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

Seagrass meadows underpin a variety of ecosystem services and are
recognised 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 analysed 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 was quantified across 2 years at 19
sites nested within 3 locations in southwest UK, by collecting in situ
quadrat samples (2518 in total) during 328 dives. Seagrass shoot density
and meadow fragmentation was comparable across locations but was highly
variable amongst 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.