Peter Henriksen

Late-glacial and Holocene palaeoceanography of the North Icelandic shelf

High-resolution gravity cores and box cores from the North Icelandic shelf have been studied for palaeoceanographic history based on lithological and biostratigraphical foramin- iferal data. Results from two outer shelf cores covering the last 13.6 k 14 C yr BP are presented in this paper. The sediments accumulated in north-south trending basins on each side of the Kolbeinsey Ridge at water depths of ca. 400 m. Sedimentation rates up to 1.5 m kyr -1 are observed during the Late-glacial and Holocene. The Vedde and Saksunarvatn tephras are present in the cores as well as the Hekla 1104. A new tephra, KOL-GS-2, has been identified and dated to 13.4 k 14 C yr BP, and another tephra, geochemically identical to the Borrobol Tephra, has been found at the same level. At present, the oceanographic Polar Front is located on the North Icelandic shelf, which experiences sharp oceanographic surface boundaries between the cold East Icelandic Current and the warmer Irminger Current. Past changes in sedimentological and biological processes in the study area are assumed to be related to fluctuations of the Polar Front. The area was deglaciated before ca. 14 kyr BP, but there is evidence of ice rafting up to the end of the GS-1 (Greenland Stadial 1, Younger Dryas) period, increasing again towards the end of the Holocene. Foraminiferal studies show a relatively strong GS-2 (pre-13 kyr BP) palaeo-Irminger Current, followed by severe cooling and then by unstable conditions during the remainder of the GI-1 (Greenland Interstadial 1, Bolling-Allerod) and GS-1 (Younger Dryas). Another cooling event occurred during the Preboreal before the Holocene current system was established at about 9 kyr BP. After a climatic optimum between 9 and 6 kyr BP the climate began to deteriorate and fluctuate. Copyright

Transitional and coastal waters ecological status assessment: advances and challenges resulting from implementing the European Water Framework Directive

The derivation, performance, sensitivity and inherent uncertainty of ecological quality indicators have become major topics in developing tools for the management of marine, transitional and coastal waters. In reviewing the advances in these waters, related to an ecological status assessment, we show the future challenges to be addressed within the European Water Framework Directive (WFD). Using new analyses carried out under the research project ‘Water Bodies in Europe: Integrative Systems to Assess Ecological status and Recovery’, we provide a complete set of assessments for the biological quality elements (BQEs) (phytoplankton, macroalgae-seagrasses, macroinvertebrates and fish) to be assessed, as well as the validation of existing indicators and multimetric indices and, in some cases, the development of new assessment indices. We show that these indices respond differently to different human pressures and they each have challenges in defining reference conditions against which future changes are judged. In investigating good ecological potential, as the response to heavily modified water bodies, we show that there are flaws in the Directive, not least in its definitions. Our analyses have also focussed on uncertainty in using the indices and we emphasise the problems of defining ecological class boundaries based on indices which themselves may be combined indices (multimetrics). The analysis shows that some of those multimetrics are redundant and/or are inter-correlated and thus may reduce the sensitivity in defining ecological class boundaries. If this is related to the drivers-pressures-state change-impacts-response approach then there are lessons for management measures aimed at achieving good ecological status and even the potential for legal challenges to decisions based on uncertain indices under the WFD. Hence, we conclude the continued need for advances in assessing pressures and gradients, and defining reference conditions for state change, index development, impact assessment and the validation of indices for each BQE.

Methods for detection of anatoxin-a(s) by liquid chromatography coupled to electrospray ionization-tandem mass spectrometry.

Anatoxin-a(s) is a potent irreversible inhibitor of the enzyme acetylcholinesterase with a unique N-hydroxyguanidine methylphosphate ester chemical structure. Determination of this toxin in environmental samples is hampered by the lack of specific methods for its detection. Using the toxic strain of Anabaena lemmermani PH-160 B as positive control, the fragmentation characteristics of anatoxin-a(s) under collision-induced dissociation conditions have been investigated and new LC-MS/MS methods proposed. Recommended ion transitions for correct detection of this toxin are 253>58, 253>159, 235>98 and 235>96. Chromatographic separation is better achieved under HILIC conditions employing a ZIC-HILIC column. This method was used to confirm for the first time the production of anatoxin-a(s) by strains of Anabaena oumiana ITEP-025 and ITEP-026. Considering no standard solutions are commercially available, our results will be of significant use for the correct identification of this toxin by LC-MS/MS.

Sources of uncertainty in assessment of marine phytoplankton communities

Characterisation of phytoplankton communities is important for classification of the ecological status of marine waters. In order to design a monitoring programme, it is important to know what degree of variation in the measurements occur at each level (water body, station and sample), so that resources can be spent in a way that maximise the precision of the measured parameters. Seven European water bodies were sampled to assess the variation in pigment concentrations and population densities attributed to water body, station and sample levels. It was found that the main proportion of the variation between pigment measurements was explained by the variation between stations (12–91% of variation) followed by the variation between water bodies (0–89% of variation). For measurements of population density, the main proportion of the variation between densities of cells recorded was explained by the variation between the taxonomists counting the samples (61%), whilst the main proportion of the variation between numbers of taxa recorded was explained by the variation between water bodies (83%). When the cell density of the nine dominant classes were analysed separately, the main proportion of variation was explained at the water body level for all but two class.