| 1. |
- Baden, Susanne Pihl, 1952, et al.
(författare)
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Declining populations of mytilus spp. In north atlantic coastal waters-A swedish perspective
- 2021
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Ingår i: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000. ; 40:2, s. 269-96
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Forskningsöversikt (refereegranskat)abstract
- During the past 2–3 decades, the spatiotemporal distribution of Mytilus spp. in coastal waters of the North Atlantic has changed considerably. In general, reduced abundances of Mytilus are observed, but there is a great degree of local variation, and some areas are also experiencing recovery after declining events. In this review, hypotheses regarding the causes behind the changes are presented with focus on a Swedish perspective. Excessive exploitation of mussel banks combined with direct and indirect effects of climate change are most probably the main drivers of Mytilus spp. decline in large parts of the North Atlantic. On the Swedish west coast, the wild stocks have disappeared despite no overfishing. Paradoxically, they thrive in mussel farms and on other non-demersal substrates. Changes in predation from, for example, increased wintering populations of eiders (Somateria molissima; 10-fold) and green crabs (Carcinus maenas; 3-fold), alteration of natural substrates elicited by eutrophica- tion, and exacerbated by climate change (increased sea surface temperature, precipitation and extreme weather events) are most likely the key factors for the decline. Most anthropogenic stressors may not be decisive by themselves, but combined effects can potentially be fatal to Mytilus spp. adults and larvae.
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| 2. |
- Baden, Susanne P., 1952, et al.
(författare)
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Effects of depth and overgrowth of ephemeral macroalgae on a remote subtidal NE Atlantic eelgrass (Zostera marina) community
- 2022
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X. ; 177
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Tidskriftsartikel (refereegranskat)abstract
- We conducted a short-term field sampling complemented with time integrating stable isotope analysis to ho- listically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifauna and a food web with thornback ray (Raja clavata) as intermediate and cod (Gadus morhua) as top predator. We observed no variation with increasing depth (3.5–11 m) except for decreasing shoot density and biomass of Zostera and macroalgae. Our results indicate that the Finnøya Zostera ecosystem is eutrophicated. During the past three to four decades, nutrients from aquaculture have steadily increased to reach 75% of anthropogenic input while the coastal top predator cod has decreased by 50%. We conclude that bottom-up regulation is a predominant driver of change since top-down regulation is generally weak in low density and exposed Zostera ecosystems such as Finnøya.
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| 3. |
- Gagnon, Karine, et al.
(författare)
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Rapid faunal colonization and recovery of biodiversity and functional diversity following eelgrass restoration
- 2023
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Ingår i: Restoration Ecology. - : Wiley. - 1061-2971 .- 1526-100X. ; 31
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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.
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| 4. |
- Hernroth, Bodil, et al.
(författare)
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Immunosuppression of aquatic organisms exposed to elevated levels of manganese: From global to molecular perspective
- 2020
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Ingår i: Developmental and Comparative Immunology. - : Elsevier BV. - 0145-305X .- 1879-0089. ; 104
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Tidskriftsartikel (refereegranskat)abstract
- Manganese (Mn) is an essential trace metal for all organisms. However, in excess it causes toxic effects but the impact on aquatic environments has so far been highly overlooked. Manganese is abundant both in costal and deep sea sediments and becomes bioavailable (Mn2+) during redox conditions. This is an increasing phenomenon due to eutrophication-induced hypoxia and aggravated through the ongoing climate change. Intracellular accumulation of Mn2+ causes oxidative stress and activates evolutionary conserved pathways inducing apoptosis and cell cycle arrest. Here, studies are compiled on how excess of dissolved Mn suppresses the immune system of various aquatic organisms by adversely affecting both renewal of immunocytes and their functionality, such as phagocytosis and activation of pro-phenoloxidase. These impairments decrease the animal's bacteriostatic capacity, indicating higher susceptibility to infections. Increased distribution of pathogens, which is believed to accompany climate change, requires preserved immune sentinel functions and Mn can be crucial for the outcome of host-pathogen interactions.
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| 5. |
- Kvile, KØ, et al.
(författare)
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Kelp Forest Distribution in the Nordic Region.
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Kelp forests are productive coastal ecosystems that provide a range of ecosystem services. Mapping the distribution and area occupied by kelp forests is a critical step to identify their ecosystem functions and services, including their role in the carbon cycle, and to detect changes in their distribution. We compiled quantitative data of the dominant genera Laminaria and Saccharina across the Nordic region, allowing us to separate kelp forests (areas with dense or moderately dense kelp coverage) from occurrences of single or few individuals. By fitting boosted regression trees to the compiled data, we modelled and predicted the distribution of kelp forests across the Nordic region. Despite the large scale of the analyses, the models captured well the kelps’ environmental affinities and predicted the presence of kelp forests with high accuracy. Dense kelp forests are found along the rocky shores of all the Nordic countries, except in the brackish Baltic Sea, with largest areas in Norway, Greenland and Iceland. The results of this study set the scene for future studies on the importance of kelp forests in the Nordic region, including their contribution to the marine carbon budget.
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| 6. |
- Riera, R, et al.
(författare)
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Severe shifts of Zostera marina epifauna: Comparative study between 1997 and 2018 on the Swedish Skagerrak coast
- 2020
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X. ; 158:111434
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between bottom-up and top-down processes in coastal ecosystems has been scarcely studied so far. Temporal changes in trophic interactions of Zostera marina along the Swedish west coast are relatively well studied, with the exception of epifaunal communities. Epifauna was used as a model study to explore resource (bottom-up) or predator (top-down) regulated in a vegetated ecosystem. We conducted a 21-year comparative study (1997 and 2018) using epifauna of 19 Zostera marina meadows along the Swedish Skagerrak coast. Large changes were observed in the composition of small (0.2–1 mm) and large (> 1 mm) epifauna. In the small-sized epifauna, the nematode Southernia zosterae and harpacticoids showed an increase of 90% and a decrease of 50% of their abundances, respectively. In the large-sized epifauna, the polychaete Platynereis dumerilii and chironomid larvae were absent in 1997 but thrived in 2018 (> 2000 ind. m−2). Mesoherbivores (Idoteids and gammarids) were locally very abundant in 1997 but disappeared in 2018. An 83% decline of mytilids settling in Zostera marina leaves was observed. Our results showed that epifauna is predominantly top-down regulated. An in- tegrative framework of the study area is outlined to shed light on the causes and consequences of the en- vironmental shifts reported in Zostera meadows from the northern Skagerrak area throughout the last three decades.
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