Temporal and spatial differences between taxonomic and trait biodiversity in a large marine ecosystem: Causes and consequences

Abstract

Biodiversity is a multifaceted concept, yet most biodiversity studies have taken a taxonomic approach, implying that all species are equally important. However, species do not contribute equally to ecosystem processes and differ markedly in their responses to changing environments. This recognition has led to the exploration of other components of biodiversity, notably the diversity of ecologically important traits. Recent studies taking into account both taxonomic and trait diversity have revealed that the two biodiversity components may exhibit pronounced temporal and spatial differences. These apparent incongruences indicate that the two components may respond differently to environmental drivers and that changes in one component might not affect the other. Such incongruences may provide insight into the structuring of communities through community assembly processes, and the resilience of ecosystems to change. Here we examine temporal and spatial patterns and drivers of multiple marine biodiversity indicators using the North Sea fish community as a case study. Based on long-term spatially resolved survey data on fish species occurrences and biomasses from 1983 to 2014 and an extensive trait dataset we: (i) investigate temporal and spatial incongruences between taxonomy and trait-based indicators of both richness and evenness; (ii) examine the underlying environmental drivers and, (iii) interpret the results in the context of assembly rules acting on community composition. Our study shows that taxonomy and trait-based biodiversity indicators differ in time and space and that these differences are correlated to natural and anthropogenic drivers, notably temperature, depth and substrate richness. Our findings show that trait-based biodiversity indicators add information regarding community composition and ecosystem structure compared to and in conjunction with taxonomy-based indicators. These results emphasize the importance of examining and monitoring multiple indicators of biodiversity in ecological studies as well as for conservation and ecosystem-based management purposes.

Four decades of functional community change reveals gradual trends and low interlinkage across trophic groups in a large marine ecosystem

“…To our knowledge, this is the first study comparing long‐term trends and multi‐decadal dynamics in multiple dimensions of functional community change across trophic groups and areas. Previous trait‐based studies on long‐term functional community change have focused on single organism groups separately, either zoobenthos (Gogina, Darr, & Zettler, ; Neumann & Kröncke, ; Veríssimo et al, ; Weigel, Blenckner, & Bonsdorff, ) or fish (Baptista, Martinho, Nyjtrai, Pardal, & Dolbeth, ; Barcelo, Ciannelli, Olsen, Johannessen, & Knutsen, ; Dencker et al, ; Frelat et al, ), and particularly multi‐trait compositional changes on local scale (Clare, Robinson, & Frid, ; Frid & Caswell, ).…”

Fish communities diverge in species but converge in traits over three decades of warming

“…In recent decades, ocean warming has profoundly impacted marine fish communities (Cheung, Watson, & Pauly, ; Flanagan, Jensen, Morley, & Pinsky, ; Fossheim et al, ; Wernberg et al, ). Examining spatial and temporal changes in fish communities under warming can provide insight into ecological responses to climate change, and how ecosystem structure may change in the future (Auber, Travers‐Trolet, Villanueva, & Ernande, ; Beukhof, Dencker, Pecuchet, & Lindegren, ; Dencker et al, ). Additionally, observational studies can provide robust results for understanding community dynamics and improving predictive models (Mouillot, Graham, Villéger, Mason, & Bellwood, ; Suding et al, ).…”

“…Over the last few decades, and especially in recent years, trait-based approaches have been shown superior to taxonomic approaches for examining community assembly and ecosystem functioning (Lavorel & Garnier, 2002;Mouillot, Graham, et al, 2013;Pecuchet et al, 2017;Sakschewski et al, 2016;Weiher & Keddy, 1995). Yet, examining changes in taxonomic and trait diversity simultaneously may best describe community dynamics (Dencker et al, 2017;Monnet et al, 2014;Villéger, Miranda, Hernández, & Mouillot, 2010). For instance, changes in species composition may not lead to changes in trait diversity if loser species are replaced by species with similar traits (Clare, Robinson, & Frid, 2015;Villéger et al, 2010;White, Montgomery, Storchová, Hořák, & Lennon, 2018).…”

A morphometric dive into fish diversity

“…, Dencker et al. ). As expected, we observed that areas with high species richness were more likely to present a higher morphological richness.…”

“…, Dencker et al. ; Appendix : Text S1). Finally, we compared the morphological distance (Euclidean pairwise distances of images calculated from coordinates on the first three PCs) with the taxonomical distance calculated with five taxonomic levels (Appendix : Text S1).…”