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Ecological interactions among benthic communities are crucial for shaping marine ecosystems. Understanding these interactions is essential for predicting how ecosystems will respond to environmental changes, invasive species, and conservation management. However, determining the prevalence of species interactions at the community scale is challenging. To overcome this challenge, we employ tools from social network analysis, specifically exponential random graph modelling (ERGM). Our approach explores the relationships among animal and plant organisms within their neighbourhoods. Inspired by companion planting in agriculture, we use spatiotemporal co-occurrence as a measure of mixed species interaction. In other words, the variety of community interactions based on co-occurrence defines what we call 'co-occurrence social diversity'. Our objective is to use ERGM to quantify the proportion of interactions at both the simple paired level and the more complex triangle level, enabling us to measure and compare co-occurrence social diversity. Applying our approach to the Spanish coastal zone across eight sites, five depths, and sunlit/shaded aspects, we discover that 80% of sessile communities, consisting of over a hundred species, exhibit co-occurrence social diversity, with 5% of species consistently forming associations with other species. These organism-level interactions probably have a significant impact on the overall character of the site. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.

Current latitudinal diversity gradient (LDG) meta-analyses have failed to distinguish one of the most widespread marine habitats, the intertidal zone, as a separate system despite it having unique abiotic challenges and spatially compressed stress gradients that affect the distribution and abundance of resident species. We address this issue by revisiting published literature and datasets on LDGs since 1911 to explore LDG patterns and their strengths in intertidal benthic, subtidal benthic, and pelagic realms and discuss the importance of recognizing intertidal ecosystems as distinct. Rocky shorelines were the most studied intertidal ecosystem encompassing 64.2% of intertidal LDG studies, and 62.9% of studies focused on assemblage composition, while the remaining 37.1% of studies were taxa specific. While our analyses confirmed LDGs in subtidal benthic and pelagic realms, with a decrease in richness toward the poles, we found no consistent intertidal LDGs in any ocean or coastline across hemispheres or biodiversity unit. Analyzing intertidal and subtidal zones as separate systems increased the strength of subtidal benthic LDGs relative to analyses combining these systems. We demonstrate that in intertidal ecosystems across oceans in both hemispheres, a latitudinal decrease in species richness is not readily apparent, which stands in contrast with significant LDG patterns found in the subtidal realm. Intertidal habitat heterogeneity, regional environmental variability and biological interactions can create species-rich hot spots independent of latitude, which may functionally outweigh a typical latitudinal decline in species richness. Although previous work has shown weaker LDGs in benthic than pelagic systems, we demonstrate that this is caused by combining subtidal and intertidal benthic ecosystems into a single benthic category. Thus, we propose that subtidal and intertidal ecosystems cannot be combined into one entity as the physical and biological parameters controlling ecosystem processes are vastly different, even among intertidal ecosystems. Thus, the intertidal zone offers a unique model system in which hypotheses can be further tested to better understand the complex processes underlying LDGs., (© 2023 The Authors. Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)

Mass extinctions are defined by extinction rates significantly above background levels and have had substantial consequences for the evolution of life. Geographically selective extinctions, subsequent originations and species redistributions may have changed global biogeographical structure, but quantification of this change is lacking. In order to assess quantitatively the biogeographical impact of mass extinctions, we outline time-traceable bioregions for benthic marine species across the Phanerozoic using a compositional network. Mass extinction events are visually recognizable in the geographical depiction of bioregions. The end-Permian extinction stands out with a severe reduction of provinciality. Time series of biogeographical turnover represent a novel aspect of the analysis of mass extinctions, confirming concentration of changes in the geographical distribution of benthic marine life., (© 2018 The Author(s).)

Coastal lagoons are highly productive ecosystems, which are experiencing a variety of human disturbances at increasing frequency. Bacteria are key ecological players within lagoons, yet little is known about the magnitude, patterns and drivers of diversity in these transitional environments. We carried out a seasonal study in the Venice Lagoon (Italy) and the adjacent sea, to simultaneously explore diversity patterns in different domains (pelagic, benthic) and their spatio-temporal variability, and test the role of environmental gradients in structuring assemblages. Community composition differed between lagoon and open sea, and between domains. The dominant phyla varied temporally, with varying trends for the two domains, suggesting different environmental constraints on the assemblages. The percentage of freshwater taxa within the lagoon increased during higher river run-off, pointing at the lagoon as a dynamic mosaic of microbial taxa that generate the metacommunity across the whole hydrological continuum. Seasonality was more important than spatial variability in shaping assemblages. Network analyses indicated more interactions between several genera and environmental variables in the open sea than the lagoon. Our study provides evidences for a temporally dynamic nature of bacterial assemblages in lagoons and suggests that an interplay of seasonally influenced environmental drivers shape assemblages in these vulnerable ecosystems., (© 2017 John Wiley & Sons Ltd.)

In alpine regions worldwide, climate change is dramatically altering ecosystems and affecting biodiversity in many ways. For streams, receding alpine glaciers and snowfields, paired with altered precipitation regimes, are driving shifts in hydrology, species distributions, basal resources, and threatening the very existence of some habitats and biota. Alpine streams harbour substantial species and genetic diversity due to significant habitat insularity and environmental heterogeneity. Climate change is expected to affect alpine stream biodiversity across many levels of biological resolution from micro- to macroscopic organisms and genes to communities. Herein, we describe the current state of alpine stream biology from an organism-focused perspective. We begin by reviewing seven standard and emerging approaches that combine to form the current state of the discipline. We follow with a call for increased synthesis across existing approaches to improve understanding of how these imperiled ecosystems are responding to rapid environmental change. We then take a forward-looking viewpoint on how alpine stream biologists can make better use of existing data sets through temporal comparisons, integrate remote sensing and geographic information system (GIS) technologies, and apply genomic tools to refine knowledge of underlying evolutionary processes. We conclude with comments about the future of biodiversity conservation in alpine streams to confront the daunting challenge of mitigating the effects of rapid environmental change in these sentinel ecosystems., (© 2017 Cambridge Philosophical Society.)

Despite the deep sea being the largest habitat on Earth, there are just 77 population genetic studies of invertebrates (115 species) inhabiting non-chemosynthetic ecosystems on the deep-sea floor (below 200 m depth). We review and synthesize the results of these papers. Studies reveal levels of genetic diversity comparable to shallow-water species. Generally, populations at similar depths were well connected over 100s-1,000s km, but studies that sampled across depth ranges reveal population structure at much smaller scales (100s-1,000s m) consistent with isolation by adaptation across environmental gradients, or the existence of physical barriers to connectivity with depth. Few studies were ocean-wide (under 4%), and 48% were Atlantic-focused. There is strong emphasis on megafauna and commercial species with research into meiofauna, "ecosystem engineers" and other ecologically important species lacking. Only nine papers account for ~50% of the planet's surface (depths below 3,500 m). Just two species were studied below 5,000 m, a quarter of Earth's seafloor. Most studies used single-locus mitochondrial genes revealing a common pattern of non-neutrality, consistent with demographic instability or selective sweeps; similar to deep-sea hydrothermal vent fauna. The absence of a clear difference between vent and non-vent could signify that demographic instability is common in the deep sea, or that selective sweeps render single-locus mitochondrial studies demographically uninformative. The number of population genetics studies to date is miniscule in relation to the size of the deep sea. The paucity of studies constrains meta-analyses where broad inferences about deep-sea ecology could be made., (© 2017 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.)

Little is known about protists at deep-sea hydrothermal vents. The vent sites at Guaymas Basin in the Gulf of California are characterized by dense mats of filamentous pigmented or nonpigmented Beggiatoa that serve as markers of subsurface thermochemical gradients. We constructed 18S rRNA libraries to investigate ciliate assemblages in Beggiatoa mats and from bare sediments at the Guaymas vent site. Results indicated a high diversity of ciliates, with 156 operational taxonomic units identified in 548 sequences. Comparison between mat environments demonstrated that ciliate and bacterial assemblages from pigmented mats, nonpigmented mats, and bare sediments were significantly different and highly correlated with bacterial assemblages. Neither bacterial nor ciliate assemblages were correlated with environmental factors. The most abundant ciliates at Guaymas were more likely to be represented in clone libraries from other hydrothermal, deep-sea, and/or anoxic or microaerophilic environments, supporting the hypothesis that these ciliate species are broadly distributed. The orange mat environment included a higher proportion of ciliate sequences that were more similar to those from other environmental studies than to cultured ciliate species, whereas clone libraries from bare sediments included sequences that were the most highly divergent from all other sequences and may represent species that are endemic to Guaymas., (© 2013 The Author(s) Journal of Eukaryotic Microbiology © 2013 International Society of Protistologists.)

Culture collections such as the Blue Biotechnology and Ecotoxicology Culture Collection (LEGE‐CC) hold approximately 1200 cyanobacterial strains and are critical community resources. However, many isolates in this and other collections have not been described with a polyphasic approach, and this limits further study. Here, we employed a polyphasic methodology that integrates 16S rRNA gene phylogenetic analyses, similarity (p‐distance), 16S‐23S ITS rRNA region secondary structures, morphological analyses, and habitat assessments to describe four novel cyanobacterial genera from the LEGE‐CC, Portugal. Pseudolimnococcus planktonicus gen. et sp. nov. (Chroococcales) is phylogenetically and morphologically related to Limnococcus. The 16S rRNA gene similarity between the types of both genera is only 93.1%. Morphologically, Pseudolimnococcus cells do not reach the original spherical shape before the next division or have aerotopes and firm mucilage, while Limnococcus cells reach the original shape, lack aerotopes, and have diffluent mucilage. Eucapsopsis lusitanus gen. et sp. nov. (Chroococcales) is morphologically similar to Eucapsis but differs from it by having aerotopes and diffluent envelope. Eucapsis lacks aerotopes and has firm mucilaginous envelopes, rarely diffluent. Both genera are phylogenetically very distant from each other and have only 90.68% 16S rRNA gene similarity. Pseudoacaryochloris arrabidensis gen. et sp. nov. (Acaryochloridales) differs from Acaryochloris by the lack of mucilaginous envelope, which is present in Acaryochloris. Both genera are phylogenetically distant and have only 94.1% 16S rRNA gene similarity. Moreover, Acaryochloris is marine (sponge symbiont), while Pseudoacaryochloris is from freshwater. Vasconcelosia minhoensis gen. et sp. nov. (Nodosilineales) is phylogenetically related to Cymatolege but has only 94.3% similarity with this genus. Morphologically both genera are distinct. Vasconcelosia has a Romeria‐like structure, while Cymatolege has a Phormidium‐like structure. In all cases the 16S‐23S ITS rRNA region secondary structures are in agreement with the other analyses. These novel genera expand the diversity of cyanobacteria in culture collections. [ABSTRACT FROM AUTHOR]

Globally, nations are designating marine protected areas to recover and protect habitats and species. With targets to protect 30% of marine areas by 2030, the effectiveness of MPAs to protect designated space is important. In Lyme Bay (south‐west UK), two co‐located MPAs have each adopted different management styles to exclude mobile demersal fishing: a Special Area of Conservation (SAC) protecting the known extent of sensitive reef habitat and an area including a mosaic of reef and sedimentary habitats where the whole site is protected from mobile demersal fishing under a statutory instrument (SI). Underwater videography, both towed (individuals m−2) and baited (MaxN), was used to enumerate change over time of reef species (number of taxa, total abundance, functional richness and functional redundancy) in the MPAs and nearby control areas (2008–2019). Total abundance and functional redundancy of sessile taxa and functional richness of mobile taxa increased, while the number of sessile or mobile taxa, functional richness of sessile taxa, total abundance of mobile taxa or functional redundancy of mobile taxa did not differ from nearby control sites. Over time, both management styles did result in increases in sessile and sedentary taxa diversity relative to open controls, with increases in total abundance of 15% and 95% in the "feature‐based" and whole‐site MPAs, respectively, alongside increases in the number of sessile taxa of 44% over time in the "feature‐based" MPA. However, the mobile taxa in the whole‐site MPA showed levels of functional redundancy 7% higher than the "feature‐based" MPA, indicative of a higher community resilience inside the whole‐site MPA to perturbations, such as storms or biological invasions. Increases seen in the diversity of sessile taxa were expected only in areas where mobile demersal fishing was excluded (~46.8% of its areas). Therefore, if the whole "feature‐based" MPA was consistently protected, we expected to see similar levels of increase in the functional extent of reef. While the "feature‐based" MPA showed similar results over time to that of the "whole site," the "whole site" showed higher levels of diversity, both taxonomical and functional. [ABSTRACT FROM AUTHOR]

Aim: Spatial compositional turnover varies considerably among co‐occurring assemblages of organisms, presumably shaped by common processes related to species traits. We investigated patterns of spatial turnover in a diverse set of marine assemblages using zeta diversity, which extends traditional pairwise measures of turnover to capture the roles of both rare and common species in shaping assemblage turnover. We tested the generality of hypothesized patterns related to ecological traits and provide insights into mechanisms of biodiversity change. Location: Temperate pelagic and benthic marine assemblages of micro‐ and macroorganisms along south‐eastern Australia (30–36° S latitude). Time period: 2008–2021. Major taxa studied Bacteria, phytoplankton, zooplankton, fish, and macrobenthic groups. Methods: Six marine datasets spanning bacteria to fishes were collated for measures of "species" occurrence, with a 1° latitude grain. For each assemblage, ecological traits of body size, habitat and trophic level were analysed for the form and rate of decline in zeta diversity and for the species retention rate. Results: Species at higher trophic levels showed two to three times the rate of zeta diversity decline compared with lower trophic levels, indicating an increase in turnover from phytoplankton to carnivorous fishes. Body size showed the hypothesized unimodal relationship with rates of turnover for macroorganisms. Patterns of bacterial turnover contrasted with those found for macroorganisms, with the highest levels of turnover in pelagic habitats compared with benthic (kelp‐associated) habitats. The shape of retention rate curves showed the importance of both rare and common species in driving turnover; a finding that would not have been observable using pairwise (beta diversity) measures of turnover. Main conclusions Our results support theoretical predictions for phytoplankton and macroorganisms, showing an increase in turnover rate with trophic level, but these predictions did not hold for bacteria. Such deviations from theory need to be investigated further to identify underlying processes that govern microbial assemblage dynamics. [ABSTRACT FROM AUTHOR]

Foraminifera include diverse shell‐building lineages found in a wide array of aquatic habitats from the deep‐sea to intertidal zones to brackish and freshwater ecosystems. Recent estimates of morphological and molecular foraminifera diversity have increased the knowledge of foraminiferal diversity, which is critical as these lineages are used as bioindicators of past and present environmental perturbation. However, a comparative analysis of foraminiferal biodiversity between their major habitats (freshwater, brackish, intertidal, and marine) is underexplored, particularly using molecular tools. Here, we present a metabarcoding survey of foraminiferal diversity across different ecosystems using newly designed foraminifera‐specific primers that target the hypervariable regions of the foraminifera SSU‐rRNA gene (~250–300 bp long). We tested these primer sets on four foraminifera species and then across several environments: the intertidal zone, coastal ecosystems, and freshwater vernal pools. We retrieved 655 operational taxonomic units (OTUs); the majority of which are undetermined taxa that have no closely matching sequences in the reference database. Furthermore, we identified 163 OTUs with distinct habitat preferences. Most of the observed OTUs belonged to lineages of single‐chambered foraminifera, including poorly explored freshwater foraminifera which encompass a clade of Reticulomyxa‐like forms. Our pilot study provides the community with an additional set of newly designed and taxon‐specific primers to elucidate foraminiferal diversity across different habitats. [ABSTRACT FROM AUTHOR]

We investigated the use of eDNA metabarcoding for supplementing traditional diver-based monitoring of biodiversity of marine boulder reefs within the photic zone. The applied sampling design made it possible to evaluate the usefulness of eDNA monitoring as a supplement for traditional monitoring. Specifically, this study aimed to (1) assess the local influence of boulder reefs on biodiversity across the North Sea to Baltic Sea transition zone and (2) investigate the importance of environmental gradients for patterns in community structure. On samples collected during August 2020, we compared the composition and abundance of species associated with nine reefs, representing an environmental gradient of salinity (16–33 psu), water temperature (16–21°C) and water depth (6–29 m). At each reef site, water was sampled near the bottom just above the reef and on average 2.6 km upstream and downstream (location) and sequenced with metabarcoding using COI, 18S and 12S rDNA primers. eDNA identified 400 species, diver-based observations identified 184 with an overlap of 70 species (12%) and 81 genera (18%). While eDNA identified many infaunal species, it did not detect several macroalgal species which dominated in the diver-based observations. Multivariate analysis of eDNA and diver-based community structure both distinguished between reef communities, with a significant match between patterns observed by the two methods (r = 0.37, p = 0.02). Furthermore, the eDNA approach made it possible to identify significant differences in species composition between upstream, above-reef and downstream locations, suggesting that eDNA leaves a local footprint in benthic habitats. Patterns in both eDNA and diver-based species composition and richness were significantly related to geographical distance, salinity, water temperature and water depth. Despite of low detection of macroalgae, the eDNA sampling provided a substantial supplement to traditional diver-based monitoring of biodiversity around benthic hotspots in the Danish marine waters and therefore we recommend to add eDNA methods to conventional monitoring programs in the future.

Thirty-seven holothuroid species, including six potentially new, are reported from the eastern Weddell Sea in Antarctica. Information regarding sea cucumbers in this dataset is based on Agassiz Trawl (AGT) samples collected during the British Antarctic Survey cruise JR275 on the RRS James Clark Ross in the austral summer of 2012. Species presence by site and an appendix of holothuroid identifications with registrations are included as supplementary material. Species occurrence in the Weddell Sea is updated to include new holothuroids from this expedition. [ABSTRACT FROM AUTHOR]

The waters around Iceland, bounding the Northern North Atlantic and the Nordic seas, are a region characterized by complex hydrography and seabed topography. This and the presence of the Greenland-Iceland-Faroe-Scotland ridge (GIFR) are likely to have a major impact on the diversity and distribution of the benthic fauna there. Biodiversity in this region is also under increasing threat from climate-induced changes, ocean warming and acidification in particular, affecting the marine realm. The aim of the present study was to investigate the biodiversity and distributional patterns of amphipod crustaceans in Icelandic waters and how it relates to environmental variables and depth. A comprehensive data set from the literature and recent expeditions was compiled constituting distributional records for 355 amphipod species across a major depth gradient (18–3,700 m). Using a 1o hexagonal grid to map amphipod distributions and a set of environmental factors (depth, pH, phytobiomass, velocity, dissolved oxygen, dissolved iron, salinity and temperature) we could identify four distinct amphipod assemblages: A Deep-North, Deep-South, and a Coastal cluster as well as one restricted to the GIFR. In addition to depth, salinity and temperature were the main parameters that determined the distribution of amphipods. Diversity differed greatly between the depth clusters and was significantly higher in coastal and GIFR assemblages compared to the deep-sea clusters north and south of the GIFR. A variety of factors and processes are likely to be responsible for the perceived biodiversity patterns, which, however, appear to vary according to region and depth. Low diversity of amphipod communities in the Nordic basins can be interpreted as a reflection of the prevailing harsh environmental conditions in combination with a barrier effect of the GIFR. By contrast, low diversity of the deep North Atlantic assemblages might be linked to the variable nature of the oceanographic environment in the region over multiple spatio-temporal scales. Overall, our study highlights the importance of amphipods as a constituent part of Icelandic benthos. The strong responses of amphipod communities to certain water. mass variables raise the question of whether and how their distribution will change due to climate alteration, which should be a focus of future studies. [ABSTRACT FROM AUTHOR]

Aim: Topographic complexity is widely accepted as a key driver of biodiversity, but at the patch‐scale, complexity–biodiversity relationships may vary spatially and temporally according to the environmental stressors complexity mitigates, and the species richness and identity of potential colonists. Using a manipulative experiment, we assessed spatial variation in patch‐scale effects of complexity on intertidal biodiversity. Location: 27 sites within 14 estuaries/bays distributed globally. Time period: 2015–2017. Major taxa studied: Functional groups of algae, sessile and mobile invertebrates. Methods: Concrete tiles of differing complexity (flat; 2.5‐cm or 5‐cm complex) were affixed at low–high intertidal elevation on coastal defence structures, and the richness and abundance of the colonizing taxa were quantified after 12 months. Results: The patch‐scale effects of complexity varied spatially and among functional groups. Complexity had neutral to positive effects on total, invertebrate and algal taxa richness, and invertebrate abundances. However, effects on the abundance of algae ranged from positive to negative, depending on location and functional group. The tidal elevation at which tiles were placed accounted for some variation. The total and invertebrate richness were greater at low or mid than at high intertidal elevations. Latitude was also an important source of spatial variation, with the effects of complexity on total richness and mobile mollusc abundance greatest at lower latitudes, whilst the cover of sessile invertebrates and sessile molluscs responded most strongly to complexity at higher latitudes. Conclusions: After 12 months, patch‐scale relationships between biodiversity and habitat complexity were not universally positive. Instead, the relationship varied among functional groups and according to local abiotic and biotic conditions. This result challenges the assumption that effects of complexity on biodiversity are universally positive. The variable effect of complexity has ramifications for community and applied ecology, including eco‐engineering and restoration that seek to bolster biodiversity through the addition of complexity. [ABSTRACT FROM AUTHOR]

A recent study of the meiofauna from several intertidal sites along the coast of Chile yielded several gastrotrich specimens. The number of specimens was too small to assess the ecology of the individual species; however, as there are no published records of Gastrotricha in Chile until recently, it is important to document the presence of this group in order to stimulate further research. We report specimens of the genera Lepidodasys, Cephalodasys, Macrodasys, Tetranchyroderma, Xenotrichula and several morphotypes of Turbanella. Additionally, we provide some initial data on the population density of Lepidodasys sp. at Coihuin (Puerto Montt) and an observation of them feeding on nematodes. [ABSTRACT FROM AUTHOR]

Background Attention to the deep-sea environment has increased dramatically in the last decade due to the rising interest in natural resource exploitation. Although Colombia holds a large submerged territory, knowledge of the seabed and its biodiversity beyond 1,000 m depth is very limited. During 2015-2017, Anadarko Colombia Company (ACC) carried out hydrocarbon exploratory activities in the South-western Colombian Caribbean, at depths between 375 m and 2,565 m. New information Capitalising on available data resources from these activities, several cnidarian species were observed in ROV and towed camera surveys. We analysed over nine hours of video and 5,066 still images from these surveys, identifying organisms to the lowest possible taxonomic level. The images and associated data presented here correspond to 108 observations of deep-sea cnidarians, including seven new records for the Colombian Caribbean. Given the paucity of research and funding to explore the deep-sea in Colombia, the present dataset comprises the largest deep-sea Cnidaria imagery inventory to date for the Colombian Caribbean. [ABSTRACT FROM AUTHOR]

SUMMARY A new species of marine sand‐dwelling dinoflagellate, Plagiodinium ballux N. Yamada, Dawut, R. Terada & T. Horiguchi is described from a deep (36 m) seafloor off Takeshima Island, Kagoshima Prefecture, Japan in the subtropical region of the northwest Pacific. The species is thecate and superficially resembles species of Prorocentrum, but possesses an extremely small epitheca. The cell varies from ovoid to a rounded square, and is small (15.0–22.5 μm in length) and laterally compressed. The thecal plates are smooth and the thecal plate arrangement (Po, 1′, 0a, 5″, 5C, 2S, 5‴, 0p, 1″″) is similar to that of Plagiodinium belizeanum, the type species of the genus. Molecular phylogenetic analyses based on SSU rDNA and partial LSU rDNA reveal that the dinoflagellate is closely related to P. belizeanum, but it can be clearly distinguished by its size and cell shape. This suite of morphological and molecular differences leads to the conclusion that this deep benthic dinoflagellate represents a new species of the genus Plagiodinium. [ABSTRACT FROM AUTHOR]

Abstract Surficial assemblages of mollusk shells provide minimally invasive, quantitative data that are potentially adequate for assessing spatial organization of local benthic ecosystems. This study evaluates distribution and ecological characteristics of mollusk-dominated benthic communities around San Salvador Island (Bahamas). A total of 60 bulk samples collected along 12 onshore-offshore transects around the island yielded 20,301 specimens representing 180 mollusk species. Radiocarbon dating of individual shells (n = 30) indicated that these surficial accumulations represented a multi-millennial (time-averaged) record of local communities. Indirect multivariate ordinations (NMDS) separated mollusk death assemblage samples by locality, local habitat types, and regional context. Even in the case of comparable habitats within the same bay, samples clustered by transect location suggesting that surficial shell accumulations faithfully archive local differences in mollusk communities despite time-averaging and post-mortem shell transport. At the regional scale, a clear faunal separation is observed between windward and leeward sides of the island, suggesting that water energy represents an overriding regional driver that controls local composition of mollusk assemblages. Within each water energy regime, the faunal composition appeared to be primarily controlled by habitat type (seagrass versus sand habitats). Moreover, consistent with theoretical predictions that structured habitats enhance faunal stability of local communities, death assemblages from seagrass habitats were less variable in faunal composition than open sand habitats. Results indicate that San Salvador Island benthic communities are characterized by a predictable spatial organization controlled primarily by regional physical and, secondarily, biological processes. Also, the fact that extensively time-averaged shell assemblages have retained an interpretable spatial pattern suggests that regional physical processes, local habitat distribution, and structuring of mollusk associations must have been stable over multi-centennial time scales. This case study suggests that non-invasive sampling of dead mollusks can be an effective strategy for assessing prevalent long-term patterns in spatial distribution of regional faunal associations and examining processes that drive spatial structuring of marine communities. [ABSTRACT FROM AUTHOR]

Abstract There is increasing interest in finding new, more efficient methods for routine monitoring of anthropogenic effects on benthic biodiversity and ecosystems. A range of molecular methods have been developed for assessing biodiversity the last decades. Particularly interesting are microarrays targeting phylogenetic marker genes, such as the small subunit of ribosomal RNA in eukaryotes (18S rRNA). This method can detect a large number of taxonomic groups in several samples simultaneously within a relatively short time and has the potential for incorporation in automated remote sensing pipelines. In this study we developed and tested a microarray for eukaryotes in marine sediments. The probes were designed to target 18S rRNA OTUs obtained through metabarcoding of marine sediments. The resulting microarray was tested using both a spiked sample consisting of 50 plasmid-clones and further, samples of genomic DNA extracted from marine sediments. We developed a filtration pipeline to eliminate noise and reduce the number of false positives, making it possible to detect and quantify most of the OTUs with ≥ 0.1% abundance in the spiked sample. Our data indicated that the microarray was specific at higher taxonomic levels. However, the specificity decreased with increasing sequence similarity suggesting cross-hybridization between closely related OTUs. When using genomic DNA isolated from marine sediment there was a positive correlation between hybridization intensity signals and abundance of sequencing reads, suggesting a quantitative behavior of the microarray. Overall, the data suggest a potential for microarrays as a tool for high throughput sediment monitoring. Highlights • Development of a microarray targeting eukaryotic taxonomic groups. • Separation between related taxonomic groups using the microarray. • Quantitative capacity of genetic fragments from a spiked sample. • Evaluating the microarray with 18S rRNA amplicons obtained from marine sediment. • Suggest microarray method development for environmental monitoring. [ABSTRACT FROM AUTHOR]

Flows of energy and matter across habitat boundaries can be major determinants of the functioning of recipient ecosystems. It is currently debated whether terrestrial dissolved organic matter (tDOM) is a resource subsidy or a resource subtraction in recipient lakes. We present data from a long-term field experiment in which pelagic phosphorus concentration and whole-ecosystem primary production increased with increasing tDOM input, suggesting that tDOM acted primarily as a direct nutrient subsidy. Piecewise structural equation modeling supports, however, a substantial contribution of a second mechanism: colored tDOM acted also as a resource subtraction by shading benthic algae, preventing them from intercepting nutrients released across the sediment-water interface. Inhibition of benthic algae by colored tDOM thus indirectly promoted pelagic algae and whole-ecosystem primary production. We conclude that cross-ecosystem terrestrial DOM inputs can modify light and nutrient flows between aquatic habitats and alter the relative contributions of benthic and pelagic habitats to total primary production. These results are particularly relevant for shallow northern lakes, which are projected to receive increased tDOM runoff. [ABSTRACT FROM AUTHOR]

Benthic macro invertebrates represent a useful tool in the evaluation of environmental quality through studies of the structure of communities and their relationship to anthropic activities within a reservoir. The objective of this study was to assess diversity of some benthic macro invertebrates in Ajiwa reservoir. The study was carried out from September, 2014 to August, 2015. Benthic macro invertebrate samples were collected with the aid ofEkman grab at 5 different sampling locations once monthly. Samples collected were sieved with a set of Tyler sieves of 20cm diameter and mesh sizes of 2mm, 1mm, and 150μm respectively and transferred into labelled plastic storage bottle and preserved with 4% formalin prior to sorting and identification with the aid of some keys. Twenty four (24) taxa from a total of 1420 individual’s organisms were recorded. These include 5 species each of Mollusca and Diptera, 1 species of Odonata, 4 species of Hemiptera and 3 species each of Coleoptera, Oligochaete and Nematoda. The relative percentage composition of the major taxonomic groups to the overall macro benthic population at the different stations revealed that the study area was inhabited by Oligochaete (40.28%), Molluscs (24.08%), Diptera (19.29%), Odonata (5.78%), Coleoptera (3.94%), Nematodes (3.38%) and Hemiptera (3.24%).The indices of general diversity (H), evenness (E), dominance and relative abundance were in the following order of increasing magnitude: station 5 > station 1 > station 4 > station 2 and > station 3 respectively. Factors which influenced the abundance and distribution of invertebrates; including the nature of the water body, habitat richness and stability, immediate substrate, tropic condition, resource partitioning and predation coupled with habitat differences observed in this study, acted singly or in combination to influence the variation in abundance of benthic macro invertebrate of Ajiwa Reservoir.

Although the Erfelek Stream is a small stream with a total length of 80 km and a flood discharge of 302.1 m3/sec, from its source to the place where it merges with the sea. It is ecologically very important for its immediate environment in terms of the zonations created by it and the groups of living organisms it contains. The fact that it is the only stream that reaches the sea by forming a delta between the Kızılırmak and Filyos Stream and that it reaches the sea by drawing meanders in the delta after different geological formations it passes through starting from an altitude of 1370 meters allows it to be a stream rich in biodiversity. Karagöl, which is connected with the sea, which is almost destroyed within the delta, and the Aksaz wetlands, which are still continuing their existence increase the importance of the stream in terms of both aquatic products and other groups of living organisms. In the fauna and flora of the Erfelek stream, the presence e few benthic invertebrate, fish, birds, mammals and plant species have been identified up to now. On this study, the importance of biodiversity and ecology of Erfelek Stream is aimed to be revealed as a result of present data and preliminary observations. [ABSTRACT FROM AUTHOR]

O presente trabalho teve como objetivo principal verificar a biodiversidade bentônica em áreas do fundo da lagoa do Coqueiral, zona de desembocadura do rio Paranapanema, na represa de Jurumirim, Estado de São Paulo. Foram selecionados dezoito pontos de amostragem, englobando áreas rasas e áreas profundas. As coletas foram feitas emintervalos trimestrais ao longo de um ano; também foram analisadas as variáveis físicas e químicas da água (nível, transparência, temperatura, oxigênio dissolvido, pH e condutividade elétrica). Amostras do sedimento, para análise da fauna e de fatores abióticos(granulometria e conteúdo orgânico), foram recolhidas em tréplicas, utilizando como coletor a draga de Petersen. O material foi triado e analisado sob microscópio estereoscópico. Contagem e identificação dos organismos foram realizadas, e densidade, abundância relativa, riqueza taxonômica e índice de dominância foram calculados. A análiserevelou uma fauna com baixa diversidade e a dominância de Chironomidae e Ephemeroptera. Domínio de Ephemeroptera, constituído por Campsurus, ocorreu no período mais quente do ano e com baixa profundidade da lagoa. A distribuição dos organismos teve como principais fatores determinantes profundidade, transparência, pH etemperatura da água. Na comparação feita entre áreas rasas e profundas, foi observada uma menor densidade de organismos nas regiões profundas.Coqueiral lake is a marginal lake located at the southeast São Paulo State, in the mouth zone of the Paranapanema river into Jurumirim Reservoir and it has high connectivity with the Paranapanema river. This work aimed to verify the benthic biodiversity in areas of the lake bottom. 18 sampling sites in the lake were selected, including shallow and deep areas. The samples were taken every three months during one year. Physical and chemical water variables (level, transparency, dissolved oxygen, pH, and electric conductivity) were analyzed. Sediment samples were picked up in triplicate for fauna and abiotic factors analysis (granulometric composition and sediment organic content), using Petersen dredge. The material was sorted out and analyzed under stereoscopic microscope. Counting and identification of the organisms were accomplished and diversity, relative abundance, taxonomic richness and dominance index were calculated. The analysis revealed a fauna with low species diversity and, with Chironomidae and Ephemeroptera dominance. Ephemeroptera, Campsurus, dominated in the hottest period and with low lake depth. Organisms’ distribution had as main factors depth, transparency, pH, and water temperature. In the comparison between shallow and deep areas, a small density of organism in the deep regions was observed.

This introductory paper lays the basis for this supplementary issue by briefly presenting the state of knowledge on the KwaZulu-Natal (KZN) Bight at the start of this multi-disciplinary, multi-institutional, ship-based research project that ran from 2009 to 2013. The rationale and aims of the project are also described. The project was a major component of the South African Department of Science and Technology’s African Coelacanth Ecosystem Programme (ACEP), which has been prominent in supporting research on the east coast of South Africa and the wider South-West Indian Ocean. Pivotal to this was the RS Algoa, which was made available for two 30-day surveys (winter and summer) in the KZN Bight by the Department of Environmental Affairs. Although some aspects of the bight ecology are known, much of the research is dated and fragmented, and required refreshing and consolidation in order to produce a platform upon which the understanding of the region’s ecosystem functioning could be established. Much of the oceanographic knowledge is also dated, with no dedicated surveys and significant measurements undertaken since 1989. The overarching theme of the KZN Bight project was to examine the relative importance of sources of nutrients to the central KZN coast and how these are taken up and recycled in the ecosystem, and to describe aspects of the benthic biodiversity, which is poorly described in much of this region. An ambitious project, its accessibility to a ship-based research platform and the diverse scientific skills of the participating scientists allowed considerable success, as reflected in the papers that follow. [ABSTRACT FROM AUTHOR]

This introductory paper lays the basis for this supplementary issue by briefly presenting the state of knowledge on the KwaZulu-Natal (KZN) Bight at the start of this multi-disciplinary, multi-institutional, ship-based research project that ran from 2009 to 2013. The rationale and aims of the project are also described. The project was a major component of the South African Department of Science and Technology’s African Coelacanth Ecosystem Programme (ACEP), which has been prominent in supporting research on the east coast of South Africa and the wider South-West Indian Ocean. Pivotal to this was the RS Algoa, which was made available for two 30-day surveys (winter and summer) in the KZN Bight by the Department of Environmental Affairs. Although some aspects of the bight ecology are known, much of the research is dated and fragmented, and required refreshing and consolidation in order to produce a platform upon which the understanding of the region’s ecosystem functioning could be established. Much of the oceanographic knowledge is also dated, with no dedicated surveys and significant measurements undertaken since 1989. The overarching theme of the KZN Bight project was to examine the relative importance of sources of nutrients to the central KZN coast and how these are taken up and recycled in the ecosystem, and to describe aspects of the benthic biodiversity, which is poorly described in much of this region. An ambitious project, its accessibility to a ship-based research platform and the diverse scientific skills of the participating scientists allowed considerable success, as reflected in the papers that follow. [ABSTRACT FROM AUTHOR]

1. High elevation ecosystems are predicted to be strongly impacted by climate change; however, little is known of extant biodiversity in mountain streams. For this study, five streams in Grand Teton National Park, Wyoming were sampled along a longitudinal gradient to establish a baseline of invertebrate assemblages and environmental conditions. Five Surber samples were collected from low, middle and high elevation sites along each stream. 2. Nearly 10 000 ind m-2 lived in these streams on average, but the density (mixed effects model, P = 0.54) and richness (P = 0.18) of invertebrates did not vary significantly by elevation. Total density of invertebrates was positively related to the amount of visible biofilm (ANOVA, P = 0.03) and oxidation-reduction potential (P = 0.05) and taxa richness was negatively related to specific conductivity (P = 0.009). 3. Invertebrate assemblages and environmental conditions were more similar at low versus high sites when compared using non-metric multidimensional scaling and tests of multivariate dispersion indicating that higher elevation sites harboured more environmental and species diversity. 4. These results can help target which aquatic invertebrates to monitor as stream temperatures rise, and highlight the biotic and abiotic factors that structure aquatic ecosystems in the Teton Range of Grand Teton National Park. [ABSTRACT FROM AUTHOR]

Canopy-forming macroalgae create a specific surrounding habitat (the matrix) with their own ecological properties. Previous studies have shown a wide range of responses to canopy removal. Magnitude and strength of the effects of harvesting are thought to be context-dependent, with the macroalgal matrix that can either soften or exacerbate the impact of harvesting. We experimentally examined in situ the effect of harvesting on targeted commercial species, and how these potential impacts might vary in relation to its associated matrix. We found that patterns of recovery following the harvesting disturbance were variable and matrix specific, suggesting that local factors and surrounding habitat characteristics mediated the influence of harvesting. The greatest and longest effects of harvesting were observed for the targeted species that created a dominant and monospecific canopy on their site prior to the disturbance. Another relevant finding was the important natural spatiotemporal variability of macrobenthic assemblages associated with canopy-forming species, which raises concern about the ability to discriminate the natural variability from the disturbance impact. Finally, our results support the need to implement ecosystem-based management, assessing both the habitat conditions and ecological roles of targeted commercial species, in order to insure the sustainability of the resource. The effects of canopy removal on macrobenthic communities from rocky shores were examined, taking into account the matrix associated to the harvested canopy-forming macroalgae. The greatest effects of harvesting were observed for the species that created a dominant monospecific canopy prior to the disturbance. The results demonstrate the importance of implementing ecosystem-based management, assessing both the habitats conditions and ecological roles of targeted commercial species. [ABSTRACT FROM AUTHOR]

The biological diversity of the Chilean marine ecosystem (CME) has recently become an issue of interest to Chilean scientists and authorities concerned about the impact of human activities and ongoing climate change on the structure, functioning, and sustainable use of this large marine region, recognized as one of the most productive ecosystems of the world`s is oceans. In this paper, the available information is examined in order to describe the major environmental characteristics of the CME and its associated flora and fauna, both in the benthic and pelagic systems, with the main goal of identifying environmental discontinuities and boundaries which may serve to define biogeographical units and characterize their biodiversity patterns. Physical and chemical processes are also described. In the pelagic system, three major regions may be identified: (1) the Northern Upwelling Region (18º-30º S), (2) the Central/Southern Upwelling Region (30º-42º S), and (3) the Austral Fjords Region (42º_55ºS). These could be defined as biogeographical units, though biodiversity patterns may still require further analyses. For the benthic system, two major provinces are distinguished: the Peru-Chile province (from Paita in Peru to Valparaíso in Chile) and the Magellanic province (Chiloé Island to Cape Horn). A clear transition zone at about 30ºS has also been described. The limits of these biogeographical regions, however, are not fixed and may vary seasonally and interannually. Diversity patterns, as well as dominant and key species inhabiting these biogeographic compartments, are described on the basis of the available data. The studies now required to obtain better information to describe diversity and to identify the underlying processes are stressed, as well as the needs for initiating large scale and long-term programs for monitoring species and processes in the CME that may allow future analyses of diversity patterns along the Chilean coast for conservation purposes.La diversidad biológica del ecosistema marino de Chile (CME) es un tema de alto interés para los científicos y autoridades de Chile, dada la actual preocupación por el impacto que las actividades humanas y los cambios climáticos pudieran tener sobre la estructura, funcionamiento y sustentabilidad de la productividad de esta gran región marina, reconocida como una de las más productivas del océano mundial. En el presente trabajo hemos examinado la información disponible con el objeto de describir las características ambientales más importantes del CME, así como su flora y fauna, tanto en el sistema bentónico como pelágico, con una meta esencial dirigida a la identificación de discontinuidades y barreras ambientales, las cuales pueden servir para definir unidades biogeográficas, y así caracterizar patrones de biodiversidad. Los principales procesos físicos y químicos también son descritos. En el sistema pelágico identificamos tres regiones mayores: (1) La región norte de surgencia (18º-30º S), (2) La región centro/sur de surgencia (30º-42º S), y (3) La región austral de fiordos (42º_55ºS). Estas regiones podrían ser definidas como unidades biogeográficas, aunque sus patrones de biodiversidad pueden aún necesitar análisis adicionales. Para el sistema bentónico dos provincias mayores son distinguibles: la provincia Perú-Chile (desde Paita en Perú a Valparaíso en Chile), y la provincia Magallánica (Isla de Chiloé a Cabo de Hornos). Una clara zona de transición alrededor de los 30º S también ha descrito. Los límites de estas regiones biogeográficas no son sin embargo fijos, y pueden variar estacionalmente y entre años. Los patrones de diversidad, así como las especies dominantes y claves que habitan estos compartimentos biogeográficos son descritos sobre la base de datos disponibles. Los estudios necesarios para obtener información más robusta para describir la diversidad y los procesos que la sustentan son enfatizados, así como la necesidad de iniciar programas de monitoreo y procesos en el CME de gran escala y largo término, que puedan permitir futuros análisis de patrones de biodiversidad a lo largo de la costa chilena para propósitos de conservación

Ecuador has a high diversity of ecosystems in its coastal and marine territory with beaches, bays, estuaries, cliffs, coastal lagoons and rocky coasts being the most representative. So far, 1,859 marine species have been identified in Ecuador. Of these, 1380 species of non-commercial marine invertebrates and vertebrates, belonging to 8 Phyla and distributed in 25 groups or classes, occur along the coast of Ecuador. These are: Protozoans, 9 groups: Oceanic and estuarine Diatoms, Cyanophyta, Chlorophyta, Dinoflagellates, Coccolithophorida, Silicoflagellates, Euglenophyta, Tintinnids and planktonic and benthic Foraminifera; Cnidaria, 2 classes: Hydromedusae and Scyphomedusae; Mollusca, 5 classes: Wood-boring molluscs and rock-boring and benthic bivalves; Gasteropoda: (Thecosomatans, Pteropods, Heteropods and benthic species, Polyplacophora, Scaphopoda and Cephalopoda); Annelida, 1 group: benthic Polychaeta; Arthropoda, 1 class: Crustacea (Cirripedia, Anomura, Brachyuran, Euphausiids); Chaetognatha, 1 group; Echinodermata, 4 classes: Asteroidea, Ophiuroidea, Echinoidea and Holothuroidea; Chordata, 2 classes: Marine mammals and birds. Both the biodiversity of the meiobenthos of the Gulf of Guayaquil and that of the inter-tidal zone are presented. The 479 demersal species of commercial importance are grouped in 4 Phyla (Chordata, Arthropoda, Mollusca, and Echinodermata), 41 orders, 143 families and 258 genera. The phylum Chordata represented by fish is the most diverse group on the coast with 270 species from 142 genera, 63 families, and 22 orders, the order Perciformes being the best represented with 143 species. Molluscs form the next biggest group with 110 species. In general, the biggest biodiversity of species seems to be in the Gulf of Guayaquil, the main estuary of Ecuador. However, this may be because that area has been better studied than the others. The work presented is mainly the result of research carried out by Equatorians and thus cannot be claimed to include the whole of the current information about marine biodiversity in Ecuador.Ecuador tiene una diversidad alta de ecosistemas en todo su territorio marino-costero donde las playas, bahías, estuarios, acantilados, lagunas costeras y las costas rocosas son los de mayor representatividad. Hay un total de 1.859 especies marinas que han sido identificadas para Ecuador, que incluye especies comerciales y no comerciales. Se conoce que 1.380 especies de invertebrados y vertebrados marinos no comerciales pertenecen a 8 Phyla, los cuales han sido reportados para el Pacífico ecuatoriano, distribuidos en 25 grupos o clases de organismos que son: Protozoos: 9 grupos: Diatomeas oceánicas y estuarinas, Cyanophyta, Chlorophytas, Dinoflagelados, Coccolitophorida, Silicoflagelados, Euglenophyta, Tintinnidos, Foraminíferos planctónicos y bentónicos, Cnidaria, 2 clases: Hydromedusas y Scyphomedusas; Mollusca, 5 clases: Bivalvos (Bentónicos, perforadores de maderas y rocas), Gasteropods (Pterópodos, Thecosomados y Heterópodos), Poliplacophora, Scaphopoda y Cephalopoda; Annelida, 1 grupo: Poliquetos bentónicos; Arthropoda, 1 clase: Crustacea: (Cirripedia, Anomura, Brachyuran, Euphausiacea); Chaetognatha, 1 grupo; Echinodermata, 4 clases: Asteroidea, Ophiuroidea, Echinoidea y Holothuroidea; Chordata, 2 clases: Mamíferos y aves. Las 479 especies demersales registradas se agruparon en cuatro Phylum (Chordata, Arthropoda, Mollusca y Echinodermata): 258 géneros, 143 familias y 41 órdenes. El Phylum (Chordata) representado por los peces es el grupo más diverso en la costa con 270 especies, agrupadas en 142 géneros, 63 familias y 22 órdenes, siendo el órden Perciformes el más representativo con 143 especie. El registro de 479 especies para cuatro subáreas permitió determinar la presencia de cada especie, así como el de los géneros, familias, y órdenes para el phylum en cada subárea. De los cuatro phyla considerados en este estudio, los peces y los moluscos corresponden a los grupos mejor representados en la costa del Ecuador, con una riqueza de 270 y 110 especies, respectivamente. En general la biodiversidad más grande de especies se encuentra en el Golfo de Guayaquil, el estuario principal del Ecuador. Sin embargo es necesario indicar que este ecosistema ha sido el más estudiado en relación con los otros, razón por la que, probablemente, subestime a los otros ecosistemas.

Loss of biodiversity and nutrient enrichment are two of the most pervasive drivers of change in ecosystems globally. However, little is known about how these disturbances interact to affect ecosystem functioning., We established a field experiment to test for effects of loss of consumer species on algal assemblages (richness and assemblage structure) and ecosystem functioning (ecosystem productivity and algal biomass accumulation) on rocky shores. We manipulated the presence of three common molluscan grazer species in newly created rock pools over 13 months. Our grazer manipulation was based on a subtractive experimental design, and we also manipulated nutrient concentrations to evaluate explicitly how resource availability affected the consequences of species loss., We found that the effects of loss of grazer species on algal assemblages and their functioning depended strongly on both the identity of the grazer species lost and of those remaining in the community. Moreover, the effects of loss of species depended on nutrient availability, making it extremely difficult to predict the effects of species loss generally without detailed knowledge of a system., Our results demonstrate clearly that the effects of grazer species loss on primary producers and ecosystem functioning may not be generalisable based on grazer functional roles or traits., Synthesis. Our findings highlight the need to include key physical drivers, such as nutrient availability, explicitly into biodiversity-ecosystem functioning models in order to move towards a predictive framework that incorporates the effects of both environmental heterogeneity and anthropogenic stressors. [ABSTRACT FROM AUTHOR]

Abstract: Trophic paths between species are a useful tool for analysing the impact of species invasions of a biotic community. Species invasions produce changes at trophic level and diversity shifts by replacing native species with species of similar ecological niche. This study focused on the effects of macroalgal invasions on seagrass ecosystems. We conducted two – year bimonthly sampling of a pristine Posidonia oceanica seagrass meadow and dead matte colonized by three Caulerpa species bimonthly. The largest changes in faunal composition were found in meadows colonized by Caulerpa prolifera, where major differences in infaunal taxonomic distinctness were apparent. On the other hand, the infaunal community was quite similar between the two invasive Caulerpa species (Caulerpa taxifolia and Caulerpa racemosa). The isotopic niche based on the main trophic guilds established using stable isotope signatures at community level resulted in a highly compacted and 15N-enriched C. prolifera food web structure, indicating high overlap of food source utilization among faunal components, which is typical of degraded systems. Conversely, the P. oceanica ecosystem presented the most complex food web, while the influence of the 2 invasive species were similar. An attempt to reconstruct the food web at each vegetated habitat revealed high trophic linkages among the different trophic levels with a continuous transition among them by the various trophic guilds suggesting an adaptation response of the different organisms to the new habitat forming species. [Copyright &y& Elsevier]

Plant species composition is changing across many landscapes, but it is unclear how these changes affect habitat quality for animals. We used functional diversity and community-weighted mean (CWM) trait values for four plant traits (litter N, P, lignin and soluble phenolics) to explore how changes in plant species composition may affect larval amphibians in a simplified aquatic ecosystem. We predicted that increased functional diversity would improve amphibian performance (survivorship, developmental rate, and size). We also predicted that increases in CWM N and P would improve amphibian performance, while increases in CWM lignin and soluble phenolics would have negative effects on amphibian performance. We did not detect an effect of functional diversity; instead, CWM litter N and soluble phenolics were useful predictors of amphibian performance. We demonstrate that quantifying the CWM of ecologically relevant traits represents a powerful approach for predicting how changes in plant species composition can affect aquatic communities. [ABSTRACT FROM AUTHOR]

In the northwestern Gulf of Mexico, beds of rhodoliths and unconsolidated rubble at 55-70 m depth are associated with unique offshore deep bank habitats known as salt domes or diapirs. Prior to the 2010 BP Deepwater Horizon oil spill these harbored the highest known seaweed diversity in the northern Gulf of Mexico. Six post-spill cruises led offshore Louisiana to two sites previously documented with rich algal assemblages ( i.e. prespill) revealed a dramatic post-spill die-off of seaweeds at both sites, with dredged rhodoliths appearing bleached and mostly denuded of fleshy algae, or 'bare' (with a few crustose genera only, e.g. Corallinales and Peyssonneliales). This rubble, brought to the laboratory and maintained in a series of ∼75 liter microcosm tanks, gradually became covered by a suite of red, green and brown seaweed germlings that to this day continue to grow to adult size, reproduce, disappear and re-emerge, and whose species composition reflects pre-spill assemblages. These experiments revealed the expression of biodiversity from alternative life stages or resting stages apparently repressed in the Gulf at the time of sampling, including new, previously overlooked diversity. The rate of algal succession was documented by biweekly photography, and species taxonomic identity is being confirmed by ongoing molecular and morphological evidence. The implications of these exciting results, namely that undetected propagules, spores and endolithic filaments collected along with the 'bare' substrata and in situ seawater have been triggered to germinate, grow, and reproduce under laboratory conditions are far-reaching. We hypothesize the function of rhodoliths and rubble as marine seedbanks for biological diversity and explore the role of this ecosystem for community resilience following a major anthropogenic disaster. This is a speculative paper since we currently lack many rigorous, quantitative data. The paper is envisioned as a 'first step' in approaching the dynamics of rhodoliths and associated diversity following a catastrophic anthropogenic event, from which the algal and invertebrate diversity has not recovered, as of October 2013, our last collecting expedition to Ewing Bank in the NW Gulf of Mexico. [ABSTRACT FROM AUTHOR]