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Anthropogenic and environmental stressors damage the structure and function of coral reefs. Monitoring data is important because it allows scientists to detect changes that are of interest for managers and policymakers. This study aims to examine the benthic component (abiotic and biotic) and determine coral life-history composition at different reef types (atoll and fringing) and regions (Wangi-Wangi and Kaledupa) in the Wakatobi National Park (WNP), Southeast Sulawesi, Indonesia. We examine the data using life-history traits in regard to group species and describe community composition. Kaledupa fringing reef had 46% hard coral cover, which was the highest hard coral cover in our study. There was no significant difference in hard coral and soft coral cover between regions within WNP. Reef type, however, showed significant differences in hard coral and soft coral cover, as well as sand, rubble, and rock. The families Acroporidae and Poritidae were the most dominant across all sites and reef types in WNP. The life-history classification showed competitive and stress-tolerant coral covers were greatest on fringing reefs. Our findings provide information regarding coral reef benthic community composition and distribution across regions and reef types in WNP, which can aid in coral reef conservation. [ABSTRACT FROM AUTHOR]

Streams constitute the water supply of the watersheds and provide the transfer of energy along the course of water, ensuring water biodiversity. Due to the different uses of the earth, the benthic community is being suppressed. The objective of this study is to investigate the effects of changes in land use on the abundance, richness, and diversity of benthic macroinvertebrates in subtropical streams, considering the physical and chemical variables of streams seasonally. In total, 144 samples were collected between February 2022 and November 2023 at 12 sites distributed in a watershed in southern Brazil, four sites for each land use. Herein, 83.520 individuals were identified, comprising 67 taxa. There was a decrease in richness along the forested–rural–urban gradient and a greater abundance in the urban environment, without the significant influence of seasonality. We conclude that the diversity of benthic macroinvertebrate in the streams is influenced not only by environmental variables but also by the spatial distribution between streams. The proximity of the streams generates a similarity in dominance. This study contributed to understanding the relationships of the environment with the benthic community and considering the spatial distribution among the streams sampled in future investigations. [ABSTRACT FROM AUTHOR]

Dokdo Island's diverse marine ecosystem requires long-term monitoring to understand the effects of rapid environmental changes, such as global warming, on macrobenthos species and communities. Current studies are often short-term and limited, highlighting the need for extended research to predict future changes to ecosystems. This study analyzed the environmental variables influencing macrobenthos through long-term monitoring. In total, 511 species (spp./23.4 m2) were identified with an abundance of 1709.9 individuals/m2 and a diversity of 2.9. Since 2020, there has been a decline in both the number of species and diversity, attributed to changes in sediment composition, particularly an increase in gravel and sand. The dominant species include the crustacean Abludomelita denticulata (17.6%), the polychaete Haplosyllis spongiphila (6.8%), the bivalve Glycymeris munda (5.6%), the polychaete Opisthodonta uraga (5.3%), and the bivalve Limatula japonica (3.8%). The macrobenthos community differs each year, as the dominant species G. munda has decreased in abundance since 2022 and L. japonica since 2021. Depth and gravel sediment strongly correlated with community variation. Site-specific analysis also showed significant differences, with depth, bottom temperature, and sediment composition as the influencing factors. These species thrive in cold water but their abundance declines with an increase in temperature. Continuous long-term monitoring is essential to understand and protect the Dokdo ecosystem amid rapid environmental changes. Long-term monitoring studies have revealed more species than have short-term studies, showing annual and site-specific environmental changes, including sediment erosion and bottom temperature increases. These changes have affected macrobenthos diversity, abundance, and community composition, necessitating ongoing research to determine the persistence of these trends and to protect the ecosystem. [ABSTRACT FROM AUTHOR]

Accurate assessments of ecosystem condition are needed to inform management processes such as systematic conservation planning and protected area expansion, marine spatial planning and other effective area‐based conservation measures. Yet measuring the condition of dynamic and often largely inaccessible marine ecosystems is extremely difficult and presents a global challenge.Broad‐scale cumulative impact assessments have been used in South Africa as a proxy for marine ecosystem condition in national assessments and reporting because the data are more readily available, and knowledge exists on the impacts of various human activities (or pressures) on marine ecosystems. While useful for national reporting, assessments based on in situ ecological data are also needed at finer scales relevant to management.Applying the HELCOM BEAT approach, this study used in situ ecological data to identify potential methods and indicators that can be applied in South Africa to conduct integrated ecosystem assessments and to assess the suitability of current cumulative impact assessments as a proxy for condition.Aggregated fish indicators demonstrated greater sensitivity to varying human pressures compared with benthic community indicators, with responsiveness differing by location. Notably, site‐level differences in empirical condition emerged that broad‐scale cumulative assessments often missed. The study thus highlighted the varying suitability of cumulative impact scores as proxies for condition, indicating their reliability for fish communities. However, this is also dependent on the pressure types included, the biotic indicators used and the area of focus.Conservation decisions based solely on cumulative impact scores could misrepresent the actual condition of the environment, which makes it difficult to make management decisions, especially at finer scales. As such, conservation initiatives need to be regionally adapted to effectively address the unique pressures and conditions of each area and should be tailored to account for fine‐scale variability, instead of adopting a one‐size‐fits‐all approach. [ABSTRACT FROM AUTHOR]

Resident salt marsh fishes consume a diversity of intertidal benthic prey whose abundances may be affected by anthropogenic stressors. A generalist feeding strategy in which diet closely matches the benthic community could allow these fishes to flexibly track changes in prey availability, whereas selection for particular prey may put these fishes at risk if preferred resources decline, especially as warming water temperatures increase metabolic demand. This study detected differences between the diet of adult mummichogs (Fundulus heteroclitus) and the benthic prey community at salt marshes along Hoffler Creek in southeastern Virginia, USA, in May through August of 2 years. Polychaetes made up 74.8% of benthic samples but were only 33.9% of benthic prey items identified in diet samples. Compared to benthic samples, mummichog diet contained higher percentages of small arthropods, including ostracods, copepods, amphipods, and Diptera larvae, with substantial variation across months and sites. Consumption of large numbers of arthropods by some individual fish suggests they were taking advantage of patchily abundant prey. Despite these differences, mummichog diet reflected major temporal and spatial patterns in the benthos, including increased consumption of polychaetes in late summer and of ostracods at the upstream site in 2017. These results suggest that mummichogs are not uniformly generalist in their diet but that they may still be fairly robust to variation in prey availability due to their ability to consume large numbers of abundant prey on a small spatial scale and to track changes in the most abundant prey categories through time. [ABSTRACT FROM AUTHOR]

Streams constitute the water supply of the watersheds and provide the transfer of energy along the course of water, ensuring water biodiversity. Due to the different uses of the earth, the benthic community is being suppressed. The objective of this study is to investigate the effects of changes in land use on the abundance, richness, and diversity of benthic macroinvertebrates in subtropical streams, considering the physical and chemical variables of streams seasonally. In total, 144 samples were collected between February 2022 and November 2023 at 12 sites distributed in a watershed in southern Brazil, four sites for each land use. Herein, 83.520 individuals were identified, comprising 67 taxa. There was a decrease in richness along the forested–rural–urban gradient and a greater abundance in the urban environment, without the significant influence of seasonality. We conclude that the diversity of benthic macroinvertebrate in the streams is influenced not only by environmental variables but also by the spatial distribution between streams. The proximity of the streams generates a similarity in dominance. This study contributed to understanding the relationships of the environment with the benthic community and considering the spatial distribution among the streams sampled in future investigations.

Dokdo Island’s diverse marine ecosystem requires long-term monitoring to understand the effects of rapid environmental changes, such as global warming, on macrobenthos species and communities. Current studies are often short-term and limited, highlighting the need for extended research to predict future changes to ecosystems. This study analyzed the environmental variables influencing macrobenthos through long-term monitoring. In total, 511 species (spp./23.4 m2) were identified with an abundance of 1709.9 individuals/m2 and a diversity of 2.9. Since 2020, there has been a decline in both the number of species and diversity, attributed to changes in sediment composition, particularly an increase in gravel and sand. The dominant species include the crustacean Abludomelita denticulata (17.6%), the polychaete Haplosyllis spongiphila (6.8%), the bivalve Glycymeris munda (5.6%), the polychaete Opisthodonta uraga (5.3%), and the bivalve Limatula japonica (3.8%). The macrobenthos community differs each year, as the dominant species G. munda has decreased in abundance since 2022 and L. japonica since 2021. Depth and gravel sediment strongly correlated with community variation. Site-specific analysis also showed significant differences, with depth, bottom temperature, and sediment composition as the influencing factors. These species thrive in cold water but their abundance declines with an increase in temperature. Continuous long-term monitoring is essential to understand and protect the Dokdo ecosystem amid rapid environmental changes. Long-term monitoring studies have revealed more species than have short-term studies, showing annual and site-specific environmental changes, including sediment erosion and bottom temperature increases. These changes have affected macrobenthos diversity, abundance, and community composition, necessitating ongoing research to determine the persistence of these trends and to protect the ecosystem.

Coastal marine ecosystems are integral in providing numerous ecosystem functions and services. However, intense and chronic anthropogenic stressors often impact marine ecosystems surrounding highly urbanized, densely populated coastal megacities. The associated reduction of water quality and biodiversity of these ecosystems potentially erodes ecosystem functions and provision of services. While there is general consensus that greater biodiversity supports a multitude of ecosystem functions, evidence from marine ecosystems in real-world settings is lacking. In this study, we evaluated the influence of water quality on benthic and fish assemblages, as well as quantified six key ecosystem functions in coastal waters of Hong Kong. Hong Kong’s marine ecosystems are marred with long-term damage that is directly linked with rapid economic growth and anthropogenic activities. We found that water quality significantly affected community composition and clustered assemblages into separate groups related to strength of impact: high impact sites were generally dominated by bivalves and small, opportunistic organisms such as damselfish (Pomacentrinae) and cardinalfish (Apogonidae); low impact sites were dominated by macroalgae, bryozoa, and commercially important piscivores such as groupers (Epinephelinae) and seabreams (Sparidae). Ecosystem function tests showed that low impact sites were much more productive than high impact sites, with 15-times greater macroalgal cover and 5-times higher fish biomass. On the other hand, herbivory and predation rates were context-dependent due to underlying biodiversity effects such as selection, complementarity, and competition. Eutrophication increased decomposition and reduced carbon sequestration, but excessive nutrient input could have suppressed decomposer activities via hypoxia. Therefore, we show that in high impact sites where top-down control is removed, resilient and opportunistic organisms such as cardinalfishes and sea urchins may expand to fulfill functional roles, effectively maintaining ecosystem functions such as predation and herbivory in degraded habitats. Contrary to general consensus, this study demonstrates the merit in conserving even highly impacted marine habitats due to their persistent ecosystem functionality despite chronic water quality issues and shifts in benthic and fish assemblages.

Bioassessment of complex and heterogeneous ecosystems is a challenge when there are multiple, strong, natural environmental gradients; unknown, or spatially varying, mixtures of stressors; and large numbers of taxa with unknown responses to both the environmental gradients and the stressors. Current methods of bioassessment are not designed for use under this set of constraints. To address this gap, we have developed an assessment method appropriate for well-sampled, heterogeneous systems with many taxa. In the bioassessment described below, we model taxa occurrence as a function of natural environmental gradients, then use residual covariance patterns between all pairs of taxa to estimate the impact of human disturbance across sites as a latent construct. The derivation of the method from an underlying causal model allows the metric value at each site and the associated taxa responses to be partitioned into contributions from a set of putative stressors. We apply this method as a case study to the subtidal benthic invertebrate community of Puget Sound, WA (USA) and demonstrate a partial decomposition of the metric values to a set of stressors including sediment organic carbon, nitrogen, metals, and organic pollutants. While this method provides new opportunities to estimate, communicate, and understand the ecological condition of complex, heterogeneous ecosystems, due to the requirement for broad, detailed data to inform its estimates, it will likely be most appropriate for monitoring programs.

The purpose of this study was to analyze changes in the assemblage of benthic macroinvertebrates, as a response to anthropogenic environmental alterations in a river of the Extra-Andean Patagonia. Four sampling surveys were carried out between March 2017 and March 2019, in contrasting seasons on the middle course of the Chico River (Santa Cruz). Six sampling stations were established: two reference stations upstream of Gobernador Gregores town and four downstream at increasing distances from the locality. At each station, physic-chemical variables were measured and four macrobenthos samples were collected using a manual Surber-type net with a 500-µm mesh. The abundance of taxa and functional feeding groups (GFA) were analyzed using univariate and multivariate statistical methods. Twenty-six taxa were identified; the best represented were oligochaetes, hirudineans, gastropods and Chironomidae, Baetidae and Glossosomatidae insects. The reference stations and those further from the town presented higher values of diversity and richness of taxa and GFA; Chilinidae and Lymnaeidae molluscs were more important together with Baetidae, Glossosomatidae and Gripopterygidae insects. At the downstream stations, closer to the town, Naididae oligochaetes and Chironomidae insects dominated the macroinvertebrate assemblage with lower values of diversity and richness of taxa and GFA. The collectors-gatherers were the dominant feeding groups in these stations, where the contribution of urban effluents favored the detrituseating pathway and the opportunistic feeding strategy. Changes in composition and trophic structure of the macroinvertebrate assemblage provide relevant information to understand ecological modifications due to environmental alteration, and are of fundamental importance to interpret the biotic indices used to evaluate water body quality. [ABSTRACT FROM AUTHOR]

Coral reef decline is an issue of concern around the globe. Remote and uninhabited coral areas are not exempt from facing changes in species composition and functionality due to global drivers. Quitasueño is a remote atoll within the Seaflower Biosphere Reserve, in the Southwestern Caribbean Sea. To evaluate the current status of the coral reefs in Quitasueño we sampled 120 stations through Rapid Ecological Assessment and evaluated four stations through Planar Point Intercept to compare the current percent cover of benthic groups with previous studies in the area. We found pronounced changes in coral and macroalgae covers in time, and great conspicuousness of multiple conditions of deterioration along Quitasueño, including diseases, coral predation, and aggression and invasion of coral colonies by macroalgae and sponges. The reef ecosystem seems to be facing a phase shift, in which the benthic cover previously dominated by hard corals is currently dominated by fleshy macroalgae. It is essential to evaluate the possible drivers of the extent of degradation of Quitasueño to understand the process of deterioration and mitigate the impacts. [ABSTRACT FROM AUTHOR]

The shallow-water hydrothermal system of Punta Mita in Banderas Bay is located on the fault called Fisura de las Coronas off Punta Pantoque beach. In this area, three sites with hydrothermal vents were studied at a depth of 9 m. This study aimed to characterize the structure of the benthic infauna communities that coexist in this hydrothermal system; therefore, physicochemical parameters were measured and the organisms found in the sediment samples were identified up to the class taxonomic level. The highest temperatures (89°C) were recorded within the hydrothermal influence area, which was reflected in an inverse relationship with pH, conductivity and salinity. Sediment temperature profiles increased at greater depth. A total of 371 individuals were found and these were grouped into eight classes: Malacostraca, Maxillopoda, Gastropoda, Bivalvia, Scaphopoda, Polychaeta, Leptocardii and Stenolaemata. The Malacostraca class was the most abundant with 240 individuals, while the Scaphopoda was the lowest with 3. The organic matter contents in the sediments were higher in the areas adjacent to the hydrothermal activity. The high temperature of the hydrothermal discharges structures the benthic community since it was the factor that differed most significantly in the study sites, causing lower abundances in the area of hydrothermal influence compared with the more distant areas. Despite the above, it is concluded that the benthic community of the area with hydrothermal activity is part of the community adjacent to this influence, only in lower numbers. [ABSTRACT FROM AUTHOR]

Sediment density flows are large scale disturbances that can have dramatic impacts on seafloor animal communities in the deep sea. Seafloor imagery collected in Kaikōura Canyon (New Zealand), before and after a sediment density flow event that included debris and turbidity flows triggered by a 2016 Mw 7.8 Kaikōura Earthquake, shows the recovery trajectory of the animal community in the canyon head in the weeks, months, and years following the disturbance. The canyon community appears resilient to this event, with models estimating full recovery within a minimum of 4.5–5.1 years and as long as 12 years. The implications of the resilience of this deep-sea community are discussed in the context of the local marine protected area, the surrounding fishery, and global seabed mining.

Coral reef decline is an issue of concern around the globe. Remote and uninhabited coral areas are not exempt from facing changes in species composition and functionality due to global drivers. Quitasueño is a remote atoll within the Seaflower Biosphere Reserve, in the Southwestern Caribbean Sea. To evaluate the current status of the coral reefs in Quitasueño we sampled 120 stations through Rapid Ecological Assessment and evaluated four stations through Planar Point Intercept to compare the current percent cover of benthic groups with previous studies in the area. We found pronounced changes in coral and macroalgae covers in time, and great conspicuousness of multiple conditions of deterioration along Quitasueño, including diseases, coral predation, and aggression and invasion of coral colonies by macroalgae and sponges. The reef ecosystem seems to be facing a phase shift, in which the benthic cover previously dominated by hard corals is currently dominated by fleshy macroalgae. It is essential to evaluate the possible drivers of the extent of degradation of Quitasueño to understand the process of deterioration and mitigate the impacts.

The Salar de Olaroz, located in the Argentine Puna, is one of the largest lithium deposits of the world. Lithium extraction requires large amounts of fresh and brackish water, creating pressure on wetlands of these desert environments. The knowledge of the aquatic fauna of the area is of interest to monitor impacts of these extractive activities. In this work, a study of the Chironomidae (Diptera) prior to mining is carried out in order to understand the structure of the Chironomidae assemblage at morphospecies level, with the aim of evaluating its spatial and seasonal variation, relating changes in the assemblage to some environmental variables. Quantitative biological samples and environmental variables of interest were taken and registered in three streams during four season in three consecutive years (2013-2015). Our results show that the Chironomidae assemblage could respond to variables related with discharge by decreasing its richness. Some morphotypes (e.g., Podonomus, Parametriocnemus, Limnophyes and Polypedilum) associated with changes in pH, decreases in dissolved oxygen and water velocity, and increases of finer sediments could disappear from the area. [ABSTRACT FROM AUTHOR]

Acute disturbances and chronic pressures have an important and increasing influence on the structure of coral reef communities. For the viability of benthic taxa such as stony corals, a balance between loss following disturbance and recovery is vital. Coral populations on reefs with lower exposure to chronic pressures are often presumed to have increased resilience, enabling them to recover quickly following disturbance, but decades of anthropogenic stress and degradation may undermine the systematic recovery and reassembly of benthic communities. This study explored spatiotemporal changes in benthic community structure over a 15 yr period at three distinct coral reef regions with a gradient of chronic pressures in Florida, USA, (southeast Florida, the Florida Keys and the Dry Tortugas). We specifically assessed the spatial scale, potential drivers of change and resilience in stony coral, octocoral, sponge and macroalgae cover. Spatiotemporal changes were assessed at four different scales: among regions, habitats, sub-regions, and habitat types within regions. Cover of stony corals remained very low or declined in every region from 2004 to 2018, with corresponding increases in macroalgae cover. Stony coral recovery was limited regardless of regional differences in chronic pressure. Octocorals exhibited greater resilience due to increased recovery following disturbance and generally had higher cover than stony corals on Florida's Coral Reef, while sponge cover was very stable over the study period. Acute disturbances, which affected sites on average once every 3 yr, negatively impacted stony coral and/or octocoral cover in every region and habitat, contributing to the regionwide proliferation of macroalgae. This study determined that high disturbance frequency and chronic anthropogenic pressures on Florida's Coral Reef have led to sustained declines in stony corals and corresponding proliferation of macroalgae. Stony corals were expected to recover during inter-disturbance periods, but in Florida, even in locations with lower chronic pressure, recovery is severely limited. [ABSTRACT FROM AUTHOR]

Context: Although increases in macroalgal cover on coral reefs are often reported alongside declines in coral, the composition of algal assemblages and their spatial dynamics are not commonly investigated. Aims: To quantify changes in macroalgal assemblage composition over two spatial environmental gradients, depth and distance from shore, within a nearshore reef system in Kimbe Bay, Papua New Guinea, where coral cover has declined. Methods: Benthic cover was quantified at three depths (reef flat, 10 and 15 m) on the windward reef slopes of six reefs located three distances from shore (fringing reefs, and platform reefs 100–200 m and 0.7−1 km offshore). Key results: Macroalgal cover was highest on the reef flat, and assemblage composition varied among depths and distances from shore. Macroalgal cover was not correlated with coral cover except where macroalgal cover was greater than 20%, where a negative correlation occurred. There was no correlation between macroalgal cover and turf algal cover. All three benthic groups were negatively correlated with the combined total cover of sand and gravel. Conclusions: These results indicated a fine-scale spatial structure of macroalgal assemblages on coral reefs over a narrow depth range and short distance from shore and highlighted the importance of a solid substratum. Implications: It is likely that the ecological interactions between corals and macroalgae vary considerably over narrow spatial gradients. It is becoming increasingly important to understand coral reef macroalgal assemblages as they continue to rise in abundance globally. Here we surveyed near-shore coral reefs in Kimbe Bay, PNG, to characterise macroalgal assemblage changes with depth and fine-scale distance from shore. We found that the assemblage differed with depth and within an offshore distance of less than 1 km, and total cover was highest at shallow depths. [ABSTRACT FROM AUTHOR]

Offshore wind infrastructure modifies benthic habitats, affecting ecosystem services. A natural capital approach allows risks to nature-based assets and ecosystem benefits to be assessed. The UK Natural Capital Committee produced guidance for conducting natural capital assessments to aid decision making processes. Development of an asset register and risk register are key components of this methodology. The former provides an inventory of NC stocks, and the latter considers the likelihood of changes and the scale of their impact on delivery of ecosystem services. In this study, suitability of the methodology in a marine environment context was critically evaluated. Natural capital stocks before and after installation of Greater Gabbard offshore wind farm were compared and risks to delivery of ecosystem services were assessed. It was demonstrated that incorporating an assessment of impacts on natural capital assets in planning and management decisions (as an extension to traditional environmental impact assessment approaches) could further facilitate sustainable use of marine ecosystems. For example, by preventing access to bottom-trawl fisheries activities, wind farms may promote recovery and increase value of seabed natural capital assets. By also introducing aquaculture systems loss of food provision (from reduced fishing activity) could be offset whilst allowing benthic natural capital assets to recover. Natural capital assessment is relevant to the marine context. However, application of the Natural Capital Committee's methodology was constrained by the limited coverage of standard benthic sampling tools. Given the scale of wind energy plans across the marine environment it is recommended that these shortcomings are appropriately addressed. • Offshore wind structures may alter benthic natural capital and positively and negatively affect ecosystem services. • A natural capital approach provides a means to assess risks to natural capital-ecosystem service relationships. • Limitations in sampling methodology constrained development of a natural capital asset register and asset risk register. • Evidence from similar habitats was not sufficient to be applied as proxies. • Risks to natural capital-ecosystem service relationships could be reasonably estimated to inform management options. [ABSTRACT FROM AUTHOR]

The Salar de Olaroz, located in the Argentine Puna, is one of the largest lithium deposits of the world. Lithium extraction requires large amounts of fresh and brackish water, creating pressure on wetlands of these desert environments. The knowledge of the aquatic fauna of the area is of interest to monitor impacts of these extractive activities. In this work, a study of the Chironomidae (Diptera) prior to mining is carried out in order to understand the structure of the Chironomidae assemblage at morphospecies level, with the aim of evaluating its spatial and seasonal variation, relating changes in the assemblage to some environmental variables. Quantitative biological samples and environmental variables of interest were taken and registered in three streams during four season in three consecutive years (2013-2015). Our results show that the Chironomidae assemblage could respond to variables related with discharge by decreasing its richness. Some morphotypes (e.g., Podonomus, Parametriocnemus, Limnophyes and Polypedilum) associated with changes in pH, decreases in dissolved oxygen and water velocity, and increases of finer sediments could disappear from the area.

Bottom trawling has widespread impact on the structure and composition of benthic communities. In this study, soft-bottom macrofauna in a heavily trawled area and an adjacent marine park that has been closed to bottom trawling for more than ten years were sampled, allowing to investigate the impact of and recovery from trawling. Both areas were equally affected by seasonal summer hypoxia. Polychaetes were the most abundant at trawled (78-86%) and non-trawled (85-94%) sites in both summer and winter. The non-trawled sites inside the marine park area had a lower level of species composition and abundance as compared to the trawled sites in summer, whereas in winter the benthic communities at these trawled and non-trawled sites appeared much similar with the majority of the identified taxa being dominated by new recruiting juveniles in both sampling areas. Results of permutational multivariate analysis of variance (PERMANOVA) on transformed infaunal abundance and biomass data revealed significant differences (p

Aim: Reef fishes are commonly recognized as sentinels of the ongoing tropicalization in biogeographic transition zones between temperate and tropical areas. Despite the reliance of these marine ectotherms on the benthos, the importance of benthic habitat has rarely been considered as a factor constraining fish distribution. Therefore, our study aims at examining the consequences of both temperature and benthic variations on the fish fauna and diagnosing potential sentinels of these environmental changes. Location: Taiwan, West Pacific. Taxon: Teleostei (184 species). Methods: We examined how the partitioning of habitats can influence the specialization of fish fauna along a latitudinal gradient. We diagnosed 'specialist' and 'generalist' fishes in this partitioning. For each specialist, we further evaluated whether its distribution is constrained by temperature, benthic habitat or both factors combined. The change in sea surface temperature over the last three decades was also monitored. Results: Fish fauna showed the highest specialization when tropical and subtropical partitions of habitat were considered. Fifty‐one tropical specialists, 7 subtropical specialists and 21 possible generalists were identified. Among specialists, 13 species were associated with temperature, 19 with habitat and 26 with both factors. Steady warming occurred across latitudes, but was accentuated in the winter of subtropical habitat. Main Conclusions: Our results suggested that the distribution of some specialist fishes was constrained only by temperature while the distribution of some others also depended on the availability of benthic habitats. Consequently, under global warming, the distribution of some specialists might shift in a manner that follows the movement of isotherms, while the distribution of others might also be conditioned by the poleward shifts of benthos. A temporal mismatch between the emergence of suitable thermal environments and the arrival of some specialists may exist. Therefore, the tropicalization of high‐latitude areas may be characterized by different waves of colonization. [ABSTRACT FROM AUTHOR]

Seamounts and oceanic islands play an important role as biodiversity hotspots amid the vastness of the oligotrophic open ocean. While island ecology and evolution have received a lot of attention in the last decades, the exploration and understanding of community and habitat dynamics of seamounts remain challenging. Here, we investigate the ecology and biogeography of fish and benthic communities of a recently discovered southwestern Atlantic reef system at Davis seamount. This seamount belongs to the Vitória-Trindade Chain and is located in international waters off the Brazilian coast. We present this reef system, that also occurs on other shallow seamounts of the chain, as a new reef habitat named "Coralline Hills": Its hill-shaped structure is mainly built by crustose coralline algae and rises up from the seamount summit at 60–70 m to 17 m depth. The benthic community is mainly composed by coralline algae and sponges. Fish biomass at Davis coralline hill is dominated by carnivores, mainly top predators such as nurse sharks and large groupers. The relatively shallow reef top presents higher species richness, abundance and distinct trophic structure (mostly omnivore and planktivore species) than the mesophotic zone (with higher abundance of carnivorous fishes). A biogeographic analysis revealed that the reef fish community structure is greatly influenced by a set of dispersal and establishment traits that strongly differs from that encountered on coastal reefs of the central Brazilian coast and on insular reefs of Trindade Island. Gathering information about the ecology and structure of such unique and remote habitat is timely, since the region is under imminent threat such as fishing and mining and lacks international attention. [ABSTRACT FROM AUTHOR]

The rapid coastal development in the Andaman Islands has resulted in littoral habitat degradation. Understanding the performances of marine biotic indices and the interpretation and translation of those results into coastal health assessment could become an integral tool in future monitoring and management policies. In this line of efforts, the ecological quality status of three sandy beaches, two urban and one nonurban, was evaluated by using three marine biotic indices. The faunal community belonged to moderately well-sorted fine sand biocenosis. The relatively high species richness (15.9 ± 0.80 taxa sample−1) and moderate abundance (563 ± 38.8 ind.m−2) were features of the benthic fauna. The urban beaches (Aberdeen Bay and Carbyn's Cove) corresponded to tolerant benthic communities. Malacoceros indicus, Grandidierella megnae and Scolelepis squamata (tolerant species), and Ampelisca diadema (indifferent species) were the major constituents of urban beaches, while Scoloplos capensis, Urothoe grimaldii, and Urothoe platydactyla (sensitive species) were important at the nonurban beach (Wandoor). The high–good quality status prevailed across the spatial and temporal scales except for Carbyn's cove beach, where good–poor status was noticed. The M-AMBI appeared to be the most robust measure in distinguishing the impact between the urban and nonurban beaches. The constrained ordinations revealed a gradient of disturbance across the beaches. The distinct patterns of sample segregation were the result of the ecological response. This attempt should be considered a comprehensive measure of quality assessment of beaches under human pressure and draw a parallel line of evidence to global studies on sandy beaches. [ABSTRACT FROM AUTHOR]

The Point Intercept Transect (PIT) method has commonly been used in recent decades for estimating the status of coral reef benthic communities. It is a simple method that is efficiently performed underwater, as benthic components are recorded only as presence or absence at specific interval points along transects. Therefore, PIT is also popular in citizen science activities such as Reef Check programs. Longer intervals are commonly associated with longer transects, yet sampling interval length can significantly influence benthic coverage calculations. Despite this, the relative accuracy of longer or shorter intervals related to transect length has not been tested for PIT. In this study, we tested the optimum intervals of PIT for several commonly used transect lengths using the bootstrap method on empirical data collected on tropical coral reefs and non-reefal coral communities. Our results recommend fine intervals of 10 cm or shorter, depending on the length of the transect, to increase the accuracy of estimating benthic community status on coral reefs. Permanent transects should also be considered in long-term monitoring programs to improve data quality.

Seagrasses are gaining attention thanks to their metabolism and potential major role as carbon sinks, with further implications as nature-based solutions against climate change. Despite their recognized importance and the growing number of studies published, there is still a striking paucity of information on seagrass metabolism and contribution to biogeochemical cycles for some seagrass species and ocean areas. In this study we assessed the metabolic balance and nutrient cycling contribution of seagrasses to the benthic compartment of a tropical reef lagoon in Reunion Island, providing original information on a barely studied seagrass species (Syringodium isoetifolium) and a poorly studied ocean region (West Indian Ocean). We measured the net productivity, respiration and the metabolic balance in different components of the lagoon benthic compartment (i.e. seagrass, sediment, and benthic community) and the water-sediment nutrient benthic fluxes at differently impacted sites within the lagoon. The biogeochemical environmental variability, including inorganic and organic indicators of anthropogenic contamination, was also assessed at each site.Large spatial variability was detected in the metabolic balance of each benthic component assessed, also associated with the natural and/or anthropic-driven environmental variability found in the lagoon. The seagrass S. isoetifolium was net autotrophic across the lagoon and contributed to the lagoon benthic metabolism with net plant productivity exceeding by one order of magnitude the plant respiration. The lowest seagrass metabolism was detected at the impacted site. The metabolic balance of the sediment was heterotrophic but the high productivity of S. isoetifolium contributed to reducing the heterotrophy of the whole benthic community. The lagoon-wide benthic metabolic balance was slightly heterotrophic, but the associated uncertainty ranged from autotrophy to heterotrophy. Nutrient concentrations in the lagoon were low and the benthic community capacity for nutrient retention (uptake) and removal (denitrification and anammox) indicated potential for buffering moderate nutrient inputs into the lagoon. Organic contaminants of emerging concern (CECs) were low but detectable in the lagoon, especially in highly frequented beach areas, arising as an environmental quality indicator of interest.

In the face of the complexity and variability of the marine environment, the coastal water quality is seriously polluted by the marine tourism behavior, and the ecosystem structure is degraded, which restricts the sustainable development of the ecological effect of the marine benthic community. Therefore, the impact of the marine tourism behavior on the ecological effect of the marine benthic community in the South China Sea is proposed. Firstly, it constructs the relationship between tourism and ecological environment, and evaluates the impact of marine tourism behavior on the quality of ecological environment, ecosystem and ecological resources. According to the impact and evaluation of marine tourism on eco-environmental quality, the eco-environmental impact of marine economy in the South China Sea is predicted. As the input of neural network, environmental prediction factors set different learning rates for different input parameters, obtain the training model, output RMS error and complete the prediction, and complete the research on the ecological impact of marine tourism and swimming behavior on marine benthic communities in the South China Sea. The results show that whether in summer or winter, marine tourism behavior affects the ecological effect of marine benthic community in the South China Sea. [ABSTRACT FROM AUTHOR]

The Tremiti Islands Archipelago is located in the Central-Southern Adriatic Sea and is characterized by a strong karst activity. Due to their landscape, geological, hydrological, archaeological, and historical value, Tremiti Islands are considered a geomorphosite. We carried out a preliminary, non-destructive survey by studying the speleological and biological features of the submerged sea cave Elle, located at Cala Sorrentino (Capraia Island), representing an EU Natura 2000 Priority Habitat. Topographic (perimeter length, width, height, GPS location, depth) and hydrological parameters (temperature, dissolved oxygen, pH, irradiance, water movement) were measured and its map was produced, based on morphological measurements and biological evidence. Species composition and biotic cover were investigated by image analysis. The benthic community was dominated by poriferans, together with remarkable assemblages of scleractinians and polychaete serpulids and clearly reflected the sharp light and hydrological gradients from the entrance to the cave bottom. Furthermore, different phases were hypothesized for the genesis of the cave during sea regression and flooding periods. To be signaled is the record of Petrobiona massiliana, a sponge was protected under both Barcelona and Bern Convention and of some individuals of polychaete Serpulinae, which are still under description. [ABSTRACT FROM AUTHOR]

Anthropogenic nutrient input to coastal waters is one of the most common disturbances within inshore marine benthic communities. Organic enrichment in sediments leads to the reduction or disappearance of sensitive organisms, and influences the quality and quantity of primary producers which serve as food sources for the benthic fauna. Such changes, in turn, affect the energy flow and food-web interactions in benthic communities. To examine how organic enrichment may alter marine benthic trophic relationship, a stable isotope (δ13C and δ15N) analysis of the potential food sources and a range of meiofauna and polychaetes from an organically polluted and a relatively unpolluted site was compared in subtropical waters of Hong Kong. Results indicated that some omnivorous infauna shifted from a mainly carnivorous diet at the unpolluted site to a largely herbivorous diet at the organically polluted site. This dietary shift is likely to be related to the oxygen stress, prey limitation and increased abundance and nutritional quality of primary producers in the eutrophic area, resulting in an increase in utilization of plant materials as the major food source. The present findings suggest that such changes in trophic position induced by organic enrichment can provide further insights into the structure and function of coastal benthic communities under pollution stress.

Abstract Background It is known that aquaculture may produce negative environmental effects on marine ecosystems. Southern Chile is one of the most important salmon and mussel-producing areas in the world. Here we assess the ecological status of benthic communities near farming centers in Caucahue Channel, Chiloe, which has been used intensely for salmon and mussel production for 30 years. Methods The macrofauna, sediments and water column were characterized at distances of 5 to 100 m from three salmon and three mussel-producing centers. Information was also obtained from reference sites 500 to 3000 m from these aquaculture farms. The macrofauna and environmental conditions during winter were analyzed using uni- and multivariate analysis and the AZTI Marine Biotic Index (AMBI) as an indicator of benthic community condition. Results (i) There is a high degree of spatial dissimilarity in macrofauna and environmental variables among sampling sites and types of environments (far from or near farming centers) and between the northern and southern areas of the channel; (ii) sediment structure (mean grain size and percentage of total organic matter) correlated with the observed dissimilarities in macrofauna communities; and (iii) the level of perturbation according to AMBI was heterogeneous, with sites in the undisturbed/normal range to moderately disturbed/polluted. Conclusions We found a high spatial dissimilarity in benthic macrofauna and environmental variables among sampling sites, environmental types and between the northern and southern areas of the channel. AMBI and multivariate community-environment analysis are useful tools to define the level of perturbation of a geographic area at different spatial scales, using all the ecological information from each sample and replicates.

Altered ocean chemistry caused by ocean acidification (OA) is expected to have negative repercussions at different levels of the ecological hierarchy, starting from the individual and scaling up to the community and ultimately to the ecosystem level. Understanding the effects of OA on benthic organisms is of primary importance given their relevant ecological role in maintaining marine ecosystem functioning. The use of functional traits represents an effective technique to investigate how species adapt to altered environmental conditions and can be used to predict changes in the resilience of communities faced with stresses associated with climate change. Artificial supports were deployed for 1-y along a natural pH gradient in the shallow hydrothermal systems of the Bottaro crater near Panarea (Aeolian Archipelago, southern Tyrrhenian Sea), to explore changes in functional traits and metabolic rates of benthic communities and the repercussions in terms of functional diversity. Changes in community composition due to OA were accompanied by modifications in functional diversity. Altered conditions led to higher oxygen consumption in the acidified site and the selection of species with the functional traits needed to withstand OA. Calcification rate and reproduction were found to be the traits most affected by pH variations. A reduction in a community's functional evenness could potentially reduce its resilience to further environmental or anthropogenic stressors. These findings highlight the ability of the ecosystem to respond to climate change and provide insights into the modifications that can be expected given the predicted future pCO 2 scenarios. Understanding the impact of climate change on functional diversity and thus on community functioning and stability is crucial if we are to predict changes in ecosystem vulnerability, especially in a context where OA occurs in combination with other environmental changes and anthropogenic stressors. • Ocean acidification (OA) affect the distribution of traits within a community leading to the selection of specific functional traits. • Along with the selection of traits, OA led to differences in oxygen consumption between benthic communities following acidification gradient. • Altered acidified condition have a negative effect on the stability of the community resulting from changes in functional evennes of benthic communities. [ABSTRACT FROM AUTHOR]

Coral reef benthic communities have been mapped in broad categories, such as total coral cover, using remote sensing, yet we lack important details on how changes in benthic community composition translate to spectral changes observed in airborne and spaceborne data. Here, we carry out a spectral sensitivity analysis to enhance our quantitative understanding of benthic community reflectance spectra – or spectral communities – using a controlled simulation that incorporates field-based spectral libraries and endmember constituent modeling. Following the modeling phase, we apply the knowledge to the interpretation of airborne imaging spectroscopy data taken at 2 m resolution over two coral reefs in Hawaiʻi. We found that differences in organismic-scale spectra and their morphology contribute to patterns in the airborne data, enabling fine-scale differentiation between benthic community types. In doing so, we successfully determined the extent of two hyperdominant coral species (Porites lobata and Porites compressa) in the airborne data. Our findings suggest that imaging spectroscopy remains only partially explored for its potential in more detailed benthic mapping. Additional research that combines field- and remote sensing-based spectroscopy may advance ecosystem research and management on coral reefs. • A simulation that combines field-based spectra and endmember constituent modeling. • Sensitivity analyses of spectral variability in Hawaiian benthic communities. • Comparing modeled spectra with airborne imaging spectroscopy data. • Spectral signatures were found to discriminate between two dominant coral species. • High-order principal components revealed clustering based on benthic morphology. [ABSTRACT FROM AUTHOR]

The main fisheries of northern shrimp in Icelandic waters are located west and north of Iceland. These locations are studied in an annual survey to estimate stock size and distribution of northern shrimp. In July 2015, an additional survey was conducted to study the benthic community structure and function to describe the habitat where the northern shrimp fisheries take place. Underwater images were taken from 26 stations, grab samples were collected at 11 stations and in addition, by-catch was collected from the annual Icelandic shrimp survey in August 2015. The sampling sites, despite being distributed throughout a relatively large area north of Iceland, were rather uniform in relation to sediment type and fauna composition. The stations were similar in grain size and dominated by soft sediment of sand and silt/mud and soft sediment fauna. The infauna was mainly burrowing infauna with affinity to soft sediment and surface deposit feeding. The epifauna were free-living crawlers with affinity for predation feeding habit. No relationship with environment was observed for either the epifauna or the infauna. Species diversity and community composition did not vary with depth, probably because of the narrow depth range of the sites. This study provides the first data on benthic in- and epifauna in northern shrimp fishery locations north of Iceland, which can later be used to estimate possible changes and/or the effect of shrimp fishing within this area. [ABSTRACT FROM AUTHOR]

The Aysén region of Chile (North Patagonia), has had limited studies on the effectiveness of management and exploitation areas of benthic resources, and performance relative to open access areas in this region has never been evaluated. We evaluated seven management areas (MAs) and five open access areas (OAAs) between 43.9°S and 45.2°S for exploitation intensity of three commercial species (Concholepas concholepas, Loxechinus albus, and Ameghinomya antiqua) together with characterization of the benthic community. Indicators based on size, density and weight were used to evaluate exploitation intensity of commercial species. Associated benthic communities were evaluated considering density, species composition, and community structure. We found a high species richness and a community structure with low variability between MAs and OAAs. Low densities and small sizes classes of C. concholepas in most of the areas indicated high exploitation intensity in both MAs and OAAs. In this context, a permanent ban to harvest C. concholepas within OAAs may need to be reevaluated since with no enforcement and monitoring, the exploitation status of this species remains unclear in these areas. L. albus in most areas were absent in the harvestable sizes, which could be indicating high exploitation intensity in both regimes. High densities and small sizes of C. concholepas and L. albus in some MAs, indicated a potential recruitment zones which bears further investigation. A. antiqua, showed better conditions than other commercial species evaluated, with no significant differences in densities and size-based indicators when comparing OAAs and MAs. Benthic communities were dominated numerically by the Echinoidea class in both MAs and OAAs, with L. albus, Arbacia dufresnii and Pseudechinus magellanicus being the dominant species. High densities of sea urchins co-occurring with low coverage of macroalgae found in MAs-Gala could indicate that a sea urchin barren was dominant during the study period. On the other hand, high densities of Cosmasterias lurida, a predatory sea star, in conjunction with low densities of C. concholepas in most of the studied areas suggested that a shift in predator roles is occurring. No differences were estimated in terms of fisheries indicators and benthic community structure across the two management regimes, suggesting the poor performance of MAs in Aysén region. Our data also support the need to improve monitoring of MAs especially with respect to associated benthic community incorporating a broader spatial scale.

Macrobenthos are important bioindicators of organic and nutrient pollution. The present study used the macrobenthos‐based rapid bioassessment protocol (RBP II) to study the effects of treated textile effluent inputs into a natural stream ecosystem connected to a wetland marsh. Three reference sites and three sites receiving point source inputs from a textile effluent treatment plant were selected. The physical and chemical parameters, and the abundance and diversity of macrobenthos at each site, were assessed during the rainy and dry seasons of 2020. Although the water quality parameters at the sites representing the point source inputs did not exceed the standard textile effluent discharge limits, a significant influence on the macrobenthic community composition was observed at the effluent discharge receiving sites. The dominant macrobenthos in the ecosystem (Baetis sp., Leptophlebia sp; Tubifex sp.) exhibited significant correlations with lead, copper, chromium and cadmium concentrations of the water and sediments. The Shannon–Weiner Diversity Index, Family Biotic Index, EPT Index and EPT/C ratio used in the rapid bioassessment protocol indicated significantly strong correlations with the water and sediment quality parameters, demonstrating their suitability to be used as a tool for biological measurements in aquatic ecosystems receiving textile effluents. [ABSTRACT FROM AUTHOR]

The Huangmao Island dumping area is adjacent to the Pearl River Estuary in the South China Sea. From its first dumping activity in 1986 to 2017, 6750 × 104 m3 dredged materials were dumped in this dumping area. Sediment pollution levels, ecological risk, and benthic communities in 2011–2017 were evaluated; the results showed that the concentrations of the heavy metals (HMs; except Hg) in surface sediments of the dumping area met the class I standard of marine sediment quality (GB 18668-2002). HMs in the surface sediments were relatively high in the northern and central areas but relatively low in the south of the dumping area. Speculation was that the spatial variation in HM concentrations might be caused by dumping activities. The Nemerow index implied that the contaminated area was mainly in the north of the dumping area (S1, S2, and S3), where the dumping amount was the largest. The potential ecological risk (Eir) indices of Zn, As, Cu, and Pb indicate that these metals posed a low risk to the ecosystem of the dumping area, whereas Cd and Hg posed a high risk at some stations. The geoaccumulation indices (Igeo) of Zn, As, Cu, and Pb specified no pollution or light pollution in the study area, whereas those of Cd and Hg in most years indicated mild contamination levels. Benthic organisms in the study area were arthropods, chordates, annelids, mollusks, echinoderms, nemertinean, coelenterate, and echiuran, among which arthropods were the most abundant. The abundance of taxa and density of benthic organisms had a little difference among the stations within the dumping area, but were significantly lower than those of the stations outside the dumping area. In addition, non-metric multidimensional scaling analysis confirmed that the observed patterns separated the stations within the dumping area from stations outside the dumping area. The evaluation results of the HMs revealed that the dumping area with a large dumping amount was more severely polluted. Dumping dredged materials seemed to have a negative impact on the benthic community in the dumping area. [ABSTRACT FROM AUTHOR]

Historical traces of organisms on the seafloor, such as shells and tubes, constitute the ecological memory of ancient benthic assemblages and serve as an important resource for understanding the assembly of modern communities. Archeological shipwrecks are particularly interesting submerged substrata for both their archeological and biological implications. For the first time, we studied the species composition and life-history traits of dominant organisms in the benthic assemblage on a bronze Carthaginian naval ram, which sank more than two thousand years ago in the Southern Tyrrhenian Sea. By comparing the species composition of the ram assemblage with those of the surrounding habitats, we inferred possible colonization patterns for the ram and discussed the informative role of the shipwreck as a proxy of marine biodiversity. The ram assemblage was rich in species, including both sessile (bryozoans, serpulid polychaetes, and few bivalves) and motile (gastropods) species. Sexual reproduction with free-spawning fertilization and long-duration larvae characterized most species. The long submersion time of the ram, together with the reproductive strategies, growth forms, and motility of the dominant species were key factors shaping the community of the ram. The ram itself offers an archeological artifact of inestimable value, but our analysis revealed it to be an effective collector of fauna from the surrounding seabed. The ram community hosted species from a range of nearby natural habitats (mostly coralligenous, detritic bottoms, and zoosteracean meadows) and thus served as a proxy for marine biodiversity on the surrounding seabed. We conclude that the presence of many species on the ram that commonly occur in adjacent habitats of great environmental value was informative and highlight the important marine biodiversity in the area of the Aegadian archipelago.

Reef monitoring programmes often focus on limited sites, predominantly on reef slope areas, which do not capture compositional variability across zones. This study assessed spatial and temporal changes in hard coral cover at four hierarchical spatial scales. ~ 55,000, geo-referenced photoquadrats were collected annually from 2002 to 2018 and analysed using artificial intelligence for 31 sites across reef flat and reef slope zones on Heron Reef, Southern Great Barrier Reef, Australia. Trends in hard coral cover were examined at three spatial scales: (1) "reef scale", all data; (2) "geomorphic zone scale"—north/south reef slope, inner/outer reef flat; and (3) "site scale"—31 sites. Coral cover trajectories were also examined at: (4) "sub-site scale"—sub-division of sites into 567 sub-sites, to estimate variability in coral cover trajectories via spatial statistical modelling. At reef scale coral cover increased over time to 25.6 ± 0.4 SE % in 2018 but did not recover following disturbances caused by disease (2004–2008), cyclonic conditions (2009) or severe storms (2015) to the observed pre-disturbance level (44.0 ± 0.7 SE %) seen in 2004. At geomorphic zone scale, the reef slope had significantly higher coral cover than the reef flat. Trends of decline and increase were visible in the slope zones, and the southern slope recovered to pre-decline levels. Variable coral cover trends were visible at site scale. Furthermore, sub-site spatial modelling captured eight years of coral recovery that occurred at different times and magnitudes across the four geomorphic zones, effectively estimating variability in the trajectory of the reef's coral community. Derived spatial predictions for the entire reef show patchy coral recovery, particularly on the southern slope, and that recovery hotspots are distributed across the reef. These findings suggest that to fully understand and interpret coral decline or recovery on a reef, more accurate assessment can be achieved by examining sites distributed within different geomorphic zones to capture variation in exposure, depth and consolidation. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) metabarcoding is an emerging tool to estimate diversity by combining DNA from the environmental samples and the high-throughput sequencing. Despite its wide use in estimating eukaryotic diversity, many factors may bias the results. Maker choice and reference databases are among the key issues in metabarcoding analyses. In the present study, we compared the performance of a novel 28S rRNA gene marker designed in this study and two commonly used 18S rRNA gene markers (V1-2 and V9) in estimating the eukaryotic diversity in the deep-sea sediments. The metabarcoding analyses based on the sediment surveys of the Okinawa Trough found that more eukaryotic taxa were discovered by 18S V9 than 28S and 18S V1-2, and that 18S V9 also performed better in metazoan recovery than the other two markers. Although a broad range of taxa were detected by the three metabarcoding markers, only a small proportion of taxa were shared between them even at the phylum level. The non-metric multidimensional scaling (NMDS) analysis also supported that communities detected by the three markers were distinct from each other. In addition, different communities were resolved by different reference databases (NCBI nt vs. SILVA) for the two 18S markers. Combining the three markers, annelids were found to be the most abundant (44.9%) and diverse [179 operational taxonomic units (OTUs)] metazoan group in the sediments of the Okinawa Trough. Therefore, multiple independent markers are recommended to be used in metabarcoding analyses during marine diversity surveys, especially for the poorly understood deep-sea sediments.

The Ross Sea, Antarctica, is amongst the least human-impacted marine environments, and the site of the world’s largest Marine Protected Area. We present research on two components of the Ross Sea benthic fauna: mega-epifauna, and macro-infauna, sampled using video and multicore, respectively, on the continental shelf and in previously unsampled habitats on the northern continental slope and abyssal plain. We describe physical habitat characteristics and community composition, in terms of faunal diversity, abundance, and functional traits, and compare similarities within and between habitats. We also examine relationships between faunal distributions and ice cover and productivity, using summaries of satellite-derived data over the decade prior to our sampling. Clear differences in seafloor characteristics and communities were noted between environments. Seafloor substrates were more diverse on the Slope and Abyss, while taxa were generally more diverse on the Shelf. Mega-epifauna were predominantly suspension feeders across the Shelf and Slope, with deposit feeder-grazers found in higher or equal abundances in the Abyss. In contrast, suspension feeders were the least common macro-infaunal feeding type on the Shelf and Slope. Concordance between the mega-epifauna and macro-infauna data suggests that non-destructive video sampling of mega-epifauna can be used to indicate likely composition of macro-infauna, at larger spatial scales, at least. Primary productivity, seabed organic flux, and sea ice concentrations, and their variability over time, were important structuring factors for both community types. This illustrates the importance of better understanding bentho-pelagic coupling and incorporating this in biogeographic and process-distribution models, to enable meaningful predictions of how these ecosystems may be impacted by projected environmental changes. This study has enhanced our understanding of the distributions and functions of seabed habitats and fauna inside and outside the Ross Sea MPA boundaries, expanding the baseline dataset against which the success of the MPA, as well as variability and change in benthic communities can be evaluated longer term.

The karstic Una River is one of the larger tributaries of the Sava River. Although being a part of Balkan biodiversity hot-spot, aquatic macroinvertebrates of the Una are rarely studied. The aquatic macroinvertebrates sampling was performed in the summer of 2015 throughout the upper river stretch covering the Una and its tributaries situated in the Una National Park (Una NP). A rich community consisting of 130 macroinvertebrate taxa, with dominance of Trichoptera and Ephemeroptera, was detected. A snail Sadleriana sp. and endemic gammarid Echinogammarus acarinatus were found to be dominant taxa in terms of percentage participation and frequency of occurrence. Mollusca and Crustacea were found to be the most abundant groups, with higher abundance in the Una River than its tributaries. Although a higher overall taxa richness was found in tributaries, calculated biotic indices and evenness pointed to greater diversity in the Una River. Additionally, BMWP and ASPT scores were also higher in the Una River than its tributaries. Calculated Jaccard index value pointed to moderate faunistic similarity between investigated communities. Obtained results suggest that investigated upper stretch of the Una River harbours a high diversity and rather homogenous macroinvertebrate community. [ABSTRACT FROM AUTHOR]

• One of very few studies of biodiversity-ecosystem function in real-world settings. • Quantified biodiversity and functions in a water quality gradient of a coastal megacity. • Biodiversity, primary and secondary productivity are diminished in highly impacted areas. • Ecosystem functionality is context-dependent due to eutrophication and biodiversity effects. • Opportunistic organisms may fill gaps in functional roles in degraded habitats. Coastal marine ecosystems are integral in providing numerous ecosystem functions and services. However, intense and chronic anthropogenic stressors often impact marine ecosystems surrounding highly urbanized, densely populated coastal megacities. The associated reduction of water quality and biodiversity of these ecosystems potentially erodes ecosystem functions and provision of services. While there is general consensus that greater biodiversity supports a multitude of ecosystem functions, evidence from marine ecosystems in real-world settings is lacking. In this study, we evaluated the influence of water quality on benthic and fish assemblages, as well as quantified six key ecosystem functions in coastal waters of Hong Kong. Hong Kong's marine ecosystems are marred with long-term damage that is directly linked with rapid economic growth and anthropogenic activities. We found that water quality significantly affected community composition and clustered assemblages into separate groups related to strength of impact: high impact sites were generally dominated by bivalves and small, opportunistic organisms such as damselfish (Pomacentrinae) and cardinalfish (Apogonidae); low impact sites were dominated by macroalgae, bryozoa, and commercially important piscivores such as groupers (Epinephelinae) and seabreams (Sparidae). Ecosystem function tests showed that low impact sites were much more productive than high impact sites, with 15-times greater macroalgal cover and 5-times higher fish biomass. On the other hand, herbivory and predation rates were context-dependent due to underlying biodiversity effects such as selection, complementarity, and competition. Eutrophication increased decomposition and reduced carbon sequestration, but excessive nutrient input could have suppressed decomposer activities via hypoxia. Therefore, we show that in high impact sites where top-down control is removed, resilient and opportunistic organisms such as cardinalfishes and sea urchins may expand to fulfill functional roles, effectively maintaining ecosystem functions such as predation and herbivory in degraded habitats. Contrary to general consensus, this study demonstrates the merit in conserving even highly impacted marine habitats due to their persistent ecosystem functionality despite chronic water quality issues and shifts in benthic and fish assemblages. [ABSTRACT FROM AUTHOR]

We investigated relationships between features of benthic macrofaunal communities and geochemical parameters in and around microbial mat-covered sediments associated with a methane seepage on Sakata Knoll in the eastern Japan Sea. A depression on top of the knoll corresponds to a gas-hydrate-bearing area with seepage of methane-rich fluid, and microbial mats cover the seafloor sediments. Sediment cores were collected at three sites for this study: one within a microbial mat, a second a few meters outside of the microbial mat, and a third from a reference site outside the gas-hydrate-bearing areas. Morphological analysis showed that the site inside the microbial mat had higher macrofaunal density and biomass compared with the other sites. 18S rRNA gene analysis showed that annelids were dominant in the surface sediment inside the microbial mat with the possible occurrence of microbial anaerobic oxidation of methane (AOM), whereas in the surface sediments outside the microbial mat and at the reference site the predominant species belonged to phylum Cercozoa. Morphological analysis also showed that the surface sediment inside the microbial mat noticeably favored annelids, with dorvilleid Ophryotrocha sp. and ampharetid Neosabellides sp. identified as major constituents. Statistical analysis showed that sulfidic sediment conditions with concentrations of H 2 S up to 121 μM resulting from AOM likely resulted in the predominance of annelids with tolerance to sulfide. Both the 18S rRNA genes and macrofaunal characteristics showed that benthic biodiversity among the three sites was greatest outside the microbial mat. The site outside the microbial mat may represent geochemical transition conditions, including a lower rate of upward methane gas-flow compared with the site inside the microbial mat. The high biodiversity there might result from the presence of species specifically suited to the transition zone as well as species also found in photosynthesis-based communities of the background environment. [Display omitted] • Microbial mats overlie methane seepage sediments on Sakata Knoll in the Japan Sea. • Methane diffusion affects redox conditions and organic matter supply in the sediments. • Benthic communities dominated by annelids are related to sulfidic sediments. • The environment outside the microbial mats has higher biodiversity than inside. [ABSTRACT FROM AUTHOR]

• Current bioassessment methods are not well suited to account for complex natural environmental gradients. • Proposed method uses correlated residual occurrence to estimate biological condition. • Method estimates condition without assumption of "minimally disturbed" conditions present in sample. • Method allows estimate of condition to be partitioned to potential contributing stressors. Bioassessment of complex and heterogeneous ecosystems is a challenge when there are multiple, strong, natural environmental gradients; unknown, or spatially varying, mixtures of stressors; and large numbers of taxa with unknown responses to both the environmental gradients and the stressors. Current methods of bioassessment are not designed for use under this set of constraints. To address this gap, we have developed an assessment method appropriate for well-sampled, heterogeneous systems with many taxa. In the bioassessment described below, we model taxa occurrence as a function of natural environmental gradients, then use residual covariance patterns between all pairs of taxa to estimate the impact of human disturbance across sites as a latent construct. The derivation of the method from an underlying causal model allows the metric value at each site and the associated taxa responses to be partitioned into contributions from a set of putative stressors. We apply this method as a case study to the subtidal benthic invertebrate community of Puget Sound, WA (USA) and demonstrate a partial decomposition of the metric values to a set of stressors including sediment organic carbon, nitrogen, metals, and organic pollutants. While this method provides new opportunities to estimate, communicate, and understand the ecological condition of complex, heterogeneous ecosystems, due to the requirement for broad, detailed data to inform its estimates, it will likely be most appropriate for monitoring programs. [ABSTRACT FROM AUTHOR]

Environmental variability within estuaries and lagoons creates environmental gradients. Spatial variations in environments associated with environmental gradients shape spatial variations in primary producer and invertebrate communities. However, whether larger spatial variations are linked to greater temporal variations in the communities remained unclear. To understand the linkage between spatial and temporal variations in the communities and the factors shaping these variations, we targeted various functional groups of primary producers and invertebrates (epifauna) in eelgrass (Zostera marina) ecosystems in lagoons with and without distinct salinity gradients. We tested the following hypotheses: 1) larger spatial variation in the primary producer biomasses and epifaunal community structures (abundance, biomass, and species richness) are associated with greater temporal variation in the structures, and 2) salinity would be a more pronounced factor than water temperature and biomasses of primary producers in shaping the community structures in the lagoon with a salinity gradient. Our results showed that temporal and spatial variations in the primary producer biomasses and community structures of epifauna were larger in the lagoon with a salinity gradient. Moreover, salinity, water temperature, and the biomasses of primary producers affected the spatio-temporal variations in the community structures of epifauna, regardless of the presence of the gradients. We present from these results the connection between spatial and temporal variations of the primary producer and epifaunal community structures and the effects of abiotic and biotic factors shaping the communities. [Display omitted] • Environmental variability, such as salinity, shapes invertebrate communities in estuaries and lagoons. • We tested if eelgrass communities are temporally and spatially variable in the presence of the distinct salinity gradient. • Temporal and spatial variations in the communities were larger in the lagoon with a distinct salinity gradient. • The effects of salinity and water temperature on the communities were stronger in the lagoon with a distinct salinity gradient. • The effects of primary producer biomasses on the communities were stronger in the lagoon with a distinct salinity gradient. [ABSTRACT FROM AUTHOR]

The Tremiti Islands Archipelago is located in the Central-Southern Adriatic Sea and is characterized by a strong karst activity. Due to their landscape, geological, hydrological, archaeological, and historical value, Tremiti Islands are considered a geomorphosite. We carried out a preliminary, non-destructive survey by studying the speleological and biological features of the submerged sea cave Elle, located at Cala Sorrentino (Capraia Island), representing an EU Natura 2000 Priority Habitat. Topographic (perimeter length, width, height, GPS location, depth) and hydrological parameters (temperature, dissolved oxygen, pH, irradiance, water movement) were measured and its map was produced, based on morphological measurements and biological evidence. Species composition and biotic cover were investigated by image analysis. The benthic community was dominated by poriferans, together with remarkable assemblages of scleractinians and polychaete serpulids and clearly reflected the sharp light and hydrological gradients from the entrance to the cave bottom. Furthermore, different phases were hypothesized for the genesis of the cave during sea regression and flooding periods. To be signaled is the record of Petrobiona massiliana, a sponge was protected under both Barcelona and Bern Convention and of some individuals of polychaete Serpulinae, which are still under description.