Crustacean Zooplankton Species Richness Research Articles

Crustacean zooplankton communities in Chiloé Island coastal lakes (42°S, Chile)

The lakes of Chiloé Island have a high dissolved organic carbon concentration (known as “humic”) and show a connection with brackish water. They also display a high species richness of crustacean zooplankton. The aim of the present study is to characterize the potential factors that explain crustacean species richness in Chiloé Island lakes. To that purpose parameters of the abiotic environment were determined. The results of PCA performed on those data revealed the existence of three lakes with high crustacean species richness that are relatively deep, show high nitrogen concentrations, and are located at relatively high altitude. In contrast, there are two lakes with low species richness, high mineral concentration, and situated at low altitude. One of these lowland lakes gives rise to a river effluent to the sea, and it is connected to the other lake; these observations agree with the results of a performed cluster analysis. Nevertheless, the co-occurrence null model analysis revealed the absence of regulator patterns in species associations, which could be explained to the fact that many of the species occur in most of the lakes. These results are markedly different in comparison to Patagonian lakes of Argentina and Chile that have a low crustacean species number.

Species richness of crustacean zooplankton and trophic structure of brackish lagoons in contrasting climate zones: north temperate Denmark and Mediterranean Catalonia (Spain)

We sought to identify environmental factors influencing crustacean zooplankton species richness in brackish lagoons and to elucidate whether crustacean zooplankton species richness and trophic structure of brackish lagoons differ among two regions with contrasting temperatures. We sampled 35 and 42 brackish lagoons (salinity ranging from 0.3 to 55‰) in Mediterranean Catalonia (NE Spain) and northern‐temperate Denmark, respectively. No significant differences were found in total crustacean zooplankton species richness or cladoceran richness between the climatic regions. Calanoid richness was higher in Denmark than in Catalonia, while cyclopoid richness was higher in Catalonia. Salinity was the most important variable associated with zooplankton species richness in both regions, richness of total zooplankton species, cladocerans and cyclopoids being negatively related with salinity. In both regions, a shift occurred from dominance of large filter feeding cladoceran species at low salinities to copepods and small cladoceran species at higher salinities. Cladoceran richness increased with increasing total phosphorus, but was not influenced by total nitrogen or chlorophyll‐a. Trophic structure in Mediterranean brackish lagoons showed a more pronounced seasonal variation than in north temperate brackish lagoons. Our results imply that the indirect effects of climate warming, such as changes in salinity and hydrology, will have a larger impact on brackish lagoon ecosystems than the increase in temperature per se.

The relationship between zooplankton community structure and lake characteristics in temperate lakes (Northern Wisconsin, USA)

Zooplankton community structure can be affected by within-lake and by watershed ecological factors, including water chemistry (related to landscape position), lake morphology and human activity in the watershed. We hypothesized that all three groups of drivers would be correlated with zooplankton species richness and species composition for lakes in northern Wisconsin. Data collected from 52 lakes allowed us to explore the relationship of zooplankton community structure with ecological drivers. We found that crustacean zooplankton species richness was not significantly correlated with independent environmental variables derived from PCA ordination, nor with measures of community structure based on NMS ordination. However, species composition was correlated with environmental gradients. Larger zooplankton species (Daphnia pulicaria, Epischura lacustris, Skistodiaptomus oregonensis, Mesocyclops americanus) occurred in large and deep lakes low in the landscape gradient, whereas the smaller species Ceriodaphnia dubia, Daphnia retrocurva and Leptodiaptomus minutus tended to occur high in the landscape. This shift in species composition was correlated with increased conductivity, primary productivity and the hypolimnetic refuges characteristic of larger deeper lakes lower in the landscape. Riparian housing development and littoral zone habitat (measured as building density and by abundance of logs in littoral zones) were not correlated with zooplankton community structure. In these relatively low-impact lakes, natural drivers are still the most significant determinants of zooplankton community structure.

Crustacean zooplankton species richness and productivity: to what extent do the conclusions depend upon the choice of metrics?

The form of the relationship between productivity and diversity is the subject of much debate. In studies that compare among site variations in species richness, the relationship varies with taxonomic grouping, spatial scale, productivity range, predation pressure and community assembly. However, direct measurements of productivity are often lacking, necessitating the use of proxies. Nutrient concentrations and algal biomass have both been used as such productivity metrics in studies of freshwaters, but no studies have compared explicitly the form of the richness–productivity relationship when different proxies are used in the same study. Furthermore, different studies use species richness data collected over different time periods, ranging from a single day to many years. In this study the relationship between crustacean zooplankton species richness and productivity is examined, using four metrics of productivity and three temporal scales. The productivity metrics differed in their ability to statistically explain variations in species richness, with concentrations of soluble reactive phosphorus and chlorophyll a being the most powerful predictors. However, the form of the productivity–richness relationship differed in each case, being linear in the former analysis and quadratic in the latter. Comparison of analyses based on species data from different time periods, revealed that the magnitude of the productivity effect was greatest for long‐term species richness and smallest for the richness determined on a single sampling occasion. The proportion of the total species pool that was present on any one sampling date was itself dependent on productivity. Differences in the definition of both productivity and species richness can cause variability in the form of the relationship between the two. This may then confound comparisons between studies that use different methodologies.

Crustacean zooplankton species richness and productivity: to what extent do the conclusions depend upon the choice of metrics?

The form of the relationship between productivity and diversity is the subject of much debate. In studies that compare among site variations in species richness, the relationship varies with taxonomic grouping, spatial scale, productivity range, predation pressure and community assembly. However, direct measurements of productivity are often lacking, necessitating the use of proxies. Nutrient concentrations and algal biomass have both been used as such productivity metrics in studies of freshwaters, but no studies have compared explicitly the form of the richness–productivity relationship when different proxies are used in the same study. Furthermore, different studies use species richness data collected over different time periods, ranging from a single day to many years. In this study the relationship between crustacean zooplankton species richness and productivity is examined, using four metrics of productivity and three temporal scales. The productivity metrics differed in their ability to statistically explain variations in species richness, with concentrations of soluble reactive phosphorus and chlorophyll a being the most powerful predictors. However, the form of the productivity–richness relationship differed in each case, being linear in the former analysis and quadratic in the latter. Comparison of analyses based on species data from different time periods, revealed that the magnitude of the productivity effect was greatest for long-term species richness and smallest for the richness determined on a single sampling occasion. The proportion of the total species pool that was present on any one sampling date was itself dependent on productivity. Differences in the definition of both productivity and species richness can cause variability in the form of the relationship between the two. This may then confound comparisons between studies that use different methodologies.

Recovery of Crustacean Zooplankton Communities from Acidification in Killarney Park, Ontario, 1971–2000: pH 6 As a Recovery Goal

Despite reductions in atmospheric SO4(2-) deposition and resultant decreases in surface water acidity, widespread biological recovery from acidification has not yet been documented. Temporal trends in crustacean zooplankton species richness (number of species) and composition were examined between 1971-2000 in 46 Killarney Park lakes, Ontario, Canada, to assess the degree of biological recovery in lakes with significant water quality improvements, i.e. pH now > 6, compared to 2 other groups: i) lakes which never acidified; and ii) lakes which are still acidified (pH < 6). Time trends in species richness could not be distinguished among the 3 groups of lakes, nor did changes in species richness indicate recovery. In contrast, the zooplankton community composition of lakes in which the pH increased to above 6, as measured by a multivariate index of species abundances, changed from a "damaged" state to one typical of neutral lakes. Some recovery in composition was also documented for the acidic lakes. While still acidic, the pH levels of these lakes have risen. The extent and pace of recovery in Killarney Provincial Park bodes well for the future of other acidified regions in North America and Europe.

An introduced invertebrate predator (Bythotrephes) reduces zooplankton species richness

Rarely do ecologists have the data needed to assess the impacts of invading species on biodiversity, i.e. pre‐ and post‐invasion census information from both invaded and control sites. Using a 21‐year time series, we demonstrate that the invasion of Harp Lake, Ontario, Canada, by the Eurasian spiny water flea, Bythotrephes longimanus, a zooplanktivore, was accompanied by a rapid and long‐lasting reduction in the average species richness of crustacean zooplankton, particularly of cladoceran taxa. No such reduction was observed in seven nearby un‐invaded lakes over the same two decades. If the Harp Lake results are typical, we predict a widespread reduction in crustacean zooplankton richness on the Canadian Shield for three reasons. Shield lakes provide the invader with good habitat. Its dispersal rates and colonization success are high. Zooplankton richness in Harp Lake is now unusually low for a Shield Lake of its size and acidity.

Crustacean zooplankton species richness: single- and multiple-year estimates

Richness estimates are dependent on the spatial and temporal extent of the sampling programme and the method used to predict richness. We assessed crustacean zooplankton richness in eight Canadian Shield lakes at different temporal and spatial scales using three methods of estimation: cumulative, asymptotic, and Chao's index. Percent species detected increased with the number of spatial, intraannual, or interannual samples taken. Single samples detected 50% of the annual species pool and 33% of the total estimated species pool. This suggests that previous estimates of zooplankton richness, based on single samples in individual lakes, are too low. Our richness estimates for individual lakes approach the total number of zooplankton found in some regions of Canada, suggesting that each lake has most taxa at some time, the majority being very rare. Single-year richness estimates provided poor predictions of multiple-year richness. The relationship between richness and environmental variables was dependent on the method of estimation and the number of samples used. We conclude that richness should be treated as an "index" rather than an absolute and sampling efforts should be standardized. We recommend an asymptotic approach to estimate zooplankton richness because the number of samples taken influenced it less.

Crustacean zooplankton species richness: single- and multiple-year estimates

Crustacean zooplankton species richness: single- and multiple-year estimates

Crustacean zooplankton species richness and associations in reservoirs and ponds of Aguascalientes State, Mexico

We report the species of crustacean zooplankton found in 19 resevoirs and ponds that were sampled at on at least two occasions in Aguascalientes State, Mexico, at a latitude of about 21°30′ North Latitude. We collected a total of 33 cladoceran taxa, 15 calanoid and cyclopoid copepods, an Ergasilus copepod, 2 anostracans, one notostracan species and an amphipod. All these taxa had previously been reported in Mexico. As in more temperate areas, there was a significant correlation between the species richness and lake size. The species-area relationship for Aguascalientes was indistinguishable from that of more northerly lakes. The two most common associations of zooplankton species were (1) those small species that occurred with fish: Daphnia parvula, Diaphanosoma birgei, Leptodiaptomus siciloides, Mastigodiaptomus albuquerquensis, and Thermocyclops inversus, and (2) the large Daphnia schodleri that occurred with the predator Notonecta, in the absence of fish. With minor variations, these two associations also occur throughout temperate North America.

Zooplankton Communities and Water Chemistry of Sudbury Area Lakes: Changes Related to pH Recovery

Temporal trends in pH, alkalinity, and crustacean zooplankton species richness and community composition were studied in 80 Sudbury area lakes sampled in 1971–76, 1981, and 1988–90. Alkalinity and pH have increased in recent years, but many of the study lakes remain quite acidic (modal pH 4.5–4.9). Species richness has also increased, on average, by 1.9 species/lake but is still low in many acid lakes relative to that in circumneutral lakes. Community composition differed among lakes of pH &lt;5.0, 5.0–5.9, and ≥6.0, with some overlap between these groups because zooplankton recovery has lagged behind chemical recovery. Trajectories of community change in recovering acid lakes varied substantially in the early stages of recovery from highly acidic (pH &lt;5.0) to moderately acidic pH (5.0–5.9). In contrast, trajectories in lakes recovered to pH ≥6.0 converged toward the community structure more typical of circumneutral lakes in the 1970's. This suggests that given sufficient time, zooplankton community structure of recovering lakes may approach that of circumneutral lakes.

Recovery of Crustacean Zooplankton Species Richness in Sudbury Area Lakes following Water Quality Improvements

Temporal patterns in the species richness of crustacean zooplankton communities were assessed in eight Sudbury area lakes based on data collected between 1973 and 1986. Excluding a consistently nonacidic reference lake, the study lakes showed general reductions in acidity and trace metal concentrations during this period, related to reduced contaminant emissions from the Sudbury smelters. Despite water quality improvements, several of the study lakes continue to have low pH and elevated trace metal concentrations which have inhibited recovery of zooplankton species richness. However, in lakes with more favourable current pH and lower trace metal concentrations, substantial increases in the average species richness of crustacean plankton communities have occurred, apparently due to both invasion of new species and more frequent occurrence of existing species. These results clearly demonstrate that reductions in acid-forming emissions lead to both chemical and biological improvements in some aquatic systems.

Species richness of crustacean zooplankton in European lakes of different sizes

Species richness of crustacean zooplankton in European lakes of different sizes