Search Results (408)

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

Palynological analysis of seventy-seven cutting samples from six boreholes in the Marañón Basin (northeastern Peru) has identified five distinct Neogene marine incursion events (ME-1 to ME-5), challenging existing models that depict them as short-lived episodes. The diverse palynological assemblages, comprising spores, pollen, freshwater algae, and critical marine indicators—including dinoflagellate cysts, foraminiferal test linings, and copepod eggs—reveal that these incursions were protracted and recurrent, each associated with a maximum flooding surface and bounded by intervals of continental sedimentation. The stratigraphic record shows the earliest event ME-1 (Aquitanian to Late Burdigalian, 23.03–17.7 Ma) identified across all studied wells. ME-2 (latest Burdigalian to Middle Langhian, 17.0–16.1 Ma) is also recorded basin-wide. ME-3 (latest Burdigalian to earliest Langhian 16.5–15.7 Ma) registered in two wells. ME-4 (Late Langhian to latest Serravallian, 14.6–11.62 Ma) registered in only two wells and ME-5 (Early Tortonian, 11.6–10 Ma) is documented exclusively in the southernmost well, culminating in Zanclean (~5.5–3.6 Ma) mangrove development. We interpret the ingress routes for ME-1 to ME-3 to be westward via the Marañón Portal or northward from the Caribbean, associating them with the Proto-Pebas and Pebas systems. In contrast, ME-4 would also be from Amazon trunk or Paraná Portal associated with the Pebas Phase, and ME-5 likely originated from the south through the Paraná Portal, linking it to the Acre Phase. These results demonstrate that Miocene marine incursions into western Amazonia were not brief episodes but represented prolonged periods of marine influence, facilitated by sustained subsidence in the Marañón retro-arc foreland basin. This history reveals a dynamic connectivity throughout the Neogene, with marine conditions acting as persistent biogeographic barriers that critically shaped the region’s Miocene biodiversity patterns. This refined chronology provides a comprehensive regional framework, significantly advancing our understanding of Amazonian paleogeography. Full article

Marine copepods are an essential live feed for the culture of many marine ornamental fish and other finfish species, yet their production is frequently constrained by contamination from free-living ciliates. To address this challenge, the efficacy of three disinfectants (sodium hypochlorite, iodine, and hydrogen peroxide) was evaluated for ciliate removal in cultures of two copepod species, Parvocalanus crassirostris and Oithona colcarva. Appropriate ranges of disinfectant concentrations and exposure durations were identified through a preliminary trial assessing the toxicity to Euplotes spp. over a 5-min period. Subsequent experiments tested three doses of each disinfectant to quantify ciliate removal success and egg hatch rates for each copepod species. Ciliate presence/absence showed no variation (100% in controls, 0% after disinfection), precluding statistical analysis except for one variable iodine trial, which was analyzed using Fisher’s Exact Test. Hatch and recovery rates were analyzed using binomial GLMMs with treatment as a fixed effect and replicate as a random effect, with Tukey-adjusted pairwise comparisons and α = 0.05. Sodium hypochlorite and hydrogen peroxide consistently removed all ciliates across tested concentrations, whereas iodine only achieved complete removal at the highest dose. The effects on hatch rate differed between species, with hydrogen peroxide producing the highest hatch rates in P. crassirostris (approximately 44 to 46% at 50–100 g/L for one minute) and sodium hypochlorite supporting the highest hatch in O. colcarva (up to 92% at 250 mg/L for one minute). These findings demonstrate that disinfectant performance is species-specific and that species-specific disinfection protocols are warranted to improve the reliability of copepod production in marine aquaculture. Full article

This study evaluated the effects of copepod use and copepod conditioning strategies on the growth and survival of long-snouted seahorse (Hippocampus guttulatus) juveniles from 1 to 60 days post-parturition (DPP). Four dietary treatments were tested: Artemia enriched for 24 h with Isochrysis galbana (control), daily collected copepods, copepods unfed for 48 h, and copepods enriched for 24 h with I. galbana. Juveniles fed copepod-based diets exhibited significantly higher growth and survival (p < 0.05) than those fed enriched Artemia. Mean standard length increased from 1.3 ± 0.1 cm at release to 5.9 ± 0.2, 7.5 ± 1.4, 7.1 ± 1.2, and 7.3 ± 1.1 cm at 60 DPP for the enriched Artemia, daily collected copepods, unfed copepods, and enriched copepods treatments, respectively. Wet weight increased from 0.002 ± 0.001 g to 0.44 ± 0.07, 0.81 ± 0.40, 0.68 ± 0.30, and 0.76 ± 0.40 g, while final survival reached 20%, 60%, 33.3%, and 56%, respectively. Compared with enriched Artemia, copepod-based diets markedly enhanced juvenile performance, supporting faster growth and promoting favorable behavioral traits that contributed to improved survival. These results demonstrate that copepods constitute a superior live feed for early juvenile H. guttulatus; however, copepod conditioning strategies directly influence their nutritional quality and, consequently, seahorse growth and survival. The use of copepods throughout the first 60 DPP is therefore not only feasible but strongly recommended for optimizing juvenile H. guttulatus rearing performance. Full article

Copepods are key components of marine food webs, linking primary producers such as microalgae to higher trophic levels, including many fish species. This study investigates long-term changes in the composition, density, and biomass of copepod communities along the Romanian coast of the Black Sea over six decades (1956–2015), based on historical records and recent monitoring from 18 sampling stations. Mean copepod density declined markedly over the study period, particularly during the cold season, decreasing from values exceeding 1000 ind/m³ in the 1960s to <300 ind/m³ after 2000, while biomass showed weaker but comparable long-term fluctuations. Seasonal variability was pronounced, with significantly higher densities and biomass during the warm season. Generalised Additive Models (GAMs) explained up to 40–55% of the variance in copepod density and biomass, depending on the season. During the warm season, phosphate exerted a positive effect on copepod abundance, consistent with bottom-up control via phytoplankton productivity, whereas during the cold season, temperature showed a positive effect and salinity a negative effect, indicating stronger physical control of copepod persistence. Species composition shifted over time, with a reduction in constant species and an increase in rare or accidental taxa in later decades. These results indicate that climate variability and anthropogenic pressures have reshaped copepod communities, with potential consequences for food-web efficiency and ecosystem resilience in the Black Sea. Full article

Mesozooplankton play a pivotal role in marine pelagic food webs, mediating energy and matter transfer between primary producers and higher trophic levels. Daya Bay, a semi-enclosed bay located in the northern South China Sea, has undergone significant environmental changes due to anthropogenic activities, such as thermal discharge from nuclear power plants and eutrophication. This study examined the mesozooplankton community structure, feeding preferences, and food web organization through four seasonal cruises (May 2022, February 2023, August 2023, and November 2023), employing stable isotope analysis and a Bayesian Isotopic Mixing Model. Results indicate that mesozooplankton abundance and diversity were lower in regions affected by thermal discharge, suggesting a suppressive effect of elevated temperatures. Seasonal shifts in dominant species were observed: Penilia avirostris and Dolioletta gegenbauri dominated the community in spring, while Noctiluca scintillans blooms occurred in summer and winter. Isotopic analysis revealed distinct trophic strategies: copepods exhibited omnivorous habits, whereas cladocerans and tunicates showed stronger herbivorous tendencies. N. scintillans functioned as a high-trophic omnivore, preying on copepod larvae and competing for food resources. Overall, the mesozooplankton community was characterized by an omnivory-dominated trophic network, which enhanced resilience yet remains sensitive to anthropogenic disturbances. This study clarifies how human-induced environmental changes reshape trophic pathways in subtropical coastal waters, providing a valuable reference for long-term monitoring and ecosystem management in Daya Bay. Full article

Symbiotic copepods have a wide host group, including not only invertebrates but also vertebrates, with variable symbiotic sites and morphological characteristics. Even though symbiotic copepods exhibit remarkable diversity, our knowledge of them is still very limited, causing significant lacunae in our understanding of their taxonomic characteristics, host associations, and geographical distributions. To fill these knowledge gaps, we have compiled a comprehensive list of symbiotic copepods and their molluscan hosts in the global oceans based on an extensive literature review. The inventory provides a comprehensive synthesis of the diversity, hosts, and geographical distributions of the symbiotic copepods. This review summarizes information on copepods symbiotic with mollusks from 1863 to 2025. Our compilation records a total of 342 symbiotic copepod species associated with more than 435 species of mollusks. This total includes some copepod species for which no specific host has been identified. For each copepod species, we provide details on its hosts, geographical distributions and the original references. Full article

This study examined the digestive and metabolic responses of Naozhou (NZ) stock large yellow croaker (Larimichthys crocea) larvae and juveniles under five developmental feeding stages (DAH3, DAH7, DAH12, DAH19, DAH49) to clarify mechanisms of early nutritional adaptation. Digestive enzyme assays, transcriptome sequencing, and metabolomics were integrated to compare physiological changes across diets. Protease activity increased sharply from DAH7–19 with the introduction of rotifers, Artemia, and copepods, while amylase and lipase activities rose at DAH19–49, reflecting enhanced carbohydrate and lipid utilization during transition to formulated feeds. Transcriptomic analysis showed that differentially expressed genes were enriched in pathways involving protein digestion, lipid and energy metabolism, and cell cycle regulation. The metabolomic analysis further highlighted dynamic changes in amino acid, lipid, carbohydrate, and vitamin metabolism, consistent with transcriptomic findings. The integrated analysis suggests that the coordinated modulation of digestive enzyme activities, gene expression, and metabolite profiles enabled a smooth transition from yolk dependency to live prey feeding and a subsequent use of artificial diets. These findings provide new insights into the early nutritional development of NZ large yellow croaker and provide a scientific basis for the improvement of artificial aquaculture seed production. Full article

This review synthesizes current knowledge on the biology and ecology of the small cyclopoid copepod Oithona similis, a prevalent planktonic species in the Barents Sea, during the period of Arctic warming since the early 2000s. The region serves as an effective model system for examining the influence of different water masses on Arctic zooplankton dynamics. The highest abundances and biomass of Oithona similis are observed in Murmansk Coastal Waters (MCW) and Arctic Waters (ArW). Although its contribution to total zooplankton biomass is generally lower than that of higher copepod taxa, it can account for up to 27–35% seasonally and regionally. Ovigerous females are most abundant in Novaya Zemlya Waters (NZW) and ArW. Egg production rates exhibit a decreasing trend from south to north across the sea. Morphometric analyses reveal an increase in prosome length for both sexes, while relative antenna size diminishes from the south (MCW) to the north (ArW). The highest mortality rates occur during summer, coinciding with peak abundances of Oithona similis, its predators, and parasites, as well as increased interspecific competition. Based on morphological and reproductive parameters, three distinct populations are delineated within the Barents Sea: southern (MCW), central (Atlantic Water/Barents Sea Water), and northern/eastern (ArW/NZW), with respective life cycle durations of 11–12, 9–10, and 11 months, and typically one to two generations per year. The primary environmental drivers influencing population abundance, biomass, size, and reproduction are temperature and salinity, while chlorophyll a concentration predominantly affects mortality rates. Full article

This study investigated variation in mesozooplankton community structure and indicator species in the Yellow Sea and northern East China Sea, based on four surveys conducted at different times of year. Total mesozooplankton abundance ranged from 1063 to 4515 ind. m⁻³, and dry weight ranged from 23.3 to 44.6 mg m⁻³, with higher values observed in May and August compared to October and January. Redundancy analysis explained a modest fraction of the variation in community structure (17.6% in total; Axis 1: 10.5%, Axis 2: 4.6%), with temperature, salinity, and chlorophyll a jointly contributing to the observed gradients. Cluster and indicator species analyses delineated three ecologically distinct regions: (1) a neritic coastal area dominated by coastal copepods and meroplankton; (2) a cold-water region associated with the Yellow Sea Bottom Cold Water (YSBCW); and (3) a warm offshore region influenced by the Jeju and Yellow Sea Warm Currents. Oithona atlantica was consistently linked to the YSBCW, suggesting its potential as a biological indicator of cold-water mass, whereas Clausocalanus minor was confined to warm offshore waters and reflected the seasonal northward expansion of warm currents. These findings demonstrate a clear coupling between mesozooplankton community dynamics and hydrographic conditions during the survey periods. 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

The objectives of this study were to investigate the zooplankton community in the important estuarine areas of Qinhuangdao Sea in the Bohai Sea, analyze the variation characteristics of the zooplankton community, and explore the construction and evolutionary mechanisms of its community structure and function. We conducted zooplankton monitoring in the four seasons of 2024 at Daihe Estuary (DHK), Yanghe Estuary (YHK), Shihe Estuary (SHK), Tanghe Estuary (THK), and Luanhe Estuary (LHK). The results showed that the diversity index and richness index in summer were significantly higher than those in winter (p < 0.05). Based on the body size, feeding habits, reproduction types, life cycles, and escape abilities of zooplankton, the zooplankton in the ecosystem were divided into 17 zooplankton functional groups. The zooplankton examined in this study were divided into 11 functional groups. Except for THK, the dominant functional groups in other estuaries in all seasons were SCF (Small copepods and claocera filter feeders) and LCF (Large copepods and claocera filter feeders); PP (Protozoan photosynthetic autotrophs) and PB (Protozoan bacterivores) functional groups dominated THK. Pearson correlation analysis and RDA multivariate statistical analysis revealed that interspecific competition, PO₄³⁻-P, NO₂⁻-N, and SAL were the primary driving factors influencing community construction. The spatial-temporal variations in T, PO₄³⁻-P, NO₂⁻-N, and SAL in the five estuaries were evident, and the pH and DO in the water environment exhibited a high degree of overlap in seasonal changes. The density of zooplankton functional groups was significantly positively correlated with PO₄³⁻-P, NO₃⁻-N, NO₂⁻-N, NH₄⁺-N and SAL (p < 0.05). Furthermore, the SCF and LCF functional groups played a dominant role. According to the analysis of niche overlap and AC interspecific association, it was shown that zooplankton populations in small-scale areas mostly exhibited negative correlations dominated by competition and predation. In contrast, the functional groups of zooplankton in large-scale areas mostly demonstrated mutually synergistic facilitative relationships. The results of this study showed that interspecific relationships are more important for the community structure of zooplankton. This study contributes to understanding the responses of primary producers and primary consumers to water environmental changes in estuarine ecosystems, laying a foundation for further analyzing the mechanisms of zooplankton community construction and survival strategy selection in special estuarine habitats. It also provides references for the scientific management of estuarine areas and the avoidance of pollution risks. Full article

The majority of research on food webs has focused on temperate lakes, and little is known about the food web of lakes in polar regions. Subarctic lakes are particularly sensitive to climate change, which affects their stability. Therefore, the trophic structure of the food web in such lakes was considered as the object of this study. We studied a clear-water oligotrophic lake located in the subarctic region of Eurasia, specifically in northern Karelia and the White Sea coast of Russia. The study examined both open water periods (summer–autumn) and ice-covered periods (winter–spring) in this lake. Stable isotope analysis of carbon (¹³C/¹²C ratio or δ¹³C value) and nitrogen (¹⁵N/¹⁴N, δ¹⁵N) in producers and consumers was applied and revealed significant seasonal variations in the structure of the food web. The results indicate the presence of both pelagic and littoral/benthic food web compartments, with a notable contribution of autochthonous carbon derived from benthic sources. Omnivorous fish (perch, Perca fluviatilis; vendace, Coregonus albula; nine-spined sticklebacks, Pungitius pungitius) and some benthic invertebrates (mayfly, Ephemera vulgata; bivalves, Sphaerium corneum) had intermediate δ¹³C values, integrating these compartments by obtaining resources from both. Planktonic invertebrates had significantly depleted ¹³C, with the lowest δ¹³C value reaching −41.7‰, indicating an important contribution of methane-derived carbon. The study also revealed close trophic relationships between lake invertebrates and cyanobacteria, namely with planktonic Dolichospermum lemmermannii and benthic Phormidium sp. Seasonal changes in δ¹⁵N values and in trophic position have been observed among predacious omnivorous fish and crustaceans (amphipods, Gammaracanthus loricatus, and copepods, Cyclops scutifer), which are capable of a generalist feeding strategy depending on food availability. Using the example of this lake, it can be concluded that polar lake ecosystems are characterized by different seasonal intakes of allochthonous organic carbon from wetland catchment (humic compounds) and nitrogen because of nitrogen fixation in the air by cyanoprocaryotes. Alternative energy sources, such as carbon derived from methane, can also contribute to the energy balance of lake ecosystems. This study contributes to our understanding of energy flow and connectivity between producers and consumers in high-latitude lakes. Full article

Mesozooplankton are pivotal for Black Sea food webs, yet they are highly vulnerable to hydrographic variability, eutrophication, and human pressures. This study analysed mesozooplankton dynamics along the Romanian coast (2013–2020) across three sectors (north, central, and south) and two distinct periods (cold and warm seasons), integrating Abundance–Biomass Comparison (ABC) curves with Fuzzy Cognitive Mapping (FCM). Results revealed a clear disturbance gradient: the Danube-influenced north supported high abundances of small-bodied taxa; the central sector maintained the most resilient and functionally diverse assemblages; and the southern sector showed chronic degradation with Noctiluca scintillans dominance. ABC curves quantified disturbance, with curve convergence in the north and near overlap in the south during summer, while FCM highlighted network simplification and reduced functional redundancy. Climate scenario simulations projected further declines in cladocerans and meroplankton under warming and freshening, whereas copepods showed relative resilience. Collectively, the findings demonstrate progressive simplification of mesozooplankton and declining energy transfer efficiency, underscoring the need to integrate zooplankton-based indicators into Black Sea monitoring and management frameworks. Full article

The Levantine Basin is the first region of the Mediterranean Sea to be impacted by climate warming and the arrival of non-indigenous species (NIS) via the Suez Canal. Although Levantine zooplankton has been studied previously, recent datasets capable of detecting the occurrence of new taxa, or shifts in community composition, especially in the easternmost part of the basin, are lacking. The present study provides updated information on zooplankton composition from Tyre (South Lebanon). In this study, the occurrence of two copepod families (Canuellidae, Longipediidae) and the first regional record of Facetotecta (Y-nauplii) are reported for the first time in the Levantine Basin. Additionally, although six Calanoida species were recorded as new to the Lebanese fauna, none can be attributed to Lessepsian NIS. Full article