Hydrobiologia

Martens, Koen

doi: 10.1007/s10750-023-05402-4pmid: N/A

De Meester, Luc; Declerck, Steven A. J.; Ger, Kemal Ali

doi: 10.1007/s10750-023-05217-3pmid: N/A

Zooplankton plays a pivotal role in lentic water bodies, linking planktonic primary producers to higher trophic levels and being a cornerstone of the planktonic food web of ponds and lakes. Because of its ease of culture, large size, rich ecology, abundance in northern temperate lakes where limnology is rooted, and the ability to work with clones, Daphnia has, in the last centuries grown to become a key model system in ecology, evolution, and ecotoxicology. Consequently, a vast majority of freshwater zooplankton ecology focuses on the role of Daphnia. While generating essential insights, this has also deviated attention from the broad ecological impact of other zooplankton. Here, we emphasize how other zooplankton taxa have an important impact in nature - often in qualitatively different ways than Daphnia. We illustrate this point by focusing on two key zooplankton functions (herbivory and stoichiometry) and suggest research to capitalize on the success story of mechanistic ecological, eco-evolutionary, and genomic Daphnia work to develop a richer set of model organisms. We currently have the tools to do so and integrating mechanistic insights in multispecies settings would foster a better understanding of the rich diversity and ecology of freshwater zooplankton.

Kordbacheh, Azar; Rahimian, Hassan; Fontaneto, Diego

doi: 10.1007/s10750-022-05131-0pmid: N/A

The advent of molecular techniques has resulted in the discovery of previously unknown cryptic species in many organisms, including rotifers, allowing researchers to perform detailed tests on reproductive barriers between closely related taxa. Here, we review the available literature about molecular techniques implemented for detecting cryptic diversity in rotifers and delimiting species, and discuss the potential mechanisms of reproductive isolation among rotifer cryptic species. Half of the evaluated studies used quantitative statistical approaches for species delimitation. Species boundaries defined by molecular approaches were also examined by conducting mating experiments. Those mating experiments were used to test various reproductive barriers. Most (75%) studies that identified reproductive isolation mechanisms provided evidence of prezygotic barriers. The available literatures suggest that behavioral reproductive isolation may have a more important role than other prezygotic barriers in facilitating reproductive isolation. Postzygotic barriers such as hybrid unviability or sterility and female mortality also contribute to reproductive isolation among rotifer cryptic species. The prevalence of prezygotic barriers in our assessment may stem from the difficulty of studying postzygotic barriers, which can require long-term maintaining and monitoring of rotifer populations. Sequencing tools, including whole genome sequencing, could be implemented to investigate the molecular basis of reproductive isolation in rotifers.

Branco, Christina Wyss Castelo; Fintelman-Oliveira, Ewerton; dos Santos Miranda, Viviane Bernardes

doi: 10.1007/s10750-023-05227-1pmid: N/A

In this review we provide an overview of functional traits for freshwater communities, including macrophytes, periphyton, phytoplankton, fish, macroinvertebrates, and more thoroughly testate amoebae, rotifers, cladocerans, and copepods. Our approach provides a synopsis of functional traits of these groups, which is emerging as a valuable tool in evaluating environmental changes and anthropogenic influences. For the zooplankton community gathering information on traits remains a work in progress. Employing a standardized schema when selecting functional traits across zooplankton groups is a non-optional task; this is especially the case for rotifers because to their diversity of forms and feeding strategies. The role of microcrustaceans in trophic chains has highlighted importance of traits for this group, thus providing clues to their ecosystem effects. Here we aim at providing a framework for functional trait selection in aquatic communities prioritizing life strategies in resources acquisition, habitat preference, and life span and reproduction. Notwithstanding, the assembly of a framework of traits remains in progress and with it, is the taking shape of multiple and varying functions and services that the diverse communities are constantly providing within freshwater ecosystems.

Jeppesen, Erik; Davidson, Thomas A.; Meerhoff, Mariana; De Meester, Luc; González-Bergonzoni, Iván; Vidal, Nicolás; Arndt, Hartmut; Jürgens, Klaus; Sommaruga, Ruben; Özkan, Korhan; Lauridsen, Torben L.; Tserenpil, Sh

Rao, Xing; Lu, Jichong; Zhong, Ping; Zhang, Xiufeng; Tang, Yali; Yu, Jinlei; He, Hu; Jeppesen, Erik; Liu, Zhengwen

doi: 10.1007/s10750-023-05277-5pmid: N/A

In temperate shallow lakes, submerged macrophytes facilitate zooplankton development by providing refuge against fish predation and, thereby, indirectly contribute to maintaining a clear-water state through enhanced zooplankton grazing. The role of macrophytes for zooplankton and their grazing potential is less clear for tropical lakes. We investigated crustacean zooplankton in a phytoplankton-dominated basin (algal basin) and two restored basins dominated by macrophytes (macrophyte basins) in the shallow Huizhou West Lake in tropical southern China. We found that copepods prevailed in all basins, but the dominant taxon differed, with omnivorous cyclopoids dominating in the algal basin and herbivorous calanoids in the macrophyte basins. Moreover, the biomass ratios of calanoid:copepod and zooplankton:phytoplankton were higher in the macrophyte basins than in the algal basin. Our results suggest that restoration measures involving macrophyte transplantation and fish removal lead to reduced fish predation on zooplankton, which help to maintain the clear-water state when macrophytes are established due to higher control on phytoplankton. However, unlike in temperate lakes, large-bodied Daphnia were generally absent and the zooplankton:phytoplankton ratio was overall low, indicating a weaker top-down control in tropical lakes, which is likely due to higher fish predation.

Taranu, Zofia E.; Legendre, Pierre; Cusson, Edith; Pinel-Alloul, Bernadette

doi: 10.1007/s10750-023-05259-7pmid: N/A

We studied the community structure of crustacean zooplankton along the biogeographical zones of the St. Lawrence River (Québec, Canada), to evaluate how the riverscale hydrological network formed by water masses, and local-scale aquatic environment, influenced the distribution of crustacean groups (cladocerans, calanoids, cyclopoids and harpacticoids) during the spring (high discharge) and summer (low discharge) hydroperiods. Zooplankton and environmental data were sampled at 52 sites forming 16 transects along the fluvial section zone (FSZ), the fluvial estuary zone (FEZ) and the estuarine transition zone (ETZ) of the St. Lawrence River in May and August 2006. We compared zooplankton community composition among biogeographical zones and fluvial lakes and across the fluvial estuarine continuum. Analyses were carried out using asymmetric eigenvector maps (AEM), redundancy analysis (RDA), and variation partitioning. Spatial distribution patterns revealed a complex river model. Riverscale discontinuities between the fluvial and estuarine transition zones, and the hydrological network of water masses in the fluvial zones, explained better the spatial zooplankton distribution patterns along the fluvial estuarine continuum than the local environment. Spatial variation in the flow network and environmental conditions were the main drivers of zooplankton distributions in spring whereas the flow network of water masses was the most influential factor in summer.

Alekseev, Victor

doi: 10.1007/s10750-023-05198-3pmid: N/A

The distribution of two species Eucyclops (Eucyclops) serrulatus (Fischer, 1851) s. lat. and Eucyclops (Eucyclops) agiloides (Sars G.O., 1909) s. lat. in the water bodies of the Old World is analysed in connection with the theory of continental drift. A hypothesis about the distribution of these morphologically related species and the role of the Tethys Sea in this distribution is presented. In the modern continental fauna of Eurasia, the northern records of E. agiloides s. lat. according to this hypothesis can be attributed to the remains of the fauna of the Paratethys. A similar distribution in South Asia is also shown by local populations of representatives of the genera Mesocyclops, Afrocyclops and Ochridocyclops, which supports the proposed hypothesis of a recent water connection across the continent in the form of Paratethys reservoirs in East Asia. Subspecies Eucyclops agiloides sarsi subsp.n. is described. The identification key for E. agiloides subspecies is provided.

Marrone, Federico; Stoch, Fabio; Turki, Souâd; Naselli-Flores, Luigi

doi: 10.1007/s10750-023-05173-ypmid: N/A

Even in a biodiversity hotspot such as the Mediterranean basin, aspects relating to the distribution of some groups of microcrustaceans still need clarification. In this paper, we critically analyse the available information on diaptomid copepods in Tunisian inland waters and, based on the largest sampling campaign to date carried out in the country, report new data on their distribution. In the frame of this study, 248 crustacean samples were collected from 190 sites, and 10 diaptomid species belonging to 7 genera and 2 subfamilies were found in the samples. Their distribution follows a climate gradient determined by precipitation, and ecological variables mainly affect diaptomid distribution in the study area, while pure spatial factors are of negligible importance. Diaptomid biodiversity is therefore strongly linked to the diversity of inland waters that characterise the country. This is especially true in the wetlands of the Medjerda alluvial plain, where six diaptomid species co-occurred sympatrically, with up to four or five species coexisting syntopically and synchronically in some sites. Unfortunately, the natural water bodies of this plain are currently strongly threatened by urban expansion and agricultural reclamation, and the risk of local extinction for the species they host is increasingly high.

Dawidowicz, Piotr; Barzycka, Karolina; Pijanowska, Joanna

doi: 10.1007/s10750-023-05272-wpmid: N/A

The aim of our work was to experimentally test the hypothesis that changes in the thermal stratification in lakes of the temperate zone, expected as a result of progressive global warming, will cause an increase in fitness costs in a planktonic cladoceran Daphnia, associated with diel vertical migrations. In a programmable thermostatic chamber, Daphnia magna have been cultured from the first juvenile instar till the first reproduction, in thermal regimes corresponding to the conditions experienced by non-migratory (remaining in epilimnion day and night) and migrating (spending nights in epilimnion and days in hypolimnion) animals. We exposed Daphnia to thermal regimes: corresponding to the temperatures typically reigning stratified lakes nowadays (20 °C in epilimnion and 8 °C in hypolimnion), and expected at the end of this century (28 °C and 12 °C, respectively). The analysis of life-history parameters confirmed the assumption of an increase in metabolic costs resulting from vertical migration of Daphnia along with the expected increase in temperature differences between epilimnion and hypolimnion, which is a daily anti-predator refuge for migrating animals. This may consequently lead to significant changes in the composition of lake zooplankton communities, i.e., to an increase in the share of non-migrating species with small body sizes.