| 1. |
- de Boer, M. Karin, et al.
(author)
-
Dispersal restricts local biomass but promotes the recovery of metacommunities after temperature stress
- 2014
-
In: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 123:6, s. 762-768
-
Journal article (peer-reviewed)abstract
- Landscape connectivity can increase the capacity of communities to maintain their function when environments change by promoting the immigration of species or populations with adapted traits. However, high immigration may also restrict fine tuning of species compositions to local environmental conditions by homogenizing the community. Here we demonstrate that dispersal generates such a tradeoff between maximizing local biomass and the capacity of model periphyton metacommunities to recover after a simulated heat wave. In non-disturbed metacommunities, dispersal decreased the total biomass by preventing differentiation in species composition between the local patches making up the metacommunity. On the contrary, in metacommunities exposed to a realistic summer heat wave, dispersal promoted recovery by increasing the biomass of heat tolerant species in all local patches. Thus, the heat wave reorganized the species composition of the metacommunities and after an initial decrease in total biomass by 38.7%, dispersal fueled a full recovery of biomass in the restructured metacommunities. Although dispersal may decrease equilibrium biomass, our results highlight that connectivity is a key requirement for the response diversity that allows ecological communities to adapt to climate change through species sorting.
|
|
| 2. |
- Donadi, Serena, et al.
(author)
-
Density-dependent positive feedbacks buffer aquatic plants from interactive effects of eutrophication and predator loss
- 2018
-
In: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 99:11, s. 2515-2524
-
Journal article (peer-reviewed)abstract
- Self-facilitation allows populations to persist under disturbance by ameliorating experienced stress. In coastal ecosystems, eutrophication and declines of large predatory fish are two common disturbances that can synergistically impact habitat-forming plants by benefitting ephemeral algae. In theory, density-dependent intraspecific plant facilitation could weaken such effects by ameliorating the amount of experienced stress. Here, we tested whether and how shoot density of a common aquatic plant (Myriophyllum spicatum) alters the response of individual plants to eutrophication and exclusion of large predatory fish, using a 12-week cage experiment in the field. Results showed that high plant density benefitted individual plant performance, but only when the two stressors were combined. Epiphytic algal biomass per plant more than doubled in cages that excluded large predatory fish, indicative of a trophic cascade. Moreover, in this treatment, individual shoot biomass, as well as number of branches, increased with density when nutrients were added, but decreased with density at ambient nutrient levels. In contrast, in open cages that large predatory fish could access, epiphytic algal biomass was low and individual plant biomass and number of branches were unaffected by plant density and eutrophication. Plant performance generally decreased under fertilization, suggesting stressful conditions. Together, these results suggest that intraspecific plant facilitation occurred only when large fish exclusion (causing high epiphyte load) was accompanied by fertilization, and that intraspecific competition instead prevailed when no nutrients were added. As coastal ecosystems are increasingly exposed to multiple and often interacting stressors such as eutrophication and declines of large predatory fish, maintaining high plant density is important for ecosystem-based management.
|
|
| 3. |
- Donadi, Serena, et al.
(author)
-
The body-size structure of macrobenthos changes predictably along gradients of hydrodynamic stress and organic enrichment
- 2015
-
In: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 162:3, s. 675-685
-
Journal article (peer-reviewed)abstract
- Body size is related to an extensive number of species traits and ecological processes and has therefore been suggested as an effective metric to assess community changes and ecosystem's state. However, the applicability of body size as an ecological indicator in benthic environments has been hindered by the poor knowledge of the factors influencing the size spectra of organisms. By applying biological trait analysis (BTA) and generalized linear models to a species dataset collected in the German Wadden Sea (53A degrees 41'14'' N, 7A degrees 14'19'' E) between 1999 and 2012, we show that the size structure of the macrobenthic community changes predictably along environmental gradients. Specifically, body size increases with increasing current-induced shear stress and sediment organic matter content. In addition, the presence of oyster-mussel reefs in one of the sampling stations enhanced the survival of species belonging to the smallest size categories in habitats with high hydrodynamic energy. This was probably due to the local sheltering effects, which together with biodeposition also increased organic matter in the sediment, likely favoring large deposit feeders as well. Our results suggest that body size can be a useful trait for estimating effects of anthropogenic stressors, such as organic enrichment or alteration of hydrodynamic regime and could therefore be effectively included in current monitoring programs of intertidal macrobenthic communities.
|
|
| 4. |
- Eklöf, Johan, 1978-, et al.
(author)
-
Habitat-Mediated Facilitation and Counteracting Ecosystem Engineering Interactively Influence Ecosystem Responses to Disturbance
- 2011
-
In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203.
-
Journal article (peer-reviewed)abstract
- Recovery of an ecosystem following disturbance can be severely hampered or even shift altogether when a point disturbance exceeds a certain spatial threshold. Such scale-dependent dynamics may be caused by preemptive competition, but may also result from diminished self-facilitation due to weakened ecosystem engineering. Moreover, disturbance can facilitate colonization by engineering species that alter abiotic conditions in ways that exacerbate stress on the original species. Consequently, establishment of such counteracting engineers might reduce the spatial threshold for the disturbance, by effectively slowing recovery and increasing the risk for ecosystem shifts to alternative states. We tested these predictions in an intertidal mudflat characterized by a two-state mosaic of hummocks (humps exposed during low tide) dominated by the sediment-stabilizing seagrass Zostera noltii) and hollows (low-tide waterlogged depressions dominated by the bioturbating lugworm Arenicola marina). In contrast to expectations, seagrass recolonized both natural and experimental clearings via lateral expansion and seemed unaffected by both clearing size and lugworm addition. Near the end of the growth season, however, an additional disturbance (most likely waterfowl grazing and/or strong hydrodynamics) selectively impacted recolonizing seagrass in the largest (1 m2) clearings (regardless of lugworm addition), and in those medium (0.25 m2) clearings where lugworms had been added nearly five months earlier. Further analyses showed that the risk for the disturbance increased with hollow size, with a threshold of 0.24 m2. Hollows of that size were caused by seagrass removal alone in the largest clearings, and by a weaker seagrass removal effect exacerbated by lugworm bioturbation in the medium clearings. Consequently, a sufficiently large disturbance increased the vulnerability of recolonizing seagrass to additional disturbance by weakening seagrass engineering effects (sediment stabilization). Meanwhile, the counteracting ecosystem engineering (lugworm bioturbation) reduced that threshold size. Therefore, scale-dependent interactions between habitat-mediated facilitation, competition and disturbance seem to maintain the spatial two-state mosaic in this ecosystem.
|
|
| 5. |
- Eklöf, Johan S., et al.
(author)
-
A spatial regime shift from predator to prey dominance in a large coastal ecosystem
- 2020
-
In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
-
Journal article (peer-reviewed)abstract
- Regime shifts in ecosystem structure and processes are typically studied from a temporal perspective. Yet, theory predicts that in large ecosystems with environmental gradients, shifts should start locally and gradually spread through space. Here we empirically document a spatially propagating shift in the trophic structure of a large aquatic ecosystem, from dominance of large predatory fish (perch, pike) to the small prey fish, the three-spined stickleback. Fish surveys in 486 shallow bays along the 1200 km western Baltic Sea coast during 1979–2017 show that the shift started in wave-exposed archipelago areas near the open sea, but gradually spread towards the wave-sheltered mainland coast. Ecosystem surveys in 32 bays in 2014 show that stickleback predation on juvenile predators (predator–prey reversal) generates a feedback mechanism that appears to reinforce the shift. In summary, managers must account for spatial heterogeneity and dispersal to better predict, detect and confront regime shifts within large ecosystems.
|
|
| 6. |
- Eklöf, Johan S., 1978-, et al.
(author)
-
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
-
In: Fisheries Research. - : Elsevier BV. - 0165-7836 .- 1872-6763. ; 263
-
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.
|
|
| 7. |
- Engel, Friederike G., et al.
(author)
-
Mussel beds are biological power stations on intertidal flats
- 2017
-
In: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 191, s. 21-27
-
Journal article (peer-reviewed)abstract
- Intertidal flats are highly productive areas that support large numbers of invertebrates, fish, and birds. Benthic diatoms are essential for the function of tidal flats. They fuel the benthic food web by forming a thin photosynthesizing compartment in the top-layer of the sediment that stretches over the vast sediment flats during low tide. However, the abundance and function of the diatom film is not homogenously distributed. Recently, we have realized the importance of bivalve reefs for structuring intertidal ecosystems; by creating structures on the intertidal flats they provide habitat, reduce hydrodynamic stress and modify the surrounding sediment conditions, which promote the abundance of associated organisms. Accordingly, field studies show that high chlorophyll a concentration in the sediment co-vary with the presence of mussel beds. Here we present conclusive evidence by a manipulative experiment that mussels increase the local biomass of benthic microalgae; and relate this to increasing biomass of microalgae as well as productivity of the biofilm across a nearby mussel bed. Our results show that the ecosystem engineering properties of mussel beds transform them into hot spots for primary production on tidal flats, highlighting the importance of biological control of sedimentary systems.
|
|
| 8. |
- Eriksson, Britas Klemens, et al.
(author)
-
Cascading predator control interacts with productivity to determine the trophic level of biomass accumulation in a benthic food web
- 2012
-
In: Ecological research. - : Wiley. - 0912-3814 .- 1440-1703. ; 27:1, s. 203-210
-
Journal article (peer-reviewed)abstract
- Large-scale exploitation of higher trophic levels by humans, together with global-scale nutrient enrichment, highlights the need to explore interactions between predator loss and resource availability. The hypothesis of exploitation ecosystems suggests that top-down and bottom-up control alternate between trophic levels, resulting in a positive relationship between primary production and the abundance of every second trophic level. Specifically, in food webs with three effective trophic levels, primary producers and predators should increase with primary production, while in food webs with two trophic levels, only herbivores should increase. We provided short-term experimental support for these model predictions in a natural benthic community with three effective trophic levels, where the number of algal recruits, but not the biomass of gastropod grazers, increased with algal production. In contrast, when the food web was reduced to two trophic levels by removing larger predators, the number of algal recruits was unchanged while gastropod grazer biomass increased with algal production. Predator removal only affected the consumer-controlled early life-stages of algae, indicating that both the number of trophic levels and the life-stage development of the producer trophic level determine the propagation of trophic cascades in benthic systems. Our results support the hypothesis that predators interact with resource availability to determine food-web structure.
|
|
| 9. |
- Eriksson, Britas Klemens, et al.
(author)
-
Declines in predatory fish promote bloom-forming macroalgae.
- 2009
-
In: Ecological Applications. - 1051-0761 .- 1939-5582. ; 19:8, s. 1975-1988
-
Journal article (peer-reviewed)abstract
- In the Baltic Sea, increased dominance of ephemeral and bloom-forming algae is presently attributed to increased nutrient loads. Simultaneously, coastal predatory fish are in strong decline. Using field data from nine areas covering a 700-km coastline, we examined whether formation of macroalgal blooms could be linked to the composition of the fish community. We then tested whether predator or nutrient availability could explain the field patterns in two small-scale field experiments, by comparing joint effects on algal net production from nutrient enrichment with agricultural fertilizer and exclusion of larger predatory fish with cages. We also manipulated the presence of invertebrate grazers. The abundance of piscivorous fish had a strong negative correlation with the large-scale distribution of bloom-forming macroalgae. Areas with depleted top-predator communities displayed massive increases in their prey, small-bodied fish, and high covers of ephemeral algae. Combining the results from the two experiments showed that excluding larger piscivorous fish: (1) increased the abundance of small-bodied predatory fish; (2) changed the size distribution of the dominating grazers, decreasing the smaller gastropod scrapers; and (3) increased the net production of ephemeral macroalgae. Effects of removing top predators and nutrient enrichment were similar and additive, together increasing the abundance of ephemeral algae many times. Predator effects depended on invertebrate grazers; in the absence of invertebrates there were no significant effects of predator exclusion on algal production. Our results provide strong support for regional declines of larger predatory fish in the Baltic Sea promoting algal production by decreasing invertebrate grazer control. This highlights the importance of trophic interactions for ecosystem responses to eutrophication. The view emerges that to achieve management goals for water quality we need to consider the interplay between top-down and bottom-up processes in future ecosystem management of marine resources.
|
|
| 10. |
- Eriksson, Britas Klemens, et al.
(author)
-
Effects of Altered Offshore Food Webs on Coastal Ecosystems Emphasize the Need for Cross-Ecosystem Management
- 2011
-
In: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:7, s. 786-797
-
Research review (peer-reviewed)abstract
- By mainly targeting larger predatory fish, commercial fisheries have indirectly promoted rapid increases in densities of their prey; smaller predatory fish like sprat, stickleback and gobies. This process, known as mesopredator release, has effectively transformed many marine offshore basins into mesopredator-dominated ecosystems. In this article, we discuss recent indications of trophic cascades on the Atlantic and Baltic coasts of Sweden, where increased abundances of mesopredatory fish are linked to increased nearshore production and biomass of ephemeral algae. Based on synthesis of monitoring data, we suggest that offshore exploitation of larger predatory fish has contributed to the increase in mesopredator fish also along the coasts, with indirect negative effects on important benthic habitats and coastal water quality. The results emphasize the need to rebuild offshore and coastal populations of larger predatory fish to levels where they regain their control over lower trophic levels and important links between offshore and coastal systems are restored.
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
- Eriksson, Britas Klemens, et al.
(author)
-
Habitat segregation of plate phenotypes in a rapidly expanding population of three-spined stickleback
- 2021
-
In: Ecosphere. - : Wiley. - 2150-8925 .- 2150-8925. ; 12:6
-
Journal article (peer-reviewed)abstract
- Declines of large predatory fish due to overexploitation are restructuring food webs across the globe. It is now becoming evident that restoring these altered food webs requires addressing not only ecological processes, but evolutionary ones as well, because human-induced rapid evolution may in turn affect ecological dynamics. We studied the potential for niche differentiation between different plate armor phenotypes in a rapidly expanding population of a small prey fish, the three-spined stickleback (Gasterosteus aculeatus). In the central Baltic Sea, three-spined stickleback abundance has increased dramatically during the past decades. The increase in this typical mesopredator has restructured near-shore food webs, increased filamentous algal blooms, and threatens coastal biodiversity. Time-series data covering 22 years show that the increase coincides with a decline in the number of juvenile perch (Perca fluviatilis), the most abundant predator of stickleback along the coast. We investigated the distribution of different stickleback plate armor phenotypes depending on latitude, environmental conditions, predator and prey abundances, nutrients, and benthic production; and described the stomach content of the stickleback phenotypes using metabarcoding. We found two distinct lateral armor plate phenotypes of stickleback, incompletely and completely plated. The proportion of incompletely plated individuals increased with increasing benthic production and decreasing abundances of adult perch. Metabarcoding showed that the stomach content of the completely plated individuals more often contained invertebrate herbivores (amphipods) than the incompletely plated ones. Since armor plates are defense structures favored by natural selection in the presence of fish predators, the phenotype distribution suggests that a novel low-predation regime favors stickleback with less armor. Our results suggest that morphological differentiation of the three-spined stickleback has the potential to affect food web dynamics and influence the persistence and resilience of the stickleback take-over in the Baltic Sea.
|
|
| 14. |
- Eriksson, Britas Klemens, et al.
(author)
-
Local distribution patterns of macroalgae in relation to environmental variables in the northern Baltic Proper
- 2005
-
In: Estuarine, Coastal and Shelf Science. - London : Academic Press. - 0272-7714 .- 1096-0015. ; 62:1-2, s. 109-117
-
Journal article (peer-reviewed)abstract
- The relationship between macroalgal assemblages and abiotic factors was quantified by gradient analyses in an area where long-term changes in macroalgal depth distributions have previously been documented. Biomass data from 4, 6, 8 and 10 m depth in an area of similar salinity (5) and substrate (rock) in the northern Baltic Proper was constrained by a set of environmental variables defining different aspects of abiotic control of species distributions (sediment cover, effective fetch, clarity index, the curvature and slope of the bottom, and direction of exposure) in multivariate analyses at different scales. Fucus vesiculosus dominated the biomass at 4, 6 and 8 m depth, andFurcellaria lumbricalis at 10 m. The applied models explained 30.7–53.3% of the total variance in community structure, and 49.3–60.9% when analysed separately for each depth. A separate analysis of species depth distributions demonstrated that effective fetch was most strongly related to upper limits of the algal belts, sediment cover to the lower limit and density of the F. vesiculosusbelt, and clarity index to the lower limits of F. vesiculosus, perennial red algae, and of the red algal and Sphacelaria spp. belts. The results show a strong correlation between environmental variables and vegetation structure even on a small, local scale in the northern Baltic Proper, indicating a high suitability of the phytobenthic zone for environmental monitoring. The results add to previous studies that show a strong importance of abiotic factors on large-scale variation in phytobentic community composition in the Baltic Sea.
|
|
| 15. |
|
|
| 16. |
- Eriksson, Britas Klemens, 1971-
(author)
-
Long-term changes in macroalgal vegetation on the Swedish coast : An evaluation of eutrophication effects with special emphasis on increased organic sedimentation
- 2002
-
Doctoral thesis (other academic/artistic)abstract
- In this thesis I examine and evaluate the effects of a documented large-scale eutrophication on macroalgal vegetation on the Swedish coast. During the past century the load of nutrients has increased manifold in the Baltic Sea area, increasing primary production and organic sedimentation significantly. By re-investigating a unique reference material of macroalgal vegetation from the 1940-60s and by conducting new diving studies at the same sites, I showed that long-term trends in macroalgal community composition and species’ distributions are consistent with changes expected from an increased nutrient availability. In the Öregrund archipelago (northern Baltic Sea), I documented a declined depth distribution of the dominant canopy forming alga, Fucus vesiculosus, and an increased abundance of opportunistic ephemeral algae compared to 52-53 years ago. In the Gullmar Fjord area (Skagerrak), trends included increased abundances of functional groups with opportunistic algae, decreased abundances of large perennial algae and a general decline in the depth distribution of the vegetation compared to 36-57 years ago. Sediment removal experiments in the northern Baltic Sea confirmed the hypothesis that sedimentation influences macroalgal community composition. Species depending on short periods of reproduction were clearly favoured by sediment removal, especially F. vesiculosus that seemed limited in depth by the local sediment load. Species with long continuous periods of dispersal by spores and/or fragments (for example the ephemerals Cladophora glomerata, Ceramium tenuicorne and Enteromorpha spp.) were more tolerant to the natural sediment load. In general, sediment removal favoured macroalgal establishment and development, indicating that variation in the natural sediment load is an important constraint for sublittoral rocky-shore macroalgal community development. I conclude by suggesting that the documented long-term changes in macroalgal vegetation on the Swedish coast partly are explained by an increased organic sedimentation in these areas.
|
|
| 17. |
|
|
| 18. |
- Eriksson, Britas Klemens, et al.
(author)
-
Omnivory and grazer functional composition moderate cascading trophic effects in experimental Fucus vesiculosus habitats
- 2011
-
In: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 158:4, s. 747-756
-
Journal article (peer-reviewed)abstract
- We tested the relative strength of direct versus indirect effects of an aquatic omnivore depending on the functional composition of grazers by manipulating the presence of gastropod and amphipod grazers and omnivorous shrimp in outdoor mesocosms. By selectively preying upon amphipods and reducing their abundance by 70-80%, omnivorous shrimp favoured the dominance of gastropods. While gastropods were the main microalgal grazers, amphipods controlled macroalgal biomass in the experiment. However, strong predation on the amphipod by the shrimp had no significant indirect effects on macroalgal biomass, indicating that when amphipod abundances declined, complementary feeding by the omnivore on macroalgae may have suppressed a trophic cascade. Accordingly, in the absence of amphipods, the shrimp grazed significantly on green algae and thereby suppressed the diversity of the macroalgal community. Our experiment demonstrates direct consumer effects by an omnivore on both the grazer and producer trophic levels in an aquatic food web, regulated by prey availability.
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
- Hansen, Joakim P., et al.
(author)
-
Recreational boating degrades vegetation important for fish recruitment
- 2019
-
In: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 48:6, s. 539-551
-
Journal article (peer-reviewed)abstract
- Recreational boating increases globally and associated moorings are often placed in vegetated habitats important for fish recruitment. Meanwhile, assessments of the effects of boating on vegetation, and potential effects on associated fish assemblages are rare. Here, we analysed (i) the effect of small-boat marinas on vegetation structure, and (ii) juvenile fish abundance in relation to vegetation cover in shallow wave-sheltered coastal inlets. We found marinas to have lower vegetation cover and height, and a different species composition, compared to control inlets. This effect became stronger with increasing berth density. Moreover, there was a clear positive relationship between vegetation cover and fish abundance. We conclude that recreational boating and related moorings are associated with reduced cover of aquatic vegetation constituting important habitats for juvenile fish. We therefore recommend that coastal constructions and associated boating should be allocated to more disturbance tolerant environments (e.g. naturally wave-exposed shores), thereby minimizing negative environmental impacts.
|
|
| 22. |
|
|
| 23. |
- Ljunggren, Lars, et al.
(author)
-
Recruitment failure of coastal predatory fish in the Baltic Sea coincident with an offshore ecosystem regime shift
- 2010
-
In: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 67:8, s. 1587-1595
-
Journal article (peer-reviewed)abstract
- The dominant coastal predatory fish in the southwestern Baltic Sea, perch and pike, have decreased markedly in abundance during the past decade. An investigation into their recruitment at 135 coastal sites showed that both species suffered from recruitment failures, mainly in open coastal areas. A detailed study of 15 sites showed that areas with recruitment problems were also notable for mortality of early-stage larvae at the onset of exogenous food-intake. At those sites, zooplankton abundance predicted 83 and 34% of the variation in young of the year perch and pike, respectively, suggesting that the declines were caused by recruitment failure attributable to zooplankton food limitation. Incidences of recruitment failure match in time an offshore trophic cascade that generated massive increases in planktivorous sprat and decreases in zooplankton biomass in the early 1990s. Therefore, sprat biomass explained 53% of the variation in perch recruitment from 1994 to 2007 at an open coastal site, where three-spined stickleback also increased exponentially after 2002. The results indicate that the dramatic change in the offshore ecosystem may have propagated to the coast causing declines of the dominating coastal predators perch and pike followed by an increase in the abundance of small-bodied fish.
|
|
| 24. |
- Macura, Biljana, et al.
(author)
-
Impact of structural habitat modifications in coastal temperate systems on fish recruitment : a systematic review
- 2019
-
In: Environmental Evidence. - : BioMed Central. - 2047-2382. ; 8:1
-
Journal article (peer-reviewed)abstract
- Background: Shallow nearshore marine ecosystems are changing at an increasing rate due to a range of human activities such as urbanisation and commercial development. As a result, an increasing number of structural modifications occur in coastal nursery and spawning habitats of fish. Concomitant to this increase, there have been declines in many coastal fish populations and changes in the composition of fish communities. As requested by Swedish stakeholders, this review aimed to synthesise scientific evidence of the impact on fish recruitment of structural modifications in temperate coastal areas.Methods: We searched for peer-reviewed and grey literature on such impacts in English, Dutch, Danish, Finnish, German, Swedish and Spanish. Searches were performed in bibliographic databases, specialist websites, bibliographies of review articles. We also contacted stakeholder to find relevant literature. Eligible studies included small- and large-scale field studies in marine systems and large lakes (> 10,000 km(2)) in temperate regions of the Northern and Southern Hemispheres. Included replicated comparisons of fish recruitment between altered and unaltered control areas, comparisons before and after an alteration, or both. Relevant outcomes (response variables) included measures of recruitment defined as abundance of juvenile fish in coastal habitats. All fish species were considered. Articles were screened for eligibility by title, abstract and full text. Eligible studies were critically appraised based on their external and internal validity. From each eligible study of sufficient validity, we extracted information on study design, measured outcomes, exposure, type of comparator, effect modifiers and study findings. Study findings were synthesised narratively.Results: We searched for eligible studies in 15 databases, 24 specialist websites, Google Scholar, and bibliographies of 11 review articles. The review finally included 37 studies that were eligible and of sufficient validity to be considered for final synthesis. Most studies (23 of 37) were from the Northern Hemisphere. Studies varied in design, spatial resolution, target fish species, and type of structural habitat change. This high level of variation did not allow for a quantitative synthesis and prevented us from drawing general conclusions on the impact of structures or structural modifications on fish recruitment. In this review we provide a narrative synthesis of the evidence base and classify eligible studies into six categories (based on type of exposure and comparator). The categories are as follows: the impacts on fish recruitment of: (1) artificial structures in coastal areas, (2) structures designed as fish attractors, (3) large scale urban sprawl, (4) 'novel' habitats, (5) habitat loss, and (6) restoration.Conclusions: This review revealed a very limited evidence base for how structural modifications and marine urban sprawl can affect fish recruitment. Thus, there is a substantial mismatch between stakeholder needs and research evidence. Further, the impact and ecological performance of artificial structures depend both on context and species. Clearly, there is a need for more research on the subject, especially on long-term consequences at larger spatial scales.
|
|
| 25. |
- Macura, Biljana, et al.
(author)
-
What is the impact on fish recruitment of anthropogenic physical and structural habitat change in shallow nearshore areas in temperate systems? : A systematic review protocol
- 2016
-
In: Environmental Evidence. - : Springer Science and Business Media LLC. - 2047-2382. ; 5:1
-
Research review (peer-reviewed)abstract
- Background:Shallow nearshore marine ecosystems are changing at an increasing rate due to a range of human activities such as urbanisation and commercial development. The growing numbers of constructions and other physical and structural alterations of the shoreline often take place in nursery and spawning habitats of many fish and other aquatic species. Several coastal fish populations have seen marked declines in abundance and diversity during the past two decades. A systematic review on the topic would clarify if anthropogenic physical and structural changes of near-shore areas have effects on fish recruitment and which these effects are.Methods:The review will examine how various physical and structural anthropogenic changes of nearshore fish habitats affect fish recruitment. Relevant studies include small- and large-scale field studies in marine and brackish systems or large lakes in temperate regions of the Northern and Southern hemispheres. Relevant studies may be based on comparisons between undisturbed and disturbed areas, before and after disturbance, or both. Relevant outcomes include measures of recruitment defined as abundance of juveniles of nearshore fish communities. Searches will be made for peer-reviewed and grey literature in English, Dutch, Danish, Finnish, German, Swedish and Spanish. All fish species and species groups will be considered in this review. Included relevant studies will be subject to a critical appraisal that will assess study validity. From relevant included studies, we will extract information on study characteristics, measured outcomes, exposure, comparators, effect modifiers and critical appraisal. Data synthesis will contain narrative and summary findings of each included study of sufficient quality. Meta-analysis may be possible in cases where studies report similar types of outcomes.
|
|
| 26. |
- Niemi, Niklas, et al.
(author)
-
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.
|
|
| 27. |
- Olin, Agnes B., et al.
(author)
-
Increases of opportunistic species in response to ecosystem change : the case of the Baltic Sea three-spined stickleback
- 2022
-
In: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 79:5, s. 1419-1434
-
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.
|
|
| 28. |
- Olin, Agnes B., et al.
(author)
-
Predation and spatial connectivity interact to shape ecosystem resilience to an ongoing regime shift
- 2024
-
In: Nature Communications. - 2041-1723. ; 15:1
-
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.
|
|
| 29. |
|
|
| 30. |
- Yanos, Casey L., et al.
(author)
-
Predator biomass and vegetation influence the coastal distribution of threespine stickleback morphotypes
- 2021
-
In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 11:18, s. 12485-12496
-
Journal article (peer-reviewed)abstract
- Intraspecific niche differentiation can contribute to population persistence in changing environments. Following declines in large predatory fish, eutrophication, and climate change, there has been a major increase in the abundance of threespine stickleback (Gasterosteus aculeatus) in the Baltic Sea. Two morphotype groups with different levels of body armor-completely plated and incompletely plated-are common in coastal Baltic Sea habitats. The morphotypes are similar in shape, size, and other morphological characteristics and live as one apparently intermixed population. Variation in resource use between the groups could indicate a degree of niche segregation that could aid population persistence in the face of further environmental change. To assess whether morphotypes exhibit niche segregation associated with resource and/or habitat exploitation and predator avoidance, we conducted a field survey of stickleback morphotypes, and biotic and abiotic ecosystem structure, in two habitat types within shallow coastal bays in the Baltic Sea: deeper central waters and shallow near-shore waters. In the deeper waters, the proportion of completely plated stickleback was greater in habitats with greater biomass of two piscivorous fish: perch (Perca fluviatilis) and pike (Esox lucius). In the shallow waters, the proportion of completely plated stickleback was greater in habitats with greater coverage of habitat-forming vegetation. Our results suggest niche segregation between morphotypes, which may contribute to the continued success of stickleback in coastal Baltic Sea habitats.
|
|
| 31. |
- Östman, Örjan, et al.
(author)
-
Top-down control as important as nutrient enrichment for eutrophication effects in North Atlantic coastal ecosystems
- 2016
-
In: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 53:4, s. 1138-1147
-
Research review (peer-reviewed)abstract
- Seagrass and seaweed habitats constitute hotspots for diversity and ecosystem services in coastal ecosystems. These habitats are subject to anthropogenic pressures, of which eutrophication is one major stressor. Eutrophication favours fast-growing ephemeral algae over perennial macroalgae and seagrasses, causing habitat degradation. However, changes in top-down control, caused by, for example, overfishing, may also have negative impacts on such habitats by decreasing grazer control of ephemeral algae. Meanwhile, systematic analyses estimating top-down effects of predator manipulations across a wide range of studies are missing, limiting the potential use of top-down control measures in coastal management. Here, we review the literature on experiments that test top-down and bottom-up controls in seagrass Zostera marina and seaweed Fucus spp. food webs in the North Atlantic. Using meta-analysis and meta-regression, we compare effect sizes of consumer and nutrient manipulations on primary producers, grazers and mesopredators. Presence of mesopredators on average doubled the biomass of ephemeral algae through trophic cascades, mainly mediated via negative effects on amphipods and isopods. Of the grazers, gastropods had twice as strong a negative effect on ephemeral algae as amphipods/isopods, but responded weakly to both predators and fertilization. In accordance with theory, top-down effects became stronger with eutrophication. Across studies, top-down effects on ephemeral algae at all trophic levels are on par with eutrophication effects. However, the few studies manipulating piscivorous fish make estimates of their top-down effects uncertain.Synthesis and applications. Consistently strong top-down effects in coastal ecosystems call for an integrated ecosystem perspective. Management should consider measures to improve stocks of predatory fish and reduce mesopredators for restoration and conservation of essential seagrass and seaweed habitats, thereby increasing the long-term viability of ecosystem services from coastal habitats.
|
|
