Coastal Habitats as Surrogates for Taxonomic, Functional and Trophic Structures of Benthic Faunal Communities

Abstract

Due to human impact, there is extensive degradation and loss of marine habitats, which calls for measures that incorporate taxonomic as well as functional and trophic aspects of biodiversity. Since such data is less easily quantifiable in nature, the use of habitats as surrogates or proxies for biodiversity is on the rise in marine conservation and management. However, there is a critical gap in knowledge of whether pre-defined habitat units adequately represent the functional and trophic structure of communities. We also lack comparisons of different measures of community structure in terms of both between- (β) and within-habitat (α) variability when accounting for species densities. Thus, we evaluated a priori defined coastal habitats as surrogates for traditional taxonomic, functional and trophic zoobenthic community structure. We focused on four habitats (bare sand, canopy-forming algae, seagrass above- and belowground), all easily delineated in nature and defined through classification systems. We analyzed uni- and multivariate data on species and trait diversity as well as stable isotope ratios of benthic macrofauna. A good fit between habitat types and taxonomic and functional structure was found, although habitats were more similar functionally. This was attributed to within-habitat heterogeneity so when habitat divisions matched the taxonomic structure, only bare sand was functionally distinct. The pre-defined habitats did not meet the variability of trophic structure, which also proved to differentiate on a smaller spatial scale. The quantification of trophic structure using species density only identified an epi- and an infaunal unit. To summarize the results we present a conceptual model illustrating the match between pre-defined habitat types and the taxonomic, functional and trophic community structure. Our results show the importance of including functional and trophic aspects more comprehensively in marine management and spatial planning.

Epifaunal diversity patterns within and among seagrass meadows suggest landscape‐scale biodiversity processes

“…, Törnroos et al. ). Yet, how exactly these habitats support such highly productive animal assemblages, and the role of spatial arrangement of habitats, remains poorly understood (Boström et al.…”

“…This pattern suggests that compositional differences among meadows, one form of beta diversity, could be high and a relatively important component of seagrass‐associated biodiversity within meadows (Törnroos et al. , Socolar et al. , Boyé et al.…”

“…In highly diverse coastal marine habitats, we nearly always lack basic information about where and when species occur (Aylesworth et al 2017) and the spatial scales over which dominant diversity-influencing processes operate (Gaston 2000, Bostr€ om et al 2006. Coastal foundation species (sensu Dayton 1972) such as seagrass and kelp are often targeted for conservation for the biodiversity they harbor and the ecosystem services they provide (Byers et al 2006, Crain and Bertness 2006, Halpern et al 2007, T€ ornroos et al 2013). Yet, how exactly these habitats support such highly productive animal assemblages, and the role of spatial arrangement of habitats, remains poorly understood (Bostr€ om et al 2011).…”

“…Meadows often contain a subset of species than are found in the regional species pool, suggesting that there is some persistent constraint on how many species a meadow hosts at any one time (Barnes and Ellwood 2012, Barnes 2013a, Boy e et al 2017. This pattern suggests that compositional differences among meadows, one form of beta diversity, could be high and a relatively important component of seagrass-associated biodiversity within meadows (T€ ornroos et al 2013, Socolar et al 2016, Boy e et al 2017. Though studies of seagrass faunal diversity have reported high species turnover at moderate spatial scales (<150 m; Ellwood 2012, Barnes 2013b), few studies specifically assess beta diversity at the same scale (but see Boy e et al 2017).…”

Biogeographic assessments: A framework for information synthesis in marine spatial planning

“…Simultaneously, the diversity and geographical scope of mapped socio-economic data has also increased [6,13]. The development of reliable and cost-effective spatial models has been aided by identification of useful surrogates or proxies for complex spatial patterns that are difficult to map directly, such as species distributions, ecological function, and ecosystem service values [51,76,87]. Significant progress has also been made in data sharing through institutional contributions to open access data portals and the broadening of public participation in data collection (i.e., citizen science and crowd sourcing) [11,86,30].…”