Confusing Invader: Acanthocyclops americanus (Copepoda: Cyclopoida) and Its Biological, Anthropogenic and Climate-Dependent Mechanisms of Rapid Distribution in Eurasia

Unlocking rivers' hidden diversity and ecological status using DNA metabarcoding in Northwest Spain

Rivers are crucial ecosystems supporting biodiversity and human well-being, yet they face increasing degradation globally. Traditional river biomonitoring methods based on morphological identification of macroinvertebrates present challenges in terms of taxonomic resolution and scalability. This study explores the application of DNA metabarcoding analysis in both bulk and environmental DNA (eDNA) samples for comprehensive assessment of macrozoobenthic biodiversity, detection of invasive and endangered species, and evaluation of river ecological status in northwestern Spain. DNA metabarcoding of homogenized bulk samples and water eDNA revealed a mean of 100 and 87 macrozoobenthos species per sample respectively. However, the specific composition was significantly different with only 27.3% of the total species being shared. It was not possible to identify all the OTUs to species level; only 17.43% and 49.4% of the OTUs generated could be identified to species level in the bulk and eDNA samples, respectively. Additionally, a total of 11 exotic species (two first records for the Iberian Peninsula and another three first records for Asturias region) and one endangered species were detected by molecular tools. Molecular methods showed significant correlations with morphological identification for EQR values (Ecological Quality Ratio) of IBMWP index, yet differences in inferred river ecological status were noted, with bulk samples tending to indicate higher status. Overall, DNA metabarcoding offers a promising approach for river biomonitoring, providing insights into biodiversity, invasive species, and ecological status within a single analysis. Further optimization and intercalibration are required for its implementation in routine biomonitoring programmes, but its scalability and multi-tasking capabilities position it as a valuable tool for integrated monitoring of river ecosystems.

Biodiversity of zooplankton (Rotifera, Cladocera and Copepoda) in the tributaries of Cheboksary Reservoir (Middle Volga, Russia)

Background

Freshwater zooplankton is an important component of the ecological communities of inland water bodies. It acts as an important part of the food web and participates in the self-purification processes of aquatic ecosystems. To study the abundance and distribution of species, a sampling event dataset was compiled and then published through GBIF. The aim of the work was to describe the current zooplankton fauna (Rotifera, Cladocera and Copepoda) and its abundance, based on a recently published dataset. The research was conducted from 2015 to 2022. Zooplankton samples were collected by vertical towing a plankton net (70 μm mesh) from the bottom to the water surface or by filtering through a net, the water being collected with a measuring bucket. The samples were concentrated to 100 ml and fixed with a final concentration of 4% formalin solution. For each sampling event, the coordinates of the location, number of individuals and date were recorded.

New information

The dataset contains information on 259 taxа, including 257 species and subspecies of zooplankton from 36 families found in the tributaries of the Cheboksary Reservoir. The families Chydoridae (35 species), Brachionidae (31) and Cyclopidae (27) were the most species-rich. Four invasive species were found: Kellicottiabostoniensis (Rousselet, 1908), Acanthocyclopsamericanus (Marsh, 1893), Ilyocryptusspinifer Herrick, 1882 and Thermocyclopstaihokuensis Harada, 1931.

Structural Organization of Zooplankton Communities in Different Types of River Mouth Areas

The gradients of hydrological, hydrophysical, and hydrochemical conditions form the transition zones in river mouth areas. These areas are considered ecotones in the presence of the edge effect. Our research aimed to identify the main patterns in the structural organization of zooplankton communities in different types of river mouth areas in lowland reservoir tributaries within the Middle Volga basin. A cluster analysis was performed to structure and determine the zooplankton communities. The identified zooplankton communities were characterized by the noticeable heterogeneity in the species structure. We analyzed the spatial distribution of the structural indicators of zooplankton communities and, on the basis of RDA, determined the factors that significantly affect the organization of the ecotone community. An ecotone was found in all types of river mouth areas where the highest density, biomass, diversity, species, and functional richness of zooplankton were noted, as compared to bordering zooplankton communities. As the morphological structure of the mouth areas became more complex, the values of the main structural parameters of zooplankton communities increased. It was demonstrated that conditions in the ecotones are favorable to the development of zooplankton alien species. The major factors determining the species structure of the ecotone zooplankton community were water electrical conductivity (R2 = 21.07%, p-value = 0.001), dissolved oxygen content (R2 = 10.33%, p-value = 0.003), and water transparency (R2 = 9.77 %, p-value = 0.001).

Ust-Luga Seaport of Russia: Biological Invasions and Resting Stages Accumulation

This article describes the results of a three-year study of invasive species of aquatic ecosystems in the vicinity of Ust-Luga, the largest Russian seaport in the Baltic. Taking into account the great importance of the participation of marine vessels in the dispersal of invasive species, an experimental study of the seasonality of accumulation of resting stages of aquatic invertebrates in the ballast compartments of a vessel located in the Baltic Sea of the Gulf of Finland was carried out. Experiments show that the time of filling the ballast compartments in late summer and autumn poses the greatest risk for the spread of aquatic invertebrates with ship ballast water. In the Baltic Russian port, 11 invasive species of zooplankton and zoobenthos were found, which comprises 15% of the biodiversity in the samples. Copepoda demonstrated the highest presence of invasive species in class among zooplankton groups (14%) and Malacostraca among benthos groups (80%). Alien species findings correspond to the main vectors of invasive species dispersal for the Baltic Sea: North America, Indochina, and the Ponto-Caspian region.

DISTRIBUTION OF SOME PONTO-CASPIAN AND ALIEN COPEPODS (CRUSTACEA, COPEPODA) IN PLANKTON OF THE DON RIVER BASIN

In 2018-2019, the zooplankton was studied in the Don River from the source to the mouth including the Tsimlyansk Reservoir, Volga-Don shipping canal, and the upper part of Taganrog Bay of the Sea of Azov. Habitats of two Ponto-Caspian species of copepods ( Heterocope caspia and Eurytemora caspica ) and of three alien species, Mediterranean copepod Calanipeda aquaedulcis , a representative of the neritic zone Acartia ( Acanthacartia ) tonsa and East Asian euryhaline Thermocyclops taihokuensis were found. For the first time, the findings of T. taihokuensis were recorded in the Don River upstream and downstream of the Tsimlyansk Reservoir and in water bodies of the Volga-Don shipping canal. It is shown that the Ponto-Caspian Eurytemora caspica inhabits the Don River basin and Taganrog Bay of the Sea of Azov. The European copepod E. affinis which was previously recorded in the region was not found in the studied areas of the basin. The occurrence (>80% of samples) of the Ponto-Caspian species and Calanipeda aquaedulcis was the highest. A recent invader Thermocyclops taihokuensis reached the maximum abundance (>100 000 ind./m). By an example of the Tsimlyansk Reservoir, it is found that the way of the spread of the Ponto-Caspian and alien species in the Don River basin may be large-scale activities on the introduction of planktonic and benthic invertebrates conducted in the 1950-1970s in order to improve the food supply of valuable fish species. The history of dispersal of the studied copepod species and their population characteristics are discussed.

The Inland Water Copepod Fauna of a Traditional Rural Landscape in a Mediterranean Island (Crustacea, Copepoda)

Although the Mediterranean area is a well-known hotspot of biological diversity, the crustacean assemblages inhabiting inland waters of the Mediterranean islands are to date unevenly known, and detailed information is missing for most taxa and areas. In the frame of this paper, we provide a checklist and a characterization of the copepod fauna of the lentic water bodies occurring in a traditional rural landscape of Sicily, where the co-existence of agriculture, woodlands, and pastoral activities lead to the presence of a wide range of different aquatic habitats. Overall, 22 copepod species belonging to the orders Calanoida, Cyclopoida, and Harpacticoida have been found in the 92 surveyed sites, stressing the conservation value of the area. In the study area, species widespread in the west Palaearctic region co-exist with strictly Mediterranean elements and a small but biogeographically significant group of species with northern or Balkan affinities, which support the role of the investigated area as a refugium for species that colonised Sicily during Pleistocene climate fluctuations and are now restricted to the more wet parts of the island. A single non-native species has been found, and its distribution is currently limited to permanent, man-made reservoirs.