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Community similarity among macroinvertebrate species assemblages from 12 exposed rocky headlands surveyed in 2004, 2007, and 2012 was examined to resolve mesoscale patterns along an east–west linear distance of 366 km in the coastal Gulf of Maine. The goals were: (1) detect latitudinal patterns of species assemblage similarity and (2) relate species assemblage similarities to environmental factors. Assemblage similarities were correlated with latitude. There was a distinguishable grouping of sampling sites fitting two Gulf regions that separate at mid-coast Maine. This pattern was uniquely intertidal and not shown by subtidal species assemblages. β diversity was high, did not differ between regions, and species turnover accounted for 91% of it. Molluscs and crustaceans, major components of surveyed communities, contributed most of the dissimilarity between regions. Satellite-derived shore and sea surface temperatures explained a significant amount of the variation responsible for producing regional patterns. The regions corresponded with the two principal branches of the Gulf of Maine Coastal Current. These hydrographic features and associated environmental conditions are hypothesized to influence community dynamics and shape the dissimilarity between Gulf regions. The predicted warming of the Gulf of Maine portend change in species turnover from species invasions and range shifts potentially altering rocky intertidal community patterns.

Benthic ecosystems are chronically undersampled, particularly in environments >50 m depth. Yet a rising level of anthropogenic threats makes data collection ever more urgent. Currently, modern underwater sampling tools, particularly autonomous underwater vehicles (AUVs), are able to collect vast image data, but cannot bypass the bottleneck formed by manual image annotation. Computer vision (CV) offers a faster, more consistent, cost effective and sharable alternative to manual annotation. We used TensorFlow to evaluate the performance of the Inception V3 model with different numbers of training images, as well as assessing how many different classes (taxa) it could distinguish. Classifiers (models) were trained with increasing amounts of data (20 to 1000 images of each taxa) and increasing numbers of taxa (7 to 52). Maximum performance (0.78 sensitivity, 0.75 precision) was achieved using the maximum number of training images but little was gained in performance beyond 200 training images. Performance was also highest with the least classes in training. None of the classifiers had average performances high enough to be a suitable alternative to manual annotation. However, some classifiers performed well for individual taxa (0.95 sensitivity, 0.94 precision). Our results suggest this technology is currently best applied to specific taxa that can be reliably identified and where 200 training images offers a good compromise between performance and annotation effort. This demonstrates that CV could be routinely employed as a tool to study benthic ecology by non-specialists, which could lead to a major increase in data availability for conservation research and biodiversity management.

Cold seeps are locations where hydrocarbons emanate from the seabed, fueling chemoautotrophic production that may support macrofaunal communities via chemosymbiosis or trophic interactions. The recent discovery of offshore sub-seabed gas reservoirs and venting methane at the seabed in Svalbard (75 to 79° N) provides the context to examine the influence of cold seeps on macrofaunal community structure in the high-Arctic. We compared benthic macrofaunal community structure from cold-seep environments and paired control stations from 3 regionally distinct areas along the western Svalbard margin and the western Barents Sea. Specialized seep-related polychaetes (e.g. siboglinid tubeworms) were found at seep stations in the Barents Sea in high densities (up to 7272 ind. m−2). The presence of obligate seep-associated faunal taxa demonstrates that chemoautotrophic production, fueled by methane and sulfur, influences benthic communities at these seeps. Further, total biomass was significantly higher at seep-impacted stations compared to controls (mean = 20.7 vs. 9.8 g wet weight sample−1), regardless of region. Four methane seep-influenced samples showed clear indications of seep impact, with reduced diversity and with a few species dominating, compared to controls. Our results demonstrate that the effect of methane seeps on the Svalbard shelf benthic community are highly localized (i.e. meter scale), reflecting strong gradients associated with the point-source impacts of individual seeps. Regional differences and the restricted spatial extent of focused emissions likely drive the observed complexity and heterogeneity at Svalbard cold seeps. These results provide key baseline observations in a high-Arctic location that is likely to be influenced by warming sea temperatures, which may lead to increased seabed methane release.

The spatial structure of ecological communities on tropical coral reefs across seascapes and geographies have historically been poorly understood. Here we addressed this for the first time using spatially expansive and thematically resolved benthic community data collected around five uninhabited central Pacific oceanic islands, spanning 6° latitude and 17° longitude. Using towed‐diver digital image surveys over ~140 linear km of shallow (8–20 m depth) tropical reef, we highlight the autocorrelated nature of coral reef seascapes. Benthic functional groups and hard coral morphologies displayed significant spatial clustering (positive autocorrelation) up to kilometre‐scales around all islands, in some instances dominating entire sections of coastline. The scale and strength of these autocorrelation patterns showed differences across geographies, but patterns were more similar between islands in closer proximity and of a similar size. For example, crustose coralline algae (CCA) were clustered up to scales of 0.3 km at neighbouring Howland and Baker Islands and macroalgae were spatially clustered at scales up to ~3 km at both neighbouring Kingman Reef and Palmyra Atoll. Of all the functional groups, macroalgae had the highest levels of spatial clustering across geographies at the finest resolution of our data (100 m). There were several cases where the upper scale at which benthic community members showed evidence of spatial clustering correlated highly with the upper scales at which concurrent gradients in physical environmental drivers were spatially clustered. These correlations were stronger for surface wave energy than subsurface temperature (regardless of benthic group) and turf algae and CCA had the closest alignments in scale with wave energy across functional groups and geographies. Our findings suggest such physical drivers not only limit or promote the abundance of various benthic competitors on coral reefs, but also play a key role in governing their spatial scaling properties across seascapes.

Baited Remote Underwater Video Systems (BRUVS) are a valuable, non‐destructive marine monitoring technology, suitable for a wide variety of monitoring goals. BRUVS remain underutilized in low‐light and remote environments, where the requirement for additional lighting, extended deployments, and repeated site access can increase costs and complexity, limiting data collection. This study presents BRUVS‐Lite, a new open‐source stereo‐BRUVS with integrated lights. The design incorporates purpose‐designed and consumer‐available components to generate a user‐friendly, cost‐effective technology capable of providing high‐quality imagery in low‐light environments, over extended deployment periods and to 500 m depth. The effectiveness of BRUVS‐Lite was evaluated at multiple locations and marine habitats surrounding Nova Scotia, Canada, demonstrating its suitability for benthic monitoring in low‐light environments.

Echinoderms play a key role in structuring many marine ecosystems and are notorious for large population density variations in so-called \"outbreak\" or \"dieoff\" events. In a review of this phenomenon, we assess the causal factors and ecological and evolutionary consequences. We identified 28 species (6 Asteroidea, 8 Echinoidea, 10 Holothuroidea, 4 Ophiuroidea) that exhibit large (more than two population doublings or halvings) population density changes. Three generalized patterns were identified and named for exemplary species: (1) rapid decreases followed by no or slow recovery (Diadema—Paracentrotus Model), (2), rapid increase and apparent stability at a new population density (Amperima—Amphiura Model), and (3) population density fluctuations (Acanthaster—Asterias Model). Echinoderms identified were distributed from the shallow intertidal to the deep sea, and from tropical to temperate regions. In most cases, significant impacts on the respective ecosystems were observed. The most striking similarity among all species identified was possession of the ancestral-type planktotrophic larva. This larval type was significantly overrepresented in species identified within the Asteroidea, Echinoidea, Holothuroidea, and for the combined data set. We suggest three main factors that render a life history with planktotrophic larvae a high-risk-high-gain strategy: (1) a strong nonlinear dependency of larval production on adult densities (Allee effects), (2) a low potential for compensatory feedback mechanisms, and (3) an uncoupling of larval and adult ecology. The alternative (derived) lecithotrophic larva occurs in 68% of recent echinoderm species, suggesting an evolutionary trend toward this larval type. Lecithotrophic development represents a more buffered life history because compensatory feedback between adult densities and larval output is likely to be more efficient. For lecithotrophic developers, direct nutritive coupling from adult to larva to the early benthic juvenile provides a buffer against starvation. Lecithotrophic larvae are independent of the vagaries of planktonic food supply, and their short planktonic duration may promote local recruitment. Anthropogenic influences contributed to the population density variations in most cases, including increased primary productivity through eutrophication or global change, disease, overfishing, and species introductions. We suggest that anthropogenic disturbance, through its influence on the frequency and/or amplitude of echinoderm population density changes, may go beyond present ecosystem impacts and alter future evolutionary trends.

Measuring infaunal population dynamics relies on destructive sampling that disturbs sediments and removes animals from their habitat. Establishing effective, non-invasive sampling methods for monitoring infaunal populations can reduce the impact of scientific sampling and facilitate efficient population assessments. Using intertidal soft-shell clams (Mya arenaria L.) in eastern Canada, we explored whether population density and size structure could be estimated from visible siphon holes. Across four sites with varying sediment characteristics and infaunal species assemblages, we predicted the presence of M. arenaria with 78–100% accuracy by visually assessing siphon holes. Smaller holes (< 7.5 mm) were more likely to be misidentified. Siphon hole count was a strong predictor of actual clam count and biomass at most sites, except the site with wet muddy sediment and high densities of other infaunal species. Siphon hole length was positively related to clam shell length and wet weight at all sites; however, relationships typically had low R2 values (< 0.35). Ultimately, visual assessments of intertidal siphon holes can be effective for estimating M. arenaria densities and size structure in some habitats. Testing the application of this method to other habitats and species is warranted.

Okhotsk or western gray whales feed in summer along the northeastern coast of Sakhalin Island, Russia, a region with oil and gas extraction facilities. Seismic surveys increased sound levels in the nearshore feeding area in 2015 for part of the summer, potentially displacing whales from preferred foraging habitat or reducing foraging efficiency. Since lost foraging opportunities might lead to vital rate effects on this endangered species, detailed benthic surveys were conducted to characterize benthic community biomass patterns and spatial and temporal differences. Benthic biomass demonstrated strong spatial–temporal interactions indicating that prey biomass differences among locations were dependent on sampling period. Of greatest interest, Amphipoda biomass declined from June to October in the northern and southern portions of the nearshore study area but increased in the middle and Actinopterygii biomass increased in the northern area in mid-summer. Water depth and sediment type were significant covariates with community structure, and water depth strongly covaried with bivalve biomass. Total average prey biomass was ~ 100 g/m 2 within the nearshore feeding area with no evidence of reduced biomass among sampling periods or locations, although there were fewer amphipods in the south. Multi-prey investigations provide a stronger basis for inferences than single-prey studies of amphipods when gray whales feed on diverse prey. Benthic community-level variability was moderate to high as would be expected for a shallow-water nearshore area. Overall, spatial and temporal changes in dominant macrofauna biomass reflected small to medium-sized effects that were well within the natural boundaries expected for benthic communities.

Many terrestrial plant and marine benthic communities involve intense competition for space as a means to survive and reproduce. Superior competitors can dominate other species numerically with high reproductive rates, indirectly with high growth rates that facilitate space acquisition, or directly with competitive overgrowth. To assess how climate change could affect competitive interactions, we examined latitudinal patterns in growth rates and overgrowth competition via field surveys and experiments with marine epibenthic communities. Epibenthic fouling communities are dominated by invasive tunicates, bryozoans, and other species that grow on docks, boats, and other artificial structures. Fouling communities are space limited, so growth rate and overgrowth competition play an important role in shaping abundance patterns. We experimentally assessed temperature-dependent growth rates of several tunicates and bryozoans in eight regions spanning the U.S. east and west coasts. Several species displayed positive growth responses to warmer temperature in the northern portions of their latitudinal ranges, and vice versa. We used photo surveys of floating docks in at least 16 harbors in each region to compare communities and overgrowth competition. There was a strong correlation across species and regions between growth rate and competitive ability, indicating that growth plays an important role in competitive outcomes. Because growth rates are typically temperature dependent for organisms that compete for space, including terrestrial plants, fungi, algae, bacteria, and sessile benthic organisms, global warming could affect competitive outcomes. Our results suggest that these competitive shifts can be predicted by species' relative growth rates and latitudinal ranges.

iKaluk, Inuttitut for Arctic charr ( Salvelinus alpinus ), holds significant commercial and cultural value for Inuit communities throughout Nunatsiavut. Studies evaluating iKaluk habitat associations in freshwater are plentiful; however, there is limited information on the ecological makeup and sediment characteristics of anadromous charr habitats in marine environments. This study investigated the benthic associations of Arctic charr during their marine residency period in Nain, Nunatsiavut, using underwater videos, harvester-identified fishing locations, and acoustic telemetry. Drop-camera surveys were deployed on previously placed hydrophone acoustic receivers and within harvester-identified fishing locations to describe and quantify available benthic habitats in the study area. Telemetry information was used to identify charr occupancy hotspots, and calculate habitat suitability indices. A total of 248,056 benthic organisms belonging to 63 morphotaxa were identified within the 125 video drops used for benthic community characterization and these represented five faunal assemblages. Marine phase charr occupied estuaries to a greater degree than other fjord or coastal headland environments and these habitats were typically characterized by fine sediments covered by high densities of brittle stars (Ophiuroidea spp.) and benthic diatom mats. The consistent presence of diatomaceous sediments is indicative of abundant foraging opportunities. The importance of these habitats to iKaluk, need to be considered in future marine planning given the cultural and ecological value of this species to many northern communities that face growing threats from environmental change.