Understanding the Effects of Marine Biodiversity on Communities and Ecosystems

TLDR

Marine biodiversity changes influence community properties and ecosystem processes—including nutrient cycling, productivity, stability, and trophic transfer—and research is converging with terrestrial studies to guide future cross‑habitat investigations. The authors review marine experiments that manipulate species, genotype, or functional group richness to assess biodiversity effects. The review finds that diversity often has a modest impact on primary production but consistently reduces community variability and enhances resistance or recovery, while diverse prey assemblages are more resilient to top‑down control, use resources more completely, and boost consumer fitness, though predator diversity can either strengthen or weaken top‑down effects depending on omnivory and predator interactions.

Abstract

There is growing interest in the effects of changing marine biodiversity on a variety of community properties and ecosystem processes such as nutrient use and cycling, productivity, stability, and trophic transfer. We review published marine experiments that manipulated the number of species, genotypes, or functional groups. This research reveals several emerging generalities. In studies of primary producers and sessile animals, diversity often has a weak effect on production or biomass, especially relative to the strong effect exerted by individual species. However, sessile taxon richness did consistently decrease variability in community properties, and increased resistance to, or recovery from disturbance or invasion. Multitrophic-level studies indicate that, relative to depauperate assemblages of prey species, diverse ones (a) are more resistant to top-down control, (b) use their own resources more completely, and (c) increase consumer fitness. In contrast, predator diversity can either increase or decrease the strength of top-down control because of omnivory and because interactions among predators can have positive and negative effects on herbivores. Recognizing that marine and terrestrial approaches to understanding diversity-function relationships are converging, we close with suggestions for future research that apply across habitats.