Most states in the U.S. are currently developing methods for assessing the integrity of aquatic habitats through the development of regional biocriteria. While multimetric indices have been used to show community composition, pollution tolerance, species diversity, and trophic structure with a combined index, the specific environmental factors that drive biological communities may be better explained through the use of multivariate statistical techniques. Macroinvertebrate and fish assemblages were sampled along with water quality, landuse and qualitative and quantitative habitat assessments from forty-nine sites throughout the Choctawhatchee-Pea, a southeastern U.S. watershed. Multivariate statistical analyses of habitat, water quality, and land-use data were used to determine the relationship between environmental variables and the dependent biological variables, macroinvertebrate and fish community structure. Sampling of biological and environmental data showed that there was a great deal of homogeneity within the watershed, which complicated the task of identifying environmental influences on biological assemblages. Macro-invertebrate and fish assemblages of the Choctawhatchee-Pea watershed were similar in their response to environmental conditions with water chemistry having the greatest relationship to macro-invertebrate and fish community structure followed by instream habitat and land use.
Activities such as agriculture, silviculture, and mining contribute nonpoint pollution to Alabama's streams through polluted runoff and excessive sedimentation. Highly erodible soils characteristic of the Choctawhatchee‐Pea Rivers watershed, combined with intense rainfall and land use practices, contribute large amounts of sediment to streams. Biological monitoring can reflect the acute impacts of pollutants as well as prolonged effects of habitat alteration, and development of biological criteria is important for the establishment of enforceable laws regarding nonpoint source pollution. Macroinvertebrates were collected from 49 randomly selected sites from first through sixth‐order streams in the Choctawhatchee‐Pea Rivers watershed and were identified to genus level. Thirty‐eight candidate metrics were examined, and an invertebrate community index (ICI) was calibrated by eliminating metrics that failed to separate impaired from unimpaired streams. Each site was scored with those metrics, and narrative scores were assigned based on ICI scores. Least impacted sites scored significantly lower than sites impacted by row crop agriculture, cattle, and urban land uses. Conditions in the watershed suggest that the entire area has experienced degradation through past and current land use practices. An initial validation of the index was performed and is described. Additional evaluations of the index are in progress.
Augmentative biocontrol, defined as the use of indigenous natural enemies to control pest populations, has not been explored extensively in marine systems. This study tested the potential of the anemone Anthothoe albocincta as a biocontrol agent for biofouling on submerged artificial structures. Biofouling biomass was negatively related to anemone cover. Treatments with high anemone cover (>35%) led to significant changes in biofouling assemblages compared to controls. Taxa that contributed to these changes differed among sites, but included reductions in cover of problematic fouling organisms, such as solitary ascidians and bryozoans. In laboratory trials, A. albocincta substantially prevented the settlement of larvae of the bryozoan Bugula neritina when exposed to three levels of larval dose, suggesting predation as an important biocontrol mechanism, in addition to space pre-emption. This study demonstrated that augmentative biocontrol using anemones has the potential to reduce biofouling on marine artificial structures, although considerable further work is required to refine this tool before its application.
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