Methods for Image-based Surveys of Benthic Macroinvertebrates and Their Habitat Exemplified by the Drop Camera Survey for the Atlantic Sea Scallop.

Underwater imaging has long been used in the field of marine ecology but decreasing costs of high-resolution cameras and data storage have made the approach more practical than in the past. Image-based surveys allow for initial samples to be revisited and are non-invasive compared to traditional survey methods that typically involve nets or dredges. Protocols for image-based surveys can vary greatly but should be driven by target species behavior and survey objectives. To demonstrate this, we describe our most recent methods for an Atlantic sea scallop (Placopecten magellanicus) drop camera survey to provide a procedural example and representative results. The procedure is divided into three critical steps that include survey design, data collection, and data products. The influence of scallop behavior and the survey goal of providing an independent assessment of the U.S. sea scallop resource on the survey procedure are then discussed in the context of generalizing the method. Overall, the broad applicability and flexibility of the University of Massachusetts Dartmouth School for Marine Science and Technology (SMAST) drop camera survey demonstrates the method could be generalized and applied to a variety of sessile invertebrates or habitat focused research.

Identification of persistent benthic assemblages in areas with different temperature variability patterns through broad-scale mapping.

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.

Bait and the susceptibility of American lobsters Homarus americanus to epizootic shell disease.

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.