Caffrey J.M.,University of West Florida |
Murrell M.C.,U.S. Environmental Protection Agency |
Amacker K.S.,University of West Florida |
Harper J.W.,Apalachicola Bay National Estuarine Research Reserve |
And 3 more authors.
Estuaries and Coasts | Year: 2014
Measurements of primary production and respiration provide fundamental information about the trophic status of aquatic ecosystems, yet such measurements are logistically difficult and expensive to sustain as part of long-term monitoring programs. However, ecosystem metabolism parameters can be inferred from high frequency water quality data collections using autonomous logging instruments. For this study, we analyzed such time series datasets from three Gulf of Mexico estuaries: Grand Bay, MS; Weeks Bay, AL; and Apalachicola Bay, FL. Data were acquired from NOAA's National Estuarine Research Reserve System Wide Monitoring Program and used to calculate gross primary production (GPP), ecosystem respiration (ER), and net ecosystem metabolism (NEM) using Odum's open water method. The three systems represent a diversity of estuaries typical of the Gulf of Mexico region, varying by as much as two orders of magnitude in key physical characteristics, such as estuarine area, watershed area, freshwater flow, and nutrient loading. In all three systems, GPP and ER displayed strong seasonality, peaking in summer and being lowest during winter. Peak rates of GPP and ER exceeded 200 mmol O2 m-2 day-1 in all three estuaries. To our knowledge, this is the first study examining long-term trends in rates of GPP, ER, and NEM in estuaries. Variability in metabolism tended to be small among sites within each estuary. Nitrogen loading was highest in Weeks Bay, almost two times greater than that in Apalachicola Bay and 35 times greater than to Grand Bay. These differences in nitrogen loading were reflected in average annual GPP rates, which ranged from 825 g C m-2 year-1 in Weeks Bay to 401 g C m-2 year-1 for Apalachicola Bay and 377 g C m-2 year-1 in Grand Bay. Despite the strong inter-annual patterns in freshwater flow and salinity, variability in metabolic rates was low, perhaps reflecting shifts in the relative importance of benthic and phytoplankton productivity, during different flow regimes. The advantage of the open water method is that it uses readily available and cost-effective sonde monitoring technology to estimate these fundamental estuarine processes, thus providing a potential means for examining long-term trends in net carbon balance. It also provides a historical benchmark for comparison to ongoing and future monitoring focused on documenting the effect of human activities on the coastal zone. © 2013 The Author(s).
Rush S.A.,University of Georgia |
Mordecai R.,University of Georgia |
Woodrey M.S.,Mississippi State University |
Woodrey M.S.,Grand Bay National Estuarine Research Reserve |
Cooper R.J.,University of Georgia
Waterbirds | Year: 2010
Loss and modification of tidal marsh habitat has contributed to the decline of marsh bird species. For many marsh birds that inhabit tidal ecosystems, little information exists on habitat use, particularly in relation to movement and response to prey availability. In this study, radio-telemetry was used to investigate home range size, movement patterns and response of Clapper Rails (Rallus longirostris) to prey availability within tidal marshes in coastal Mississippi. Mean fixed kernel 95% home range for breeding Clapper Rails was 1.37 ha ± SE 0.27 (N = 10 birds) with a 50% core use area 0.32 ha ± SE 0.07 (N = 10 birds), which are estimates similar to those obtained throughout this species' range. The extent of Clapper Rail movements during the incubation period was negatively correlated with density of fiddler crab burrows within 50 m of nest sites. Clapper Rails' use of marsh edge decreased relative to tidal height. Use of this habitat type may have been further restricted during the first few weeks of the parental-care period when adults were caring for recently fledged young. Collectively these results illustrate the importance of edge and interior marsh habitats and may provide an explanation for the variation in Clapper Rail densities found within and between tidal marsh systems.
David A.T.,University of Washington |
Simenstad C.A.,University of Washington |
Cordell J.R.,University of Washington |
Toft J.D.,University of Washington |
And 2 more authors.
Estuaries and Coasts | Year: 2015
During the transition of juveniles from fresh water to estuarine and coastal environments, the survival of Pacific salmon (Oncorhynchus spp.) can be strongly size selective and cohort abundance is partly determined at this stage. Because quantity and quality of food influence juvenile salmon growth, high rates of prey and energy acquisition during estuarine residence are important for survival. Human activities may have affected the foraging performance of juvenile salmon in estuaries by reducing the area of wetlands and by altering the abundance of salmon. To improve our understanding of the effects of wetland loss and salmon density on juvenile salmon foraging performance and diet composition in estuaries, we assembled Chinook salmon (Oncorhynchus tshawytscha) diet and density data from nine US Pacific Northwest estuaries across a gradient of wetland loss. We evaluated the influence of wetland loss and density on juvenile Chinook salmon instantaneous ration and energy ration, two measures of foraging performance, and whether the effect of density varied among estuaries with different levels of wetland loss. We also assessed the influence of wetland loss and other explanatory variables on salmon diet composition. There was no evidence of a direct effect of wetland loss on juvenile salmon foraging performance, but wetland loss appeared to mediate the effect of density on salmon foraging performance and alter salmon diet composition. Specifically, density had no effect on foraging performance in the estuaries with less than 50 % wetland loss but had a negative effect on foraging performance in the estuaries with greater than 50 % wetland loss. These results suggest that habitat loss may interact with density to constrain the foraging performance of juvenile Chinook salmon, and ultimately their growth, during a life history stage when survival can be positively correlated with growth and size. © 2015 Coastal and Estuarine Research Federation
David A.T.,University of Washington |
Goertler P.A.L.,University of Washington |
Munsch S.H.,University of Washington |
Jones B.R.,University of Washington |
And 8 more authors.
Estuaries and Coasts | Year: 2016
Compared to benthic and water-column invertebrate assemblages, considerably less is known about terrestrial arthropods inhabiting estuarine wetlands despite their importance to tidal wetland biodiversity and productivity. We also need to know more about how human modification of estuaries, including efforts to restore estuarine wetlands, affects these assemblages. To address this knowledge gap, we assembled data from multiple studies on terrestrial arthropod assemblages from 87 intertidal wetland sites in 13 estuaries along the west coast of North America. Arthropods were sampled between 1998 and 2013 with fallout traps deployed in wetlands for 1 to 3 days at a time. We describe patterns in the abundance and taxonomic composition of terrestrial arthropods and evaluate the relative ability of natural and anthropogenic factors to explain variation in abundance and composition. Arthropod abundance was highly variable. Vegetation assemblage, precipitation, and temperature best explained variation in arthropod abundance, while river discharge, latitude, and developed and agricultural land cover surrounding sampling sites were less important. Arthropod abundance rapidly achieved levels of reference wetlands after the restoration of tidal influence to leveed wetlands, regardless of surrounding land cover. However, arthropod assemblage composition was affected by the amount of developed land cover as well as restoration age. These results suggest that restoration of tidal influence to leveed wetlands can rapidly restore some components of estuarine wetland ecosystems but that recovery of other components will take longer and may depend on the extent of anthropogenic modification in the surrounding landscape. © 2016 Coastal and Estuarine Research Federation
Rush S.A.,University of Windsor |
Olin J.A.,University of Windsor |
Fisk A.T.,University of Windsor |
Woodrey M.S.,Mississippi State University |
And 2 more authors.
Estuaries and Coasts | Year: 2010
Much of North America's tidal marsh habitat has been significantly altered by both natural and man-made processes. Thus, there is a need to understand the trophic ecology of organisms endemic to these ecosystems. We applied carbon (δ13C) and nitrogen (δ15N) stable isotope analysis, along with isotope mixing models, to egg yolk, liver, and muscle tissues of clapper rails (Rallus longirostris) and their likely prey items. This analysis enabled us to explore variation in trophic niche and diet composition in this important marsh bird in two northern Gulf of Mexico tidal marshes that are river and ocean-dominated. For the river-associated estuary, δ13C and δ15N of egg yolks, liver, and pectoral muscle tissue samples provided evidence that clapper rails maintained a similar diet during both the winter and the breeding season. A trophic link between C3 primary productivity and the clapper rail's diet was also indicated as the δ13C of clapper rail egg yolks related negatively with the aerial cover of C3 macrophytes. Clapper rails from the ocean-dominated estuary had a narrower trophic niche and appeared to be utilizing marine resources, particularly, based on modeling of liver stable isotope values. Variation in stable isotope values between egg yolk and liver/muscle in both systems suggests that endogenous resources are important for egg production in clapper rails. These results demonstrate that diet composition, prey source, and niche width of clapper rails can vary significantly across different estuaries and appear to be influenced by hydrological conditions. © 2010 Coastal and Estuarine Research Federation.