8. The Effect of Bythotrephes Longimanus on the Size Structure of Zooplankton Communities in the Muskoka Region, Ontario

The characteristics of zooplankton communities and the relationships with the aquatic environment in the shallow waters of northern Liaodong Bay were investigated. Spot sampling surveys were carried out in April, June, September, and November 2018 to assess zooplankton species composition and diversity, abundance, biomass, and dominant species, and the associated relationships with environmental factors. A total of 45 species of zooplankton were recorded in the survey, comprising 18 Copepoda, 2 Amphipoda, 1 Mysidacea, 1 Decapoda, 1 Chaetognatha, 7 Hydrozoa, 1 Tunicate, and 14 planktonic larvae. Overall, the most dominant species was Aidanosagitta crassa (Tokioka, 1938), with copepods and planktonic larvae also dominating the zooplankton community. However, there was a seasonal alternation of species dominance. A cluster analysis showed that the zooplankton community in spring differed from other seasons and was mostly influenced by suspended particulate matter. Bioenv analysis indicated the main environmental factor affecting the zooplankton community in spring was suspended particulate matter. In summer, the determining variables were temperature, dissolved inorganic nitrogen (DIN), nitrate, and sediment pH. In autumn, temperature, DIN, and nitrate were determining variables, and dissolved oxygen (DO) and DIN in winter. Zooplankton abundance and biomass were influenced by salinity, suspended particulate matter, chemical oxygen demand (COD), chlorophyll, and water and sediment pH. In general, the shallow sea area north of Liaodong Bay is rich in zooplankton species and exhibits significant seasonal variations. Human activities have disturbed the biological community to a certain extent, and the environmental factors in this area are closely related to the diversity of zooplankton species.

To investigate relationships between crustacean zooplankton communities and lake morphometry we sampled 60 near-neutral Precambrian Shield lakes, including many small, shallow lakes. Morphometry-related patterns in the distributions of many zooplankton species were evident. Lake depth determined the occurrence of hypolimnetic species, and lake depth, lake area, and watershed area were positively related to the species richness of zooplankton communities. Among lakes with fish, deeper (maximum depth >8 m) lakes were characterized by greater species richness, higher abundances of a number of species including Daphnia pulex, Daphnia galeata mendotae, Daphnia dubia, and Diacyclops bicuspidatus thomasi, and lower abundances of Leptodiaptomus minutus, than shallower (maximum depth <8 m) lakes. Increased predation pressure by small fish species in smaller, shallower lakes probably influenced the observed species distributions. Lakes inferred to be fishless based on the presence of Chaoborus americanus typically had relatively high abundances of D. pulex, Diaphanosoma brachyurum, and Aglaodiaptomus leptopus, and absences of D. g. mendotae and D. birgei, patterns attributable to intense invertebrate predation on zooplankton.

Communities of coexisting organisms are formed by both dispersal among habitat patches in a region and local interactions within patches. The supply of colonists from the regional pool has the potential to alter the outcome of local interactions by providing species that fill different ecological roles. I examined the consequences of invasion by fish (juvenileLepomis macrochirus) and insect (Notonecta undulata) predators on experimental plankton communities that were either connected to or isolated from the regional pool of zooplankton species. The effects of predators on zooplankton composition and diversity depended on dispersal by members of the regional zooplankton species pool. Fish and notonectids reduced the abundance of large zooplankton and thereby facilitated invasion by new species from the surrounding region. Both predators reduced zooplankton species richness in the absence of dispersal, while fish had positive effects and notonectids had no effects with rapid dispersal. Fish facilitated invasion by more species than they excluded, while similar numbers of species invaded with notonectids as were driven extinct. The effects of predators on planktonic trophic structure (zooplankton size structure and biomass, phytoplankton biomass) were independent of the level of dispersal. Both predators reduced zooplankton mean body size, but only fish enhanced phytoplankton density. Invasion by members of the regional species pool slightly increased zooplankton mean body size and reduced phytoplankton biomass; however, the effects were small and independent of the predator treatment. Predator-facilitated invasion of new species altered the effects of predators on zooplankton species composition and diversity, but not on plankton trophic structure. The results suggest that spatial heterogeneity in predator abundance promotes regional coexistence among zooplankton. Connection to a diverse regional species pool via dispersal may therefore be important for determining the impact of local interactions such as predation on communities.

Effects of filter-feeding planktivorous fish and cyanobacteria on structuring the zooplankton community in the eastern plain lakes of China

Predators can strongly affect prey communities, but their influence may be difficult to distinguish from bottom‐up and other environmental effects. The problem of assessing predator impact is especially difficult in large systems that do not allow for comparisons across multiple units (e.g., small lakes) that have varying predator density. For instance, the invasion of the predatory zooplankter, Bythotrephes longimanus, into the Laurentian Great Lakes contributed to the nearly complete disappearance of several zooplankton species, but current effects on extant zooplankton are not well understood. We used generalized additive models (GAMs) applied to long‐term data time series (1994–2012) to examine B. longimanus effects on zooplankton species in Lake Michigan. Because B. longimanus abundance varied over time, our approach allowed assessment of predator effects from field data while accounting for other factors, including food resources, temperature, and seasonality. Results suggest that B. longimanus substantially reduces some zooplankton population growth rates, with the largest effects on species that B. longimanus affected more strongly in experiments. For example, at maximum B. longimanus abundance, Daphnia mendotae, Bosmina longirostris, and Diacyclops thomasi population growth rates were estimated to be reduced by 17%, 30%, and 21%, respectively, compared to no effect on calanoid copepods. Results further indicated positive temperature effects on population growth that differed by species. Our study thus provides field‐based evidence for ongoing impacts of invasive species and temperature on zooplankton production and composition, with potential consequences for planktivorous fish, and exemplifies how GAMs can be used to determine predator effects from time series data.

Several zooplankton species are susceptible to ultraviolet radiation (UV), suggesting that UV may shape zooplankton community composition. Little is known, however, about the quantitative effects of long-term UV exposure in relation to biological processes. Therefore, we studied effects of UV on behaviour, population dynamics and reproduction of several zooplankton taxa. We identified different strategies regarding daytime vertical distribution: a strong response to UV threat, illustrated by Daphnia; a weak, albeit significant response, such as in copepods; and lastly, a stationary position in a depth refuge, as in Chydorus and Eurycercus. The relative abundances of the different zooplankton species were similar and only Daphnia and copepod nauplii displayed a slight decrease in relative abundance in response to UV treatment. Daphnia also reacted to the UV threat by increasing resting egg production, whereas long-term population dynamics for all studied species were surprisingly similar between treatments, despite considerable differences in UV exposure for several months. We conclude that zooplankton communities at temperate latitudes are able to survive increased UV levels due to efficient defences, suggesting that future potential increases in UV radiation may result in only moderate impacts on zooplankton population dynamics and community composition.

Seasonal variations in zooplankton abundance, biomass, species diversity and community structure were investigated in the Sanmen Bay, China. Samples were collected from 15 stations, on the seasonal basis, in April (spring), July (summer) and October 2005 (autumn) and January 2006 (winter), respectively. The results show that zooplankton species number, abundance and biomass varied widely and had distinct spatial heterogeneity in the Sanmen Bay. A total of 72 species of zooplankton belonging to 56 genera and 17 groups of pelagic larvae were identified. The zooplankton species richness was strongly related to salinity. Based on hierarchical cluster analysis, zooplankton in this study area were classified into three groups: coastal, neritic and pelagic groups, which corresponded to the upper, middle and lower portion of the Sanmen Bay, respectively. The coastal low-saline species were dominant in the study area. The zooplankton abundance and biomass reached a peak in summer, moderate in spring and autumn, and the lowest in winter. Zooplankton abundance decreased from the upper to lower portion of the bay in April, when the highest biomass occurred in the middle portion of the bay. There were the same spatial distribution patterns for the biomass and abundance in July, with the maximum in the middle of the bay. However, zooplankton abundance was the highest in the middle of the bay in October, when maximum biomass occurred near the lower of the bay. Zooplankton abundance and biomass were evenly distributed in the Sanmen Bay in January. Spatial and temporal variations in zooplankton and their relationship with environmental factors were also analyzed. The BIOENV results indicate that the combination of chlorophyll a (Chl-a), salinity, dissolved inorganic nitrogen (DIN), dissolved oxygen (DO) and silicate (SiO3) was responsible for the variations in zooplankton community structure in the Sanmen Bay. The environmental changes played an important role in changes in the zooplankton community structure in the Sanmen Bay.

PDF HTML阅读 XML下载 导出引用 引用提醒 不同类型景观水体浮游动物群落差异及其影响因素 DOI: 10.5846/stxb201904020638 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 2013年度上海市政府发展研究中心——上海师范大学研究基地专项课题（2013-YJ-C08）；中国博士后科学基金（2019M661574） Characteristics of zooplankton community in different types of landscape waters and their influencing factors 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:探明不同类型景观水体中环境敏感型浮游动物群落特征差异及影响因素对景观水体生物多样性维持和水生生态系统保护十分重要。于2014年5月在上海选取具代表性的8个景观水体共设置35个采样点进行浮游动物采样调查，并同步测定水体环境指标。本次调查采集并鉴定浮游动物40种，其中轮虫29种，枝角类7种，桡足类4种。基于浮游动物群落组成进行聚类分析，所有采样点聚为四种景观类型：天然湖泊（淀山湖）、人工湖泊（滴水湖）、AAAA级公园水体（共青森林公园和古猗园）和普通综合性公园水体（世纪公园、和平公园、长风公园和车镜公园）。两种公园水体浮游动物种类较为丰富，多样性较高，各自约有40%的种为生境特有种，而淀山湖特有种仅1种（为猛水蚤），滴水湖3种均为蛭态类。物种相似性方面，大型天然淀山湖与人工滴水湖相似性最高（37.5%），普通公园水体次之（33.3%），与AAAA公园水体相似度最低（20%）。后两者间的相似性较高（27.8%），且两者与滴水湖的相似度均较低（18.5%和12.0%）。四类水体仅有3个共有种/类群：角突臂尾轮虫（Brachionus angularis）、螺形龟甲轮虫（Keratella cochlearis）和桡足类无节幼体。AAAA公园水体中甲壳纲动物的相对丰度（88.8%）远高于其他水体，其优势种由3种大型浮游动物（甲壳纲）组成，普通公园水体优势种仅由4种小型浮游动物（轮虫）组成，淀山湖和滴水湖的群落结构简单，优势种单一。冗余分析（RDA）显示，水温、透明度、pH、化学需氧量、氨氮和总磷是影响景观水体浮游动物群落差异的显著环境因子。 Abstract:Identifying the differences in environment-sensitive zooplankton community characteristics and influencing factors among different types of landscape waters is critical for maintenance of biodiversity and protection of aquatic ecosystem. Zooplankton was sampled from 35 sites in 8 typical landscape waters in Shanghai and in situ physicochemical variables were measured in May 2014. A total of 40 species of zooplankton were recorded in the study area, of which 29 species were recorded as Rotifera, 7 species as Cladocera, and only 4 of them as Copepoda. Cluster analysis showed the zooplankton communities in all sampling sites were clustered into four groups:natural fresh-water lake (Lake Dianshan), man-made lake (Lake Dishui), waters in AAAA grade parks (Gongqing Forest Park and Guyiyuan Park), and waters in ordinary comprehensive parks (Century Park, Heping Park, Changfeng Park, and Chejing Park). Zooplankton species in the two types of park were richer, of which about 40% were endemic species. While there was only 1 endemic species (Harpacticoida) in Lake Dianshan, and three endemic species (Bdelloidea) in Lake Dishui. In terms of species similarity, the natural Lake Dianshan had the highest similarity (37.5%) with the man-made Lake Dishui, followed by ordinary parks (33.3%), and AAAA grade parks (20%). The species similarity between the latter two was higher (27.8%), while Lake Dishui had a lower similarity with the latter two (18.5% and 12.0%). There were only three taxa (Brachionus angularis, Keratella cochlearis and Copepoda nauplii) detected in all types of waters. The relative abundance of crustaceans in waters of AAAA grade park (88.8%) was much higher than that in other waters. The dominant species in waters of AAAA grade parks were composed of three large-size zooplankton species (crustaceans). The dominant species in waters of ordinary comprehensive parks were composed of four small-sized zooplankton species (rotifers). The community structures in both Lake Dianshan and Lake Dishui were simple. Redundancy analysis showed water temperature, transparency, pH, and chemical oxygen demand were significant factors affecting zooplankton community structure in landscape waters. 参考文献 相似文献 引证文献

Deforestation of riparian areas is a major driver of biodiversity loss in aquatic ecosystems. Thus, we investigated the influence of forest cover and physical and chemical characteristics of streams on zooplankton communities in the southeastern Amazon. We addressed the following questions: (1) Are environmental factors (water physical and chemical characteristics and landscape variables) and dispersive processes (reflected in the spatial structure among sampling sites) efficient predictors of zooplankton communities in different hydrologic seasons? (2) Can zooplankton species be indicators of watersheds’ forest-cover levels? We sampled 15 streams located in nine rural settlements in northern Mato Grosso, Brazil, in the dry (August) and rainy (March) seasons of 2017. The forest-cover level had a significant effect on the physical and chemical characteristics (conductivity, dissolved oxygen, and temperature) of streams and also on the structure and composition of zooplankton communities, mainly of rotifers and testate amoebae. Areas with low vegetation cover had seasonal changes in species richness, individuals density, and zooplankton community structure. Environmental and spatial variables had no significant effect on the structure of zooplankton communities, which may indicate the strong influence of stochastic factors. Species from three zooplankton groups (rotifers, microcrustaceans, and testate amoebae) were indicators of forest-cover classes. This study provided valuable contributions to the conservation of riparian ecosystems and the use of biological indicators in environmental monitoring programs.

Assessment of aquatic ecological health: A comparative study between cistern-made and ‘Natural’ earthen-made waterbody

Invasive predators are a large and growing threat to species diversity and human well-being. One of the reasons invasive predators have a negative impact is that native prey species do not possess appropriate anti-predator defenses. However, rapid evolution may allow prey species to respond adaptively to introduced predators. When this occurs the impacts of invasive predators are mitigated. An invasive predator that is of concern in North America is the spiny water flea, Bythotrephes longimanus. It disrupts freshwater ecosystems through voracious consumption of zooplankton. Declines in zooplankton abundance and richness reduce water quality and recreational fishing opportunities. However, a species of zooplankton, Daphnia mendotae has been found to adaptively respond to B. longimanus. This adaptation is diel vertical migration, the behavioral change of occupying a lower position in the water column during the day to reduce predation risk. Despite the ecological and economic implications of this behavior in response to B. longimanus, it has only been studied in a few lakes. This study investigated adaptive diel vertical migration in D. mendotae from multiple lakes. This was done by measuring the vertical position of D. mendotae in artificial water columns. It was hypothesized that D. mendotae from lakes that have been invaded by B. longimanus will exhibit diel vertical migration in the presence of B. longimanus. If this hypothesis is supported, rapid evolution of diel vertical migration can be established as a widespread response. This would strengthen understanding of rapid evolution and allow lakes more vulnerable to B.longimanus to be identified.

Summary A dataset of 1735 Norwegian lakes, spanning a wide range of geographical, physical, chemical and biological properties, was analysed to assess the role of the top invertebrate predator, Bythotrephes longimanus, on the crustacean species richness and community structure. Bythotrephes was associated with a 25.5% increase in mean richness of other zooplankton species, and this effect could not be related to confounding factors. Based on presence–absence data, community composition did not differ significantly between lakes with and without this top predator. Neither fish predation nor lake area, altitude, and geographical or physicochemical parameters offer any obvious impact on the observed diversity patterns. We suggest that Bythotrephes facilitates species richness by reducing the abundance of species controlling subdominant species. This pattern of increased diversity offers an interesting contrast to North American lakes recently invaded by Bythotrephes, where species richness typically has decreased, suggesting different short‐term and long‐term effects of predatory invaders.

Aim This study aimed to answer: (i) can phytoplankton communities be used as surrogate of zooplankton communities?; (ii) can we use ecological approaches like functional groups (FG) or morphofunctional classification (MBFG) as surrogate for phytoplankton species?; (iii) can we use substitute groups (cladocera, copepod, rotifer or testate amoebae) as surrogate for zooplankton species?; (iv) are the environmental variables’ ordination standards concordant with the ordering patterns of phytoplankton and zooplankton species?; and (v) for both communities, is the spatial pattern of ordination maintained using density data or presence/absence of individuals or lower taxonomic resolutions? Methods The study was conducted in 25 water bodies that supply central-pivot irrigation in the Federal District - Brazil (Rio Preto Basin), in October 2012. We evaluated some physical and chemical variables as well as phytoplankton and zooplankton samples. To evaluate correlation among biological groups, numerical and higher taxonomic resolutions, we performed some Mantel and Procrustes analyses. Results Evaluating the use of substitute groups, comparisons between phytoplankton and zooplankton, FG and MBFG classifications and almost all the comparisons between zooplankton groups suggested concordant patterns. However, the values of r were low, all below 0.70. Biological analyses with phytoplankton and zooplankton can be performed using presence/absence of individuals without significant loss of information, except for MBFG classification and copepods. Data may also be used at genus or family level for copepods and testate amoebae and only data at genus level for cladocerans and rotifers. Different results were found concerning taxonomic resolution for phytoplankton considering that, while being significant, the r value was less than 0.70. Conclusions For environmental monitoring purposes, it is important to sample both phytoplankton and zooplankton communities because one is not surrogate of the other one, in the same way as phytoplankton density and their functional and morphofunctional approaches. On the other hand, to simplify the environmental monitoring, it is possible to adopt presence/absence species data instead of abundance data for both zooplankton and phytoplankton communities, except for copepods and morphofunctional approach. It is also possible to adopt genera level for zooplankton community and family level for copepods and testate amoebae.

The introduction and extirpation of predators can have large impacts on food web structure and ecosystem function. The magnitude of these predator effects can be influenced by species diversity and turnover along environmental gradients in space or time, which have the potential to buffer or magnify the impact of trophic interactions on ecosystem functioning. In this study, we explored the individual species and community effects of fish predators on lake zooplankton in the Sierra Nevada, CA, USA. Local and beta diversity in zooplankton communities were resilient to fish, only marginally differing among fish and fishless sites, and were more structured along elevational gradients. Observed diversity changes were attributed to species turnover in zooplankton communities, which suggests elevational gradients and fish are acting as ecological filters excluding subsets of species rather than reducing species density. We found that fish significantly reduced densities of larger‐bodied zooplankton species. Further, as larger‐bodied species densities were lower in the presence of fish, we found that the community weighted mean of body mass decreased in the presence of fish in lakes. Although species turnover largely maintained diversity over elevational gradients and in the presence of fish, such changes in larger‐bodied taxa and community biomass may have important implications in the transfer of energy throughout the food web and to connected riparian and aquatic ecosystems that are dependent on the flow of biomass and nutrients.

We studied the spatial and temporal variation in relative abundance (CPUE), habitat use, and diet of Arctic charr (Salvelinus alpinus (L.)) and brown trout (Salmo trutta L.) in Lake Atnsjoen in southern Norway over a period of 14 years (1985–1998). Fish were sampled with gill nets in epibenthic and pelagic habitats in August each year. Stratified sampling in the epibenthic habitat was carried out with gill net series at three depth zones (0–10, 10–30 and 30–70 m) at one station (1985–1993), and at seven depth zones between 0–3 m and 50–70 m at 10 different stations with multi-mesh gill nets (1994–1998). Lake Atnsjoen is a relatively deep (maximum 80 m), unregulated, subalpine, oligotrophic lake which is not affected to any extent by local or long-range pollution. In shallow epibenthic areas, brown trout is the most abundant species, while Arctic charr dominate deeper epibenthic areas. Epibenthic catches of brown trout at 0–10 m depth were inversely correlated with the catches of Arctic charr. The catches of epibenthic brown trout and Arctic charr did not correlate with mean water temperature in the sampling period. In the pelagic zone, brown trout were mainly caught close to the surface (0–6 m), while Arctic charr were caught between the surface and 12 m depth. Pelagic fish of both species were significantly larger than individuals caught in the epibenthic habitat. The mean size of epibenthic brown trout increased with depth. The opposite trend was evident for Arctic charr, although some larger fish also occupy deeper areas. The size of brown trout in epibenthic areas correlated inversely with CPUE, while no such relationship existed for Arctic charr. The most important food items for Arctic charr in both habitats in August were various species of zooplankton; Daphnia longispina, Bosmina longispina, Bythotrephes longimanus and Polyphemus pediculus. Brown trout mainly foraged near the surface on insects in both habitats, but B. longimanus and P. pediculus were preyed upon to some extent by pelagic specimens. The number of piscivorous individuals was low in both species (1.9–4.5%).