Climate change, impacts and vulnerability in Europe ... - MemoFin.fr

Climate impacts on environmental systems3.1.6 Distribution of marine speciesRelevanceChanges in the distribution of organisms are one ofthe key indicators of marine climate change impacts.Distribution maps from the North-east Atlantic areused as one part of this indicator to demonstratelarge-scale changes at the decadal scale. The secondpart of this indicator describes the ratio betweena warm-water species (Calanus helgolandicus) anda cold-water species (Calanus finmarchicus) in theNorth Sea on an annual basis (see Figure 3.5). In theeastern Mediterranean Sea, the introduction of warmand tropical alien species from the Red Sea hasbeen exacerbated by observed warming, leading toa 150 % increase in the annual mean rate of speciesentry after 1998 (Raitsos et al., 2010).Changes in marine plankton can trigger furthereffects on marine and terrestrial ecosystems. Forexample, increases in the surface temperature ofthe North Sea in recent decades have triggeredestablishment of warm-water swimming crabs,which in turn allowed establishment of colonies oflesser black-backed gulls in Belgium and northernFrance, with expected follow-on impacts onterrestrial ecosystems through their fertilisation ofterrestrial soils (Luczak et al., 2012).Past trendsIncreases in regional sea temperatures havetriggered a major northward movement ofwarmer‐water plankton in the North-east Atlanticand a similar retreat of colder-water planktonto the north. This northerly movement is about10 ° latitude (1 100 km) over the past 40 years (amean poleward movement of between 200 and250 km per decade), and there appears to havebeen an acceleration since 2000 (Beaugrand, 2009).Recently, a Norwegian study showed even fasterrates of northward movement between 1997 and2010. Out of about 1 600 benthic marine speciesfound in coastal waters of southern Norway, 565species had expanded their distribution northwardsalong the coast, at rates of 500–800 km per decade(Brattegard, 2011). These rates are much faster thanany other documented terrestrial study.ProjectionsFurther changes in the distribution of marine speciesare expected, with projected further climate change,but quantitative projections are not available.Key messages: 3.1.6 Distribution of marine species• Increases in regional sea temperatures have triggered a major northward expansion of warmer-waterplankton in the North-east Atlantic and a northward retreat of colder-water plankton. This northerlymovement is about 10 ° latitude (1 100 km) over the past 40 years, and it seems to have acceleratedsince 2000.• Sub-tropical species are occurring with increasing frequency in European waters, and sub-Arctic speciesare receding northwards.• Further changes in the distribution of marine species are expected, with projected further climatechange, but quantitative projections are not available.Climate change, impacts and vulnerability in Europe 201299