Rotifera in lake subhabitats Ejsmont-Karabin, Jolanta; Karpowicz, Maciej
Aquatic ecology,
12/2021, Letnik:
55, Številka:
4
Journal Article
Recenzirano
Lake ecosystems contain numerous habitats, such as the relatively homogeneous pelagial, as well as many different subhabitats in the littoral zone. Among rotifer communities inhabiting the littoral ...zone are those living in organic sediments (epipelon), on submerged stones (epilithon), among sand grains (hydropsammon), on animals (epizoon), on submerged branches and twigs (epixylon) and on macrophytes (epiphyton). The aim of this work was to explain differences in species richness among rotifer communities inhabiting these subhabitats. Qualitative and quantitative analyses of the structure and diversity of rotifer species were based on studies carried out in the summers of 2009–2020 in lakes in northeastern Poland. The analysis of the structure and density of rotifer species inhabiting different lake subhabitats suggests that although the communities are subject to similar ecological characteristics, there are marked differences in the species richness and diversity of the communities. A characteristic feature is the presence of species sharing subhabitats and species assigned to only one habitat type.
The taxonomic status of the genus Bythotrephes Leydig (Crustacea: Cladocera) has been debated since the second half of the XIX century. The most widespread view of recent decades has been that ...Bythotrephes is a monotypic genus, which was support by preliminary molecular data. However, the recent detailed morphological revision of this genus clearly distinguishes at least seven species. Therefore, we performed a multi-lake survey in Central Europe to give new insight into the taxonomic status of Bythotrephes by combining genetic analysis with traditional morphology-based taxonomy. Based on the morphology we identified two species in Central Europe, B. brevimanus and B. lilljeborgi, as well as hybrid forms. For the genetic analysis, we used newly obtained 113 sequences of mtDNA COI gene of the 535-bp length Bythotrephes from Central Europe and sequences downloaded from GenBank. There were no significant differences between all analyzed sequences, which supports the hypothesis that Bythotrephes is a monotypic genus, with only one highly polymorphic species. On the other hand, the results of our work could point out that the COI gene is insufficient to evaluate the taxonomic status of Bythotrephes. Nonetheless, we have identified 29 new haplotypes of mtDNA COI, and one which was the same as the haplotype found in North America and Finland. Furthermore, this haplotype was the source variant from which most other haplotypes were derived.
The ciliate–metazooplankton trophic coupling is well documented from both laboratory and field experiments. The knowledge about these relationships during winter ice-covered periods is very scarce. ...The abundance and composition of planktonic ciliates, rotifers and crustaceans were studied during the ice-covered and ice-free periods in the Łuczański Canal (Masurian Lakeland, Poland). We hypothesised that in winter, rotifers play a major role in the top-down control of ciliates and that ciliate–metazooplankton relationships differ not only between the ice-covered and ice-free periods, but also between ice-covered months. Our study showed that ciliates formed a significant part of zooplankton biomass during the winter ice-covered period when crustaceans occurred in very low abundances. Despite cold water temperature and the presence of ice cover, time was probably a cue that initiates zooplankton development. The ciliate, rotifer and crustacean numbers and biomass, as well as chlorophyll
a
concentrations, were lower in February than in ice-free periods. In the winter month with ice cover, bottom-up control by resources was more important than top-down control by zooplankton grazing in regulating ciliates. In the spring month with ice cover, crustaceans and rotifers may include ciliates as an important part of their diets. In April, the studied groups of organisms were not related to each other in contrast to the summer, when zooplankton communities were closely related to each other. In autumn, rotifers may play an important role in controlling ciliates. The abundance, composition and ciliate–metazoan relationships can vary considerably not only across seasons, but also across ice-covered months.
The hyporheic (phreatic) zone connects groundwater and surface water and hosts a diverse community of organisms that are adapted to its unique conditions. In order to investigate the hitherto poorly ...understood biotic connections between the hyporheic zone and temporary ponds, we analyzed changes in the community of Copepoda in a small and shallow ephemeral puddle in a meadow for one year, with comparison to the groundwater fauna of the surrounding region in northeastern Poland. In the puddle, three species of Cyclopoida (Acanthocyclops vernalis, Diacyclops bisetosus, and Cyclops furcifer) were present in large numbers throughout the year. These species were also common components of the region’s groundwater fauna, but in much lower densities in the groundwater than in the puddle. These results suggest that temporary puddles can be a convenient place for copepods to feed and reproduce, while groundwater may serve as an important corridor for their dispersal. This study contributes to a more comprehensive understanding of copepod ecology and the functioning of ephemeral aquatic habitats.
This study presents the diversity and structure of pelagic zooplankton in north-eastern Poland. The research was conducted in 47 lakes with different trophic conditions in the middle of summer. ...Samples were collected close to the deepest part of the lakes to avoid the diverse benthic and littoral zones. We found 119 zooplankton species of which 32 were Cladocera, 16 were Cyclopoida, 4 were Calanoida, and 67 were Rotifera. We determined which species occurred most frequently in the region, as well as the species that were characteristic of different trophic conditions. We also recorded the presence of eight cold-adapted species which some of them are considered as glacial relicts (e.g., Eurytemora lacustris, Heterocope appendiculata, Cyclops lacustris). Our research revealed potential glacial refugia for planktonic species in 14 lakes of NE Poland. Our study suggests that the presence of stenotherm species may be an excellent indicator of the ecological status of deep lakes and could be considered in lake monitoring programs. Furthermore, we did not find Bythotrephes longimanus which has been reported from Poland. Instead, we found that B. brevimanus was the most common representative of the genus in the study area.
Humic compounds and related factors are the main constraints for the development of zooplankton in humic lakes, leading to low transfer efficiency in food webs. The results of this study indicated ...that some zooplankton species could have an advantage under these conditions. We found that the mass development of omnivorous Asplanchna priodonta in temperate humic lakes could be caused by the domination of high nutritional algae such as Gonyostomum semen and Botryococcus braunii. These algae are too large for most zooplankton to ingest, but A. priodonta can feed on a wide range of particles and benefit from this high-nutritional food. Small cladocerans (Ceriodaphnia, Bosmina) might be favored when picoplankton and small algae-dominate humic lakes. Therefore, some zooplankton species could have an advantage and control the development of phytoplankton, leading to the effective transfer of matter and energy in the planktonic food web in humic lakes.
Zooplankton community data from 45 dimictic lakes, representing homogenous abiotic conditions, were used to distinguish indicator taxa of near-pristine, reference lakes with low anthropopression. ...Reference conditions were selected based on natural land use in the catchment, lack of or low human activity, and the absence of point sources of pollution, as well as good water quality. According to these criteria, six lakes were designated references and all represent mesotrophic conditions. Reference lakes had a low abundance of Cyclopoida and Rotifera, and significantly lower biomass compared to non-reference lakes. We have found that species characteristic of the reference lake were: Bosmina (Eubosmina) coregoni, Ascomorpha ecaudis, Collotheca pelagica, and Gastropus stylifer. The species responsible for differences among reference and non-reference lakes were Keratella tecta, Pompholyx sulcata, and Ascomorpha saltans, which are considered typical for eutrophic waters.
We evaluated how eutrophication and humification impacted nutrient cycles and the efficiency of carbon transfer in the planktonic food webs of 12 lakes in north-eastern Poland that differed in ...trophic state. Our results indicated that the effectiveness of carbon transfer between phytoplankton and zooplankton varied from 0.0005% to 0.14%, which is much lower than the theoretical 10%. The highest efficiency of carbon transfer occurred in the mesotrophic lakes due to the higher hypolimnetic zooplankton production, while the lowest efficiency was observed in the dystrophic lakes and in one eutrophic lake that was dominated by cyanobacteria. Inedible algae (e.g.
Gonyostomum semen
) and cyanobacteria appeared to be the main factors reducing the efficiency of the transfer of matter in pelagic food webs. The results of our study showed that plankton communities are a key component of the nutrient cycle in freshwater food webs. Phytoplankton were a very effective nitrogen sink, and in the mesotrophic lakes, up to 99% of the total nitrogen was sequestrated in phytoplankton. As a result, there was a depletion of inorganic nitrogen in the upper water layer. Furthermore, zooplankton were an important phosphorus sink, thus significantly influencing the nutrient cycles.
Deep chlorophyll maxima (DCM) are a common phenomenon in low-trophic stratified lakes, and there is much less information about the occurrence of DCM in eutrophic and dystrophic lakes. Therefore, we ...performed
in situ
continuous measurements of chlorophyll concentration by a submersible spectrofluorometer in 23 temperate lakes with different trophic conditions (mesotrophic, eutrophic, and dystrophic). We perform chemical analyses of available nutrient forms to better understand the mechanism of DCM formation. We found the highest concentration of phytoplankton in the metalimnion or upper hypolimnion of most studied lakes, regardless of trophic conditions. Nevertheless, the differences in the number of phytoplankton between DCM and epilimnion were largest in low-trophic lakes, where the chl
a
concentration in DCM was even 15 times higher than that in the epilimnion. The mesotrophic lakes showed vertical niche segregation by phytoplankton, with a general pattern − green algae in the upper layer, below diatoms, then cryptophytes (and cyanobacteria). Our results indicated that the main factor for DCM in mesotrophic and eutrophic lakes was epilimnetic nutrient depletion, while in dystrophic lakes, it seems to be caused by other factors due to the depletion of dissolved nutrients in whole water profiles.
Epibionts often colonize the exoskeleton of crustaceans, which sometimes results in the development of a long-term relationship between them. Our present work confirmed that a specific epibiont is ...closely associated with the pelagic calanoid copepod Eurytemora lacustris, regardless of the region, which suggests a preserved interaction between these species. Molecular analyses revealed that the epibiont belongs to the genus Tokophrya. We also found that the level of basibiont colonization is related to its size and identified that the most intensely inhabited body parts are those located near the center of the copepod body. We hypothesize that the relationship between Eurytemora (basibiont) and Tokophrya (epibiont) was established during the Quaternary period, following which these two populations were fragmented into lakes where they survived in close interaction. In addition, we suppose that the close relationship between the two species indicates the coevolution of stenotherms. Further studies on the interactions between Eurytemora lacustris and Tokophrya are required in order to gain insight into the long-term relationship between the copepods and the epibionts.
PDF
