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Truchon S.,Royal Dutch Shell | Brzuzy L.,Royal Dutch Shell | Fonseca M.,CSA Ocean science Inc.
Society of Petroleum Engineers - SPE E and P Health, Safety, Security and Environmental Conference - Americas 2015 | Year: 2015

Hard substrate associated with offshore oil and gas platforms can contribute to the productivity of marine ecosystems thereby generating local and regional economic benefits. These benefits form the basis for incorporating the platform into a rigs-to-reefs program when it is retired or selecting some other type of removal option. There are many options for reefing platforms, each differing in environment impact of activities associated with the dismantling and transport of the platform structure (deck, jacket, and other subsea structures). Utilizing science-based decision making in exploring platform removal options can be beneficial for all stakeholders in the context of a regulatory environment, complex ecosystem, and human interactions across multiple scales. Accomodating these complexities in a decision making process is the foundation of an Ecosystem Based Management (EBM) approach. EBM is an environmental management approach that recognizes the full array of interactions within an ecosystem, including humans, rather than considering single issues, species, or ecosystem services in isolation (Christensen et al., 1996; McLeod et al., 2005; Altman et al., 2011). The focus of this study is on one of Shell's deepwater assets in the Gulf of Mexico. The fixed jacket platform has been in operation for more than 35 years and extends to over 1,000 feet of water depth of the coast of Louisiana. Few studies have been published on the ecology of marine life inhabiting deepwater platforms such as these. To begin to understand the specific contribution of this platform as an artificial reef, a stratified (across depth down the platform) study was performed using routinely collected Remotely Operated Vessel (ROV) video footage to assess fish and sessile biotic communities. The results of the ROV study revealed clear depth-related patterns for visually conspicuous epibiota (Lophelia pertusa) as well as numerous species of reef and pelagic fishes. These data were used to construct a matrix to rank ecosystem services with respect to several decommissioning alternatives, including: complete removal of the deck and jacket; removal of the deck and topping the jacket (to below 85 feet below the waterline) and leaving it in place; and removal of the deck, and transferring the entire jacket to a rigs-to-reef location. This portion of the assessment provided a strategic framework for identifying and evaluating sensitive ecosystem services in association with both human and environmental drivers to provide realistic (actionable) guidance in the selection of these decommissioning options. The ranking illustrated that a high level of ecosystem services could be maintained by decommissioning alternatives that leave the jacket in place or as part of a rigs-to-reefs program. Copyright 2015, Society of Petroleum Engineers. Source


Butler M.J.,Old Dominion University | Tiggelaar J.M.,Old Dominion University | Tiggelaar J.M.,CSA Ocean science Inc. | Shields J.D.,Virginia Institute of Marine Science
Journal of Experimental Marine Biology and Ecology | Year: 2014

Blue crabs (Callinectes sapidus) living in high salinity regions along the Atlantic and Gulf coasts of the United States are subject to infection by the parasitic dinoflagellate Hematodinium perezi with a prevalence that can exceed 50%. Infections are usually lethal, thus H. perezi infection represents a significant cause of mortality in many crab populations. Most studies of this host-parasite interaction have focused on epidemiology, host-pathogen dynamics, and pathogen transmission; little is known about the impact of the parasite on host behavior and population dynamics. We examined the effects of H. perezi on blue crab mortality from predation, activity patterns, and habitat use. Infected crabs suffered significantly higher predation than uninfected crabs when tethered in the field. Similarly, infected juvenile crabs were preyed upon significantly more often than uninfected conspecifics when exposed to a predatory adult crab in laboratory experiments. Laboratory experiments also revealed that the behavior of infected and uninfected crabs differed in ways that affected their risk of predation. Compared to infected crabs, uninfected juvenile crabs buried more frequently, moved less, and used oyster shell substrate more often when a predator was present. These differences do not appear to be driven by olfactory cues because chemosensory assays show that H. perezi infections do not affect detection of juvenile crabs by adult crabs, nor infected juvenile crab chemosensory responses to adult crabs. Our results indicate that H. perezi infection alters crab behavior in ways that enhance predatory culling of infected crabs, and this in turn may limit the spread of the parasite. © 2014 Elsevier B.V. Source


Currin C.,National Oceanic and Atmospheric Administration | Davis J.,National Oceanic and Atmospheric Administration | Baron L.C.,National Oceanic and Atmospheric Administration | Baron L.C.,National Park Service | And 3 more authors.
Journal of Coastal Research | Year: 2015

Aerial photography was used to determine rates of shoreline change in the New River Estuary (NRE), North Carolina, from 1956 to 2004. The NRE shoreline was digitized from aerial photographs taken in 1956, 1989, and 2004, and shoreline type was determined by ground-truthing the entire shoreline by small boat in 2009. Major shoreline type categories included swamp forest (6% of total), salt marsh (21%), sediment bank (53%), and modified/hardened (19%). Ground-truthing provided additional details on relief, marsh species composition, and structure type. A point-based, end-point rate approach was used to measure shoreline change rate (SCR) at 50 m intervals for the periods 1956-89, 1989-2004, and 1956-2004. Representative wave energy (RWE) was modeled for each interval using local bathymetry and wind data. Average SCR across all shoreline types for the entire time period ranged from -2.3 to +1.0 m y-1, with a mean SCR of -0.3 m y-1. This translates to an average loss of ∼13 m for any given point over the 48-year period covered by this study. The most negative average SCR (greatest erosion) occurred along unvegetated sediment bank shorelines (-0.39 m y-1). Change along marsh shorelines (-0.18 m y-1) was lower than along sediment banks, and narrow fringing marsh associated with sediment bank shorelines significantly reduced bank erosion. Modeled RWE values were positively correlated with erosion only in the highest wave-energy settings. Erosion of sediment bank shorelines provides a conservative estimate of 17,660 m3 of sediment each year to the estuary, with marsh erosion contributing up to an additional 1900 m3 y-1. Based on analysis of the sediment volume required to maintain marsh surface elevation with respect to sea level, we hypothesize that shoreline erosion plays a vital role in supporting growth and maintenance of downstream marshes. © Coastal Education & Research Foundation 2015. Source


Ross S.W.,University of North Carolina at Wilmington | Rhode M.,University of North Carolina at Wilmington | Viada S.T.,CSA Ocean science Inc. | Mather R.,University of Rhode Island
Fishery Bulletin | Year: 2016

Fish species of the Middle Atlantic Bight (MAB) continental shelf are well known; however, species occupying hard-bottom habitats, particularly on the outer shelf, are poorly documented. Reef-like habitats are relatively uncommon on the MAB shelf; therefore, shipwrecks may represent a significant habitat resource. During fall 2012 and spring 2013, 9 sites (depths: 42–126 m) near Norfolk Canyon were surveyed by using remotely operated vehicles. One site consisted of sand bottom, one consisted of predominantly natural hard bottom, and 7 sites included 8 large shipwrecks. Of 38 fish taxa identified, 33 occurred on hard bottom and 25 occurred on soft substrata. Fourteen fish taxa occurred almost exclusively on hard bottom, and 6 species were observed only on soft bottom. The most abundant taxa, especially on reef habitat, were the chain dogfish (Scyliorhinus retifer), a scorpionfish (Scorpaena sp.), the yellowfin bass (Anthias nicholsi), the red barbier (Baldwinella vivanus), the black sea bass (Centropristis striata), unidentified anthiine serranids, and the deepbody boarfish (Antigonia capros). Depth, location, and season did not significantly influence fish assemblages. Fish assemblages on natural and artificial hard-bottom habitat were similar but significantly different from soft-bottom assemblages. Deep-reef fishes of the southern MAB may be constrained by zoogeography, depth, and inadequate habitat— limitations that could increase their vulnerability. © National Marine Fisheries Service 2016. All rights reserved. Source


Cunha A.H.,University of Algarve | Erzini K.,University of Algarve | Serrao E.A.,University of Algarve | Goncalves E.,Eco ethology Research Unit | And 8 more authors.
Journal of Coastal Conservation | Year: 2014

The Marine Park Prof. Luiz Saldanha, in the coast of Arrábida, is the first marine park in continental Portugal. This area is a Nature 2000 site and is considered to be a hotspot for European marine biodiversity. In 2005, the management plan of the park was implemented, ending several habitat menaces, thereby allowing an application to the LIFE—NATURE Programme. The LIFE-BIOMARES project aimed at the restoration and management of the biodiversity of the marine park through several actions. The restoration of the seagrass prairies that were completely destroyed by fishing activities and recreational boating, was one of the most challenging. It included the transplanting of seagrasses from donor populations and the germination of seagrass seeds for posterior plantation to maintain genetic diversity in the transplanted area. One of the most popular actions was the implementation of environmental friendly moorings to integrate recreational use of the area with environmental protection. Several dissemination and environmental education actions concerning the marine park and the project took place and contributed to the public increase of the park acceptance. The seabed habitats were mapped along the park and a surrounding area to 100 m depth in order to create a habitat cartography of the park and to help locate alternative fishing zones. Biodiversity assessments for macrofauna revealed seasonal variations and an effect of the protection status. Preliminary results are presented and show that the marine park regulations are having a positive effect on biodiversity conservation and sustainable fisheries, thereby showing that these kind of conservation projects are important to disseminate coastal conservation best practices. The Biomares project is a model project that can be followed in the implementation of marine reserves and the establishment of the Natura 2000 marine network. © 2014, Springer Science+Business Media Dordrecht. Source

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