Hard substrate in the deep ocean: How sediment features influence epibenthic megafauna on the eastern Canadian margin

Lacharité, Myriam; Meta×as, Anna

doi:10.1016/j.dsr.2017.05.013

Cited by 27 publications

(20 citation statements)

References 42 publications

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“…The differences in abundances and assemblage structure between sides of the seamount is likely instead influenced by POC and the westward current ( Table 2). Increases in rugosity, substrate variability, and slope variability increase habitat complexity, which has been shown to support higher levels of diversity, which in turn affects assemblage structure (Lacharité and Metaxas, 2017).…”

Section: Assemblage Structurementioning

confidence: 99%

Fine Scale Assemblage Structure of Benthic Invertebrate Megafauna on the North Pacific Seamount Mokumanamana

et al. 2019

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Changes in benthic megafaunal assemblage structure have been found across gradients of environmental variables for many deep-sea habitats, but patterns remain under-investigated on seamounts. To assess the extent of variability in benthic communities at the scale of within a single seamount, and to assess environmental drivers of assemblage changes, Mokumanamana, also known as Necker Island, a seamount in the Papahānaumokuākea Marine National Monument with no known history of human impacts, was surveyed. Replicate 1 km transects were conducted along depth contours at 50 m depth intervals from 200-700 m on three sides of Mokumanamana using the AUV Sentry. Megafaunal abundance and substrate parameters were obtained from 26,119 total images. The dominant megafaunal taxa were sponges, corallimorpharians, cup corals, and benthic ctenophores. Sea pens and alcyonacean octocorals were also abundant. Overall, abundance and diversity of megafauna increased with depth. Beta-diversity through species substitution with depth was very high. Beta-diversity was also high between the sides and likewise defined almost exclusively by species substitution. Crossed ANOSIM by depth and side showed community structure differed on Mokumanamana for both factors. NMDS and cluster analyses of Mokumanamana show nine assemblages that were defined by depth and reflect differences between sides of the seamount. Environmental modeling with DISTLM indicates sediment, oxygen, substrate variability and roughness, POC, and surface currents are correlated with these assemblage differences. These results suggest that microhabitats on seamounts can promote unique assemblages along depth gradients as well as on different sides of a feature, and this diversity may be easily overlooked without fine-scale sampling. These findings have implications for management and conservation of seamounts as well as future ecological studies of seamounts, as seamounts are generally sampled on much coarser spatial scales.

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Section: Assemblage Structurementioning

confidence: 99%

Fine Scale Assemblage Structure of Benthic Invertebrate Megafauna on the North Pacific Seamount Mokumanamana

et al. 2019

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“…The addition of hard substrata, in the form of dropstones, to soft-sediment dominated benthic landscapes at fjord and shelf floors enhances habitat heterogeneity, potentially influencing biodiversity. Habitat heterogeneity has been shown to increase diversity in many ecosystems, ranging from forests to abyssal plains (MacArthur & Wilson 1967, Simberloff 1974, Huston 1979, McClintock et al 2005, Schön-berg & Fromont 2012, Amon et al 2016), but the contribution of glacial debris to habitat heterogeneity has been assessed at only a few locations on continental shelves (Oschmann 1990, Starmans et al 1999, Schulz et al 2010, Meyer et al 2015, Lacharité & Metaxas 2017. On the Antarctic shelf, the most influential factors affecting benthic biodiversity are postulated to be disturbance (e.g.…”

Section: Introductionmentioning

confidence: 99%

Glacial dropstones: islands enhancing seafloor species richness of benthic megafauna in West Antarctic Peninsula fjords

Ziegler¹,

Smith²,

Edwards³

et al. 2017

Mar. Ecol. Prog. Ser.

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The West Antarctic Peninsula (WAP) margin is dominated by glaciomarine fjords and has experienced rapid climate warming in recent de cades. Glacial calving along the peninsula delivers icerafted debris (e.g. dropstones) to heavily sedimented fjord basins and the open continental shelf. Dropstones provide hard substrate, increase habitat heterogeneity, and may function as island habitats surrounded by mud. We used seafloor photographic transects to evaluate the distribution and community structure of Antarctic hard-substrate megafauna and the role of dropstones as island habitats in 3 WAP fjords and at 3 nearby shelf stations. Several lines of evidence indicate that dropstones function as island habitats; their communities adhere to principles of island biogeography theory with (1) a positive correlation between dropstone size and species richness, (2) an increase in the proportion of colonized dropstones with increasing dropstone size, and (3) a species−area scaling exponent consistent with island habitats measured globally. Previous work on the soft-sediment megafauna of this region found strong differences in community composition between fjord and shelf sites, whereas we found that dropstone communities differed within sites at small scales (1 km and smaller). We identified 73 megafaunal morphotypes associated with dropstones, 29 of which were not previously documented in the soft-sediment megafauna. While dropstones constituted <1% of the total seafloor area surveyed, they contributed 20% of the overall species richness of WAP megabenthos at depths of 437−724 m. WAP dropstone communities adhere to key principles of island biogeography theory, contribute environmental heterogeneity, and increase biodiversity in the WAP region.A rich community of megafauna inhabiting a glacial dropstone in Flandres Bay (400 m), a glaciomarine fjord on the West Antarctic Peninsula.Photo: Dr. Craig R. Smith

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“…6E). Unlike the tetractinellid sponge grounds of the Flemish Cap, which primarily settle on soft sandy/ muddy substrate with few cobbles and boulders, V. pourtalesi settles on hard substrate, which has also shown to increase habitat complexity and enhance the diversity of local fauna (Lacharité & Metaxas 2017). The presence of V. pourtalesi and percent cover of hard substrate were both statistically significant predictors of species density and abundance.…”

Section: Discussionmentioning

confidence: 93%

“…We compare the composition of species, diversity, and abundance of epibenthos from in situ photographs collected in areas with and without the presence of V. pourtalesi. Using generalized linear models (GLMs), the importance of this sponge ground in enhancing fine-scale diversity and abundance of the associated megafauna was evaluated against that of the presence (percent cover) of hard substrate, which has also been shown to enhance the diversity of local fauna in deep-sea environments (Lacharité & Metaxas 2017). Furthermore, broader-scale associations between V. pourtalesi and bentho-pelagic fish and invertebrate species collected from the DFO bottom trawl surveys were examined.…”

Section: Introductionmentioning

confidence: 99%

Glass sponge grounds on the Scotian Shelf and their associated biodiversity

Hawkes¹,

Korabik²,

Beazley³

et al. 2019

Mar. Ecol. Prog. Ser.

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Emerald Basin on the Scotian Shelf off Nova Scotia, Canada, is home to a globally unique population of the glass sponge Vazella pourtalesi. Through the analysis of both in situ photo graphs and trawl catch data from annual multispecies bottom-trawl surveys, we examined community composition, species density, and abundance of epibenthos and fish associated with V. pourtalesi compared to locations without this sponge. Using generalized linear models and analysis of similarities, the importance of V. pourtalesi in enhancing species density and abundance of the associated epibenthic community was assessed against that of the hard substrate on which it settles. Our results indicated that the megafaunal assemblage associated with V. pourtalesi was significantly different in composition and higher in species density and abundance compared to locations without V. pourtalesi. Analysis of similarity of trawl catch data indicated that fish communities associated with the sponge grounds are significantly different from those without V. pourtalesi, although no species were found exclusively on the sponge grounds. Our study provides further evidence of the role played by sponge grounds in shaping community structure and biodiversity of associated deep-sea epibenthic and fish communities. The mechanism for biodiversity enhancement within the sponge grounds formed by V. pourtalesi is likely the combined effect of both the sponge itself and its attachment substrate, which together comprise the habitat of the sponge grounds. We also discuss the role of habitat provision between the mixed-species tetractinellid sponges of the Flemish Cap and the monospecific glass sponge grounds of Emerald Basin.

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Hard substrate in the deep ocean: How sediment features influence epibenthic megafauna on the eastern Canadian margin

Cited by 27 publications

References 42 publications

Fine Scale Assemblage Structure of Benthic Invertebrate Megafauna on the North Pacific Seamount Mokumanamana

Fine Scale Assemblage Structure of Benthic Invertebrate Megafauna on the North Pacific Seamount Mokumanamana

Glacial dropstones: islands enhancing seafloor species richness of benthic megafauna in West Antarctic Peninsula fjords

Glass sponge grounds on the Scotian Shelf and their associated biodiversity

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