Marine biodiversity and ecosystem functioning: what’s known and what’s next?

Abstract

Marine ecosystems are experiencing rapid and pervasive loss of species.Understanding the consequences of species loss is critical to effectively managing these systems. Over the last several years, numerous experimental manipulations of 25 species richness have been performed, yet existing quantitative syntheses have focused on a just a subset of processes measured in experiments and, as such, have not summarized the full data available from marine systems. Here, we present the results of a meta-analysis of 174 marine experiments from 42 studies that have manipulated the species richness of organisms across a range of taxa and trophic 30 levels and analysed the consequences for various ecosystem processes (categorised as production, consumption or biogeochemical fluxes).Our results show that, generally, mixtures of species tend to enhance levels of ecosystem function relative to the average component species in monoculture, but have no or negative effect on functioning relative to the 'highest-performing' species. 35These results are largely consistent with those from other syntheses, and extend conclusions to ecological functions that are most commonly measured in the marine realm (e.g. nutrient release from sediment bioturbation). For experiments that manipulated three or more levels of richness, we attempted to discern the functional form of the BEF relationship. We found that, for response variables categorised as 40 consumption, a power-function best described the relationship, which is also consistent with previous findings. However, we identified a linear relationship between richness and production. Combined, our results suggest that losses of species will, on average, tend to alter the functioning of marine ecosystems. We outline several research frontiers that will allow us to more fully understand how, why, and 45 when diversity may drive the functioning of marine ecosystems.

Can we predict ecosystem functioning using tightly linked functional gene diversity?

“…This is due to niche complementarity, positive interactions or the higher chance of including high-performing species (Tilman et al, 2014). The qualitative trend has been consistent with that hypothesis across a variety of systems (Schmid et al, 2009;Cardinale et al, 2011;Gamfeldt et al, 2015), including microbial ecosystems (Bell et al, 2005;Philippot et al, 2013;Delgado-Baquerizo et al, 2016). Papers in the field hence frequently include verbal predictions that future loss of diversity will have adverse consequences for ecosystem services and human well being .…”

Biodiversity effects of the predation gauntlet

“…Of course, there are also additional biological and socio-economic concerns associated with the lionfish invasion that extend beyond biodiversity effects. Biodiversity can be associated with ecosystem functioning, productivity, and evolutionary dynamics in marine systems (Gamfeldt et al 2015). The studies synthesized here offer key insights into how mesopredators affect prey fish abundance and biodiversity and, more broadly, the role mesopredators play in driving spatio-temporal variation in reef-fish biodiversity.…”

Changes in the location of biodiversity–ecosystem function hot spots across the seafloor landscape with increasing sediment nutrient loading

“…This has resulted in a call for more relevance to realworld situations and realistic field experiments embracing natural spatial patterns and variation in community composition [9][10][11]. Nevertheless, evidence is accumulating of important and positive BEF relationships, particularly as the space and time scale of experiments are extended and increasing numbers of species are incorporated into the research [12][13][14]. This suggests that spatial changes in biodiversity or environmental characteristics within ecological landscapes will affect functional performance.…”