Search Results (53)

South Korea is one of the world’s major centers for marine shellfish aquaculture. Since the industry’s rapid expansion began in the 1980s, concerns have grown regarding its environmental impacts on coastal marine ecosystems. Evaluating the benthic ecological quality status (EcoQs) of shellfish farms using benthic indices provides a scientific foundation for the sustainable management of aquaculture areas. In our study, five benthic indices (AZTI’s marine biotic index, BENTIX, benthic opportunistic polychaeta amphipoda index, benthic pollution index, and multivariate AMBI) and one composite index were selected to assess EcoQs of shellfish farms in Gangjin Bay, South Korea. Our results revealed significant differences in macrobenthic community structure and EcoQs between November and December in Gangjin Bay. Spearman correlation analysis and principal coordinates analysis (PCoA) demonstrated that the multivariate AMBI (M-AMBI) exhibited the best overall performance among indices. However, considering the ecological complexity, variability in farming practices, and site-specific conditions typical of shellfish aquaculture environments, the use of five benthic indices and a composite index is recommended to ensure a more comprehensive and robust evaluation of EcoQs in Korean shellfish farms. Full article

Two new subterranean species of the genus Spelaeogammarus da Silva Brum, 1975 in Serra do Ramalho municipality, Bahia state, and Montes Claros municipality, Minas Gerais state, both in Brazil, are described herein. With these additions, the genus now comprises ten known species. This study includes a comparative table detailing the diagnostic characteristics of all Spelaeogammarus species and an updated genus diagnosis. Additionally, it provides insights into the species’ habitats and the threats they face. Some of the type localities mentioned in this study are not within protected areas, making these species particularly vulnerable to environmental risks. Threats primarily arise from surrounding land use, which can impact the water table and disrupt food resource availability. The discovery of these new troglobitic species underscores the urgent need for their inclusion in future threatened species assessments and highlights the importance of conservation measures to protect both the species and their cave habitats, along with the surrounding landscape. Finally, the discovery of these new species highlights the remarkable diversity of Spelaeogammarus in subterranean environments, emphasizing the need for further research and conservation efforts. Full article

Barrow Island, off the coast of north-west Western Australia, supports a rich subterranean amphipod fauna amid major resource development. Previous biological surveys for the purpose of species documentation and environmental impact assessment have helped to uncover a once overlooked genus of amphipod from the family Eriopisidae. Here, we describe this new genus and one new species, Aenigmata megabranchia Stringer and King gen. et sp. nov., using a combination of molecular and morphological data, and present a key to Western Australian subterranean eriopisid genera. The new genus represents a distinct, genetically divergent lineage that can be distinguished from all other eriopisid genera by the following characters: the shape and setation of the mouthparts, the enlarged coxal gills, the straight posterior margin of the first coxa, and an almost entirely cleft telson. This research enhances our knowledge of the Australian Eriopisidae, emphasises the importance of Barrow Island as a key location for subterranean amphipod fauna, and will assist in the future recognition of the species for conservation. Full article

Solar ultraviolet (UV) is among the most important ecological factors shaping the composition of biota on the planet’s surface, including the upper layers of waterbodies. Inhabitants of dark environments recently evolving from surface organisms provide natural opportunities to study the evolutionary losses of UV adaptation mechanisms and better understand how those mechanisms function at the biochemical level. The ancient Lake Baikal is the only freshwater reservoir where deep-water fauna emerged, and its diverse endemic amphipods (Amphipoda, Crustacea) now inhabit the whole range from highly transparent littoral to dark depths of over 1600 m, which makes them a convenient model to study UV adaptation. With 10-day-long laboratory exposures, we show that adults of deep-water Baikal amphipods Ommatogammarus flavus and O. albinus indeed have high sensitivity to environmentally relevant UV levels in contrast to littoral species Eulimnogammarus cyaneus and E. verrucosus. The UV intolerance was more pronounced in deeper-dwelling O. albinus and was partially explainable by lower levels of carotenoids and carotenoid-binding proteins. Signs of oxidative stress were not found but UV-B specifically seemingly led to the accumulation of toxic compounds. Overall, the obtained results demonstrate that UV is an important factor limiting the distribution of deep-water amphipods into the littoral zone of Lake Baikal. Full article

A central goal of molecular studies on ancient lake faunas is to resolve the origin and phylogeny of their strikingly diverse endemic species flocks. Another equally intriguing goal is to understand the integrity of individual morphologically diagnosed species, which should help to perceive the nature and speed of the speciation process, and the true biological species diversity. In the uniquely diverse Lake Baikal amphipod crustaceans, molecular data from shallow-water species have often disclosed their cryptic subdivision into geographically segregated genetic lineages, but the evidence so far is mainly based on mitochondrial DNA. We now present a lake-wide parallel survey of both mitochondrial and multilocus nuclear genetic structuring in the common shoreline amphipod Eulimnogammarus verrucosus, known to comprise three deep, parapatric mtDNA lineages. Allele frequencies of seven nuclear allozyme loci divide the data into three main groups whose distributions exactly match the distributions of the main mitochondrial lineages S, W, and E and involve a further division of the W cluster into two subgroups. The inter-group differences involve one to four diagnostic loci and additional group-specific alleles. The transition zones are either abrupt (1 km), occur over a long segment of uninhabitable shoreline, or may be gradual with non-coincident clinal change at different loci. Mitochondrial variation is hierarchically structured, each main lineage further subdivided into 2–4 parapatric sublineages or phylogroups, and patterns of further local segregation are seen in some of them. Despite the recurring observations of cryptic diversity in Baikalian amphipods, the geographical subdivisions and clade depths do not match in different taxa, defying a common explanation for the diversification in environmental history. Full article

Numerous and diverse groundwater habitats suitable for sustaining aquatic invertebrate communities exist across Australia. These habitats include enclosed subterranean aquifer systems, fractured rock, alluvial aquifers, perched aquifers, artesian springs, and spring-fed seeps and marshes. Crustaceans are a dominant member of these groundwater-associated invertebrate communities, and amphipods, both stygobiont and associated epigean species, are particularly diverse yet are still relatively poorly known. We review both the diversity and distributions of Australian amphipods associated with groundwater habitats, describing hotspots of diversity, providing notes on the unique Australian habitats, and examining the extraordinary species diversity and endemism of the Australian species. Our review highlights the significance of Australian groundwater ecosystems, their associated biodiversity, and the importance in considering these ecosystems in groundwater conservation management plans. Full article

A synopsis of current knowledge of the diversity of the New Zealand landhopper fauna is provided. A combination of morphological and molecular analysis was employed on material from across New Zealand. Thirteen new endemic genera soon to be formally described have been discovered, including four belonging to the widespread families Talitridae and Arcitalitridae. These are families that had not been previously reported from New Zealand. We document the existence of at least 48 new provisional native species. This number far exceeds the 28 species currently described. Some described species are now shown to be species complexes, and a few of these are very diverse with numerous cryptic species. Six changes to the existing taxonomy are proposed. Dallwitzia simularis (Hurley, 1957) is transferred from Makawidae Myers & Lowry, 2020 to Talitridae Rafinesque, 1815; Kellyduncania hauturu (Duncan, 1994) is reinstated as a member of Dana Lowry, 2011; Kellyduncania (Lowry & Myers, 2019) is relegated to a synonym of Dana Lowry, 2011; Kanikania Duncan, 1994 is transferred from Makawidae Myers & Lowry, 2020 to Arcitalitridae Myers & Lowry, 2020; Parorchestia longicornis is transferred to Kanikania Duncan, 1994; Waematau kaitaia (Duncan, 1994) is transferred to Kohuroa Lowry, Myers & Nakano, 2019; and Waematau unuwhao (Duncan, 1994) is transferred to Omaiorchestia Lowry & Myers, 2019. This reduces the number of described New Zealand genera from 17 to 16. Full article

The characteristics of zooplankton communities and the relationships with the aquatic environment in the shallow waters of northern Liaodong Bay were investigated. Spot sampling surveys were carried out in April, June, September, and November 2018 to assess zooplankton species composition and diversity, abundance, biomass, and dominant species, and the associated relationships with environmental factors. A total of 45 species of zooplankton were recorded in the survey, comprising 18 Copepoda, 2 Amphipoda, 1 Mysidacea, 1 Decapoda, 1 Chaetognatha, 7 Hydrozoa, 1 Tunicate, and 14 planktonic larvae. Overall, the most dominant species was Aidanosagitta crassa (Tokioka, 1938), with copepods and planktonic larvae also dominating the zooplankton community. However, there was a seasonal alternation of species dominance. A cluster analysis showed that the zooplankton community in spring differed from other seasons and was mostly influenced by suspended particulate matter. Bioenv analysis indicated the main environmental factor affecting the zooplankton community in spring was suspended particulate matter. In summer, the determining variables were temperature, dissolved inorganic nitrogen (DIN), nitrate, and sediment pH. In autumn, temperature, DIN, and nitrate were determining variables, and dissolved oxygen (DO) and DIN in winter. Zooplankton abundance and biomass were influenced by salinity, suspended particulate matter, chemical oxygen demand (COD), chlorophyll, and water and sediment pH. In general, the shallow sea area north of Liaodong Bay is rich in zooplankton species and exhibits significant seasonal variations. Human activities have disturbed the biological community to a certain extent, and the environmental factors in this area are closely related to the diversity of zooplankton species. Full article

Seamounts can have a strong influence on the distribution and diversity of species, creating an oasis effect that may favour diversification. In order to assess how and to what extent supra- and epibenthic crustaceans can colonise these environments, the eucarid and peracarid fauna collected from the summit of the Valencia Seamount (VS), a small deep seamount (summit depth: 1056 m), rising from a depth of ca. 1850 m, in the oligotrophic Balearic Basin, was analysed. Based on a first sampling (beam trawls, plankton nets and stomach contents), and a faunal reconstruction from a sediment core (MC2, at 1151 m), the supra(epi)benthic crustaceans at the VS summit (to 1300 m) were composed of nine Eucarida and 25 Peracarida. Polycheles typhlops, Munida tenuimana, and Aristeus antennatus were the dominant species among eucarids. Among Peracarida the most abundant species were the Mysida Boreomysis arctica, the Amphipoda Rhachtropis caeca, and the Isopoda Munnopsurus atlanticus. Among Decapoda, a species with a wide amplitude in their depth distribution and small eggs (i.e., with planktotrophic larvae), showed a higher colonisation capacity. In the absence of larvae, the colonisation of peracarids depends on the amplitude of their depth distribution and only those species that reach the highest depths in the entire Balearic Basin, at least 1600–1800 m, were able to colonise the summit of VS. The natatory capacity of the species also has some influence and whole groups with low natatory capacity, such as the Desmosomatidae, were completely absent on the VS summit; however, they are distributed throughout the Balearic Basin to depths (up to about 1500 m) exceeding the depth of the seamount summit. Therefore, colonisation by peracarids must not have occurred by swimming through the entire water column, but by swimming along or just above the bottom. Remains of some suprabenthic species (mainly the isopod M. atlanticus) in MC2 and another core collected in NW Mallorca (MC3, 1114 m), i.e., out of the VS, showed how isopod diversity and size distribution changed historically. Also, after the 1960s, a decrease in primary production due to a decrease in rainfall and river runoff associated with river damming could have reduced the abundance of M. atlanticus. These types of historical studies can be useful in interpreting long-term changes in deep-sea communities and optimising the management of these vulnerable areas. Full article

During two expeditions to the seamounts in the Yap-Caroline area of the Western Pacific, a new genus, Phoxirostus gen. nov., in the family Laphystiopsidae Stebbing, 1899, is erected for two new species, P. longicarpus sp. nov. (type species) and P. yapensis sp. nov. The new genus can be distinguished from the other three laphystiopsid genera by the acute rostrum not overreaching the distal end of the first peduncular article of antenna 1, the outer plate of maxilla 1 bearing 10–11 spines, and the elongated carpus of pereopods 3–7 being distinctly longer than half the length of the propodus. Phoxirostus longicarpus sp. nov. differs from P. yapensis sp. nov. by the shape of the eyes and coxa 4, the presence of posterodistal protrusions on pleonite 1, and the number of posterodistal protrusions on pleonite 2. Generic analysis of one mitochondrial (COI) and one nuclear (H3) gene using maximum likelihood and Bayesian inference clarified the phylogenetic position of the Laphystiopsidae within the superfamily Iphimedioidea Boeck, 1871. Full article

Understanding phenotype variation is among the central topics in biology. We revise and reanalyze studies of the amphipod genus Niphargus to confront two potential mechanisms driving its phenotype variation, namely, cladogenesis and adaptive evolution. We found evidence for both mechanisms. Reanalysis of a subset of traits using molecular phylogeny showed moderate phylogenetic signal, consistent with the hypothesis that overall phylogenetic variation increases with phylogeny. The phylogenetic signal in Niphargus traits seems to be stronger at the tips of the phylogeny than at basal splits. Indirect evidence suggests that much of the phenotype variation can be attributed to adaptive evolution. Both lines of evidence are consistent with the hypothesis that Niphargus evolved in several adaptive radiations, where theory predicts that most of the phenotype variation evolves early, when ecological niches are vacant. As the niches fill up, the rate of phenotype variation slows down and becomes associated with cladogenetic events. This hypothesis can explain the high level of trait-convergence and unresolved taxonomy above the species level. The main caveats to these hypotheses comprise lack of experimental evidence for trait function and nonquantified heritable component of trait variation. Promising venues towards better understanding of phenotypic variation include studies of ontogenetic variation, functional interactions between traits, and genome–phenotype associations. Full article

Idunella spinifera (Dauvin and Gentil, 1983) (Crustacea: Amphipoda: Liljeborgiidae) is reported for the first time after the original description that was based on one immature female. Specimens were collected in the Ría de Muros (NW Iberian Peninsula) during the course of a study on macrofauna diversity in shallow sublittoral biogenic sands along a one-year period. The male and the ovigerous female are fully described, and the data on ecology and temporal variation of abundance is provided as well. Full article

A review and partial revision of the diversity of freshwater stygobiotic crustaceans in the territory of the Republic of North Ossetia–Alania, in the North Caucasus, is presented here. Previously, two species of the genus Proasellus Dudich, 1925 (Isopoda, Asellidae), P. uallagirus Palatov & Sokolova, 2020 and P. irystonicus Palatov & Sokolova, 2020, and one species of the genus Niphargus Schiödte, 1849 (Amphipoda, Niphargidae), N. alanicus Marin & Palatov, 2021, were described from the hyporhean/underground habitats (hyporhea) in the area. However, further research using an integrative approach has revealed that only a single species of the genus Proasellus (P. uallagirus) is actually widely distributed in the hyporhean riverbed habitats in the area, while the diversity of the genus Niphargus is higher than previously known. Six more new Niphargus species— namely, N. ardonicus sp. nov., N. sadonicus sp. nov., N. fiagdonicus sp. nov., N. tschertschesovae sp. nov., N. osseticus sp. nov. and N. zeyensis sp. nov., were discovered from the various hypogean underground water sources (i.e., springs and seeps) and are described in this article. Their phylogenetic relationships with their congeners, as well as their ecology and known distribution, are discussed. Furthermore, molecular genetic analysis, with an interpretation of the estimated divergence time, suggests that the studied hyporheic/stygobiotic crustaceans started to diverge from related European and Balkan sister species during the Late Miocene, approximately 8–5.8 Mya, with the reduction in the Paratethys and the uplifting of the Caucasus Mountains. Local speciation was led by local geological processes and karst fragmentation during the Late Pliocene and Early Pleistocene periods, starting around 5.3 Mya. The obtained data suggest that the mountainous area of the North Ossetia–Alania could be considered as a post-Pliocene glacial refugium for subterranean and stygobiotic fauna—the first known for the North Caucasus region. Full article

To elucidate how rising temperatures influence native amphipods, and how the expansion of wastewater treatment plants (WWTPs) with a fourth purification stage can alter temperature-related effects, studies were conducted in anthropogenically influenced rivers in Southwest Germany. Gammarids were sampled up- and downstream of two WWTPs, and exposed to elevated temperatures in the laboratory. Gammarids separated from precopula pairs were more sensitive to exposure-related stress and to a temperature increase than animals that were not in the reproductive phase. Furthermore, females were significantly more sensitive than males. Adult gammarids sampled individually at the WWTP with three purification stages showed a similar tolerance to elevated temperature at the up- and downstream site. In contrast, mortality following heat stress was substantially lower in animals sampled downstream of the WWTP with four treatment stages than in those sampled at the upstream site. We assume that the increased sensitivity of artificially separated precopula pairings reflect the situation under high hydraulic stress after heavy rainfall. Our results further illustrate the importance of WWTP upgrades in the context of climate change: gammarids sampled downstream the upgraded fourth-stage WWTP were likely exposed to lower levels of micropollutants, and thus may have allocated energy from detoxification to heat stress responses. Full article

Seventy-three male specimens of “Platorchestia platensis” from Japan were inspected on 13 morphological characters. Most characters revealed high variation. The coxa and propodus of gnathopod 2 and the carpus of pereopod 7 indicated that the specimens comprised two species: Platorchestia pacifica Miyamoto and Morino, 2004 and Demaorchestia joi (Stock and Biernbaum, 1994) sensu lato. Both species were rediagnosed. Demaorchestia hatakejima Lowry and Myers, 2022 was synonymized to P. pacifica. A key to allied species in Platorchestia and Demaorchestia from Japan and the surrounding countries was given. Full article