| 1. |
- Barth, Julia M.I., et al.
(författare)
-
Genome architecture enables local adaptation of Atlantic cod despite high connectivity
- 2017
-
Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 26:17, s. 4452-4466
-
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.
|
|
| 2. |
- Corell, Hanna, 1977, et al.
(författare)
-
Depth distribution of larvae critically affects their dispersal and the efficiency of marine protected areas
- 2012
-
Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 467, s. 29-46
-
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.
|
|
| 3. |
- Eriander, Louise, 1984, et al.
(författare)
-
The effects of small-scale coastal development on the eelgrass (Zostera marina L.) distribution along the Swedish west coast – Ecological impact and legal challenges
- 2017
-
Ingår i: Ocean and Coastal Management. - : Elsevier BV. - 0964-5691. ; 148, s. 182-194
-
Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic impacts on coastal areas have led to an increased degradation of marine environments globally. Eelgrass ecosystems are particularly susceptible to human induced stressors as they are sensitive to low light conditions and usually grow in shallow protected areas where pressure from coastal development is high. The extensive decline in coverage of eelgrass along the Swedish Northwest coast since the 1980s has largely been attributed to the effects of coastal eutrophication and overfishing. However, the impact on eelgrass from small-scale coastal development (docks and marinas) has never been investigated in this area. The aim of this study was to assess the local and large-scale effect of shading by docks and marinas on eelgrass habitats along the Swedish NW coast and to investigate the decision process behind small-scale exploitation to identify problems with the current legislation, which allows for continued exploitation of eelgrass. Through field assessments of eelgrass around docks and analysis of available data on eelgrass and dock distribution along the coast, the present study demonstrates that shading from docks reduced eelgrass coverage with on average 42e64% under and adjacent to the docks, and that floating docks affected larger areas and caused a much stronger reduction in eelgrass coverage (up to 100% loss) compared to docks elevated on poles (up to 70% reduction in coverage). The total eelgrass area negatively affected by docks and marinas along the NW coast was estimated to approximately 480 ha, an area corresponding to over 7% of the present areal coverage of eelgrass in the region. The analysis of decisions for dock construction showed that eelgrass was generally not assessed or considered in the decision process and that 69e88% of the applications were approved also in areas where eelgrass was present. Furthermore, marine protected areas only marginally reduced the approval of applications in eelgrass habitats. The continued small-scale development along the Swedish NW coast constitutes a significant threat to the already decimated coverage of eelgrass along the coast and changes in the management practices are needed in order to achieve both national and international goals on environmental status.
|
|
| 4. |
- Jahnke, Marlene, et al.
(författare)
-
Integrating genetics, biophysical, and demographic insights identifies critical sites for seagrass conservation
- 2020
-
Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 30:6
-
Tidskriftsartikel (refereegranskat)abstract
- The eelgrass Zostera marina is an important foundation species of coastal areas in the Northern Hemisphere, but is continuing to decline, despite management actions. The development of new management tools is therefore urgent in order to prioritize limited resources for protecting meadows most vulnerable to local extinctions and identifying most valuable present and historic meadows to protect and restore, respectively. We assessed 377 eelgrass meadows along the complex coastlines of two fjord regions on the Swedish west coast-one is currently healthy and the other is substantially degraded. Shoot dispersal for all meadows was assessed with Lagrangian biophysical modeling (scale: 100-1,000 m) and used for barrier analysis and clustering; a subset (n = 22) was also assessed with population genetic methods (20 microsatellites) including diversity, structure, and network connectivity. Both approaches were in very good agreement, resulting in seven subpopulation groupings or management units (MUs). The MUs correspond to a spatial scale appropriate for coastal management of "waterbodies" used in the European Water Framework Directive. Adding demographic modeling based on the genetic and biophysical data as a third approach, we are able to assess past, present, and future metapopulation dynamics to identify especially vulnerable and valuable meadows. In a further application, we show how the biophysical approach, using eigenvalue perturbation theory (EPT) and distribution records from the 1980s, can be used to identify lost meadows where restoration would best benefit the present metapopulation. The combination of methods, presented here as a toolbox, allows the assessment of different temporal and spatial scales at the same time, as well as ranking of specific meadows according to key genetic, demographic and ecological metrics. It could be applied to any species or region, and we exemplify its versatility as a management guide for eelgrass along the Swedish west coast.
|
|
| 5. |
- Jahnke, Marlene, et al.
(författare)
-
Seascape genetics and biophysical connectivity modelling support conservation of the seagrass Zostera marina in the Skagerrak-Kattegat region of the eastern North Sea
- 2018
-
Ingår i: Evolutionary Applications. - : Wiley. - 1752-4563 .- 1752-4571. ; 11:5, s. 645-661
-
Tidskriftsartikel (refereegranskat)abstract
- Maintaining and enabling evolutionary processes within meta-populations are critical to resistance, resilience and adaptive potential. Knowledge about which populations act as sources or sinks, and the direction of gene flow, can help to focus conservation efforts more effectively and forecast how populations might respond to future anthropogenic and environmental pressures. As a foundation species and habitat provider, Zostera marina (eelgrass) is of critical importance to ecosystem functions including fisheries. Here, we estimate connectivity of Z.marina in the Skagerrak-Kattegat region of the North Sea based on genetic and biophysical modelling. Genetic diversity, population structure and migration were analysed at 23 locations using 20 microsatellite loci and a suite of analytical approaches. Oceanographic connectivity was analysed using Lagrangian dispersal simulations based on contemporary and historical distribution data dating back to the late 19th century. Population clusters, barriers and networks of connectivity were found to be very similar based on either genetic or oceanographic analyses. A single-generation model of dispersal was not realistic, whereas multigeneration models that integrate stepping-stone dispersal and extant and historic distribution data were able to capture and model genetic connectivity patterns well. Passive rafting of flowering shoots along oceanographic currents is the main driver of gene flow at this spatial-temporal scale, and extant genetic connectivity strongly reflects the ghost of dispersal past sensu Benzie, . The identification of distinct clusters, connectivity hotspots and areas where connectivity has become limited over the last century is critical information for spatial management, conservation and restoration of eelgrass.
|
|
| 6. |
- Jahnke, Marlene, et al.
(författare)
-
Seascape genomics identify adaptive barriers correlated to tidal amplitude in the shore crab Carcinus maenas
- 2022
-
Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 31:7, s. 1980-94
-
Tidskriftsartikel (refereegranskat)abstract
- Most marine invertebrates disperse during a planktonic larval stage that may drift for weeks with ocean currents. A challenge for larvae of coastal species is to return to coastal nursery habitats. Shore crab (Carcinus maenas L.) larvae are known to show tidal rhythmicity in vertical migration in tidal areas and circadian rhythmicity in micro-tidal areas, which seems to increase successful coastal settlement. We studied genome-wide differentiation based on 24,000 SNPs of 12 native populations of shore crab sampled from a large tidal amplitude gradient from macro-tidal (ca. 8 m) to micro-tidal (ca. 0.2 m). Dispersal and recruitment success of larvae was assessed with a Lagrangian biophysical model, which showed a strong effect of larval behavior on long-term connectivity, and dispersal barriers that partly coincided with different tidal environments. The genetic population structure showed a subdivision of the samples into three clusters, which represent micro-, meso- and macro-tidal areas. The genetic differentiation was mostly driven by 0.5% outlier loci, which showed strong allelic clines located at the limits between the three tidal areas. Demographic modelling suggested that the two genetic barriers have different origins. Differential gene expression of two clock genes (cyc and pdp1) further highlighted phenotypic differences among genetic clusters that are potentially linked to the differences in larval behaviour. Taken together, our seascape genomic study suggest that tidal regime acts as a strong selection force on shore crab population structure, consistent with larval behaviour affecting dispersal and recruitment success.
|
|
| 7. |
- Jephson, Therese, et al.
(författare)
-
Trophic interactions in Zostera marina beds along the Swedish coast
- 2008
-
Ingår i: Marine Ecology - Progress Series. - : Inter-Research Science Center. - 1616-1599 .- 0171-8630. ; 369, s. 63-76
-
Tidskriftsartikel (refereegranskat)abstract
- We compared eelgrass Zostera marina communities in 3 regions in Sweden believed to be affected by eutrophication and overfishing, to determine whether bottom-up or top-down processes control the biomass of epiphytic macroalgae and grazers. Nitrogen and carbon isotope signatures were analyzed to explore the food webs and to identify the grazing species feeding on filamentous algae and/or eelgrass. Mixing model (IsoSource version 1.3.1) analysis of the isotope signatures indicated that the amphipods Gammarus locusta and Microdeutopus gryllotalpa fed primarily on filamentous algae and that only 2 small gastropod species consumed eelgrass. Moreover, the grass shrimp Palaemon elegans and F adspersus were ca. 1 trophic level above amphipods and algae, but according to the mixing model played different trophic roles in the different areas. The highest biomass of filamentous algae was found in the west coast beds housing grazers with the lowest biomass and mean size (predominantly G. locusta and M. gryllotalpa, 0.5 to 3 mm). In contrast, the Baltic Sea beds had low algal biomass, but the grazers (mostly G. locusta and Idotea baltica) had higher biomass and were significantly larger (mean size ca. 10 mm). An overall negative correlation was found between grazer biomass and biomass of filamentous algae. The significantly smaller grazers and absence of isopod grazers on the west coast may be due to substantial consumption by small predatory fish. This supports the suggestions that, in Swedish eelgrass beds, grazers are top-down controlled, and overexploitation. of large predators and eutrophication play an important role in the recent increases in algal biomass.
|
|
| 8. |
|
|
| 9. |
- Jonsson, Per R., 1957, et al.
(författare)
-
How to select networks of marine protected areas for multiple species with different dispersal strategies
- 2016
-
Ingår i: Diversity and Distributions: A journal of biological invasions and biodiversity. - : Wiley. - 1366-9516 .- 1472-4642. ; 22:2, s. 161-173
-
Tidskriftsartikel (refereegranskat)abstract
- Aim To develop and test theory based on connectivity to identify optimal networks of marine protected areas (MPAs) that protect multiple species with a range of dispersal strategies. Location The eastern North Sea in the Atlantic Ocean. Methods Theory of finding optimal MPA network is based on eigenvalue perturbation theory applied to population connectivity. Previous theory is here extended to the persistence of multiple species by solving a maximization problem with constraints, which identifies an optimal consensus network of MPAs. The theory is applied to two test cases within a 120,000km2 area in the North Sea where connectivity was estimated with a biophysical model. In a realistic case, the theory is applied to the protection of rocky-reef habitats, where the biophysical model is parameterized with realistic dispersal traits for key species. Theoretical predictions of optimal networks were validated with a simple metapopulation model. Persistence of optimal consensus MPA networks is compared to randomly selected networks as well as to the existing MPA network. Results Despite few overlapping MPA sites for the optimal networks based on single dispersal strategies, the consensus network for multiple dispersal strategies performed well for 3 of 4 contrasting strategies even without user-defined constraints. In the test with five realistic dispersal strategies, representing a community on threatened rocky reefs, the consensus network performed equally well compared to solutions for single species. Different dispersal strategies were also protected jointly across the MPA network (93% of sites), in contrast to simulations of the existing MPA network (2% of sites). Consensus networks based on connectivity were significantly more efficient compared to existing MPAs. Main conclusions Our findings suggest that the new theoretic framework can identify a consensus MPA network that protects a whole community containing species with multiple dispersal strategies.
|
|
| 10. |
- Jonsson, Per R., 1957, et al.
(författare)
-
Recent decline in cod stocks in the North Sea - Skagerrak - Kattegat shifts the sources of larval supply
- 2016
-
Ingår i: Fisheries Oceanography. - : Wiley. - 1054-6006 .- 1365-2419. ; 25:3, s. 210-228
-
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.
|
|
| 11. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
-
Identifying new areas adding larval connectivity to existing networks of MPAs : The case of Kattegat and Skagerrak
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Networks of marine protected areas (MPAs) are presently being developed in many countries with the aim to preserve biodiversity and restore overexploited stocks. However, one major challenge for the design and management of a functional MPA-network is the lack of information about how larval dispersal affects connectivity in the network and persistence of included species. Tools have been lacking that include larval connectivity into design and assessment of MPA-network, and in particular regarding finding the best new areas that will enhance larval connectivity in the existing networks. In the present study we build on earlier model studies on larval dispersal and assessment of MPA-networks in the Kattegat-Skagerrak area (Moksnes et al. 2014), and use novel theoretical tools to identify new areas for the existing MPA-network in the Skagerrak-Kattegat-Danish Strait area that would best enhance larval connectivity for benthic communities living shallower than 100 m. We also use new methods to identify areas with restricted larval dispersal and subpopulations within the study area, to assist in the selection of new MPAs. The assessment includes also benthic communities that are intolerant to low salinities and therefore have limited distribution in the Baltic Sea. The study demonstrates that the connectivity and protection of benthic communities in the existing MPA-network could be substantially improved by a relatively small addition of carefully selected new MPAs. Adding approximately 1000 km2 of model-selected areas to the existing network (representing an extension of the existing network area with 15–19 %) increased the simulated populations of benthic organism with on average 39–103 % in comparison with the existing network. In contrast, a random selection of new MPAs of the same size only increased the population sizes with 0–19 %. The study identified several areas with restricted larval dispersal and isolated subpopulations within the study area, which may have important implications for management of both genetic and species diversity. The results suggest that it may be important to manage the western Baltic Sea, Kattegat, coastal Skagerrak (including both the Swedish and Norwegian coasts) and the area northwest of Jutland as separate management units since restricted larval dispersal may create genetically distinct subpopulations in these regions. The study also identified restricted larval dispersal within Kattegat and Skagerrak that may create areas with benthic communities that are demographically isolated from neighboring communities. For management of populations and local species diversity, it is important to ensure that there are MPAs within each demographically isolated area. One such area was identified along the Swedish Kattegat coast, which presently has few large MPAs, in particular for shallow benthic communities (<20 m). The analysis identified shallow areas within the larger bays Skälderviken and the Laholmsbukten, and a deeper area located between the Laholmsbukten and Stora Middelgrund in southeastern Kattegatt as being key areas for larval connectivity and persistence of shallow and deep benthic communities, respectively, in Kattegat. The results suggest that these areas (covering approximately 700 km2 in total) constitute the best additions, in respect of larval connectivity, to the existing MPA-network found within Swedish waters. For management purposes, these results should only be viewed as guide for identifying general areas within the study region that are important for improving the connectivity of pelagic larvae within the existing MPA-network. Due to the limitation of the model they should not be viewed as a blue-print of the exact locations of an optimal extension, particularly not in the coastal zone. However, the study does represent the best available assessment to day of larval dispersal and connectivity in the study area, and the result could therefore provide manager with helpful information of one important aspect to include in the decision process when selecting new MPAs.
|
|
| 12. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
-
Larval behavior and dispersal mechanisms in shore crab larvae: Local adaptations to different tidal environments?
- 2014
-
Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590. ; 59:2, s. 588-602
-
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.
|
|
| 13. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
-
Larval connectivity and ecological coherence of marine protected areas (MPAs) in the Kattegat-Skagerrak region
- 2014
-
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.
|
|
| 14. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
-
Larval connectivity and marine protected area networks
- 2020
-
Ingår i: In: Anger K, Harzsch S, Thiel M. Developmental biology and larval ecology: Natural history of crustaceans, Vol 7. - New York : Oxford University Press. - 9780190648954 ; , s. 408-436
-
Bokkapitel (refereegranskat)
|
|
| 15. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
-
Methods for estimating decapod larval supply and settlement: importance of larval behavior and development stage
- 2001
-
Ingår i: Marine Ecology-Progress Series. ; 209, s. 257-273
-
Tidskriftsartikel (refereegranskat)abstract
- In marine benthic organisms with a pelagic larval phase, assessment of recruitment regulation necessitates accurate estimates of larval supply and initial settlement densities. We assessed 2 commonly used methods for estimating decapod larval supply, plankton net tows and artificial settlement substrates (ASS), together with a new technique using passive-migration traps. The aim was to evaluate how these methods estimate larval supply and settlement of 3 common decapod species (the shore crab Carcinus maenas L., the brown shrimp Crangon crangon L, and the grass shrimps Palaemon spp.) in a microtidal nursery area on the Swedish west coast. and to assess how these estimates relate to the juvenile recruitment of these species. Discrete plankton net tows outside the shallow nursery area collected a higher proportion of larvae at an early development stage, compared to the other methods. and produced only a snapshot of the variable water-column abundance of shore crab and grass shrimp larvae that correlated poorly with numbers collected with ASS at the same location. Artificial settlement substrates appeared to produce good, integrated relative estimates of shore crab larval supply and settlement. The number of larvae collected from ASS correlated significantly with larval abundance estimated by passive-migration traps in shallow nursery areas, and reflected changes in shore crab settlement densities in caged mussel habitats. We did not detect any effect of predation on ASS placed in nursery areas. However, a large proportion tan estimated 83%) of shore crab postlarvae appeared to emigrate from ASS immersed for periods longer than 12 h, possibly during the night. All grass shrimp larvae appeared to emigrate from the collectors within 24 h, suggesting that ASS immersed longer than 12 h do not produce useful integrated estimates of larval supply for this species. These results demonstrate the importance of assessing postlarval emigration patterns from ASS to optimize immersion and collection time, and to avoid confounded estimates of larval abundance and settlement. PI new method using replicated passive migration traps that fished continuously in opposite directions ton-shore and off-shore) gave promising integrated estimates of net fluxes (total number immigrating minus number emigrating per unit time) of both pelagic postlarvae and early benthic juvenile stages of crabs and shrimp. The majority of the brown shrimp recruits were young juveniles, demonstrating the importance of incorporating juvenile migration in recruitment studies of motile benthic species. High numbers of shore crab and grass shrimp larvae were found to emigrate from the bay, indicating that many decapod postlarvae found in nursery areas may be transitional. The emigrating larvae were on average in an earlier development stage than those migrating to the bay. These short-term experiments demonstrate the importance of assessing larval development stage and migratory behavior when estimating larval supply and settlement for recruitment studies.
|
|
| 16. |
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
- Pihl, Leif, 1951, et al.
(författare)
-
Distribution of green algal mats throughout shallow soft bottoms of the Swedish Skagerrak archipelago in relation to nutrient sources and wave exposure
- 1999
-
Ingår i: Journal of Sea Research. ; 41:4, s. 281-294
-
Tidskriftsartikel (refereegranskat)abstract
- Distribution and biomass of green algal mats were studied in marine shallow (0-1 m) soft-bottom areas on the Swedish west coast from 1994 to 1996, by combining aerial photography surveys with ground truth sampling. Filamentous green algae, dominated by species of the genera Cladophora and Enteromorpha, were generally present throughout the study area during July and August, and largely absent in late April and early May. These algae occurred at 60 to 90% of the locations investigated during the summer, and were estimated to cover between 30 and 50% of the total area of shallow soft bottoms of the Swedish Skagerrak archipelago. The distributional patterns were similar during the three years of the investigation and appeared unrelated to annual local nutrient inputs from point sources and river discharge. We postulate that the apparent lack of such a relationship is due to an altered state of nutrient dynamics throughout the archipelago. Mechanisms are likely to involve long-term, diffuse elevations in nutrient levels in coastal waters of the Skagerrak and the Kattegat over several decades leading to current eutrophic conditions, exceeding nutrient requirements for abundant filamentous algal growth. Patterns of algal abundance in our study were largely related to physical factors such as exposure to wind, waves and water exchange under conditions where nutrient loads among embayments seemed to be unlimited. Further, our results show that sediments covered by algal mats had higher carbon and nitrogen contents than unvegetated sediments. We hypothesise that sustained high nutrient loads, manifested in extensive biomass of filamentous algae during summer months, are re-mineralised via decay and sedimentation in the benthic realm. Hence, accumulated carbon and nutrients in the sediment could, in turn, constitute the basic pool for future algal mat production overlying soft bottoms in areas where tidal exchange is limited. (C) 1999 Elsevier Science B.V. All rights reserved.
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Svensson, Carl Johan, 1976, et al.
(författare)
-
Temporal mismatches in predator-herbivore abundance control algae blooms in nutrient-enriched seagrass ecosystems.
- 2012
-
Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 471, s. 61-71
-
Tidskriftsartikel (refereegranskat)abstract
- Blooming filamentous algae recurrently overgrow macroalgae and seagrass in many coastal ecosystems, leading to potential losses in the functions and services these habitats provide. The seasonal reoccurrence of algal blooms is partly caused by excessive input of nutrients into coastal ecosystems. At the same time, overfishing of top predators has led to increased densities of smaller predators that reduce herbivore abundance. Managers of coastal ecosystems are in urgent need of information on how overfishing may act synergistically with eutrophication to promote algal blooms. In the present study, we model the interaction between the opportunistic filamentous algae Ulva spp. and the effective mesograzer (small invertebrate herbivore) Gammarus locusta L. under different nutrient regimes and predation rates by intermediate-size fish (4 to 12 cm). The aim is to assess how productivity, herbivory and predation interact to regulate seasonal algal growth under a range of scenarios, including temporal matching or mismatching between trophic groups. The model is parameterised with nutrient and demographic data from a seagrass ecosystem on the west coast of Sweden. Model simulations show that both nutrient level and herbivore abundance regulate seasonal algal biomass in the seagrass meadow. Their relative importance is dynamic and sensitive to the arrival times of herbivores in relation to the start of algal development in spring. Thus, herbivore presence and timing are crucial factors for the control of algal biomass, particularly during times when resource levels are ambient to slightly elevated. Simulations also show that it is mainly the predation rate and timing of predators, rather than food limitation, that limit herbivore abundance. As predation rates by invertebrates and smaller fish can be linked to the presence of larger and commercially targeted fish, overfishing may have similar effects to eutrophication in the seagrass ecosystems.
|
|
| 25. |
- Turner, Lucy M., et al.
(författare)
-
Transporting ideas between marine and social sciences: experiences from interdisciplinary research programs
- 2017
-
Ingår i: Elementa. - : University of California Press. - 2325-1026. ; 5:14
-
Tidskriftsartikel (refereegranskat)abstract
- The oceans comprise 70% of the surface area of our planet, contain some of the world’s richest natural resources and are one of the most significant drivers of global climate patterns. As the marine environment continues to increase in importance as both an essential resource reservoir and facilitator of global change, it is apparent that to find long-term sustainable solutions for our use of the sea and its resources and thus to engage in a sustainable blue economy, an integrated interdisciplinary approach is needed. As a result, interdisciplinary working is proliferating. We report here our experiences of forming interdisciplinary teams (marine ecologists, ecophysiologists, social scientists, environmental economists and environmental law specialists) to answer questions pertaining to the effects of anthropogenic-driven global change on the sustainability of resource use from the marine environment, and thus to transport ideas outwards from disciplinary confines. We use a framework derived from the literature on interdisciplinarity to enable us to explore processes of knowledge integration in two ongoing research projects, based on analyses of the purpose, form and degree of knowledge integration within each project. These teams were initially focused around a graduate program, explicitly designed for interdisciplinary training across the natural and social sciences, at the Gothenburg Centre for Marine Research at the University of Gothenburg, thus allowing us to reflect on our own experiences within the context of other multi-national, interdisciplinary graduate training and associated research programs.
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
- Aronson, Richard, et al.
(författare)
-
No barrier to emergence of bathyal king crabs on the Antarctic shelf
- 2015
-
Ingår i: Proceedings of the National Academy of Science of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 112:42, s. 12997-13002
-
Tidskriftsartikel (refereegranskat)abstract
- Cold-water conditions have excluded durophagous (skeleton-breaking) predators from the Antarctic seafloor for millions of years. Rapidly warming seas off the western Antarctic Peninsula could now facilitate their return to the continental shelf, with profound consequences for the endemic fauna. Among the likely first arrivals are king crabs (Lithodidae), which were discovered recently on the adjacent continental slope. During the austral summer of 2010‒2011, we used underwater imagery to survey a slope-dwelling population of the lithodid Paralomis birsteini off Marguerite Bay, western Antarctic Peninsula for environmental or trophic impediments to shoreward expansion. The population density averaged ∼4.5 individuals × 1,000 m−2 within a depth range of 1,100‒1,500 m (overall observed depth range 841–2,266 m). Images of juveniles, discarded molts, and precopulatory behavior, as well as gravid females in a trapping study, suggested a reproductively viable population on the slope. At the time of the survey, there was no thermal barrier to prevent the lithodids from expanding upward and emerging on the outer shelf (400- to 550-m depth); however, near-surface temperatures remained too cold for them to survive in inner-shelf and coastal environments (<200 m). Ambient salinity, composition of the substrate, and the depth distribution of potential predators likewise indicated no barriers to expansion of lithodids onto the outer shelf. Primary food resources for lithodids—echinoderms and mollusks—were abundant on the upper slope (550–800 m) and outer shelf. As sea temperatures continue to rise, lithodids will likely play an increasingly important role in the trophic structure of subtidal communities closer to shore.
|
|
| 29. |
- Baden, Susanne P., 1952, et al.
(författare)
-
Gödning och överfiske förstör fiskens barnkammare
- 2005
-
Ingår i: Miljöforskning för ett uthålligt samhälle: I havets dunkla djup. - 1650-4925. ; 4
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Nya resultat visar att övergödning och överfiske gynnar vissa faunagrupper så att alger kväver det viktiga ålgräset, som utgör barnkammare för torsk och abborre. Ålgräset har minskat med 60 procent på 20 år skriver Susanne P Baden och Per O Moksnes i artikeln Gödning och överfiske förstör fiskens barnkammare.
|
|
| 30. |
- Baden, Susanne P., 1952, et al.
(författare)
-
Relative importance of trophic interactions and nutrient enrichment in seagrass ecosystems: A broad-scale field experiment in the Baltic-Skagerrak area.
- 2010
-
Ingår i: Limnology and Oceanography. - 1541-5856. ; 55:3, s. 1435-1448
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction of eutrophication and predation in structuring seagrass Zostera marina L. ecosystems was assessed in a field experiment in three regions along an estuarine salinity gradient, from southern Finland to the Skagerrak area of the Swedish west coast. All regions are considered to be affected by eutrophication and overfishing but differ in the abundance of intermediate predators (e.g., small fish, shrimp, and crabs), mesograzers, and the biomass of epiphytic algae. Using transplanted Zostera (eelgrass), nutrient levels and intermediate predator abundance were manipulated in a full-factorial cage experiment. On the Swedish west coast, where ambient densities of mesograzers are very low, epiphytic algae responded strongly to nutrient enrichment, resulting in significantly reduced growth of eelgrass. At the Baltic sites however, where ambient densities of mesograzers are high, no significant growth of epiphytic algae was detected, and only grazer biomass responded to nutrient enrichment. Predation from small fish, shrimp, and crabs decreased the biomass of mesograzers by . 98% on the Swedish west coast, but natural predators had no significant effect on mesograzers biomass at the Baltic sites. Predation and nutrient enrichment interacted to affect the growth of eelgrass by controlling the biomass of mesograzers and nuisance algae. The differing effect of nutrient enrichment and grazing in the three regions may therefore be a result of the prevailing low and high predation pressure on mesograzers in Zostera. This absence or presence of predation may derive from interregional changes in trophic interactions, possibly caused by a combination of eutrophication and overfishing.
|
|
| 31. |
|
|
| 32. |
- Cole, Scott, et al.
(författare)
-
Environmental compensation for biodiversity and ecosystem services : A flexible framework that addresses human wellbeing
- 2021
-
Ingår i: Ecosystem Services. - : Elsevier BV. - 2212-0416 .- 2212-0416. ; 50
-
Tidskriftsartikel (refereegranskat)abstract
- Environmental compensation should address negative impacts from human activities on nature, including loss of biodiversity and ecosystem services. However, successful compensation, achieving no net loss, requires broad quantitative information on different types of losses and gains. We find that the scope of compensatory schemes varies in what is considered compensable, which makes it challenging to apply a conceptual approach consistently across schemes with different needs. We propose a flexible yet structured framework for determining which values should be compensated and how. Our framework focuses specifically on habitat deterioration and is illustrated with a case study involving loss of eelgrass habitat. The framework helps identify compensation needs and selects among suitable compensation options, merging science-based information with normative issues and local concerns. By integrating the ecosystem services cascade model, it encompasses aspects from biodiversity structure to human wellbeing. The framework prefers in-kind compensation because this targets the structure level and thus meets compensation needs in all subsequent levels of the cascade model; further, it is more likely to capture non-instrumental values (i.e. in nature) and reduce exposure to uncertainty. We highlight the importance of spatial aspects of ecosystem functions, services and their subsequent impacts on wellbeing. Although our selection hierarchy assumes a similar and nearby principle for habitat restoration (preference for in-kind/on-site), this criterion is not universal. We underscore the hierarchy's implicit normative assumptions and suggest that apparent disagreement about who should benefit may be traced to an unresolved conflict between egalitarianism and utilitarianism.
|
|
| 33. |
- Cole, Scott, et al.
(författare)
-
Valuing multiple eelgrass ecosystem services in Sweden: fish production and uptake of carbon and nitrogen
- 2016
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 2:artikel nr 121
-
Tidskriftsartikel (refereegranskat)abstract
- Valuing nature’s benefits in monetary terms is necessary for policy-makers facing trade-offs in how to spend limited financial resources on environmental protection. We provide information to assess trade-offs associated with the management of seagrass beds, which provide a number of ecosystem services, but are presently impacted by many stressors. We develop an interdisciplinary framework for valuing multiple ecosystem services and apply it to the case of eelgrass (Zostera marina), a dominant seagrass species in the northern hemisphere. We identify and quantify links between three eelgrass functions (habitat for fish, carbon, and nitrogen uptake) and economic goods in Sweden, quantify these using ecological endpoints, estimate the marginal average value of the impact of losing one hectare of eelgrass along the Swedish northwest coast on welfare in monetary terms, and aggregate these values while considering double-counting. Over a 20–50 year period we find that compared to unvegetated habitats, a hectare of eelgrass, including the organic material accumulated in the sediment, produces an additional 626 kg cod fishes and 7535 wrasse individuals and sequesters 98.6 ton carbon and 466 kg nitrogen. We value the flow of future benefits associated with commercial fishing, avoided climate change damages, and reduced eutrophication at 170,000 SEK in 2014 (20,700 US$) or 11,000 SEK (1300 US$) annualized at 4%. Fish production, which is the most commonly valued ecosystem service in the seagrass literature, only represented 25% of the total value whereas a conservative estimate of nitrogen regulation constituted 46%, suggesting that most seagrass beds are undervalued. Comparing these values with historic losses of eelgrass we show that the Swedish northwest coast has suffered a substantial reduction in fish production and mineral regulation. Future work should improve the understanding of the geographic scale of eelgrass functions, how local variables affect the value of these functions, and how to defensibly aggregate a multitude of economic values.
|
|
| 34. |
- Duffy, J. Emmett, et al.
(författare)
-
A Pleistocene legacy structures variation in modern seagrass ecosystems
- 2022
-
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. ; 119:32
-
Tidskriftsartikel (refereegranskat)abstract
- Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.
|
|
| 35. |
- Duffy, J. E., et al.
(författare)
-
Biodiversity mediates top-down control in eelgrass ecosystems: a global comparative-experimental approach
- 2015
-
Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 18:7, s. 696-705
-
Tidskriftsartikel (refereegranskat)abstract
- Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors.
|
|
| 36. |
- Duffy, J. E., et al.
(författare)
-
Ecology of seagrass communities
- 2014
-
Ingår i: Marine Community Ecology and Conservation, M. D. Bertness et al. (eds). - Sunderland, USA : Sinauer Associates Inc.. - 9781605352282 ; , s. 271-297
-
Bokkapitel (refereegranskat)
|
|
| 37. |
- Eklöf, Johan, 1978, et al.
(författare)
-
Sjögräsängar - hotade av både övergödning och överfiske?
- 2009
-
Ingår i: HavsUtsikt: Om svensk havsforskning och havets resurser. - 1104-0513. ; 1
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Sjögräsängar är viktiga som barnkammare för många fiskarter, men är hotade av människan genom bland annat övergödning. Nu visar resultat från forskning utförd av svenska forskare i Sverige och i Östafrika på att även överfiske av stora rovfiskar skulle kunna ge negativa effekter på sjögräset. Detta visar hur viktigt det är att man inom förvaltningen använder sig av en kombination av åtgärder när sjögräsängarna ska räddas.
|
|
| 38. |
- Eriander, Louise, 1984, et al.
(författare)
-
Assessing methods for restoration of eelgrass (Zostera marina L.) in a cold temperate region
- 2016
-
Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 479, s. 76-88
-
Tidskriftsartikel (refereegranskat)abstract
- More than 50% of eelgrass habitats have disappeared from the Swedish NW coast in the last 30 years. Restoration is being proposed to assist recovery but little is known regarding methods suitable under Scandinavian conditions; e.g. short growing seasons and scouring by ice. In the present study we evaluated different restoration methods using shoots and seeds in a Swedish fjord and assessed if eelgrass could be successfully transplanted between sites with different depth and exposure. The study demonstrates that both shoot- and seed methods can be successfully used to restore eelgrass at this latitude. Survival and growth of unanchored single shoots, transplanted without sediment in shallow habitats (1.0–1.5 m) was very high (> 500% increase in shoot density after 14 months). This restoration method showed 2–3.5 times higher growth rate and was 2–2.5 times faster compared with shoots anchored in the sediment and shoots transplanted in sediment cores, respectively, and is recommended for shallow habitats in Sweden. Growth within deeper habitats (3.0–4.5 m) was substantially lower (40% loss to 50% increase) due to light limitations and high winter mortality. Restoration using seeds distributed from mesh-bags showed very low seedling establishment rates (approximately 1%) making this method less cost-effective than transplanting single shoots in shallow habitats. However, growth of seedlings was high and this method is recommended for deep habitats with soft sediment where shoot transplantation is difficult. Despite dramatic differences in eelgrass morphology between habitats with different depth and exposure, all shoots within a planting site had the same morphology at the end of the study, independent of origin. A baseline genetic survey supported that the observed changes in morphology of transplants were due to a plastic response, suggesting that donor populations do not have to exactly match the morphology of the plants targeted for restoration.
|
|
| 39. |
|
|
| 40. |
- Gagnon, Karine, et al.
(författare)
-
Rapid faunal colonization and recovery of biodiversity and functional diversity following eelgrass restoration
- 2023
-
Ingår i: Restoration Ecology. - : Wiley. - 1061-2971 .- 1526-100X. ; 31
-
Tidskriftsartikel (refereegranskat)abstract
- Seagrass meadows and their associated biodiverse assemblages have declined globally due to environmental and anthropogenic stressors. Restoration of these critical habitats has the potential to reverse coastal biodiversity loss. Here, we tested the role of patch size (which can affect recruitment, food availability, and/or predation) in driving faunal colonization in an eelgrass (Zostera marina) restoration trial in Sweden. Eelgrass shoots were transplanted in plots with different configurations (contin- uous vs. checkerboard patterns with three patch sizes), and we followed invertebrate colonization (biodiversity and functional diversity) during the first two growing seasons. We found rapid faunal colonization following the transplantation of eelgrass shoots in all plots with invertebrate densities reaching 50–80% of the reference meadow after only one growing season (3 months). After two growing seasons (15 months), the faunal density, biodiversity, and functional diversity were similar to the reference meadow, despite eelgrass density and biomass still being lower than the reference meadow. Biodiversity, func- tional diversity, and community structure were similar among the different planted plots, that is, there was no indication that patch size influenced faunal colonization. We therefore consider that smaller patches embedded within larger restoration plots can be as effective for promoting biodiversity as continuous patches, with reduced costs and fewer shoots required. We also noted high natural variability between years both in the reference meadow and planted plots, showing the dynamic nature of seagrass ecosystems, and the importance of a well-planned monitoring scheme that considers the reference area and restored area within the same temporal scale.
|
|
| 41. |
|
|
| 42. |
- Gross, C. P., et al.
(författare)
-
The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans
- 2022
-
Ingår i: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 289:1969
-
Tidskriftsartikel (refereegranskat)abstract
- While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.
|
|
| 43. |
- Hedvall, Ola, et al.
(författare)
-
Active habitat selection by megalopae and juvenile shore crabs Carcinus maenas: a laboratory study in an annular flume
- 1998
-
Ingår i: Hydrobiologia. - 0018-8158 .- 1573-5117. ; 376, s. 89-100
-
Tidskriftsartikel (refereegranskat)abstract
- We studied megalopae (postlarvae) and young juveniles of the shore crab (Carcinus maenas L.) in laboratory experiments to examine four potentially important processes for juvenile distribution and recruitment: (1) hydrodynamic processes and passive deposition of megalopae, (2) active habitat selection of megalopae, (3) habitat specific predation rates, and (4) active habitat selection by juveniles. In an annular flume, simulating natural current velocities in nursery areas on the Swedish west coast, we assessed the distribution of dead megalopae, Live megalopae, live megalopae with predators (juvenile conspecifics and brown shrimp, Crangon crangon), and first instar crabs, in four simultaneously presented habitats: blue mussels (Mytilus edulis), eelgrass (Zostera marina), filamentous green algae (Cladophora sp. and Chaetomorpha linum) and bare sand. In a second experiment we studied the distribution of Live megalopae between four different ephemeral macroalgae with different structural complexity (Ulva lactuca, Enteromorpha sp., Cladophora sp. and Ectocarpus siliculosus). Dead megalopae were evenly distributed between the four habitats, whereas all other treatments showed significantly lower proportions of megalopae and juvenile crabs in the sand habitat (0-2%) compared to the structurally complex habitats (24-40%). The distribution between mussels, eelgrass and filamentous algae of live megalopae in absence of predators did not differ significantly from the hydrodynamical null hypothesis, i.e. distribution of dead megalopae. However, predation increased the proportion of megalopae significantly in the filamentous algae, providing the best refuge from predation of these habitats. First instar crabs showed a significantly different distribution compared to megalopae, with higher proportion in the algal habitat, whereas juvenile predatory crabs were found in significantly higher proportion among mussels. Megalopae selected all four different macroalgae species over open sand, but a significantly lower proportion were found in the algae with the highest structural complexity (Ectocarpus siliculosus; 14%) compared to the other algal species (26-30%). These results indicate that passive deposition have Little influence on the small scale (< 10 s of meters) distribution of shore crab megalopae during normal current velocities, but that active habitat selection by megalopae is the major process responsible for the non-random distribution of megalopae and juvenile shore crabs. The results further suggest that the initial distribution of megalopae between nursery habitats is quickly modified by habitat specific predation rates and size-specific movements and habitat choices by juveniles. The correlation between the habitat choice of megalopae and juvenile crabs, and the refuge value of the examined habitats suggests that habitat specific predation rates is a major selective force behind the behavior of active habitat selection in this species.
|
|
| 44. |
|
|
| 45. |
- Huber, S., et al.
(författare)
-
Novel approach to large-scale monitoring of submerged aquatic vegetation: A nationwide example from Sweden
- 2022
-
Ingår i: Integrated Environmental Assessment and Management. - : Wiley. - 1551-3777 .- 1551-3793. ; 18:4, s. 909-20
-
Tidskriftsartikel (refereegranskat)abstract
- According to the EU Habitats directive, the Water Framework Directive, and the Marine Strategy Framework Directive, member states are required to map, monitor, and evaluate changes in quality and areal distribution of different marine habitats and biotopes to protect the marine environment more effectively. Submerged aquatic vegetation (SAV) is a key indicator of the ecological status of coastal ecosystems and is therefore widely used in reporting related to these directives. Environmental monitoring of the areal distribution of SAV is lacking in Sweden due to the challenges of large-scale monitoring using traditional small-scale methods. To address this gap, in 2020, we embarked on a project to combine Copernicus Sentinel-2 satellite imagery, novel machine learning (ML) techniques, and advanced data processing in a cloud-based web application that enables users to create up-to-date SAV classifications. At the same time, the approach was used to derive the first high-resolution SAV map for the entire coastline of Sweden, where an area of 1550 km(2) was mapped as SAV. Quantitative evaluation of the accuracy of the classification using independent field data from three different regions along the Swedish coast demonstrated relative high accuracy within shallower areas, particularly where water transparency was high (average total accuracy per region 0.60-0.77). However, the classification missed large proportions of vegetation growing in deeper water (on average 31%-50%) and performed poorly in areas with fragmented or mixed vegetation and poor water quality, challenges that should be addressed in the development of the mapping methods towards integration into monitoring frameworks such as the EU directives. In this article, we present the results of the first satellite-derived SAV classification for the entire Swedish coast and show the implementation of a cloud-based SAV mapping application (prototype) developed within the frame of the project. Integr Environ Assess Manag 2021;00:1-12. (c) 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
|
|
| 46. |
- Infantes, Eduardo, et al.
(författare)
-
Eelgrass seed harvesting: Flowering shoots development and restoration on the Swedish west coast
- 2018
-
Ingår i: Aquatic Botany. - : Elsevier BV. - 0304-3770. ; 144, s. 9-19
-
Tidskriftsartikel (refereegranskat)abstract
- © 2017 Elsevier B.V. Eelgrass (Zostera marina) flowering development and seed production were assessed along a depth gradient at three sites during 2012 and 2013 to 1) describe the flowering seasonality in the Swedish west coast, and 2) evaluate methods using seeds for large-scale restoration, including harvesting, storage and separation of viable seeds using a vertical flume. Eelgrass flowering shoots were found in the field from June to October, reaching the highest densities in July and August (average 3.8 ± 0.5 shoots m −2 ). Flowering shoot densities decreased with depth, whereas shoot length, number of spathes, seeds/shoot and seed size increased with depth, resulting in the highest seed production at intermediate depths (2 m) in most bays and years. Because of low densities of flowering shoots, seed production in Sweden (on average 39–126 seeds m −2 , Jul–Sep) was an order of magnitude lower than in other studied areas. Results showed that seed production differed 2.5–3.4 times between meadows and years, mainly driven by variation in seed production per shoot. This variation was only partly explained by temperature over the growing season, suggesting that other factors such as light and the amount of filamentous algal mats might also be important in flower development. Results suggest that flowering shoots should be harvested when > 50% of the spathes have developing seeds, and that shoots should not be stored longer than 40 days in tanks to obtain an optimal release of viable seeds. A new mechanized method using a vertical flume to separate large amounts of viable seeds from the harvest is also presented.
|
|
| 47. |
- Infantes, Eduardo, et al.
(författare)
-
Eelgrass (Zostera marina L.) restoration methods using seeds on the west coast of Sweden
- 2016
-
Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 546, s. 31-45
-
Tidskriftsartikel (refereegranskat)abstract
- Along the northwest coast of Sweden, over 50% of Zostera marina L. (eelgrass) meadows have vanished since the 1980s. With the improvement of conditions, there is a growing interest to restore lost habitats, but methods are lacking for restoration of eelgrass beds at high latitudes where long winters create special challenges. We assessed if seed planting could be used for large-scale restoration, with the aim to identify the major causes of seed and seedling loss and to determine which planting method best increases restoration success. In the laboratory, we identified optimal conditions for long-term seed storage and demonstrated that eelgrass seeds can be successfully stored for 8 mo before being planted in the spring. However, field studies did not find an increased seedling establishment in seeds planted in the spring of 2013 compared to those planted in the fall of 2012. Field results suggest that the main causes for the seed loss were seed predation from crabs, seed transport by currents and bioturbation by lugworms, while the main processes affecting shoot development were light availability and physical disturbance. Covering the seeds with a layer of sand increased seedling establishment 2 to 6 times compared to uncovered seeds, probably through the reduction of seed predation and seed transport, and could potentially be developed as a method to reduce losses during restoration. In addition, positive feedback mechanisms (i.e. sediment resuspension and drifting macroalgae mats) may also prevent natural recovery and restoration success. However, high seed loss (on average 98.6%) and high shoot mortality pose a challenge that need to be addressed before restoration using seeds can be recommended for large-scale restoration.
|
|
| 48. |
- Infantes, Eduardo, et al.
(författare)
-
Seed predation by the shore crab Carcinus maenas: a positive feedback preventing recovery of eelgrass Zostera marina?
- 2016
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:12
-
Tidskriftsartikel (refereegranskat)abstract
- There is an increasing interest to restore the ecosystem services that eelgrass provides, after their continuous worldwide decline. Most attempts to restore eelgrass using seeds are challenged by very high seed losses and the reasons for these losses are not all clear. We assess the impact of predation on seed loss and eelgrass establishment, and explore methods to decrease seed loss during restoration in the Swedish northwest coast. In a laboratory study we identified three previously undescribed seed predators, the shore crab Carcinus maenas, the hermit crab Pagurus bernhardus and the sea urchin Strongylocentrotus droebachiensis, of which shore crabs consumed 2–7 times more seeds than the other two species. The importance of shore crabs as seed predators was supported in field cage experiments where one enclosed crab caused 73% loss of seeds over a 1-week period on average (~ 21 seeds per day). Seedling establishment was significantly higher (14%) in cages that excluded predators over an 8-month period than in uncaged plots and cages that allowed predators but prevented seed-transport (0.5%), suggesting that seed predation constitutes a major source of seed loss in the study area. Burying the seeds 2 cm below the sediment surface prevented seed predation in the laboratory and decreased predation in the field, constituting a way to decrease seed loss during restoration. Shore crabs may act as a key feedback mechanism that prevent the return of eelgrass both by direct consumption of eelgrass seeds and as a predator of algal mesograzers, allowing algal mats to overgrow eelgrass beds. This shore crab feedback mechanism could become self-generating by promoting the growth of its own nursery habitat (algal mats) and by decreasing the nursery habitat (seagrass meadow) of its dominant predator (cod). This double feedback-loop is supported by a strong increase of shore crab abundance in the last decades and may partly explain the regime shift in vegetation observed along the Swedish west coast.
|
|
| 49. |
- Kindeberg, T., et al.
(författare)
-
Variation of carbon contents in eelgrass (Zostera marina) sediments implied from depth profiles
- 2019
-
Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 15:6
-
Tidskriftsartikel (refereegranskat)abstract
- Seagrass meadows are able to store significant amounts of organic carbon in their underlying sediment, but global estimates are uncertain partly owing to spatio-temporal heterogeneity between and within areas and species. In order to provide robust estimates, there is a need to better understand the fate of, and mechanisms behind, organic carbon storage. In this observational study, we analyse a suite of biotic and abiotic parameters in sediment cores from 47 different eelgrass (Zostera marina) beds spanning the distributional range of the Northern Hemisphere. Depth profiles of particulate organic carbon (POC) revealed three patterns of vertical distribution where POC either increased, decreased or showed no pattern with sediment depth. These categories exhibited distinct profiles of δ13C and C:N ratios, where high POC profiles had a proportionally larger storage of eelgrass-derived material whereas low POC profiles were dominated by phytoplanktonic and macroalgal material. However, high POC did not always translate into high carbon density. Nevertheless, this large-scale dataset provides evidence that the variability in organic matter source in response to natural and anthropogenic environmental changes affects the potential role of eelgrass beds as POC sinks, particularly where eelgrass decline is observed. © 2019 The Author(s) Published by the Royal Society. All rights reserved.
|
|
| 50. |
|
|
