title: Indicator Properties of Baltic Zooplankton for Classification of Environmental Status within Marine Strategy Framework Directive.
abstract: The European Marine Strategy Framework Directive requires the EU Member States to estimate the level of anthropogenic impacts on their marine systems using 11 Descriptors. Assessing food web response to altered habitats is addressed by Descriptor 4 and its indicators, which are being developed for regional seas. However, the development of simple foodweb indicators able to assess the health of ecologically diverse, spatially variable and complex interactions is challenging. Zooplankton is a key element in marine foodwebs and thus comprise an important part of overall ecosystem health. Here, we review work on zooplankton indicator development using long-term data sets across the Baltic Sea and report the main findings. A suite of zooplankton community metrics were evaluated as putative ecological indicators that track community state in relation to Good Environmental Status (GES) criteria with regard to eutrophication and fish feeding conditions in the Baltic Sea. On the basis of an operational definition of GES, we propose mean body mass of zooplankton in the community in combination with zooplankton stock measured as either abundance or biomass to be applicable as an integrated indicator that could be used within the Descriptor 4 in the Baltic Sea. These metrics performed best in predicting zooplankton being in-GES when considering all datasets evaluated. However, some other metrics, such as copepod biomass, the contribution of copepods to the total zooplankton biomass or biomass-based Cladocera: Copepoda ratio, were equally reliable or even superior in certain basin-specific assessments. Our evaluation suggests that in several basins of the Baltic Sea, zooplankton communities currently appear to be out-of-GES, being comprised by smaller zooplankters and having lower total abundance or biomass compared to the communities during the reference conditions; however, the changes in the taxonomic structure underlying these trends vary widely across the sea basins due to the estuarine character of the Baltic Sea.
authors.affiliation: Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden.
authors.forename: Elena
authors.identifier: http://orcid.org/0000-0002-4192-6956
authors.initials: E
authors.lastname: Gorokhova
authors.affiliation: Finnish Environment Institute, Marine Research Center, Helsinki, Finland.
authors.forename: Maiju
authors.initials: M
authors.lastname: Lehtiniemi
authors.affiliation: Leibniz Institute for Baltic Sea Research, Rostock-Warnemünde, Rostock, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Postel
authors.affiliation: Department of Fish Resources Research, Institute of Food Safety, Animal Health and Environment, Riga, Latvia.
authors.forename: Gunta
authors.initials: G
authors.lastname: Rubene
authors.affiliation: Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden.
authors.forename: Callis
authors.initials: C
authors.lastname: Amid
authors.affiliation: Open Access Centre for Marine Research, Klaipėda University, Klaipeda, Lithuania.
authors.forename: Jurate
authors.initials: J
authors.lastname: Lesutiene
authors.affiliation: Finnish Environment Institute, Marine Research Center, Helsinki, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Uusitalo
authors.affiliation: Latvian Institute of Aquatic Ecology, Riga, Latvia.
authors.forename: Solvita
authors.initials: S
authors.lastname: Strake
authors.affiliation: Lithuanian Environmental Protection Agency, Klaipėda, Lithuania.
authors.forename: Natalja
authors.initials: N
authors.lastname: Demereckiene
mesh_terms: D000818:Animals; D001454:Baltic States; D044822:Biodiversity; D018533:Biomass; D033342:Copepoda / Q000145:classification*; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D005068:Eutrophication; D020387:Food Chain; D009792:Oceans and Seas; D015048:Zooplankton / Q000145:classification* / Q000302:isolation & purification*