| 1. |
- Heimbrand, Yvette, et al.
(författare)
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Cod otoliths document accelerating climate impacts in the Baltic Sea
- 2024
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Ingår i: Scientific Reports. - 2045-2322. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic deoxygenation of the Baltic Sea caused major declines in demersal and benthic habitat quality with consequent impacts on biodiversity and ecosystem services. Using Baltic cod otolith chemical proxies of hypoxia, salinity, and fish metabolic status and growth, we tracked changes from baseline conditions in the late Neolithic (4500 BP) and early twentieth century to the present, in order to understand how recent, accelerating climate change has affected this key species. Otolith hypoxia proxies (Mn:Mg) increased with expanding anoxic water volumes, but decreased with increasing salinity indexed by otolith Sr:Ca. Metabolic status proxied by otolith Mg:Ca and reconstructed growth were positively related to dissolved oxygen percent saturation, with particularly severe declines since 2010. This long-term record of otolith indicators provides further evidence of a profound state change in oxygen for the worse, in one of the world’s largest inland seas. Spreading hypoxia due to climate warming will likely impair fish populations globally and evidence can be tracked with otolith chemical biomarkers.
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| 2. |
- Hüssy, Karin, et al.
(författare)
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It’s elemental, my dear watson : Validating seasonal patterns in otolith chemical chronologies
- 2021
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 78:5, s. 551-566
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Tidskriftsartikel (refereegranskat)abstract
- Accurate age data are essential for reliable fish stock assessment. Yet many stocks suffer from inconsistencies in age interpretation. A new approach to obtain age makes use of the chemical composition of otoliths. This study validates the periodicity of recurrent patterns in25 Mg,31 P,34 K,55 Mn,63 Cu,64 Zn,66 Zn,85 Rb,88 Sr,138 Ba, and208 Pb in Baltic cod (Gadus morhua) otoliths from tag–recapture and known-age samples. Otolith P concentrations showed the highest consistency in seasonality over the years, with minima co-occurring with otolith winter zones in the known-age otoliths and in late winter – early spring when water temperatures are coldest in tagged cod . The timing of minima differs between stocks, occurring around February in western Baltic cod and 1 month later in eastern Baltic cod; seasonal maxima are also stock-specific, occurring in August and October, respectively. The amplitude in P is larger in faster-growing western compared with eastern Baltic cod. Seasonal patterns with minima in winter – late spring were also evident in Mg and Mn, but less consistent over time and fish size than P. Chronological patterns in P, and to a lesser extent Mg and Mn, may have the potential to supplement traditional age estimation or to guide the visual identification of translucent and opaque otolith patterns used in traditional age estimation.
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| 3. |
- Bergström, Lena, et al.
(författare)
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Klimatförändringar och biologisk mångfald : Slutsatser från IPCC och IPBES i ett svenskt perspektiv.
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- De stora miljö- och samhällsproblemen kommer inte ensamma. De är sammankopplade på olika sätt. Detta innebär utmaningar men ger också möjligheter att utveckla åtgärder och lösningar. Det gäller både för klimatfrågan och frågan om att motverka förlusten av biologisk mångfald och ekosystem. Kunskapens betydelse för att hantera dessa och andra aspekter är ovärderlig, såväl kring specifika frågeställningar som kring omständigheter och förutsättningar för åtgärdsarbetet.Den här kunskapssammanställningen har gjorts av forskare från Lunds universitet och Sveriges lantbruksuniversitet på uppdrag av Naturvårdsverket och SMHI. Forskarna har tagit avstamp i de omfattande kunskapsutvärderingar som gjorts av den mellanstatliga klimatpanelen (IPCC) och den mellanstatliga plattformen för biologisk mångfald (IPBES). Slutsatserna från IPCC och IPBES sätts i ett svenskt perspektiv, bland annat genom utvalda exempel vilka fungerar som aktuella illustrationer av hur klimatförändringar påverkar biologisk mångfald och ekosystem i Sverige.
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| 4. |
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| 5. |
- Breitburg, Denise, et al.
(författare)
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Declining oxygen in the global ocean and coastal waters
- 2018
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 359:6371
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Forskningsöversikt (refereegranskat)abstract
- Oxygen is fundamental to life. Not only is it essential for the survival of individual animals, but it regulates global cycles of major nutrients and carbon. The oxygen content of the open ocean and coastal waters has been declining for at least the past half-century, largely because of human activities that have increased global temperatures and nutrients discharged to coastal waters. These changes have accelerated consumption of oxygen by microbial respiration, reduced solubility of oxygen in water, and reduced the rate of oxygen resupply from the atmosphere to the ocean interior, with a wide range of biological and ecological consequences. Further research is needed to understand and predict long-term, global-and regional-scale oxygen changes and their effects on marine and estuarine fisheries and ecosystems.
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| 6. |
- Casini, Michele, et al.
(författare)
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Changes in population depth distribution and oxygen stratification are involved in the current low condition of the eastern Baltic Sea cod (Gadus morhua)
- 2021
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 18, s. 1321-1331
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Tidskriftsartikel (refereegranskat)abstract
- During the past 20 years, hypoxic areas have expanded rapidly in the Baltic Sea, which has become one of the largest marine "dead zones" in the world. At the same time, the most important commercial fish population of the region, the eastern Baltic cod, has experienced a drastic reduction in mean body condition, but the processes behind the relation between deoxygenation and condition remain elusive. Here we use extensive long-term monitoring data on cod biology and distribution as well as on hydrological variations to investigate the processes that relate deoxygenation and cod condition during the autumn season. Our results show that the depth distribution of cod has increased during the past 4 decades at the same time of the expansion, and shallowing, of waters with oxygen concentrations detrimental to cod performance. This has resulted in a progressively increasing spatial overlap between the cod population and low-oxygenated waters after the mid-1990s. This spatial overlap and the actual oxygen concentration experienced by cod therein statistically explained a large proportion of the changes in cod condition over the years. These results complement previous analyses on fish otolith microchemistry that also revealed that since the mid-1990s, cod individuals with low condition were exposed to low-oxygen waters during their life. This study helps to shed light on the processes that have led to a decline of the eastern Baltic cod body condition, which can aid the management of this population currently in distress. Further studies should focus on understanding why the cod population has moved to deeper waters in autumn and on analyzing the overlap with low-oxygen waters in other seasons to quantify the potential effects of the variations in physical properties on cod biology throughout the year.
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| 7. |
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| 8. |
- Deutsch, Lisa, 1965-
(författare)
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Global trade, food production and ecosystem support : Making the interactions visible
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modern food production is a complex, globalized system in which what we eat and how it is produced are increasingly disconnected. This thesis examines some of the ways in which global trade has changed the mix of inputs to food and feed, and how this affects food security and our perceptions of sustainability. One useful indicator of the ecological impact of trade in food and feed products is the Appropriated Ecosystem Areas (ArEAs), which estimates the terrestrial and aquatic areas needed to produce all the inputs to particular products.The method is introduced in Paper I and used to calculate and track changes in imported subsidies to Swedish agriculture over the period 1962-1994. In 1994, Swedish consumers needed agricultural areas outside their national borders to satisfy more than a third of their food consumption needs. The method is then applied to Swedish meat production in Paper II to show that the term “Made in Sweden” is often a misnomer. In 1999, almost 80% of manufactured feed for Swedish pigs, cattle and chickens was dependent on imported inputs, mainly from Europe, Southeast Asia and South America. Paper III examines ecosystem subsidies to intensive aquaculture in two nations: shrimp production in Thailand and salmon production in Norway. In both countries, aquaculture was shown to rely increasingly on imported subsidies. The rapid expansion of aquaculture turned these countries from fishmeal net exporters to fishmeal net importers, increasingly using inputs from the Southeastern Pacific Ocean.As the examined agricultural and aquacultural production systems became globalized, levels of dependence on other nations’ ecosystems, the number of external supply sources, and the distance to these sources steadily increased. Dependence on other nations is not problematic, as long as we are able to acknowledge these links and sustainably manage resources both at home and abroad. However, ecosystem subsidies are seldom recognized or made explicit in national policy or economic accounts. Economic systems are generally not designed to receive feedbacks when the status of remote ecosystems changes, much less to respond in an ecologically sensitive manner. Papers IV and V discuss the problem of “masking” of the true environmental costs of production for trade. One of our conclusions is that, while the ArEAs approach is a useful tool for illuminating environmentally-based subsidies in the policy arena, it does not reflect all of the costs. Current agricultural and aquacultural production methods have generated substantial increases in production levels, but if policy continues to support the focus on yield and production increases alone, taking the work of ecosystems for granted, vulnerability can result. Thus, a challenge is to develop a set of complementary tools that can be used in economic accounting at national and international scales that address ecosystem support and performance.We conclude that future resilience in food production systems will require more explicit links between consumers and the work of supporting ecosystems, locally and in other regions of the world, and that food security planning will require active management of the capacity of all involved ecosystems to sustain food production.
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| 9. |
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| 10. |
- Heimbrand, Yvette, et al.
(författare)
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Reading the biomineralized book of life: expanding otolith biogeochemical research and applications for fisheries and ecosystem-based management
- 2023
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Ingår i: Reviews in Fish Biology and Fisheries. - : Springer Science and Business Media LLC. - 0960-3166 .- 1573-5184. ; 33, s. 411-449
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Forskningsöversikt (refereegranskat)abstract
- Chemical analysis of calcified structures continues to flourish, as analytical and technological advances enable researchers to tap into trace elements and isotopes taken up in otoliths and other archival tissues at ever greater resolution. Increasingly, these tracers are applied to refine age estimation and interpretation, and to chronicle responses to environmental stressors, linking these to ecological, physiological, and life-history processes. Here, we review emerging approaches and innovative research directions in otolith chemistry, as well as in the chemistry of other archival tissues, outlining their value for fisheries and ecosystem-based management, turning the spotlight on areas where such biomarkers can support decision making. We summarise recent milestones and the challenges that lie ahead to using otoliths and archival tissues as biomarkers, grouped into seven, rapidly expanding and application-oriented research areas that apply chemical analysis in a variety of contexts, namely: (1) supporting fish age estimation; (2) evaluating environmental stress, ecophysiology and individual performance; (3) confirming seafood provenance; (4) resolving connectivity and movement pathways; (5) characterising food webs and trophic interactions; (6) reconstructing reproductive life histories; and (7) tracing stock enhancement efforts. Emerging research directions that apply hard part chemistry to combat seafood fraud, quantify past food webs, as well as to reconcile growth, movement, thermal, metabolic, stress and reproductive life-histories provide opportunities to examine how harvesting and global change impact fish health and fisheries productivity. Ultimately, improved appreciation of the many practical benefits of archival tissue chemistry to fisheries and ecosystem-based management will support their increased implementation into routine monitoring.[GRAPHICS].
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| 11. |
- Heimbrand, Yvette, et al.
(författare)
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Seeking the true time: Exploring otolith chemistry as an age-determination tool
- 2020
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 97, s. 552-565
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Tidskriftsartikel (refereegranskat)abstract
- Fish otoliths' chronometric properties make them useful for age and growth rate estimation in fisheries management. For the Eastern Baltic Sea cod stock (Gadus morhua), unclear seasonal growth zones in otoliths have resulted in unreliable age and growth information. Here, a new age estimation method based on seasonal patterns in trace elemental otolith incorporation was tested for the first time and compared with the traditional method of visually counting growth zones, using otoliths from the Baltic and North seas. Various trace elemental ratios, linked to fish metabolic activity (higher in summer) or external environment (migration to colder, deeper habitats with higher salinity in winter), were tested for age estimation based on assessing their seasonal variations in concentration. Mg:Ca and P:Ca, both proxies for growth and metabolic activity, showed greatest seasonality and therefore have the best potential to be used as chemical clocks. Otolith image readability was significantly lower in the Baltic than in the North Sea. The chemical (novel) method had an overall greater precision and percentage agreement among readers (11.2%, 74.0%) than the visual (traditional) method (23.1%, 51.0%). Visual readers generally selected more highly contrasting zones as annuli whereas the chemical readers identified brighter regions within the first two annuli and darker zones thereafter. Visual estimates produced significantly higher, more variable ages than did the chemical ones. Based on the analyses in our study, we suggest that otolith microchemistry is a promising alternative ageing method for fish populations difficult to age, such as the Eastern Baltic cod.
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| 12. |
- Jacobson, Philip, et al.
(författare)
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En fena på att bestämma ålens ursprung : ett pilotprojekt
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Samtliga ålar som sätts ut i svenska vatten är sedan 2009 kemiskt märkta med strontium. För att detektera strontiummärkningen utförs kemisk analys av ålens otoliter (hörselstenar), vilket kräver att ålen avlivas innan en analys är möjlig då otoliterna sitter i ålens huvud. Skulle det gå att ersätta otoliterna för att detektera strontiummärkningen med någon annan typ av vävnad som inte kräver att ålen avlivas?I detta pilotprojekt undersökte vi om det går att detektera strontiummärkningen i fenorna från strontiummärkta småålar. Vi preparerade och analyserade kemiska sammansättningen i otoliter, bröstfenor och stjärtfenor från 30 strontiummärkta småålar. Strontiummärkningen detekterades för samtliga småålar med deras otoliter men vi kunde inte detektera strontiummärkningen för någon individ med deras fenor.För ett stort antal fiskarter har fenprover framgångsrikt använts för att analysera skillnader i strontiumkoncentrationer för att kartlägga fiskens vandringar mellan vattenförekomster. Vi kunde inte detektera strontiummärkningen i ålens fenor denna pilotstudie vilket kan bero på strontium inte lagras in i ålens fenor på samma sätt som hos andra fiskar varför deras fenor inte kan ersätta otoliter för att detektera strontiummärkningen. Att vi inte kunde detektera strontiummärkningen kan också bero på att vi använde oss av för små ålar. För att säkerställa att ålens fenor inte kan ersätta dess otoliter skulle ytterligare kemiska analyser behöva utföras för att möjliggöra en jämförelse av strontiumkoncentrationen i fenorna mellan märkta och omärkta ålar av samma storlek och ålder för att säkerställa att fenorna inte kan ersätta ålens otoliter.Att arbeta och forska för att utveckla icke-dödliga insamlingsmetoder för att detektera strontiummärkningen hos utsatt ål är högst önskvärt då ålen klassas som akut hotad då dess populationsstorlek idag är 1-5 % av vad den var under perioden 1960-1979. Utveckling av icke-dödliga insamlingsmetoder skulle möjliggöra nya typer av utvärderingsstudier gällande ålutsättningar, exempelvis genom att jämföra vandringsbeteende mellan utsatt och naturligt rekryterad ål med exempelvis märkningsstudier som i regel kräver att ålens ursprung är känt innan märkningen sker.
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| 13. |
- Limburg, Karin
(författare)
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Diverse migration strategies of ariid catfishes along a salinity gradient in the Mekong River
- 2024
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Ingår i: Fisheries Research. - 0165-7836 .- 1872-6763. ; 279
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Tidskriftsartikel (refereegranskat)abstract
- Ariid catfishes (Ariidae family) are important migratory fish species in the Mekong River, with some species representing a major harvest component from the river. Limited biological information exists, and in particular their migration patterns are not well understood. This study examined life history strategies of three abundant ariid catfishes ( Cephalocassis borneensis, Arius maculatus, , and Osteogeneiosus militaris) ) in the Mekong River using otolith chemistry. Multiple trace elements in otolith sections were quantified using two analytical techniques: Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry and X-ray fluorescence microscopy. We found that 83 % of C. borneensis samples completed their life cycle exclusively in fresh water in the Mekong River, while 17 % samples of this species were occasionally found in higher salinity (brackish) waters. The two other species (A. A. maculatus and O. militaris) ) generally occupied higher salinity (estuary and coastal) areas, but demonstrated complex migratory patterns with up to three migration strategies observed (including both residents and migrants). With such complex migration strategies, management and conservation interventions are a challenge for these fish species.
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| 14. |
- Limburg, Karin E., et al.
(författare)
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In search of the dead zone : Use of otoliths for tracking fish exposure to hypoxia
- 2015
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Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963 .- 1879-1573. ; 141, s. 167-178
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Tidskriftsartikel (refereegranskat)abstract
- Otolith chemistry is often useful for tracking provenance of fishes, as well as examining migration histories. Whereas elements such as strontium and barium correlate well with salinity and temperature, experiments that examine manganese uptake as a function of these parameters have found no such correlation. Instead, dissolved manganese is available as a redox product, and as such, is indicative of low-oxygen conditions. Here we present evidence for that mechanism in a range of habitats from marine to freshwater, across species, and also present ancillary proxies that support the mechanism as well. For example, iodine is redox-sensitive and varies inversely with Mn; and sulfur stable isotope ratios provide evidence of anoxic sulfate reduction in some circumstances. Further, S may be incorporated trophically whereas other elements appear to be taken up directly from water. This research suggests a potential means to identify individual fish exposure to hypoxia, over entire lifetimes. With further testing and understanding, in the future fish may be able to be used as "mobile monitors" of hypoxic conditions. (C) 2014 The Authors. Published by Elsevier B.V.
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| 15. |
- Limburg, Karin E., et al.
(författare)
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Patterns and magnitude of Zn:Ca in otoliths support the recent phylogenetic typology of Salmoniformes and their sister groups
- 2010
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - 1205-7533. ; 67:4, s. 597-604
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Tidskriftsartikel (refereegranskat)abstract
- La chimie des otolithes de poissons sert a associer les poissons a des environnements specifiques. La chimie des otolithes peut aussi potentiellement servir d'outil dans la recherche phylogenetique, comme nous le demontrons ici chez les poissons salmonides et les taxons apparentes. Des cartes bidimensionnelles de la chimie de Zn:Ca dans les otolithes montrent des oscillations annuelles d'amplitude chez des membres des salmoniformes (les saumons se distinguant des coregones). Celles-ci se decelent aussi chez les esocides, mais pas de facon marquee chez les osmerides, ni chez les autres taxons moins apparentes. De plus, les amplitudes de Zn:Ca sont maximales chez les salmonides et diminuent chez les autres taxons : salmonides (saumons, ombres et coregones) > esocides > osmerides > autres. Une analyse spatiale sur des cartes en coupe sagittale de Zn:Ca les divise en cinq zones et fournit les moyennes de chaque zone ainsi que les moyennes totales. Une analyse des fonctions discriminantes des differentes zones d'otolithes separe encore mieux les groupes taxonomiques, mais montre que les brochets s'associent de plus pres aux salmonides et les osmerides au groupe externe. L'incorporation de Zn:Ca dans les otolithes peut etre un trait sous controle phylogenetique et la chimie de Zn:Ca des otolithes peut venir appuyer la reorganisation recente de la systematique des salmoniformes et de leurs groupes-soeurs.
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| 16. |
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| 17. |
- Limburg, Karin E., et al.
(författare)
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Tracking Baltic hypoxia and cod migration over millennia with natural tags
- 2011
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:22, s. E177-E182
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Tidskriftsartikel (refereegranskat)abstract
- Growing hypoxic and anoxic areas in coastal environments reduce fish habitat, but the interactions and impact on fish in these areas are poorly understood. Using natural tag properties of otoliths, we found significant correlations between the extent of Baltic Sea hypoxia and Mn/Ca ratios in regions of cod (Gadus morhua) otoliths corresponding to year 1 of life; this is associated with elevated bottom water dissolved manganese that increases with hypoxia. Elevated Mn/Ca ratios were also found in other years of life but with less frequency. We propose that cod exhibiting enhanced Mn/Ca ratios were exposed to dissolved manganese from hypoxia-induced redox dynamics in nursery areas. Neolithic (4500 B. P.) cod otoliths (n = 12) had lowlevels of Mn/Ca ratios, consistent with low hypoxia, but a single otolith dated to the younger Iron Age had a distinct growth band with an elevated Mn/Ca ratio. Sr/Ca patterns reflecting changes in environmental salinity and temperature were similar in both modern and Stone Age otoliths, indicating consistent migration habits across time, and Ba/Sr ratios in modern cod otoliths indicate increasing use of a more saline habitat with age. Using elemental ratios, numerous existing archival collections of otoliths could provide the means to reconstruct hypoxia exposure histories and major patterns of fish movement near dead zones globally.
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| 18. |
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| 19. |
- Limburg, Karin, et al.
(författare)
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Making the Otolith Magnesium Chemical Calendar-Clock Tick: Plausible Mechanism and Empirical Evidence
- 2018
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Ingår i: Reviews in Fisheries Science & Aquaculture. - : Informa UK Limited. - 2330-8249 .- 2330-8257. ; 26, s. 479-493
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Tidskriftsartikel (refereegranskat)abstract
- The incorporation of a number of readily measured trace elements into otoliths is considered to be under some sort of physiological control, but rarely are explicit mechanisms proposed. Studies of the incorporation of the trace element magnesium reveal that in some taxa there exists strong seasonal patterning, taking on the characteristics of a ''chemical calendar-clock.'' However, Mg/Ca and the isotopic ratio Mg-26/24 are less ''clock-like'' in taxa that are not as metabolically active. Herein, it is hypothesized that Mg uptake and incorporation are related to metabolic activity. Further, a two-step process of Mg incorporation is proposed: (1) limited entry into the otolith-bearing chamber through ion channels and (2) association with water-soluble proteins within the chamber. Supporting data from a range of taxa and life histories are provided; the authors' aim is to stimulate discussion and encourage physiologists to test these and alternative mechanistic hypotheses.
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| 20. |
- Limburg, Karin, et al.
(författare)
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Marked recent declines in boron in Baltic Sea cod otoliths – a bellwether of incipient acidification in a vast hypoxic system?
- 2023
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Ingår i: Biogeosciences. - 1726-4170 .- 1726-4189. ; 20, s. 4751–4760-
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification is spreading globally as a result of anthropogenic CO2 emissions, but the Baltic Sea has until recently been thought to be relatively well-buffered by terrigenous inputs of alkalinity from its watershed. We discovered a 3- to 5-fold decline in boron (as B : Ca) in otoliths of eastern Baltic cod (EBC) between the late 1990s and 2021. Examining a time series of EBC otoliths, we found varying levels of B : Ca starting in the 1980s, with the most recent years showing an all-time low for this period. This trend correlates with declines in pH and dissolved oxygen but not with changes in salinity. We examined possible physiological influences on B : Ca by including a collection of Icelandic cod as an “out-group”. Icelandic cod otoliths showed strongly positive correlations of B : Ca with physiologically regulated P : Ca; this was not the case for EBC. Finally, B : Ca in EBC otoliths is negatively correlated, to some extent, with Mn : Mg, a proposed proxy for hypoxia exposure. This negative relationship is hypothesized to reflect the dual phenomena of hypoxia and acidification as a result of decomposition of large algal blooms. Taken together, the otolith biomarkers Mn : Mg and B : Ca in cod suggest a general increase in both hypoxia and acidification within the Baltic intermediate and deep waters in the last decade.
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| 21. |
- Limburg, Karin
(författare)
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Ocean deoxygenation: a primer
- 2020
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Ingår i: One Earth. - : Elsevier BV. - 2590-3322. ; 2, s. 24-29
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Forskningsöversikt (populärvet., debatt m.m.)abstract
- Earth’s ocean is losing oxygen; since the mid-20th century, 1%–2% of the global ocean oxygen inventory has been lost, and over 700 coastal sites have reported new or worsening low-oxygen conditions. This “ocean deoxygenation” is increasing and of great concern because of the potential magnitude of adverse changes to both global and local marine ecosystems. Oxygen is fundamental for life and biogeochemical processes in the ocean. In coastal and shelf regions and semi-enclosed seas, over-fertilization of waters largely from agriculture, sewage, and airborne sources creates algal blooms that die and decay, consuming oxygen. Globally, climate warming both exacerbates the problems from eutrophication and reduces the introduction of oxygen to the interior of the ocean. We discuss mechanisms, scale, assessments, projections, and impacts, including impacts to human well-being, at the individual, community, and ecosystem levels. Deoxygenation together with other stressors presents a major environmental challenge to sustainability and human use of the ocean.
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| 22. |
- Limburg, Karin, et al.
(författare)
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Otolith chemistry indicates recent worsened Baltic cod condition is linked to hypoxia exposure
- 2019
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Deoxygenation worldwide is increasing in aquatic systems with implications for organisms' biology, communities and ecosystems. Eastern Baltic cod has experienced a strong decline in mean body condition (i.e. weight at a specific length) over the past 20 years with effects on the fishery relying on this resource. The decrease in cod condition has been tentatively linked in the literature to increased hypoxic areas potentially affecting habitat range, but also to benthic prey and/or cod physiology directly. To date, no studies have been performed to test these mechanisms. Using otolith trace element microchemistry and hypoxia-responding metrics based on manganese (Mn) and magnesium (Mg), we investigated the relationship between fish body condition at capture and exposure to hypoxia. Cod individuals collected after 2000 with low body condition had a higher level of Mn/Mg in the last year of life, indicating higher exposure to hypoxic waters than cod with high body condition. Moreover, lifetime exposure to hypoxia was even more strongly correlated to body condition, suggesting that condition may reflect long-term hypoxia status. These results were irrespective of fish age or sex. This implies that as Baltic cod visit poor-oxygen waters, perhaps searching for benthic food, they compromise their own performance. This study specifically sheds light on the mechanisms leading to the low condition of cod and generally points to the impact of deoxygenation on ecosystems and fisheries.
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| 23. |
- Limburg, Karin, et al.
(författare)
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Prehistoric vs. modern Baltic Sea cod fisheries : selectivity across the millennia
- 2008
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 275:1652, s. 2659-2665
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Tidskriftsartikel (refereegranskat)abstract
- Combining Stone Age and modern data provides unique insights for management, extending beyond contemporary problems and shifting baselines. Using fish chronometric parts, we compared demographic characteristics of exploited cod populations from the Neolithic Period (4500 BP) to the modern highly exploited fishery in the central Baltic Sea. We found that Neolithic cod were larger (mean 56.4 cm, 95% confidence interval (CI)±0.9) than modern fish (weighted mean length in catch =49.5±0.2 cm in 1995, 48.2±0.2 cm in 2003), and older (mean ages =4.7±0.11, 3.1±0.02 and 3.6±0.02 years for Neolithic, 1995, and 2003 fisheries, respectively). Fishery-independent surveys in 1995 and 2003 show that mean sizes in the stock are 16–17 cm smaller than reflected in the fishery, and mean ages approximately 1–1.5 years younger. Modelled von Bertalanffy growth and back-calculated lengths indicated that Neolithic cod grew to smaller asymptotic lengths, but were larger at younger ages, implying rapid early growth. Very small Neolithic cod were absent and large individuals were rare as in modern times. This could be owing to selective harvests, the absence of small and large fish in the area or a combination. Comparing modern and prehistoric times, fishery selection is evident, but apparently not as great as in the North Atlantic proper.
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| 24. |
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| 25. |
- Limburg, Karin, et al.
(författare)
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Trace Element Patterns in Otoliths: The Role of Biomineralization
- 2021
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Ingår i: Reviews in Fisheries Science & Aquaculture. - : Informa UK Limited. - 2330-8249 .- 2330-8257. ; 29, s. 445-477
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Forskningsöversikt (refereegranskat)abstract
- Otolith chemistry has gained increasing attention as a tool for analyzing various aspects of fish biology, such as stock dynamics, migration patterns, hypoxia and pollution exposure, and connectivity between habitats. While these studies often assume otolith elemental concentrations reflect environmental conditions, physiological processes are increasingly recognized as a modulating and/or controlling factor. In particular, biomineralization-the complex, enzyme-regulated construction of CaCO3 crystals scaffolded by proteins-is believed to play a critical role in governing otolith chemical patterns. This review aims to summarize the knowledge on otolith composition and biophysical drivers of biomineralization, present hypotheses on how biomineralization should affect element incorporation, and test the validity thereof with selected case studies. Tracers of environmental history are assumed to be dominated by elements that substitute for Ca during crystal growth or that occur randomly trapped within the crystal lattice. Strontium (Sr) and barium (Ba) largely comply with the biomineralization-based hypotheses that otolith element patterns reflect environmental concentrations, without additional effects of salinity, but can be influenced by physiological processes, typically exhibiting decreasing incorporation with increasing growth. Conversely, tracers of physiology are assumed to be elements under physiological control and primarily occur protein-bound in the otolith's organic matrix. Physiological tracers are hypothesized to reflect feeding rate and/or growth, decrease with fish age, and exhibit minimal influence of environmental concentration. The candidate elements phosphorus (P), copper (Cu) and zinc (Zn) confirm these hypotheses. Magnesium (Mg) is believed to be randomly trapped in the crystal structure and hence a candidate for environmental reconstruction, but the response to all examined drivers suggest Mg to be coupled to growth. Manganese (Mn) substitutes for Ca, but is also a co-factor in matrix proteins, and therefore exhibits otolith patterns reflecting both environmental (concentration and salinity) and physiological (ontogeny and growth) histories. A consistent temperature response was not evident across studies for either environmental or physiological tracers, presumably attributable to variable relationships between temperature and fish behavior and physiology (e.g., feeding rate, reproduction). Biomineralization thus has a controlling effect on otolith element concentrations for elements that are linked with somatic growth, but not for elements that substitute for Ca in the crystal lattice. Interpretation of the ecological significance of patterns from field samples therefore needs to consider the impact of the underlying biomineralization processes of the element in question as well as physiological processes regulating the availability of ions for inclusion in the growing crystal lattice. Such understanding will enhance the utility of this technique to address fisheries management questions.
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| 26. |
- Limburg, Karin
(författare)
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Tracking Fish Lifetime Exposure to Mercury Using Eye Lenses
- 2023
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Ingår i: Environmental Science and Technology Letters. - : American Chemical Society (ACS). - 2328-8930. ; 10, s. 222-227
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Tidskriftsartikel (refereegranskat)abstract
- Mercury (Hg) uptake in fish is affected by diet, growth, and environmental factors such as primary productivity or oxygen regimes. Traditionally, fish Hg exposure is assessed using muscle tissue or whole fish, reflecting both loss and uptake processes that result in Hg bioaccumulation over entire lifetimes. Tracking changes in Hg exposure of an individual fish chronologically throughout its lifetime can provide novel insights into the processes that affect Hg bioaccumulation. Here we use eye lenses to determine Hg uptake at an annual scale for individual fish. We assess the widely distributed benthic round goby (Neogobius melanostomus) from the Baltic Sea, Lake Erie, and the St. Lawrence River. We aged layers of the eye lens using proportional relationships between otolith length at age and eye lens radius for each individual fish. Mercury concentrations were quantified using laser ablation inductively coupled plasma mass spectrometry. The eye lens Hg content revealed that Hg exposure increased with age in Lake Erie and the Baltic Sea but decreased with age in the St. Lawrence River, a trend not detected using muscle tissues. This novel methodology for measuring Hg concentration over time with eye lens chronology holds promise for quantifying how global change processes like increasing hypoxia affect the exposure of fish to Hg.
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| 27. |
- Olson, Carina, 1949-
(författare)
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Neolithic Fisheries : Osteoarchaeology of Fish Remains in the Baltic Sea Region
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The variety of fish species found at the archaeological sites indicates the exploitation of local and regional ecosystems. The focus of the fisheries varies from site to site. The study is based on the analyses of faunal materials from 10 archaeological sites from Eastern Middle Sweden, Gotland, and Åland dating to approximately 3800 – 1850 B.C. The mainland assemblages are mainly burnt and highly fragmented. When comparing burnt and unburnt bone materials, results showed a marked predominance of fish specimens within the unburnt assemblages. The burnt bone materials showed a striking preponderance of marine mammals. The burning process impairs identification and quantification of fishbone. Species presence per context complemented summary data and showed that low and medium frequency species were handled more often than summary data indicate. Intra-site studies of burnt bones demonstrated the importance of detailed studies of the taphonomic history of the faunal assemblages. At Ajvide on the island of Gotland, large amounts of well preserved unburnt faunal remains, and ca. 600 bone fishhooks have been unearthed. Replicas of fishhooks from this assemblage were subjected to strength test, osteometric, morphological, and breakage studies. Results point to an elaborated fishing technology for capturing medium sized cod. Incremental studies of cod otoliths (ear stones) from Ajvide showed that most cod were captured in fall and winter. A comparison with the contemporaneous Jettböle site on the Åland islands, showed that in general smaller cod and herring were captured there. The ecological conditions were somewhat different during the Neolithic. The growth pattern for cod indicate a more rapid growth for young cod but with a lower asymptotic length compared to modern cod.
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| 28. |
- Olson, Carina, et al.
(författare)
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Stone Age fishhooks - how were they dimensioned? : Morphology, strength test, and breakage pattern fo Neolithic bone fishhooks from Ajvide, Gotland, Sweden
- 2008
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Ingår i: Journal of Archaeological Science. - : Elsevier BV. - 0305-4403 .- 1095-9238. ; 35:10, s. 2813-2823
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Tidskriftsartikel (refereegranskat)abstract
- The late Stone Age Pitted Ware site at Ajvide, Gotland, in the Baltic Sea, Sweden, has revealed a large deposit of fishbone and approximately 400 bone fishhooks, complete and incomplete. Cod (Gadus morhua), which is one of the most abundant fish species in the bone assemblage, was probably caught with hook and line fishing. To investigate the fishhooks' field of application, a morphological and morphometric study was performed on 384 available hooks. Two sets of replicas made Of four selected Original fishhooks were submitted to a strength test. A breakage study of the incomplete hooks in comparison with the strength-tested hooks was carried out in order to distinguish fresh breaks from dry breaks. It seems that a certain morphology for fishhooks was preferred at Ajvide, indicating they were produced by skilled craftsmen for special usage. The strength test showed that the hooks had a weight bearing capacity more than the average size of cod caught at Ajvide. Using results of these tests, we predicted that the mean breaking Strength of 46 intact Ajvide hooks was 96.6 +/- 26.1 (s.d.) Newtons (equivalent to 9.85 +/- 2.7 kg). The design of fishhooks changed somewhat over time, being slightly larger in the oldest layers of the site. The breakage patterns of the hooks show that the bow was the most common area of breakage. The design and weight bearing capacity of the hooks point to a specialized cod fishery from boats in deep water.
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| 29. |
- Orio, Alessandro, et al.
(författare)
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Deoxygenation impacts on Baltic Sea cod: Dramatic declines in ecosystem services of an iconic keystone predator
- 2022
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Ingår i: AMBIO: A Journal of the Human Environment. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 51, s. 626-637
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Tidskriftsartikel (refereegranskat)abstract
- The intensified expansion of the Baltic Sea's hypoxic zone has been proposed as one reason for the current poor status of cod (Gadus morhua) in the Baltic Sea, with repercussions throughout the food web and on ecosystem services. We examined the links between increased hypoxic areas and the decline in maximum length of Baltic cod, a demographic proxy for services generation. We analysed the effect of different predictors on maximum length of Baltic cod during 1978-2014 using a generalized additive model. The extent of minimally suitable areas for cod (oxygen concentration >= 1 ml l(-1)) is the most important predictor of decreased cod maximum length. We also show, with simulations, the potential for Baltic cod to increase its maximum length if hypoxic areal extent is reduced to levels comparable to the beginning of the 1990s. We discuss our findings in relation to ecosystem services affected by the decrease of cod maximum length.
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| 30. |
- Samson, Melvin A., et al.
(författare)
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Discrimination potential of otolith chemistry to distinguish two parapatric species of flounder (Platichthys) in the Baltic Sea
- 2022
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Ingår i: Journal of Sea Research. - : Elsevier. - 1385-1101 .- 1873-1414. ; 186
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Tidskriftsartikel (refereegranskat)abstract
- Baltic Sea flounder were recently split into two species, the offshore spawner Platichthys flesus and coastal spawner Platichthys solemdali. The two species can only be distinguished based on egg and sperm characteristics and via genetic analyses, which limits the species identification methods of larvae and juveniles to molecular techniques. We investigated whether otolith chemistry could be used as an additional tool to identify flounder to species level. We tested for species-specific differences in otolith multi-elemental signatures and spatial consistency of those differences for the early life stages of flounder in three areas of the central Baltic Sea (ICES SD 24-28), where the distribution of both species overlaps. Otolith chemistry signatures obtained through maternal transfer (i.e. core chemistry) and signatures that reflect the post-hatching phase were not significantly different between species. Species-specific differences at the sub-regional scale were only found for the Latvian coastal survey area for multiple elements (Ba, Cu, Mg, Pb, Sr and Zn), but were insufficiently distinct for reliable species discrimination. Geographic classification of age-0 juveniles to survey area was more successful than classification to species, which was reflected by a spatial trend in otolith Sr:Ca that followed the salinity gradient and higher Mn:Ca and I:Ca for Latvian individuals. Otolith chemistry of early life flounder from the Baltic Sea reflects spatial variability in environmental conditions but does not differentiate between the two flounder species in sympatric habitats.
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| 31. |
- Sumaila, U. Rashid, et al.
(författare)
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WTO must ban harmful fisheries subsidies
- 2021
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 374:6567, s. 544-544
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 32. |
- Westin, Lars, et al.
(författare)
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Newly discovered reproductive isolation reveals sympatric populations of Esox lucius in the Baltic
- 2002
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Ingår i: Journal of Fish Biology. - London : Academic Press. - 0022-1112 .- 1095-8649. ; 61:6, s. 1647-1652
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Tidskriftsartikel (refereegranskat)abstract
- Two populations of pike Esox lucius have been identified on the eastern coast of Sweden, in the Baltic Sea. These live together, but separate into two different populations during the spawning season. One is an obligate freshwater spawner and the other not only reproduces in ambient Baltic salinities, but appears not to enter fresh water at all.
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