Integrating rapid habitat mapping with community metrics and functional traits to assess estuarine ecological conditions: A New Zealand case study.

Estuarine ecosystems are under pressure from anthropogenic stressors in many parts of the world. In a New Zealand estuary, we integrated rapid habitat mapping, univariate and multivariate benthic community metrics and functional traits-based metrics to provide a holistic assessment of its ecological condition. Our integrative approach identified 11 different habitat classes across the study estuary and revealed how univariate, multivariate, and functional traits-based metrics varied spatially. Variation was driven mainly by sedimentary conditions, particularly, the sediment's organic matter and silt-clay content. Degraded conditions were apparent in several parts of the estuary, which overlapped with areas showing high concentrations of decaying algae, anoxic conditions, and low values of univariate and functional metrics. Our holistic approach, integrating mapping and quantitative community assessments, provided a more complete picture of estuarine conditions and enabled us to identify locations across the estuary with the greatest potential for restoration success.

First Report of Bothynus striatellus (Coleoptera: Melolonthidae) Damaging Lucerne Crops in Argentina.

We report for the first time that larvae of the genus Bothynus Hope (Coleoptera: Melolonthidae) caused economic damage to lucerne (Medicago sativa L., Fabaceae) crops in General Acha, province of La Pampa, Argentina. In two consecutive years (2021 and 2022), this insect infested 150 ha of lucerne, causing seedling losses of 80 ha. Based on soil sampling and laboratory insect rearing, the species was identified as Bothynus striatellus (Faimaire) (Coleoptera: Melolonthidae). Information is given here on the damage recorded in this forage crop, the density of the larvae observed at the time of damage assessment and the morphological characteristics of the third instar larvae reported in this crop in Argentina.

Impacts of Millipedes on Acari and Collembola Communities-A Microcosm Experiment.

Ecosystem engineers influence the structure and function of soil food webs through non-trophic interactions. The activity of large soil animals, such as earthworms, has a significant impact on the soil microarthropod community. However, the influence of millipedes on soil microarthropod communities remains largely unknown. In this microcosm experiment, we examined the effects of adding, removing, and restricting millipede activity on Acari and Collembola communities in litter and soil by conducting two destructive sampling sessions on days 10 and 30, respectively. At the time of the first sampling event (10 d), Acari and Collembola abundance was shown to increase and the alpha diversity went higher in the treatments with millipedes. At the time of the second sampling event (30 d), millipedes significantly reduced the Collembola abundance and alpha diversity. The results were even more pronounced as the millipedes moved through the soil, which caused the collembolans to be more inclined to inhabit the litter, which in turn resulted in the increase in the abundance and diversity of Acari in the soil. The rapid growth of Collembola in the absence of millipedes significantly inhibited the abundance of Acari. The presence of millipedes altered the community structure of Acari and Collembola, leading to a stronger correlation between the two communities. Changes in these communities were driven by the dominant taxa of Acari and Collembola. These findings suggest that millipedes, as key ecosystem engineers, have varying impacts on different soil microarthropods. This study enhances our understanding of biological interactions and offers a theoretical foundation for soil biodiversity conservation.

Waste barrel contamination and macrobenthic communities in the San Pedro Basin DDT dumpsite.

Industrial waste barrels were discarded from 1947 to 1961 at a DDT dumpsite in the San Pedro Basin (SPB) in southern California, USA at ~890 m. The barrels were studied for effects on sediment concentrations of DDX, PCBs, PAHs and sediment properties, and on benthic macrofaunal assemblages, including metazoan meiofaunal taxa >0.3 mm. DDX concentration was highest in the 2-6 cm fraction of the 10-cm deep cores studied but exhibited no correlation with macrofaunal density, composition or diversity. Macrofaunal diversity was lowest and distinct in sediments within discolored halos surrounding the barrels. Low macrobenthos density and diversity, high dominance by Entoprocta, and numerical prevalence of large nematodes may result from the very low oxygen concentrations in bottom waters (< 4.4 µM). There is potential for macrofauna to remobilize DDX into the water column and ultimately the food web in the SPB.

Does the incorporation of shell waste from aquaculture in the construction of marine facilities affect the structure of the marine sessile community?

The growth of the human population causes significant harm to ecosystems, directly affecting the biological diversity of coastal areas by replacing natural habitats with artificial structures such as breakwaters, ports, and marinas. The hard substrate from those marine facilities lacks the topographic complexity of natural habitats. Because of that, artificial habitats usually do not support a diverse community to the same extent as rocky shores in the surroundings. To address this issue and bring a strategic solution to the improper disposal of shell waste from aquaculture farms, we evaluated how increasing the environmental heterogeneity of walls by incorporating mussel and oyster shells on artificial concrete affected the diversity of sessile organisms from the subtidal zone. Adding shells to concrete positively affected ascidians' richness. Substrates with added shells supported more species than flat substrates in total. They promoted species that did not occur on flat substrates that simulated the traditional walls of marinas and harbors. However, it did not affect the number of bryozoans and the average species richness. Consequently, incorporating shells resulted in communities with completely distinct structures from those on flat substrates. Adding shells affected the community structure, reducing the dominance by the exotic bryozoan Schizoporella errata, and promoting the occurrence of other groups, such as ascidians. Using shell residues from aquaculture on marina walls adds substrate for colonization. Still, it is also likely to provide refuges for fragile and vulnerable organisms, like crevices and pits in natural habitats. Because of that, the increment in diversity was mostly group-specific and restricted to ascidians. This research reinforces the importance of creating complex artificial coastal structures, inspired by the blue economy, for a more heterogeneous coverage of sessile communities and reduced presence and dominance of exotic species. Thus, the strategy tested here, besides the effects on the sessile community, also supports efforts to reduce inappropriate waste disposal in the environment.

Decadal changes of macrofauna community in a semi-enclosed Bay of Yueqing in East China Sea.

To reveal the long-term variation of macrofauna community in Yueqing Bay, an aquacultural bay famous for its shellfish culturing in the East China Sea, macrofauna samples were collected in three period from 2002 to 2003 and 2006-2007 to 2020-2021. The results show that macrofaunal community structure in this area has changed significantly (ANOSIM, p < 0.01) in nearly two decades with significant decreases in species number, biodiversity index and average biomass. Meanwhile, the taxa composition also changed significantly as the dominance of annelid increased while that of mollusks, echinoderms and vertebrates decreased. As a consequence of the variation of taxa composition and total biomass, macrofauna community showed a tendency of miniaturization as individuals with smaller body size and lower biomass dominated the community. According to the results of CCA analysis, temperature, salinity and dissolved oxygen content were the main environmental factors that restricted the species composition of macrofauna community. Further studies still needed to reveal the main reasons that cause the variation of macrofauna community. Overall, the results of this study suggest that the present status of Yueqing Bay benthic ecosystem is concerning from a macrobenthos perspective, as the biodiversity index and biomass of macrofauna decreased significantly. Effective measures should be taken in urgently to restrain the safety and function of coastal ecosystems.

The power of Posidonia oceanica meadows to retain microplastics and the consequences on associated macrofaunal benthic communities.

In the coastal environment, a large amount of microplastics (MPs) can accumulate in the sediments of seagrass beds. However, the potential impact these pollutants have on seagrasses and associated organisms is currently unknown. In this study, we investigated the differences in MPs abundance and composition (i.e., shape, colour and polymer type) in marine sediments collected at different depths (-5 m, -15 m, -20 m) at two sites characterized by the presence of Posidonia oceanica meadows and at one unvegetated site. In the vegetated sites, sediment samples were collected respectively above and below the upper and lower limits of the meadow (-5 m and -20 m), out of the P. oceanica meadow, and in the central portion of the meadow (-15 m). By focusing on the central part of the meadow, we investigated if the structural features (i.e. shoots density and leaf surface) can affect the amount of MPs retained within the underlying sediment and if these, in turn, can affect the associated benthic communities. Results showed that the number of MPs retained by P. oceanica meadows was higher than that found at the unvegetated site, showing also a different composition. In particular, at vegetated sites, we observed that MPs particles were more abundant within the meadow (at - 15 m), compared to the other depths, on unvegetated sediment, with a dominance of transparent fragments of polypropylene (PP). We observed that MPs entrapment by P. oceanica was accentuated by the higher shoots density, while the seagrass leaf surface did not appear to have any effect. Both the abundance and richness of macrofauna associated with P. oceanica rhizomes appear to be negatively influenced by the MPs abundance in the sediment. Overall, this study increases knowledge of the potential risks of MPs accumulation in important coastal habitats such as the Posidonia oceanica meadows.

Assessing sandy beach macrofaunal assemblages across geographically diverse morphodynamic environments.

While the physical characteristics of sandy beaches play a significant role in shaping the macrofaunal community features through morphodynamics, regional environmental factors may also account for deviations from the expected patterns. Here, we assess the concurrent effects of local morphodynamic factors and regional variables, such as sea surface temperature (SST), salinity, and chlorophyll-a (chl-a), on species richness and abundance of intertidal macrofaunal assemblages in four sandy beaches located along the estuarine gradient generated by the Río de la Plata (RdlP) in the southwestern Atlantic Ocean. Species richness was higher in dissipative beaches compared to intermediate ones, consistent with the predictions of the Swash Exclusion Hypothesis. However, this trend was not observed for total abundance, which significantly increased with chl-a. Both local and regional-scale environmental factors, such as salinity and chl-a, proved to be significant predictors in the arrangement of these communities. These results further support previous findings that highlight the critical role of the estuarine gradient of the RdlP in shaping life-history traits, population structure, and abundance of the resident intertidal macrofauna at both local and regional scales. The study underscores the importance of integrating environmental factors operating at different spatial scales to decipher community patterns in these physically-controlled environments.

Good-Moderate boundary setting for the environmental status assessment of the macrozoobenthos communities with the Benthic Quality Index (BQI) in the south-western Baltic Sea.

The status assessment of the macrofauna community under the European Marine Strategy Framework Directive (MSFD) requires threshold values that mark the transition from good to moderate conditions (G-M boundaries). Using the example of the Benthic Quality Index (BQI) in the south-western Baltic Sea, we demonstrate the possibilities and restrictions of i) defining G-M boundaries using reference areas, historical data and a statistical method and ii) the subsequent evaluation of the resulting G-M boundaries using disturbance data. The historical data from the period 1911 to 1929 proved to be unsuitable for defining G-M boundaries due to their data quality. The G-M boundaries calculated using the statistical method delineated high disturbance values more reliably than those based on reference areas. We conclude that disturbance data are very useful to evaluate G-M boundaries for their suitability, but data on all state conditions are needed.

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

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

Trophic niches of macrobenthos: Latitudinal variation indicates climate change impact on ecosystem functioning.

Benthic food-web structure and organic matter (OM) utilization are important for marine ecosystem functioning. In response to environmental changes related to the ongoing climate change, however, many benthic species are shifting their ranges to colder regions, which may lead to altered community composition, but it remains largely unknown how it will affect ecosystem functioning. Here, stable isotope analysis was used to study benthic OM utilization and food-web structure and to assess whether their spatial patterns reflect today's community differentiation among biogeographic regions and depth zones. Benthic fauna and OM mixtures were collected from two depth zones (100-150 m vs. 200-250 m) within a temperate, two sub-Arctic, and an Arctic fjord along a latitudinal gradient (59-78° N) that was used as a space-for-time substitution to assess the impact of climate change. Our results showed that Arctic and temperate communities are functionally different. Arctic communities were characterized by a strong resource partitioning among different feeding types, irrespective of depth zone. In contrast, all feeding types in temperate communities seemed to rely on sedimentary OM. The sub-Arctic presented a transition zone. In the sub-Arctic, shallower communities resembled Arctic communities, suggesting a functional transition between temperate and sub-Arctic regions. Deeper sub-Arctic communities resembled temperate communities, suggesting a functional transition between the sub-Arctic and Arctic regions. This implies that the regions north of the current transitions (deep Arctic and shallow sub-Arctic) are most likely to experience functional changes related to an altered OM utilization in benthic food webs in response to climate change.

Biodiversity patterns of the benthic macrofaunal communities across the intertidal sedimentary shores of two Antarctic islands.

Antarctic benthic ecosystems support a unique fauna characterized by high levels of diversity and endemism. However, our knowledge of the macrofauna communities across the Antarctic intertidal sedimentary shore is limited, and their fundamental ecological features, including spatial variability, remain poorly understood. This study aimed to investigate the abundance, community structure (i.e. taxa-specific abundance), and biodiversity patterns (α-, ß-, and λ-diversity) of benthic macrofauna communities on intertidal sedimentary shores of two Antarctic islands (South Shetland archipelago, N of Antarctic Peninsula): Livingston and Deception. We conducted a quantitative sampling during two Austral summer campaigns (2004 and 2005), studying eleven intertidal sites, with five sites located on Livingston and six on Deception. Our results demonstrated a significantly higher abundance of intertidal benthic macrofauna communities on Livingston than on Deception. Furthermore, significant differences in community structure were observed between the two islands. In terms of biodiversity patterns, there were no significant differences in the number of taxa within communities (α-diversity) between the two islands. However, significant differences in the variation of community composition (determined by the number and identity of taxa) between intertidal sites (ß-diversity) were observed, shedding light on the higher total taxa count (λ-diversity) on Livingston compared to Deception. We suggest that the island-specific characteristics (e.g., granulometric characteristics, ice disturbance, sedimentation rates, and geothermal activity) determine the differences observed in macrofauna communities. However, other ecological processes and factors are operating on different spatial and temporal scales (e.g., population dynamics, biotic interactions, oceanographic conditions, and climate change) that influence the occurrence and abundance of macrofaunal taxa. Our findings contribute to the fundamental understanding of the spatial variability of these communities and provide essential information for better management decisions and conservation practices in Antarctic coastal ecosystems.

Microplastic ingestion in aquatic and soil biota: A comprehensive review of laboratory studies on edible size and intake pattern.

Microplastic contamination is ubiquitous and can be transferred through the food chain to humans. However, studies on microplastic size have mainly focused on large animals with a body length >20 mm. To address this gap, we conducted a comprehensive review of 169 laboratory studies to determine the edible size of microplastics for macrofauna and flora in aquatic and soil biota. Our findings indicate that microplastics with a size of <300 µm and 1 µm, respectively, are edible for these organisms, which are positioned at the base of the food chain. We also analyzed intake and depuration patterns and identified factors affecting microplastic ingestion. Our study fills an important knowledge gap by identifying the range of microplastic sizes that can enter the food chain and be transferred to humans. The study findings have strong implications for the ecological risk assessment of microplastics and suggest a starting point for mitigating this threat.

Spatial structure and biodiversity of macrofauna around marine munition dumpsites - A case study from the Baltic Sea.

Coastal German waters contain about 1.6 million tons of dumped munition, mostly left after World Wars. This study investigated the benthic macrofauna around the 'Kolberger Heide' munition dumpsite (Baltic Sea). A total of 93 macrofauna grab samples were obtained in the proximity of the munition dumpsite and in reference areas. Environmental variables analysed included the latitude/longitude, depth, terrain ruggedness, sediment grainsize distribution, TNT concentration in the bottom water and distance to the centre of munition dumpsite. The overall abundance, biomass and diversity varied among these groups, though demonstrated no clear differences regarding the proximity to munition and modelled near-bottom dissolved TNT. Among individual taxa, however, a total of 16 species demonstrated significant correlation with TNT concentration. Moreover, TNT may serve as a predictor for the distribution of three species: molluscs Retusa truncatula, Varicorbula gibba and polychaete Spio goniocephala. Possible reasons for the species distribution including their biological traits are discussed.

Climate dependence of the macrofaunal effect on litter decomposition-A global meta-regression analysis.

Litter decomposition by microorganisms and animals is influenced by climate and has been found to be higher in warm and wet than in cold and dry biomes. We, however, hypothesized that the macrofaunal effect on decomposition should increase with temperature and aridity since larger animals are more tolerant to aridity than smaller organisms. This hypothesis was supported by our global analysis of macrofauna exclusion studies. Macrofauna increased litter mass loss on average by 40%, twofold higher than the highest previous estimation of macrofaunal effect on decomposition. The strongest effect was found in subtropical deserts where faunal decomposition had not been considered important. Our results highlight the need to consider animal size when exploring climate dependence of faunal decomposition, and the disproportionately large role of macrofauna in regulating litter decomposition in warm drylands. This new realization is critical for understanding element cycling in the face of global warming and aridification.

The high biodiversity of benthic organisms in a coastal ecosystem revealed by an integrative approach / A alta biodiversidade de organismos bentônicos em um ecossistema costeiro revelada por uma abordagem integrativa

Abstract Increasing habitat modification and species loss demand consistent efforts to describe and understand biodiversity patterns. The BIOTA/FAPESP Program was created in this context and it has been a successful initiative to promote studies on biodiversity and conservation in Brazil. The BIOTA/Araçá is an interdisciplinary project that provided a detailed evaluation of the biodiversity of Araçá Bay, a coastal seascape located on the North coast of the state of São Paulo, Southeast Brazil. The bay encompasses multiple habitats, such as beaches, mangroves, rocky shores, and a tidal flat, and provides important ecosystem services. Unfortunately, the bay is the subject of complex social-environmental conflicts that oppose economic, social, and environmental demands (i.e., the expansion of neighboring harbor activities vs. small-scale artisanal fisheries and protection of biodiversity). The present study presents a survey of the benthic species occurring in the different habitats of Araçá Bay, including data obtained during the BIOTA/Araçá project and previous assessments of the area. The benthic species play an important role in marine environments and studying the diversity of these organisms that live associated with the bottom is indispensable for comprehending the environment's functioning. The macrofauna, meiofauna, and microorganisms associated with soft and hard bottom were listed, and additional information, such as the habitat and geographical distribution, were provided for each species. The checklist includes 826 species, almost 70% recorded during the BIOTA/Araçá project. The most speciose taxa were the annelids (225 spp.), mollusks (194 spp.), and crustaceans (177 spp.). Seven benthic species are endemic to Araçá Bay, 14 are considered threatened, and seven are economically exploited. Furthermore, the bay is the type locality of many taxa, and 11 new benthic species were described based on specimens sampled during the project. This project shows the importance of Araçá Bay as a unique biologically rich environment and highlights the need for conservation efforts in light of the current threats.

Resumo O aumento da modificação dos habitats e da perda de espécies demanda esforços consistentes para descrever e compreender os padrões de biodiversidade. O programa BIOTA/FAPESP foi criado nesse contexto e é uma iniciativa de sucesso para promover estudos em biodiversidade e conservação no Brasil. O BIOTA/Araçá é um projeto interdisciplinar que promoveu uma avaliação detalhada da biodiversidade da Baía do Araçá, um ecossistema costeiro localizado ao Norte do estado de São Paulo, Sudeste do Brasil. A baía engloba múltiplos habitats, tais como praias, manguezais, costões rochosos, e uma planície de maré, e também fornece importantes serviços ecossistêmicos. Infelizmente, a baía está sujeita à conflitos sócio-ambientais complexos que contrastam demandas econômicas, sociais e ambientais (i.e. a expansão das atividades do porto vizinho vs. a pesca artesanal de pequena escala e a proteção da biodiversidade). O presente estudo apresenta um levantamento das espécies bentônicas que ocorrem nos diferentes habitats da Baía do Araçá, incluindo dados obtidos durante o projeto BIOTA/Araçá e de investigações realizadas anteriormente na área. As espécies bentônicas desempenham um papel importante no ambiente marinho, e estudar a diversidade desses organismos que vivem associados ao fundo é indispensável para compreender o funcionamento do meio ambiente. A macrofauna, meiofauna, e microorganismos associados aos fundos consolidado e inconsolidado foram listados, e informações adicionais foram fornecidas para cada espécie, tais como a distribuição geográfica e nos habitats. O checklist inclui 826 espécies, quase 70% registradas durante o projeto BIOTA/Araçá. Os taxa mais especiosos foram os anelídeos (225 spp.), moluscos (194 spp.), e crustáceos (177 spp.). Entre as espécies bentônicas listadas, sete são endêmicas da Baía do Araçá, 14 são consideradas ameaçadas de extinção, e sete são exploradas economicamente. A baía é a localidade tipo de vários taxa, e 11 novas espécies bentônicas foram descritas com base em espécimes amostrados durante o projeto. Este projeto mostra a importância da Baía do Araçá como um ambiente de riqueza biológica única e demonstra a necessidade de esforços para a sua conservação considerando as atuais ameaças.

Soil arthropod community responses to restoration in areas impacted by iron mining tailings deposition after Fundão dam failure.

In 2015, the failure of the Fundão dam in Mariana, Brazil released ~43 million m3 of iron mining tailings into the environment. Despite restoration initiatives in the following years, few studies-and most focused on revegetation-have evaluated the effectiveness of the restoration process in areas impacted by the disaster. We aimed to evaluate the responses of the arthropod community in areas impacted by iron mining tailings deposition from the Fundão dam that is in the restoration process. We defined sampling units in the riparian zone of the Gualaxo do Norte River, which is under restoration, and in a native not impacted riparian zone. We collected soil arthropods using pitfall traps and sampled environmental variables in the same sites. We used generalize least squares models (GLS) to test if the restored areas already presented values of arthropod diversity and functional group abundance similar to the reference area and to test which environmental variables are influencing arthropod diversity. We also tested how large the differences of arthropod community composition between the study areas and used the index of indicator species (IndVal) to verify which species could be used as an indicator of reference or restoration areas. The diversity of arthropods and the functional groups of detritivores and omnivores were higher in the native riparian zone. Understory density, soil density, organic matter content, and microbial biomass carbon were the environmental variables that significantly explained the diversity and species composition of arthropods. We show that restoration areas still have different soil arthropod diversity values and community composition when compared to reference areas. Evaluating the response of the arthropod community to the restoration process and long-term monitoring are essential to achieve a satisfactory result in this process and achieve a self-sustaining ecosystem.

Spatial distribution of meiofaunal and macrofaunal assemblages in the tidal flats of the southern Korean coast in relation to natural and anthropogenic impacts.

We investigated the spatial variability of macrofaunal and meiofaunal assemblages in intertidal flats on the southern coast of Korea. Abiotic and biotic samples were collected at five stations. The species richness, density, and composition of the assemblages differed significantly among stations. Nematoda and Annelida were the most dominant meiofaunal and macrofaunal taxa, respectively, although taxon dominance differed among stations. Distance-based linear models showed that sediment-related variables and heavy metals were the main environmental factors determining the spatial variability of the assemblages. Macrofauna had only sediment-related variables and heavy metals as major environmental factors, but meiofauna were also influenced by other environmental factors such as sea surface temperature, dissolved oxygen-related variables, and salinity. This study can provide basic ecological data for understanding the spatial distribution of macro-meiofaunal assemblages and aid in the development of marine environmental management strategies on the western south coast of Korea.

Multi-benthic size approach to unveil different environmental conditions in a Mediterranean harbor area (Ancona, Adriatic Sea, Italy).

Harbors are hubs of human activity and are subject to the continuous discharge and release of industrial, agricultural, and municipal waste and contaminants. Benthic organisms are largely known to reflect environmental conditions they live in. Despite meio- and macrofauna interacting within the benthic system, they are ecologically distinct components of the benthos and as such may not necessarily respond to environmental conditions and/or disturbances in the same way. However, in a few field studies the spatial patterns of meio- and macrofauna have been simultaneously compared. In the present study, we assess the response and patterns in the abundance, diversity, and distribution of the two benthic size classes to the different environmental conditions they live in (i.e., sediment concentrations of selected trace metals and polycyclic aromatic hydrocarbons (PAHs); organic matter contents and grain size) characterizing the Ancona Harbor (Adriatic Sea). Meio- and macrofauna provided partially similar types of information depending on the indices used (univariate measures or community structure/species composition) and the different 'response-to-stress'. The community structure (i.e., taxa composition) of both benthic size components clearly showed differences among sampling stations located from inside to outside the harbor, reflecting the marked environmental heterogeneity and disturbance typically characterizing these systems. Notwithstanding, the univariate measures (i.e., meio- and macrofauna total abundance, diversity indices and equitability) didn't show similar spatial patterns. Meiofauna were likely to be more sensitive to the effects of environmental features and contaminants than macrofauna. Overall, trace metals and PAHs affected the community composition of the two benthic components, but only the meiofauna abundance and diversity were related to the environmental variables considered (i.e., quantity and quality of organic matter). Our results pinpoint the importance of studying both meio- and macrofauna communities, which could provide greater insight into the processes affecting the investigated area and reveal different aspects of the benthic ecosystems in response to harbor conditions.

Responses of biological traits of macrobenthic fauna to a eutrophication gradient in a semi-enclosed bay, China.

The impacts of eutrophication on benthic ecological functions are of increasing concern in recent years. In order to assess the response of macrobenthic fauna to increasing eutrophication, two field sampling surveys were conducted during the summer (July-August 2020) and autumn (October-November 2020) from offshore, nearshore to estuarine sediments in Bohai Bay, northern China. Biological trait analysis was employed for the assessment of macrofaunal samples. The results indicated that there was an increase in the proportion of benthic burrowering or tube-dwelling sediment feeders and taxa with higher larval dispersal ability, but a decrease in the proportion of taxa showing high motility in areas with higher nutrient levels. Seasonal differences were also noted in the shift in biological traits, with a significantly lower similarity among the sampling areas in summer and a higher proportion of carnivorous taxa in autumn. The findings suggested that long-term disturbance can lead to the dominance of smaller body-sized benthic species and reduced sediment quality, impeding ecological recovery of benthic organisms under such harsh environment.