Gauging wetland restoration status using benthic-based structural and functional metrics
Abstract
Description
Efforts to restore Bahia Grande, a 2630 hectare, historically sea grass dominated
playa lake, are currently underway and describing its current ecological status is critical
to recommending any future physical manipulations to the immense basin. A benthic
community based study was conducted on three estuaries in Cameron County, Texas
(2012 to 2013) in order to compare the polychaete community dynamics and ecosystem
productivity rates of the restored basin to that of two older adjacent reference sites (i.e.
South Bay and San Martin Lake) in an effort to gauge system status. All three sites were
once contiguous with the Lower Laguna Madre and remain in close proximity yet differ
in degree of anthropogenic disturbances and biological and physical environments.
Benthic core sediment samples and water quality parameters were retrieved quarterly
along with monthly aquatic and ambient temperature and oxygen data. Additionally, data
loggers were deployed at each site two weeks per month for one year. Net Ecosystem
Metabolism (NEM) rates were determined by generating diel oxygen curves adjusted for
wind-diffusion. PERMANOVA analysis of abundance data revealed significant
difference by site, quarter, and by an interaction between site and quarter. Further
investigation of assemblages using SIMPER revealed different species were driving the
site dissimilarities. Physical differences between the systems were largely due to varying
levels of salinity and dissolved oxygen as exhibited by PCA ordination. PERMDISP
revealed that Bahia Grande undergoes higher temporal variability than the reference sites,
which is considered to be an indication of instability. Bahia Grande appears to be
trending similarly in terms of ecosystem metabolism however, the basin is functioning
differently in terms of production and respiration. Bahia Grande currently hosts a
community that is temporally variable and highly dominant with low diversity, and low
productivity. Recommendations supporting future manipulations to increase tidal flow
and freshwater input, thus lowering hydraulic residence time and potentially increasing
recruitment are strongly suggested based on the findings of this study.
PDF; 54 pgs.
PDF; 54 pgs.
Keywords
Bahia Grande (Tex.), Restoration ecology--Texas--Bahia Grande--Case studies, Restoration ecology--Texas--Cameron County--Case studies, Wetland restoration--Texas--Bahia Grande--Case studies, Wetland restoration--Texas--Cameron County--Case studies, Wetland restoration--Monitoring--Texas--Bahia Grande--Case studies, Wetland restoration--Monitoring--Texas--Cameron County--Case studies, Community metabolism, Macrobenthos