及其优势种群的密度与非生物因子（如水温等）、食物资源（以粒径大小不同的藻类中的叶绿素a含量作为指标）及生物因子（枝角类、桡足类和晶囊轮虫等轮虫潜在竞争者和捕食者的密度）间的关系。结果显示：（1）汀棠湖中，掠食性轮虫的优势轮虫为针簇多肢轮虫（Polyarthra trigla）；滤食性轮虫的优势种包括裂足臂尾轮虫（Brachionus diversicornis）、长三肢轮虫（Filinia longiseta）和裂痕龟纹轮虫（Anuraeopsis fissa）；（2）主成分分析表明，水温、叶绿素a含量、枝角类、桡足类及其无节幼体和晶囊轮虫的密度是影响与汀塘湖轮虫群落结构有关的变动最大的水环境因子。水温和藻类叶绿素a总含量分别对滤食性轮虫和掠食性轮虫总密度的周年变动的影响最大，而轮虫的潜在竞争者和捕食者对它们的负面影响均不大；（3）轮虫的潜在竞争者和捕食者对于轮虫优势种群密度动态的负面影响也不大。水温、藻类叶绿素a总含量及小型藻类叶绿素a含量（经孔径为25 μm的筛绢过滤后水样中的叶绿素a含量（Chl-a < 25 μm））均与滤食性裂足臂尾轮虫和长三肢轮虫的密度间呈现显著或极显著的正相关关系。仅小型藻类的叶绿素a含量对裂足臂尾轮虫和长三肢轮虫密度的周年变动的影响最大。水温是影响滤食性裂痕龟纹轮虫密度动态的主要因子；（4）两食性功能群中的优势轮虫种群的卵率均未与其潜在竞争者和捕食者密度间呈现显著的负相关性。裂足臂尾轮虫、长三肢轮虫和针簇多肢轮虫种群卵率的变动受水温的影响最大，且它们之间均分别呈现显著的负相关性。研究结果表明，水温和食物资源可能是影响汀塘湖中滤食性轮虫和掠食性轮虫密度变动的重要的生态因子。 Abstract:To study the ecological mechanisms underlying the responses of the functional feeding groups and dominant populations of rotifers to environmental factors in a slightly eutrophic lake, zooplankton samples were collected once weekly during July 2011 and June 2012 from Lake Tingtang, located in Wuhu City, Anhui Province, China. We also identified and analyzed annual variations in the density of each functional feeding group, the dominant populations, and the egg ratios of the dominant populations of rotifers. Simultaneously, physicochemical variables of water samples collected from Lake Tingtang, including water temperature, chlorophyll a (Chl-a) concentration, transparency, pH value, TN, NO3--N, NH4+-N, TP, and PO43- were measured. The Chl-a concentration in each water sample was measured in two fractions:one filtered through a 25 μm plankton net (Chl-a < 25 μm) and another unfiltered (Chl-a), which were used as biomass indicators of the algae with a smaller volume and all phytoplankton, respectively. On the basis of Pearson correlation and multiple linear regression analyses, the relationships between the densities of each rotifer functional group and dominant population and each of the environmental factors (abiotic factors, such as water temperature, food resources measured by the Chl-a concentrations of the algae with different cell volumes, and biotic variables of potential competitors, such as cladocerans and predators, including copepods and carnivorous Asplanchna rotifers) were analyzed. The main results were as follows. (1) Among the four dominant rotifer species occurring in Lake Tingtang, Polyarthra trigla was considered as a raptorial species, whereas Brachionus diversicornis, Anuraeopsis fissa, and Filinia longiseta were classed together as filter-feeding species. Suckers such as Trichocerca spp. were not considered in the present study because of their extremely low density. (2) Principal component analysis (PCA) showed that water temperature, Chl-a concentration, the densities of cladocerans, copepods and their nauplii, and Asplanchna were crucial for determining the dynamics of rotifer community structure in Lake Tingtang. Water temperature and Chl-a concentration of all phytoplankton was the most important factor shaping the annual dynamics of the filter-feeding and raptorial rotifers in Lake Tingtang, respectively. However, interspecific competition and predation pressure were not the key factors controlling the seasonal dynamics of any functional feeding groups. (3) Interspecific competition and predation pressure were also not the key factors affecting the annual dynamics of dominant populations of filter-feeders. Water temperature and the Chl-a concentration of algae with a smaller volume (Chl-a < 25 μm) were positively correlated with the densities of B. diversicornis and F. longiseta, classified as filter-feeders. Furthermore, the seasonal dynamics of B. diversicornis and F. longiseta were principally controlled by Chl-a < 25 μm. In comparison, the density of A. fissa was only affected by water temperature. (4) The egg ratios of filter-feeding rotifers, including B. diversicornis and F. longiseta, and the raptorial species P. trigla were mostly influenced by water temperature. Additionally, the egg ratios of three rotifers decreased with a decrease in water temperature. Taken together, the results indicate that water temperature and food resources are more likely to be the key factors affecting the annual dynamics of filter-feeding and raptorial rotifers than are the other examined variables, such as interspecific competition and predation pressure. 参考文献 相似文献 引证文献

Dormant Progagule Banks of Cladoceran Communites and Hatching Success from the Sedimentin China

The resources of cladoceran communitesin lakes in typical eutrophic shallow lakes in Chinawere investigated. Diapausing eggs of cladocerans were collected from the surface sediment of typical eutrophic shallow lakes and then hatched in the laboratory. The most common and dominant genera were Bosmina sp., Ceriodaphnia sp., Alona sp. and Moina sp. The density of large cladocerans in the hatchlings was lower than the small cladocerans (Bosmina, Ceriodaphnia, Alonaand Moina). The distribution and abundance and species of Daphnia community were significantly influenced by TN and fish community.

Search for Environmental Causation of the Cladoceran Dynamics in Lake Kinneret, Israel

Ten years of monthly dataset of cladoceran (Diaphanosoma sp., Bosmina spp., Ceriodaphnia spp.) density in Lake Kinneret (spatially scattered lake sampling stations), Israel, was studied with the aim of searching impact factors controlling their dynamics. Statistical regressions indicated that out of several environmental factors (among others, non-pyrrhophyte algal biomass, invertebrate predation) only temperature factor was relevant. Additional speculative assumptions of zooplanktivore fish predation suggest this factor as a significant impact on cladoceran dynamics.

Spatial and temporal variation of Cladocera in a tropical shallow lake

We studied cladoceran species richness, community composition, habitat preference and density in three spatial habitats over 1 year at Thale-Noi, a large shallow tropical lake in southern Thailand. Monthly sampling conducted with activity traps deployed overnight in littoral (Hydrilla and Ceratophyllum beds), open water (Hydrilla beds) and marginal zone (Utricularia beds), revealed that the macrophyte beds support similar cladoceran diversities regardless of the habitat. Total species richness in all studied habitats ranged between 30 and 34 species, supporting up to 22 species in a trapping area of 0.09 m2 at peak times, the majority belonging to the Chydoridae. In total, 40 species were recorded over the year, half of which were chydorids. Mixed cladoceran densities reached maxima of 160 333 ind.m−2 for a single habitat at a given moment. The dominant species included Chydoridae (Anthalona , Kurzia , Dunhevedia and Ephemeroporus ), Daphniidae (Ceriodaphnia ), Macrothricidae (Macrothrix ) and Ctenopoda (Latonopsis ). Monthly variation in species richness was most obvious in the littoral zone, whereas monthly variation in densities occurred at all sites. Community composition and habitat preference were mainly structured by depth and pH, resulting in different assemblages per habitat, but with uniform communities in the littoral (Hydrilla and Ceratophyllum ) beds in a single area. This study presents the first ecological survey of Cladocera using activity traps in a shallow tropical lake.

Enclosure experiment of effects of dietary phosphorus level on water quality, phosphorus budget, and plankton composition in intensive culture of crucian carp

Enclosure experiment was carried out to evaluate the effects of dietary phosphorus levels on water quality, phosphorus budget, and plankton composition in intensive culture of crucian carp (Carassius auratus). Monocalcium phosphate was used to formulate extruded feed containing total phosphorus of 8.7 (D1), 11.4 (D2), 13.5 (D3), and 18.4 (D4) g kg−1. Twelve polyethylene enclosures (each 4 × 4 × 1.5 m depth) were assigned to four groups with each one stocked with 120 juveniles (44.08 ± 1.36 g). Fish was fed twice daily at a rate of 3% body weight in the experiment. After 70 days of feeding, growth and survive rate of crucian carp were not affected by diet of different P level. It was found that physiochemical factors in all the enclosures did not show obvious threat on fish. Diets of different P level did not affect dissolved oxygen (DO), secchi depth (SD), total ammonium nitrogen (TAN), and total nitrogen (TN) concentration in enclosures. However, increased diet P level seemed to increase averaged pH, soluble reactive phosphorus (SRP), and total phosphorus (TP) concentration and decrease nitrite concentration and TN/TP. During later period of experiment, treatments with high diet P level (D3 and D4 treatments) had very high cyanobacterial biomass dominated by Microcystis spp., while phytoplankton in D1 and D2 treatments was mainly composed of edible algae. Composition and density of zooplankton in different treatments varied in similar pattern. Peak density of cladocerans (mainly Moina spp.) seemed to be related to diet P level. The present study indicated that changing P level in diets might bring complicated changes to the intensive crucian carp culture ecosystem.