Metabolic Niches and Biodiversity: A Test Case in the Deep Sea Benthos

Craig R Mcclain,S River Dixon,James A Nelson,Seth Finnegan,Thomas J Webb,Clifton C Nunnally

doi:10.3389/fmars.2020.00216

Abstract

The great anthropogenic alterations occurring to carbon availability in the oceans necessitates an understanding of the energy requirements of species and how changes in energy availability may impact biodiversity. The deep oceans are characterized naturally by extremely low availability of chemical energy and are particularly vulnerable to changes in carbon flux from surface waters. Because the energetic requirements of an organism impact nearly every aspect of their ecology and evolution, we hypothesize that species are adapted to specific levels of carbon availability and occupy a particular metabolic niche. We test this hypothesis in deep-sea invertebrates specifically examining how energetic demand, axes of the metabolic niche, and geographic range size vary over gradients of chemical energy availability. We find that species with higher energetic expenditures, and ecologies associated with high energy demand, are located in areas with higher chemical energy availability. In addition, we find that range size and location of deep-sea species is determined by geographic patterns in chemical energy availability. Our findings indicate that deep-sea species are adapted to specific energy regimes, the metabolic niche can potentially link scales from individuals to ecosystems, and link adaptation to patterns in biogeography and biodiversity.

Highlights

As demonstrated by several environmental indicators anthropogenic impacts on the environment continue to exhibit a long-term, post-industrial rise (Steffen et al, 2015)
We propose an eco-evolutionary adaptive theory of the metabolic niche (Wilson et al, 2011) where species are adapted to specific energy regimes which scale with biodiversity patterns
We examine this relationship between geographic range size, as a proxy for niche width, and mean particulate organic carbon (POC) across the geographic range for gastropod species across the Atlantic Ocean

Summary

Introduction

As demonstrated by several environmental indicators anthropogenic impacts on the environment continue to exhibit a long-term, post-industrial rise (Steffen et al, 2015) This human induced environmental degradation has led to significant declines in global biodiversity including increasing numbers of endangered species and decreasing abundances of key taxa (Lotze et al, 2006; Butchart et al, 2010). We hypothesize that the species observed in a locality are dependent on the energy content of that habitat We develop this hypothesis through a series of 10 linked propositions, from first principles of metabolic ecology through to biogeographic patterns in metabolic adaptation. For each of these propositions, we review current support and theory from a general eco-evolutionary viewpoint and with a deep-sea perspective. For many of the propositions, we bring new data from deepsea, benthic invertebrates to bear to quantify and test the hypotheses

Methods

Findings

Conclusion