Articles by Kevin D. E. Stokesbury in JoVE
Methods for Image-based Surveys of Benthic Macroinvertebrates and Their Habitat Exemplified by the Drop Camera Survey for the Atlantic Sea Scallop N. David Bethoney1, Kevin D. E. Stokesbury1 1School for Marine Science and Technology, University of Massachusetts Dartmouth Image based surveying is an increasingly practical, non-invasive method to sample the marine environment. We present the protocol of a drop camera survey that estimates the abundance and distribution of the Atlantic sea scallop (Placopecten magellanicus). We discuss how this protocol can be generalized for application to other benthic macroinvertebrates.
Other articles by Kevin D. E. Stokesbury on PubMed
Measuring Fish Abundance in a Weir Trap Using an Acoustical-optical Platform The Journal of the Acoustical Society of America. | Pubmed ID: 17902877 Data recorded by a bottom mounted survey platform deployed within the opening of a fishing weir were used to calculate species specific abundance estimates for comparison to the weir catch. Abundance estimates were calculated from the combination of sonar and video information recorded by the Acoustical-Optical Platform (AOP). Echo counting was used to detect individual moving targets in the sonar images with the application of a background removal technique utilizing a moving average filter. Video images provided species identification of acoustic targets. Video images and differences in target strength distributions reflected a change in dominant species from each deployment which was confirmed with the weir catch. The algorithm used to calculate AOP abundance estimates was most accurate in predicting abundance for species comprising at least 13% of the overall catch by weight. Close agreement between the species specific AOP estimates and absolute abundances of each species suggests that the combination of acoustic and video data is a powerful combination for accurately identifying fish species and predicting abundance.
Bait and the Susceptibility of American Lobsters Homarus Americanus to Epizootic Shell Disease Diseases of Aquatic Organisms. | Pubmed ID: 21797030 Shell disease (SD) has been observed in lobster populations for almost a hundred years, but recently, rates of an epizootic form of shell disease (ESD) have increased in the southern New England (USA) area. A large proportion of fish in the diet of American lobsters Homarus americanus has been linked to increased rates of SD. Therefore, the use of fish as lobster bait may be linked to increased ESD rates in lobsters. Lobsters from the western portion of Martha's Vineyard, MA (41 degrees N, 71 degrees W), were randomly divided into 3 groups of 16 and exposed to dietary treatments (100% herring; 48% crab, 48% blue mussel and 4% plant matter; or 50% herring, 24% crab, 24% mussel, 2% plant matter) to determine if lobster tissue delta15N levels reflected diet. The results of the feeding experiment confirmed that differences in diet are observed in the delta15N levels of lobster muscle tissue. The delta15N levels of tissue samples from 175 wild lobsters with varying degrees of ESD were unrelated to ESD severity but did indicate lobsters were eating large amounts of fish (bait). This result does not support the speculation that fish used as bait is contributing to ESD outbreaks in portions of the southern New England area.
Identification of Persistent Benthic Assemblages in Areas with Different Temperature Variability Patterns Through Broad-scale Mapping PloS One. | Pubmed ID: 28489873 Ecosystem-based management is a place-based approach that considers the relationships between system parts. Due to the complexity of ecosystems in the marine environment it is often difficult to define these relationships in space and time. Maps illustrate spatial concepts. Here we promote ecosystem-based spatial thinking by layering datasets from a larger project that mapped benthic fauna, substrate characteristics, and oceanic conditions on monthly, annual and decadal time scales along the U.S. continental shelf. By combining maps of persistent benthic megafauna and bottom temperature variability over approximately 90,000 km2, we identified wide spread benthic animal assemblages and regional disparity in temperature variability. From a broad-scale perspective the locations of the assemblage appear to be related to sea scallop population dynamics and indicate potential regional differences in climate change resiliency. These findings offer information on a scale that correlates with marine spatial planning, and could be used as a starting point for further investigation. To spur additional analysis and facilitate their linkage to other datasets, these datasets are available through public, online data portals. Overall, this study demonstrates how the growth of maps from single to multiple elements can help promote and facilitate the multifactor, ecosystem-based thinking needed to support regional ocean planning.