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Landscape structure and land use affects estuarine benthic invertebrates in the Virginian Biogeographic Province, USA
Citation:
Pelletier, Peg, A. Gold, J. Copeland, L. Gonzalez, AND P. August. Landscape structure and land use affects estuarine benthic invertebrates in the Virginian Biogeographic Province, USA. New England Estuarine Research Society (NEERS) Fall Meeting, New Bedford, MA, October 25 - 27, 2018.
Impact/Purpose:
A watershed is the area of land that drains into an estuary. This study was conducted to look for relationships between estuary condition and watershed characteristics. Watershed characteristics included the type of land use as well as the size of the watershed and its associated estuary. Estuary condition was assessed using benthic invertebrates (small organisms living in the bottom of estuaries). To be included in the study, a small estuary had to contain at least three sampling locations to capture differences in the estuary; previous studies had only used one location to characterize the entire system. We looked at land use in the entire watershed, as well as the land use near streams, but found that for this study, these were closely related. We also found that land use closer to the estuary was not more closely related to estuary condition than land use further away from the estuary. This was probably because land use types were found throughout the watersheds rather than exclusively along the coast or high up in the watershed. We found that estuarine area and watershed area, which are unchanging aspects of the system, were the most important variables used to predict estuary condition and should be considered when planning restoration projects. In addition, land use in the watershed (development, agriculture) were also associated with negative impacts and should be considered.
Description:
Estuaries are dynamic transition zones linking freshwater and oceanic habitats. These productive ecosystems are threatened by a variety of stressors including human modification of coastal watersheds. In this study we examined potential linkages between estuarine condition and the watershed using landscape condition attributes and benthic invertebrate communities. We sought to determine if the spatial arrangement of watershed attributes was important in predicting benthic invertebrate condition. We examined attributes at the watershed scale as well as those associated with riparian areas. We also examined whether attributes closer to the estuary were more strongly related to benthic invertebrate condition. Since riparian and watershed variables were highly correlated at the biogeographic province scale, either riparian or watershed variables were adequate for assessing estuarine invertebrate condition. Modeling estuarine condition indicated that inherent landscape structure (e.g., estuarine area and watershed area) is important to predicting benthic invertebrate condition and needs to be considered in the context of watershed/ estuary planning and restoration. As shown in other studies, anthropogenic geospatial attributes (development, agriculture) are associated with adverse impacts. Previous studies demonstrated the importance of land use closer to the estuary, but this relationship was not observed in this study, perhaps due to the watershed heterogeneity in our study area.