| 1. |
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| 2. |
- 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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| 3. |
- Lind, Ulrika, et al.
(författare)
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Molecular Characterization of the alpha-Subunit of Na+/K+ ATPase from the Euryhaline Barnacle Balanus improvisus Reveals Multiple Genes and Differential Expression of Alternative Splice Variants
- 2013
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- The euryhaline bay barnacle Balanus improvisus has one of the broadest salinity tolerances of any barnacle species. It is able to complete its life cycle in salinities close to freshwater (3 PSU) up to fully marine conditions (35 PSU) and is regarded as one of few truly brackish-water species. Na+/K+ ATPase (NAK) has been shown to be important for osmoregulation when marine organisms are challenged by changing salinities, and we therefore cloned and examined the expression of different NAKs from B. improvisus. We found two main gene variants, NAK1 and NAK2, which were approximately 70% identical at the protein level. The NAK1 mRNA existed in a long and short variant with the encoded proteins differing only by 27 N-terminal amino acids. This N-terminal stretch was coded for by a separate exon, and the two variants of NAK1 mRNAs appeared to be created by alternative splicing. We furthermore showed that the two NAK1 isoforms were differentially expressed in different life stages and in various tissues of adult barnacle, i.e the long isoform was predominant in cyprids and in adult cirri. In barnacle cyprid larvae that were exposed to a combination of different salinities and pCO(2) levels, the expression of the long NAK1 mRNA increased relative to the short in low salinities. We suggest that the alternatively spliced long variant of the Nak1 protein might be of importance for osmoregulation in B. improvisus in low salinity conditions.
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| 4. |
- 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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| 5. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
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Larval connectivity and ecological coherence of marine protected areas (MPAs) in the Kattegat-Skagerrak region
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Marine protected areas (MPAs) are considered effective instrument to mitigate the loss of biodiversity in the sea. However, the management of MPA-networks is challenged by a lack of information of habitat distribution, and of how populations are connected between habitats and MPAs through dispersal of pelagic larval stages. In this study, the effect of larval connectivity on the ecological coherence of the MPA-networks in the Kattegat-Skagerrak area of the North Sea is investigated with special focus on the OSPAR-MPAs. By using biophysical models, the larval dispersal and connectivity of benthic organisms in the Kattegat-Skagerrak area is assessed. The report also aims to assess if a series of new model tools can be applied to identify optimal MPA-networks for benthic communities, and evaluate the existing MPA-networks with regards to larval connectivity. This report was prepared on request by the Swedish Agency for Water and Marine Management.
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| 6. |
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| 7. |
- Berglund, Moa, et al.
(författare)
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Optimal selection of marine protected areas based on connectivity and habitat quality
- 2012
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800. ; 240, s. 105-112
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Tidskriftsartikel (refereegranskat)abstract
- Networks of nature reserves and protected areas are important instruments to protect biodiversity, including harvested populations. Selection of marine protected networks (MPA) will depend on both the connectivity of concerned species and the habitat quality of individual sites. We explore the relative effect of connectivity and habitat quality on solutions for optimal networks of MPA using eigenvalue perturbation theory and a metapopulation model. Based on analyses of both synthetic networks and realistic connectivities for a sessile invertebrate with planktonic larvae in the Baltic Sea, we show that connectivity is expected to be more efficient than habitat quality as a selection criterion for MPA networks with realistic probabilities of local recruitment. In a second series of analyses we explore the effect of temporal variability of connectivity on the selection of optimal MPA networks. We show that optimal solutions of MPA networks converged when based on 8-10 years of connectivity information, corresponding to the time scale of the North-Atlantic oscillation. In conclusion, this study indicates that connectivity may be more important than habitat quality as selection criterion for MPAs when targeting species with long-distance dispersal that is typical for many marine invertebrates and fish. Our study also shows that connectivity patterns may be relatively consistent in time which suggests that the recent progress in biophysical modelling can offer a framework for optimal selection of MPA networks based on connectivities, which should improve guidelines for the design of functional MPA networks.
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| 8. |
- DeFaveri, J., et al.
(författare)
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HETEROGENEOUS GENOMIC DIFFERENTIATION IN MARINE THREESPINE STICKLEBACKS: ADAPTATION ALONG AN ENVIRONMENTAL GRADIENT
- 2013
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Ingår i: Evolution. - : Wiley. - 0014-3820. ; 67:9, s. 2530-2546
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Tidskriftsartikel (refereegranskat)abstract
- Evolutionary divergence among populations occupying ecologically distinct environments can occur even in the face of on-going gene flow. However, the genetic underpinnings, as well as the scale and magnitude at which this differentiation occurs in marine habitats are not well understood. We investigated the patterns and degree of genomic heterogeneity in threespine sticklebacks (Gasterosteus aculeatus) by assessing genetic variability in 20 nongenic and 20 genic (associated with genes important for freshwater adaptation) microsatellite loci in samples collected from 38 locations spanning the entire Baltic Sea coast to the North Sea boundary. Population divergence (F-ST approximate to 0.026) and structuring (five genetic clusters) was significantly more pronounced in the genic as compared to nongenic markers (F-ST approximate to 0.008; no genetic clusters). Patterns of divergence in the genic markers45% of which were identified as outlierscorrelated with local differences in salinity. Yet, a strong positive correlation between divergence in genic and nongenic markers, and their association with environmental factors suggests that adaptive divergence is reducing gene flow across the genome. Apart from providing a clear demonstration of heterogeneous genomic patterns of differentiation in a marine species, the results are indicative of adaptive population structuring across the relatively young Baltic Sea in spite of ample opportunities for gene flow.
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| 9. |
- Florin, Ann-Britt, et al.
(författare)
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Effects of a large northern European no-take zone on flatfish populations
- 2013
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 83:4, s. 939-962
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Tidskriftsartikel (refereegranskat)abstract
- In March 2006, a 360km(2) no-take zone (NTZ) was established north of Gotland in the central Baltic Sea, with the purpose to scientifically evaluate the effects of a fishing ban on flatfish populations. A monitoring programme was set up to study the populations in the NTZ and in a reference area east of Gotland where the fishing pressure was high. The programme included fishing with multimesh survey nets, modelling of potential larval export and estimation of fish consumption by large marine predators. Overall, the results showed a clear positive effect of the NTZ on turbot Scophthalmus maximus, with higher densities in the closed area compared with the fished area and also higher densities after closure compared with before. The NTZ also had older individuals and a more even sex ratio. This, in combination with a high potential for larval export from the NTZ to Gotland, shows that the marine reserve may be important for maintaining a viable S. maximus stock at Gotland. Also, for flounder Platichthys flesus, the densities were higher in the NTZ compared to the reference area and there was a net larval export to the fished area. For both species, density-dependent growth was evident, with a lower length at age in the closed area. Potential predation by grey seal Halichoerus grypus and great cormorant Phalacrocorax carbo sinesis on flatfishes, that could hamper the evaluation of the marine reserve, was also addressed. Taken together, the results show that there are clear benefits of the fishing ban for both flatfish species within the NTZ, while the net effects on fisheries are difficult to quantify.
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| 10. |
- Godhe, Anna, 1967, et al.
(författare)
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Seascape analysis reveals regional gene flow patterns among populations of a marine planktonic diatom
- 2013
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 280:1773
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the gene flow of the common marine diatom, Skeletonema marinoi, in Scandinavian waters and tested the null hypothesis of panmixia. Sediment samples were collected from the Danish Straits, Kattegat and Skagerrak. Individual strains were established from germinated resting stages. A total of 350 individuals were genotyped by eight microsatellite markers. Conventional F-statistics showed significant differentiation between the samples. We therefore investigated whether the genetic structure could be explained using genetic models based on isolation by distance (IBD) or by oceanographic connectivity. Patterns of oceanographic circulation are seasonally dependent and therefore we estimated how well local oceanographic connectivity explains gene flow month by month. We found no significant relationship between genetic differentiation and geographical distance. Instead, the genetic structure of this dominant marine primary producer is best explained by local oceanographic connectivity promoting gene flow in a primarily south to north direction throughout the year. Oceanographic data were consistent with the significant FST values between several pairs of samples. Because even a small amount of genetic exchange prevents the accumulation of genetic differences in F-statistics, we hypothesize that local retention at each sample site, possibly as resting stages, is an important component in explaining the observed genetic structure.
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