Patterns and Variation in Benthic Biodiversity in a Large Marine Ecosystem

Abstract

While there is a persistent inverse relationship between latitude and species diversity across many taxa and ecosystems, deviations from this norm offer an opportunity to understand the conditions that contribute to large-scale diversity patterns. Marine systems, in particular, provide such an opportunity, as marine diversity does not always follow a strict latitudinal gradient, perhaps because several hypothesized drivers of the latitudinal diversity gradient are uncorrelated in marine systems. We used a large scale public monitoring dataset collected over an eight year period to examine benthic marine faunal biodiversity patterns for the continental shelf (55–183 m depth) and slope habitats (184–1280 m depth) off the US West Coast (47°20′N—32°40′N). We specifically asked whether marine biodiversity followed a strict latitudinal gradient, and if these latitudinal patterns varied across depth, in different benthic substrates, and over ecological time scales. Further, we subdivided our study area into three smaller regions to test whether coast-wide patterns of biodiversity held at regional scales, where local oceanographic processes tend to influence community structure and function. Overall, we found complex patterns of biodiversity on both the coast-wide and regional scales that differed by taxonomic group. Importantly, marine biodiversity was not always highest at low latitudes. We found that latitude, depth, substrate, and year were all important descriptors of fish and invertebrate diversity. Invertebrate richness and taxonomic diversity were highest at high latitudes and in deeper waters. Fish richness also increased with latitude, but exhibited a hump-shaped relationship with depth, increasing with depth up to the continental shelf break, ~200 m depth, and then decreasing in deeper waters. We found relationships between fish taxonomic and functional diversity and latitude, depth, substrate, and time at the regional scale, but not at the coast-wide scale, suggesting that coast-wide patterns can obscure important correlates at smaller scales. Our study provides insight into complex diversity patterns of the deep water soft substrate benthic ecosystems off the US West Coast.

Substrate rugosity and temperature matters: patterns of benthic diversity at tropical intertidal reefs in the SW Atlantic

“…In benthic marine communities, substrate and oceanographic parameters are critical predictors of the distribution and abundance of species, setting biodiversity patterns at multiple spatio-temporal scales and shaping observed biodiversity patterns (Menge et al, 1997;Wieters, Broitman & Branch, 2009;Burrows, Harvey & Robb, 2008;Blanchette et al, 2008;Griffiths et al, 2017). The strength of regulating factors at each location is linked to ecosystem dynamics (Navarrete et al, 2005), incorporating both local (e.g., substrate, productivity) and large-scale climatic and oceanographic conditions (e.g., Steneck & Dethier, 1994;Menge et al, 2003;Zawada, Piniak & Hearn, 2010;Piacenza et al, 2015;Mazzuco et al, 2019). On rocky shores, wave exposition and changes in sea temperature are major factors structuring and regulating benthic communities at multiple scales (e.g., Burrows, Harvey & Robb, 2008;Blanchette et al, 2008).…”

Bio‐physical models of marine environments reveal biases in the representation of protected areas

“…Additionally, levels of species diversity will vary significantly according to benthic substrate, with harder substrates often associated with higher diversity (i.e. rocky or coral reef) due to a greater habitat complexity and stability than softer substrates (Piacenza et al, ). Combining multiple variables known to be associated with species distribution into a Bio‐physical model can provide a detailed assessment of how well an MPA system (a collection of MPAs within a jurisdiction) represents the spectrum of marine ecosystems, and whether protection is well matched to areas of high biodiversity.…”

Genomics of habitat choice and adaptive evolution in a deep-sea fish

“…W hile longitudinal and latitudinal habitat transitions have been proposed to define marine communities and promote intraspecific differentiation [1][2][3] , little is known about the importance of transitions along ocean depth gradients 4,5 , although substantial changes in species assemblages with depth have been recorded (for example, ref. 6 ), and relatively narrow depth ranges may distinguish closely related species (for example, refs 7,8 ).…”