Search Results (137)

Groundwater ecosystems host unique and functionally important fauna, yet they are increasingly threatened by salinization driven by natural processes and human activities. Despite growing attention to groundwater quality, little is known about how salinity shapes subterranean crustacean assemblages on small carbonate islands. This study examines how groundwater salinity influences the distribution of stygobitic (i.e., highly specialized organisms that complete their whole life cycle in groundwater) and non-stygobitic crustaceans in groundwater habitats of the Pianosa Island (Tuscan Archipelago, Italy). We sampled ten bores, measured key physicochemical parameters, and identified crustaceans collected through on-site filtration. Principal Component Analysis and Canonical Analysis of Principal coordinates highlighted a clear spatial pattern of crustacean assemblages along a salinity gradient: stygobitic species occurred only in low- and intermediate-salinity bores while non-stygobitic taxa dominated sites with elevated electrical conductivity and high Na⁺ and Cl⁻ concentrations. The most saline bore contained no stygobitic species. Insights from this study point to salinity as a key driver of groundwater biodiversity on small Mediterranean islands and highlight the vulnerability of stygobitic fauna to ongoing salinization. Full article

This study, conducted on the Cap-Vert peninsula (Dakar, Senegal), examines the epifaunal communities associated with macroalgae, revealing significant variations depending on the species of algae. In 2023 (in situ samples), amphipods dominated most macroalgae, particularly Coralina officinalis (29.40%) (Rhodophyceae), Chlorophyceae (30.38%), and Codium sp. (29.38%) (Chlorophyceae). In 2022, copepods (76–92%) were most abundant on Sargassum spp. and Ulva spp., which had washed up on the beach. A significant link between epifaunal abundance and macroalgae species highlighted their ecological interdependence. These findings are of relevant interest for West Africa’s blue economy, where the growing exploitation of wild macroalgae could disrupt these ecosystems. Sustainable management must take into account epifaunal species, particularly those found on structurally important macroalgae (e.g., Corallina sp., Codium sp.). The study recommends including macroalgae-epifauna associations in biodiversity inventories, particularly in marine protected areas, and continuing research on influencing factors (e.g., algal morphology, environmental conditions). Mass strandings of Sargassum spp. and Ulva spp. can cause mortality in marine larvae and eggs, leading to a local reduction in recruitment. Future research integrating these conclusions could allow a more detailed analysis of the epifauna on macroalgae. Ecosystem approach is essential to strike a balance between economic development and biodiversity conservation. Full article

In temperate freshwater ecosystems, zooplankton play a crucial role in the pelagic food web and act as sensitive indicators of environmental change. They respond to shifts in water temperature, hydrodynamic mixing, and short-term meteorological events. This study investigated the epilimnetic zooplankton fauna of Lake Karamurat (Bolu, Türkiye), a small tectonic temperate lake, with a specific focus on the influence of rainfall events and wind speed on community structure. The samples were taken seasonally and horizontally using a plankton net (55 µm mesh size) and were analyzed alongside in situ physico-chemical measurements and meteorological data. In total, 74 zooplankton taxa were identified, comprising 54 rotifer species and 20 crustacean species (16 Cladocera and 4 Copepoda). Testudinella greeni was recorded for the first time in Türkiye, representing a new addition to the Turkish Rotifera fauna. Multivariate analyses revealed that electrical conductivity, water temperature, dissolved oxygen, precipitation, and wind speed were key drivers shaping community composition. The findings suggest that wind-driven surface mixing and episodic rainfall events enhanced vertical redistribution, leading to dominance of rotifers and small-bodied cladocerans in the epilimnion. These findings underscore the critical role of sampling strategy in shallow lakes under dynamic conditions and provide new faunistic insights into the zooplankton diversity of Anatolian lakes. Full article

Currently, the synonymy of the two morphologically analogous copepod species, Mongolodiaptomus birulai (Rylov, 1922) and M. formosanus Kiefer, 1937, remains doubtful. While examining the detailed morphology of diaptomid copepods from China, Cambodia, and Vietnam, we came across two undescribed species whose morphology is closely similar to that of M. birulai from Northeast China and M. formosanus from Taiwan. In this paper, descriptions of M. parabirulai sp. nov. from Yunnan, Southwestern China, and M. longiserratus sp. nov. from Cambodia and Vietnam are presented. The first new species, M. parabirulai sp. nov., can be distinguished from its congeners in the male P5 by it having the distal outer portion of the second right exopod produce a wing-shaped expansion and its strongly robust left and right basis. The second new species, M. longiserratus sp. nov., can be differentiated by the following characteristics in the male: the spiniform process on segment 20 of the right antennule is longer than that of segment 21 and has a serrate outer margin, and the right P5 basis has two (longitudinal and semicircular) hyaline lamellae. Furthermore, the status of M. birulai and M. formosanus is reviewed and recommended. Full article

Understanding the mechanisms that maintain biodiversity is crucial for effective conservation in riverine ecosystems. However, the direct and indirect mechanisms by which land use patterns and water quality parameters influence plankton α- and β-diversity remain poorly elucidated. Here, we undertook a comprehensive survey of plankton communities across the Jialing River basin. Our results showed that Bacillariophyta and Chlorophyta were the dominant phytoplankton groups, whereas Protozoa and Copepoda predominated among zooplankton. Redundancy analysis identified dissolved oxygen and total phosphorus as key environmental factors shaping plankton community structure. Additionally, random forest models indicated that anthropogenic stressors exerted consistent effects on both α- and β-diversity of phytoplankton. Importantly, the decomposition of β-diversity revealed that species turnover constituted the major component, underscoring the importance of basin-scale management approaches. Structural equation modeling further demonstrated that land use practices predominantly affected phytoplankton β-diversity indirectly via water quality alterations, with a relatively weak direct effect. In contrast, neither the direct nor indirect effects of land use were significant for zooplankton communities. These findings suggest that phytoplankton may serve as more reliable bioindicators of anthropogenic disturbance than zooplankton in this freshwater system. Moreover, our findings highlight the central role of water quality in regulating phytoplankton diversity responses to environmental change. Consequently, we recommend that conservation strategies in the Jialing River basin focus on water quality monitoring and the mitigation of its ecological effects. Full article

Natural ecosystems, especially those regulated by floods, are sensitive to prolonged temperature fluctuations that affect hydrology and the lateral connection between the river and its floodplain. Here, we analyzed a series of zooplankton data collected monthly from 2007 to 2016 during the ice-free period in Kopački Rit Nature Park in the Middle Danube, an area important as a food source and nursery area for fish stocks in the Danube. The aim was to find out how the long-term change in temperature and fluctuating environmental parameters affect the succession of zooplankton in the warmer (from April to September) and colder parts of the year (from October to March). Throughout the decade, total nitrogen concentrations showed significant differences between years, with an increase since 2012. Despite the increase in nitrogen levels and the expected increase in primary production, the higher nitrogen levels were accompanied by lower zooplankton biomass. A significant difference was found between the values of the zooplankton geometric mean index, with 73% of the variance explained by the difference between groups. In general, a trend toward a significant decrease in zooplankton biomass, with a simultaneous increase in the number of species and high turnover rates, was observed throughout the decade. Full article

A new species of copepod, Anchimolgus jejuicus n. sp., is described based on specimens collected from the external washings of the scleractinian coral Alveopora japonica Eguchi, 1965, off Jeju Island, Korea. The new species closely resembles A. multidentatus Kim, 2003, associated with Alveopora catalai Wells, 1968, from New Caledonia in having similar body lengths and similar shapes of the antennae, mouth organs, and swimming legs. However, the new species can be distinguished from the New Caledonian species by the shorter female caudal ramus, which is 1.70 times longer than wide; by the shorter third endopodal segment of the female antenna, which is 3.35 times longer than wide; by the reduced second spine of the distal lash of the maxilla, which is less than half as long as the first spine; by the relatively shorter inner distal spine of the second endopodal segment of female leg 4, which is 1.56 times longer than the outer spine; by the shorter exopodal segment of female leg 5, which is 3.39 times longer than wide; and by the exopod of male leg 5 armed with one spine and one seta. The present paper reports the northernmost distribution area of the genus Anchimolgus, near the latitude of 33°24′ N off Jeju Island. In addition, the recent rapid increase in populations of the host coral Alveopora japonica around Jeju Island—likely driven by climate change—highlights the significant ecological consequences for both the scleractinian coral and its newly discovered symbiotic copepod. Full article

The role of abiotic factors in the allelopathic interactions between copepods and rotifers is poorly documented. Temperature has a marked effect on the metabolism of zooplankton. Therefore, the release of allelochemicals by copepods and the response of rotifers to them may change as temperatures increase. Here, we tested the effect of two temperatures (20 and 25 °C) on the population growth of Brachionus havanaensis cultured on a conditioned medium (CM) of Arctodiaptomus dorsalis and Eucyclops sp. The CM was obtained daily, separately, for the males and females of both copepod species at a density of 0.1 ind. mL⁻¹ for 24 h prior to experiments. In the controls and CM treatments, higher temperatures had a stimulatory effect on the population growth and the rate of population increase (r) of B. havanaensis. At 25 °C, the CM from the females and males of A. dorsalis caused >30% increase in r, but for the CM from Eucyclops sp., this effect was lower (<21%). At 20 °C, the r in the controls and CM treatments was not significantly different. The morphometry of B. havanaensis varied depending on the treatments. Compared to controls, longer loricae were recorded in the CM of male A. dorsalis at both temperatures. However, in the CM of female calanoids, longer rotifers were observed only at higher temperatures. At 20 °C, the CM from Eucyclops produced smaller loricae. The relationship between the lorica length and width of rotifers showed a linear relation but the slope differed among the treatments. Full article

We highlight the lack of researchers studying freshwater zooplankton in Latin America and contextualize it within the global extinction of taxonomists, global loss of biodiversity, and regional reality to visualize the intensity of this threat and possible strategies for addressing it. The scarcity of researchers working on freshwater zooplankton currently threatens the future of these studies in the world. This global trend of the decreasing interest of scientists and local governments in learning about this important component of freshwater biodiversity is more accentuated in Latin America by regional drivers, such as brain drain, a lack of support by stakeholders, and the absence of planning for the rational use and conservation of this essential natural resource. All these drivers interact and have more dramatic consequences for regional research due to the recent reduction in government funds for science in some of these countries. In the context of Global Change; a loss of biodiversity due to this fact; and the misuse of drainage basins, overexploitation, and regional pressures, the lack of researchers studying freshwater zooplankton and, in general, all aquatic life has emerged as a critical threat to the delicate equilibrium of these ecosystems. Within this situation, scientific integration through intra-regional and extra-regional collaboration networks has emerged as an unavoidable strategy for the survival and future strengthening of studies on biodiversity and the conservation of freshwater zooplankton in Latin America. The development of new technologies such as DNA barcoding, metabarcoding, and metagenomics has emerged as a solution to this problem. Nevertheless, they should be considered as new tools towards integrative taxonomy and not as replacements for taxonomical studies. Full article

This study investigates phytoplankton and zooplankton assemblages and their relationships with environmental factors along trophic gradients in 50 lentic ecosystems across Thailand. Field sampling was conducted at 264 points in April and May 2024. Physical, chemical, and biological parameters were measured both in the field and the laboratory. Plankton samples were identified and quantified to assess species richness, abundance, and community composition. The results revealed that lentic water bodies could be classified into four trophic states: 1 oligotrophic, 6 mesotrophic, 17 eutrophic, and 26 hypereutrophic systems. This study found that phytoplankton density peaked in hypereutrophic waters, while species richness was highest in oligotrophic conditions. Nutrient-rich environments favored Cyanophyta dominance, whereas Dinophyta were more abundant in nutrient-poor systems. Zooplankton assemblages, particularly Rotifers and Copepoda, showed higher abundance in eutrophic and hypereutrophic ecosystems, while diversity was greater in mesotrophic and oligotrophic waters. Statistical analyses indicated that environmental factors, especially nutrient concentrations, played a significant role in shaping plankton assemblages along the trophic gradients. Cyanophyta showed strong positive correlations with total dissolved solid (TDS) (r = 0.383, p < 0.01) and electrical conductivity (EC) (r = 0.403, p < 0.01), while Dinophyta showed a strong positive correlation with dissolved oxygen (r = 0.319, p < 0.05). Zooplankton, particularly Rotifers, exhibited significant correlations with total phosphorus (TP) (r = 0.358, p < 0.05) and TDS (r = 0.387, p < 0.01). Multidimensional Scaling (MDS) analysis and Principal Coordinate Analysis (PCoA) confirmed that water quality variables strongly influenced community structure. This study provides important insights into how environmental factors drive phytoplankton and zooplankton assemblages across trophic gradients in Thai lentic ecosystems, contributing to the improved understanding and management of freshwater bodies and eutrophication. Full article

A new genus of Ectinosomatidae is recorded in association with an Ascidia from a permanent submerged coral community in Barra Beach, Salvador City, Bahia State (Brazil). The new taxon belongs to a smaller group of genera in the family Ectinosomatidae based on the geniculate maxilla and the prehensile first swimming leg. This group is composed of Bradiellopsis, Chaulionyx, Halophytophilus, and Sigmatidium. The new genus differs from the others due to distinct aspects of the mandible gnathobasis, which features sharp processes on the pars incisiva and pars molaris followed by a short spinulated area and a serrulated seta; the presence of a two-segmented endopod of the first swimming leg, with the first endopodal segment longer than all exopodites combined; and a short, quadratic second endopodal segment with two strong curved claws. In addition, it differs from other genera due to the distinct armature of the first to fourth swimming legs and the presence of fused exopod and baseoendopod on the fifth swimming leg. Cruscollatus gen.nov. lives specifically within the digestive tract of Eudistoma vannamei Millar, 1977, an Ascidia species endemic to northeastern Brazil. This study reports the first documented association between a harpacticoid copepod of the family Ectinosomatidae (order Harpacticoida) and ascidian hosts (Ascidia). Full article

Meiofauna are frequently overlooked in biodiversity assessments, resulting in a lack of understanding regarding their current status, the potential impact of anthropogenic activities, and climate change. This study on the intertidal zone of the Small Beach of Ostend marks a new effort to characterize meiofaunal communities along the Belgian coast. Sampling was carried out on five separate occasions throughout the year, with abiotic data collected during each event. Collected specimens were sorted according to their taxonomic group, resulting in a retrieval of 1742 organisms. Among these, Platyhelminthes and Nematoda were most abundant. Through metabarcoding of the 18S ribosomal region, a biodiversity assessment was conducted, yielding a total of 106 Amplicon Sequence Variants (ASVs). After filtering out rare reads, 65 metazoan ASVs were retained: 18 representing Platyhelminthes, 16 Nematoda, 15 Copepoda, 12 Polychaeta, and 4 Acoela. Identification of the ASVs through blasting generated 23 unique species-level identifications. The highest species richness was observed among Proseriata and Nematoda, each comprising six different species. Additionally, four different species of Polychaeta and Copepoda, two species of Acoela, and one species of Rhabdocoela were identified. Compared to findings on similar beaches along the Belgian coast from about 40 years ago, the meiofaunal communities on this beach exhibit an overall low species richness. Finding fewer and other species might be linked to the potential impact of beach nourishments, human trampling, and climate change. However, confirming this hypothesis requires future research. Full article

The patterns of meiofaunal distribution in a submarine canyon and adjacent open-slope habitats at Campos Basin, southwest Atlantic, were investigated. A total of eight stations was sampled, four inside the Canyon Almirante Câmara and four on the adjacent open slope. These stations represented four isobaths (400, 700, 1000, 1300 m) and were sampled during two distinct periods (2008, 2009). At each station, three replicates were obtained and sectioned into layers of 0–2, 2–5 and 5–10 cm. Nematoda was the most abundant group in both habitats, comprising more than 85% of the total meiofauna in both sampling periods. The density and assemblage structure of the meiofauna showed high variability between the 400 m isobath and the other three isobaths in the canyon habitat. These results reinforce the roles of habitat heterogeneity and the availability of food sources as key factors strongly influencing the deep-sea meiofauna in the southwest Atlantic Ocean. Phytopigments were significantly correlated with the two major meiofaunal groups (Nematoda and Copepoda), as well as with total meiofaunal density, only in the canyon habitat. On the adjacent open slope, only copepods showed a significant correlation with sediment characteristics (mean grain size and carbonates), suggesting that distinct environmental factors influence the distribution of meiofauna in the two habitats. Full article

This study presents the first scientific evaluation of food web integrity in the Black Sea under the Marine Strategy Framework Directive (MSFD) Descriptor 4 (Food Webs), utilizing zooplankton indicators to assess the environmental status during the warm season (May to October) from 2018 to 2023. The research aims to analyze trophic interactions, biodiversity patterns, and ecological stability by examining three key indicators: the Shannon–Wiener diversity index, Copepoda biomass, and Mnemiopsis leidyi biomass. The findings reveal that the Shannon–Wiener diversity index failed to achieve Good Environmental Status (GES) in any of the four Marine Reporting Units (MRUs), suggesting insufficient community diversity and potential ecological imbalances. Copepoda biomass met GES criteria only in marine and offshore waters, indicating spatial variability in copepod population stability across the Black Sea. Meanwhile, M. leidyi biomass remained within GES thresholds in all MRUs, suggesting that its population levels do not currently threaten the food web, despite its known invasive impact. This study provides critical baseline data on food web structure and dynamics in the Black Sea, offering a scientifically grounded framework for future ecological monitoring and management strategies. The results emphasize the need for targeted conservation efforts and adaptive management approaches to enhance the ecological health of the Black Sea in alignment with MSFD objectives. Full article

The diversity of the species-rich copepod family Laophontidae T. Scott, 1905, is rarely investigated in China. Based on the recent collections from the coasts of the Yellow Sea in Shandong, two species of the genus Quinquelaophonte Wells, Hicks and Coull, 1982 were first reported from China, with one identified as new. The new species, Quinquelaophonte xinzhengi sp. nov., differs from other congeners by the following characteristics: female caudal ramus about 3.2 times as long as maximum width; P1 enp-2 bearing one claw and one minute seta; female P3 exp-3 with two inner setae, male P3 exp-3 with one inner seta; P4 exp-3 with one inner seta; and female P5 exopod bearing six setae. The COI genetic divergences between the new species and three closely related congeneric species all exceed 20% (21.5–22.3%), supporting their separate species status. Our samples of Q. enormis Kim, Nam and Lee, 2020, which are first found in China, show subtle differences with the original description of the type specimens from Korea on basis of maxilliped and P2 enp-1 with cuticular bulge subapically, female P3 and P4 without conspicuous morphological variation. This is also the first report of Quinquelaophonte from the China Seas. Full article