Search

Wood in the deep sea serves as a substantial food source in an otherwise barren environment, forming specialized, endemic, and diverse community assemblages. This biodiversity reliance on a terrestrial source creates a linkage by which anthropogenic impacts on land can alter the deep oceans. Knowledge of the alpha- or beta-diversity of entire wood-fall communities, and wooden drivers of each would elucidate the terrestrial and deep-sea linkage. We report on a multifactorial experiment in the deep ocean in which alpha- and beta-diversity of 43 wood falls and 11 tree species are quantified over time, wood density, and wood size. We tested multiple hypotheses seeking to link how biodiversity on land may impact the biodiversity in the deep oceans. A tremendous biodiversity occurred among these wood falls in the deep Gulf of Mexico; 114 invertebrate species from 10 phyla. Time, wood hardness, and wood size all impacted various components of community structure. In many cases, these effects were additive. Species occurring on softwoods versus hardwoods and small versus large wood falls were compositionally different. Although various processes can control community structure, this experiment suggests a strong influence of environmental filtering and host specificity of wood-fall invertebrates suggesting an intimate coupling to tree biodiversity and biomass on land., (© 2023 The Ecological Society of America.)

Climate change is shifting community structure and biodiversity on a global scale, in part due to alterations of chemical and thermal energy availability. These changes may impact ecosystem functioning through their influence on functional diversity. We investigate patterns of functional diversity, functional niches, and functional traits in bivalve communities across the energetic gradient of the deep Atlantic Ocean. We use the functional traits feeding type, tiering, and motility level to define the axes of functional space and the unique combinations of these traits as functional niches. We find that increased energy affords new species, added into functional space through niche expansion rather than niche packing. Underlying this pattern are complex dynamics of gains and losses of individual functional niches, with few adapted to the low- and high-energy extremes, and most occurring at intermediate energy. Adaptive qualities of specific traits are evidenced by those functional niches occurring at energetic extremes. Tradeoffs between these traits within the intermediate energy zone underlie an increased coexistence of functional niches, which in turn drives a unimodal pattern of functional niches and expansion of used functional space. This work suggests that energy-limited communities may be especially vulnerable to continued shifts in food availability through the Anthropocene.

Body size of life on the Earth spans many orders of magnitude, and with it scales the energetic requirements of organisms. Thus, changes in environmental energy should impact community body-size distributions in predictable ways by reshaping ecological and niche dynamics. We examine how carbon, oxygen and temperature, three energetic drivers, impact community size-based assembly in deep-sea bivalves. We demonstrate that body-size distributions are influenced by multiple energetic constraints. Relaxation in these constraints leads to an expansion of body-size niche space through the addition of novel large size classes, increasing the standard deviation and mean of the body-size distribution. With continued Anthropogenic increases in temperature and reductions in carbon availability and oxygen in most ocean basins, our results point to possible radical shifts in invertebrate body size with the potential to impact ecosystem function.