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Southern Ocean zooplankton provide globally significant ecosystem services through their role in carbon sequestration, nutrient cycling and food webs. However, the remote and extreme nature of the Southern Ocean creates significant logistical difficulties for studying zooplankton all year round. Here, for the first time in the Southern Ocean, we present the seasonal occurrence of the zooplankton assemblage in the Northeast Scotia Sea using a sediment trap deployed throughout 2018 (P3 observation site, 52.80˚ S, 40.14˚ W). Results show that copepods and pteropods dominated trap abundance, representing 25.0–68.3% and 13.4–72.5% respectively, followed by amphipods (1.0–7.2%) and hydrozoa (0.2–15.6%). The dominant signal in copepods was consistent with previous observations using traditional (net) sampling methods while the relative contribution of pteropods, amphipods and hydrozoa was increased in our trap. Further, zooplankton showed taxon-specific seasonal signals, with a relatively high number of individuals throughout winter, including an increase in hydrozoa occurrences. This observation highlights the importance of zooplankton as source of nutrition for the benthic community in the winter. Our data reiterate the utility of sediment traps for observing zooplankton in remote locations and sampling specific taxa that might be otherwise understudied. [ABSTRACT FROM AUTHOR]

Pollution by active ingredients is one of the most significant and widespread forms of pollution on Earth. Medicines can have a negative impact on ecosystems, and contamination can have unpredictable consequences. An urgent and unexplored task is to study the Lake Baikal ecosystem and its organisms for the presence of trace concentrations of active pharmaceutical ingredients. Our study aimed to conduct a qualitative analysis of active pharmaceutical ingredients, and quantitative analysis of ibuprofen in endemic amphipods of Lake Baikal, using methods of high-performance liquid chromatography and mass spectrometry (HPLC-MS). Acetylsalicylic acid (aspirin), ibuprofen, acetaminophen, azithromycin, dimetridazole, metronidazole, amikacin, spiramycin, and some tetracycline antibiotics were detected in the studied littoral amphipods. We also detected different annual loads of active pharmaceutical ingredients on amphipods. Using the multiple reaction monitoring (MRM) mode mentioned in GOST International Technical Standards, we detected molecules, fragmented as amikacin, chlortetracycline, doxycycline, oxytetracycline, dimetridazole, metronidazole and spiramycin. Thus, we first revealed that invertebrates of Lake Baikal can uptake pharmaceutical contaminants in the environment. [ABSTRACT FROM AUTHOR]

The present work aims to evaluate the macroinvertebrate community associated with macroalgae in earthen pond systems to better understand their potential in detritus recycling and as an accessory production. Sampling took place on the settling pond of an aquaculture research station, where macroalgae permanently occurred at high densities. The results suggest differentiation between seasons but not between sites within the settling pond. Seasonal variation was observable in terms of macroinvertebrate density, biomass, and diversity. Two non-indigenous species of invertebrates were found, the crustaceans Grandidierella japonica and Paracerceis sculpta Amphipods were the most abundant group, and their high nutritional value can be exploited. Detritus and the epiphyte layer are the main food items for the invertebrates, reinforcing the advantages of these organisms being present to enhance the recycling of excess detritus and to transfer organic matter to upper trophic levels. These species, naturally present in aquaculture facilities, can improve the water quality and increase the variability of food nutrients for reared species. [ABSTRACT FROM AUTHOR]

The trophic relationships between bats (Chiroptera) and Lake Baikal biota have been assessed based on microscopic studies of Myotis petax feces (n = 22). From 82 to 86% of samples had fragments of exoskeletons of caddis flies (Trichoptera) and dipterans (Diptera). These taxa include mainly aquatic and semiaquatic species. Many species from these taxa are endemic to Lake Baikal. Terrestrial insects are found in studied samples less frequently (Hymenoptera 41%, Neuroptera 27%, and Heteroptera 9%). Morphological analysis has revealed fragments of Baikal amphipods in two fecal samples of M. pretax. Further molecular studies will make it possible to detect greater invertebrate taxa diversity in fecal samples of bats feeding near Lake Baikal. [ABSTRACT FROM AUTHOR]

Benthic amphipod feeding groups are a well-established trophic classification that is mostly based on field observations and laboratory tests and are used in ecological studies to monitor the ecological state of benthic ecosystems. Globally, carbon and nitrogen stable isotope ratio investigations have provided confirmation of, and novel insights into, the trophic ecology of benthic animals, such as polychaetes. However, stable isotopic examinations of benthic amphipods have been limited. Here, we used microgram samples to compare the species-specific dietary sources, trophic positions, and isotopic niche overlap of selected benthic amphipods from the Gulf of Kachchh, Marine National Park, using elemental analyser-isotopic ratio mass spectrometry (EA-IRMS) of carbon and nitrogen. Overall, all primary carbon sources presented wide variation in the isotopic values of δ13C (6.3‰) and δ15N (greater than 13‰). Conversely, the amphipod taxa displayed relatively narrow range for δ13C (3.9‰) and wider range for δ15N (more than 10‰). The results of the Bayesian mixing model revealed that the benthic amphipods had species-specific feeding preferences. However, the predominant carbon source was organic matter in sediment which reinforced benthic pathways for energy flow for most species. According to the estimated trophic level values (1.62–3.39), these species play a significant role as primary and secondary consumers serving as crucial trophic intermediaries in the food chain, connecting the base to the top consumers. High overlapping ecological niche amongst species was detected by SIBER analysis which indicated co-existence of the benthic amphipods in their respective microhabitats. This signifies wider utilisation of resources and inter-specific feeding preferences with minimal competition amongst amphipod species. [ABSTRACT FROM AUTHOR]

AbstractThis study presents the complete mitochondrial genome sequence of Gammarus nipponensis, a freshwater crustacean found in the western regions of Honshu, Shikoku and Kyushu in Japan. The entire genome is 16,429 bp in length, encoding a standard set of 13 protein-coding genes, two ribosomal RNA genes and 22 transfer RNA genes, as well as the putative control regions. The mitochondrial genome of G. nipponensis is characterized by a high concentration of A and T nucleotides (67.1%). Notably, the mitogenome contains long TATTTTA repeats in the control region 2 at 686 bp long. This newly available genome information will be useful for studying the evolutionary relationships within the genus Gammarus and for understanding diversification among G. nipponensis populations.

The long-term dynamics of production of the glacial relict amphipod Monoporeia affinis was examined in a small subarctic lake. The aims of this study were: (1) to compare the production of amphipods with their biomass; (2) to relate the changes in amphipod population with environmental variables. I hypothesized secondary production could provide better insight into M. affinis population dynamics, than abundance and biomass alone. Production (increment-summation method) and its standard error were estimated based on benthic samples taken at a sublittoral site from June 2002 to May 2019 (as a rule, 4–5 times a year). Production and biomass were highly correlated with each other. The annual P/B ratio varied twofold. However, the majority of estimates did not differ significantly from the mean P/B value for the study period. Effects of environmental variables (water temperature and chlorophyll-a concentration) were pronounced for offspring and juvenile amphipods only. The older amphipods showed no significant correlation with any environmental variables. Despite the initial prediction, no reliable evidence was found that production revealed greater insight into population dynamics of M. affinis. This long-term study confirms that benthic production is mainly a function of biomass. [ABSTRACT FROM AUTHOR]

This study is based on synchronous data collection in the intertidal zone of the raft culture area on Shengsi Gouqi Island from February to July 2022 （the rapid growth period of large seaweed from March to April, the mature period in May, and the decline period from June to July）. Relative importance index, Shannon-Weaver diversity, and Margalef richness index were used in combination with multivariate statistical methods such as clustering and sorting to analyze the species composition, abundance density changes, and clustering characteristics of amphipods attached to different structures on rafts and large seaweed. A total of 24 amphipod species were collected, belonging to 16 genera in 7 families within 2 suborders. Among these, 24 amphipod species were collected in the aquaculture habitat, while only 4 species were collected in the intertidal zone. The dominant species on the aquaculture rafts were Ampithoe valida, Sunampithoe plumosa, Hyale schmidti, Caprella kroyeri, Caprella decipiens, and Caprella equilibra. In the intertidal zone, no dominant species were observed, and the IRI values for all species were less than 5. The overall abundance density of amphipods showed a monthly increasing trend, rising from （580±90）ind./m2 during the rapid growth period of large seaweed from February to April to （3 800±400）ind./m2 during the decline period from June and July. The highest average abundance density among different sites was found on the floaters, with （9 700±400）ind./m2 while the lowest was observed on the mussel strings with （4 800±100） ind./m2. Amphipods had the highest abundance and diversity during the rapid growth period of large seaweed, followed by the mature period, and the lowest values were observed during the decline period. Yibei strings had the highest abundance and diversity indices. In terms of clustering characteristics, amphipod communities not only exhibited significant temporal variations but also significant differences among different sites （P<0. 01）. In terms of amphipods' selection and utilization of different large seaweeds, six amphipod species, including Ampithoe valida, exhibited a significant positive correlation with the biomass of brown and green algae （P< 0. 01）. The study found that large-scale raft-based aquaculture areas support a diverse, structurally varied, and highly abundant amphipod resource. This conclusion can provide an important basis for the construction of artificial habitats in marine ranching and the optimization of ecosystem structure. [ABSTRACT FROM AUTHOR]

This study presents the complete mitochondrial genome sequence of Gammarus nipponensis, a freshwater crustacean found in the western regions of Honshu, Shikoku and Kyushu in Japan. The entire genome is 16,429 bp in length, encoding a standard set of 13 protein-coding genes, two ribosomal RNA genes and 22 transfer RNA genes, as well as the putative control regions. The mitochondrial genome of G. nipponensis is characterized by a high concentration of A and T nucleotides (67.1%). Notably, the mitogenome contains long TATTTTA repeats in the control region 2 at 686 bp long. This newly available genome information will be useful for studying the evolutionary relationships within the genus Gammarus and for understanding diversification among G. nipponensis populations. [ABSTRACT FROM AUTHOR]

Alkylphenols, which are industrial chemicals, are xenoestrogens; however, their sublethal effects on aquatic animals are poorly studied. The aim of this work is to study possible metabolic and reproductive disorders in amphipods using the example of Gmelinoides fasciatus from the Gulf of Finland (Baltic Sea) after experimental exposure to 4-tert-octylphenol (4t-OP) from the group of alkylphenols. The mortality of G. fasciatus amphipods in 4t-OP concentration ranges from 0.5 to 1000 μg/L after 96 h and 7 days increases with increasing concentration. At 4t-OP concentrations of 0.5 and 5 μg/L, the mortality of G. fasciatus has not been observed. At a concentration of 20 μg/L, after 7 days, the mortality of crustaceans is 20%; at a concentration of 100 μg/L, it is 60%. Exposure to sublethal concentrations of 4t-OP (0.5 μg/L) resulted in a decrease in sexual activity of these amphipods after 1 week: only 25% of amphipods retain precopulatory pairs versus 100% in control. Under chronic exposure (28 days) to the lowest concentration, males show signs of demasculinization (a decrease in the width of the gnatopods and an increase in the depth of the coxal plates); females show a decrease in the overall fecundity and irreversible disturbances in the state of embryos (a high proportion (>50%) of embryos stop their development at different stages of organogenesis). The study shows significant functional disorders of metabolic processes and reproduction in crustaceans even when exposed to nonlethal concentrations of octylphenol. These results confirm the high toxicity of this industrial pollutant, the presence of which in the aquatic environment can lead to irreversible changes in the biota. [ABSTRACT FROM AUTHOR]

Live foods such as phytoplankton and zooplankton are essential food sources in aquaculture. Due to their small size, they are suitable for newly hatched larvae. Artemia and rotifer are commonly used live feeds in aquaculture; each feed has a limited dietary value, which is unsuitable for all cultured species. Whereas, copepod and cladocerans species exhibit favorable characteristics that make them viable candidates as sources of essential nutrients for hatchery operations. Due to their jerking movements, it stimulates the feeding response of fish larvae, and their various sizes make them suitable for any fish and crustacean. Even though Artemia is the best live feed due to its proficient nutritional quality, the cost is very expensive, which is about half of the production cost. A recent study suggests the use of amphipods and mysids as alternative live feeds in aquaculture. High nutritional value is present in amphipods and mysids, especially proteins, lipids, and essential fatty acids that are required by fish larvae during early development. Amphipods and mysids are considered abundant in the aquatic ecosystem and have been used by researchers in water toxicity studies. However, the culture of amphipods and mysids has been poorly studied. There is only a small-scale culture under laboratory conditions for scientific research that has been performed. Thus, further research is required to find a way to improve the mass culture of amphipods and mysids that can benefit the aquaculture industry. This review article is intended to provide the available information on amphipods and mysids, including reproductive biology, culture method, nutritional value, feed enhancement, and the importance of them as potential live feed in aquaculture. This article is useful as a guideline for researchers, hatchery operators, and farmers. [ABSTRACT FROM AUTHOR]

There is growing concern surrounding the pervasive impacts of microplastic pollution, but despite increasing interest in this area there remains limited understanding of its disruption to biological communities and the ecosystem services they provide. One such service is the breakdown of leaf litter in freshwaters by invertebrate shredders, such as Gammarus spp., that directly and indirectly provides resources for many other species. This study investigates the effect of microplastic exposure on leaf consumption by two Gammarus species in Ireland, the native Gammarus duebeni celticus, and the invasive Gammarus pulex. Individuals were exposed to 40–48 μm polyethylene particles for 24 h at a range of concentrations (20–200,000 MP/L), with the amount of leaf consumption in that time frame recorded. Microplastics did not affect the feeding rate of either species at environmentally relevant concentrations, indicating that ecosystem services currently provided by our study species are sustainable. However, at higher microplastic concentrations the feeding rate of G. d. celticus was significantly reduced, whereas G. pulex remained unaffected, drawing attention to species-specific and native-invader differences in microplastic impacts. The results of our study further contribute to the observed pattern that invasive species, including various amphipod species, often display a higher tolerance to environmental stressors compared to their native counterparts. This research highlights the need for mitigation of ongoing and increasing microplastic pollution that could differentially influence key ecosystem services and functions. [ABSTRACT FROM AUTHOR]

The presence of shoreline microplastics (1–5 mm) and mesoplastics (5–25 mm) in estuarine ecosystems is ubiquitous, but there remains little data on their composition, contamination status and ecological impacts. Chessel Bay Nature Reserve, situated in the internationally protected Itchen Estuary in Southampton, UK, has serious issues with shoreline plastic accumulation. In evaluating potentially adverse ecological impacts, the influence of quantities of shoreline microplastic (mp) and mesoplastic (MeP) material and adsorbed contaminants (PAHs and trace metals) on the biometrics and population dynamics of the burrowing supralittoral amphipod, Orchestia gammarellus, was assessed in this study. mp/MeP concentrations were variable in surface (0–42%: 0–422,640 mg/kg dry sediment) and subsurface horizons (0.001–10%: 11—97,797 mg/kg dry sediment). Secondary microplastics accounted for 77% of the total microplastic load (dominated by fragments and foams), but also comprised 23% nurdles/pellets (primary microplastics). Sorption mechanisms between contaminants and natural sediments were proposed to be the main contributor to the retention of PAHs and trace metal contaminants and less so, by mp/MeP. O. gammarellus populations showed a positive correlation with microplastic concentrations (Spearman correlation, R = 0.665, p = 0.036). Some reported toxicological thresholds were exceeded in sediments, but no impacts related to chemical contaminant concentrations were demonstrated. This study highlights a protected site with the severe plastic contamination, and the difficulty in demonstrating in situ ecotoxicological impacts. [ABSTRACT FROM AUTHOR]

Endemic amphipods (Crustacea: Amphipoda) of Lake Baikal represent an outstanding example of large species flocks occupying a wide range of ecological niches and originating from a handful of ancestor species. Their development took place at a restricted territory and is thus open for comprehensive research. Such examples provide unique opportunities for studying behavioral, anatomic, or physiological adaptations in multiple combinations of environmental conditions and thus attract considerable attention. The existing taxonomies of this group list over 350 species and subspecies, which, according to the molecular phylogenetic studies of marker genes, full transcriptomes and mitochondrial genomes, originated from at least two introductions into the lake. The studies of allozymes and marker genes have revealed a significant cryptic diversity in Baikal amphipods, as well as a large variance in genetic diversity within some morphological species. Crossing experiments conducted so far for two morphological species suggest that the differences in the mitochondrial marker (cytochrome c oxidase subunit I gene) can potentially be applied for making predictions about reproductive isolation. For about one­tenth of the Baikal amphipod species, nuclear genome sizes and chromosome numbers are known. While genome sizes vary within one order of magnitude, the karyotypes are relatively stable (2n = 52 for most species studied). Moreover, analysis of the diversity of repeated sequences in nuclear genomes showed significant between­species differences. Studies of mitochondrial genomes revealed some unusual features, such as variation in length and gene order, as well as duplications of tRNA genes, some of which also underwent remolding (change in anticodon specificity due to point mutations). The next important steps should be (i) the assembly of whole genomes for different species of Baikal amphipods, which is at the moment hampered by complicated genome structures with high repeat content, and (ii) updating species taxonomy taking into account all the data.

Macrohectopus branickii (Dybowsky, 1874) is the world's only freshwater pelagic amphipod native to Lake Baikal. The habitat of this amphipod is limited to the pelagic zone of Lake Baikal (with periodic nocturnal migrations to the littoral part of the lake). Until now, this amphipod had never been recorded in the rivers flowing into Lake Baikal or in the Angara River flowing out of it. However, on 16 May 2022, near the Taltsy Museum, 20 km from the source of the Angara River, a massive accumulation of Macrohectopus individuals was washed ashore. The reasons for this phenomenon are still unknown. Considering the uniqueness of M. branickii within the world amphipod fauna and its importance for the Lake Baikal ecosystem, the determination of the factors contributing to this phenomenon is of great importance. In this paper we have presented some hypotheses that could explain the appearance of Macrohectopus on the shores of the Angara River. The first hypothesis is that the amphipods could not cope with the current at the source of the river and were carried down the river, and since they are negatively affected by natural light (at the beginning of the morning), they became trapped and died. The second hypothesis is that the Macrohectopus were attracted and disoriented by the artificial light emanating from the nearby villages, before being carried by the current. The third hypothesis relates to the time frame in which this event was observed. This peculiar phenomenon was observed in mid-May, following the melting of the ice on Lake Baikal. Accordingly, Macrohectopus could have been feeding on the lower surface of the ice, or alternatively they could have been frozen in the ice as the ice floes were transported downstream. Each of the hypotheses we have presented does not necessarily exclude the others, but on the contrary may complement them. In this paper we do not exclude the possibility that there are other explanations for this phenomenon. However, if massive washing ashore of Macrohectopus occurs regularly, further research is needed, taking into account, among other things, the influence of washed ashore individuals on the food spectrum of aquatic organisms and waterfowl of the Angara River.

Pollution by active ingredients is one of the most significant and widespread forms of pollution on Earth. Medicines can have a negative impact on ecosystems, and contamination can have unpredictable consequences. An urgent and unexplored task is to study the Lake Baikal ecosystem and its organisms for the presence of trace concentrations of active pharmaceutical ingredients. Our study aimed to conduct a qualitative analysis of active pharmaceutical ingredients, and quantitative analysis of ibuprofen in endemic amphipods of Lake Baikal, using methods of high-performance liquid chromatography and mass spectrometry (HPLC-MS). Acetylsalicylic acid (aspirin), ibuprofen, acetaminophen, azithromycin, dimetridazole, metronidazole, amikacin, spiramycin, and some tetracycline antibiotics were detected in the studied littoral amphipods. We also detected different annual loads of active pharmaceutical ingredients on amphipods. Using the multiple reaction monitoring (MRM) mode mentioned in GOST International Technical Standards, we detected molecules, fragmented as amikacin, chlortetracycline, doxycycline, oxytetracycline, dimetridazole, metronidazole and spiramycin. Thus, we first revealed that invertebrates of Lake Baikal can uptake pharmaceutical contaminants in the environment.

The present work aims to evaluate the macroinvertebrate community associated with macroalgae in earthen pond systems to better understand their potential in detritus recycling and as an accessory production. Sampling took place on the settling pond of an aquaculture research station, where macroalgae permanently occurred at high densities. The results suggest differentiation between seasons but not between sites within the settling pond. Seasonal variation was observable in terms of macroinvertebrate density, biomass, and diversity. Two non-indigenous species of invertebrates were found, the crustaceans Grandidierella japonica and Paracerceis sculpta Amphipods were the most abundant group, and their high nutritional value can be exploited. Detritus and the epiphyte layer are the main food items for the invertebrates, reinforcing the advantages of these organisms being present to enhance the recycling of excess detritus and to transfer organic matter to upper trophic levels. These species, naturally present in aquaculture facilities, can improve the water quality and increase the variability of food nutrients for reared species.

In this work, we extracted chitosan from marine amphipods associated with aquaculture facilities and tested its use in crop protection. The obtained chitosan was 2.5 ± 0.3% of initial ground amphipod dry weight. The chemical nature of chitosan from amphipod extracts was confirmed via Raman scattering spectroscopy and Fourier transform infrared spectroscopy (FTIR). This chitosan showed an 85.7–84.3% deacetylation degree. Chitosan from biofouling amphipods at 1 mg·mL−1 virtually arrested conidia germination (ca. sixfold reduction from controls) of the banana wilt pathogenic fungus Fusarium oxysporum f. sp cubense Tropical Race 4 (FocTR4). This concentration reduced (ca. twofold) the conidia germination of the biocontrol fungus Pochonia chlamydosporia (Pc123). Chitosan from amphipods at low concentrations (0.01 mg·mL−1) still reduced FocTR4 germination but did not affect Pc123. This is the first time that chitosan is obtained from biofouling amphipods. This new chitosan valorizes aquaculture residues and has potential for biomanaging the diseases of food security crops such as bananas. [ABSTRACT FROM AUTHOR]

Climate change is increasing the frequency of extreme fires. In 2019–2020, extreme fires burned 97 000 km2 of native vegetation in south‐eastern Australia, affecting many areas of rainforest, which has historically burned less frequently. One year post‐fires, we surveyed litter macroinvertebrates in 52 temperate rainforest sites. Sites had experienced increasing levels of fire severity (unburnt, medium severity and high severity). We asked how fire severity affected: (1) litter macroinvertebrate habitats; (2) the abundance of litter macroinvertebrate taxa per unit area; and (3) abundance relative to litter habitat (volumetric density). We also estimated the loss of litter macroinvertebrates across rainforests in the study region. High severity burns supported only a fifth of the litter volume and canopy cover as unburnt sites, lower soil moisture and higher herb cover. Medium burns were intermediate. Macroinvertebrate abundance declined with burn severity: high severity burns supported only 26% of the abundance in unburnt sites; medium severity burns supported 80% of that in unburnt sites. Patterns were similar for all taxa, with millipedes declining most. High severity fires resulted in up to 1.90 million fewer macroinvertebrates per hectare; 0.53 million fewer per hectare of medium burn rainforest. Across the study region, we estimate that 60 billion fewer litter macroinvertebrates persisted in temperate rainforests alone. Volumetric densities of many litter macroinvertebrate taxa in high severity burns were marginally higher than in unburnt sites, suggesting nutrients may be more available post‐fire, or that persisting individuals become concentrated in the leaf litter. For less desiccation‐tolerant groups (e.g., amphipods), density declines with increasing severity may reflect the combined impact of low soil moisture and reduced litter cover. Many taxa persisted following high severity fires, but declines were substantial, and taxa differed in their vulnerability. Longer‐term monitoring is required to understand the recovery trajectory and impacts on ecological function. [ABSTRACT FROM AUTHOR]

Marine mesograzers use macroalgae as food and habitat and may have strong top‐down effects on plants and macroalgae. Sympatric mesograzer species often differ regarding host use and feeding behavior, which may lead to distinct impacts by these consumers on primary producers. The amphipods Hyale niger and Ampithoe marcuzzii are mesograzers abundant that co‐occur in Brazilian waters and, although they use several macroalgae as habitat, it is unknown how much the food value of these hosts explains the host use pattern by the two mesograzers. Herein, we investigated the abundance and feeding behavior of the sympatric amphipods H. niger and A. marcuzzii. For that, their abundance on the macroalgal hosts Sargassum filipendula, Padina gymnospora, and Dichotomaria marginata was evaluated seasonally in a rocky shore at Fortaleza Beach, state of São Paulo, Brazil. Also, multiple‐choice and no‐choice feeding experiments were carried out at laboratory to evaluate the feeding behavior of these mesograzers. The abundance of H. niger was similar among the three macroalgal hosts (except during winter), while A. marcuzzii was more abundant on Dichotomaria and Padina than Sargassum in all seasons. Moreover, H. niger consumed more Padina than Dichotomaria and Sargassum in both feeding experiments. In turn, A. marcuzzii preferred to feed on Padina when it had a choice and consumed the three macroalgal hosts at similar levels in the no‐choice feeding experiment. Overall, H. niger and A. marcuzzii differ from each other regarding their feeding behavior and host use pattern. In particular, the food value of macroalgae seems to partially explain the host use by A. marcuzzi, but not by H. niger. The differences between H. niger and A. marcuzzii may result in varying impacts on primary producers. [ABSTRACT FROM AUTHOR]

The growth and production of glacial relic amphipods Monoporeia affinis in a small subarctic lake were studied based on detailed seasonal observations in 2019–2021. Growth and production were closely related to trophic conditions (chlorophyll a concentration). The maximum values were observed at low water temperatures (~5°C) in early summer, coinciding with the spring maximum of chlorophyll. The summer warming of bottom waters was accompanied by a decrease in the growth rate of amphipods, which is apparently associated with the consumption of most of the primary production in the pelagic zone. It is concluded that current climatic conditions can adversely affect glacial relicts even in cold-water lakes of the subarctic zone. [ABSTRACT FROM AUTHOR]

In an isolating experiment on feeding only on arthropods of terrestrial origin, the potential of their consumption by amphipods from a fishless watercourse has been studied. The data confirm the hypothesis that, on the basis of experiments on feeding exclusively on arthropods, it is possible to determine the maximum proportion of their biomass that the selected consumers are able to utilize. The results of such works can be used for a quantitative assessment of the level of possible losses of allochthonous matter and energy for the communities of recipient water bodies due to the feeding activity of consumers from their tributaries. Assessments of this kind may be relevant when making decisions on the food availability for juvenile Salmonids inhabiting recipient water bodies. [ABSTRACT FROM AUTHOR]

The Angara River is one of the largest rivers in Siberia, overregulated by large reservoirs. Reservoir operation entails a change in the habitat for the river biota, as a result of which organisms with high environmental adaptability and resistance to pollution take the leading positions. Only if there is a detailed knowledge of the Angara aquatic life in modern conditions, it will be possible to carry out scheduled activities for the reconstruction of aquatic fauna and fisheries in connection with hydraulic engineering. Nowadays, there is a significant gap in hydrobiological studies of the unregulated lower section of the Angara. The work objective is to identify changes in the bottom fauna of the lower Angara section after the regulation of the Boguchanskaya HPP. In 2015, Boguchanskaya HPP reached the design production level. Samples of zoobenthos were collected in 2015 and 2022. Benthic fauna was studied in the lower reaches of the Angara River at a site of 436 km below the Boguchanskaya HPP dam on both river banks at depths up to 1,5 m. The collection and office analysis of the material were carried out according to generally accepted methodological recommendations. Zoobenthos biotopes are represented by pebble-sandy soil with varying degrees of siltation and macrophytes. The benthic fauna was gammarid-chironomid in nature. In 2022, compared with 2015, an increase in species composition was revealed due to chironomids; on the contrary, the number of species of mayflies and caddis flies decreased. The structural organization of communities changed: there was an increase in the proportion of chironomids and a decrease in the proportion of mayflies, caddis flies and mollusks. The number of chironomids increased by 4 times, and amphipods doubled. The number of caddis flies decreased by about 5 times, mollusks – by 3 times, and mayflies – by 12 times. At the same time, the total number of benthic fauna increased slightly – only by 1.5 times. Currently, the number of benthic fauna is 2,9 thous ind/m2, biomass is 14,6 g/m2. The general trend of the revealed changes is aimed at increasing the number of tolerant bentonts (chironomids and amphipods) and reducing indicator taxa sensitive to pollution (mayflies, stoneflies, caddis flies and mollusks). The reason for the transformation of bottom communities is the cascade regulation of the river. The Boguchanskiy reservoir, which closes the cascade, is the recipient of gradually accumulating changes and has a direct impact on the hydrochemical and hydrobiological regime below the Angara riverbed.

Live foods such as phytoplankton and zooplankton are essential food sources in aquaculture. Due to their small size, they are suitable for newly hatched larvae. Artemia and rotifer are commonly used live feeds in aquaculture; each feed has a limited dietary value, which is unsuitable for all cultured species. Whereas, copepod and cladocerans species exhibit favorable characteristics that make them viable candidates as sources of essential nutrients for hatchery operations. Due to their jerking movements, it stimulates the feeding response of fish larvae, and their various sizes make them suitable for any fish and crustacean. Even though Artemia is the best live feed due to its proficient nutritional quality, the cost is very expensive, which is about half of the production cost. A recent study suggests the use of amphipods and mysids as alternative live feeds in aquaculture. High nutritional value is present in amphipods and mysids, especially proteins, lipids, and essential fatty acids that are required by fish larvae during early development. Amphipods and mysids are considered abundant in the aquatic ecosystem and have been used by researchers in water toxicity studies. However, the culture of amphipods and mysids has been poorly studied. There is only a small-scale culture under laboratory conditions for scientific research that has been performed. Thus, further research is required to find a way to improve the mass culture of amphipods and mysids that can benefit the aquaculture industry. This review article is intended to provide the available information on amphipods and mysids, including reproductive biology, culture method, nutritional value, feed enhancement, and the importance of them as potential live feed in aquaculture. This article is useful as a guideline for researchers, hatchery operators, and farmers.

DNA repeat composition of low coverage (0.1–0.5) genomic libraries of four amphipods species endemic to Lake Baikal (East Siberia) and four endemic gastropod species of the fam. Baicaliidae have been compared to each other. In order to do so, a neighbor joining tree was inferred for each quartet of species (amphipods and mollusks) based on the ratio of repeat classes shared in each pair of species. The topology of this tree was compared to the phylogenies inferred for the same species from the concatenated protein-coding mitochondrial nucleotide sequences. In all species analyzed, the fraction of DNA repeats involved circa half of the genome. In relatively more ancient amphipods (most recent common ancestor, MRCA, existed approximately sixty millions years ago), the most abundant were species-specific repeats, while in much younger Baicaliidae (MRCA equal to ca. three millions years) most of the DNA repeats were shared among all four species. If the presence/absence of a repeat is regarded as a separate independent trait, and the ratio of shared to total numbers of repeats in a species pair is used as the measure of distance, the topology of the NJ tree is the same as the quartet phylogeny inferred for the mitogenomes protein coding nucleotide sequences. Meanwhile, in each group of species, a substantial number of repeats were detected pointing to the possibility of non-neutral evolution or a horizontal transfer between species occupying the same biotope. These repeats were shared by non-sister groups while being absent in the sister genomes. On the other hand, in such cases some traits of ecological significance were also shared.

The question of the possibility of using meiobenthos to monitor the state of bottom sediments in the Baltic Sea, where bottom macrofauna are unstable due to hypoxia, is of interest. The parameters of meiobenthos and the physicochemical characteristics of bottom sediments and bottom water were studied, and the toxicity of bottom sediments was determined by the survival of the amphipod Gmelinoides fasciatus in 10-day tests for 11 stations in the brackish part of the Gulf of Finland (depths of 10–52 m). Principal component analysis revealed two factors explaining 67% of the variability of the variables and groups of stations similar in terms of conditions. Factor 1 combined nine related variables (depth, metal concentrations, sand fraction in bottom sediments, ratio of nematodes and copepods (N/C index), and survival of amphipods), and Factor 2 combined four variables (organic matter and polyaromatic hydrocarbons in BS, phosphates in water and the number of meiobenthos). Thus, bioindication of the environment by meiobenthos is promising, but requires an integrated approach to be applied in monitoring. [ABSTRACT FROM AUTHOR]

Various implantable optical sensors are an emerging tool in animal physiology and medicine that may provide real-time information about body fluids without tissue extraction. Such sensors are often fluorescence-based and require strong visible external illumination during signal acquisition, which causes anxiety or even stress for small animals and thus may influence the physiological parameters being measured. In order to overcome this obstacle, here, we combined a fluorescent molecular pH probe with upconverting particles within a hydrogel fiber suitable for injection into small crustaceans. The green luminescence of the particles under non-visible infrared illumination excited fluorescence of the molecular probe and allowed for pH measurements after correction of the probe readout for luminescence intensity. The developed optical setup based on a common microscope ensured effective visualization of the sensor and spectral pH measurements through the translucent exoskeleton of the amphipod (Amphipoda, Crustacea) Eulimnogammarus verrucosus, endemic to ancient Lake Baikal. Testing the sensors in these cold-loving crustaceans under environmentally relevant temperature increases showed alkalization of amphipod internal media by 0.2 soon after the start of the experiment, while further increases led to acidification by 0.5. The applied approach for simple sensor preparation can be useful in building other implantable optical sensors for light-sensitive organisms. [ABSTRACT FROM AUTHOR]

In recent years, the impact of rising water temperatures associated with global warming on cold-water freshwater organisms has become a major issue, and understanding the physiological and ecological elements that support temperature limits is essential for the conservation biology of freshwater organisms. We describe a new species of thermophilic hyalellid amphipod, Hyalella yashmara sp. nov. from the Peruvian hot spring Baños del Inca Cajamarca and this could potentially contribute to understanding the high temperature preference of these. We found that this new species can live in water temperatures ranging from 19.8 to 52.1°C, that, to our knowledge, is the highest recorded habitat temperature of amphipods. Hyalella yashmara sp. nov. is most similar to H. meinerti Stebbing, 1899 from Peru. However, this new species differs from the latter in features of gnathopods 1 and 2, sternal gills, uropod 3 and telson. A detailed morphological comparison between Hyalella yashmara sp. nov. and Peruvian species is also provided. Our molecular phylogenetic analyses based on the nuclear 28S rRNA and mitochondrial cytochrome c oxidase subunit I (COI) gene sequences strongly support the monophyly of Hyalellidae (= Hyalella). Since Hyalellidae was found to form a sister group with Chiltoniidae, these two families were expected to have originated from a common ancestor that invaded freshwater habitats from marine environments when the continents of South America, Africa and Australia were united as Gondwana. Our findings suggest that the South American species of Hyalella are not monophyletic and that the North American species are likely to share a most recent common ancestor with H. yashmara sp. nov. ZooBank: urn:lsid:zoobank.org:act:190CFB16-7BE4-4786-A97F-0AFD8CD72DEA We describe a new species of thermophilic hyalellid amphipod Hyalella yashmara sp. nov. from the Peruvian hot spring Baños del Inca Cajamarca. We found that this new species can live in water temperatures ranging from 19.8 to 52.1°C, that, to our knowledge, is the highest recorded habitat temperature of amphipods. Our findings suggest that the North American species of Hyalella are likely to share a most recent common ancestor with H. yashmara sp. nov. [ABSTRACT FROM AUTHOR]

The species composition and distribution of crustaceans in the nearshore zone of Valaam Island (Ladoga Lake) have been investigated by a syringe sampler, a dredge, and video recording. Five species of crustaceans, Asellus aquaticus (Linnaeus, 1758), Monoporeia affinis (Lindström, 1855), Pallaseopsis quadrispinosa (G.O. Sars, 1867), Mysis relicta Lovén, 1862 and Gmelinoides fasciatus (Stebbing, 1899); have been recorded at a depth of 1–25 m. The vertical distribution of naturalized Baikal amphipods G. fasciatus is described and features of their coexistence with native species are characterized. The distribution of the alien species depends significantly on wave intensity, types of sediments, and depth range. The distribution of the most numerous native species, P. quadrispinosa, is influenced by the depth range. The types of sediments do not affect the quantity of all native crustaceans in the nearshore zone. The local species successfully compete with G. fasciatus in all conditions. All these species inhabiting the littoral zone are more resistant to wave action when compared with alien species. Therefore, the open littoral zones serve as natural refugees that preserve the diversity of indigenous species. The data on the spatial distribution of crustaceans make it possible to characterize the benthic communities in the poorly studied parts of the littoral and sublittoral zones and, as a result, the food base of bentophagous fishes. [ABSTRACT FROM AUTHOR]

Modern nano-engineered pesticides have great promise for agriculture due to their extended, low dose release profiles that are intended to increase effectiveness but reduce environmental harm. Whether nanopesticides, including copper (Cu) formulations, cause reduced levels of toxicity to non-target aquatic organisms is unclear but important to assess. Predicting how aquatic species respond to incidental exposure to Cu-based nanopesticides is challenging because of the expected very low concentrations in the environment, and the two forms of exposure that may occur, namely to Cu ions and Cu nanoparticles. We conducted Cu speciation, tissue uptake, and 7-day toxicity laboratory experiments to test how a model estuarine organism, the amphipod Leptocheirus plumulosus, responded to two popular Cu-based nanopesticides, CuPRO and Kocide, and conventional CuCl2. Exposure concentrations ranged from 0 to 2.5 ppm, which were similar to those found in estuarine water located downstream of agricultural fields. Cu dissolution rates were much slower for the nanopesticides than the ionic formula, and Cu body burden in amphipods increased approximately linearly with the nominal exposure concentration. Amphipod survival declined in a normal dose-response manner with no difference among Cu formulations. Growth and movement rates after 7 days revealed no difference among exposure levels when analyzed with conventional statistical methods. By contrast, analysis of respiration rates, inferred from biomass measurements, with a bioenergetic toxicodynamic model indicated potential for population-level effects of exposure to very low-levels of the two nanopesticides, as well as the control contaminant CuCl2. Our results indicate that toxicity assessment of environmental trace pollutant concentrations may go undetected with traditional ecotoxicological tests. We present a process integrating toxicity test results and toxicodynamic modeling that can improve our capacity to detect and predict environmental impacts of very low levels of nanomaterials released into the environment.

Microplastics can be ingested by tiny detritivores such as amphipods, with potential consequences on the food chain. The present study characterizes the abundance, chemical composition, and size of microplastics in amphipods found in the Japan Sea coastal environment, which is a hotspot for microplastic accumulation. High amounts of microplastic ingestion and a large discrepancy by amphipod species, Talorchestia nipponensis, Ampithoe valida, and Trinorchestia trinitatis, were observed (between 0.2 and 76.3 particles/individual) which may be due to differences in habitat preference and background contamination. This result indicates that coastal amphipods in particular may ingest large amounts of microplastics. The average microplastic particle size in amphipods was 59 ± 8.6 µm, with 83% of particles smaller than 90 µm, and polyethylene was dominant. This study provides insights into microplastic abundance in coastal amphipods and the context for further studies on coastal amphipod microplastic ingestion. [ABSTRACT FROM AUTHOR]

Protists (eukaryotic microorganisms) commonly form symbiotic associations with crustacean zooplankton, but their diversity, prevalence and ecological roles are underestimated due to the limited scope of previous investigations. Using metabarcoding of the V4 region of the 18S rRNA gene, we characterized the eukaryotic microbiomes of the dominant crustacean zooplankton, specifically copepods, euphausiids, amphipods and ostracods, from the Strait of Georgia, Canada. Sequence reads from the alveolates dominated all zooplankton examined, which mostly comprised ciliates and dinoflagellates of known symbiont lineages. These lineages included not only those of parasitoids but also those of uncharacterized species. Apostome ciliate reads were the most abundant in all hosts except for cyclopoid copepods, which were dominated by the parasitic Syndiniales. Most symbiont lineages showed some degree of host preference, particularly Pseudocolliniidae ciliate parasites with ostracods, but were often detected in all hosts indicating broad host specificity. Reads from free-living protists, including diatoms and surprisingly hydrozoans, were inferred to be part of their diet. Hydrozoans may have been ingested from free organic matter, such as detritus or marine snow, suggesting a likely underestimated pathway of carbon cycling. This investigation contributes to resolving the interactions between zooplankton and protists and the potential ecological significance of symbioses on zooplankton productivity. [ABSTRACT FROM AUTHOR]

The widespread occurrence of microplastics (MPs) has resulted in their interaction with biological processes. Thus, there is a great concern about the potential toxicity of MPs on animal and plant cells and on the possibility that MPs reach humans through the food web. In order to shed light on both issues, laboratory assays were performed for evaluating the effects of polyethylene (PE) microparticles on the aquatic plant Spirodela polyrhiza (L.) Schleid. and the gammarid Echinogammarus veneris (Heller, 1865). Moreover, a stock of MP-treated Spirodela plants was used to feed gammarid individuals, and the presence of MP particles in their digestive tracts was analyzed. Results evidenced the lack of toxic effects of MPs on plants, evaluated at growth and physiological level by biometric parameters, pigment content, and photosynthetic performance estimated by chlorophyll fluorescence imaging through the ETPT (EcoTox Photosystem Tool). Only a slight reduction in pigment-related indices in MP-treated plants was observed. A remarkable genotoxic effect was instead highlighted by Comet assay in the hemocytes of gammarid individuals exposed to MPs, with three times more DNA damage (expressed as Tail Moment) in MP-treated individuals compared to control ones. Finally, the gut content of the gammarids fed with MP-treated plants revealed the presence of 7.6 MP particles/individual, highlighting the occurrence of trophic transfer of MPs among freshwater ecosystem organisms. Novel indications about the potential impact of the PE microparticles in the aquatic compartment are provided. Notably, the transfer of MP particles between primary producer and primary consumer organisms of the freshwater trophic chain and the genotoxic effects associated with the ingestion of such particles by gammarids are issues of concern for the aquatic ecosystem and the food web leading to the human diet. [ABSTRACT FROM AUTHOR]

It is crucial to understand the effects caused by experimental parameters such as temperature, light, and food type on lab and field-based ecotoxicology experiments, as these variables, and combinations thereof, can affect results. The type of substrate used in exposure experiments, however, is generally assumed to have no effect. This may not always be correct. The metabolic changes in the freshwater crustacean, Austrochiltonia subtenuis exposed to copper, using three common substrates, gauze; toilet paper; and cellulose were investigated. Substrate alone did not affect survival, but each substrate elicited a different metabolic response and adult and juvenile amphipods had different substrate preferences. Several classes of metabolites were shown to change in response to different substrates and toxicant. These included disaccharides, monosaccharides, fatty acids, and tricarboxylic acid cycle intermediates. The results illustrate that metabolomic responses can differ in response to experimental factors that were previously thought not to be significant. In fact, our data indicate that substrate should be viewed as an experimental factor as important to control for as more well-known confounders such as temperature or food, thus challenging the current paradigm. Assuming substrate type has no effect on the experiment could potentially lead to errors in contaminant toxicity assessments. We propose that ideal good practise would be that all experimental factors should be evaluated for their potential influence on metabolomic profiles prior to contaminant response experiments being undertaken. [ABSTRACT FROM AUTHOR]

The complexity of the marine environment and the increasing anthropogenic pressure create a necessity to expand existing monitoring approaches. The main goal of this study was to depict the effects of selected, seasonally varying environmental factors on a battery of biomarkers in the benthic amphipod Monoporeia affinis from the Gulf of Riga (GoR). Seasonal variability in acetylcholinesterase (AChE), catalase (CAT), glutathione reductase (GR), and glutathione S-transferase (GST) activities was investigated at six coastal stations (20–30 m) in August and November in 2020 and 2021. In addition, the biomarkers were measured at seven deep-water stations (>30 m) in November 2021. In general, the results indicated no significant influence of the measured environmental variables on the biomarker activities, except for deep-water stations, where chlorophyll a significantly affected enzymatic activity. The current study indicated that M. affinis has a higher GST, CAT and GR activity in summer compared to autumn in coastal stations, showing seasonal variability of these biomarkers. However, summarizing the biomarker levels recorded at each station and season, the integrated biomarker response (IBR) index showed the most stressed health status of the M. affinis populations in the deep-water stations 135 and 107 and coastal regions in the north-eastern part of the GoR (station 160B). This suggests that the impact on enzymatic responses of benthic organisms could be due to port activities leading to the accumulation of pollutants in muddy sediments regionally. Moreover, for the monitoring of biological effects of contaminants there is a need to establish the background levels of biomarkers, i.e., responses to the different natural environmental factors in the GoR region. [ABSTRACT FROM AUTHOR]

In this work, we extracted chitosan from marine amphipods associated with aquaculture facilities and tested its use in crop protection. The obtained chitosan was 2.5 ± 0.3% of initial ground amphipod dry weight. The chemical nature of chitosan from amphipod extracts was confirmed via Raman scattering spectroscopy and Fourier transform infrared spectroscopy (FTIR). This chitosan showed an 85.7–84.3% deacetylation degree. Chitosan from biofouling amphipods at 1 mg·mL−1 virtually arrested conidia germination (ca. sixfold reduction from controls) of the banana wilt pathogenic fungus Fusarium oxysporum f. sp cubense Tropical Race 4 (FocTR4). This concentration reduced (ca. twofold) the conidia germination of the biocontrol fungus Pochonia chlamydosporia (Pc123). Chitosan from amphipods at low concentrations (0.01 mg·mL−1) still reduced FocTR4 germination but did not affect Pc123. This is the first time that chitosan is obtained from biofouling amphipods. This new chitosan valorizes aquaculture residues and has potential for biomanaging the diseases of food security crops such as bananas.

Information on the relationship between the exposure concentrations of metals and their biodistribution among organs remained scarce in invertebrates. The objective of this study was to investigate the effects of Cd concentration on the organotropism, toxico-kinetic and fate of this metal in different organs of gammarids exposed to dissolved radioisotope 109Cd. Gammarids male were exposed for 7 days to three environmental Cd concentrations (i.e. 4, 52 and 350 ng.L−1) before being placed in depuration conditions (i.e. uncontaminated water). At several sampling times, Cd concentrations were determined by 109Cd γ-counting in water, caeca, cephalon, gills, intestine and remaining tissues. Bioconcentration Factors (BCF) and Cd relative proportions in organs were calculated to assess the exposure concentration effect on the bioaccumulation capacities. The dependance of the organ-specific kinetic parameters to Cd water concentrations were estimated by fitting nested one-compartment toxico-kinetic (TK) models to both the accumulation and depuration data, by Bayesian inference. Then, for each Cd concentrations, the metal exchanges among organs over time were formalized by a multi-compartments TK model fitted to all organ data simultaneously. Our results highlighted that, at the end of the exposure phase, BCF and Cd relative proportions, in each organ, were not significantly modulated by water concentrations. Kinetically, Cd accumulation rates in all organs (except intestines) were depended on the exposure concentration, but not the elimination rates. The in vivo management of Cd (i.e. metal exchanges among organs) remained qualitatively unchanged according to exposure concentration. All these results also highlighted key role of that organs in the management of Cd: bioconcentration by caeca, storage by gills and main entry pathway by intestine. This study shows the interest of implementing TK approaches to test the effect of environmental factors on bioaccumulation, inter-organ exchanges and fate of contaminants in invertebrate body to enhance the understanding of the toxicity risk.

Aim: Groundwater harbours an exceptional fauna and provides invaluable ecosystem services, yet is among the least explored and consequently least protected ecosystems. Successful protection of its biodiversity depends on complete species inventories, knowledge of species spatial distribution, and quantification of biodiversity patterns, as well as disentanglement of the processes that shaped biodiversity patterns. We studied the hyper‐speciose amphipod genus Niphargus as a model system within a global subterranean biodiversity hotspot. We linked the biodiversity patterns with possible underlying processes and discuss the needs to include information on different origins of biodiversity into conservation approaches. Location: Europe, Western Balkans. Methods: We analysed biodiversity patterns of Niphargus using two biodiversity metrics, species richness and phylogenetic diversity, on a grid‐based approach. To account for high cryptic diversity, we replaced nominal species with taxonomic units identified in unilocus delimitations (MOTUs). We built a time‐calibrated multilocus phylogeny of 512 Niphargus MOTUs from within and outside the study area, and calculated Faith's phylogenetic diversity, standardized effect sizes of phylogenetic diversity, and residual of phylogenetic diversity regressed onto species richness. Results: Within the study area, we recognized 245 MOTUs, belonging to different Niphargus clades. Species richness is highest in a north‐western hotspot, although some species‐rich cells were detected also in the south‐east. High phylogenetic diversity coincides with high species richness in the north‐west, while in the south‐east it is lower than expected. Main conclusions: We have shown that species richness does not predictably correlate with phylogenetic diversity. This difference suggests that different processes have led to the formation of species‐rich areas in the Western Balkans: through a combination of dispersal and speciation in the north‐west, and local radiation in the south‐east, respectively. This calls for caution in conservation strategies relying solely on number of species and may change the view on conservation priorities within this region. [ABSTRACT FROM AUTHOR]

Changes in the abundance, biomass, and species composition of cyanobacteria, as well as the composition and amount of produced toxins were studied in three types of model communities: at low (1 mg/L) and high biomass (12 mg/L) of planktonic crustaceans and in the presence of nektobenthic amphipods Gammarus pulex (1.4 mg/L) at low zooplankton biomass. Experimentally, more intensive development of cyanobacteria, an increase in their share in phytoplankton, and longer bloom were observed at high biomass of crustaceans. In microcosms with a high abundance of planktonic cladocerans (Daphnia longispina) and copepods (Eudiaptomus), the highest amount of microcystins in water was noted (including up to 536 ng/L of the most toxic form, microcystin LR). The influence of crustaceans on cyanobacteria was associated with their active excretion of biogenic substances (first of all, phosphates). [ABSTRACT FROM AUTHOR]

Per and polyfluoroalkyl substances (PFAS) are of concern to environmental regulators due to their widespread occurrence, persistence and reported toxicity. However, little data exist on the effects of PFAS at environmentally relevant concentrations. The development of molecular markers for PFAS exposure would therefore be useful to better understand the environmental risks of these compounds. In this study, we assessed if such markers could be developed using Gas Chromatography–Mass Spectrometry-based metabolomics. We exposed the freshwater amphipod Austrochiltonia subtenuis to a range of environmentally relevant concentrations of perfluoro-octane sulfonic acid (PFOS), hexafluoropropylene oxide dimer acid (GenX) and perfluorohexanesulphonic acid (PFHxS) for 7 days at five concentrations. A metabolic response was detected in all concentrations and treatments even though the survival rates only differed significantly at the highest exposure levels. The metabolic response differed between compounds but all three PFAS induced changes in the levels of amino acids, fatty acids, and cholesterol, in line with the literature. PFOS was found to bioaccumulate. Both GenX and PFHxS were eliminated from the amphipods, but PFHxS was eliminated at a slower rate than GenX. This information improves our understanding of the sublethal effects of PFAS as well as their environmental fate and behaviour. [ABSTRACT FROM AUTHOR]

Artificial Light at Night (ALAN) threatens to disrupt most natural habitats and species, including those in coastal settings, where a growing number of studies have identified ALAN impacts. A careful examination of the light properties behind those impacts is important to better understand and manage the effects of this stressor. This study focused on ALAN monochromatic wavelengths and examined which types of light spectra altered the natural activity of two prominent coastal species from the Pacific southeast: the talitroid amphipod Orchestoidea tuberculata and the oniscoid isopod Tylos spinulosus. We compared the natural daylight/night activity of these organisms with the one they exhibit when exposed to five different ALAN wavelengths: lights in the violet, blue, green, amber, and red spectra. Our working hypothesis was that ALAN alters these species' activity at night, but the magnitude of such impact differs depending on light wavelengths. Measurements of activity over 24 h cycles for five consecutive days and in three separate experiments confirmed a natural circadian activity pattern in both species, with strong activity at night (∼90% of probability) and barely any activity during daylight. However, when exposed to ALAN, activity declined significantly in both species under all light wavelengths. Interestingly, amphipods exhibited moderate activity (∼40% of probability) when exposed to red lights at night, whereas isopods shifted some of their activity to daylight hours in two of the experiments when exposed to blue or amber lights, suggesting a possible alteration in this species circadian rhythm. Altogether, our results were consistent with our working hypothesis, and suggest that ALAN reduces night activity, and some wavelengths have differential effects on each species. Differences between amphipods and isopods are likely related to their distinct adaptations to natural low-light habitat conditions, and therefore distinct sensitivity to ALAN. [Display omitted] • Exposure to ALAN reduces the activity of sandy beach amphipods and isopods. • Evidence of a circadian rhythm shift was found in isopods in response to two spectra. • Peracarids' response to ALAN reveals photosensitivity variations between species. • Insight on light wavelengths may guide mitigation against coastal light pollution. [ABSTRACT FROM AUTHOR]

A new species of the genus Cyphocaris Boeck, 1871, is described. The material examined was collected during the “Acoustics along the Brazilian Coast” (Abraços 1) project, by micronektonic trawls at a targeted depth of 525 m, off the Rocas Atoll, Rio Grande do Norte state, Brazil. Cyphocaris boecki sp. nov. can be grouped with the eyed species in the genus but differs from them—except for C. faurei K. H. Barnard, 1916 and C. latirama, Hendrycks & Conlan, 2003—in presenting a dorsally smooth pereonite 1. However, the new species can be distinguished from both by its maxilliped inner plate with two robust apical setae, pereopod 7 basis with weakly produced posterodistal lobe, telson lobes without setae, spines or apical nails, and other characters that are individually discussed among them. The new species can be readily differentiated from C. pedroi Sorrentino, Alves, Johnsson & Senna, 2016, also described from Brazil, by presenting eyes, a rounded lateral cephalic lobe, very elongated antenna 2 almost reaching body length, and pereopod 5 basis, with apically acute spur reaching about two-thirds of the propodus. This is the second record of the genus for Brazilian waters.

The waters adjacent to the northeastern coast of Sakhalin Island, Russia, are an important feeding ground for the endangered western gray whale. Data on the energy available to foraging whales from their prey resources is required for researchers interested in modeling the bioenergetics of whale foraging, but little energy content information is available for the benthic prey communities of gray whales in this region. In this study, we describe the energy density (ED), biomass, and total energy availability (ED × biomass) of benthic prey sampled from two gray whale foraging areas adjacent to Sakhalin Island: the nearshore and offshore feeding areas. ED varied almost seven-fold among benthic taxa, ranging from 1.11 to 7.62 kJ/g wet mass. Although there was considerable variation within most prey groups, amphipods had the highest mean ED of all of groups examined (5.58 ± 1.44 kJ/g wet mass). Small sample sizes precluded us from detecting any seasonal or spatial differences in mean ED within or among taxa; however, mean biomass in the offshore feeding area was, in some cases, an order of magnitude higher than mean estimates in the nearshore feeding area, resulting in higher mean total energy available to foraging gray whales offshore (958–3313 kJ/m2) compared to nearshore (223–495 kJ/m2). While the proportion of total energy accounted for by amphipods was variable, this prey group generally made up a higher proportion of the total energy available in the benthos of the offshore feeding area than in the benthos of the nearshore feeding area. Data presented here will be used to inform bioenergetics modeling of the vital rates of mature females in an effort to improve understanding of population growth limits for western gray whales. [ABSTRACT FROM AUTHOR]

Macrofauna associated with the bamboo coral Isidella elongata was analysed in the Balearic Basin at depths of 697–1308 m. The diversity of associated macrofauna and the specific associations identified depended on different morphological characteristics of colonies, such as height or density of rami. Species associated with Isidella consisted mainly of sessile fauna, such as cnidarians (the actinian Amphianthus dornhii and the solitary coral Desmophyllum dianthus) and cirripeds (Gibossaverruca sp.). The strongest relationship (commensalism) occurred for the Pontogeneiidae amphipod Dautzenbergia megacheir, living attached to colonies of Isidella and represented by all population stages from adult (oostegal) females and males to juveniles. Species-coral relationships between Dautzenbergia and bamboo corals (Isididae) are plausible. Dautzenbergia spp. showed morphological differences between Atlantic (described by Walker 1897 as "eyes wanting") and Mediterranean (with well-developed reddish eyes) specimens. This would suggest diversification of this genus, as has been recently suggested for Pleustidae associated with deep gorgonians. The diversity of the macrofaunal community associated with I. elongata was higher in the most mature (larger colonies with higher density) fields found NW of Mallorca, with higher colonies than in other parts of the Mediterranean. This was the only site where Gibossaverruca sp. (a first Mediterranean faunal record) and D. dianthus were collected. These complex associations between macrofauna and deep-water corals may provide arguments to protect these fragile ecosystems as a source of faunal diversity and diversification. [ABSTRACT FROM AUTHOR]

In recent years, morphological analyses and molecular methods have been increasingly used to describe new species of amphipods. Geometric morphometric methods are recognized as part of an integrated approach in taxonomy and are a cost-effective way to identify species, but its application is rare in Amphipoda. Taxonomically, the shape of gnathopods is important in the family Hyalidae, and species could be identified based on changes in these anatomical parts. Previously, Parhyale darvishi Momtazi & Maghsoudlou, 2016, had been described as a very scattered amphipod on a wide range of northern coasts of the Persian Gulf and the Gulf of Oman. In the present study, a geometric morphometric method based on semilandmarks was used to investigate intraspecific gnathopod's shape changes of P. darvishi population in the Persian Gulf and the Gulf of Oman. Therefore, 180 semilandmarks were selected on the propodus of first and second gnathopods of 100 male and 50 female. Data were analysed using tps package software. The results of UPGMA clustering and relative warp analysis reveal cryptic diversity in P. darvishi and show the main morphometric variations between sexes and populations. The present results, clearly separated Bushehr population samples from other studied populations of P. darvishi with concave posterio-distal margin in propodus of first and second male gnathopods and subquadrate propodus of first female gnathopod. Surveying detailed morphology of Bushehr samples confirmed geometric morphometric results. Therefore, Parhyale bushehri sp. nov. was described and distinguished from similar species by revealed propodus shape variations of geometric morphometric analyses and also having setae on the outer ramous of first and second uropods, peduncle of third uropod and some mouthparts characters. Consequently, the results show the integrated approach (numerical variations and statistical analyses along with morphological analyses) in amphipod taxonomy could reveal cryptic diversity. [ABSTRACT FROM AUTHOR]

This study delves into the unexplored distribution and accumulation of chlorinated paraffins (CPs), pervasive industrial contaminants used as flame retardants and plasticizers, within the hadal trenches, some of Earth's most isolated marine ecosystems. Analysis of sediments from the Mussau (MS) and Mariana trench (MT) reveals notably high total CP concentrations (∑SCCPs + ∑MCCPs) of 10,963 and 14,554 ng g -1 dw, respectively, surpassing those in a reference site in the western Pacific abyssal plain (8533 ng g -1 dw). In contrast, the New Britain Trench (NBT) exhibits the lowest concentrations (2213-5880 ng g -1 dw), where CP distribution correlates with clay content, δ 13 C and δ 15 N values, but little with total organic carbon and depth. Additionally, amphipods from these trenches display varying CP levels, with MS amphipods reaching concerning concentrations (8681-16,138 ng g -1 lw), while amphipods in the MT-1 site show the lowest (4414-5010 ng g -1 lw). These bioaccumulation trends appear to be primarily influenced by feeding behaviors (δ 13 C) and trophic levels (δ 15 N). Utilizing biota-sediment accumulation factor values and principal component analysis, we discern that CPs in sediment may come from surface-derived particulate organic matters, while those in amphipods may come from the above carrion. Our findings elucidate the profound impacts of the emerging pollutants on the Earth's least explored marine ecosystems.