An environmental stress model correctly predicts unimodal trends in overall species richness and diversity along intertidal elevation gradients

Abstract

Environmental stress is a major factor structuring communities. An environmental stress model (ESM) predicts that overall species richness and diversity should follow a unimodal trend along the full stress gradient along which assemblages from a regional biota can occur (not to be confused with the intermediate disturbance hypothesis, which makes predictions only for basal species along an intermediate-to-high stress range). Past studies could only provide partial support for ESM predictions because of the limited stress range surveyed or a low sampling resolution. In this study, we measured overall species richness and diversity (considering all seaweeds and invertebrates) along the intertidal elevation gradient on two wave-sheltered rocky shores from Helgoland Island, on the NE Atlantic coast. In intertidal habitats, tides cause a pronounced gradient of increasing stress from low to high elevations. We surveyed up to nine contiguous elevation zones between the lowest intertidal elevation (low stress) and the high intertidal boundary (high stress). Nonlinear regression analyses revealed that overall species richness and diversity followed unimodal trends across elevations on the two studied shores. Therefore, our study suggests that the ESM might constitute a useful tool to predict local richness and diversity as a function of environmental stress. Performing tests on other systems (marine as well as terrestrial) should help to refine the model.

Wave‐induced changes in seaweed toughness entail plastic modifications in snail traits maintaining consumption efficacy

“…Both are common species on NW and NE Atlantic rocky shores, including our study sites (Scrosati & Heaven ; Zwerschke et al . ). First, we tested the hypothesis (i) that thalli of F. vesiculosus from wave‐exposed habitats are more resistant to puncture (proxy for tissue toughness) than thalli from wave‐sheltered habitats.…”

Metabolic cold adaptation and aerobic performance of blue mussels (Mytilus edulis) along a temperature gradient into the High Arctic region

“…Physiological optimization to a life at low temperatures involves protein modification, as well as adjustments in enzyme activity, making cold-adapted species or populations more sensitive to increasing temperatures compared to their warmer counterparts (Nielsen et al 1999;DoucetBeaupre et al 2010;Zwerschke et al 2013). Another possible side effect of living in a cold, thermally stable environment is a reduced ability to (physiologically) cope with acute or chronic temperature variation (Somero and Devries 1967;Peck et al 2009b).…”

Interhemispheric comparison of scale‐dependent spatial variation in the structure of intertidal rocky‐shore communities

“…The daily alternation of high and low tides determines a sharp increase in abiotic stress related to changes in temperature, desiccation, irradiance, and osmotic potential from low to high elevations. Such environmental variation, directly or indirectly (through changes in interspecific interactions), ultimately causes vertical zonation patterns in which species replace one another across intertidal elevations (Menge and Branch 2001, Harley and Helmuth 2003, Benedetti-Cecchi et al 2006, Scrosati and Heaven 2007, Zwerschke et al 2013.…”