Liam Fernand

Seasonal evolution of the cold pool gyre, in the western Irish Sea

An extensive cruise program during 1994, 1995 and 1996 provided observations that describe the seasonal evolution of the three-dimensional density field in the western Irish Sea. A cold, dense pool flanked by strong nearbed density gradients was present from May until October. In spring, salinity had a dominant influence on the density structure but from June until October temperature controlled the density stratification. The trajectories of 55 satellite-tracked Argos drifters demonstrated the existence of the cyclonic circulation pattern that constitutes the western Irish Sea gyre and defined the gyres spatial extent. Several distinct recirculation paths were observed and the implications for planktonic organisms of the seasonal variability in the recirculation are discussed. Drifter speeds were in good agreement with geostrophic calculations based on the observed density field and with de-tided acoustic Doppler current profiler (ADCP) measurements. The dynamical significance of strong nearbed gradients (bottom fronts) is highlighted. The location of the dynamically significant baroclinicity below the level of wind mixing explains the persistence of the cold pool and cyclonic circulation until late October. The dataset described here is valuable for environmental management purposes and it facilitates testing of the prognostic capabilities of the present generation of density-advecting numerical models.

Spatial and seasonal changes of dissolved and particulate organic C in the North Sea

Sampling of the central region of the North Sea was carried out to study the spatial and seasonal changes of dissolved and particulate organic C (DOC and POC, respectively). The surface waters were collected during four cruises over a year (Autumn 2004–Summer 2005). DOC and POC concentrations were measured using high temperature catalytic oxidation methods. The surface water concentrations of DOC and POC were spatially and temporally variable. There were significantly different concentrations of DOC and POC between the inshore and offshore waters in winter and summer only, with no clear trend in autumn and spring. Highest mean concentrations of DOC were measured in spring with lower and similar mean concentrations for other seasons. POC showed a clear seasonal cycle throughout the year with highest surface mean concentrations found in autumn and spring, but lowest in winter and summer. The DOC distributions during autumn and spring were strongly correlated with chlorophyll suggesting extracellular release from phytoplankton was an important DOC source during these two seasons. The lower concentrations of DOC in summer were probably due to the heterotrophic uptake of labile DOC. The seasonal changes in the C:N molar ratios of surface DOM (dissolved organic matter) resulted in higher mean C:N molar ratios in spring and lower ratios in winter. These high ratios may indicate nutrient limitation of heterotrophic uptake immediately after the spring bloom. There is limited data available for DOC cycling in these productive shelf seas and these results show that DOC is a major component of the C cycle with partial decoupling of the DOC and DON cycling in the central North Sea during the spring bloom.

A Review of the Tools Used for Marine Monitoring in the UK: Combining Historic and Contemporary Methods with Modeling and Socioeconomics to Fulfill Legislative Needs and Scientific Ambitions

Marine environmental monitoring is undertaken to provide evidence that environmental management targets are being met. Moreover, monitoring also provides context to marine science and over the last century has allowed development of a critical scientific understanding of the marine environment and the impacts that humans are having on it. The seas around the UK are currently monitored by targeted, impact-driven, programmes (e.g. fishery or pollution based monitoring) often using traditional techniques, many of which have not changed significantly since the early 1900s. The advent of a new wave of automated technology, in combination with changing political and economic circumstances, means that there is currently a strong drive to move towards a more refined, efficient, and effective way of monitoring. We describe the policy and scientific rationale for monitoring our seas, alongside a comprehensive description of the types of equipment and methodology currently used and the technologies that are likely to be used in the future. We contextualise the way new technologies and methodologies may impact monitoring and discuss how whole ecosystems models can give an integrated, comprehensive approach to impact assessment. Furthermore, we discuss how an understanding of the value of each data point is crucial to assess the true costs and benefits to society of a marine monitoring programme.