Rehabilitating Seagrass by Facilitating Recruitment: Improving Chances for Success

Abstract

Attempts to arrest seagrass loss through numerous rehabilitation methods have traditionally produced inconsistent results. On Australia's southern coast, hessian bags made from biodegradable jute fibers show promise for rehabilitating Amphibolis antarctica by facilitating recruitment of seedlings in situ. Testing ways to improve the performance of bags (i.e. increasing seagrass recruitment and establishment) showed that bags with a coarse outer weave of hessian facilitated greater seedling densities (approximately 1700 individuals/m 2 ) than bags with a fine outer weave, but the content of bags (sand vs. sand and rubble mixture) had little effect. Isolated bags facilitated greater longer term densities than bags grouped together, while similar densities were sampled up to 80 m away from a natural meadow. Lastly, bags that had spent less time in situ initially facilitated more recruits than older bags, but longer term (21-32 months) retention was similar among bag ages. Collectively, the results suggest hessian bags can be a relatively simple, cost-effective, and environmentally friendly method for rehabilitating Amphibolis seagrass, with few considerations in their use other than their physical architecture and arrangement (e.g. isolated coarse-weave bags).

Habitat restoration: Early signs and extent of faunal recovery relative to seagrass recovery

“…Restoration of this site began as a trial of new techniques to facilitate the natural recruitment of A. antarctica seedlings, with the overall intention of re-establishing an extensive continuous seagrass meadow (see Irving et al 2010;Wear et al 2010;Irving et al 2013;Tanner 2014). As a result, restoration plots are replicated temporally rather than spatially.…”

“…antarctica seedlings (Irving et al 2013). While not formally measured due to the small size of the entire site (~ 2 km between the edge of the seagrass and shoreline, Wear et al 2010) there were no obvious environmental gradients present.…”

“…antarctica seedlings to become established and create new patches (Irving et al 2013), which have persisted for > 5 years (Tanner 2014). Amphibolis is a large perennial structure-forming seagrass that grows in similar environments to Posidonia (Shepherd & Womersley 1981;Bryars & Rowling 2009).…”

‘Bright spots’ for estuary management in temperate Southern Australia

“…46 This improved water quality has been beneficial for seagrass recovery efforts. Between 1949 and 2007, this coastline experienced a net loss of 6200 hectares of seagrass 47 influencing the quality and quantity of ecosystem service delivery. Prior to 2005, local rehabilitation trials by South Australian scientists demonstrated effective methods to improve the spatial extent and health of seagrass meadows.…”

Seagrass rehabilitation off metropolitan Adelaide: a case study of loss, action, failure and success

“…Most of these trials have been published separately (Seddon ; Irving et al . , ; Wear et al . ; Tanner ), but here, we set the trials within their management context and draw implications for future research and management.…”