Spatiotemporal variability in the structure of seagrass meadows and associated macrofaunal assemblages in southwest England (UK): Using citizen science to benchmark ecological pattern

Abstract

Seagrass meadows underpin a variety of ecosystem services and are recognized as globally important habitats and a conservation priority. However, seagrass populations are currently impacted by a range of biotic and abiotic stressors, and many are in decline globally. As such, improved understanding of seagrass populations and their associated faunal assemblages is needed to better detect and predict changes in the structure and functioning of these key habitats. Here, we analyzed a large dataset—collected by recreational scuba divers volunteering on a citizen science project—to examine spatiotemporal patterns in ecological structure and to provide a robust and reliable baseline against which to detect future change. Seagrass ( Zostera marina ) shoot density and the abundance of associated faunal groups were quantified across 2 years at 19 sites nested within three locations in southwest UK, by collecting in situ quadrat samples (2,518 in total) during 328 dives. Seagrass shoot density and meadow fragmentation was comparable across locations but was highly variable among sites. Faunal abundance and assemblage structure varied between areas with or without seagrass shoots; this pattern was largely consistent between locations and years. Overall, increased seagrass density was related to increased faunal abundance and explained shifts in faunal assemblage structure, although individual faunal groups were affected differently. More broadly, our study shows that well‐funded and orchestrated citizen science projects can, to some extent, gather fundamental information needed to benchmark ecological structure in poorly studied nearshore marine habitats.

Environment predicts seagrass genotype, phenotype, and associated biodiversity in a temperate ecosystem

“…This study uses (1) novel seagrass population genetic data ( Supplementary material ), (2) seagrass phenotype and associated fauna data freely available as supplementary material associated with Smale et al (2019) , and (3) environmental data obtained from the European Marine Observation and Data Network (EMODnet) seabed habitats portal 1 and Copernicus Marine Environment Monitoring Service. 2…”

“…Seventeen locations were assessed along a c. 300 km stretch of the south coast of England ( Figure 1 ). These sites were selected at random from a larger pool ( Smale et al, 2019 ). Survey locations were situated c. 1–5 m depth (see Figure 1 ).…”

“…Surveys were conducted by trained volunteer divers during August of 2016 and 2017 as part of the Community Seagrass Initiative (CSI), a citizen science project led by the National Marine Aquarium and contributing partners, funded by the United Kingdom Heritage Lottery Fund. Full survey details are published in Smale et al (2019) . Seagrass presence/absence, as well as shoot density, was estimated by placing 15 quadrats (0.25 m 2 ) along each of a series of predefined transects, parallel to the shore, varying between 50 and 150 m, dependent upon the size of the seagrass meadow.…”

“…Abundance of nine faunal groups were also assessed within these quadrats: ascidians, bryozoans, cnidarians, crustaceans, echinoderms, fish, molluscs, sponges, and worms. The emphasis was on broad taxonomic classification that could be reliably identified by trained volunteers ( Smale et al, 2019 ). While this simplification did not allow for a robust quantification of biodiversity, it did allow for many samples to be collected across large spatial scales with a high degree of confidence.…”

The Verification of Ecological Citizen Science Data: Current Approaches and Future Possibilities

“…There may, however, be schemes that do not consider verification, trusting the recorders' abilities to report species correctly (Wiggins et al 2011). This may be justifiable if schemes specifically recruit knowledgeable volunteers (Gardner 2019) or provide training to volunteers before surveying (Smale et al 2019). Some citizen science schemes focus recording effort on selected days annually (Chase and Levine 2016).…”