Sabellaria spinulosa

Many aquatic organisms rely on the suspension of particulate matter for food or for building materials, yet these conditions are difficult to replicate in laboratory mesocosms. Consequently, husbandry and experimental conditions may often be sub-optimal. The VOrtex Resuspension Tank (VORT) is a simple and reliable system for the resuspension of food or sediments using an enclosed airlift. The particle rain from the lift is mixed in the tank by two water inputs that provide directional current flow across the study organism(s). The vortex mixing creates a turbulent lateral water flow that allows the distribution of particulate matter outwards from the sediment outflow. By calibrating a VORT it is possible to control sedimentation rate by manipulating water and air flow rates. As an example application, three VORTs were maintained under different sediment loading to assess the sediment fraction utilisation and tube growth rates of the tube-building polychaete worm Sabellaria spinulosa. S. spinulosa consistently utilised a lower mean particle size than that of the background sediment when provided with well sorted medium sands. Under sediment starved conditions, there was net erosion of colonies whereas under intermediate and high sediment rates there was consistent cumulative growth throughout a 15 d experiment. This highlights the importance of suspended sediment for S. spinulosa and also the suitability of the VORT system for maintaining organisms with suspended matter requirements.

Publication in press with Journal of Experimental Marine Biology and Ecology

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Davies, A.J., Last, K.S., Attard, K. & Hendrick, V.J. (accepted) “Maintaining turbidity and current flow in laboratory aquarium studies, a case study using Sabellaria spinulosa” Journal of Experimental Marine Biology and Ecology.

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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.

Publication in press with Limnology and Oceanography

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Davies, A.J., Duineveld, G.C.A., Lavaleye, M.S.S., Bergman, M.I.N., van Haren, H. & Roberts, J.M. (accepted) “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.

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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.

One particularly notable attempt was to quantify and identify the fish community in the area, the water depth is nearly 1000 m. We used a timed bait release system mounted on the ALBEX lander and attached a new SAMS infra-red camera.

The results were pretty good. You can see a sneak preview below:

Published in Marine Ecology-Progress Series (2008)

Limpets, predominantly Patella vulgata, have been associated with damaged or receding canopies of Ascophyllum nodosum. Although the damage results from limpet grazing, the benefits that limpets gain from this behaviour are unclear as A. nodosum is thought to be well defended from grazers by anti-herbivore compounds. In this study, P. vulgata individuals were enclosed at densities between 80 and 320 m-2 at two sites within Strangford Lough. Limpet growth and limpet survival were compared between unsubsidised controls and treatments in which limpet diets were subsidised by fronds of A. nodosum. When subsidised, limpet residual growth rates were significantly higher and mortality was lower than in unsubsidised control treatments. Individual limpets consumed a similar amount of A. nodosum regardless of limpet density. Higher densities of limpets therefore consumed more A. nodosum per replicate. The effects of A. nodosum in maintaining limpet densities could resonate through sheltered rocky communities. The importance of a macroalgal subsidy in supporting limpet populations may have been underestimated or overlooked in earlier studies. Therefore, the extensive and productive macroalgal canopies that characterise many sheltered temperate rocky shores could be more sensitive to increased limpet abundances than previously thought.

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Davies, A.J., Johnson, M.P. & Maggs, C.A. (2008) “Subsidy by Ascophyllum nodosum increases growth rate and survivorship of Patella vulgata” Marine Ecology Progress Series, 366: 43-48.

http://dx.doi.org/10.3354/meps07453

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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.

http://dx.doi.org/10.1016/j.dsr.2008.04.010

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Published in JMBA UK 2008.

A three year study was undertaken during 2002 to 2004 from May to September to estimate abundance and density of harbour porpoises on the north coast of Anglesey, Wales, UK. There were no ecological data regarding the harbour porpoises in Anglesey waters so the ability to influence conservation measures was highly constrained.

Boat based transects using distance sampling techniques were applied so a robust estimate of density and abundance could be attained. The study area consisted of a block approximately 489 km2 extending from the east of Point Lynas to the west of South Stack on north coast of Anglesey. The study area was divided into 5 blocks consisting of 31 perpendicular transect lines to the shore. Each of the transect lines were surveyed 1–5 times by the end of the three year study.

Based on the assumption that g(0) = 1 the density of harbour porpoises for the 489 km2 study site was estimated to be 0.630 individuals/km2 (CV = 0.20) and the abundance is estimated to be 309 individuals (CV = 0.20). Heterogeneity in density and abundance was observed across the 5 blocks which showed Point Lynas and South Stack to have the highest densities. This distribution was closely associated to fine-scale oceanographic features which cause prey to be concentrated and may facilitate foraging for harbour porpoises. The study showed that Anglesey provides coastal habitats for the harbour porpoise and was the first study of this kind in North Wales, UK.

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Shucksmith R, Jones NH, Stoyle GW, Davies A, Dicks EF (2008) Abundance and distribution of the harbour porpoise ( Phocoena phocoena) on the north coast of Anglesey, Wales, UK. Journal of the Marine Biological Association of the United Kingdom Forthcoming:1-8.

http://dx.doi.org/10.1017/S0025315408002579

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Magnetic sensors have existed for many years and are widely used in different applications such as navigation systems, automation, position detection and current detection (amongst others). In this paper we explore a unique application of underwater magnetic sensing using a magneto-resistive sensor to monitor animal behaviour. Animal behaviour researchers have used several different techniques to study the behaviour of limpets. Most common are motographic methods using time-lapse photography. This technique is limited by low resolution, time consuming data analysis and sometimes an obscured field of view. Here, we present preliminary results from the use of a magneto-resistive sensor attached to the common limpet Patella vulgata. The (Honeywell HMC1052) 2-axis anisotropic magneto-resistive (AMR) sensor was fixed using epoxy putty to the shell of a limpet. The sensor has the capability to capture the limpet’s orientation with a resolution of 0.05°. This high resolution allows us to describe a range of behavioural responses which was not possible using earlier techniques. Limpet movement was truthed using time-lapse infra-red videography. Magneto-resistive sensors can quantify orientation behaviour, be used in extreme environments and provide superior data to qualitative and interpreted observations obtained from previous techniques. Several future developments may increase the applicability of this technique, such as using an artificial magnetic field to precisely locate animals at sub-GPS resolution.

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Wadke, P.M., Burrows, M.T., Meldrum, D. & Davies, A.J. (2007) “Using magneto-resitive sensors to monitor animal behaviour: a case study using limpets” Proceedings, Oceans 2007 MTS/IEEE Vancouver.

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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.

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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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