Northwest North Sea
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Scapa Bay in Orkney has been participating in the Marine Scotland Science Coastal Ecosystem Monitoring Programme since 2002. Samples are collected by Orkney Islands Council Marine Services and their input to the success of this programme is gratefully acknowledged.
The Orkney Isles are an archipelago of over 70 islands which lie just over 50 miles north of the Scottish mainland. They are separated from the mainland by the Pentland Firth, a tidally dynamic area where the waters of the Atlantic meet the waters of the North Sea.
The Scapa Bay monitoring site is located at Scapa Pier. Temperature is measured using a minilogger, and surface-water samples are taken for salinity and chemical analysis. A 10 m integrated tube sampler is used to collect samples for phytoplankton community analysis. Phytoplankton samples are preserved in Lugols iodine and analysed using the Utermöhl method (Utermöhl, 1958).
Temperature observes a strong seasonality at this site. The lowest temperatures are observed during spring (ca. 6°C) and the warmest temperatures towards late summer. The water temperature rarely exceeds 14°C at this site. Examination of the phytoplankton data reveals a similar pattern in the seasonality of the phytoplankton community as seen in other sites in the monitoring programme. During winter, phytoplankton growth is reduced. A spring Diatom bloom is succeeded by a summer community dominated by Dinoflagellates. An autumn Diatom bloom of larger Diatoms such as Rhizosolenia and Pseudo-nitzschia spp. type cells is also observed. An increase in the abundance of the Diatom Skeletonema has been observed since 2005. Since 2006, Diatoms have become more abundant throughout summer, increasing the Diatoms:Diatoms+Dinoflagellates ratio at this site. This summer Diatom community consists of centric Diatoms such as Thalassiosira and Chaetoceros.
A decrease in the abundance of the Dinoflagellate Ceratium has been observed until 2009, and more recently, blooms of Prorocentru cf. minimum have been observed during early summer. This site has also been subject to impacts from Karenia Mikimotoi blooms, with mortalities of fish and lugworms recorded during 2001 and 2006. A Karenia Mikimotoi bloom in 2003 resulted in significant mortalities of farmed fish in the area. Previous studies performed at this site have focused on the presence of harmful algal species and shellfish toxicity, as during the late 1990s, high concentrations of paralytic shellfish toxins were routinely recorded in shellfish tissue from Scapa Bay (Joyce, 2005; Bresnan et al., 2005, 2009).
Further information and links to the data collected at this site can be found at the Marine Scotland website ( http://www.scotland.gov.uk/Topics/marine/science/MSInteractive/Themes/Coastal).