| 1. |
- Gross, C. P., et al.
(author)
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The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans
- 2022
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In: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 289:1969
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Journal article (peer-reviewed)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.
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| 2. |
- Eklöf, Johan S., 1978-, et al.
(author)
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Effects of seasonal spawning closures on pike (Esox lucius L.) and perch (Perca fluviatilis L.) catches and coastal food webs in the western Baltic Sea
- 2023
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In: Fisheries Research. - : Elsevier BV. - 0165-7836 .- 1872-6763. ; 263
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Journal article (peer-reviewed)abstract
- Marine protected areas have become one of the main tools in the battle to curb marine biodiversity loss and habitat degradation. Yet, implementation of permanent fishery closures has often generated resource user conflicts that ultimately undermine conservation goals. Here we assessed the influence of an alternative and often more accepted measure – seasonal fish spawning closures – on large predatory fish and coastal food webs in the western Baltic Sea (Sweden). In spring 2017, we conducted a multivariable field survey in 11 seasonal closures and 11 paired references areas open to fishing. In each area, pike was sampled through angling, and perch and mesopredators through gillnet surveys. To assess trophic cascades, we measured zooplankton abundance and loss of tethered gammarids from predation. Catches per unit effort of northern pike (Esox lucius) – the main target species in recreational fisheries – were ca. 2.5 times higher per unit effort in closures than reference areas; an effect that may be caused by higher abundance and/or higher catchability of pike in the absence of fishing. Catch and weight per unit effort of the more common predator European perch (Perca fluviatilus), and the mesopredators roach (Rutilus rutilus) and three-spined stickleback (Gasterosteus aculeatus) in survey nets were, however, unaffected by closures. Moreover, a previously hypothesized trophic cascade from perch to zooplankton via three-spined stickleback was supported by the analyses, but appeared independent of closures. Yet, predation risk for tethered gammarid amphipods (a prey of stickleback and an important grazer on macroalgae) was three times higher in fished areas than in closures; a cascading closure effect that may potentially be caused by small predatory fish being less active in protected areas to avoid pike predation. Overall, our results suggest that spawning closures impact pike abundance and/or behavior and could help limit the effects of fishing, but that more research is needed to disentangle i) what mechanism(s) that underlie the protection effect on pike catches, ii) the apparently weaker closure impacts on other fish species, as well as iii) the potential for cascading effects on lower trophic levels. Therefore, new seasonal spawning closures should be implemented in addition to (and not instead of) much-needed permanent closures, which have well-known effects on the wider ecosystem.
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| 3. |
- Jones, Benjamin L. H., et al.
(author)
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Dependence on seagrass fisheries governed by household income and adaptive capacity
- 2022
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In: Ocean and Coastal Management. - : Elsevier BV. - 0964-5691 .- 1873-524X. ; 225
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Journal article (peer-reviewed)abstract
- Seagrass meadows, like other tropical coastal ecosystems, are highly productive and sustain millions of people worldwide. However, the factors that govern the use of seagrass as a fishing habitat over other habitats are largely unknown, especially at the household scale. Using socioeconomic factors from 147 villages across four countries within the Indo-Pacific, we examined the drivers of household dependence on seagrass. We revealed that seagrass was the most common habitat used for fishing across villages in all the countries studied, being preferred over other habitats for reliability. Using structural equation modelling, we exposed how household income and adaptive capacity appears to govern dependence on seagrass. Poorer households were less likely to own motorboats and dependent on seagrass as they were unable to fish elsewhere, whereas wealthier households were more likely to invest in certain fishing gears that incentivised them to use seagrass habitats due to high rewards and low effort requirements. Our findings accentuate the complexity of seagrass social-ecological systems and the need for empirical household scale data for effective management. Safeguarding seagrass is vital to ensure that vulnerable households have equitable and equal access to the resource, addressing ocean recovery and ensuring sustainable coastal communities.
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| 4. |
- Niemi, Niklas, et al.
(author)
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Influence of reed beds (Phragmites australis) and submerged vegetation on pike (Esox lucius)
- 2023
-
In: Fisheries Research. - : Elsevier BV. - 0165-7836 .- 1872-6763. ; 261
-
Journal article (peer-reviewed)abstract
- Eutrophication and reduced grazing have led to an expansion of the common reed (Phragmites australis) in archipelago areas in the Baltic Sea, while at the same time the composition of submerged vegetation has changed. Although reed is important as nursery habitat for many fish species, extensive emergent vegetation may reduce biodiversity and abundance of predatory fish. Pike (Esox lucius) is a predatory fish whose larvae and young-of-the-year find both food and shelter in reed but use different micro-habitats during different life-stages. Here we investigate the influence of reed and submerged vegetation on abundance and body size of adult pike during the spawning season. We predicted that coastal bays with extensive but heterogeneous reed beds with higher cover of submerged vegetation would have more and larger pike than bays with smaller, homogenous reed belts or with less submerged vegetation. To test these predictions, we estimated abundance and size-structure of adult pike from catches in angling fishing among 22 bays in the Stockholm archipelago at the Swedish Baltic Sea coast. Our analyses show that catches of adult pike were positively associated with both extensive reed beds and cover of rooted submerged vegetation. However, pike size was not correlated with any vegetation variable, but instead increased with wave exposure and bay area. Our study suggests that reed beds and submerged vegetation are important for adult pike during the spawning season, and even the most extensive reed beds had no evident negative effect on pike populations. We could not see any clear relationship between emergent reed habitat and cover of submerged vegetation among the studied bays, and conclude that to maintain pike population during the spawning season it is important that coastal bays have sufficient amounts of both reed beds and rooted submerged vegetation.
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| 5. |
- Austin, Åsa N., 1988-, et al.
(author)
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Stronger effect of individual species’ traits than shading on aquatic plant community productivity and interspecific competition
- 2023
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In: Aquatic Botany. - : Elsevier BV. - 0304-3770 .- 1879-1522. ; 187
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Journal article (peer-reviewed)abstract
- Competition is one of the major factors structuring plant communities. Species with similar traits generally compete more intensely and have more similar yield than functionally dissimilar species, which often respond differently to environmental change. Little is known about how the interacting species’ traits influence the effect of environmental change on interspecific competition. However, theory predicts that environmental change should lead to more asymmetric competition, by favouring the species best adapted to the particular environmental change. Here we used a mesocosm experiment with three common aquatic plant species from the Baltic Sea (Northern Europe), to test how community productivity and competition asymmetry were affected by functional dissimilarity, individual species’ traits and a common stressor: shading. Competition asymmetry was defined as the absolute difference in reductions in yield relative to monocultures of two interacting species. Community productivity decreased and competition asymmetry increased with functional dissimilarity of the interacting species, possibly explained by the traits of the superior species, which had higher specific leaf area, maximum canopy height and primary production rate than the subordinate species. Community productivity was not affected by shading, contrary to our expectation, while competition asymmetry was higher in shaded than ambient conditions. Individual species yield depended on species identity and species combination. Only the shortest species was negatively affected by shading. Thus, by favouring tall-growing species, shading can alter interspecific competition. Together, these findings suggest that non-random species loss following environmental change can be caused by competitive exclusion, in addition to a direct effect of abiotic filtering.
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| 6. |
- de Fouw, Jimmy, et al.
(author)
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A facultative mutualism facilitates European seagrass meadows
- 2023
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In: Ecography. - 0906-7590 .- 1600-0587. ; 2023:5
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Journal article (peer-reviewed)abstract
- Coastal ecosystem functioning often hinges on habitat-forming foundation species that engage in positive interactions (e.g. facilitation and mutualism) to reduce environmental stress. Seagrasses are important foundation species in coastal zones but are rapidly declining with losses typically linked to intensifying global change-related environmental stress. There is growing evidence that loss or disruption of positive interactions can amplify coastal ecosystem degradation as it compromises its stress mitigating capacity. Multiple recent studies highlight that seagrass can engage in a facultative mutualistic relationship with lucinid bivalves that alleviate sulphide toxicity. So far, however, the generality of this mutualism, and how its strength and relative importance depend on environmental conditions, remains to be investigated. Here we study the importance of the seagrass-lucinid mutualistic interaction on a continental-scale using a field survey across Europe. We found that the lucinid bivalve Loripes orbiculatus is associated with the seagrasses Zostera noltii and Zostera marina across a large latitudinal range. At locations where the average minimum temperature was above 1 °C, L. orbiculatus was present in 79% of the Zostera meadows; whereas, it was absent below this temperature. At locations above this minimum temperature threshold, mud content was the second most important determinant explaining the presence or absence of L. orbiculatus. Further analyses suggest that the presence of the lucinids have a positive effect on seagrass biomass by mitigating sulphide stress. Finally, results of a structural equation model (SEM) support the existence of a mutualistic feedback between L. orbiculatus and Z. noltii. We argue that this seagrass-lucinid mutualism should be more solidly integrated into management practices to improve seagrass ecosystem resilience to global change as well as the success of restoration efforts.
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| 7. |
- Donadi, S., et al.
(author)
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Cross-habitat interactions among bivalve species control community structure on intertidal flats
- 2013
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In: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 94:2, s. 489-498
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Journal article (peer-reviewed)abstract
- Increasing evidence shows that spatial interactions between sedentary organisms can structure communities and promote landscape complexity in many ecosystems. Here we tested the hypothesis that reef-forming mussels (Mytilus edulis L.), a dominant intertidal ecosystem engineer in the Wadden Sea, promote abundances of the burrowing bivalve Cerastoderma edule L. (cockle) in neighboring habitats at relatively long distances coastward from mussel beds. Field surveys within and around three mussel beds showed a peak in cockle densities at 50–100 m toward the coast from the mussel bed, while cockle abundances elsewhere in the study area were very low. Field transplantation of cockles showed higher survival of young cockles (2–3 years old) and increased spat fall coastward of the mussel bed compared to within the bed and to areas without mussels, whereas growth decreased within and coastward of the mussel bed. Our measurements suggest that the observed spatial patterns in cockle numbers resulted from (1) inhibition effects by the mussels close to the beds due to preemptive algal depletion and deteriorated sediment conditions and (2) facilitation effects by the mussels farther away from the beds due to reduction of wave energy. Our results imply that these spatial, scale-dependent interactions between reef-forming ecosystem engineers and surrounding communities of sedentary benthic organisms can be an important determinant of the large-scale community structure in intertidal ecosystems. Understanding this interplay between neighboring communities of sedentary species is therefore essential for effective conservation and restoration of soft-bottom intertidal communities.
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| 8. |
- Duffy, J. Emmett, et al.
(author)
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A Pleistocene legacy structures variation in modern seagrass ecosystems
- 2022
-
In: 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
-
Journal article (peer-reviewed)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.
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| 9. |
- Eklöf, Johan S., 1978-
(author)
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Anthropogenic Disturbances and Shifts in Tropical Seagrass Ecosystems
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- Seagrasses constitute the basis for diverse and productive ecosystems worldwide. In East Africa, they provide important ecosystem services (e.g. fisheries) but are potentially threatened by increasing resource use and lack of enforced management regulations. The major aim of this PhD thesis was to investigate effects of anthropogenic distur-bances, primarily seaweed farming and coastal fishery, in East African seagrass beds. Seaweed farming, often depicted as a sustainable form of aquaculture, had short- and long-term effects on seagrass growth and abundance that cascaded up through the food web to the level of fishery catches. The coastal fishery, a major subsistence activity in the region, can by removing urchin predators indirectly increase densities of the sea urchin Tripneustes gratilla, which has overgrazed seagrasses in several areas. A study using simulated grazing showed that high magnitude leaf removal – typical of grazing urchins – affected seagrasses more than low magnitude removal, typical of fish grazing. Different responses in two co-occurring seagrass species furthermore indicate that high seagrass diversity in tropical seagrass beds could buffer overgrazing effects in the long run. Finally, a literature synthesis suggests that anthropogenic disturbances could drive shifts in seagrass ecosystems to an array of alternative regimes dominated by other or-ganisms (macroalgae, bivalves, burrowing shrimp, polychaetes, etc.). The formation of novel feedback mechanisms makes these regimes resilient to disturbances like seagrass recovery and transplantation projects. Overall, this suggests that resource use activities linked to seagrasses can have large-scale implications if the scale exceeds critical levels. This emphasizes the need for holistic and adaptive management at the seascape level, specifically involving improved techniques for seaweed farming and fisheries, protection of keystone species, and ecosystem-based management approaches.
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| 10. |
- Jones, Benjamin L. H., et al.
(author)
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Unintended consequences of sustainable development initiatives : risks and opportunities in seagrass social-ecological systems
- 2022
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In: Ecology and Society. - : Resilience Alliance, Inc.. - 1708-3087. ; 27:2
-
Journal article (peer-reviewed)abstract
- Conserving biodiversity with a growing human population is a key sustainability challenge. Consequently, a vast number of development initiatives across the globe have been designed to combine social, economic, and environmental perspectives. For the most part, the development community is well acquainted with the negative experiences and unintended consequences that some projects have or may bring. However, in tropical coastal ecosystems, this aspect is not completely acknowledged, studied, or understood. Here, we use tropical seagrass meadows as a model social-ecological system to investigate how sustainable development initiatives result in unintended consequences with both positive and negative outcomes for environment and society. We analyze the initiatives and their effects in terms of a typology encompassing ???flow???, ???addition???, and ???deletion??? effects and investigate them across four types of sustainable development initiatives that occur within tropical coastal environments: (1) megafauna conservation, (2) alternative livelihood programs, (3) mosquito net malaria prophylaxis, and (4) marine protected areas. Using these four initiatives as examples, we show that sustainable development initiatives can produce unintended effects with major consequences. Further, we illustrate how not assessing such effects may ultimately undermine the initial goals of the sustainable development intervention. Our study suggests that acknowledging unintended effects and transitioning them so that they become sustainable is more effective than ignoring effects or viewing them as trade-offs. We strongly stress the need for an a priori process in which positive effects, negative effects, and potential uncertainties and surprises are considered when planning the development intervention, and we argue for greater social-ecological monitoring of initiatives. As such, this contribution links to contemporary approaches dealing with the sustainability of natural resources and social-ecological systems and bridges with the importance of development initiatives in the context of the United Nations Sustainable Development Goals.
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| 11. |
- Jones, Benjamin, 1991-
(author)
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Of seagrass and society : Exploring contributions of tropical seagrass meadows to food security
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Conserving biodiversity while simultaneously feeding a growing population is one of the grand challenges of the Anthropocene. Recently, global assessments have shone a light on the importance of the marine environment for the supply of food (often termed blue food), as well as the diverse and many livelihood opportunities associated to it. Small-scale fisheries (SSF) are essential to this, in which the pursuit of fish and invertebrates are central. If we are to look to blue foods to tackle food insecurity, we need deeper understanding of how coastal habitats function at the nexus of biodiversity, people, and food. Simply put, we need to know how habitats contribute to the supply of food, both in terms of ecological functions and social-economic drivers. Seagrass meadows, diverse and abundant across the Indo-Pacific region, are one of numerous coastal ecosystems that provide food and livelihoods opportunities. Using these systems as a setting, this thesis aims to explore how seagrass meadows and their associated SSF contribute to food security. Comprised of five papers, this thesis relies on a mixed-methods approach to understand seagrass social-ecological systems. The papers range in their dependence on empirical data, their scale as well as the methods employed. Paper I used biodiversity ecosystem function theories to assess the influence of seagrass biota on the production of associated fish in the context of SSF in Tanzania. It highlighted that structural seagrass traits, rather than species richness, are key for driving the abundance and richness of species that are key for food. Paper II investigated the socio-economic drivers that influence seagrass use at the household level. It revealed that household use of seagrass meadows for food and income was higher than all other habitats, and that people use seagrass meadows because they are reliable. It also revealed that household income was key in shaping why people use seagrass meadows as fishing grounds, where both low- and high-income households were dependent on the habitat; low income as a safety-net and high income for high rewards. Paper III examined two key elements of food security, food quantity and quality, and revealed how seagrass meadows contribute to both in the context of micronutrients that are vital for human health. Data from across East Africa showed that seagrass meadows played a more important role than other habitats in providing micronutrient-rich fish species. Paper IV used local ecological knowledge to reveal perceived temporal change in fish and invertebrate abundance and size, but simultaneously identified potential contrasting cognitions that place human communities at risk. Finally, Paper V provided a synthesis of past studies that explored how certain sustainable development initiative result in unintended consequences that influence the supply of blue food. It revealed a number of unintended effects which place the people that use seagrass meadows at risk while at the same time lessening the positive effects of the sustainable development initiative itself. This thesis describes the dynamic interactions between biodiversity, people and food, and place seagrass meadows – habitats that exist globally – at the forefront of the blue food agenda. It highlights how seagrass meadows represent many of the qualities we hope for in a food system – a system that provides sufficient, safe, and nutritious food for multiple and diverse individuals across society.
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| 12. |
- Moreira-Saporiti, Agustín, et al.
(author)
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A trait-based framework for seagrass ecology : Trends and prospects
- 2023
-
In: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 14
-
Research review (peer-reviewed)abstract
- In the last three decades, quantitative approaches that rely on organism traits instead of taxonomy have advanced different fields of ecological research through establishing the mechanistic links between environmental drivers, functional traits, and ecosystem functions. A research subfield where trait-based approaches have been frequently used but poorly synthesized is the ecology of seagrasses; marine angiosperms that colonized the ocean 100M YA and today make up productive yet threatened coastal ecosystems globally. Here, we compiled a comprehensive trait-based response-effect framework (TBF) which builds on previous concepts and ideas, including the use of traits for the study of community assembly processes, from dispersal and response to abiotic and biotic factors, to ecosystem function and service provision. We then apply this framework to the global seagrass literature, using a systematic review to identify the strengths, gaps, and opportunities of the field. Seagrass trait research has mostly focused on the effect of environmental drivers on traits, i.e., “environmental filtering” (72%), whereas links between traits and functions are less common (26.9%). Despite the richness of trait-based data available, concepts related to TBFs are rare in the seagrass literature (15% of studies), including the relative importance of neutral and niche assembly processes, or the influence of trait dominance or complementarity in ecosystem function provision. These knowledge gaps indicate ample potential for further research, highlighting the need to understand the links between the unique traits of seagrasses and the ecosystem services they provide.
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| 13. |
- Nyström, Magnus, et al.
(author)
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Confronting Feedbacks of Degraded Marine Ecosystems
- 2012
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In: Ecosystems. - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 15:5, s. 695-710
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Journal article (peer-reviewed)abstract
- In many coastal areas, marine ecosystems have shifted into contrasting states having reduced ecosystem services (hereafter called degraded). Such degraded ecosystems may be slow to revert to their original state due to new ecological feedbacks that reinforce the degraded state. A better understanding of the way human actions influence the strength and direction of feedbacks, how different feedbacks could interact, and at what scales they operate, may be necessary in some cases for successful management of marine ecosystems. Here we synthesize interactions of critical feedbacks of the degraded states from six globally distinct biomes: coral reefs, kelp forests, seagrass beds, shallow soft sediments, oyster reefs, and coastal pelagic food webs. We explore to what extent current management captures these feedbacks and propose strategies for how and when (that is, windows of opportunity) to influence feedbacks in ways to break the resilience of the degraded ecosystem states. We conclude by proposing some challenges for future research that could improve our understanding of these issues and emphasize that management of degraded marine states will require a broad social-ecological approach to succeed.
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| 14. |
- Olin, Agnes B., et al.
(author)
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Increases of opportunistic species in response to ecosystem change : the case of the Baltic Sea three-spined stickleback
- 2022
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In: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 79:5, s. 1419-1434
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Research review (peer-reviewed)abstract
- Under rapid environmental change, opportunistic species may exhibit dramatic increases in response to the altered conditions, and can in turn have large impacts on the ecosystem. One such species is the three-spined stickleback (Gasterosteus aculeatus), which has shown substantial increases in several aquatic systems in recent decades. Here, we review the population development of the stickleback in the Baltic Sea, a large brackish water ecosystem subject to rapid environmental change. Current evidence points to predatory release being the central driver of the population increases observed in some areas, while both eutrophication and climate change have likely contributed to creating more favourable conditions for the stickleback. The increasing stickleback densities have had profound effects on coastal ecosystem function by impairing the recruitment of piscivorous fish and enhancing the effects of eutrophication through promoting the production of filamentous algae. The increase poses a challenge for both environmental management and fisheries, where a substantial interest from the pelagic fisheries fleet in exploiting the species calls for urgent attention. While significant knowledge gaps remain, we suggest that the case of the Baltic Sea stickleback increase provides generalisable lessons of value for understanding and managing other coastal ecosystems under rapid change.
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| 15. |
- Olin, Agnes B., et al.
(author)
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Predation and spatial connectivity interact to shape ecosystem resilience to an ongoing regime shift
- 2024
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In: Nature Communications. - 2041-1723. ; 15:1
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Journal article (peer-reviewed)abstract
- Ecosystem regime shifts can have severe ecological and economic consequences, making it a top priority to understand how to make systems more resilient. Theory predicts that spatial connectivity and the local environment interact to shape resilience, but empirical studies are scarce. Here, we use >7000 fish samplings from the Baltic Sea coast to test this prediction in an ongoing, spatially propagating shift in dominance from predatory fish to an opportunistic mesopredator, with cascading effects throughout the food web. After controlling for the influence of other drivers (including increasing mesopredator densities), we find that predatory fish habitat connectivity increases resilience to the shift, but only when densities of fish-eating top predators (seals, cormorants) are low. Resilience also increases with temperature, likely through boosted predatory fish growth and recruitment. These findings confirm theoretical predictions that spatial connectivity and the local environment can together shape resilience to regime shifts.
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| 16. |
- van der Heide, T., et al.
(author)
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Ecosystem Engineering by Seagrasses Interacts with Grazing to Shape an Intertidal Landscape
- 2012
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In: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 7:8
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Journal article (peer-reviewed)abstract
- Self-facilitation through ecosystem engineering (i.e., organism modification of the abiotic environment) and consumer-resource interactions are both major determinants of spatial patchiness in ecosystems. However, interactive effects of these two mechanisms on spatial complexity have not been extensively studied. We investigated the mechanisms underlying a spatial mosaic of low-tide exposed hummocks and waterlogged hollows on an intertidal mudflat in the Wadden Sea dominated by the seagrass Zostera noltii. A combination of field measurements, an experiment and a spatially explicit model indicated that the mosaic resulted from localized sediment accretion by seagrass followed by selective waterfowl grazing. Hollows were bare in winter, but were rapidly colonized by seagrass during the growth season. Colonized hollows were heavily grazed by brent geese and widgeon in autumn, converting these patches to a bare state again and disrupting sediment accretion by seagrass. In contrast, hummocks were covered by seagrass throughout the year and were rarely grazed, most likely because the waterfowl were not able to employ their preferred but water requiring feeding strategy ('dabbling') here. Our study exemplifies that interactions between ecosystem engineering by a foundation species (seagrass) and consumption (waterfowl grazing) can increase spatial complexity at the landscape level.
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