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Scalloway, United Kingdom

Gray D.R.,Marine Center | Williams G.A.,University of Hong Kong
Journal of Experimental Marine Biology and Ecology | Year: 2010

The high shore limpet, Cellana grata, forages whilst awash, moving upshore with the rising tide and retreating downshore on the ebbing tide to become inactive in refuges. Spraying inactive, emersed individuals with seawater at low tide invokes a locomotory response, with limpets moving up the shore. Controlled laboratory experiments under continuous white or red light (to simulate light or dark periods respectively) and continuous emersion, immersion or seawater spray showed that C. grata possesses a free-running endogenous rhythm of locomotor activity. This rhythm was maintained over 30. days in continuous seawater spray and white light. Maximum entropy spectral analysis (MESA) revealed two major components to this rhythm, at 7.2. h and 12.4. h. The 12.4. h component is of a circatidal nature and appears to initiate activity, allowing individuals to anticipate immersion by the incoming tide, although this clock can be over-ridden by strong wave splash or spraying vigorously with seawater. The 7.2. h period, however, was the most significant component and is suggested to act as a stopwatch enabling the limpet to assess the duration of each foraging excursion in order to prevent being stranded at the wrong height on the shore. The environmental stimulus for both components of the endogenous rhythm in C. grata appears to be the time of first exposure to wave wash from the incoming tide. C. grata, therefore, has behavioural rhythms entrained to initiate and also terminate activity, which play a role in the limpet maintaining a fixed vertical level on the shore when inactive. © 2010 Elsevier B.V. Source

The decapod Hippolyte prideauxiana is a cryptic commensal of the crinoid Antedon bifida, giving rise to its common name 'the feather star shrimp'. In 2010 and 2013 H. prideauxiana was recorded in the Shetland Islands and the Orkney Islands ('north isles'), northern Scotland. These observations widen the known geographical distribution of this species by 400 km north from the west coast of Scotland where it was first recorded in 1997. Whilst it is possible that these new records are the result of a range expansion due to climate change it is more likely that this species has been overlooked due to its cryptic coloration, limited awareness of this species and increase in survey effort in the north of Scotland using SCUBA. © Marine Biological Association of the United Kingdom, 2014. Source

Ni Chualain C.,Mayo Institute of Technology, Galway | Robinson M.,Marine Center
ICES Journal of Marine Science | Year: 2011

Endoparasitic dinoflagellates of the genus Hematodinium have recently gained attention as significant pathogens of the brown crab Cancer pagurus in Ireland. Patent infections, which are characterized by a hyperpigmented carapace and moribund condition, are limited to the discrete periods when macroscopic identification is possible. Three methods are assessed for diagnosing Hematodinium sp. infections in brown crab at the times when macroscopic identification is not always possible. Haemolymph smears, histological sections of gill, heart, midgut, hepatopancreas, muscle, and gonad, and a polymerase chain reaction (PCR) assay provided virtually equivalent accuracy in gauging infection prevalence, regardless of season. Sequences of PCR amplicons from the 18S ribosomal RNA gene confirmed the identity of the parasite as belonging to the genus Hematodinium. Infection intensity values (<1-87%) obtained from haemolymph smears underscored infection levels within tissues, 90% of which contained advanced levels of infection. Alterations to tissues of infected crabs included haemocytopoenia, oedema, which caused dilation of the haemal sinuses resulting in pressure necrosis to the connective tissues around the oocytes, myocardial bundles, and hepatopancreatic tubules. The claw muscle of infected animals contained the fewest parasites. © 2011 International Council for the Exploration of the Sea. Source

Automatic identification system (AIS) is becoming increasingly popular with marine vessels providing accessible, up-to-date information on vessel activity in the marine environment. Although AIS has been utilised in several different fields to address specific questions, no published work has outlined the potential of AIS as a tool for a wide range of industries and users of the marine environment such as spatial planning, developments, and local marine industries (e.g. fisheries). This work demonstrates a procedure for processing, analysing, and visualisation of AIS data with example outputs and their potential uses. Over 730. 000 data points of AIS information for 2013 from around Shetland were processed, analysed, and mapped. Tools used included density mapping, vessel tracks, interpolations of vessel dimensions, and ship type analysis. The dataset was broken down by sector into meaningful and usable data packets which could also be analysed over time. Density mapping, derived from both point and vessel track data, proved highly informative but were unable to address all aspects of the data. Vessel tracks showed variation in vessel routes, especially around island groups. Additional uses of AIS data were addressed and included risk mapping for invasive non-native species, fisheries, and general statistics. Temporal variation of vessel activity was also discussed. © 2015 Elsevier Ltd. Source

Tweddle J.F.,Marine Center | Sharples J.,University of Liverpool | Sharples J.,National Oceanography Center | Palmer M.R.,National Oceanography Center | And 2 more authors.
Progress in Oceanography | Year: 2013

Patches of enhanced chlorophyll a (Chl) concentrations within the thermocline were observed over the slopes of several banks in the Celtic Sea. The turbulent mixing of nutrients from the bottom water into the thermocline was found to be greatly enhanced over the slope of a bank (up to 52mmolnitratem-2day-1), compared to over nearby flat seafloor (~2mmolnitratem-2day-1). This increased nutrient supply, forced by locally generated lee waves and internal mixing, is greater than nitrate supplies to the productive tidal mixing fronts or to the shelf edge. We hypothesize this nutrient flux promotes an increase in phytoplankton growth in the thermocline over and downstream of shelf sea banks, contributing to the horizontal patchiness in the thermocline Chl signal. The persistence of the strong biological response to mixing at the bank, combined with the ubiquity of shelf sea banks, suggests these bathymetric features have wide importance for "new" primary production in shelf seas. © 2013 The Authors. Source

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