Individual study: Restoration of native oysters in a highly invaded estuary
Zabin C.J., Wasson K. & Fork S. (2016) Restoration of native oysters in a highly invaded estuary. Biological Conservation, 202, 78-87
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Restore biogenic habitats (other methods) - Restore oyster reefs
A replicated, controlled study in 2013–2015 of 12 restored reefs in the Mission-Aransas estuary, southern coast of Texas, USA (Graham et al. 2017) found that the effects of restoring reefs of eastern oyster Crassostrea virginica on oysters and reef-associated organisms, after 21 months, depended on the material used. After 21 months, the community structure of combined invertebrates and fish differed with material (data presented as a graphical analysis). The diversity of mobile organisms (fish, crabs and shrimps) was similar across material (reported as a diversity index). Oysters dominated the cover of sessile organisms on all reefs, but cover was lower on river rock (41%) compared to all other material (68–53%). Oyster abundance was higher on concrete (1,020/m2), than limestone (940/m2), oyster shell (830/m2), and river rock (600/m2). Crabs (five species combined) dominated the mobile organisms across reefs, with no effect of material on their abundance (270–440/m2). Crab biomass was higher on oyster shell (53 g/m2) and concrete (38 g/m2) than river rock (24 g/m2), but not limestone (36 g/m2). Shrimps (five species combined) were more abundant on oyster shell (140/m2) than any other material (60–120/m2). Shrimp biomass was similar on all material (3–6 g/m2). In 2013, twelve oyster reefs (152 m3) were constructed with either concrete, river rocks, limestones, or oyster shells (3 reefs/material). After three months, six trays filled with 19 L of matching material were deployed at each reef. Quarterly, one tray/reef was retrieved and mobile organisms (> 4mm) identified, counted, and dry-weighed. Oysters were counted, and their percentage cover assessed. In addition, other sessile invertebrates were assessed, and a benefit-cost ratio for each material was calculated (see paper).
(Summarised by Anaëlle Lemasson)