Abundance Of Benthic Invertebrates Research Articles

Full year seasonality of benthos in the nearshore of Lake Superior

Relatively little is known about the full-year dynamics of benthic invertebrates in seasonally-freezing lakes. In this study, we describe the seasonal variability in benthic invertebrate abundance and coarse-level taxonomic composition across five nearshore locations in Lake Superior, with a focus on the winter period. We found that benthos abundances were relatively stable across the year, with similar winter (2294 ± 987 SD ind. m−2) and summer densities (2710 ± 1445 SD ind. m−2) across all stations. Community composition was also relatively stable across the year at our study stations, with Hexagenia sp., chironomids, and oligochaetes dominating our shallowest station (Duluth Harbor) and oligochaetes, Diporeia sp., and clams (Sphaeriidae) dominating deeper locations. Across all stations, diversity was similar across seasons, with the highest number of taxa observed in the fall (5.4 ± 1.8) and lowest number in the summer (4.5 ± 1.4). We found that the winter-spring period was an important time for the reproduction of the Lake Superior keystone amphipod Diporeia sp. Finally, we show that community structure was more variable across sites than across seasons. This is one of very few studies of winter benthos in the Great Lakes and suggests that benthic invertebrate communities show muted seasonal variability compared to planktonic organisms.

Nearshore subtidal community response during and after sediment disturbance associated with dam removal

Dam removal is used increasingly to restore aquatic ecosystems and remove unnecessary or high-risk infrastructure. As the number of removals increases, there is a growing understanding about the hydrologic, geomorphic, and ecological responses to these removals. Most dam removal studies, however, focus on river and watershed responses to dam removal. The removal of two dams on the Elwha River provided a unique opportunity to characterize the response of nearshore (coastal) ecosystems. We conducted SCUBA surveys between 2011 and 2022 to quantify trajectories of change in a nearshore ecosystem during and after dam removal. We focused on the degree to which the abundances of kelp, benthic invertebrates, and fish changed in response to patterns of sediment fluxes during and after dam removal. Our findings point to two pathways of response depending on the disturbance mechanism and species type. Sites with persistent sediment deposition were characterized by wholesale community changes that did not recover to a before dam removal condition. Instead, the sites were colonized by new species that were largely absent prior to dam removal. Sites that experienced high turbidity but lacked persistent seafloor deposition were primarily characterized by a reduction in the abundance of kelp and other algae during dam removal and a rapid recovery after sediment flux to the nearshore declined. Dam removal influences on invertebrates and fish at these sites were more variable, benefiting some species and disadvantaging others. In addition to dam removal, sea star wasting syndrome and a marine heatwave exerted distinct controls on subtidal communities during the same period. The loss of the predatory sea star Pycnopodia helianthoides was associated with gains in some of its prey species, and kelp community changes reflected regional trends in ocean temperature and kelp abundance. The results presented here have important implications for understanding the response of marine ecosystems to future dam removals and similar sediment perturbation events.

MACROINVERTEBRATES THE FOOTHILL LAKES OF THE NORTHERN AND NORTHEASTERN ALTAI

The taxonomic composition and abundance of benthic invertebrates in four lakes (Aya, Kireevo, Koksha and Svetloye) of the northern and northeastern Altai were studied in May, July and September 2022. 126 species from 9 classes of invertebrates were identifi ed in the macrozoobenthos of the studied lakes. Lakes Aya and Kireevo are characterized by low species diversity, abundance and biomass of benthic invertebrates. According to the composition and structure of communities of benthic invertebrates, lakes Aya and Kireevo were close to fl atland and low-mountain lakes. High taxonomic diversity and abundance of macroinvertebrates in lakes Koksha and Svetloye were noted. The bottom population of these lakes had features of both fl atland and mountain lakes.

Integrating ocean observations across body‐size classes to deliver benthic invertebrate abundance and distribution information

AbstractInvertebrate animals living at the seafloor make up a prominent component of life globally, spanning 10 orders of magnitude in body size over 71% of Earth's surface. However, integrating information across sizes and sampling methodologies has limited our understanding of the influence of natural variation, climate change and human activity. Here, we outline maturing practices that can underpin both the feasibility and impact of establishing Benthic Invertebrate Abundance and Distribution as a Global Ocean Observing System—Essential Ocean Variable, including: (1) quantifying individual body size, (2) identifying the well‐quantified portions of sampled body‐size spectra, (3) taking advantage of (semi‐)automated information processing, (4) application of metadata standards such as Darwin Core, and (5) making data available through internationally recognized access points. These practices enable broader‐scale analysis supporting research and sustainable development, such as assessments of indicator taxa, biodiversity, biomass, and the modeling of carbon stocks and flows that are contiguous over time and space.

Effects of turbidity and introduced tilapia (Oreochromis spp) on macrophytes and invertebrates in a shallow tropical lake

Tropical freshwater wetlands are subject to multiple stressors but there is little information on which stressors cause wetland degradation. Increased turbidity is considered a major cause of degradation, but the effects of introduced fish are often overlooked. Tilapia are frequently introduced in tropical regions, especially species in the genus Oreochromis, and the ecological effects of introducing tilapia are poorly studied. We used enclosure experiments in a shallow lake in Madagascar to assess the effects of tilapia and turbidity on macrophytes and benthic invertebrates, and to test management interventions designed to increase both. Tilapia at high and low stocking densities had negative effects on survival of Charophyte algae and water lilies, but no direct effect on benthic invertebrate abundance or diversity. Invertebrate abundance was highest on submerged Charophytes, so herbivory by tilapia indirectly affected invertebrates. Turbidity affected Charophyte survival, and abundance and diversity of non-Dipteran insects. As a complication, tilapia may increase turbidity by re-suspending the lake sediment. Our results suggest that herbivory by tilapia is a plausible cause of the removal of macrophytes from the lake and an impediment to their re-establishment. Tilapia are widely introduced in tropical areas as a food resource. Our results demonstrate serious consequences to these introductions.

Subtle ecosystem effects of microplastic exposure in marine mesocosms including fish

For two months, communities in 5.8 m3 outdoor marine mesocosms were exposed to 700 μm sphere-shaped polystyrene (PS) beads in dosages between 0.08 and 80 g/m2. Barnacle (Semibalanus balanoides) densities were reduced at dosages of 0.8 g/m2 onwards without following a standard dose response curve. Lugworms and fish (Solea solea) ingested PS-beads without accumulating them. Lugworms (Arenicola marina) ingested the beads nonselective with the sediment without negative effects. The fish seemed to ingest the plastics only occasionally and at the final sampling day even in the highest dosed mesocosms (>30 beads/cm2) only 20% contained plastic. The condition index of the fish was slightly reduced in mesocosms with dosages of 0.8 g/m2 onwards. No difference in condition was found between fish with and without ingested plastic across mesocosms, illustrating the difficulty to relate plastic ingestion with condition from field data. The fish also ingested mollusks with shells exceeding the size of the PS-beads. Bivalves rejected the PS-beads as pseudofeces, without obvious impact on their condition. Mussel's (Mytilus edulis) pseudofeces present an effective matrix to monitor microplastic presence in the water column. Species richness and diversity of the pelagic and benthic community were not affected although, a trend was found that the lower microplastic dosages had a positive effect on the total abundance of benthic invertebrates. In general, the observed effects at even the highest exposure concentrations were that subtle that they will be obscured by natural variation in the field. This underlines the importance of experiments under semi-field conditions for meaningful assessment of the ecological impact of microplastics. This study was performed with the real life, non-toxic, sphere-shaped polystyrene beads as were lost during an actual spill near the Dutch Wadden sea in January 2019. We recommend future mesocosm studies with other types of microplastics, including microfibers, weathered microplastics from sea, and smaller sized particles down to nanoplastics.

ASSESSMENT OF THE CORAL REEF HABITATS, DAMAGE INDICATORS AND CORALS-REEF FISH RELATIONSHIP IN WADI EL-GEMAL NATIONAL PARK, RED SEA, EGYPT

Because of the pivotal role of the substrate composition in the ecological state of coral reef communities, the present study was attempted to investigate the substrate cover, coral reefs, and reef fishes in the marine ecosystem of the Wadi El-Gemal National Park (WGNP), Red Sea, Egypt. The surveys were conducted in the Spring and Autumn of 2015 by SCUBA diving and/or snorkeling. We applied the Point, Line, and Belt Intercept Transect (PIT, LIT and BLT) methods, to assess the state and forms of the substrate, through a quantitative assessment of the fundamental components of the benthic cover. A quantitative assessment was conducted on five main benthic categories at WGNP; hard corals, soft corals, dead corals, sand, and rocks. Six invertebrate groups; banded coral shrimp, sea urchin, sea cucumber, the crown of thorn, giant clam, and Drupella sp. were also investigated. The study showed that, while there was no significant difference between sites in the benthic structure and cover, sites were different in the cover of hard coral, the abundance of benthic invertebrates, and the abundance of reef fishes. We also, assessed the status of eight impact indicators of reef damage (or damage indication categories); old dead, recently dead, total bleached, partial bleached, diseased, broken, fragments, and recruitments of corals at the marine protected area as well as investigated the coral reef/reef fish community relationship. Among the eight reef impact indicators that were assessed in the current study, the old dead corals showed the highest cover of the substrate. In the same context, the cover of the diseased colonies was lower than other categories in the area of the study. The study also indicated that increasing hard coral cover in the study area had strongly affected the abundance of reef fishes. Nevertheless, the abundance of reef fishes was found to be increased with the increase of the hard coral cover (P < 0.05, r = 0.8), and this trend was attained by all reef fish families, the highest sites in coral cover and fish abundance were: Hnakourab, Wadi Lahmy and Sharm El-Luli (32, 28 and 25%, and 9, 11 and 6 mean number of fish/20 m transect), respectively. Positive correlation between the hard coral cover and fish abundance was detected as well. Acanthuraidae displayed the highest mean number of individuals (53.25/20 m belt transect). The study concluded that there is a need to perform a periodic assessment of the benthic cover of the main components of coral reef communities. Also, the study emphasized the role of benthic substrate structure and cover in the reef fish ecology.

Impacts of piscicide-induced fish removal on resource use and trophic diversity of lake invertebrates

Chemical eradication of non-native species has become a widely used method to mitigate the potential negative impacts of altered competitive or predatory dynamics on biodiversity and natural ecosystem processes. However, the responses of non-target species can vary from rapid full recovery to delayed or absent recolonization, and little is known about the potential shifts in resource use and trophic diversity of native species following chemical treatments. We used a before-after-control-impact approach to study the effects of rotenone piscicide treatment on abundance and trophic niche of benthic invertebrates in three untreated and three treated lakes in central Norway, the latter group hosting non-native roach (Rutilus rutilus) and pike (Esox lucius) prior to rotenone treatment. Based on community composition data, the relative abundance of invertebrate grazers and collectors decreased while that of predators increased following fish removal in the treated lakes. The stable isotope data indicated minor shifts in resource use of, and trophic diversity among, benthic invertebrate communities. While the predatory dragonfly larvae (Odonata) and grazer snails (Lymnaeidae) showed increased δ13C values indicating increased reliance on littoral benthic algae, the collector mayfly larvae (Leptophlebia) showed decreased δ13C values following fish removal in treated lakes. Grazer snails also showed a shift to a lower trophic position, while the predatory dragonflies and collector mayflies showed no changes in δ15N values following fish removal. The community-level isotopic niches of benthic invertebrates showed no consistent changes, although the sample-size corrected and Bayesian estimates of standard ellipse areas (SEAC and SEAB) slightly increased in two of the three treated lakes due to an increased range in δ15N. In conclusion, our study findings indicate some changes in species assemblages but minor shifts in the resource use and trophic diversity of benthic invertebrate communities following fish removal in rotenone treated lakes.

Non-native Dreissena associated with increased native benthic community abundance with greater lake depth

Although the typical interaction between non-native invasive species and native species is considered to be negative, in some cases, non-native species may facilitate native species. Zebra and quagga mussels (Dreissena spp.) are aggressive invaders in freshwater systems, and they can alter energy flow by diverting nutrients from pelagic to benthic food-webs. In the last two decades, quagga mussels have largely replaced zebra mussels in shallow regions of the Laurentian Great Lakes and colonized deeper waters previously devoid of all dreissenids. Here, we aim to characterize potential positive effects of dreissenids in relation to depth on the benthic community in lakes Michigan and Huron. For this study, we used benthic survey data collected from Lake Michigan in 2015 and Lake Huron in 2017 and annual U.S. EPA Great Lakes National Program Office Long-term Biology Monitoring Program data for both lakes from 1998 to 2019. Benthic species richness and abundance (excluding dreissenids) in both lakes were almost three-fold higher in the nearshore (<70 m) compared to offshore (>70 m) communities. We found that, even though abundance of benthic invertebrates decreased with increased depth, total benthos density and biomass were higher in the presence than in the absence of quagga mussels in both lakes. Moreover, increased quagga mussel density and biomass with depth offset the lower benthos density and biomass at deeper depths, and samples with dreissenids had high densities of oligochaetes in both nearshore and offshore communities. These patterns are consistent with facilitative effects of quagga mussels on both shallow and deep-water benthic communities.

The fauna of aquatic invertebrates in the river impacted by wastewaters from the pulp and paper industry (Komi Republic).

BackgroundInvertebrates are important elements of aquatic ecosystems and play a crucial role in the transformation of matter and energy in continental water bodies. Communities of aquatic invertebrates are characterised by high sensitivity to pollution by nutrients and toxic substances and acidification of water bodies; they serve as good bioindicators of the quality of the aquatic environment and impacts on hydroecosystems. All hydrobionts participate in the processes of self-purification of water bodies.The presented dataset provides information on the aquatic invertebrate community of a large northern river. During 2018-2020, we collected data on changes in the quantitative indicators of the development of benthic and planktonic communities, as well as the species diversity of their fauna. The dataset combines information about the occurrence and abundance of benthic and planktonic invertebrates and summarises data of aquatic invertebrate species found in the Vychegda River in the zone of influence from the pulp and paper mill.New informationThe presented dataset is part of a monitoring programme of the river ecosystems in the production area of Mondi Syktyvkar JSC (the European North-East of Russia, Komi Republic). The dataset describes the structure of benthic invertebrate and plankton communities in the Northern Dvina River Basin. The data on the finding and abundance of large taxa of aquatic invertebrates and species of some groups: Oligochaeta, Cladocera, Copepoda, Rotifera, Ephemeroptera, Plecoptera and Trichoptera are presented. In total, the resource includes 8720 findings of invertebrates, of which 6041 are for zoobenthos organisms and 2679 for zooplankton organisms.

COMPARATIVE DATA ON MACROZOOBENTHOS COMMUNITY BETWEEN EASTERN AND WESTERN COASTS OF SAZANI ISLAND, ALBANIA

This paper is focused on analysing the difference in distribution, composition and abundance of benthic invertebrates' populations of the rocky coast of Sazan Island (south western Albania), between its eastern and western sides. This study was carried out during 2012-2014, sampling in shallow water. A total of 56 species of benthic macroinvertebrates were recorded. Species composition and their abundance were compared between the four sampling sites and between the two sampling seasons, spring and autumn. Degree of coast exposure and level of environmental impacts seem to be the main factors regarding the difference in species composition and quantitative characteristics of macrozoobenthic community between the eastern and western coasts of the island.

Effects of aquaculture waste feeds and antibiotics on marine benthic ecosystems in the Mediterranean Sea

Intensive aquaculture is an important source of organic waste and antibiotics into the marine environment. Yet, their impacts on benthic marine ecosystems are poorly understood. Here, we investigated the ecological impacts of fish feed waste alone and in combination with three different antibiotics (i.e., oxytetracycline, florfenicol and flumequine) in benthic ecosystems of the Mediterranean Sea by performing a field experiment. We assessed the fate of the antibiotics in the sediment and their accumulation in wild fauna after two weeks of exposure. Moreover, we investigated the impact of the feed waste alone and in combination with the antibiotics on sediment physico-chemical properties, on benthic invertebrates, as well as on the microbiota and resistome of the sampled sediments. One week after the last antibiotic application, average oxytetracycline and flumequine concentrations in the sediment were <1% and 15% of the applied dose, respectively, while florfenicol was not detected. Flumequine concentrations in wild invertebrates reached 3 μg g−1, while concentrations of oxytetracycline were about an order of magnitude lower, and florfenicol was not detected. Feed waste, with and without antibiotics, increased the concentration of fine particulate matter, affected the pH and redox conditions, and significantly reduced the biodiversity and abundance of benthic invertebrates. Feed waste also had a significant influence on the structure of sediment microbial communities, while specific effects related to the different antibiotics ranged from insignificant to mild. The presence of antibiotics significantly influenced the normalized abundance of the measured antibiotic resistance genes. Florfenicol and oxytetracycline contributed to an increase of genes conferring resistance to macrolides, tetracyclines, aminoglycosides and chloramphenicol, while flumequine had a less clear impact on the sediment resistome. This study demonstrates that feed waste from aquaculture farms can rapidly alter the habitat and biodiversity of Mediterranean benthic ecosystems, while antibiotic residual concentrations can contribute to the enrichment of bacterial genes resistant to antibiotic classes that are of high relevance for human medicine.

The physical–chemical environment and benthic invertebrate assemblages of two thermal springs located on carbonate and ophiolite rocks in northern Oman

ABSTRACT The paper compares the physical and chemical environments and associated benthic invertebrate assemblages of two thermal streams with different geology in Oman. Nakhal Thawarah is a thermal spring originating in carbonate rocks. Mur-Fayha has its origin in igneous ophiolite rocks. The main physical and chemical parameters that contribute to the differences are water temperature, pH, electrical conductivity, total dissolved solids, chloride, sulphate, calcium and magnesium. Two zones in each spring-stream system, the source and stretch analysed, reveal intra- and interstream differences in the physical and chemical environments controlling the occurrence and abundance of benthic invertebrates. Despite higher water temperatures, the diversity of benthic invertebrates in Nakhal Thawarah is relatively high. Mur-Fayha with high alkalinity is a harsh environment that has low diversity dominated by tolerant Chironomidae. This study indicates the need to conserve thermal springs in Oman from adverse effects of tourism.

Anthropogenic Impact on Plankton and Benthos Assemblage in the Lagos Lagoon, Nigeria

Abstract The physico-chemical parameters, plankton and macro-benthic invertebrates of the Lagos Lagoon (Badore, Ajah), Lagos State, Nigeria were studied between February and July 2018 at four sampling stations in a disparate range of human activities and impact. The result of phytoplankton analysis indicated a total of 56 genera with 40 genera within Bacillariophyta, accounting for 72% of the abundance. Zooplankton comprised 26 genera with 82% of the abundance of crustacea. The benthic macroinvertebrates were composed of mollusca, arthropoda and annelida. Results also indicated that the main drivers affecting the abundance and distribution of planktonic and benthic invertebrates were water temperature, pH, TDS and EC. The monthly variations of physico-chemical parameters in the Lagoon could be the result of human activities associated with transportation, fishing and domestic sewage disposal from the surrounding settlements. Therefore, it is necessary that relevant authorities keep in check some of these activities around the Lagoon as well as educate the population on the necessity for the conservation of these water resources.

Environment and Space Rule, but Time Also Matters for the Organization of Tropical Pond Metacommunities

Metacommunities are dynamic systems, but the influence of time independently of environmental change in their configuration has been rarely considered. Temporary ponds are excellent ecosystem models, as they have well-defined boundaries in time and space; their communities are relatively isolated through a landscape matrix, and the progress of time leads to major changes through ecological succession and in habitat suitability related to hydroperiod dynamics. Therefore, strong temporal effects are expected to influence their metacommunity structure. We surveyed 30 temporary ponds along the dry tropical region of western Costa Rica and Nicaragua at three different moments of their hydroperiod: shortly after the infilling of the water bodies, at the middle of the hydroperiod and just before desiccation. We obtained data on 56 environmental variables (including limnological, climatic, landscape, hydrogeomorphological and conservation state), and used geographic coordinates to build spatial variables (Moran Eigenvector Maps). We collected biological samples and estimated the specific abundance of phytoplankton, zooplankton and benthic invertebrates. To evaluate the relative role of environmental, spatial and temporal (sequential sampling season) effects in metacommunity organization of the 646 species found, we used variation partitioning with distance-based redundancy analyses for each group of organisms. We repeated the analyses for selected taxonomic groups, separately for each sampling season, to check how the variance explained by spatial and environmental factors varied between sampling periods. The inclusion of time in the analysis highlighted that pure temporal effects explained part of metacommunity variance in almost every group, being as important as spatial or even environmental effects for some groups of organisms. In contrast to the assumed low environmental constraints in tropical areas (i.e. high and stable temperatures), we found strong environmental effects. Passive dispersers were more influenced by environmental factors than active ones. We also found a positive relationship between the body size of the different groups of organism and the magnitude of the temporal effect, interpreted as related to generation time. Finally, when analyzing each sampling period separately, we found differences in the relative role of environment and space at different sampling periods, showing that snapshot surveys may not be representative of highly dynamic metacommunities.

Evidence of surplus carrying capacity for benthic invertebrates with the poleward range extension of the tropical seagrass Halophila decipiens in SE Brazil

Seagrasses may enhance the abundance and diversity of benthic invertebrates through trophic facilitation. We investigated this potential ecological function for two seagrasses in SE Brazil: Halodule emarginata, a native species, and Halophila decipiens, a tropical seagrass recently established in the region. At Halophila sites, the organic matter (or carbon) in sediments decreased steadily from seagrass patches to isolated bare grounds, indicating surplus primary production. This was not observed at Halodule sites. At one of the two Halophila sites, localized trophic enrichment was also consistently linked to increased invertebrate abundance within patches, chiefly through increased carrying capacity of small mesoherbivores. Rather than spillover, edge effects were observed at bordering bare habitats, where polychaete predators were abundant. The transition from seagrass edges to isolated bare habitats was marked by an increase of the density of sipunculid worms. The current spread of Halophila may thus change the spatial distribution of benthic ecological functions.

Enhanced biodiversity and abundance of benthic invertebrate macrofauna in a New Zealand marine reserve

Abstract No‐take marine reserves are an important management tool in the conservation and restoration of marine habitats around the world. They are intended to provide spatial refugia for exploited species and to protect sensitive habitat and biodiversity hot spots. Despite strong evidence that marine reserves enhance overall biodiversity, it is not clear that this effect extends to all taxonomic groups. Most marine reserves are designed to protect large mobile fauna. Their effect on small sessile benthic invertebrates is unclear, yet these organisms provide critical ecosystem functions. Three hundred and seventy‐eight images and associated faunal descriptions were compared from 2007 and 2018 in Ulva Island/Te Wharawhara Marine Reserve, Stewart Island/Rakiura, New Zealand (46.9°S, 168.1°E, 0–25 m depth, established 2004), to discern the effect of non‐extractive marine protection on a soft‐sediment temperate benthic community. Qualitative habitat types observed in the 2018 images were similar to those described in 2007. There was a significant positive effect of protection on benthic invertebrate abundance between 2007 and 2018 across Paterson Inlet/Whaka a Te Wera. Additionally, there were significantly more benthic invertebrates within reserve sites compared with sites outside the reserve in 2018. Based on these positive effects, it can be concluded that Ulva Island/Te Wharawhara Marine Reserve has facilitated an increase in the biodiversity of the benthic invertebrate community of Paterson Inlet/Whaka a Te Wera, Stewart Island/Rakiura. Interestingly, heavily calcified biogenic reefs were present within Paterson Inlet/Whaka a Te Wera, but not within the reserve itself. The re‐evaluation of marine reserve boundaries could result in more comprehensive and representative management of the rich marine environment around Stewart Island/Rakiura.

Megalopae of the invasive crab Hemigrapsus sanguineus metamorphose in response to marine biofilms from different potential habitats

Habitat characteristics favoring settlement and metamorphosis of larvae can affect the distribution and abundance of benthic marine invertebrates. Less selective responses to habitat cues by settling larvae can lead to broader distributions of species and potentially successful introduction to new geographic locations. This study tested whether marine biofilms, which serve as habitat cues for many invertebrates, enhance settlement and metamorphosis (molting) of megalopae of the invasive Asian shore crab Hemigrapsus sanguineus. Biofilms were allowed to develop on plastic mesh netting deployed in coastal locations with abundant rocky substrate (adult habitat) and estuarine locations with few rocks. Molting rates of laboratory-reared megalopae maintained with biofilm-covered netting were determined. Controls consisted of mesh netting without field-derived biofilms and seawater without netting. Experiments were also conducted with megalopae of a native species of estuarine mud crab, Dyspanopeus sayi, for comparison of responses. Both species molted faster in response to field biofilms regardless of habitat of biofilm development, although the response to biofilms compared to netting without biofilms was stronger for H. sanguineus than D. sayi. The broad response of megalopae of both species to biofilms suggests that positive responses to biofilms and physical structure could be important for successful colonization of crab species in general.

Echinoderms of the Kuril-Kamchatka Trench

Echinoderms collected in the Kuril-Kamchatka Trench (KKT) at depths greater than 6000 m by expeditions onboard RV Vityaz and Sonne (KuramBio II) are listed, with some taxonomic and biogeographic remarks. The echinoderm fauna of the KKT (>6000 m) includes 44 species, of which 29 were determined to the species level and 15 to the generic level; 14 species and 6 genera (Echinosigra, Gephyrothuria, Mesothuria, Molpadia, Molpadiodemas and Sonnetrochus) were recorded for the KKT for the first time. The KKT echinoderm fauna mainly comprises species (86%) from the cosmopolitan genera. Of the 29 identified species, 11 (38%) are endemics of the hadal zone, including 6 (21%) endemics of the KKT. Species of holothurians make up more than half of all known echinoderm species in the KKT. The number of echinoderm species at depths 6000–7000 m is 29, which decreases sharply to 16 at depths 7001–8000 m, stabilizes at 17 at depths 8001–9000 m and further declines to 8 from 9001 to 10,000 m. The proportion of holothurians increases with depth from 48% to 87%. The number of species in the KKT echinoderm fauna is much greater than in any other trench. The second–highest echinoderm species richness (19 species) is known from the South Sandwich Trench. Both trenches are located in areas of high primary productivity and are characterized by a high abundance of benthic invertebrates in trawl catches.

Lower diversity of recruits in coastal reef assemblages are associated with higher sea temperatures in the tropical South Atlantic

Climate change will lead to community shifts and increase the vulnerability of coastal marine ecosystems, but there is yet insufficient detail of how early life stages of marine populations are linked to oceanic-climate dynamics. This study aimed to investigate how ocean-climate variability is associated with spatial and temporal changes in benthic larval recruitment of tropical reef assemblages. Recruitment (abundance, richness, and diversity) of benthic invertebrates was monitored for one year on macroalgal beds in four rocky reefs in a marine protected region in the Eastern coast of Brazil, and compared to fluctuations in meteo-oceanographic conditions at multiple temporal scales (days, weeks, and months). Our results revealed that recruitment of benthic invertebrates varies widely (up to 15 orders of magnitude) among sampled reefs and in time, with wave height, wind speed, and sea temperature being significantly related to recruitment variability. We detected strong taxonomic variability in recruitment success and ocean-climate variables, which highlights the complexity of estimating community vulnerability to climate change in benthic communities. Given that macroalgal beds are key to recruitment of some species regionally (4–30 km), the protection of coastal nursery habitats may be critical for marine conservation and species adaptation in a climate change scenario. Considering the projected ocean-climate change in IPCC scenarios, our study suggests that recruitment of marine populations in coastal reefs could be highly sensitive to climate change in the tropical South Atlantic Ocean.