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A recent biological characterization of the Davidson Seamount off central California using a remotely operated vehicle revealed communities rich with deep-sea corals. During this characterization several corals were collected and three colonies were made available for an age and growth study. The colonies examined were identified as bubblegum coral ( Paragorgia sp.), bamboo coral ( Keratoisis sp.), and precious coral ( Corallium sp.). Age was estimated from growth zone counts made in skeletal cross sections. These age estimates were used to estimate growth rates and colony age. Estimated growth rates determined for each species were quite different. The bubblegum coral had a relatively high estimated growth rate, with the precious and bamboo coral estimated as slow growing. These age and growth observations were evaluated relative to published studies on related species and an attempt was made to validate the age and growth estimates with an independent radiometric ageing technique (i.e., lead-210 dating). This approach was not successful for the bubblegum coral, and was successful for the bamboo and precious corals to differing degrees. For the bamboo coral, a minimum colony age of over 200 years was determined. For the precious coral, a linear growth rate of approximately 0.25 cm/yr led to a colony age of about 115 years; however, based on the radial growth rate, an age of up to 200 year is possible.

Two samples of the calcitic deep-sea coral Primnoa resedaeformis have been analysed for Mg/Ca ratios by micro-beam methods ( laser-ablation ICP-MS and electron microprobe). Continuous profiles of Mg/Ca have been studied with the aim of establishing the reproducibility of the variations in different parts of the coral, and therefore the potential use of Mg/Ca as a paleoceanographic or paleoclimatic tracer. A method of spectral decomposition based on box-filter smoothing has been developed for analysing the signals. This method shows that all profiles measured contain some degree of irreproducibility. Much of this irreproducibility appears to be white-noise added by the analytical methods. The amplitude of this noise is around 15 % of the signal average for the Nd-YAG laser-ablation system at Memorial University of Newfoundland, 5–6 % for the electron microprobe at Dalhousie University, and 4–4.5 % for the ArF Excimer laser-ablation system at the Australian National University. In the case of the LA-ICP-MS analyses, this noise may relate to uneven ablation of material from the coral and/or an uneven size distribution of particles entering the ICP-MS plasma. For the most stable system (ANU’s LA-ICP-MS), features on distance scales smaller than 150–200 µm will be obscured by the noise, and features smaller than 500 µm should be interpreted with caution. There is some evidence that the coral itself contains compositional heterogeneity, although reproducibility is mostly limited by instrumental noise. We recommend that several analytical profiles be compared before any attempt is made to interpret Mg/Ca variations in terms of paleoceanographic changes.

It has been suggested that the deep-sea gorgonian coral Primnoa resedaeformis may be an important paleoceanographic archive. Seventeen colonies collected from the upper slope of the NW Atlantic margin (229 – 447 m) were analyzed to see if skeletal Mg/Ca is related to temperature. Analyses were focused on the calcite cortex region of skeletal sections to avoid interference from organic Mg in the horny layers found closer to the center of sections. Comparison of bulk skeletal Mg/Ca with hydrographic temperature yielded the relationship Mg/Ca (mmol/mol)=5 (+/− 1.4) T (°C)+64 (+/− 10). This relationship was used to calibrate profiles of Mg/Ca measured across the annual rings of one large, well-dated colony, over the period 1950–2002. Mg/Ca profiles were broadly consistent among three sections spaced 10 cm apart along the main trunk of the colony. These profiles were in general agreement with the local instrumental record of temperature at 375 – 450 m. Some discrepancies between the coral and instrumental records of temperature may be a result of chronological error, poor sampling density, or additional factors influencing Mg partitioning in the coral. Overall, these preliminary results support the hypothesis that temperature drives Mg/Ca in the skeletal calcite of this species. It appears that environmentally meaningful records from Primnoa resedaeformis will be found at decadal scales or longer.

Like other biogenic carbonate that can be dated, aragonite skeleton of deep-sea corals is a potential archive of oceanographic changes over time. Stable isotope analysis is commonly used in paleoceanographic reconstruction of past seawater temperatures, however, offset from isotopic equilibrium as well as recent observations about isotope distribution with the micro-structure of deep-water corals implies non direct paleoclimate reconstructions. Here we test the influence of the sampling scale on oceanographic interpretations. The stable isotope composition for different modern calyxes of Lophelia pertusa has been analyzed at different scales using either a macro or a micro-sampling technique. The comparison of the obtained results from the two sampling techniques shows that the isotopic variability observed with the micro-sampling is twice the one with macro-sampling. Moreover the macro-sampling is not an average of what happens at a more precise scale. Nevertheless a realistic seawater temperature estimate can be retrieved using the equation of Smith et al. (2000) for both the macro and the micro-sampled corals. However, a test of the reproducibility on a single calyx reveals important isotopic inhomogenities at a very fine scale (∼µm), yielding an external reproducibility of the seawater temperature estimates of about ±0.7°C for micro sampled corals.

The longest available time series on ocean currents indicates that the southward flow of water from the Greenland Sea is weakening, and that correlative large-amplitude changes have occurred in the rate of formation of intermediate Labrador Sea water. These have been linked to changes in regional climate which, if trends continue, could within 30 years alter the flow of the North Atlantic Drift and possibly interrupt the formation of Labrador Sea water, profoundly affecting regional climates, marine ecosystems and fisheries. We are attempting to use the carbonate skeletons of cold-water corals to find out how rapidly and how often the thermohaline circulation of the NE vs . NW Atlantic has changed in the past, just as tree rings and ice cores are used to investigate climate change on land. We have focussed on the NE Atlantic for our preliminary work, notably the Faroe-Shetland Channel: a major gateway between the Atlantic Ocean and the Norwegian Sea. Warm North Atlantic Drift water passes north through this channel on the surface, warming northern Europe. Cold Norwegian Sea Overflow Water returns at depth, contributing to the formation of North Atlantic Deep Water. Existing records are too short to allow conclusions regarding recent temporal changes in this inflow, so proxies are sought. We have analysed live-collected Lophelia pertusa skeletons collected in October 2001 using a ring dredge from RV Scotia along the worlds longest-running hydrographic transect (from 1893). Corals were sectioned using a slow-speed Isomet saw, and sampled for isotopic analysis using a Merchantek micromill. Observation of sectioned corals revealed dense-less dense couplets, as in every coral studied to date from tropical to deep cold-water environments worldwide. We sampled circumferentially, in the centres of individual bands, so as to produce temperature estimates using the “lines” technique of Smith et al. (2000). The results were simultaneously encouraging and confusing. Each of the coral samples generated lines from which temperatures could be estimated. Dense skeletal bands had lower temperatures than the less-dense bands, hence we conclude these were winter and summer bands, respectively. The mean annual temperature (MAT) range determined from one of the corals was 3.8°C. Pooling results from several corals yielded a lower estimate for MAT range: 2.3°C. The absolute temperatures from the corals, however, were somewhat lower than the instrumental record with “winter” records being more depleted than the “summer values”. This was unexpected and shows that determining detailed climate records from L. pertusa may be more difficult than hoped.

Zooxanthellate scleractinian corals have been shown to preserve important archives of seasonal variations of climate variables, such as sea surface temperature, salinity, and productivity. By analogy, the recognition of correlated chemical signals in azooxanthellate deep-water corals may provide an important new approach to help unravel the role of intermediate and deep waters in determining climate variability. A first step to determine the suitability of deep-water scleractinian corals as potential paleoceanographic-paleoclimatic tools requires the demonstration of coherent geochemical signals in their skeletons. With this in mind, trace and minor element ratios Sr/Ca, Mg/Ca, U/Ca, B/Ca, P/Ca, Ba/Ca and Mn/Ca have been measured in two deep-water solitary scleractinian corals ( Desmophyllum dianthus ) collected from Last Glacial submerged banks in the Mediterranean basin and in the Great Australian Bight. Most elements show distinct, highly correlated patterns of variation. Although preliminary, these results illustrate the potential use of trace and minor element concentrations in the deep-water scleractinian corals to provide new constraints on the composition and evolution of intermediate and deep waters and thus introduce new perspectives in paleoceanography, such as the assessment of changes in both deep-sea nutrient chemistry and ocean circulation.

The deep-sea (>200 m) represents the largest portion of the ocean, but it is probably the least understood because of the technological challenges and financial resources required to explore and research this environment. With the advancement of underwater technology, astonishing images of deep-sea corals living at depths from the surface to greater than 1000 m are now becoming available to both policy makers and the public. More specifically, in the North Atlantic Ocean, these images have led many countries to begin to assess the distribution, status, health, and potential threats faced by these important ecosystems, which appear to be connected by the uniting influence of the Gulf Stream and its associated currents. Since deep-sea coral ecosystems extend beyond national boundaries and encounter similar threats, it was determined that a cooperative effort on both sides of the Atlantic could be beneficial to maximize available resources, share expertise, and exchange data to rapidly increase scientific understanding of deep-sea coral ecosystems. Thus, an international Deep-Sea Corals Workshop was held to identify critical information needs related to: locating and mapping deep-sea corals; understanding more about coral biology and ecology; and using specific deep-sea coral species as indicators of climate change. Priority information needs identified at the workshop were the need to: (1) conduct both low- and high-resolution mapping to locate and characterize deep-sea coral habitats; (2) conduct research on factors that influence deep-sea coral life history patterns; (3) examine how they function as habitat for fish and invertebrate species; (4) develop a comprehensive inventory of deep-sea coral species; and (5) further efforts to analyze past climate changes and to improve climate forecasting models. Described herein are: the results of the Deep-Sea Corals Workshop ; other events with a focus on deep-sea corals; and potential pathways to increase U.S.-international collaborative partnerships.

As awareness of deep-sea corals increases, global efforts to conserve them are increasing as well. Oceana, a non-governmental conservation organization that merged with the American Oceans Campaign in 2002, is focusing significant attention and resources on the conservation of deep-sea coral communities in United States’ waters. Oceana is carrying out a number of activities as part of its deep-sea coral campaign. These include: • Working to pass legislation that would ban the use of particularly destructive bottom trawls in all U.S. waters in collaboration with the Marine Conservation Biology Institute; • Working to pass legislation that would specifically protect known deep-sea coral and sponge areas and establish a process for future protections; • Working to protect deep-sea coral and sponge habitats in the U.S. through the regional fishery management councils; • Developing educational materials for decision-makers, the media, and the general public; • Developing a petition to achieve threatened or endangered species status for Oculina varicosa . The goal of Oceana’s deep-sea coral protection activities is to ban bottom trawling in all U.S. waters containing significant amounts of deep-sea corals and sponges by the end of 2006. The purpose of this paper is to discuss the activities that Oceana is engaged in to achieve this goal. As Oceana’s capacity develops in other parts of the world, its efforts to protect coral in other regions (especially Europe and South America) will increase as well.

There is much debate about how to protect deep-sea coral and sponge ecosystems using the data currently available. The Aleutian Islands in Alaska contain some of the most abundant, diverse, and pristine deep-sea coral and sponge ecosystems on Earth. From 1990 to 2002, U.S. federal fishery observer data indicates approximately 2,176,648 kg of coral and sponge bycatch occurred in the Aleutian Islands, equaling 52 % of all coral and sponge bycatch in Alaska. Coral and sponge bycatch rates in the Aleutians were over 12 times the rate in the Bering Sea or Gulf of Alaska. The National Marine Fisheries Service (NMFS) estimates that 87 % of coral bycatch and 91 % of sponge bycatch is caused by bottom trawling in the Bering Sea/Aleutian Islands management areas. The conservation organization Oceana developed an interdisciplinary fishery management approach to mitigating adverse impacts of fishing on deep-sea coral and sponge ecosystems, which has been used by NMFS to formulate a habitat protection alternative for the Aleutian Islands that is being considered in an Environmental Impact Statement. The Oceana Approach is offered as a cost effective model for reducing the adverse effects of fishing on deep-sea coral and sponge ecosystems. The approach uses observer data to identify areas of high coral and sponge bycatch rates to develop a comprehensive management policy that allows bottom trawling only in specific designated areas with high fish harvest and low habitat impacts. All areas not specified as open would be closed to bottom trawling. To prevent effort displacement, bottom trawl effort is reduced by the amount that historically occurred in areas that would become closed. The Oceana Approach also includes coral and sponge bycatch limits and a plan for comprehensive seafloor research, mapping, and monitoring. An enforcement strategy for these management measures is developed based on agency capabilities, and includes increased observer coverage, vessel monitoring systems, and electronic logbooks. This approach allows for continued catch of target species with minimal adverse impacts on coral and sponge habitat. Successful implementation of the Oceana Approach will protect areas of high known trawl impacts to deep-sea coral and sponge ecosystems and prevent trawl effort from moving into new, unexplored areas. The methodology is recommended for application to other regions and should be adjusted based on the available fishery and biological data for each region.

The conservation of deep-sea corals is of growing interest in the United States. A range of issues including biodiversity protection, conservation of seafloor habitats, and the role of deep-sea corals as essential fish habitat places greater significance on understanding the distributions of these corals and fishing activities. At the same time overfishing of some groundfish populations highlights the need for ecosystem-based management. Here we present records of habitat-forming deep-sea corals from the United States Pacific Fishery Management Council region that we analyze in relation to differential ecological impacts of demersal fishing gears. We use an ecological footprint approach combining groundfish catch by gear type with a previously published ecological severity ranking of fishing gears. Deep-sea corals in the Isididae, Paragorgiidae, Primnoidae, Antipathidae and Stylasteriidae families are widespread throughout their depth ranges in the Northeast Pacific, although the scleractinian families Oculinidae and Caryophylliidae are relatively rare. In this qualitative analysis, we highlight areas of relatively high coral concentration such as the West Coast continental shelf break and Monterey submarine canyon, areas that are presently relatively lightly fished but where corals are recorded. Bottom trawling gear has far and away the region’s largest ecological footprint. Other gears with smaller footprints include bottom longline, pot/trap and hook and line gear. Most of these impacts seem to have occurred in areas where deep-sea corals are relatively scarce, but fishing closures to protect rockfish implemented in 2002 may have the unfortunate effect of redistributing fishing effort to areas of deep-sea coral aggregations. An ecosystem-based management approach would detect and prevent such unintended consequences of redistributing fishing effort and placing deep-sea corals in harm’s way.