| 1. |
- Ammar, Yosr, et al.
(författare)
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The rise of novelty in marine ecosystems : The Baltic Sea case
- 2021
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 27:7, s. 1485-1499
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Tidskriftsartikel (refereegranskat)abstract
- Global environmental changes have accelerated at an unprecedented rate in recent decades due to human activities. As a consequence, the incidence of novel abiotic conditions and biotic communities, which have been continuously emerging in the Earth system, has rapidly risen. Despite growing attention to the incidence and challenges posed by novelty in terrestrial ecosystems, novelty has not yet been quantified in marine ecosystems. Here, we measured for the rate of novelty (RoN) in abiotic conditions and community structure for three trophic levels, i.e., phytoplankton, zooplankton, and fish, in a large marine system - the Baltic Sea. We measured RoN as the degree of dissimilarity relative to a specific spatial and temporal baseline, and contrasted this with the rate of change as a measure of within-basin change over time. We found that over the past 35 years abiotic and biotic RoN showed complex dynamics varying in time and space, depending on the baseline conditions. RoN in abiotic conditions was smaller in the open Central Baltic Sea than in the Kattegat and the more enclosed Gulf of Bothnia, Gulf of Riga, and Gulf of Finland in the north. We found a similar spatial pattern for biotic assemblages, which resulted from changes in composition and stock size. We identified sea-surface temperature and salinity as key drivers of RoN in biotic communities. Hence, future environmental changes that are expected to affect the biogeochemistry of the Baltic Sea, may favor the rise of biotic novelty. Our results highlighted the need for a deeper understanding of novelty development in marine ecosystems, including interactions between species and trophic levels, ecosystem functioning under novel abiotic conditions, and considering novelty in future management interventions.
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| 2. |
- Beaugrand, G., et al.
(författare)
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Synchronous marine pelagic regime shifts in the Northern Hemisphere
- 2015
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 370:1659
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Tidskriftsartikel (refereegranskat)abstract
- Regime shifts are characterized by sudden, substantial and temporally persistent changes in the state of an ecosystem. They involve major biological modifications and often have important implications for exploited living resources. In this study, we examine whether regime shifts observed in 11 marine systems from two oceans and three regional seas in the Northern Hemisphere (NH) are synchronous, applying the same methodology to all. We primarily infer marine pelagic regime shifts from abrupt shifts in zooplankton assemblages, with the exception of the East Pacific where ecosystem changes are inferred from fish. Our analyses provide evidence for quasi-synchronicity of marine pelagic regime shifts both within and between ocean basins, although these shifts lie embedded within considerable regional variability at both year-to-year and lower-frequency time scales. In particular, a regime shift was detected in the late 1980s in many studied marine regions, although the exact year of the observed shift varied somewhat from one basin to another. Another regime shift was also identified in the mid-to late 1970s but concerned less marine regions. We subsequently analyse the main biological signals in relation to changes in NH temperature and pressure anomalies. The results suggest that the main factor synchronizing regime shifts on large scales is NH temperature; however, changes in atmospheric circulation also appear important. We propose that this quasi-synchronous shift could represent the variably lagged biological response in each ecosystem to a large-scale, NH change of the climatic system, involving both an increase in NH temperature and a strongly positive phase of the Arctic Oscillation. Further investigation is needed to determine the relative roles of changes in temperature and atmospheric pressure patterns and their resultant teleconnections in synchronizing regime shifts at large scales.
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| 3. |
- Bergström, Lena, et al.
(författare)
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Interim Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB) : 18-22 April 2016 Helsinki, Finland
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB) meeting was held in Helsinki (Finland), 18-22 April 2016. The meeting was attended by 26 participants from five countries and chaired by Laura Uusitalo, Fin-land, Saskia Otto, Germany, Martin Lindegren, Denmark, and Lena Bergström, Swe-den. This was the first year of the new three-year Terms of Reference (ToR) for WGIAB. The main working activities in 2016 were to A) develop the trait-based ap-proach of understanding the ecosystem function, and B) explore the social-ecological system, including indicator development, revising the conceptual model, and devel-oping case studies. As a primary outcome of the ToR A, we built on our previous work on integrated ecosystem assessments (IEAs) in the Baltic Sea, but extended it beyond considering changes in abundances of a few dominant species, to accounting for community-wide changes in a number of key traits across multiple trophic levels. These traits represent various ecosystem functions upon which we derive important ecosystem services. By investigating temporal changes in the community weighted mean traits of phyto-plankton, zooplankton, zoobenthos, and fish, we demonstrated whether trait reor-ganizations at the level of entire communities occurred in the Central Baltic Sea as a result of the 1980s regime shift. Using in total 29 traits combined for all groups we found indications of two breakpoints across all four taxonomic groups over the last decades, i.e. one around 1990 and one around 2000. Further work will focus on ex-ploring the nature of the changes in trait composition and on standardizing the num-ber of traits and data types (i.e. binary, continuous or categorical) across taxonomic group.In addition, we collected data on key functional groups and abiotic variables in all main sub-basins of the Baltic Sea, setting the stage for a cross-regional comparison of temporal patterns and trends in lower trophic level in the face of recent develop-ments in climate-related drivers.With reference to Tor B, to explore how social indicators could be used in parallel with biological indicators in an integrated assessment framework, we developed a conceptual model of interrelationships between ecosystem and society. We used the model as a basis for mapping factors to be accounted for in the ecosystem-based management using the Baltic salmon and clupeid species as case studies. The models depict 1) the structure of the foodweb relevant to the target species, 2) the key com-munity level and population traits that contribute to the state of the species, 3) main pressures affecting the foodweb and their effects on the species, 4) key management measures, and 5) benefits that the species can produce for society.To support the development of Ecosystem Overview the group members evaluated the probability of occurrence and the magnitude of the effect of 15 pressures occur-ring in the Baltic Sea. The top five pressures identified were input of nutrients, in-creased temperature, decreased salinity, input of hazardous substances, and input or spread of non-indigenous species.The work will continue intersessionally and the next meeting of WGIAB is planned to be held in Lisbon, Portugal, back-to-back with WGCOMEDA and WGEAWESS.
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| 4. |
- Bergström, Lena, et al.
(författare)
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Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB)
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea(WGIAB) was established in 2007 as a forum for developing and combining ecosystembasedmanagement efforts for the Baltic Sea. The group intends to serve as a scientificcounterpart and support for the ICES Baltic Fisheries Assessment Working Group(WGBFAS) as well as for efforts and projects related to Integrated Ecosystem Assessments(IEA) within ICES and HELCOM. The group works in cooperation with similargroups within the ACOM/SCICOM Steering Group on Integrated Ecosystem Assessments(SSGIEA).The 2015 WGIAB meeting was held in Cádiz, Spain, from 9–13 March, back-to-backwith the meeting of its counterpart in the Working Group on Ecosystem Assessmentof Western European Shelf Seas (WGEAWESS). The meetings had joint sessions as wellas WG specific work, and some participants effectively participated in both meetings.The WGIAB meeting was attended by 27 participants from nine countries. The meetingwas chaired by Christian Möllmann, Germany, Laura Uusitalo, Finland and Lena Bergström,Sweden.This was the last year of the ongoing three-year Terms of Reference (ToR) for WGIAB.The main working activities in 2015 were to i) conduct studies on Baltic Sea ecosystemfunctioning with the goal to publish case studies from different parts of the Baltic Seain peer-reviewed journals, ii) work on the demonstration exercise to develop ecosystem-based assessment and advice for Baltic fish stocks focusing on cod (DEMO) withmultiple approaches, iii) plan further how to integrate the social and economic aspectsmore tightly in the WGIAB work, and iv) discuss the future focus and format of theWGIAB work.The Baltic ecosystem functioning activity focused on identifying and exploring keytrends and linkages in the Baltic Sea foodweb. This was pursued by presentation andfurther discussion of ongoing intersessional work on foodweb modelling and integratedanalyses, and by exercises to develop conceptual models Baltic Sea foodwebsand the links to ecosystem function. Long-term monitoring datasets on the abiotic andbiotic parts of the Baltic Sea Proper ecosystem were updated for use in the continuedwork to develop environmental indicators for fisheries and marine management.The focus of the DEMO 3 (DEMOnstration exercise for Integrated Ecosystem Assessmentand Advice of Baltic Sea cod) was on finding a way to use the results from theDEMO1 and DEMO2 workshops in short and midterm projections/scenarios of Balticcod dynamics based on different types of modelling, as well as designing methodologyand modelling data for practical implementation of Integrated Advice for Baltic cod.The WGIAB was positively inclined towards including social and economic aspectsinto the integrated assessment. Openings to this path were provided by presentationon ongoing project work, and discussing their linkages to ecological aspects. It wasseen as crucial that experts on social and economic analysis should be included andtake an active part in the future work of the group.The group concluded that its upcoming work should focus more closely on functionaldiversity, which was identified as a recurring issue in the Baltic Sea. This approach wasalso identified as a useful connection point between scientific and management aspectsin order for the group to continue serving as a forum for developing ecosystem-basedmanagement efforts in the Baltic Sea. A focus on functional diversity was also seen as2 | ICES WGIAB REPORT 2015a potentially feasible way of bringing together management aspects for different sectors,by linking to ecosystem services concepts.The group proposed Saskia Otto, Germany and Martin Lindegren, Denmark as newincoming Chairs, together with Lena Bergström, Sweden and Laura Uusitalo, Finland.Having four Chairs is justified due to the wide scope of the group's work, as well asthe increased work load due to the planned new foci.
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| 5. |
- Downing, Andrea S., et al.
(författare)
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Zooming in on size distribution patterns underlying species coexistence in Baltic Sea phytoplankton
- 2014
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 17:10, s. 1219-1227
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Tidskriftsartikel (refereegranskat)abstract
- Scale is a key to determining which processes drive community structure. We analyse size distributions of phytoplankton to determine time scales at which we can observe either fixed environmental characteristics underlying communities structure or competition-driven size distributions. Using multiple statistical tests, we characterise size distributions of phytoplankton from 20-year time series in two sites of the Baltic Sea. At large temporal scales (5-20 years), size distributions are unimodal, indicating that fundamental barriers to existence are here subtler than in other systems. Frequency distributions of the average size of the species weighted by biovolume are multimodal over large time scales, although this is the product of often unimodal short-term (<1 year) patterns. Our study represents a much-needed structured, high-resolution analysis of phytoplankton size distributions, revealing that short-term analyses are necessary to determine if, and how, competition shapes them. Our results provide a stepping-stone on which to further investigate the intricacies of competition and coexistence.
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| 6. |
- Kadin, Martina, et al.
(författare)
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Trophic Interactions, Management Trade-Offs and Climate Change : The Need for Adaptive Thresholds to Operationalize Ecosystem Indicators
- 2019
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745.
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Tidskriftsartikel (refereegranskat)abstract
- Ecosystem-based management (EBM) is commonly applied to achieve sustainable use of marine resources. For EBM, regular ecosystem-wide assessments of changes in environmental or ecological status are essential components, as well as assessments of the effects of management measures. Assessments are typically carried out using indicators. A major challenge for the usage of indicators in EBM is trophic interactions as these may influence indicator responses. Trophic interactions can also shape trade-offs between management targets, because they modify and mediate the effects of pressures on ecosystems. Characterization of such interactions is in turn a challenge when testing the usability of indicators. Climate variability and climate change may also impact indicators directly, as well as indirectly through trophic interactions. Together, these effects may alter interpretation of indicators in assessments and evaluation of management measures. We developed indicator networks - statistical models of coupled indicators - to identify links representing trophic interactions between proposed food-web indicators, under multiple anthropogenic pressures and climate variables, using two basins in the Baltic Sea as a case study. We used the networks to simulate future indicator responses under different fishing, eutrophication and climate change scenarios. Responsiveness to fishing and eutrophication differed between indicators and across basins. Almost all indicators were highly dependent on climatic conditions, and differences in indicator trajectories > 10% were found only in comparisons of future climates. In some cases, effects of nutrient load and climate scenarios counteracted each other, altering how management measures manifested in the indicators. Incorporating climate change, or other regionally non-manageable drivers, is thus necessary for an accurate interpretation of indicators and thereby of EBM measure effects. Quantification of linkages between indicators across trophic levels is similarly a prerequisite for tracking effects propagating through the food web, and, consequently, for indicator interpretation. Developing meaningful indicators under climate change calls for iterative indicator validations, accounting for natural processes such as trophic interactions and for trade-offs between management objectives, to enable learning as well as setting target levels or thresholds triggering actions in an adaptive manner. Such flexible strategies make a set of indicators operational over the long-term and facilitate success of EBM.
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| 7. |
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| 8. |
- Otto, Saskia A., et al.
(författare)
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A quantitative framework for selecting and validating food web indicators
- 2018
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Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X .- 1872-7034. ; 84, s. 619-631
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Tidskriftsartikel (refereegranskat)abstract
- Finding suitable state indicators is challenging and cumbersome in stochastic and complex ecological systems. Typically, a great focus is given to criteria such as data availability, scientific basis, or measurability. Features associated with the indicator's performance such as sensitivity or robustness are often neglected due to the lack of quantitative validation tools. In this paper, we present a simple but flexible framework for selecting and validating the performance of food web indicators. In specific, we suggest a 7-step process in which indicator performances at a regional scale are quantified and visualized allowing for the selection of complementary indicator suites. We demonstrate its application by comparing the performance of pelagic food web indicators for three basins of the Baltic Sea and by assessing the food web status based on selected indicator suites. Our analysis sheds light on spatial differences in indicator performances with respect to direct and indirect pressures, the role of non-linearity and non-additivity in pressure responses, as well as relationships between indicators caused by species interactions. Moreover, our results suggest that the present food web states in the Bornholm and Gotland basins of the Baltic Sea deviate distinctly from an earlier reference period. We advocate the use of our quantitative framework as decision-support tool for selecting suites of complementary indicators under given management schemes such as the EU Marine Strategy Framework Directive.
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| 9. |
- Otto, Saskia A., et al.
(författare)
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Ekosystembaserad utveckling av indikatorer för pelagiska födovävar
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Utveckling av indikatorer under EU:s ramdirektiv om en marin strategi, Havsmiljödirektivet, är en särskild utmaning när det gäller födovävar. Dessa indikatorer ska helst beskriva tillståndet i ett marint system, trots att sådana system är dynamiska och har komplexa interaktioner som ofta är icke-linjära. Havsområden som karaktäriseras av tydliga miljögradienter, som exempelvis Östersjön, medför ytterligare svårighet vid bedömningar av systemets tillstånd, eftersom det är nödvändigt att känna till hur pass relevanta indikatorerna är över hela spannet av miljöförhållanden som finns i området. Robusta tester och utvärderingar av indikatorerna är därför nödvändiga, särskilt för att undersöka hur de svarar på samtidiga påverkansvariabler och hur olika indikatorer är länkade genom artinteraktioner. I detta projekt använde vi flera olika metoder för att på ett robust sätt testa indikatorer för pelagiska födovävar i flera utsjöregioner i Östersjön: Bornholmsbassängen, Gotlandsbassängen, och Bottenhavet. Arbetet organiserades i tre delprojekt.I delprojekt 1 utvecklade vi ett modellbaserat ramverk där enskilda indikatorer testades mot enskilda påverkansvariabler, som till exempel koncentration av näringsämnen och fiskeintensitet. Detta möjliggjorde utvärdering av indikatorerna med avseende på deras sensitivitet, robusthet och specificitet. Med hjälp av ramverket kunde vi jämföra sex djurplanktonbaserade födovävsindikatorer och sju fiskbaserade födovävsindikatorer i två bassänger i Östersjön (Bornholmsbassängen och Gotlandsbassängen), medan i Bottenhavet jämfördes sex djurplanktonbaserade indikatorer (i detta område saknas längre tidsserier för fisk). De indikatorer som fick bäst resultat, inklusive de två tidigare föreslagna indikatorerna (’HELCOM core indicators’) baserade på djurplankton: Total djurplanktonförekomst (Total Zooplankton Abundance, TZA) och Medelstorlek av djurplankton (Mean Size, MS), analyserades vidare för att förstå eventuellt samspeloch påverkan mellan indikatorer.Två metoder för att testa indikatorer utvecklades för att kunna förstå och kvantifiera kopplingen mellan indikatorer orsakade av interaktioner (samspel) mellan olika arter, samt hur förhållandet mellan indikatorer och påverkansvariabler ser ut när hänsyns tas till indikatorernas koppling pga samspel mellan arter. Dessa metoder tillämpades sedan på olika typer av födovävsindikatorer på två samspelande nivåer i födoväven (delprojekt 2, storleksbaserade indikatorer samt mängd av fiskätande fisk och av bytesfiskar) och på tre samspelande nivåer (delprojekt 3, olika fisk och djurplanktonbaserade indikatorer) i Bornholmsbassängen och Gotlandsbassängen.Länkar mellan födovävsindikatorer från olika trofinivåer, som beror på de olika arternas samspel, var nödvändiga att ta hänsyn till för att kunna förklara hur dessa indikatorer varierade över tid. Detta visades i analyser av födovävsindikatorerna baserade på torsk Gadus morhua, en rovfisk, och i de indikatorer baserade på dess huvudsakliga bytesdjur skarpsill Sprattus sprattus och strömming Clupea harengus i Bornholmsbassängen, där både länkar (som motsvarar samspelet mellan rovdjur och byten) samt täthetsberoende effekter inom varje art behövde inkluderas för att förklara variationen i dessa pelagiska födovävsindikatorer från 1980-talet fram till 2012. Detta gällde för både abundans- och storleksbaserade indikatorer, men variationen över tid kunde förklaras bättre för de förstnämnda (testade 1979-2012) än de senare (testade 1984-2012). Vi lyckades inte anpassa någon statistiskt säkerställd modell för dessa två typer av indikatorer i Gotlandsbassängen, där mängden oförklarad variation förblev stor. När indikatorer testades på tre samspelande trofinivåer med en annan metod visade även dessa analyser att indikatorer på olika trofinivåer ofta påverkade varandra. Robusta modeller som förklarade variationen över tid kunde utvecklas för de djurplanktonbaserade indikatorerna (i båda bassängerna) och för indikatorn baserad på rovfisk (torsk) i Bornholmsbassängen. Utvecklingen över tid för storleksbaserade fiskindikatorerna förklarades sämre av modellerna än för de andra indikatorerna också i denna testmetod.Båda typerna av analyser i delprojekt 2 och 3 (två och tre samspelande nivåer i födoväven) visade att indikatorerna i allmänhet svarade mot ett flertal påverkansvariabler snarare än en enda, och att dessa var variabler kopplade till klimat, fiske och koncentration av näringsämnen eller primärproduktion. I studierna av två samspelande nivåer i födoväven, i detta fall de olika fiskbaserade indikatorerna, var salthalt, temperatur och syreförhållanden samt näringsämnen väsentliga för att kunna förklara utvecklingen av indikatorerna över tid. När tre samspelande nivåer i födoväven studerades – dvs. när djurplanktonbaserade indikatorer även var med i analysen – hade klimatvariabler ofta en starkare effekt på indikatorerna än fiske och primärproduktion. Detta belyser vikten av att ta hänsyn till klimatförändring när indikatorer tolkas och används till utvärdering av förvaltningsinsatser. Indikatorernas svar på externa påverkansvariabler var i många fall icke-linjära och berodde i vissa fall på nivån av en annan påverkansvariabel. Detta visar på nyttan med avancerade modellverktyg som kan fånga upp den relevanta dynamiken i system som karakteriseras av olika tillstånd (där olika orsakssamband kan gälla under olika tillstånd, s.k. ’alternativa regimer’).Projektets resultat utgör de första stegen mot en bedömning av födovävarnas nuvarande status, baserat på bassängspecifika uppsättningar av välfungerande fiskoch djurplanktonbaserade födovävsindikatorer. Våra resultat visar att (1) kopplingar mellan olika indikatorer, som uppkommer genom samspel mellan arter på olika nivåer i födoväven, bör beaktas i arbetet med att utveckla indikatorer för födovävar, (2) indikatorer för pelagiska födovävar som representerar djurplankton, planktonätande fisk och fiskätande fisk svarar alla mot flera samtidiga påverkansvariabler och (3) variationen över tid i variabler relaterade till fiske, övergödning (primärproduktion och näringsämnen) och klimatförändring förklarade indikatorernas historiska utveckling (1979/1984-2012).Det fanns ett fåtal skillnader mellan de olika metodernas resultat vad gäller de specifika sambanden mellan indikatorer och påverkansvariabler, men vi bedömer de samband som identifierats av minst två metoder som tillförlitliga. Dessa påverkansvariabler anses därför som de huvudsakliga. Det var dock inte alla indikatorer som hade statistiskt tillförlitliga samband till påverkansvariabler, varken inom en metod eller vid jämförelser mellan metoder. Därför är det ett urval av indikatorer som vi rekommenderar, givet det underliggande datamaterialet och provtagningsförfarandet.Vi rekommenderar att följande indikatorer används till riskanalyser eller utvärdering av förvaltningsalternativ för pelagiska födovävar i de studerade områdena, inom Havsmiljödirektivet:• För Bornholmsbassängen: Total djurplanktonförekomst (Total Zooplankton Abundance, TZA), förhållandet mellan hinnkräftor och hoppkräftor (Ratio Cladocerans to Copepods, RCC), skarpsill (Sprat), strömming (Herring), samt torsk (Cod).• För Gotlandsbassängen: Medelstorlek av djurplankton (Mean Size, MS), förhållandet mellan hinnkräftor och hoppkräftor (Ratio Cladocerans to Copepods, RCC), skarpsill (Sprat), strömming (Herring), samt torsk (Cod).• För Bottenhavet (där långsiktiga fiskdata saknas): Total djurplanktonförekomst (Total Zooplankton Abundance, TZA), Medelstorlek av djurplankton (Mean Size, MS) samt hoppkräftsbiomassa (Cops).
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| 10. |
- Otto, Saskia A., et al.
(författare)
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Habitat Heterogeneity Determines Climate Impact on Zooplankton Community Structure and Dynamics
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3, s. e90875-
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Tidskriftsartikel (refereegranskat)abstract
- Understanding and predicting species distribution in space and time and consequently community structure and dynamics is an important issue in ecology, and particularly in climate change research. A crucial factor determining the composition and dynamics of animal populations is habitat heterogeneity, i.e., the number of structural elements in a given locality. In the marine pelagic environment habitat heterogeneity is represented by the distribution of physical oceanographic parameters such as temperature, salinity and oxygen that are closely linked to atmospheric conditions. Little attention has been given, however, to the role of habitat heterogeneity in modulating the response of animal communities to external climate forcing. Here we investigate the long-term dynamics of Acartia spp., Temora longicornis, and Pseudocalanus acuspes, three dominant zooplankton species inhabiting different pelagic habitats in the Central Baltic Sea (CBS). We use the three copepods as indicator species for changes in the CBS zooplankton community and apply non-linear statistical modeling techniques to compare spatial population trends and to identify their drivers. We demonstrate that effects of climate variability and change depend strongly on species-specific habitat utilization, being more direct and pronounced at the upper water layer. We propose that the differential functional response to climate-related drivers in relation to strong habitat segregation is due to alterations of the species' environmental niches. We stress the importance of understanding how anticipated climate change will affect ecological niches and habitats in order to project spatio-temporal changes in species abundance and distribution.
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