The framework-forming coral Lophelia pertusa

Andrew J. Davies and John Guinotte

Cold-water corals are found in all the oceans of the world. Usually below 200 metres, they create structurally complex habitat that gives rise to a unique deep-sea ecosystem in, what otherwise may be a relatively featureless area. Numerous other filter-feeding organisms are found, along with fish that may use the coral as a nursery ground. Yet, we don’t know where many occurrences of cold-water coral are….

This is where habitat suitability modelling comes in. By using the best available scientific information and powerful statistical tools, we are able to predict, based on the species environmental requirements where they are likely to occur. Mine and John’s work, published in PLoS ONE is an important step towards turning habitat suitability modelling into a viable tool for the protection of vulnerable marine ecosystems in the deep sea. This paper represents several years of work, designing and constructing new approaches to allow us to model coral distributions at high resolution. The outputs speak for themselves, with a 1 km resolution, we may finally be able to say to other researchers, go here, you have a good chance of finding coral in this area. Or, we may be able to say, there is a high probability of coral occurrence here, perhaps we could designate this area closed to bottom contact fishing or other exploitation.

Read the abstract below, or download the PDF from either my site or the PLoS ONE site.

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Full citation

Davies AJ, Guinotte JM (2011) Global Habitat Suitability for Framework-Forming Cold-Water Corals. PLoS ONE 6(4): e18483. doi:10.1371/journal.pone.0018483

Abstract

Predictive habitat models are increasingly being used by conservationists, researchers and governmental bodies to identify vulnerable ecosystems and species’ distributions in areas that have not been sampled. However, in the deep sea, several limitations have restricted the widespread utilisation of this approach. These range from issues with the accuracy of species presences, the lack of reliable absence data and the limited spatial resolution of environmental factors known or thought to control deep-sea species’ distributions. To address these problems, global habitat suitability models have been generated for five species of framework-forming scleractinian corals by taking the best available data and using a novel approach to generate high resolution maps of seafloor conditions. High-resolution global bathymetry was used to resample gridded data from sources such as World Ocean Atlas to produce continuous 30-arc second (~1 km²) global grids for environmental, chemical and physical data of the world’s oceans. The increased area and resolution of the environmental variables resulted in a greater number of coral presence records being incorporated into habitat models and higher accuracy of model predictions. The most important factors in determining cold-water coral habitat suitability were depth, temperature, aragonite saturation state and salinity. Model outputs indicated the majority of suitable coral habitat is likely to occur on the continental shelves and slopes of the Atlantic, South Pacific and Indian Oceans. The North Pacific has very little suitable scleractinian coral habitat. Numerous small scale features (i.e., seamounts), which have not been sampled or identified as having a high probability of supporting cold-water coral habitat were identified in all ocean basins. Field validation of newly identified areas is needed to determine the accuracy of model results, assess the utility of modelling efforts to identify vulnerable marine ecosystems for inclusion in future marine protected areas and reduce coral bycatch by commercial fisheries.

Published in Marine Ecology Process Series 397.

The Mingulay reef complex in the Sea of the Hebrides west of Scotland was first mapped in 2003 with a further survey in 2006 revealing previously unknown live coral reef areas at 120 to 190 m depth. Habitat mapping confirmed that distinctive mounded bathymetry was formed by reefs of Lophelia pertusa with surficial coral debris dating to almost 4000 yr. Benthic lander and mooring deployments revealed 2 dominant food supply mechanisms to the reefs: a regular rapid downwelling of surface water delivering pulses of warm fluorescent water, and periodic advection of high turbidity bottom waters. Closed chamber respirometry studies suggest that L. pertusa responds to seawater warming, such as that seen during the rapid downwelling events, with increases in metabolic rate. Lipid biomarker analysis implies that corals at Mingulay feed predominantly on herbivorous calanoid copepods. Integrating geophysical and hydrographical survey data allowed us to quantify the roles of these environmental factors in controlling biodiversity of attached epifaunal species across the reefs. Longitudinal structuring of these communities is striking: species richness (α) and turnover (β) change significantly west to east, with variation in community composition largely explained by bathymetric variables that are spatially structured on the reef complex. Vibro-cores through the reef mounds show abundant coral debris with significant hiatuses. High resolution side-scan sonar revealed trawl marks in areas south of the coral reefs where vessel monitoring system data showed the highest density of local fishing activity. The interdisciplinary approach in this study allowed us to record the food supply and hydrographic environment experienced by L. pertusa and determine how it may be ecophysiologically adapted to these conditions. Improved basic understanding of cold-water coral biology and biodiversity alongside efforts to map and date these long-lived habitats are vital to development of future conservation policies.

Full citation

Roberts, J.M., Davies, A.J., Henry, L.-A., Dodds, L.A., Duineveld, G.C.A., Lavaleye, M.S.S., Maier, C., van Soest, R.W.M., Bergman, M.J.N., Hühnerbach, V., Huvenne, V.A.I., Sinclair, D.J., Watmough, T., Long, D., Green, S.L. & van Haren, H. (2009) “Mingulay reef complex, northeast Atlantic: an interdisciplinary study of cold-water coral habitat, hydrography and biodiversity.” Marine Ecology Progress Series 397: 139-151.

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The Lophelia pertusa community at Viosca Knoll (VK826) is the most extensive found to date in the Gulf of Mexico. As part of a multi-disciplinary study, the physical setting of this area was described using benthic landers, CTD transects and remotely operated vehicle observations. The site was broadly characterised into three main habitats: (1) dense coral cover that resembles biogenic reef complexes, (2) areas of sediment, and (3) authigenic carbonate blocks with sparse coral and chemosynthetic communities. The coral communities were dominated by L. pertusa but also contained numerous solitary coral species. Over areas that contained L. pertusa, the environmental conditions recorded were similar to those associated with communities in the north-eastern Atlantic, with temperature (8.5–10.6 °C) and salinity (ca. 35) falling within the known species niche for L. pertusa. However, dissolved oxygen concentrations (2.7–2.8 ml l⁻¹) and density (σ_Θ, 27.1–27.2 kg m⁻³) were lower and mass fluxes from sediment trap data appeared much higher (4002–4192 mg m⁻² d⁻¹). Yet, this species still appears to thrive in this region, suggesting that L. pertusa may not be as limited by lower dissolved oxygen concentrations as previously thought. The VK826 site experienced sustained eastward water flow of 10–30 cm s⁻¹ over the 5-day measurement period but was also subjected to significant short-term variability in current velocity and direction. In addition, two processes were observed that caused variability in salinity and temperature; the first was consistent with internal waves that caused temperature variations of 0.8 °C over 5–11 h periods. The second was high-frequency variability (20–30 min periods) in temperature recorded only at the ALBEX site. A further pattern observed over the coral habitat was the presence of a 24 h diel vertical migration of zooplankton that may form part of a food chain that eventually reaches the corals. The majority of detailed studies concerning local environmental conditions in L. pertusa habitats have been conducted within the north-eastern Atlantic, limiting most knowledge of the niche of this species to a single part of an ocean basin. Data presented here show that the corals at VK826 are subjected to similar conditions in temperature, salinity, and flow velocity as their counterparts in the north-east Atlantic, although values for dissolved oxygen and density (sigma-theta: σ_Θ) are different. Our data also highlight novel observations of short-term environmental variability in cold-water coral habitat.

Published in Deep Sea Research vol one 57.

Full Citation

Davies, A.J., Duineveld, G.C.A., van Weering, T.C.E., Mienis, F., Quattrini, A.M., Seim, H.E., Bane, J.M. & Ross, S.W. (2010) “Short-term environmental variability in cold-water coral habitat at Viosca Knoll, Gulf of Mexico.” Deep-sea Research Vol 1. 57(2): 199-212.

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The conference was headed: “Issues confronting the deep oceans: the economic, scientific and governance challenges and oppotuinites of working in the deep sea”. I was invited to present in a special session chaired by Jeff Ardron and Liz McLanahan entitled “Linking deep sea science to international decisions: Vulnerable and ecologically significant areas”.

My presentation was “Predicting the distribution of framework forming corals” and included updates on my new modelling processes and more importantly a new suite of environmental variables at a 30 arc second resolution (1 km). The presentation is available for viewing by clicking below. If you have any questions, or are interested in collaborating don’t hesitate to contact me.

Download the presentation here: Davies et al 2009 ICES presentation (458)

In 2006 and 2007, multiple deployments of current meters and optical sensors on landers and moorings were made in the first detailed in situ study of the particle supply to the coral community in the Mingulay Reef complex in the Sea of Hebrides at 140 m water depth. Two distinct and predictable supply mechanisms were resolved. One mechanism consisted of the rapid downwelling of surface water caused by hydraulic control of tidal flow that transports particles from the surface to the corals in less than an hour. The rapid downwelling was recorded on the reef top as a pulse of warm, fluorescent, and relatively clear water at the onset of the flood and ebb tides. The pulse was strongest after flood tide and lasted for up to 3 hours. The second mechanism consisted of advection onto the reef of deep bottom water with a high suspended matter load. This advection occurred during peak tides and was combined with topographical current acceleration on the reef top enhancing delivery of particles to the corals.

Published as feature article in Limnology and Oceanography

http://www.aslo.org/lo/pdf/vol_54/issue_2/0620.pdf

Full citation

Davies, A.J., Duineveld, G.C.A., Lavaleye, M.S.S., Bergman, M.J.N., van Haren, H. & Roberts, J.M. (2009) “Downwelling and deep-water bottom currents as food supply mechanisms to the cold-water coral Lophelia pertusa (Scleractinia) at the Mingulay Reef Complex.” Limnology and Oceanography 54(2): 620-629.

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An important aim of large, pan-European scientific projects with numerous research groups is to integrate and visualize the acquired distributed data sets and results. The large volume of diverse data gathered and the need to disseminate results among the scientific community and beyond requires using a Geographic Information System (GIS). This article presents our experiences in creating a unified Web-based GIS for HERMES. The HERMES-GIS is based on Web Mapping Services that include direct links to the World Data Center for Marine Environmental Science and its large, long-term geoscience data archive and publication unit, PANGAEA (http://www.pangaea.de). It incorporates metadata and data from all project partners to provide users with basic analytical and visualization tools for archived (distributed) and personal (local) data, and it is also a policymaking tool. Additionally, we illustrate two important GIS applications inside the HERMES community— the use of data models to integrate several subdisciplines and the use of predictive habitat modeling.

Publication in Oceanography 22(1).

Full citation

De Mol B, Querol N, Davies AJ, Schäfer A, Foglini F, Gonzales-Mirelis G, Kopke K, Dunne D, Shewe I, Trincardi F, Canals M (2009) HERMES-GIS: a tool to connect scientists. Oceanography 22(1): 144-153.

http://www.tos.org/oceanography/

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I’m currently visiting the University of North Carolina at Wilmington. I’ve only been to America once before, for a conference in Miami in 2005. I found the adjustment for that quite difficult. Yet, at Wilmington, it has a continental feel that has made my adjustment quite easy.

At UNCW, I’ve visiting the lab of Dr Steve Ross, a researcher on cold-water corals. Steve is primarily a fish biologist who has an expansive expertise in deep-sea biology. His lab is based in the woods adjacent to the Marine Center of UNCW. The small lab is far different to other places I’ve worked, yet the team feel of the group is second to none.

We’re due to fly down to Mississippii to meet the RV Nancy Foster on the 1st October. It should be good.

21st September 2008 – 3rd November 2008

I am just starting my Winston Churchill Memorial Trust Travelling Fellowship (WCMT) to the USA. My project for 2008 is entitled “Preserving the UK’s deep-sea heritage“. Within the confines of the fellowship, I’m travelling the US, meeting scientists and hopefully forging future collaborations. A highlight of the fellowship is a 2 week research cruise in the Gulf of Mexico. I’ll be joining a team of US researchers on the R/V Nancy Foster, we’ve access to an ROV and we’ll be deploying landers with some of my equipment on it for almost a year. These opportunities do not come often!

So far, I’ve made it to the University of North Carolina Wilmington. The trip from the UK took a combined total of over 20 hours. By hour 24, I’d firmly planted my head on the bed of the motel where I’m staying for the next 9 days until I fly to Pascagoula to meet the ship. I’ll be there for 4 days prepping the lander equipment before we set sail on the 5th October. We return on the 16th, and after a few days I fly to Seattle to the Marine Conservation Biology Institute. That rounds up the trip!

Today, 24th September, I’m in Wilmington NC. I’ve been meeting up with Dr Steve Ross. Steve is the chief scientist of the cruise and we’re just formulating ideas and discussing the science that we’ll do in the Gulf of Mexico.

Published in Deep-sea Research Vol. 1 (2008)

Ecological-niche factor analysis (ENFA) was applied to the reef framework-forming cold-water coral Lophelia pertusa. The environmental tolerances of this species were assessed using readily available oceanographic data, including physical, chemical, and biological variables. Lophelia pertusa was found at mean depths of 468 and 480 metres on the regional and global scales and occupied a niche that included higher than average current speed and productivity, supporting the theory that their limited food supply is locally enhanced by currents. Most records occurred in areas with a salinity of 35, mean temperatures of 6.2-6.7 °C and dissolved oxygen levels of 6.0-6.2 ml l-1. The majority of records were found in areas that were saturated with aragonite but had low concentration of nutrients (silicate, phosphate, and nitrate). Suitable habitat for L. pertusa was predicted using ENFA on a global and a regional scale that incorporated the north-east Atlantic Ocean. Regional prediction was reliable due to numerous presence points throughout the area, whereas global prediction was less reliable due to the paucity of presence data outside of the north-east Atlantic. However, the species niche was supported at each spatial scale. Predicted maps at the global scale reinforced the general consensus that the North Atlantic Ocean is a key region in the worldwide distribution of L. pertusa. Predictive modelling is an approach that can be applied to cold-water coral species to locate areas of suitable habitat for further study. It may also prove a useful tool to assist spatial planning of offshore marine protected areas. However, issues with eco-geographical datasets, including their coarse resolution and limited geographical coverage, currently restrict the scope of this approach.

Full citation

Davies, A.J., Wisshak, M., Orr, J.C. & Roberts, J.M. (2008) “Predicting suitable habitat for Lophelia pertusa” Deep-sea Research Volume 1, 55: 1048-1062. j.dsr.2008.04.010

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Human activity in the deep sea is extending ever deeper, with recent research showing that this environment is more sensitive to human and natural impacts than previously thought. Some deep-water fish stocks have collapsed and fishing methods such as bottom trawling have raised international concern over the habitat damage they cause. It is likely that in its current form, deep-sea fishing is unsustainable. Diminishing reserves of hydrocarbons in shallow water are pushing exploration and production into deeper waters, which may cause damage to little known deep-sea habitats. The deep sea is also proposed as an environment where anthropogenic carbon dioxide could be stored to minimise the effect of its release into the atmosphere. At the same time, rising atmospheric carbon dioxide levels may be altering the chemical equilibrium of the global ocean by lowering pH. Many countries are now beginning to designate some deep-sea habitats as marine protected areas in measures to reduce the damage caused by fishing and other anthropogenic activities. This review examines these current and emerging issues in deep-sea conservation and discusses conservation status and the designation of protected areas. The enforcement of protected areas using satellite tracking of vessels is discussed and applied to an internationally agreed deep-water conservation area, which aims to protect cold-water coral habitats on the Darwin Mounds in the north east Atlantic Ocean.

Full citation

Davies, A.J., Roberts, J.M. & Hall-Spencer, J. (2007) “Preserving deep-sea natural heritage: Emerging issues in offshore conservation and management” Biological Conservation 138: 299-312.

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