Sargassum muticum

Not all introduced (invasive) species in a region will spread from a single point of introduction. Long-distance dispersal or further introductions can obscure the pattern of spread, but the regional importance of such processes is difficult to gauge. These difficulties are further compounded when information on the multiple scale process of invasive species range expansion is reduced to one-dimensional estimates of spread (e.g. km yr⁻¹). We therefore compared the results of two different metrics of range expansion: maximum linear rate of spread and accumulation of occupied grid squares (50 × 50 km) over time. An analysis of records for 54 species of introduced marine macrophytes in the Mediterranean and northeast Atlantic revealed cases where the invasion process was probably missed (e.g. Atlantic Bonnemaisonia hamifera) and suggested cases of secondary introductions or erratic jump dispersal (Dasysiphonia sp. and Womersleyella setacea). A majority of species analysed showed evidence for an accumulation of invaded sites without a clear invasion front. Estimates of spread rate are increasing for more recent introductions. The increase is greater than can be accounted for by temporally varying search effort and implies a historical increase in vector efficiency and/or a decreased resistance of native communities to invasion.

In press in the journal, Proceedings of the Royal Society Series B: Biological Sciences.

Full citation

Mineur F, Davies AJ, Maggs CA, Verlaque M, Johnson MP (In press) Fronts, jumps and secondary introductions suggested as different invasion patterns in marine species, with an increase in spread rates over time. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2010.0494

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Lophelia pertusa at VK826

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 (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.

In press in Deep Sea Research vol 1.

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. (in press) “Short-term environmental variability in cold-water coral habitat at Viosca Knoll, Gulf of Mexico.” Deep-sea Research Vol 1. DOI: 10.1016/j.dsr.2009.10.012.

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Observatory with a Porpoise

As part of a collaboration with Adrian Glover of the NHM, Kim Last of SAMS and Thomas Dahlgren of Gothenburg we have been working on developing underwater observatories to watch the colonisation and degradation of whale bones. Our camera was recently released live on the internet as part of the launch of the NHMs Darwin Centre.

Press release follows

Scientists, including those from the Natural History Museum, have developed the world’s first underwater observatory connected to the internet, creating a window into the ocean, one of the least-studied environments on our planet.

Live images are streamed online from the observatory under the sea, which means scientists anywhere in the world are now able to study processes in real-time, helping them better understand how marine ecosystems work.

Electron micrograph of Osedax mucofloris, the marine worm species Adrian Glover discovered in 2005 and hopes to study using the underwater observatory.

Natural History Museum marine biologist Adrian Glover showed the live stream of the observatory at the Museum’s grand opening of the new Darwin Centre last week with special guests Prince William and Sir David Attenborough. The state-of-the-art building lets the public get a glimpse of some of the important science research that happens at the Museum.

The system was created by a team from the Natural History Museum, University of Gothenburg, Maritime Museum and Aquarium Gothenburg, Scottish Association of Marine Science, OceanLab Aberdeen, and Bangor University.

Current underwater studies

The observatory is currently 30m underwater in a fjord on the west coast of Sweden at the Sven Loven Centre for Marine Sciences. It is beaming images of a community of scavenging creatures living on the remains of a dead whale.

‘Even something simple like the decomposition of a small whale in shallow water is very poorly known,’ says Glover. ‘Until now, we had to make do with ‘one-off’ visits using submersibles, remotely operated-vehicles or scuba divers.’

Glover is currently studying the feeding behaviour of scavenging animals that feed on the carcass. He is also hoping to study the colonisation of the bones by the bone-eating worms from the genus Osedax, one species of which he discovered in 2005.

This hut contains the observatory 'node', a communications hub, which is powered and connected to the internet by fibre-optic cables.

How the observatory works

The underwater observatory is made up of a video camera and instruments that are mounted onto a frame. Video data is sent live along cables to the observatory ‘node’, a type of communications hub that is in a hut on a nearby island. The node is powered and connected to the internet by fibre-optic cables.

Technology advances in the cabling and underwater instruments enabled this system to work whereas a few years ago it wouldn’t have been possible. However, there were some hurdles to overcome along the way, from problems with computer software and flooding of the camera housing, to a sudden infestation of barnacles!

Future use of observatory

The observatory is designed so that it can be used in potentially much greater ocean depths. ‘If we are successful in raising funds, we would like to deploy our observatory in the deep sea using a remotely-operated vehicle’ says Glover.

‘We know even less about processes in the deep sea, and a network of observatories like these could revolutionise our perception of the marine environment.’

View an amazing time-lapse video of the observatory below:

Take a look at the camera: http://www.kmf.gu.se/bildcenter/kamera2/

SAMS/Bangor Mini-lander

With my long standing collaborator Kim Last from SAMS and MSc student Harri Condie, we recently conducted a field trip to Sabellaria spinulosa habitats in the Wash. Sabellaria spinulosa is a polychaete worm that builds dwelling tubes out of suspended particles. As part of a project with Kim, funded by the Aggregate Levy, we are working to better understand these amazing reef-building creatures.

Armed with the best gear we could find at short-notice, we constructed a mini-lander system to be deployed near a S. spinulosa reef. We equipped the system with sensors that included a laser particle sizer set to provide information on the particle supply in the region, a current meter, temperature loggers and a CTD system logging not only temperature, salinity and depth but also light attenuation and dissolved oxygen.

Kim with the VideoRay ROV

We left the lander on the seafloor for 24 hours, providing a valuable insight into the particles that may be supplied to the S. spinulosa reef. To supplement this, we also placed out sediment traps on the amazing intertidal reef at Scotsman’s Sled. These traps are basically tubes that allow sediment to settle to the bottom, we then take the sediment back to the lab and look at the type and quantity of particles, including any organic food particles that land into the trap. These particles allow us to verify the readings from the particle sizer but also provide a vital clue to why S. spinulosa is found in that area.

We were out with the Eastern Sea Fisheries Joint Comittee on board their boat the Three Counties. They even let us have a go with their amazing little ROV, a VideoRay. Seriously, we’re thinking that we could do with one! Many thanks to ESFJC and the crew for supporting our research.

We’ve only been back a few days, so our data is still being downloaded off our instruments. But these observations will hopefully be the first of many, as we attempt to determine the underlying environmental controls for S. spinulsa. This work was related to the MEPF/ALSF project (MEPF 08/p76), where we are using our novel VoRT tanks to better understand the impact of aggregate dredging on a range of different species.

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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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 Journal of Experimental Marine Biology and Ecology 370.

Full citation

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 370, 35-40.

http://dx.doi.org/10.1016/j.jembe.2008.11.015

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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.

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 JMBA UK 2009.

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.

Full citation

Shucksmith R, Jones NH, Stoyle GW, Davies A, Dicks EF (2009) 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, 89(5), 1051-1058.

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

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