Marine Invertebrate Communities Research Articles

Pleistocene to Holocene continuity and discontinuity in California Northern Channel Island marine invertebrate communities

There is growing interest in analyzing interdisciplinary datasets to better understand the evolution of ecosystems through deep time. One burgeoning area has been the integration of archaeological and fossil data to evaluate the long-term structure and function of habitats, floral and faunal communities, and ecosystems. Here, marine invertebrate data from Holocene archaeological sites and Pleistocene marine terrace deposits on California's Northern Channel Islands are combined to glean insights into the long-term structure of nearshore marine ecosystems, the composition of intertidal marine invertebrate communities, and the formation of archaeological shell middens. While a variety of methodological, analytical, and taphonomic challenges in comparing disparate datasets from fossil and archaeological contexts were identified, we offer perspectives for surmounting these challenges in future research. These findings indicate that the integration of fossil and archaeological data, spanning tens of thousands of years, offers important insights on the evolution of nearshore coastal ecosystems and marine climate change in California and around the world.

Differences in fouling community composition and space occupation across broad spatial and temporal scales

Sessile marine invertebrate (biofouling) communities have served as an important model in ecology for evaluating fundamental patterns and processes, including invasion dynamics, which vary at broad spatial and temporal scales. Here, we tested for differences in biofouling community development among three biogeographically distinct bays in North America (Chesapeake Bay, Tampa Bay, and San Francisco Bay), exploring possible explanations for differential non-native species success. In particular, we aimed to examine if San Francisco Bay (a global hotspot for non-native species richness) differed in composition and space occupation, especially since open space can facilitate colonization. Additionally, we explored how biogeography, assembly and succession dynamics over the short and long term, and space availability affect marine communities across broad spatial scales. Patterns of community assembly differed among bays, with more bare space and less secondary cover (species settling on species) in San Francisco Bay. San Francisco Bay was also distinguished by a higher percent cover of Tunicata (almost all of which are non-native and historically absent) over multiple time scales. Cirripedia recruited on bare panels in all three Bays but cover increased only in Tampa Bay, as soak time increased. Tube-dwelling Polychaeta distinguished Chesapeake Bay from Tampa Bay and San Francisco Bay. Low-salinity events temporarily restructured the communities in all three bays. Whether differences among bays reflect coastal versus bay-specific patterns remains to be tested.

UV-filters in marine environments: a review of research trends, meta-analysis, and ecotoxicological impacts of 4-methylbenzylidene-camphor and benzophenone-3 on marine invertebrate communities.

The potential adverse effects of UV-filter pollution in marine environments have been the focus of research in recent years. This systematic review aims to determine the extent of this emerging problem, both quantitatively and qualitatively, combining temporal and science mapping analyses to explore the development of the field of UV-filters in the marine environment (from 1990 to 2021), and to outline new research frontiers. The temporal trend analysis revealed an exponential growth of published studies over the last decade (70% since 2016), confirming the emerging role of this topic in environmental science. The meta-analysis determined that 4-methylbenzylidene-camphor (4-MBC)and benzophenone-3(BP-3) are top-priority environmental pollutants due to their increasing usage and, in turn, a frequent occurrence in marine ecosystems. This meta-analysis determined the focus on these two contaminants for this review. A critical discussion of the applications, regulatory aspects, and environmental occurrences of these selectedcompounds was provided. The present study also focused on the most recent (2015-2021) field and laboratory studies investigating the ecotoxicological impactsof 4-MBC and BP-3 on marine invertebrates. This review highlights the need for moreresearch efforts to fill the knowledge gaps on the realistic effects these compounds may have when considered individually, in combination, or as subsequent exposures. Overall, this review aims to establish guidelines for further studies to understand the effect of UV-filters on marine ecosystems and marine invertebrate communities.

Predator control of marine communities increases with temperature across 115 degrees of latitude.

Early naturalists suggested that predation intensity increases toward the tropics, affecting fundamental ecological and evolutionary processes by latitude, but empirical support is still limited. Several studies have measured consumption rates across latitude at large scales, with variable results. Moreover, how predation affects prey community composition at such geographic scales remains unknown. Using standardized experiments that spanned 115° of latitude, at 36 nearshore sites along both coasts of the Americas, we found that marine predators have both higher consumption rates and consistently stronger impacts on biomass and species composition of marine invertebrate communities in warmer tropical waters, likely owing to fish predators. Our results provide robust support for a temperature-dependent gradient in interaction strength and have potential implications for how marine ecosystems will respond to ocean warming.

Estimating the integrated degradation rates of woody debris at the scale of a Mediterranean coastal catchment

Woody debris is found in all habitats of the land-sea continuum. While isolated experimental studies of wood degradation exist, few programs have observed the dynamics of wood degradation, in situ across this gradient. Since 2014, we have been conducting a series of long-term observations of wood decay in three characteristic areas of a Mediterranean Sea coastal watershed: forest leaf litter (‘Forest’), river bed (‘River’) and the near-shore marine environment (‘Sea’). The study sites are within the Massane River watershed (France) whose headwaters are in a protected beech tree (Fagus sylvatica) dominated forest. Branch sections from a recently fallen beech tree and standardized blocks of Norway spruce (Picea abies) were installed in all three environments. The proportion of remaining mass and volumetric mass of the individual wood samples were determined periodically over 4.2 years. Regardless of wood type, there were marked differences in the decay dynamics. Mass losses at the Forest and River sites were well-described by continuous negative exponential models. At the Sea site, there was a short latency period followed by rapid degradation for the wood fraction exploited by shipworms; in this case, a Weibull-type function was fitted to the data. Integrated mass loss rates at the coastal location were 6 to 20 times faster than in the other two environments. Our study suggests that the early dynamics of wood degradation in a land-sea meta-ecosystem are dominated by the marine invertebrate community. This means woody debris, once it reaches the sea, is likely to break down rapidly within near shore coastal habitats. These results highlight the need to quantify the mass transport dynamics between local ecosystems.

Stronger predation intensity and impact on prey communities in the tropics

The hypothesis that biotic interactions strengthen toward lower latitudes provides a framework for linking community-scale processes with the macroecological scales that define our biosphere. Despite the importance of this hypothesis for understanding community assembly and ecosystem functioning, the extent to which interaction strength varies across latitude and the effects of this variation on natural communities remain unresolved. Predation in particular is central to ecological and evolutionary dynamics across the globe, yet very few studies explore both community-scale causes and outcomes of predation across latitude. Here we expand beyond prior studies to examine two important components of predation strength: intensity of predation (including multiple dimensions of the predator guild) and impact on prey community biomass and structure, providing one of the most comprehensive examinations of predator-prey interactions across latitude. Using standardized experiments, we tested the hypothesis that predation intensity and impact on prey communities were stronger at lower latitudes. We further assessed prey recruitment to evaluate the potential for this process to mediate predation effects. We used sessile marine invertebrate communities and their fish predators in nearshore environments as a model system, with experiments conducted at 12 sites in four regions spanning the tropics to the subarctic. Our results show clear support for an increase in both predation intensity and impact at lower relative to higher latitudes. The predator guild was more diverse at low latitudes, with higher predation rates, longer interaction durations, and larger predator body sizes, suggesting stronger predation intensity in the tropics. Predation also reduced prey biomass and altered prey composition at low latitudes, with no effects at high latitudes. Although recruitment rates were up to three orders of magnitude higher in the tropics than the subarctic, prey replacement through this process was insufficient to dampen completely the strong impacts of predators in the tropics. Our study provides a novel perspective on the biotic interaction hypothesis, suggesting that multiple components of the predator community likely contribute to predation intensity at low latitudes, with important consequences for the structure of prey communities.

Janzen–Connell effects partially supported in reef‐building corals: adult presence interacts with settler density to limit establishment

In many plant and sessile marine invertebrate (SMI) taxa, population and community dynamics are heavily influenced by processes occurring during the dispersal and establishment phases. The Janzen–Connell (J–C) hypothesis predicts increased survival of early life stages with decreasing conspecific density and increased distance from conspecific adults. Evidence of J–C effects in maintaining diversity is common in plant communities, but its importance in SMI communities remains unclear. Under controlled aquarium conditions, we examined the effect of density‐dependence and adult conspecific water treatments (absent/present) on propagule settlement success and settler post‐settlement survival, along with associated spatial patterns, for six broadcast‐spawning, reef‐building coral species from three families. We also tested if settlement success was linked to increasing propagule species diversity for three coral species from two families. We found that the probability of settlement was density independent and not influenced by adult present water treatments. Yet, adult present water treatments and settler density did have a synergistic negative effect on the probability of short‐term settler survival for all species examined. Settlers also showed greater spatial aggregation as their numbers increased, but were less aggregated in adult present water treatments compared to those in adult absent water treatments. We further show evidence of significant species interactions among propagules, as settlement in single‐species trials was four‐fold higher compared to mixed‐species trials. Our findings from controlled experimental arenas indicate that the early establishment of corals was predominantly limited by density‐dependent settler–adult interactions among conspecifics and propagule–propagule interactions among heterospecifics. Thus, the proximity to established conspecific adults, settler density and species diversity of propagules are relevant drivers of local coral community diversity and structure. Based on these outcomes, we suggest that the J–C hypothesis, with demonstrated importance for plants, is partially upheld for reef corals.

Differential resource use in filter-feeding marine invertebrates.

Coexistence theory predicts that, in general, increases in the number of limiting resources shared among competitors should facilitate coexistence. Heterotrophic sessile marine invertebrate communities are extremely diverse but traditionally, space was viewed as the sole limiting resource. Recently planktonic food was recognized as an additional limiting resource, but the degree to which planktonic food acts as a single resource or is utilized differentially remains unclear. In other words, whether planktonic food represents a single resource niche or multiple resource niches has not been established. We estimated the rate at which 11 species of marine invertebrates consumed three phytoplankton species, each different in shape and size. Rates of consumption varied by a 240-fold difference among the species considered and, while there was overlap in the consumer diets, we found evidence for differential resource usage (i.e. consumption rates of phytoplankton differed among consumers). No consumer ingested all phytoplankton species at equivalent rates, instead most species tended to consume one of the species much more than others. Our results suggest that utilization of the phytoplankton niche by filter feeders is more subdivided than previously thought, and resource specialization may facilitate coexistence in this system. Our results provide a putative mechanism for why diversity affects community function and invasion in a classic system for studying competition.

Resilience of marine invertebrate communities during the early Cenozoic hyperthermals

The hyperthermal events of the Cenozoic, including the Paleocene-Eocene Thermal Maximum, provide an opportunity to investigate the potential effects of climate warming on marine ecosystems. Here, we examine the shallow benthic marine communities preserved in the late Cretaceous to Eocene strata on the Gulf Coastal Plain (United States). In stark contrast to the ecological shifts following the end-Cretaceous mass extinction, our data show that the early Cenozoic hyperthermals did not have a long-term impact on the generic diversity nor composition of the Gulf Coastal Plain molluscan communities. We propose that these communities were resilient to climate change because molluscs are better adapted to high temperatures than other taxa, as demonstrated by their physiology and evolutionary history. In terms of resilience, these communities differ from other shallow-water carbonate ecosystems, such as reef communities, which record significant changes during the early Cenozoic hyperthermals. These data highlight the strikingly different responses of community types, i.e., the almost imperceptible response of molluscs versus the marked turnover of foraminifera and reef faunas. The impact on molluscan communities may have been low because detrimental conditions did not devastate the entire Gulf Coastal Plain, allowing molluscs to rapidly recolonise vacated areas once harsh environmental conditions ameliorated.

IMPACT RESILIENCE: ECOLOGICAL RECOVERY OF A CARBONATE FACTORY IN THE WAKE OF THE LATE DEVONIAN IMPACT EVENT

ABSTRACT Conformable limestone deposits bracketing the Alamo breccia (Late Devonian, Nevada) provide a robust dataset for comparisons of depositional environments and marine communities before and after a significant meteor impact. Rank abundances of more than 3000 faunal identifications from 158 sampling localities cluster in three major faunal groups that are arranged in an onshore-offshore lithofacies gradient. Comparison of faunal clusters before and after the impact show little to no dissimilarity. The recovery of marine invertebrate communities following the Alamo impact event was geologically instantaneous. Broad geographic ranges of the fauna may have contributed to ecological resilience. From a geologic perspective, marine communities appear to rebound quickly and fully following meteor impacts, leaving impact-related extinctions as outliers that correspond only to the largest impacts.

Diatoms Dominate and Alter Marine Food-Webs When CO2 Rises

Diatoms are so important in ocean food-webs that any human induced changes in their abundance could have major effects on the ecology of our seas. The large chain-forming diatom Biddulphia biddulphiana greatly increases in abundance as pCO2 increases along natural seawater CO2 gradients in the north Pacific Ocean. In areas with reference levels of pCO2, it was hard to find, but as seawater carbon dioxide levels rose, it replaced seaweeds and became the main habitat-forming species on the seabed. This diatom algal turf supported a marine invertebrate community that was much less diverse and completely differed from the benthic communities found at present-day levels of pCO2. Seawater CO2 enrichment stimulated the growth and photosynthetic efficiency of benthic diatoms, but reduced the abundance of calcified grazers such as gastropods and sea urchins. These observations suggest that ocean acidification will shift photic zone community composition so that coastal food-web structure and ecosystem function are homogenised, simplified, and more strongly affected by seasonal algal blooms.

Comparing eDNA metabarcoding and species collection for documenting Arctic metazoan biodiversity

AbstractBackgroundArctic biodiversity has long been poorly documented and is now facing rapid transformations due to ongoing climate change and other impacts, including shipping activities. These changes are placing marine coastal invertebrate communities at greater risk, especially in sensitive areas such as commercial ports. Preserving biodiversity is a significant challenge, going far beyond the protection of charismatic species and involving suitable knowledge of the spatiotemporal organization of species. Therefore, knowledge of alpha, beta, and gamma biodiversity is of great importance to achieve this objective, particularly when partnered with new cost‐effective approaches to monitor biodiversity.Method and resultsThis study compares metabarcoding of COI mitochondrial and 18S rRNA genes from environmental DNA (eDNA) water samples with standard invertebrate species collection methods to document community patterns at multiple spatial scales. Water samples (250 ml) were collected at three different depths within three Canadian Arctic ports: Churchill, MB; Iqaluit, NU; and Deception Bay, QC. From these samples, 202 genera distributed across more than 15 phyla were detected using eDNA metabarcoding, of which only 9%–15% were also identified through species collection at the same sites. Significant differences in taxonomic richness and community composition were observed between eDNA and species collections at both local and regional scales. This study shows that eDNA dispersion in the Arctic Ocean reduces beta diversity in comparison with species collections while emphasizing the importance of pelagic life stages for eDNA detection.ConclusionThe study also highlights the potential of eDNA metabarcoding to assess large‐scale Arctic marine invertebrate diversity while emphasizing that eDNA and species collection should be considered as complementary tools to provide a more holistic picture of coastal marine invertebrate communities.

Marine collections and global digital repositories as source data to assess the effects of habitat condition and biodiversity loss on African Coastal ecosystem functioning and services

Natural history collections (NHC) worldwide contain vast amount of valuable data that can be used to answer a wide range of questions by exploring biodiversity and natural resources records, having an immense potential to contribute to science, policy making and legislating, and to public scientific awareness. Likewise, the development and increase of global and regional biodiversity digital databases (e.g., Global Biodiversity Information Facility - GBIF; Fauna Europaea; Naturdata, etc.), scientific literature and all digital information regarding biodiversity, ecological areas and climate records comprise a huge amount of primary and processed digital ecological data (DED) accessible globally that can be readily used, at no cost, and integrated to further study e.g. biodiversity changes, ecological processes, natural habitat distribution, prioritizing ecosystem management and conservation actions, etc. Marine invertebrate biodiversity contributes to the structure and stability of ecosystem processes such as productivity, ecological networks, as well as nutrient and biogeochemical cycling having also an economic importance as a food source for local populations. Mangroves and seagrasses encompass ecological and socio-economic relevance as they have a preponderant role in marine and coastal ecosystem biodiversity and functioning providing a vast number of goods and services to local populations. Although generally pristine, mangroves and seagrasses in Africa are extremely vulnerable to the increased migration of rural populations to urban coastal areas and to extreme climate events. As a result, human activities such as construction, agriculture and food harvesting, provoke habitat degradation and biodiversity loss which will have further devastating consequences. The degradation and unsustainable use of these ecosystems have major drawbacks to the elimination of extreme poverty because this is one of the key factors that drive environmental degradation and biodiversity loss. The main goal of this work is to use NHC and digital repositories data (including scientific literature) to assess how biodiversity loss and habitat degradation affect ecosystem functioning and services provided by marine invertebrate communities of mangroves and seagrass meadows in the West and East African coast, using the case study of Mozambique and Príncipe’s Island. These will lead to the construction of a comprehensive dataset, an ecological model and a framework adapted to marine invertebrate biodiversity from Mozambique’s (MZ) and São Tomé and Príncipe’s (STP) mangroves and seagrasses as tools:1) integrate and disseminate marine invertebrate biodiversity data gathered along a spatio-temporal scale; 2) compare marine invertebrate assemblies from pristine and impacted habitats in African countries and predict the progress of these communities to habitat degradation and biodiversity loss; and 3) manage ecosystem functioning and services delivered by marine invertebrate assemblages under anthropogenic and environmental pressure scenarios. Specifically this project intends to: compile and integrate the available information contained in NHC and DED to develop a comprehensive spatio-temporal dataset on marine invertebrate biodiversity (e.g. species, number of individuals, local of occurrence and georeferencing, date of collection/observation), as well as mangroves and seagrasses distribution along the Mozambique’s and Príncipe’s coasts; assess different indexes of invertebrate marine biodiversity, biodiversity and habitat spatio-temporal distribution; develop an ecological network approach to assess the functional links of marine invertebrate communities within the studied habitats, and to refine their role in ecosystem functioning, as well as ecosystem services (ES) provided by marine invertebrates in mangroves and seagrasses from MZ and STP; construct a model to evaluate the ecological responses of mangrove and seagrass invertebrate communities to habitat degradation and biodiversity loss and to predict multi-dimensional (spatial, temporal, and social) trade-offs in local/regional ecosystem services along a spatio-temporal gradient; develop a practical framework to manage and preserve ecosystem functioning and services delivered by mangrove and seagrass marine invertebrates under a global change scenario. compile and integrate the available information contained in NHC and DED to develop a comprehensive spatio-temporal dataset on marine invertebrate biodiversity (e.g. species, number of individuals, local of occurrence and georeferencing, date of collection/observation), as well as mangroves and seagrasses distribution along the Mozambique’s and Príncipe’s coasts; assess different indexes of invertebrate marine biodiversity, biodiversity and habitat spatio-temporal distribution; develop an ecological network approach to assess the functional links of marine invertebrate communities within the studied habitats, and to refine their role in ecosystem functioning, as well as ecosystem services (ES) provided by marine invertebrates in mangroves and seagrasses from MZ and STP; construct a model to evaluate the ecological responses of mangrove and seagrass invertebrate communities to habitat degradation and biodiversity loss and to predict multi-dimensional (spatial, temporal, and social) trade-offs in local/regional ecosystem services along a spatio-temporal gradient; develop a practical framework to manage and preserve ecosystem functioning and services delivered by mangrove and seagrass marine invertebrates under a global change scenario.

Metabolic scaling across succession: Do individual rates predict community‐level energy use?

Abstract A major goal of metabolic ecology is to make predictions across scales such that individual metabolic rates might be used to predict the metabolic rates of populations and communities, but the success of these predictions is unclear given the rarity of tests. Given that older communities tend to have species with slower life histories and larger body sizes, we hypothesized that the metabolism of whole communities should scale allometrically with their mass across successional stages. We created experimental chronosequences of sessile marine invertebrate communities in the field. We then (1) determined the metabolic scaling of these whole communities across successional stages of different mass and (2) tested whether the sum of individual metabolic rates for the dominant species could predict overall community metabolism. Contrary to what we expected based on metabolic theory and succession theory, community metabolism scaled isometrically with mass across succession, despite the mean body size of dominant individuals within the communities increasing over time. We resolved this paradox by estimating community metabolism based on individual metabolic rates for the dominant species in the community. We show that non‐random changes in the membership of the species maintain mass‐specific metabolic rates of the whole community invariant across succession despite changes in size structure. These results suggest that simple assumptions about how community‐level processes scale up from species are unlikely to be correct, because community turnover is non‐random with respect to metabolic rate. Nevertheless, with the appropriate parametrization, the sum of individual species rates can predict the function of the community as a whole. A plain language summary is available for this article.

Long‐term, spatial marine harvest intensity as an indicator of human impact on shallow rocky reef ecosystems

AbstractAs human activities continue to expand globally, there will be increased need to incorporate the impacts of these activities into ecological studies for a holistic understanding of ecosystems. Within the Southern California Bight, as in other highly productive marine ecosystems, fishing has long contributed to the ecology and evolution of marine fish and invertebrate communities. As fishing varies across space and over time, there is a need for a reliable metric that quantifies the spatiotemporal variation in the impact of fishing. Here, we quantify an index of harvest intensity on the highly productive and heavily fished, shallow rocky reefs of Southern California. To this end, we take advantage of two long‐term, spatially explicit, multi‐species datasets collected by the California Department of Fish and Wildlife on commercial and recreational marine harvest, combined with reef‐species survey data and a geospatial reef data layer. Using this approach, we recover predictable patterns for harvest intensity across the Southern California Bight, with harvest intensity decreasing in fishing blocks located at greater distances from the nearest port. Further, our results indicate an important interaction effect between distance to nearest port and year on harvest intensity, suggesting there are important shifts in spatiotemporal patterns over the 30‐year time period. As fishing can have numerous impacts on ecological and evolutionary processes, the observed spatiotemporal variation in harvest intensity illustrates the need for incorporating the contribution of human impacts into marine ecosystem studies.

Regional surveys of macrobenthic shelf invertebrate communities in Onslow Bay, North Carolina, U.S.A.

Despite its importance for quantifying ecosystem responses to environmental and anthropogenic drivers, our understanding of spatial heterogeneity in marine communities remains inadequate. Studies in coastal marine benthic habitats are sparse, and predominantly target single higher taxonomic groups. Here we describe macrobenthic marine invertebrate community surveys from 52 localities in Onslow Bay (Beaufort, North Carolina, U.S.A.), over an extensive geographic area (~200 km2). The data consist of 11,467 individuals, 175 species, and 7 phyla. The data include species abundance data for each sample at all localities, and corresponding species lists and locality information. The metadata describe the sampling protocols and localities. The data provided here will facilitate examination of assemblage heterogeneity with regards to spatial and temporal patterns, and depth gradient analyses.

Consequences of biodiversity loss diverge from expectation due to post-extinction compensatory responses

Consensus has been reached that global biodiversity loss impairs ecosystem functioning and the sustainability of services beneficial to humanity. However, the ecosystem consequences of extinction in natural communities are moderated by compensatory species dynamics, yet these processes are rarely accounted for in impact assessments and seldom considered in conservation programmes. Here, we use marine invertebrate communities to parameterise numerical models of sediment bioturbation – a key mediator of biogeochemical cycling – to determine whether post-extinction compensatory mechanisms alter biodiversity-ecosystem function relations following non-random extinctions. We find that compensatory dynamics lead to trajectories of sediment mixing that diverge from those without compensation, and that the form, magnitude and variance of each probabilistic distribution is highly influenced by the type of compensation and the functional composition of surviving species. Our findings indicate that the generalized biodiversity-function relation curve, as derived from multiple empirical investigations of random species loss, is unlikely to yield representative predictions for ecosystem properties in natural systems because the influence of post-extinction community dynamics are under-represented. Recognition of this problem is fundamental to management and conservation efforts, and will be necessary to ensure future plans and adaptation strategies minimize the adverse impacts of the biodiversity crisis.

Metagenomic analysis of the marine coastal invertebrates of South Korea as assessed by Ilumina MiSeq

ABSTRACTMetagenomic analysis was carried out for the first time on the marine coastal invertebrates of South Korea. Samples collected from coastal areas of Korea were filtered through a 63 µm mesh, then their 18S rDNA V4 regions were amplified. High-throughput sequencing of PCR amplicons using Illumina MiSeq and BLAST against the SILVA database showed that a total of 319 eukaryotic Operational Taxonomic Units were identified at the species level. Annelida, Arthropoda, Mollusca, Nematoda, and Platyhelminthes and for 92.23% of the total 103 metazoan species belonging to 101 genera, 75 families, and 10 phyla. Of these, several taxa previously unreported to exist in Korea were detected at the family level compared with the integrated database from three main Korean biodiversity DBs (MABIK, KOMBIS, and MRBR). Analysis of beta diversity of the community structure of invertebrates indicated that the composition of marine invertebrates is likely to be affected by habitat type rather than geographical distance. The present study showed that metagenomic high-throughput technology can be used to unravel species diversity and for various studies regarding marine invertebrate community structure.

Night-time lighting alters the composition of marine epifaunal communities.

Marine benthic communities face multiple anthropogenic pressures that compromise the future of some of the most biodiverse and functionally important ecosystems in the world. Yet one of the pressures these ecosystems face, night-time lighting, remains unstudied. Light is an important cue in guiding the settlement of invertebrate larvae, and altering natural regimes of nocturnal illumination could modify patterns of recruitment among sessile epifauna. We present the first evidence of night-time lighting changing the composition of temperate epifaunal marine invertebrate communities. Illuminating settlement surfaces with white light-emitting diode lighting at night, to levels experienced by these communities locally, both inhibited and encouraged the colonization of 39% of the taxa analysed, including three sessile and two mobile species. Our results indicate that ecological light pollution from coastal development, shipping and offshore infrastructure could be changing the composition of marine epifaunal communities.

Limiting resources in sessile systems: food enhances diversity and growth of suspension feeders despite available space.

Much of our understanding of competition comes trom onservations in sessue systems, such as rainforests and marine invertebrate communities. In terrestrial systems, sessile species often compete for multiple limiting resources (i.e., space, light, and nutrients), but in marine systems, space is viewed as the primary or sole limiting resource. Competition theory, on the other hand, suggests that competition for a single limiting resource is unlikely to maintain high species diversity, but manipulative tests of competition for other resources in marine benthic systems are exceedingly rare. Here, we manipulate the availability of food for a classic system, marine sessile invertebrate communities, and investigate the effects on species diversity, abundance, and composition during early succession as well as on the growth of bryozoan populations in the field. We found the number of species to be greater, available space to be lower, and the community composition to be different in assemblages subjected to increased food availability compared to controls. Similarly, laboratory-settled bryozoans deployed into the field grew more in the presence of enhanced food. Our results suggest that food can act as a limiting resource, affecting both diversity and abundance, even when bare space is still available in hard-substratum communities. Consequently, broadening the view of resource limitation beyond solely space may increase our understanding and predictability of marine sessile systems.