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Two new species of Bryocamptus Chappuis, 1929 from the Russian Arctic from the Bryocamptus minutus species group are described: Bryocamptus putoranus sp. nov. and Bryocamptus abramovae sp. nov. A complete morphological comparison of the new species with the type species Bryocamptus minutus (Claus, 1863) was carried out. Significant interspecific differences were shown at the level of microcharacters, such as integumental sensillae and pores, ornamentation of segments of mouthparts and swimming legs, and pores on swimming legs. A significant correlation has also been shown in the shape of the caudal rami of the females and the antennules of the males, which is likely caused by an evolutionary sexual arms race. Bryocamptus putoranus sp. nov. and B. minutus have a similar structure of caudal rami, but completely different male antennules, which may indicate a convergent origin of modifications and highlights the importance of depicting male antennules in the species descriptions.

Spatial and temporal complexities of reproductive behaviour and sex ratios of two harpacticoid species Canuella perplexa Scott T. & Scott A., 1893 and Bryocamptus sp. were evaluated monthly from September 2007 to August 2008. Collections were made from four ponds at different salinities in the solar saltern of Sfax, Tunisia, considering other environmental features as well. The salinities ranged from 38.0 to 86.1 psu. With rising salinity, the abundance of C. perplexa adults declined from 4550 ± 4160 ind m−3 (pond A1, salinity = 41.5 ± 2.3 psu) to 880 ± 780 ind m−3 (pond C31, salinity = 71.0 ± 4.3 psu). The abundance of Bryocamptus sp. adults increased from 3560 ± 2810 ind m−3 (A1) to 10,080 ± 6890 ind m−3 (C31). The abundance of total adults of C. perplexa was negatively correlated with both salinity (r = − 0.441, n = 18, p < 0.05) and abundance of dinoflagellates (r = − 0.291, n = 18, p < 0.05) and positively correlated with suspended matter (r = 0.389, n = 18, p < 0.05), temperature (r = 0.354, n = 18, p < 0.05), and abundance of diatoms (r = 0.410, n = 18, p < 0.05). The abundance of adults of Bryocamptus sp. displayed only a positive correlation with salinity (r = 0.452, n = 18, p < 0.05). In both species, the sex ratio (males/females) was driven by the variability of female abundance but never exceeded 1.0. For C. perplexa, the egg number per female ranged between 28 and 31; the ovisac length was between 0.39 ± 0.002 and 0.45 ± 0.018 mm. The egg diameter ranged from 0.062 ± 0.001 to 0.065 ± 0.002 mm, and the total length of ovigerous females ranged between 1.2 and 1.35 mm. For Bryocamptus sp., the egg number per female ranged between 19 and 22, the ovisac length between 0.28 ± 0.008 and 0.31 ± 0.003 mm, the egg diameter between 0.041 ± 0.001 and 0.044 ± 0.001 mm, and the total length of ovigerous females between 0.6 and 0.74 mm. The outcome of this study demonstrated that under extreme environmental conditions and increasing salinity the percentage of diatoms and dinoflagellates was found to be an essential factor in controlling the abundance and reproduction traits of both harpacticoids in this study. Furthermore, the sex ratios in these harpacticoid populations are complex as many factors can influence and alter the sex ratios in natural populations.

Lake Baikal (LB) is the only freshwater ancient lake on Earth where animals inhabit all bathymetric zones down to the deepest sites (approximately 1640 m). However, there is very little data on the composition of their abyssal harpacticoid fauna. On the basis of the samples collected in LB in 2010–2017 at a depth of 270–1632 m, analysis of the fauna composition and species diversity of harpacticoids in the deep-water zone is presented. Studies were conducted in all parts of the lake, including areas of a hydrothermal, oil–methane seeps, and mud volcanoes. Nineteen Baikal endemic morphological species of the genera Bryocamptus, Attheyella, and Moraria (Baikalomoraria) were found. A brief description of the taxa morphology is presented. The genus Bryocamptus was the richest by species number at the studied sites, and Bryocamptus smirnovi Borutzky was the most frequent. The most diverse (8 species) was the fauna of the Saint Petersburg methane seep. Studies have shown that the taxonomic diversity of harpacticoid copepods in the deep-water zone of LB is lower than in its littoral zone. According to two non-parametric species estimators (Chao 2 and Jackknife 1), a 1.5-fold increase of species richness of harpacticoids of the LB abyssal is expected.

AbstractThe first description/overview of the freshwater copepod fauna of the order Harpacticoida from the Lena River delta is presented. Various habitats and regions were studied. As a result, we identified 18 species belonging to two families: Canthocamptidae and Harpacticidae. Eight of the identified species are new to the study area; five species belonging to the genera Bryocamptus, Canthocamptus, Moraria, and Maraenobiotus, presumably represent new species for science. We provide brief ecological descriptions of the species identified in the Lena River delta and analyze their differences from the typical populations. The harpacticoid fauna of the Lena delta consists of three main components including Palaearctic species, Holarctic species, and species with “Beringian” distribution patterns. We provide a morphological description of Bryocamptus umiatensis Wilson 1958. This species is quite similar to Bryocamptus jejuensis Lee and Chang 2016, recently described from Korea. The main character distinguishing these species is the ornamentation of the anal operculum. This character in our region reveals considerable interpopulation variations. We also provide an identification key to the freshwater Canthocamptidae of the Lena delta.

Material of a Bryocamptus species, formerly reported as B. umiatensis Wilson, 1958 from Sakhalin and South Korea, is here recognized as a distinct new species. Specimens of both sexes were recently obtained from an alpine wetland, Sumeunmulbaengdui, located in the Hallasan National Park, Korea, and newly registered as a Ramsar Wetland in 2015. The new species, B. jejuensis n. sp., differs from the type population of B. umiatensis from Alaska by the smooth margin of the anal operculum in both sexes, the peculiarly modified terminal seta on the distal endopodal segment of the male leg 3, the sword-like spinous seta on the distal endopodal segment of the male leg 4, and the presence of a setule row on the inner distal margin of the caudal rami in the female. Both sexes of the new species are described in detail with particular reference to the male characters. A revised key to the seven species of the genus Bryocamptus Chappuis, 1929 occurring in Korean waters is provided.

The influence of stream age and environmental variables on meiofaunal assemblages were examined for 15 streams across a temporal gradient of 200 yr in Glacier Bay National Park, southeast Alaska. Meiofaunal assemblages were found in all streams but varied in diversity and abundance. Copepod species found had a wide range of habitat affinities and good dispersal abilities; we argue that the observed copepod assemblage in a given Glacier Bay stream is determined by habitat availability rather than dispersal constraints. Two-way indicator species analysis (TWINSPAN) classified the meiofaunal assemblages largely according to stream age. Stepwise multiple regressions were performed on environmental variables and meiofaunal species richness or abundance, and predictors differed between taxa. The sorting coefficient, a measure of the diversity of particle sizes in the sediment, best explained the variation in both total harpacticoid copepod abundance and meiofaunal taxon richness (together with stream gradient). Harpacticoids were more abundant in relatively well-sorted streams and declined as the range of particle sizes within the streams increased; the opposite pattern to that found in the marine environment. The abundance of Bryocamptus spp. was best explained by models incorporating stream age and indicators of habitat complexity, whereas abundance of Tardigrada, Chaetogaster, and Moraria affinis increased with increasing substrate stability. A habitat templet was developed for the meiofaunal assemblages in Glacier Bay streams. Stream age (incorporating stream habitat complexity) formed one axis and the second axis was the sorting coefficient.

Abstract not available. The general absence of harpacticoid copepods in studies on biodiversity and ecology of the freshwater meiofauna can be ascribed, in part, to the difficulties in properly identifying these small animals. Here, we report the occurrence of nine species of the order Harpacticoida occurring in the Zezere River basin, central Portugal: 1 species of Phyllognathopus, 1 of Parastenocaris, 2 of Elaphoidella, 2 of Attheyella, and 3 of Bryocamptus. Parastenocaris and Phyllognathopus dwell in the psammon habitat and Parastenocaris can also be found in thick biofilms covering hard substrates. All members of the Canthocamptidae recorded, with the exception of Attheyella (Neomrazekiella) trispinosa, lived in both interstitial and epibenthic habitats. A. (N.) trispinosa occurred only when the substrate was covered with filamentous algae, bryophytes, or other macrophytes. In order to facilitate future ecological studies on the Portuguese harpacticoid fauna, we describe the diagnostic morphological characters of the females of the species sampled, and illustrate the morphological characters of females of seven species of those. We make additional reference to morphological characters of males that were common in the samples or showed variability relative to descriptions in the literature. A key to the genera and species, based on female morphology, is supplied for the area surveyed. PortugeseA ausencia generalizada de copepodes harpacticoides nos estudos de biodiversidade e ecologia de meiofauna de aguas continentais pode ser parcialmente atribuida a dificuldades de identicacao correcta destes organismos de pequenas dimensoes. Neste estudo referimos o ocorrencia de nove especies da ordem Harpacticoida colhidas na bacia do Rio Zezere: 1 especie de Phyllognathopus, 1 de Parastenocaris, 2 especies de Elaphoidella, 2 de Attheyella e 3 de Bryocamptus. Parastenocaris e Pyllognathopus sao habitantes do psammon e Parastenocaris foi tambem encontrado em biofilmes espessos que cobrem o substracto rochoso. Exceptuando Attheyella (Neomrazekiella) trispinosa, todos os membros da familia Canthocamptidae habitam os habitats intersticial e epibentonico. A. (N.) trispinosa so foi registada em locais onde o substracto estava coberto por algas filamentosas, briofitos ou outras macrofitas. Com o intuito de facilitar futuros estudos ecologicos da fauna de harpacticoides Portugueses, descrevemos os caracteres morfologicas diagnosticantes das femeas das especies amostradas e ilustramos os caracteres das femeas de sete das especies descritas. Fazemos tambem referencia a caracteres morfologicos de machos abundantes nas amostras ou que apresentam variabilidade relativamente a descricoes publicadas. A chave de identificacao apresentada com base na morfologia de femeas visa permitir uma identificacao rapida dos harpacticoides da area amostrada. Articles that cite this article?

Microbial activity, bacterial and invertebrate densities and particulate organic matter (POM) content were assessed using a modified freeze-coring technique in a Welsh mountain stream. Bacterial cell densities ranged between 0.22 × 10⁸ and 4.47 × 10⁸ cells cm⁻³ and increased with sediment depth reaching maxima in depths between 30 and 40-cm. In contrast, the highest microbial activity (ETS) was found at depths between 5 and 15 cm, sharply declining with depths > 20 cm. POM content was substantially higher in the upper sediment layer (0–5 cm) and declined with increasing sediment depth. Higher nitrogen and organic carbon contents were recorded for particles < 63 µm than for larger size fractions. Meio- and macroinvertebrate densities were signifi cantly and negatively correlated with bacterial number. The results of a multiple regression analysis suggest that bacterial densities, porewater volume and particulate organic carbon (POC) accounted for more than 50 % of the density variations of harpacticoids and larval chironomids. The results underline a strong link between physical habitat properties in a scale-dependent fashion.

The sensitivity of harpacticoid copepods was tested against selected pollutants. Acute toxicity tests were carried out for five hyporheic species exposed to pesticides, ammonia, and metals. The stygoxene Bryocamptus zschokkei, B. minutus, B. pygmaeus and Attheyella crassa; and the stygophilous B. echinatus were sampled and cultured during 8 months in controlled conditions. A first test protocol is presented. The acute endpoints among species fell within one order of magnitude. The sensitivity among various species evaluated in this study is consistent and the choice of species for further sediment/groundwater assessment is not specific to a chemical class. These potential test organisms would be more suitable to protect meiofaunal communities.

Toxicity test protocols for establishing the effect of zinc on the freshwater copepod Bryocamptus zschokkei are reported. In the absence of food, larval life‐history stages were more sensitive than adult females to acute zinc exposure with a 96‐h median lethal concentration of 0.62 mg Zn/L (0.52–0.73 mg Zn/L, 95% confidence intervals) for copepodids. The acute toxicity of zinc to adult females was also significantly reduced in the presence of food (a leaf disc). The main toxic effect of zinc in a life‐cycle test was a reduction in the number of offspring per brood at 0.48 mg Zn/L. As this endpoint corresponded with zinc concentrations causing reduced juvenile survival, prolonged embryonic development times, and mortality during hatching, it appears that zinc had a direct toxic effect on the current brood rather than an indirect effect on egg production via maternal reallocation of resources. The lowest‐observed‐effect concentration for reproduction of measured zinc concentrations of 0.48 mg Zn/L corresponded with environmental concentrations of zinc causing reduced population densities of this copepod in the field. It is proposed that B. zschokkei is an ecologically relevant test species for evaluating the potential effects of contaminants on freshwater invertebrates and for giving insight into the mode of action of a test chemical.