Natural iron fertilization of the Atlantic sector of the Southern Ocean by continental shelf sources of the Antarctic Peninsula

In large parts of the Southern Ocean, primary production is limited due to shortage of iron (Fe). We measured vertical Fe profiles in the western Weddell Sea, Weddell-Scotia Confluence, and Antarctic Circumpolar Current (ACC), showing that Fe is derived from benthic Fe diffusion and sediment resuspension in areas characterized by high turbulence due to rugged bottom topography. Our data together with literature data reveal an exponential decrease of dissolved Fe (DFe) concentrations with increasing distance from the continental shelves of the Antarctic Peninsula and the western Weddell Sea. This decrease can be observed 3500 km eastward of the Antarctic Peninsula area, downstream the ACC. We estimated DFe summer fluxes into the upper mixed layer of the Atlantic sector of the Southern Ocean and found that horizontal advection dominates DFe supply, representing 54 ± 15% of the total flux, with significant vertical advection second most important at 29 ± 13%. Horizontal and vertical diffusion are weak with 1 ± 2% and 1 ± 1%, respectively. The atmospheric contribution is insignificant close to the Antarctic continent but increases to 15 ± 10% in the remotest waters (>1500 km offshore) of the ACC. Translating Southern Ocean carbon fixation by primary producers into biogenic Fe fixation shows a twofold excess of new DFe input close to the Antarctic continent and a one-third shortage in the open ocean. Fe recycling, with an estimated “fe” ratio of 0.59, is the likely pathway to balance new DFe supply and Fe fixation.

The potential of offshore windfarms to act as marine protected areas – A systematic review of current evidence

As offshore windfarm (OWF) construction in the UK is progressing rapidly, monitoring of the economic and ecological effects of these developments is urgently needed. This is to enable both spatial planning and where necessary mitigation in an increasingly crowded marine environment. One approach to mitigation is co-location of OWFs and marine protected areas (MPAs). This systematic review has the objective to inform this co-location proposal and identify areas requiring further research. A limited number of studies addressing marine renewable energy structures and related artificial structures in coastal waters were found. The results of these studies display a change in species assemblages at artificial structures in comparison to naturally occurring habitats. An increase in hard substrata associated species, especially benthic bivalves, crustaceans and reef associated fish and a decrease in algae abundance were the dominant trends. Assemblages associated with complex concrete structures revealed greater similarity to natural hard substrata compared to those around steel structures. To consider marine renewable energy sites, especially large scale OWFs as MPAs, the dissimilar nature of assemblages on the structures themselves to natural communities should be considered. However positive effects were recorded on the abundance of commercially important crustacean species. This suggests potential for incorporation of OWFs as no fishing, or restricted activity zones within a wider MPA to aid fisheries augmentation. The limited available evidence highlights a requirement for significant further research involving long term monitoring at a variety of sites to better inform management options.

Natural bedfellows or worlds apart? Research, conservation and the blue growth agenda

There is now a concerted effort to grow the ‘blue economy’ which in Europe is estimated at being worthy around €500 a year. The relevance of marine research for the blue-growth agenda is often linked to the degree to which the research is ‘applied’, links to so called ‘blue-skies’ research are less clear. Conservation science is often seen even more negatively with conservation being seen as a hindrance to economic development. The history of blue-skies marine research and conservation science tells a very different story however suggesting the future rests on bringing these elements together.