Reef restoration facilitates habitat provisioning for oysters and motile epifauna
Abstract
Severe degradation of oyster reef habitat over the past century has led to associated losses
in ecological and economic benefits. Common oyster reef restoration goals target replacement of
lost ecosystem services, including habitat provision, by replacing the ecological functions of lost
reef habitats. The goal of this study was to monitor development of faunal communities on a
restored oyster reef in the Gulf of Mexico. In July 2017, more than 1 M tons of reclaimed oyster
shell were used to restore 1.83 ha of oyster reef complex (~610 linear m) in St. Charles Bay,
Texas. Oysters, epifauna, and infauna were sampled monthly for the first three months after
construction, and then were sampled quarterly for a total of 19 months at the restored reef and
nearby reference sites. Within the first three months after construction, mean oyster densities
increased by more than three times, growth rates peaked at 0.41 mm d-1
, and the restored oyster
population shifted from 100 % spat to more than 90 % submarket size oysters. Although
Perkinsus marinus infection was detected on every sampling date on the reference reef, only a
single infected oyster was observed on the restored reef. Reef location—away from infected
source populations— and other hydrological factors such as current speed and direction, may
have impeded disease development. Epifaunal density, biomass, and diversity, became similar to
that of the reference reef within four months after construction, but a shift in epifaunal
community assemblages occurred between the first and the second year after construction,
indicating monitoring periods of more than one year are necessary to capture faunal community
development on a restored reef. The structure provided by the restored reef was conducive to
oyster and epifaunal community development and may have supported ecological resistance
since minimal impacts to reef structure were observed in the wake of Hurricane Harvey. Infaunal
density, diversity, and biomass did not differ between sites adjacent (less than 5 m) versus distant
(~30 m) from the restored reef and were governed more by salinity than presence of the restored
reef. The recruitment and densities of oysters indicate that the restored reef met proposed success
metrics within 19 months after construction, and that restored reefs can successfully replace
ecosystem services, such as habitat provision, lost due to degradation.