Sandra Brooke

Environmental Impacts of the Deep-Water Oil and Gas Industry: A Review to Guide Management Strategies

The industrialization of the deep sea is expanding worldwide. Expanding oil and gas exploration activities in the absence of sufficient baseline data in these ecosystems has made environmental management challenging. Here, we review the types of activities that are associated with global offshore oil and gas development in water depths over 200 m, the typical impacts of these activities, some of the more extreme impacts of accidental oil and gas releases, and the current state of management in the major regions of offshore industrial activity including 18 exclusive economic zones. Direct impacts of infrastructure installation, including sediment resuspension and burial by seafloor anchors and pipelines, are typically restricted to a radius of approximately 100 m on from the installation on the seafloor. Discharges of water-based and low-toxicity oil-based drilling muds and produced water can extend over 2 km, while the ecological impacts at the population and community levels on the seafloor are most commonly on the order of 200-300 m from their source. These impacts may persist in the deep sea for many years and likely longer for its more fragile ecosystems, such as cold-water corals. This synthesis of information provides the basis for a series of recommendations for the management of offshore oil and gas development. An effective management strategy, aimed at minimizing risk of significant environmental harm, will typically encompass regulations of the activity itself (e.g. discharge practices, materials used), combined with spatial (e.g. avoidance rules and marine protected areas) and temporal measures (e.g. restricted activities during peak reproductive periods). Spatial management measures that encompass representatives of all of the regional deep-sea community types is important in this context. Implementation of these management strategies should consider minimum buffer zones to displace industrial activity beyond the range of typical impacts: at least 2 km from any discharge points and surface infrastructure and 200 m from seafloor infrastructure with no expected discharges. Although managing natural resources is, arguably, more challenging in deep-water environments, inclusion of these proven conservation tools contributes to robust environmental management strategies for oil and gas extraction in the deep sea.

Embryogenesis and larval biology of the cold-water coral Lophelia pertusa.

Cold-water coral reefs form spectacular and highly diverse ecosystems in the deep sea but little is known about reproduction, and virtually nothing about the larval biology in these corals. This study is based on data from two locations of the North East Atlantic and documents the first observations of embryogenesis and larval development in Lophelia pertusa, the most common framework-building cold-water scleractinian. Embryos developed in a more or less organized radial cleavage pattern from ∼160 µm large neutral or negatively buoyant eggs, to 120–270 µm long ciliated planulae. Embryogenesis was slow with cleavage occurring at intervals of 6–8 hours up to the 64-cell stage. Genetically characterized larvae were sexually derived, with maternal and paternal alleles present. Larvae were active swimmers (0.5 mm s−1) initially residing in the upper part of the water column, with bottom probing behavior starting 3–5 weeks after fertilization. Nematocysts had developed by day 30, coinciding with peak bottom-probing behavior, and possibly an indication that larvae are fully competent to settle at this time. Planulae survived for eight weeks under laboratory conditions, and preliminary results indicate that these planulae are planktotrophic. The late onset of competency and larval longevity suggests a high dispersal potential. Understanding larval biology and behavior is of paramount importance for biophysical modeling of larval dispersal, which forms the basis for predictions of connectivity among populations.

Occurrence of deep-water Lophelia pertusa and Madrepora oculata in the Gulf of Mexico

One of the critical information needs identified at the 2003 Deep-Sea Corals Workshop in Galway, Ireland, was to locate and chart deep-sea corals in order to develop reliable estimates of their distribution and abundance. While reports of deep-sea corals from the Gulf of Mexico date back to the 1860s, relatively little is known about their distribution or abundance. This paper attempts to provide a current assessment of the occurrence of Lophelia pertusa and Madrepora oculata in water depths greater than 200 m in the Gulf of Mexico by summarizing records from (1) published material, (2) the 2003 National Museum of Natural History Taxonomic Database, (3) findings obtained during the September-October 2003 NOAA-OE RV Ronald H. Brown cruise RB-03-07-leg-2 in the northern Gulf, and (4) from various unpublished sources.

Coral-associated bacterial diversity is conserved across two deep-sea Anthothela species

Cold-water corals, similar to tropical corals, contain diverse and complex microbial assemblages. These bacteria provide essential biological functions within coral holobionts, facilitating increased nutrient utilization and production of antimicrobial compounds. To date, few cold-water octocoral species have been analyzed to explore the diversity and abundance of their microbial associates. For this study, 23 samples of the family Anthothelidae were collected from Norfolk (n = 12) and Baltimore Canyons (n = 11) from the western Atlantic in August 2012 and May 2013. Genetic testing found that these samples comprised two Anthothela species (Anthothela grandiflora and Anthothela sp.) and Alcyonium grandiflorum. DNA was extracted and sequenced with primers targeting the V4–V5 variable region of the 16S rRNA gene using 454 pyrosequencing with GS FLX Titanium chemistry. Results demonstrated that the coral host was the primary driver of bacterial community composition. Al. grandiflorum, dominated by Alteromonadales and Pirellulales had much higher species richness, and a distinct bacterial community compared to Anthothela samples. Anthothela species (A. grandiflora and Anthothela sp.) had very similar bacterial communities, dominated by Oceanospirillales and Spirochaetes. Additional analysis of core-conserved bacteria at 90% sample coverage revealed genus level conservation across Anthothela samples. This core included unclassified Oceanospirillales, Kiloniellales, Campylobacterales, and genus Spirochaeta. Members of this core were previously recognized for their functional capabilities in nitrogen cycling and suggest the possibility of a nearly complete nitrogen cycle within Anthothela species. Overall, many of the bacterial associates identified in this study have the potential to contribute to the acquisition and cycling of nutrients within the coral holobiont.

Bacterial Community Diversity Of The Deep-sea Octocoral Paramuricea Placomus

Compared to tropical corals, much less is known about deep-sea coral biology and ecology. Although the microbial communities of some deep-sea corals have been described, this is the first study to characterize the bacterial community associated with the deep-sea octocoral, Paramuricea placomus. Samples from five colonies of P. placomus were collected from Baltimore Canyon (379–382 m depth) in the Atlantic Ocean off the east coast of the United States of America. DNA was extracted from the coral samples and 16S rRNA gene amplicons were pyrosequenced using V4-V5 primers. Three samples sequenced deeply (>4,000 sequences each) and were further analyzed. The dominant microbial phylum was Proteobacteria, but other major phyla included Firmicutes and Planctomycetes. A conserved community of bacterial taxa held in common across the three P. placomus colonies was identified, comprising 68–90% of the total bacterial community depending on the coral individual. The bacterial community of P. placomus does not appear to include the genus Endozoicomonas, which has been found previously to be the dominant bacterial associate in several temperate and tropical gorgonians. Inferred functionality suggests the possibility of nitrogen cycling by the core bacterial community.

Habitat Characterization, Distribution, and Areal Extent of Deep-sea Coral Ecosystems off Florida, Southeastern U.S.A.

Abstract. The deep-sea (200–1000 m) seafloor off the southeastern U.S. has a variety of extensive deep-sea coral ecosystem (DSCE) habitats including: deep-water coral mounds; various hard-bottom habitats off Florida including the Miami Terrace, Pourtalès Terrace, and deep-water canyons (Agassiz and Tortugas Valleys); and deep island slopes off western Bahamas and northern Cuba. The dominant structure-forming scleractinian corals are Lophelia pertusa and Enallopsammia profunda; other structure-forming taxa include stylasterid corals, gorgonians, black corals, and sponges. This biota is associated with hard-bottom seafloor of variable high-relief topography which can be remotely identified from bathymetric data. NOAA bathymetric contour maps and digital elevation models were used to identify and delineate the areal extent of potential DSCE habitat in the region from northeastern Florida through the Straits of Florida. These were ground-truthed with 241 dives with submersibles and remotely operated vehicles which confirmed deep-sea coral habitat. We estimate a total of 39,910 km2 of DSCE habitat in this region. By comparison, the estimated areal extent of shallow-water coral habitat for all U.S. waters is 36,813 km2. Bottom trawling remains the greatest threat to DSCEs worldwide, and as a result NOAA has established five deep-water Coral Habitat Areas of Particular Concern (CHAPCs), encompassing 62,714 km2 from North Carolina to south Florida, which will protect much of the known deep-sea coral habitat in this region. High-resolution surveys are not only critical to define DSCE habitats but also to define areas devoid of coral and sponge habitats that may allow for potential bottom fisheries and energy development.

Comparison of microbiomes of cold-water corals Primnoa pacifica and Primnoa resedaeformis , with possible link between microbiome composition and host genotype

Cold-water corals provide critical habitats for a multitude of marine species, but are understudied relative to tropical corals. Primnoa pacifica is a cold-water coral prevalent throughout Alaskan waters, while another species in the genus, Primnoa resedaeformis, is widely distributed in the Atlantic Ocean. This study examined the V4-V5 region of the 16S rRNA gene after amplifying and pyrosequencing bacterial DNA from samples of these species. Key differences between the two species’ microbiomes included a robust presence of bacteria belonging to the Chlamydiales order in most of the P. pacifica samples, whereas no more than 2% of any microbial community from P. resedaeformis comprised these bacteria. Microbiomes of P. resedaeformis exhibited higher diversity than those of P. pacifica, and the two species largely clustered separately in a principal coordinate analysis. Comparison of P. resedaeformis microbiomes from samples collected in two submarine canyons revealed a significant difference between locations. This finding mirrored significant genetic differences among the P. resedaeformis from the two canyons based upon population genetic analysis of microsatellite loci. This study presents the first report of microbiomes associated with these two coral species.