| 1. |
- Barth, Julia M.I., et al.
(författare)
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Genome architecture enables local adaptation of Atlantic cod despite high connectivity
- 2017
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 26:17, s. 4452-4466
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Tidskriftsartikel (refereegranskat)abstract
- Adaptation to local conditions is a fundamental process in evolution; however, mechanisms maintaining local adaptation despite high gene flow are still poorly understood. Marine ecosystems provide a wide array of diverse habitats that frequently promote ecological adaptation even in species characterized by strong levels of gene flow. As one example, populations of the marine fish Atlantic cod (Gadus morhua) are highly connected due to immense dispersal capabilities but nevertheless show local adaptation in several key traits. By combining population genomic analyses based on 12K single nucleotide polymorphisms with larval dispersal patterns inferred using a biophysical ocean model, we show that Atlantic cod individuals residing in sheltered estuarine habitats of Scandinavian fjords mainly belong to offshore oceanic populations with considerable connectivity between these diverse ecosystems. Nevertheless, we also find evidence for discrete fjord populations that are genetically differentiated from offshore populations, indicative of local adaptation, the degree of which appears to be influenced by connectivity. Analyses of the genomic architecture reveal a significant overrepresentation of a large ~5 Mb chromosomal rearrangement in fjord cod, previously proposed to comprise genes critical for the survival at low salinities. This suggests that despite considerable connectivity with offshore populations, local adaptation to fjord environments may be enabled by suppression of recombination in the rearranged region. Our study provides new insights into the potential of local adaptation in high gene flow species within fine geographical scales and highlights the importance of genome architecture in analyses of ecological adaptation.
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| 2. |
- Corell, Hanna, 1977-
(författare)
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Applications of ocean transport modelling
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The advective motion of seawater governs the transport of almost everything, animate or inanimate, present in the ocean and those lacking the ability to outswim the currents have to follow the flow. This makes modelling of advective ocean transports a powerful tool in various fields of science where a displacement of something over time is studied. The present thesis comprises four different applications of ocean-transport modelling, ranging from large-scale heat transports to the dispersion of juvenile marine organisms. The aim has been to adapt the method not only to the object of study, but also to the available model-data sets and in situ-observations. The first application in the thesis is a study of the oceanic heat transport. It illustrates the importance of wind forcing for not only the heat transport from the Indian to the Atlantic Ocean, but also for the net northward transport of heat in the Atlantic. In the next study focus is on the particle-transport differences between an open and a semi-enclosed coastal area on the Swedish coast of the Baltic Sea. The modelled patterns of sedimentation and residence times in the two basins are examined after particles having been released from a number of prescribed point sources. In the two final studies the transport-modelling framework is applied within a marine-ecology context and the transported entities are larvae of some Scandinavian sessile and sedentary species and non-commercial fishes (e.g. the bay barnacle, the blue mussel, the shore crab and the gobies). The effects of depth distribution of dispersing larvae on the efficiency of the Marine Protected Areas in the Baltic Sea are examined. Further, the diversity in dispersal and connectivity depending on vertical behaviour is modelled for regions with different tidal regimes in the North Sea, the Skagerrak and the Kattegat. The spatial scales dealt with in the studies varied from global to a highly resolved 182-metres grid. The model results, excepting those from the global study, are based on or compared with in situ-data.
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| 3. |
- Corell, Hanna, 1977, et al.
(författare)
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Depth distribution of larvae critically affects their dispersal and the efficiency of marine protected areas
- 2012
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 467, s. 29-46
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to improve estimates of dispersal by including information on larval traits, and in particular to explore how larval depth distribution affects connectivity and MPA (marine protected area) functionality in the Baltic Sea. A field survey showed that both invertebrates and fish differed in their larval depth distribution, ranging from surface waters to >100 m. A biophysical model of larval dispersal in the Baltic Sea showed that decreased depth distribution increased average dispersal distance 2.5-fold, decreased coastal retention and local recruitment, and substantially increased connectivity. Together with pelagic larval duration (PLD), depth distribution explained 80% of total variation in dispersal distance, whereas spawning season, and geographic and annual variations in circulation had only marginal effects. Median dispersal distances varied between 8 and 46 km, with 10% of simulated trajectories dispersing 30 to 160 km depending on drift depth and PLD. In the Baltic Sea, the majority of shallow Natura 2000 MPAs are <8 km in diameter. In the present study, only 1 of the 11 assessed larval taxa would have a recruitment >10% within MPAs of this size. Connectivity between MPAs was expected to be low for most larval trait combinations. Our simulations and the empirical data suggest that the MPA size within the Natura 2000 system is considerably below what is required for local recruitment of most sessile invertebrates and sedentary fish. Future designs of MPA networks would benefit from spatially explicit biophysical models that consider dispersal and connectivity for complex circulation patterns and informed larval traits.
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| 4. |
- Corell, Hanna, 1977, et al.
(författare)
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Difference in Particle Transport Between Two Coastal Areas in the Baltic Sea Investigated with High-Resolution Trajectory Modeling
- 2013
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Ingår i: Ambio. - Netherlands : Springer. - 0044-7447 .- 1654-7209. ; 42:4, s. SI 455-463
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Tidskriftsartikel (refereegranskat)abstract
- A particle-tracking model based on high-resolution ocean flow data was used to investigate particle residence times and spatial distribution of settling sediment for two geo-morphologically different Swedish coastal areas. The study was a part of a safety assessment for the location of a future nuclear-waste repository, and information about the particle-transport patterns can contribute to predictions of the fate of a possible leakage. It is also, to our knowledge, the first time particle-transport differences between two coastal areas have been quantified in this manner. In Forsmark, a funnel-shaped bay shielded by a number of islands, the average residence time for clay particles was 5 times longer than in the modeled part of Simpevarp, which is open to the Baltic Sea. In Forsmark, < 10 % of the released particles left the domain compared to 60-80 % in Simpevarp. These site-specific differences will increase over time with the differences in land uplift between the areas.
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| 5. |
- Corell, Hanna, 1977-, et al.
(författare)
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Larval depth distribution critically affects dispersal and the efficiency of marine protected areas
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Ingår i: Marine Ecology Progress Series. - 0171-8630 .- 1616-1599.
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to improve estimates of dispersal by including information on larval traits, and in particular to explore how larval depth distribution affects connectivity and MPA functionality in the Baltic Sea. A field survey showed that both invertebrates and fish differed in their larval depth distribution ranging from surface waters to more than 100 m. A biophysical model of larval dispersal in the Baltic Sea showed that decreased depthdistribution increased average dispersal distance 2.5 times, decreased coastal retention and local recruitment, and increased connectivity substantially. Together with pelagic larval duration (PLD), depth distribution explained 80% of total variation in dispersal distance, whereas spawning season, geographic and annual variations in circulation had only marginal effects. Median dispersal distances varied between 8 and 46 km, with 10% of simulated trajectories dispersing beyond 30-160 km depending on drift depth and PLD. In the Baltic Sea, the majority of shallow Natura 2000 MPAs are smaller than 8 km. In the present study, only one of the 11 assessed larval taxa would have a local recruitment >10% within MPAs of this size. Connectivity between MPAs was expected to be low for most larval trait combinations. Our simulations and the empirical data suggest that the MPA size within the Natura2000 system is considerably below what is required for local recruitment of most sessile invertebrates and sedentary fish. Future designs of MPA networks would benefit from spatially explicit biophysical models that consider dispersal and connectivity for complex circulation patterns and informed larval traits.
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| 6. |
- Corell, Hanna, 1977-, et al.
(författare)
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Wind sensitivity of the inter-ocean heat exchange
- 2009
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Ingår i: Tellus. Series A, Dynamic meteorology and oceanography. - : Stockholm University Press. - 0280-6495 .- 1600-0870. ; 61:5, s. 635-653
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Tidskriftsartikel (refereegranskat)abstract
- An idealised two-basin model is used to investigate the impact of the wind field on the heat exchange between the ocean basins. The scalar potential of the divergent component of the horizontal heat flux is computed, which gives a 'coarse-grained' image of the surface heat flux that captures the large-scale structure of the horizontal heat transport. Further the non-divergent component is examined, as well as the meridional heat transport and the temperature–latitude overturning stream function. A sensitivity analysis examines the heat transport response to changes in wind stress at different latitudes. The results are compared with results from an eddy-permitting global circulation model. The westerly wind stress over the Southern Ocean has two effects: a local reduction of the surface heat loss in response to the equatorward surface Ekman drift, and a global re-routing of the heat export from the Indo-Pacific. Without wind forcing, the Indo-Pacific heat export is released to the atmosphere in the Southern Ocean, and the net heat transport in the southern Atlantic is southward. With wind forcing, the Indo-Pacific export enters the Atlantic through the Aghulas and is released in the Northern Hemisphere. The easterlies enhance the poleward heat transport in both basins.
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| 7. |
- Jonsson, Per R., 1957, et al.
(författare)
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Recent decline in cod stocks in the North Sea - Skagerrak - Kattegat shifts the sources of larval supply
- 2016
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Ingår i: Fisheries Oceanography. - : Wiley. - 1054-6006 .- 1365-2419. ; 25:3, s. 210-228
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Tidskriftsartikel (refereegranskat)abstract
- Cod stocks in the North Sea, including the Kattegat and the Skagerrak, have declined dramatically since the 1970s. Occasionally there is a high recruitment of juveniles in Kattegat/Skagerrak, without leading to the rebuilding of adult cod stocks despite reduced fishing mortality. In a biophysical model of egg and larval drift, we examined the potential importance of extant and historical spawning grounds for recruitment of cod in the Kattegat/Skagerrak seas using data of spawning stock biomass from the 1970s and from today’s reduced stocks. The results suggest that Kattegat in the 1970s relied on largely locally retained (83%) larvae with little annual variation in recruitment. Kattegat also provided a substantial proportion of larvae recruiting in Swedish Skagerrak (72%). This is in contrast to pre-sent conditions where the Kattegat spawning stock has been reduced by 94%, and Kattegat only provides 34% of locally retained larvae and 30% to Swedish Skagerrak. Instead, the protected area in the Oresund and the Belt Sea are expected today to provide most larvae recruiting in Kattegat. Also, the inflow of larvae from the North Sea to Skagerrak and Kattegat can be significant although highly variable between years, with a positive correlation to the North-Atlantic Oscillation index (NAO). The rebuilding of healthy spawning areas in the Kattegat may be key for restoring local cod stocks in both Kattegat and along the Skagerrak coast. This poses a management challenge if cod with local ‘Kattegat’ adaptations, e.g., in terms of egg density and migration patterns, are lost or reduced to non-resilient densities.
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| 8. |
- Larsson, Josefine, et al.
(författare)
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Regional genetic differentiation in the blue mussel from the Baltic Sea area
- 2017
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Ingår i: Estuarine, Coastal and Shelf Science. - : Academic Press. - 0272-7714 .- 1096-0015. ; , s. 98-109
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Tidskriftsartikel (refereegranskat)abstract
- Connectivity plays an important role in shaping the genetic structure and in evolution of local adaptation. In the marine environment barriers to gene flow are in most cases caused by gradients in environmental factors, ocean circulation and/or larval behavior. Despite the long pelagic larval stages, with high potential for dispersal many marine organisms have been shown to have a fine scale genetic structuring. In this study, by using a combination of high-resolution genetic markers, species hybridization data and biophysical modeling we can present a comprehensive picture of the evolutionary landscape for a keystone species in the Baltic Sea, the blue mussel. We identified distinct genetic differentiation between the West Coast, Baltic Proper and Bothnian Sea regions, with lower gene diversity in the Bothnian Sea. Oceanographic connectivity together with salinity and to some extent species identity provides explanations for the genetic differentiation between the West Coast and the Baltic Sea (Baltic Proper and Bothnian Sea). The genetic differentiation between the Baltic Proper and Bothnian Sea cannot be directly explained by oceanographic connectivity, species identity or salinity, while the lower connectivity to the Bothnian Sea may explain the lower gene diversity. © 2016.
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| 9. |
- Moksnes, Per-Olav, et al.
(författare)
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Larval behavior and dispersal mechanisms in shore crab larvae : Local adaptations to different tidal environments?
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Recent studies indicate that local adaptations may occur in marine populations over relatively small geographic areas despite high dispersal potential if strong environmental gradients are present. Here we assess if local adaptations in larval behavior can develop in response to tidal gradients by studying the shore crab Carcinus maenas in the North Sea area using a combination of empirical and model studies. Specific aims of the study was to assess if shore crab larvae from different tidal environments have different swimming behaviors, and if these behaviors affect connectivity and recruitment success of the larvae. Field and laboratory studies demonstrated that newly hatched shore crab larvae from mesotidal Danish Wadden Sea displayed an inherited vertical migration rhythm with a circatidal periodicity, and that postlarvae swam in surface water almost exclusively during flood tides, suggesting that larvae use selective tidal stream transport to control the dispersal process. In contrast, shore crab larvae from microtidal Skagerrak displayed a nocturnal vertical migration behavior that switched to a diurnal behavior at the end of the larval phase, indicating an adaptation to avoid visual predators and to use wind-driven transport to reach shallow settlement areas. Results from a biophysical model showed that larval swimming behavior had a dominant role for the dispersal process and the recruitment success in the study area, and demonstrated that modeled tidal-migrating larvae in Wadden Sea had 2x higher recruitment success than larvae with a diel behavior. However, in microtidal Skagerrak no differences in recruitment success was found between the two larval behaviors. Lower fitness is suggested for tidal-migrating larvae in microtidal regions due to a predicted higher predation mortality. Consistent with recent population genetic studies, connectivity analyses indicated an oceanographic dispersal barrier in Eastern Wadden Sea that will restrict gene-flow between the two areas, and allow local adaptations in larval behavior.
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| 10. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
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Larval behavior and dispersal mechanisms in shore crab larvae: Local adaptations to different tidal environments?
- 2014
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590. ; 59:2, s. 588-602
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Tidskriftsartikel (refereegranskat)abstract
- Using a combination of empirical and model studies we tested whether European shore crab larvae (Carcinus maenas) from environments with different tidal regimes in the North Sea area have different swimming behaviors, and whether this affects connectivity and settlement success of larvae. Laboratory studies demonstrated the presence of an inherited tidal migration rhythm in newly hatched crab larvae from the mesotidal Danish Wadden Sea, and field studies showed that postlarvae swam in surface water almost exclusively during flood tides, suggesting that larvae use selective tidal stream transport to control the dispersal process. In contrast, shore crab larvae from microtidal Skagerrak displayed a nocturnal vertical migration behavior that appeared to switch to a diurnal behavior at the end of the postlarval phase, indicating an adaptation to avoid visual predators and to use wind-driven transport to reach shallow settlement areas. A biophysical model showed that tidal-migrating larvae in the Wadden Sea had two times higher settlement success than larvae with a diel behavior. However, no differences in settlement success were found between the two larval behaviors in microtidal Skagerrak, where lower fitness is suggested for tidal-migrating larvae due to higher predation mortality from visual predators. We suggest that the differences in inherited larval behavior in larvae from meso- and microtidal regions reflect local adaptations maintained through natural selection of successful recruits. Consistent with recent population genetic studies, modeled connectivity of shore crabs indicated an oceanographic dispersal barrier to gene flow in Eastern Wadden Sea that may facilitate such adaptations.
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| 11. |
- Rothausler, E., et al.
(författare)
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Abundance and dispersal trajectories of floating Fucus vesiculosus in the Northern Baltic Sea
- 2015
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Ingår i: Limnology and Oceanography. - : Wiley. - 1939-5590 .- 0024-3590. ; 60:6, s. 2173-2184
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Tidskriftsartikel (refereegranskat)abstract
- © 2015 Association for the Sciences of Limnology and Oceanography. Floating macroalgae play a fundamental role for the connectivity of littoral marine habitats. They can be found throughout the world’s oceans but information on their abundance and dispersal abilities is scarce. This information, however, is essential to evaluate their ecological role and the potential connectivity between populations of both the algae and associated biota. Here, we survey the abundance and spatiotemporal dispersal patterns of the floating brown alga Fucus vesiculosus in the Northern Baltic Sea. By incorporating a biophysical modeling approach, based on ocean circulation and surface winds, we demonstrate potential dispersal ranges, such as floating distances and directional trajectories of F. vesiculosus at different times of their reproductive season. Abundance of floating algae varied both spatially and temporally, with the highest densities being found during reproductive seasons. Evidenced by the fact that many algae were held back and accumulated in archipelagoes, the model suggests that a combination of local oceanographic features and seascapes strongly influences the dispersal of floating algae. However, a relatively high fraction of rafts spilled to more open sea areas, causing them to travel in multiple directions (e.g., Baltic Proper, Bothnian Bay, and Gulf of Finland) that are hundreds of kilometers away from their original sources, implying long-distance dispersal. We propose that the Northern Baltic Sea rocky littoral habitats are potentially well connected through abundant and long-reaching floating algae, with a chance to contribute to gene flow among F. vesiculosus populations.
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