Tolley S.G.,Florida Gulf Coast University |
Brosious B.B.,Passarella and Associates Inc |
Peebles E.B.,University of South Florida
Estuaries and Coasts | Year: 2013
Oyster reefs provide structural habitat for resident crabs and fishes, most of which have planktonic larvae that are dependent upon transport/retention processes for successful settlement. High rates of freshwater inflow have the potential to disrupt these processes, creating spatial gaps between larval distribution and settlement habitat. To investigate whether inflow can impact subsequent recruitment to oyster reefs, densities of crab larvae and post-settlement juveniles and adults were compared in Estero Bay, Florida, over 22 months (2005-2006). Three species were selected for comparison: Petrolisthes armatus, Eurypanopeus depressus, and Rhithropanopeus harrisii. All are important members of oyster reef communities in Southwest Florida; all exhibit protracted spawning, with larvae present throughout the year; and each is distributed unevenly on reefs in different salinity regimes. Recruitment to oyster reefs was positively correlated with bay-wide larval supply at all five reefs examined. Species-specific larval connectivity to settlement sites was altered by inflow: where connectivity was enhanced by increased inflow, stock-recruitment curves were linear; where connectivity was reduced by high inflows, stock-recruitment curves were asymptotic at higher larval densities. Maximum recruit density varied by an order of magnitude among reefs. Although live oyster density was a good indicator of habitat quality in regard to crab density, it did not account for the high variability in recruit densities. Variation in recruit density at higher levels of larval supply may primarily be caused by inflow-induced variation in larval connectivity, creating an abiotic simulation of what has widely been regarded as density dependence in stock-recruitment curves. © 2013 Coastal and Estuarine Research Federation.
Tolley S.G.,Florida Gulf Coast University |
Brosious B.M.,Passarella and Associates Inc |
Evans III J.T.,City of Sanibel |
Nelson J.L.,Florida Gulf Coast University |
And 4 more authors.
Journal of Shellfish Research | Year: 2012
Planktonic larvae of resident, oyster reef-associated decapods and fishes are subject to variable transport and retention whenever estuarine circulation is altered by freshwater inflow. Because freshwater inflow has the potential to advect larvae either toward or away from oyster reef settlement habitats, we compared the monthly distributions and abundances of larvae and postsettlement stages in Estero Bay, FL, under variable inflows during a 2-y period. Positive correlations between inflow and larval abundances of 2 species (Rhithropanopeus harrisii and Gobiesox strumosus) appeared to be caused by advection of upstream larvae downstream into the study area, whereas similar correlations with postsettlement juveniles of other species (Eurypanopeus depressus and Petrolisthes armatus) suggested bottom-up improvements to postsettlement survival. In contrast, the larvae of many species were advected seaward and away from oyster reef habitats during periods of elevated inflow, creating a spatial gap between the larvae and their landward settlement habitat. The size of this gap was larger for reefs that had greater exposure to freshwater inflows. Larvae displaced too far seaward would have a reduced window of opportunity to find oyster substrate for settlement, thus risking increased aberrant drift and predation loss. Because of the stationary nature of the settlement habitat, advection associated with elevated freshwater inflows was beneficial to some species and detrimental to others, producing winners and losers. The study also suggested that live oyster density was a good indicator of the density, biomass, and richness of oyster reef fishes and decapods. Evidence of temporal resource partitioning (successive peaks in larval densities) was present for those fishes that use empty oyster shell as sites for egg laying and nesting, although this pattern was present only during the first year of the study.
Dixon A.D.,Passarella and Associates Inc |
Cox W.R.,Passarella and Associates Inc |
Everham III E.M.,Florida Gulf Coast University |
Ceilley D.W.,Florida Gulf Coast University
Southeastern Naturalist | Year: 2011
The Picayune Strand Restoration Project is being conducted as part of the Comprehensive Everglades Restoration Plan to restore hydrology and habitat in Southwest Florida. This study evaluated the success of the restoration activities by examining anuran species richness and relative abundance in relation to various restoration treatments, which included restored areas, un-restored areas, and natural wetlands. Anuran observations were conducted using nocturnal audible call surveys and dip netting. Univariate results indicated that: the lowest species richness and relative abundance values occurred within the un-restored areas, richness significantly increased in all restored areas relative to un-restored areas, abundance increased in some restored areas but not others, and highest richness and abundance were documented in the natural wetlands. Multivariate analysis confirmed these patterns and also indicated that the anuran species assemblages were significantly different between restoration treatments. Furthermore, the presence or absence of Lithobates sphenocephalus utricularius (Southern Leopard Frog), Gastrophryne carolinensis (Eastern Narrow-mouthed Toad), and Hyla femoralis (Pine Woods Treefrog) may be used to document restoration success or hydrologic disturbance, respectively. These findings suggest that the restoration activities can be effective and that anurans could be used as performance measures of restoration success.