Eelgrass meadows return to Frenchy's Cove, Anacapa Island: recovery ten years after successful transplantation
A large eelgrass (Zostera pacifica) meadow was present at Frenchy’s Cove, Anacapa Island, prior to the late 1980s. Extensive grazing by white sea urchins (Lytechinus anamesus) in the late 1980s eliminated the meadow by 1991, when a 60-m transect (10-m depth) was established; no natural recovery was...
| Main Authors: | , , , , , |
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| Format: | Text |
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BYU ScholarsArchive
2014
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| Online Access: | https://scholarsarchive.byu.edu/mwnan/vol7/iss1/35 https://scholarsarchive.byu.edu/context/mwnan/article/1070/viewcontent/34262.pdf |
| Summary: | A large eelgrass (Zostera pacifica) meadow was present at Frenchy’s Cove, Anacapa Island, prior to the late 1980s. Extensive grazing by white sea urchins (Lytechinus anamesus) in the late 1980s eliminated the meadow by 1991, when a 60-m transect (10-m depth) was established; no natural recovery was observed from 1991 to 2002. In 2002, approximately 450 eelgrass shoots were transplanted to Frenchy’s Cove from 2 large meadows at Santa Cruz Island (Smugglers Cove, Prisoners Harbor), and a second transect (7-m depth) was established in 2004. Shoot planting densities ranged from 0.11 m–2 to 11 m–2. Meadow dimensions, shoot density and reproductive status, along with density and species abundance of associated benthic invertebrates and fishes were surveyed annually along each transect from 2003 to 2012. Densities of white urchins remained low, thereby facilitating expansion of the meadow via vegetative growth and seedling recruitment. Individual patches eventually coalesced into an overall meadow at Frenchy’s Cove of 0.87 ha in 2009, retracting slightly to 0.62 ha in 2012. Shoot density reached a mean of 108 m–2 in 2009 and ranged from 23 m–2 to 90 m–2 in 2012, comparable to natural meadows at nearby Santa Cruz Island. Increased diversity and abundance of invertebrates and fishes were evident, with an average of 5 (2001), 9 (2005), and 14 (2011) fish species recorded during 30-minute surveys and a dramatic shift in fish guilds, with black perch, pile perch, and halfmoon only associated with the new meadow. As a result of the initial 2002 eelgrass transplantation, eelgrass meadows returned to northern Anacapa Island; and by 2012, they expanded along nearly 3 km of nearshore sandy habitat. A diverse biotic assemblage is becoming reestablished at Frenchy’s Cove and adjacent shallow sandy substrates along the north side of Middle Anacapa Island.Antes de finales de la década de 1980, existía un extenso campo de zosteras marinas (Zostera pacífica) en Frenchy’s Cove (Cala Frenchy en Isla Anacapa). Hacia finales de los ... |
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