Guidelines for the study of the epibenthos of subtidal environments

These Guidelines for the Study of the Epibenthos of Subtidal Environments document a range of sampling gears and procedures for epibenthos studies that meet a variety of needs. The importance of adopting consistent sampling and analytical practices is highlighted. Emphasis is placed on ship‐based techniques for surveys of coastal and offshore shelf environments, but diver‐assisted surveys are also considered

International Year of Planet Earth 5. Applications of Seafloor Mapping on the Canadian Atlantic Continental Shelf

Canada’s final mapping frontier is its offshore territory. Compared to Canada’s landmass, only a limited portion of Canada’s seafloor has been mapped using the modern technology of multi-beam sonar. Where this high-resolution mapping technique has been applied on Canada’s Atlantic continental margin, insight has been gained into the studies of seafloor habitat mapping, Quaternary history and sea-level change, sediment bedforms and dynamics, and seafloor conditions for in-stream tidal power. Seafloor habitat mapping in Canada provides the knowledge base to effectively manage offshore fisheries, evaluate marine protected areas, minimize the environmental impact of offshore development, and resolve seafloor-use conflicts. Multibeam sonar mapping has revealed a complex glacial landsystem developed on the Canadian Atlantic continental shelf and supports the concept of the late glacial maximum reaching the shelf edge. The application of multibeam sonar technology offers unprecedented images of bedform geomorphology and this knowledge is crucial to understanding sediment mobility and its effect on seafloor habitat, engineering, and infrastructure. To minimize the risk to engineering infrastructure on the seabed, planning of tidal-energy developments in regions of large tidal range requires detailed information about the water depth, seafloor substrate and sediment mobility, and long-term seabed change garnered using multibeam sonar mapping techniques. SOMMAIRE L’ultime frontière de la cartographie du Canada est son territoire extracôtier. Par rapport à son territoire continental, seule une faible portion du territoire extracôtier canadien a été cartographié par la technique moderne d’imagerie sonar multifaisceaux. Là où cette technique de cartographie de haute résolution a été utilisée sur la marge continentale canadienne atlantique, on a pu faire des progrès dans l’étude de cartographie d’habitat du fond marin, de l’histoire quaternaire des fluctuations du niveau de la mer, de la morphologie des couches et de la dynamique sédimentaires, ainsi que des caractéristiques du fond marin en vue de l’installation de centrales marémotrices. La cartographie d’habitat du fond marin permet de constituer une base de connaissances nécessaires pour gérer efficacement la pêche hauturière, établir la valeur des zones marines protégées, minimiser les incidences environ-nementales des activités de mise en valeur extracôtières, et résoudre les conflits d’utilisation des fonds marins. La cartographie par imagerie sonar multifaisceaux a montré qu’un système complexe de terres émergées s’est développé sur le plateau continental atlantique du Canada et qui correspond au concept d’un maximum glaciaire ayant atteint la limite du plateau continental. L’utilisation de la technologie sonar multifaisceaux permet d’obtenir des images sans précédents de la morphologie des dépôts, et ces connaissances sont cruciales pour comprendre la mobilité des sédiments et les répercussions sur l’habitat du fond marin, les aménagements et les infrastructures. Dans le but de minimiser les risques sur les infrastructures installées sur le fond marin, la planification d’installations marémotrices en zones de marées à grandes variations exige des informations détaillées sur la profondeur d’eau, la nature du fond marin et la mobilité des sédiments, ainsi que sur les changements à longs termes obtenues par l’utilisation de technique de cartographie sonar multifaisceaux

Estimates Of Sea Scallop (Placopecten Magellanicus) Incidental Mortality From Photographic Multiple Before-After-Control-Impact Surveys

After several decades of stock decline, the Atlantic sea scallop ( Placopecten magellanicus) resource has rebounded to become one of the most valuable fisheries in the United States. The continued sustainability of this fishery is supported by catch limits determined by annual stock projection models. Incidental mortality is an important term in these projection models, but is historically difficult to measure. Current estimates are derived from field experiments that relied heavily on qualitative observations and as a result are based on limited data with low precision. To better quantify incidental mortality, a multiple before-after-control-impact experimental design was used to measure the effect of scallop dredging on the disposition of sea scallops that remain uncaptured on the seafloor following dredging. An autonomous underwater vehicle was used to collect color photographs and side-scan sonar images of the seafloor before and after controlled dredge treatments in the mid-Atlantic and Georges Bank regions. Approximately 170,000 photographs were annotated for instances of mortality. Dredge-induced incidental mortality of 2.5% and 8% was estimated for the mid-Atlantic Bight and Georges Bank sites, respectively, a difference that is likely attributable to the relatively harder substrate of the scallop habitat on Georges Bank that results in greater physical trauma to the uncaptured scallops. This study provides a quantitative estimate of incidental mortality using a noninvasive platform that offers precise mission navigation for repeated surveys. The spatial scale and distribution of the study sites are broad relative to past incidental mortality studies, and the substrate types at each are common in the sea scallop fishery. Estimated mortality rates are lower than the values currently used in fishery stock models and suggest the existing values are conservative, but likely appropriate estimates for management purposes

Benthic habitat mapping in coastal waters of south–east Australia

The Victorian Marine Mapping Project will improve knowledge on the location, spatial distribution, condition and extent of marine habitats and associated biodiversity in Victorian State waters. This information will guide informed decision making, enable priority setting, and assist in targeted natural resource management planning. This project entails benthic habitat mapping over 500 square kilometers of Victorian State waters using multibeam sonar, towed video and image classification techniques. Information collected includes seafloor topography, seafloor softness and hardness (reflectivity), and information on geology and benthic flora and fauna assemblages collectively comprising habitat. Computerized semi-automated classification techniques are also being developed to provide a cost effective approach to rapid mapping and assessment of coastal habitats.Habitat mapping is important for understanding and communicating the distribution of natural values within the marine environment. The coastal fringe of Victoria encompasses a rich and diverse ecosystem representative of coastal waters of South-east Australia. To date, extensive knowledge of these systems is limited due to the lack of available data. Knowledge of the distribution and extent of habitat is required to target management activities most effectively, and provide the basis to monitor and report on their status in the future.<br /

The dredge fishery for scallops in the United Kingdom (UK) : effects on marine ecosystems and proposals for future management

The king scallop fishery is the fastest growing fishery in the UK and currently the second most valuable. The UK is also home to the largest queen scallop fishery out of all of Europe. However, concerns have been raised about the effects of this recent growth of UK scallop fisheries among scientists and conservation bodies, as well as amongst the public following recent media campaigns (e.g. Hugh’s Fish Fight). This is because the majority of scallop landings (95%) are made by vessels towing scallop dredges, a type of fishing gear known to cause substantial environmental impacts. In addition, several scallop stocks are showing signs of overexploitation and there is concern over future impacts of ocean warming and acidification. Although, there have been several recent improvements in the management of scallop fisheries in parts of the UK, information on many scallop stocks around the UK is still lacking. This report therefore proposes that better monitoring and stock assessments are needed for these scallop fisheries and stocks. With recent legislation soon to result in the development of a new network of marine protected areas (MPAs) around the UK, and improved management of fisheries in European Marine Sites, now is a crucial time to review the UK scallop dredge fishery and its impacts on the wider environment so that this new legislation can support a sustainable future for the UK scallop fishery. This report was therefore commissioned by the Sustainable Inshore Fisheries Trust with the aim of collating existing knowledge on the management and environmental impacts of scallop fisheries around the UK

Sessile and mobile components of a benthic ecosystem display mixed trends within a temperate marine reserve

Despite recent efforts to increase the global coverage of marine protected areas (MPAs), studies investigating the effectiveness of marine protected areas within temperate waters remain scarce. Furthermore, out of the few studies published on MPAs in temperate waters, the majority focus on specific ecological or fishery components rather than investigating the ecosystem as a whole. This study therefore investigated both the dynamics of benthic communities as well as fish populations within a recently established, fully protected marine reserve in Lamlash Bay, Isle of Arran, United Kingdom, over a four year period. A combination of photo and diver surveys revealed live maerl (Phymatolithon calcareum), macroalgae, sponges, hydroids, feather stars and eyelash worms (Myxicola infundibulum) to be significantly more abundant within the marine reserve than on surrounding fishing grounds. Likewise, the overall composition of epifaunal communities in and outside the reserve was significantly different. Both results are consistent with the hypothesis that protecting areas from fishing can encourage seafloor habitats to recover. In addition, the greater abundance of complex habitats within the reserve appeared to providing nursery habitat for juvenile cod (Gadus morhua) and scallops (Pecten maximus and Aequipecten opercularis). In contrast, there was little difference in the abundance of mobile benthic fauna, such as crabs and starfish, between the reserve and outside. Similarly, the use of baited underwater video cameras revealed no difference in the abundance and size of fish between the reserve and outside. Limited recovery of these ecosystem components may be due to the relatively small size (2.67 km2) and young age of the reserve (< 5 years), both of which might have limited the extent of any benefits afforded to mobile fauna and fish communities. Overall, this study provides evidence that fully protected marine reserves can encourage seafloor habitats to recover, which in turn, can create a number of benefits that flow back to other species, including those of commercial importance