Temporal development of coastal ecosystems in the Baltic Sea over the past two decades

Swedish Agency for Water Management, Gothenburg, Sweden*Corresponding author: tel: +46 10 478 41 44; e-mail: jens.olsson@slu.seOlsson,J.,Tomczak,M.T.,Ojaveer,H.,Ga˚rdmark,A.,Po˜lluma¨e,A.,Mu¨ller-Karulis,B.,Ustups,D.,Dinesen,G.E.,Peltonen,H.,Putnis,I.,Szymanek,L.,Simm,M.,Heikinheimo,O.,Gasyukov,P.,Axe,P.,andBergstro¨m,L.Temporaldevelopmentofcoastalecosystemsinthe BalticSea overthe pasttwo decades. – ICES Journal of Marine Science, doi: 10.1093/icesjms/fsv143.Received1 April 2015; revised 13 July 2015; accepted17 July 2015.Coastalareasareamongthemostbiologicallyproductiveaquaticsystemsworldwide,butfacestrongandvariableanthropogenicpressures.Fewstudieshave,however,addressedthetemporaldevelopmentofcoastalecosystemsinanintegratedcontext.Thisstudyrepresentsanassessmentofthe development over time in 13 coastal ecosystems in the Baltic Sea region during the past two decades. The study covers between two to sixtrophic levels per system and time-series dating back to the early 1990s. We applied multivariate analyses to assess the temporal developmentof biological ecosystem components and relate these to potential driving variables associated with changes in climate, hydrology, nutrientstatus, and fishing pressure. Our results show that structural change often occurred with similar timing in the assessed coastal systems.Moreover,in10ofthe13systems,adirectionaldevelopmentoftheecosystemcomponentswasobserved.Thevariablesrepresentingkeyecosystemcomponentsgenerallydifferedacrosssystems,duetonaturaldifferencesandlimitationtoavailabledata.Asaresultofthis,thecorrelationbetweenthetemporaldevelopmentofthebiologicalcomponentsineachareaandthedrivingvariablesassessedwastosomeextentarea-specific.However,change in nutrient status was acommon denominator of the variables most often associated with changes in the assessed systems. Our results,additionally, indicate existing strengths as well as future challenges in the capacity of currently available monitoring datato support integratedassessments and the implementation of an integrated ecosystem-based approach to the management of the Baltic Seacoastal ecosystems.Keywords: eutrophication,fish, integratedassessment, management, multivariate analyses, phytoplankton, zoobenthos, zooplankton.