Sowing the Seeds of Seagrass Recovery Using Hessian Bags

Richard K F Unsworth,Christopher Lowe,Benjamin L Jones,Leanne C Cullen-Unsworth,Hanna K Nuuttila,Richard Lilley,Chiara M Bertelli,Samuel C Rees,Nicole Esteban

doi:10.3389/fevo.2019.00311

Richard K F Unsworth, Christopher Lowe + Show 7 more

Open Access

https://doi.org/10.3389/fevo.2019.00311

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Abstract

Seagrass meadows are an important wetland habitat that have been degraded globally but have an important carbon storage role. In order to expand the restoration of these productive and biodiverse habitats methods are required that can be used for large scale habitat creation across a range of environmental conditions. The spreading of seagrass seeds has been proven to be a successful method for restoring seagrass around the world, however in places where tidal range is large such methods become limited by resultant water movements. Here we describe and test a method for deploying seagrass seeds of the species Zostera marina over large scales using a new, simple method “Bags of Seagrass Seeds Line (BoSSLine).” This method involved planting seeds and sediment using natural fiber hessian bags deployed along strings anchored onto the seabed. When deployed in a suitable environment 94% of bags developed mature seagrass shoots, unfortunately one site subjected to a large storm event resulted in sediment burial of the bags and no seed germination. Bags were filled with 100 seeds with each leading to the development of 2.37 ± 2.41 mature shoots (206 ± 87 mm in length) 10 months after planting. The method was proven successful however the experiments illustrated the need to ensure habitat suitability prior to their use. Low seed success rate was comparable to other restoration studies, however further trials are recommended to ensure ways to improve this rate. In conclusion, this study provides evidence for an effective, simple method “Bags of Seagrass Seeds Line (BoSSLine)” for deploying seeds of the seagrass Zostera marina over large scales.

Highlights

Seagrass meadows provide critically important ecosystem services to our planet, including the storage of carbon (Fourqurean et al, 2012; Röhr et al, 2018), supporting world fisheries production (Unsworth et al, 2018), and amongst many other things, helping prevent beach erosion (James et al, 2019)
Two pilot Proof of Concept (PoC) studies on seagrass “seed bag” use were conducted, one at Porthdinllaen in North Wales and the other in the Helford River, Cornwall (Figure 4). These PoC studies trialed the use of differing types of seed bags under various deployment methods
Sea surface temperatures typically range from 8 to 17 degrees C. During this project we confirmed the location of a small patch of seagrass (Zostera marina) previously recorded in 1958 by Martin George (Kay, 1998) in Dale (51.704765◦N, 5.159228◦W)

Summary

Introduction

Seagrass meadows provide critically important ecosystem services to our planet, including the storage of carbon (Fourqurean et al, 2012; Röhr et al, 2018), supporting world fisheries production (Unsworth et al, 2018), and amongst many other things, helping prevent beach erosion (James et al, 2019). Seagrass meadows have long been considered the “ugly duckling” of marine conservation (Duarte et al, 2008), the urgent and unprecedented changes that are required to avoid a climate change catastrophe mean that a dual need for conservation of existing meadows, Seagrass Seed Bag Restoration and the active restoration of previously extirpated seagrass meadows, are emerging as potentially meaningful climate change mitigation strategies (Duarte et al, 2013). This is due to the high rates at which seagrass meadows store carbon. Seagrass conservation and restoration practices are coming of age and with it so is the need for improved methods in all potential seagrass environments

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