Peracarida Research Articles

Temporal and spatial dynamics of the non-indigenous bryozoan, Amathia verticillata, and its associated invertebrate community

The widespread non-indigenous bryozoan, Amathia verticillata primarily colonizes in coastal bays and harbors on anthropogenic structures. Although this habitat-forming bryozoan is widely recognized to house a variety of marine invertebrates within its structure, little is known about their spatiotemporal dynamics and their associated invertebrate community in Southern California, USA. Thus, we undertook a comprehensive yearlong study (July 2021-2022) in an urbanized estuary (Mission Bay, San Diego) to quantify A. verticillata percent cover and abiotic conditions at 6 stations with varying environmental conditions. The seasonal and spatial gradients in temperature and salinity within Mission Bay were as expected with seasonal hypersalinity typical of Mediterranean climate regions. The percent cover of A. verticillata was positively correlated with temperature with the highest percent cover found during the warmest periods, and higher average percent cover found in the warmer, eastern parts of Mission Bay. We also collected three replicate A. verticillata colonies to characterize the marine invertebrate community associated with this non-indigenous bryozoan. We identified 25 families, 24 genera, and 19 organisms to species belonging to the taxonomic groups: amphipods, isopods, tanaids, and polychaetes. Furthermore, we identified juvenile stages and ovigerous females living within A. verticillata. None of the identified invertebrate families contributed more than 21 % to the community. The seasonal growth and annual temporal patterns of A. verticillata may prevent competitively dominant species from becoming established within the invertebrate community and allow A. verticillata to harbor a diverse invertebrate community. Sphaeromatidae isopods were the most common family found in the bryozoan colonies, likely reflecting their broad environmental tolerances. Additionally, while some of the invertebrates found within A. verticillata were also non-indigenous species, more work needs to be done to determine if A. verticillata disproportionately supports these species over native species. Collectively, our results imply that A. verticillata functions as a nursery habitat on anthropogenic structures for peracarid crustaceans and polychaetes. Furthermore, A. verticillata assemble analogous communities across their distribution, which may indicate that invasions are homogenizing biota globally.

Phylogenomics supports a single origin of terrestriality in isopods.

Terrestriality, the adaptation to life on land, is one of the key evolutionary transitions, occurring numerous times across the tree of life. Within Arthropoda, there have been several independent transitions: in hexapods, myriapods, arachnids and isopods. Isopoda is a morphologically diverse order within Crustacea, with species adapted to almost every environment on Earth. The order is divided into 11 suborders with the most speciose, Oniscidea, including terrestrial isopods such as woodlice and sea-slaters. Recent molecular phylogenetic studies have challenged traditional isopod morphological taxonomy, suggesting that several well-accepted suborders, including Oniscidea, may be non-monophyletic. This implies that terrestriality may have evolved multiple times. Current molecular hypotheses, however, are based on limited sequence data. Here, I collate available genome and transcriptome datasets for 36 isopods and four peracarid crustaceans from public sources, generate assemblies and use 970 single-copy orthologues to estimate isopod relationships and divergence times with molecular dating. The resulting phylogenetic analyses support monophyly of terrestrial isopods and suggest conflicting relationships based on nuclear ribosomal RNA sequences may be caused by long-branch attraction. Dating analyses suggest a Permo-Carboniferous origin of isopod terrestriality, much more recently than other terrestrial arthropods.

A Latitudinal Cline in the Taxonomic Structure of Eelgrass Epifaunal Communities is Associated With Plant Genetic Diversity

ABSTRACTAimBiogenic structural complexity increases mobile animal richness and abundance at local, regional and global scales, yet animal taxa vary in their response to complexity. When these taxa also vary functionally, habitat structures favouring certain taxa may have consequences for ecosystem function. We characterised global patterns of epifaunal invertebrates in eelgrass (Zostera marina) beds that varied in structural and genetic composition.LocationNorth America, Europe and Asia.Time Period2014.Major Taxa StudiedPeracarid crustaceans and gastropod molluscs.MethodsWe sampled epifaunal invertebrate communities in 49 eelgrass beds across 37° latitude in two ocean basins concurrently with measurements of eelgrass genetic diversity, structural complexity and other abiotic and biotic environmental variables. We examined how species richness, abundance and community composition varied with latitude and environmental predictors using a random forest approach. We also examined how functional trait composition varied along with community structure.ResultsTotal species richness decreased with latitude, but this was accompanied by a taxonomic shift in dominance from peracarid crustaceans to gastropods, which exhibited different sets of functional traits. Greater eelgrass genetic diversity was strongly correlated with both richness and abundance of peracarids, but less so for gastropods.Main ConclusionsOur results add to a growing body of literature that suggests genetic variation in plant traits influences their associated faunal assemblages via habitat structure. Because peracarids and gastropods exhibited distinct functional traits, our results suggest a tentative indirect link between broad‐scale variation in plant genetic diversity and ecosystem function.

Ingolfiellids (Crustacea, Peracarida, Ingolfiellidea) from the Intra-Americas Sea with the description of a new deep-sea species of Ingolfiella from the southern Gulf of Mexico

The order Ingolfiellida (Crustacea, Peracarida) represents a small group of peracarid crustaceans, usually less than 3 mm long and comprising 53 species in several ecosystems worldwide. Previously, eight ingolfiellid species had been documented from the Intra-Americans Sea: one from the Gulf of Mexico and eastern Florida and seven from the Caribbean Sea, including the Bahamas. A new deep-sea species of Ingolfiella is described based on material collected from bathyal soft bottoms (2650 m depth) offshore Veracruz State, southern Gulf of Mexico. The new species can be differentiated as follows: accessory flagellum 2-articulate; antenna 2 flagellum 4-articulate; pereopods 5-6 with long curved seta on dactylus; rami of uropod 1 subequal in length; uropod 3 ramus longer than peduncle, unarticulated; pleopods 1-3 as long as pleonal segments; maxilla 1 inner plate with one tiny seta distally; mandible without palp; molar poorly developed; pleopods reduced; telson as a fleshy ovoidal lobe with two slender dorsal setae. A table and a map featuring the nine ingolfiellids recorded in the Gulf of Mexico, the Caribbean Sea, and eastern Florida are also provided. The new species increases the number of Ingolfiella species to 35 worldwide, representing the second record of ingolfiellids from the Gulf of Mexico.

Discovery of deep-sea cold seeps from Argentina host singular trophic linkages and biodiversity

Chemosynthetic ecosystems host unique geological, biogeochemical, microbial and faunistic settings, which provide key ecosystem services for human wellbeing. In the Argentine continental margin, the existence of chemosynthetic ecosystems is still unknown. We present the first finding of chemosynthetic ecosystems in the Argentine deep sea. We assessed and compared biological and geological settings for cold seeps at Malvinas Basin and Colorado Basin and a control site (no gas) at Colorado Basin. We found two cold seeps with crater-like geomorphic features (pockmarks) of 500-m and 1000-m diameter at depths of ⁓500 m. Both cold seeps exhibited methane gas bubbles trapped at the surface of the seafloor, one exhibited seepage into the water column. Cold seeps hosted dense benthic macroinvertebrates (≥300 μm) assemblages consisting mainly of polychaetes, peracarid crustaceans and mollusks. The fauna from Argentinean seeps exhibited δ13C and δ15N stable isotope signatures indicative of multiple trophic levels, supported by both chemosynthetic and photosynthetic sources of energy. The difference in bubbling to the water column was not associated with different trophic input of chemosynthetically-derived sources of energy, suggesting that gas input is mediated by the bubbles trapped in the seafloor sediments. The presence of gas bubbles trapped in the surface sediments of the ocean floor allowed the detection of ecological and trophic characteristics of active chemosynthetic ecosystems. Integration of the sub-bottom dimension can help improve our understanding of the interactions of chemosynthetic ecosystems with seafloor fluid flow in a more reliable manner than the gas plumes. These cold seeps host significant biodiversity and ecosystem functions of the deep ocean. They fall within areas tendered for oil and gas industry development, but have not been a focus of conservation efforts to date. Information provided here can inform effective conservation actions and improve our understanding of the distribution of chemosynthetic ecosystems worldwide.

An annotated checklist of the Amphipoda (Crustacea) of the Iraqi coast, north-western Persian- Arabian Gulf

Amphipods are one of the most diverse groups of peracarid crustaceans, living in both marine and fresh waters, including underground and semi-terrestrial settings. Data about amphipods from the Iraqi coast are spread throughout valid published and confused published references. So, a checklist of the amphipods of the Iraq coast is presented listing 8species belonging to six families, using published records and field observations. The present paper shows that the list of amphipoda from the Iraqi coast is very limited compared with lists of other adjacent countries on the Persian-Arabian Gulf close to Iraq.

A case study on the function of turf algae as suitable habitat for peracarid crustaceans in disturbed environments from SW Mediterranean Sea

ABSTRACT In the summer of 2014, a field study was carried out in four coastal rocky bottoms from the southeast coast of Spain. In this region, dense canopies of Ericaria mediterranea characterize the undisturbed areas and cover much of the infralittoral stage. Turfs composed of the coralline algae Ellisolandia elongata replace the canopy in places where any anthropogenic disturbance occurs. The main objective of this study was to compare the peracarid fauna inhabiting within the two types of phytal substrate, and to conduct several statistical analyses to detect significant differences between the two assemblages. Contrary to expected, the analyses showed that in E. elongata there was a higher population density of peracarids, as well as higher species richness and values for α-diversity indexes. However, none of these differences was statistically significant, although site-to-site comparison indicated greater differences between locations with the same physical cover. The data pointed out that the assemblage that inhabits the coralline turfs in the area was not an impoverished version of that found in pristine locations, so these algae can act as a suitable habitat for peracarids in case of mild human disturbance.

Biological and functional responses of the benthic surf zone community to different beach types

In this study, we analyzed the biological descriptors and functional traits of the benthic community inhabiting the water/bottom layer in the surf zones of three sandy beaches: a tide-dominated flat, and two intermediate beaches, from tide-modified to wave-dominated. Samples were collected seasonally in the inner surf zone by hand-towing a benthic sledge equipped with two nets, one above the other, across transects parallel to the shore, capturing the benthic community in two levels, close to the seafloor. A total of 116 species were collected, with a total of 327,678 specimens. Arthropods were 99.63% of all individuals caught across the three beaches, mainly represented by peracarid crustaceans. An important species turnover was detected along the shore, with a significant change in community composition. The biological descriptors and some functional traits vary among beaches: the total density, the density of individuals of small (5–10 mm length) and very small sizes (<5 mm length), the density of larval forms, and the presence of colonial species were higher in the tide-dominated flat (sometimes also in the tide-modified beach). More arthropods and more mobile individuals were found in those beaches, while mollusks and sedentary individuals were found in high number in the wave-dominated beach. Stratification was present across the three studied beaches, with higher densities in the near-bottom layer. In the tide-dominated beach, there was also a higher richness in this layer, with a nested community between levels. In the wave-dominated beach, similar richness was registered between levels, with a different community composition (and some differences in functional traits), indicating that some species can maintain their position close to the bottom despite the turbulent conditions experienced on this beach. Differences in wave conditions among beach types could be an important factor driving the biological descriptors and functional traits of the benthic community in surf zone ecosystems. Therefore, acknowledging their role is crucial in deciphering global patterns in surf zone biodiversity.

The role of habitat heterogeneity and timescales on the recovery of reef epifaunal communities affected by a massive oil spill in the tropics

From August 2019 to January 2020 the Brazilian Coast was impacted by the largest oil spill in the Tropical oceans ever since. Paiva Beach, one of the most preserved sandy beaches in the northeast tropical Brazilian coast, was among the most affected regions by the oil spill in October 2019. This area has important reef systems that harbor abundant macroalgal assemblages with very diverse epifaunal communities. The present study aims to evaluate the impacts of the 2019 oil spill on epifauna associated with the seaweed species Jania capillacea and Penicillus capitatus collected in Paiva Beach from July 2019 to October 2022, and use the interaction macroalgae/epifauna/timescale as a proxy to quantify the effects of oil spills on communities structure and recovery. The epifauna of both algae did not suffer severe changes in abundance immediately after the spill, however, the abundance of taxa like echinoderms, sea spiders (Pycnogonida) and peracarid crustaceans dropped during or soon after the event, whereas others, like sabellid worms, had strong increase in abundance, possibly related to the spill. Both phytal assemblages also had distinct temporal patterns in species diversity and abundance, the last being strongly correlated to amphipod abundance for some taxa. The epifauna of J. capillacea had a short-term tendency of decrease in taxonomic diversity, whereas the epifaunal communities of P. capitatus gained a few taxa in the months immediately after the disaster. The diversity profiles of both communities returned to pre-spill conditions a few months later, with a slower abundance recovery in J. capillacea. Local environmental characteristics like landscape heterogeneity, connectivity with other environments, and critical-species (mainly amphipods) were possibly the main buffering factors for the phytal communities after the oil spill.

Seznam izopodov (Crustacea: Isopoda) v Sloveniji

Isopods are a diverse peracarid crustacean group with marine, freshwater and terrestrial representatives. Isopod species lists were typically prepared according to different habitats, which was true also for Slovenia. Here, we prepared the first unified overview of isopod species for Slovenia, which is also the first list of marine isopods in the country. We examined scientific publications, research reports and institutional databases. A total of 126 species have been recorded in Slovenia, of which 31 are marine, 21 are found in freshwater, and 74 are terrestrial. Of these, we report on seven marine and one terrestrial species for the first time. A major part of freshwater isopod richness is linked to the subterranean environment, where most endemic species for the country can be found. Among marine species, many are parasites, with potential economic impact, and two species are considered introduced. When the new species list is considered with valid national legislation, only 41 species retained the same taxonomic status. Many synonyms and invalid taxa according to recent taxonomy point out the need for revision the national red list of Malacostraca as well as other nature protection acts.

Shedding light on the Ophel biome: the trans-Tethyan phylogeography of the sulfide shrimp Tethysbaena (Peracarida: Thermosbaenacea) in the Levant.

Tethysbaena are small peracarid crustaceans inhabiting extreme environments such as subterranean lakes and thermal springs, represented by endemic species found around the ancient Tethys, including the Mediterranean, Arabian Sea, Mid-East Atlantic, and the Caribbean Sea. Two Tethysbaena species are known from the Levant: T. relicta, found along the Dead Sea-Jordan Rift Valley, and T. ophelicola, found in the Ayyalon cave complex in the Israeli coastal plain, both belonging to the same species-group based on morphological cladistics. Along the biospeleological research of the Levantine subterranean fauna, three biogeographic hypotheses determining their origins were proposed: (1) Pliocenic transgression, (2) Mid-late Miocenic transgression, and (3) The Ophel Paradigm, according to which these are inhabitants of a chemosynthetic biome as old as the Cambrian. Tethysbaena specimens of the two Levantine species were collected from subterranean groundwaters. We used the mitochondrial cytochrome c oxidase subunit I (COI) gene and the nuclear ribosomal 28S (28S rRNA) gene to establish the phylogeny of the Levantine Tethysbaena species, and applied a molecular clock approach for inferring their divergence times. Contrary to the morphological cladistic-based classification, we found that T. relicta shares an ancestor with Tethysbaena species from Oman and the Dominican Republic, whereas the circum-Mediterranean species (including T. ophelicola) share another ancestor. The mean age of the node linking T. relicta from the Dead Sea-Jordan Rift Valley and Tethysbaena from Oman was 20.13 MYA. The mean estimate for the divergence of T. ophelicola from the Mediterranean Tethysbaena clade dated to 9.46 MYA. Our results indicate a two-stage colonization of Tethysbaena in the Levant: a late Oligocene transgression, through a marine gulf extending from the Arabian Sea, leading to the colonization of T. relicta in the Dead Sea-Jordan Rift Valley, whereas T.ophelicola, originating from the Mesogean ancestor, inhabited anchialine caves in the coastal plain of Israel during the Mid-Miocene.

Facilitation of macrofaunal assemblages in marinas by the habitat-forming invader Amathia verticillata (Bryozoa: Gymnolaemata) across a spatiotemporal scale

Widespread habitat-forming invaders inhabiting marinas, such as the spaghetti bryozoan Amathia verticillata, allow exploring facilitation processes across spatiotemporal contexts. Here we investigate the role of this bryozoan as habitat for native and exotic macrofaunal assemblages across different ecoregions of Western Mediterranean and East Atlantic coasts, and a monthly variation over a year. While only 7 (all peracarid crustaceans) of the 54 associated species were NIS, they dominated macrofaunal assemblages in terms of abundance, raising the potential for invasional meltdown. NIS richness and community structure differed among marinas but not among ecoregions, highlighting the importance of marina singularities in modulating facilitation at spatial scale. Despite facilitation did not depend on bryozoan abundance fluctuations, it was affected by its deciduous pattern, peaking in summer and disappearing in late winter. Monitoring A. verticillata in marinas, especially in summer periods, may improve the detection and management of multiple associated NIS.

The Tanaidacea challenge to invasion science: taxonomic ambiguities and small size result in another potential overlooked introduction to the Iberian coast and nearby areas

A major challenge in invasion science is detecting overlooked introductions, their pathways of introduction and spread. One of the most successful introduced taxa in aquatic ecosystems are peracarid crustaceans. There are a growing number of reports of accidental introductions of peracarids worldwide, mostly related to human transport hubs (e.g., ports and marinas). Tanaidaceans are especially abundant in these communities. Most frequently given examples of natural and anthropogenic passive dispersers belong to the family Tanaididae. However, their wide distribution requires confirmation. Most records come from 70–80’ of last century, when identification of the species relied only on morphological characters. The small size and large intraspecific variation of tanaidids generate a high taxonomic uncertainty, as in the case of Zeuxo turkensis. Population of this species was previously known from Turkish, Japanese, and Australian coasts. In the two last places this tanaidid was identified as Hexapleomera sasuke, despite there were some premises that it should be synonymized with Z. turkensis. Here we investigate specimens that resembled both Hexapleomera sasuke and Zeuxo turkensis collected in marinas around the Iberian and Moroccan coasts. Integrating morphological and molecular methods (barcoding) we confirmed: (1) the first record and presence of well-structured populations of Z. turkensis in Spain, Portugal and Morocco, representing the first record of the species for Atlantic waters; (2) the conspecificity between H. sasuke and Z. turkensis, which should be synonymized; and (3) the wide distribution of Z. turkensis associated with human transport hubs (i.e. marinas) in the study area, showing its potential for introduction and spread. Integrated approaches and greater taxonomic support are key to advancing knowledge on the origin and invasion patterns of this and other small and poorly known human-mediated widespread species.

Diet variations of Striped Piggy, Pomadasys stridens (Forsskål, 1775) (Teleostei: Haemulidae) in the northeastern Mediterranean Sea

The opening of the Suez Canal started an influx of non-indigenous species into the Mediterranean Sea, yet mechanisms allowing for an introduced species to adapt and thrive are still a topic of debate. Since its recent introduction, the Striped piggy (Pomadasys stridens) has rapidly become one of the most abundant species on the eastern Mediterranean coast. However, no study has investigated feeding biology in its relatively new environment. We predicted the species to have a wide-ranged and flexible diet, contributing to its establishment success. We examined the stomach content of P. stridens in Mersin, Turkey, and assessed external parameters (depth and month) and biological indicators (spawning state and stomach fullness) as factors affecting diet composition. Our findings showed the species to mainly feed on crustaceans (predominantly copepods), followed by annelids (polychaetes and oligochaetes). Sexual maturity affected the diet: once mature, individuals switched from a copepod-based diet to higher trophic level-prey (decapods, peracarid crustaceans, and teleosts). Depth also affected the diet; polychaetes started playing a role in the stomach content below 50 m, whereas copepods were rather prominent for specimens in shallow waters (0–50 m). Stomach fullness, as a factor, showed that poorly fed specimen had a more diverse diet, while well fed specimen mostly preyed on copepods. Our results show P. stridens to have a relatively wide-ranged and adaptive diet which most likely contributes to the establishment of P. stridens in the eastern Mediterranean. Given the lack of fishing pressure and known predators in the region, we recommend close monitoring of the ongoing spread of P. stridens.

Glacier retreat effects on the distribution of benthic assemblages in Martel Inlet (Admiralty Bay, Antarctica).

The Antarctic environment has special characteristics that influence the local marine life. The benthic organisms, adapted to these extreme conditions of life, are subject nowadays to effects of climate change. Recently, the consequences of glacier retreat on these assemblages have been observed in many West Antarctic Peninsula (WAP) regions, including King George Island (KGI). This study described the spatial variation of the benthic macrofauna in different areas of the Martel Inlet (Admiralty Bay - KGI), at depths around 25-30 m. Sampling was done in January 2001 at ten stations classified in localities according to their proximity to ice-margin/coastline in marine-terminating glacier (MTG), terrestrial-terminating glacier (TTG) and ice-free area (IFA). The total density and the abundance of annelids, nematodes, peracarid crustaceans and bivalves were higher at IFA stations. The locality discrimination by taxa and species was independent of available environmental/sedimentary conditions or was the result of unmeasured variables or species life history processes not assessed herein. Considering that our findings were obtained 21 years ago, they will be especially useful for comparing future studies of benthic assemblage responses to the influence of climate change and continuous glacier retreats in the WAP region.

Richard W. Heard (February 14, 1939 &amp;ndash; November 2, 2022)

Professor Dr. Richard Willis Heard, a longtime and outstanding collaborator of the &amp;ldquo;Grigore Antipa&amp;rdquo; National Museum of Natural History of Bucharest, passed away on November 2, 2022. Richard was born on February 14, 1939 in Savannah, Georgia (USA). He was a graduate of Savannah Country Day School and attended the University of Georgia, receiving his BS and MS degree in Zoology. He received his PhD degree in Biology at the University of Southern Mississippi (1976). He worked for more than 35 years at the Gulf Coast Research Laboratory (The University of Southern Mississippi), passing through various hierarchical steps, up to that of Head of the Invertebrate&amp;nbsp;Zoology Section. He was drawn to know the marine invertebrates of the Gulf of Mexico, Caribbean Sea, and western Atlantic Ocean. His research focused primarily on the study of peracarid crustaceans. Also he mentored many students and young researchers specializing in marine biology.

Diversity of and biogeographic insights into the Atlantic Eocuma (Cumacea: Peracarida)

The Gulf of Guinea is characterised by a complex hydrology and supports a high species diversity. A recent study has indicated that the area can be considered a refuge for rare taxa. Intensive sampling off the coast of Ghana (Gulf of Guinea) in 2012 on board the R/V F. Nansen resulted in the discovery of a large number of benthic invertebrates, including peracarid crustaceans. A preliminary investigation demonstrated a high diversity of the Cumacea, with 95% of the species being new to science. The most species-rich genus was Eocuma with seven species; six of them proved new to science and are described here. Additionally, the global distribution of Eocuma was analysed with the help of a phylogenetic tree based on morphological characters, Bayesian Binary Markov chain Monte Carlo biogeographic analysis and literature data. The radiation centres of the west African fauna are discussed.

Challenges and Advances in the Taxonomy of Deep-Sea Peracarida: From Traditional to Modern Methods

As one of the oldest branches of biology, taxonomy deals with the identification, classification and naming of living organisms, using a variety of tools to explore traits at the morphological and molecular level. In the deep sea, particular challenges are posed to the taxonomic differentiation of species. Relatively limited sampling effort coupled with apparent high diversity, compared to many other marine environments, means that many species sampled are undescribed, and few specimens are available for each putative species. The resulting scarce knowledge of intraspecific variation makes it difficult to recognize species boundaries and thus to assess the actual diversity and distribution of species. In this review article, we highlight some of these challenges in deep-sea taxonomy using the example of peracarid crustaceans. Specifically, we offer a detailed overview of traditional as well as modern methods that are used in the taxonomic analysis of deep-sea Peracarida. Furthermore, methods are presented that have not yet been used in peracarid taxonomy, but have potential for the analysis of internal and external structures in the future. The focus of this compilation is on morphological methods for the identification, delimitation and description of species, with references to molecular analysis included where relevant, as these methods are an indispensable part of an integrative taxonomic approach. The taxonomic impediment, i.e. the shortage of taxonomists in view of a high undescribed biodiversity, is discussed in the context of the existing large taxonomic knowledge gaps in connection with the increasing threat to deep-sea ecosystems. Whilst peracarid crustaceans are used here as an exemplary taxon, the methodology described has broad relevance to many other deep-sea taxa, and thus will support broader research into deep-sea biodiversity and ecology more widely.

Contribution of alien peracarid crustaceans to the biocontamination of benthic macroinvertebrate assemblages in Croatian large rivers

Peracarid crustaceans (orders Amphipoda, Isopoda and Mysida) are one of the most important groups of invaders in fresh and brackish waters. Although large rivers in Croatia have been heavily invaded by peracarid crustaceans, little is known about their impact on local benthic macroinvertebrate assemblages. The main aim of this study was to investigate the contribution of alien Peracarida to the biocontamination of macroinvertebrate assemblages in Croatian large rivers as a proxy measure of their impact. Quantitative sampling was conducted twice (2015 and 2016/2017), at 48 sites on four large rivers (Danube-4, Sava-21, Drava-20, Mura-3). Physicochemical parameters were measured eight times during 2015 and 2016. In total, 16 species were recorded, five native and 11 alien species. The highest number (10 alien species, most from genus Dikerogammarus and Chelicorophium) were found in the Danube River, while subsets of alien species were found in the Sava (5 spp.) and Drava Rivers (6 spp.), and no alien species were found in the Mura River. The most upstream reaches of the Mura, Drava, and Sava Rivers in Croatia have not yet been colonized by invasive peracarids and the native peracarids are still abundant there. In the Drava River, alien Peracarida had the highest densities. Significant negative correlations were established between the number of native taxa and alien Peracarida species. Proportions of alien peracarids in the total density of benthic macroinvertebrates were spatially variable, the highest average values in the Drava River (24.4 %), and lower in the Danube (20 %) and the Sava (17.7 %) Rivers. Alien Peracarida had the most important contribution to the richness and abundance contamination of macro¬invertebrate assemblages. The upstream spread of invasive peracarids will increase biocontamination and could cause a decline of native species richness and abundance in the most upstream reaches of the Sava and Drava Rivers. To prevent further up¬stream spread of alien Peracarida, “check, clean and dry” protocols should be included in the national regulations.

First multigene phylogeny of Cumacea (crustacea: Peracarida)

AbstractCumaceans are small peracarid crustaceans that can be remarkably diverse and important benthic organisms. Despite their ubiquitous presence in soft sediments, no well‐resolved phylogeny currently exists, which impedes ecological and evolutionary studies of the group. We present a phylogeny based on Bayesian inference of six markers (18S, 28S, 12S, 16S, CytB and COI), which recovers monophyly of the order, a deep split between telson and pleotelson bearing groups, and monophyly of four of the seven included families, including monophyletic Pseudocumatidae, Lampropidae, Bodotriidae and Nannastacidae. The only species representing the family Gynodiastylidae in our dataset was positioned among members of Diastylidae in the phylogenetic analyses. However, this result is based on a single partial COI sequence; thus, we consider it doubtful, and the family Diastylidae are otherwise recovered as a monophyletic family. The family Leuconidae is split into two well‐supported clades, a clade containing Antarctic members of the genus Leucon and a separate clade containing non‐Antarctic members of the genera Leucon and Eudorella. The phylogeny is a great stride forwards, as it supports most families as monophyletic, making generic level phylogenies a plausible endeavour in the future.