| 1. |
- Barcelona, Aina, et al.
(författare)
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The role epiphytes play in particle capture of seagrass canopies
- 2023
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Ingår i: Marine Environmental Research. - 0141-1136 .- 1879-0291. ; 192
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Tidskriftsartikel (refereegranskat)abstract
- Seagrass epiphytic communities act as ecological indicators of the quality status of vegetated coastal environments. This study aims to determine the effect leaf epiphytes has on the sediment capture and distribution from outside sources. Thirteen laboratory experiments were conducted under a wave frequency of 0.5 Hz. Three epiphyte models were attached to a Zostera marina canopy of 100 plants/m2 density. The sediment deposited to the seabed, captured by the epiphytic leaf surface, and remaining in suspension within the canopy were quantified. This study demonstrated that the amount of epiphytes impacts on the sediment stocks. Zostera marina canopies with high epiphytic areas and long effective leaf heights may increase the sediment captured on the epiphyte surfaces. Also, reducing suspended sediment and increasing the deposition to the seabed, therefore enhancing the clarity of the water column. For largest epiphytic areas, a 34.5% increase of captured sediment mass is observed. The sediment trapped on the leaves can be 10 times greater for canopies with the highest epiphytic areas than those without epiphytes. Therefore, both the effective leaf length and the level of epiphytic colonization are found to determine the seagrass canopy ability at distributing sediment.
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| 2. |
- Bender, Anke, et al.
(författare)
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Colonisation of wave power foundations by mobile mega- and macrofauna - a 12 year study
- 2020
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 161
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Tidskriftsartikel (refereegranskat)abstract
- Environmental impacts from wave energy generators on the local mobile mega- and macrofauna community have been investigated in the Lysekil project by Uppsala University. Offshore renewable energy installations provide hard, artificial substrates, and as such, they could act as artificial reefs. Foundations with manufactured holes served as complex habitats and foundations without served as non-complex. In this long-term study, SCUBA surveys of mobile fauna in the years 2007, 2008 and 2016-2019 were analyzed. The results show a distinct reef effect on the foundations with significant greater species richness, total number of individuals, greater values of the Shannon-Wiener biodiversity index, and greater abundance of specific reef fauna. Complex foundations accommodated a greater abundance of brown crabs than non-complex foundations, other taxa did not show differences between the two foundation types. A successional increase of species richness, numbers of individuals and Shannon-Wiener biodiversity could be revealed from the first to the second survey period. Inter-annual variation was visible throughout all taxa and years.
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| 3. |
- Bonaglia, Stefano, et al.
(författare)
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Meiofauna improve oxygenation and accelerate sulfide removal in the seasonally hypoxic seabed
- 2020
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 159
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen depleted areas are widespread in the marine realm. Unlike macrofauna, meiofauna are abundant in hypoxic sediments. We studied to what extent meiofauna affect oxygen availability, sulfide removal and microbial communities. Meiofauna were extracted alive and added to intact sediments simulating abundance gradients previously reported in the area. A total of 324 porewater microprofiles were recorded over a 3-week incubation period and microbial community structure and cable bacteria densities were determined at the end of the experiment. At high abundances meiofauna activity deepened oxygen penetration by 85%, 59%, and 62% after 5, 14, and 22 days, respectively, compared to control sediment with scarce meiofauna. After 6 days, meiofauna increased the volume of oxidized, sulfide-free sediment by 68% and reduced sulfide fluxes from 8.8 to 0.4 mmol m(-2) d(-1). After 15 days, the difference with the control attenuated due to the presence of a cable bacteria population, which facilitated sulfides oxidation in all treatments. 16S rRNA gene analysis revealed that meiofauna affected microbial community structure (beta diversity). Thus, meiofauna bioturbation plays an important role in deepening oxygen penetration, counteracting euxinia and in structuring microbial diversity of hypoxic sediments. Co-existence with cable bacteria demonstrates neutralism interaction between these two ecosystem engineers.
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| 4. |
- Dahl, Martin, 1984-, et al.
(författare)
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Impacts of land-use change and urban development on carbon sequestration in tropical seagrass meadow sediments
- 2022
-
Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- Seagrass meadows store significant carbon stocks at a global scale, but land-use change and other anthropogenic activities can alter the natural process of organic carbon (Corg) accumulation. Here, we assessed the carbon accumulation history of two seagrass meadows in Zanzibar (Tanzania) that have experienced different degrees of disturbance. The meadow at Stone Town has been highly exposed to urban development during the 20th century, while the Mbweni meadow is located in an area with relatively low impacts but historical clearing of adjacent mangroves. The results showed that the two sites had similar sedimentary Corg accumulation rates (22–25 g m−2 yr−1) since the 1940s, while during the last two decades (∼1998 until 2018) they exhibited 24–30% higher accumulation of Corg, which was linked to shifts in Corg sources. The increase in the δ13C isotopic signature of sedimentary Corg (towards a higher seagrass contribution) at the Stone Town site since 1998 points to improved seagrass meadow conditions and Corg accumulation capacity of the meadow after the relocation of a major sewage outlet in the mid–1990s. In contrast, the decrease in the δ13C signatures of sedimentary Corg in the Mbweni meadow since the early 2010s was likely linked to increased Corg run-off of mangrove/terrestrial material following mangrove deforestation. This study exemplifies two different pathways by which land-based human activities can alter the carbon storage capacity of seagrass meadows (i.e. sewage waste management and mangrove deforestation) and showcases opportunities for management of vegetated coastal Corg sinks.
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| 5. |
- Islam, Naimul, et al.
(författare)
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Perfluorooctane sulfonic acid (PFOS) adsorbed to polyethylene microplastics : Accumulation and ecotoxicological effects in the clam Scrobicularia plana
- 2021
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Ingår i: Marine Environmental Research. - : Elsevier. - 0141-1136 .- 1879-0291. ; 164
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Tidskriftsartikel (refereegranskat)abstract
- Microplastics are widespread in the marine environment, whereby the uptake of these tiny particles by organisms, can cause adverse biological responses. Plastic debris also act as a vector of many contaminants, herein depending on type, size, shape and chemical properties, possibly intensifying their effects on marine organisms. This study aimed to assess the accumulation and potential toxicity of different sizes of microplastics with and without adsorbed perfluorooctane sulfonic acid (PFOS) in the clam Scrobicularia plana. Clams were exposed to low-density polyethylene microplastics (1 mg L-1) of two different sizes (4-6 and 20-25 μm) virgin and contaminated with PFOS (55.7 ± 5.3 and 46.1 ± 2.9 μg g-1 respectively) over 14 days. Microplastic ingestion, PFOS accumulation and filtration rate were determined along with a multi biomarker approach to assess the biological effects of microplastics ingestion. Biomarkers include oxidative stress (superoxide dismutase, catalase, glutathione peroxidases), biotransformation enzymes (glutathione-S-transferases activity), neurotoxicity (acetylcholinesterase activity), oxidative damage and apoptosis. Microplastics ingestion and PFOS accumulation was microplastic size dependent but not PFOS dependent and filtration rate was reduced at the end of the exposure. Reactive oxygen species in gills and digestive gland were generated as a result of exposure to both types of microplastics, confirming the disturbance of the antioxidant system. Larger virgin microparticles lead to stronger impacts, when compared to smaller ones which was also supported by the Integrated Biomarker Responses index calculated for both tissues. An anti-apoptotic response was detected in digestive glands under exposure to any of the MPs treatments.
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| 6. |
- Kahma, T., et al.
(författare)
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Food-web comparisons between two shallow vegetated habitat types in the Baltic Sea
- 2021
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 169
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Tidskriftsartikel (refereegranskat)abstract
- Coastal vegetated habitats maintain highly diverse communities, where the contribution of macrophyte production is significant for macroinvertebrate primary consumers. In the brackish-waters of the Baltic Sea, the taxonomical diversity of different macrophytes includes both marine and limnic species. To study the basal food-web differences of two key vegetated habitat types, either dominated by a perennial brown macroalgae (Fucus vesiculosus) or by angiosperm plants, 13C and 15N compositions of different primary producers and macroinvertebrate consumers were examined, and their diets were estimated by Bayesian mixing models. Carbon isotope diversity of primary producers was high especially in the hard-bottom Fucus-dominated habitats, which was also reflected in a larger consumer isotope niche. However, consumer isotope niche among sites was similar within the same habitat type. Our models indicated that the perennial macrophyte dietary median contribution was about 25% for deposit feeders and omnivores in both habitat types, while epigrazers preferred filamentous algae (30–60%). The niche positions of the abundant clams L. balthica, M. arenaria and C. glaucum differed between the two habitats, but they showed only small (<10% units) differences in their macrophyte dietary contributions. The isotopic compositions of the dominating primary producer assemblage reflected significantly in the isotope niche structure of the associated primary consumers.
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| 7. |
- Kahma, T. I., et al.
(författare)
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Macroalgae fuels coastal soft-sediment macrofauna : A triple-isotope approach across spatial scales
- 2020
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 162
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Tidskriftsartikel (refereegranskat)abstract
- Shallow coastal zones may provide cross-habitat nutrient subsidies for benthic communities offshore, as macrophyte matter can drift to deeper sediments. To study the relative importance of carbon and nutrient flows derived from different primary food sources in a coastal ecosystem, the diets of clam Macoma balthica, polychaete Marenzelleria spp. and mussel Mytilus trossulus were examined across environmental gradients in the northern Baltic Sea using a triple-isotope approach (i.e. 13C, 15N and 34S) and Bayesian mixing models (MixSIAR). Our results suggest that in shallow habitats, production from Fucus vesiculosus is the primary energy source for M. balthica. The proportion of macroalgae-derived matter in the diet of M. balthica and Marenzelleria spp. decreased following a depth gradient. Our models for M. trossulus indicate that the pelagic POM dominates its diet. Our results indicate a trophic connectivity between shallow macrophyte-dominated and deeper habitats, which receive significant amounts of nutrient subsidies from shallower areas.
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| 8. |
- Karametsidis, Georgios, et al.
(författare)
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The trade-off between condition and growth shapes juveniles' survival of harvested demersal fish of the Mediterranean sea
- 2023
-
Ingår i: Marine Environmental Research. - : Elsevier. - 0141-1136 .- 1879-0291. ; 184
-
Tidskriftsartikel (refereegranskat)abstract
- Fish body condition and growth are two interrelated traits closely associated with species life history and fitness, whose trade-off can ultimately impact population dynamics albeit seldom empirically demonstrated. They can intricately affect survival rates, which are particularly relevant for species under exploitation. Using individual spatiotemporal information in Northwestern Mediterranean, we document for the first time the existence of a trade-off between condition and growth in regulating survival dynamics in two important fish species for the Mediterranean fisheries that are characterized by contrasting life histories. For the European hake (Merluccius merluccius), a benthopelagic species, juveniles' body condition was detected to be positively linked to survival and negatively associated with the growth of this age group. For the red mullet (Mullus barbatus), the same pattern was observed for young adults. We also show that the observed patterns on a regional level have a clear spatial dependence as we found that observed body condition over a local scale had a broad effect on the population dynamics of the whole region, with the Ebro delta area emerging as the demographic engine of the two species. We discuss our results in the context of fisheries management and underline the importance of improving current stock assessment models and spatially based fishery management towards incorporating body condition and growth due to their influence on important parameters such as survival.
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| 9. |
- Kolzenburg, Regina, et al.
(författare)
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Structural integrity and skeletal trace elements in intertidal coralline algae across the Northeast Atlantic reveal a distinct separation of the leading and the trailing edge populations
- 2023
-
Ingår i: Marine Environmental Research. - : Elsevier. - 0141-1136 .- 1879-0291. ; 190
-
Tidskriftsartikel (refereegranskat)abstract
- Intertidal macroalgae, such as coralline algae, represent an essential structural element and substrate in rocky coastal zones. They have a high degree of flexibility allowing their survival in environments with severe mechanical stress during tidal cycles. This study characterised the genicula and intergenicula of the calcifying red algae Corallina officinalis across its geographic distribution in the Northeast Atlantic. Poleward populations have constructed more sturdy cell walls compared to equatorward populations, potentially due to greater local adaptations to higher frequency and intensity of environmental factors like storms and wave action. Southern populations showed a lack of local adaptation culminating in survival rather than thriving within their current environment, hence, they are located at the margin of this species' favourable conditions. Results clarify significant differences between latitudes and indicate a north-to-south gradient in this species’ skeletal elemental composition. Northern populations were dominated by cadmium, whereas chromium was the major trace element found in southern populations. In the future, these characteristics could lead to a permanent decline and a decrease in the ecosystem functions of C. officinalis in the southern locations in the Northeast Atlantic, which may be accelerated by predicted future climatic changes.
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| 10. |
- Kuprijanov, Ivan, et al.
(författare)
-
A case study on microlitter and chemical contaminants : Assessing biological effects in the southern coast of the Gulf of Finland (Baltic sea) using the mussel Mytilus trossulus as a bioindicator
- 2024
-
Ingår i: Marine Environmental Research. - : Elsevier. - 0141-1136 .- 1879-0291. ; 199
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Tidskriftsartikel (refereegranskat)abstract
- Chemical and microlitter (ML) pollution in three Estonian coastal areas (Baltic Sea) was investigated using mussels (Mytilus trossulus). Polycyclic aromatic hydrocarbons (PAH) in mussel tissues were observed in moderate levels with high bioaccumulation factors for the more hydrophilic and low molecular weight PAH (LMW PAH), namely anthracene and fluorene. Tissue concentrations of polybrominated diphenyl ethers (PBDE) and cadmium within mussel populations exceeded the Good Environmental Status thresholds by more than 200% and 60%, respectively. Multiple contamination at the Muuga Harbour site by tributyltin, high molecular weight PAH, including the highly toxic benzo[c]fluorene and PBDE, coincided with the inhibition of acetylcholinesterase activity and a lower condition index of the mussels. The metabolization and removal of bioaccumulated LMW PAH, reflected in the dominance of oxy-PAH such as anthracene-9,10-dione, is likely associated with the increased activity of glutathione S-transferase in caged mussels. Only a few microplastic particles were observed among the ML in mussel tissues, with coloured cellulose-based microfibers being the most prevalent. The average concentration of ML in mussels was significantly higher at the harbour area than at other sites. The integrated biomarker response index values allowed for the differentiation of pollution levels across studied locations representing high, intermediate, and low pollution levels within the studied area.
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| 11. |
- Källberg Normark, Lydia, et al.
(författare)
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Isotopic niche size variability in an ecosystem engineer along a disturbance gradient in a South African lagoon
- 2022
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 173
-
Tidskriftsartikel (refereegranskat)abstract
- A key challenge for natural resource management is how to detect effects of environmental stress on individuals and populations before declines in abundance occur. Variability in carbon and nitrogen isotope composition (δ13C and δ15N) among consumers can provide information on the population trophic niche and how it may change in response to environmental stress. We measured δ13C and δ15N values in primary producers and in an ecosystem engineer, the bioturbating sandprawn Kraussillichirus kraussi, in Langebaan Lagoon, South Africa, along a human disturbance gradient. Diet partitioning mixing models were coupled with isotope niche analyses and individual body condition data to investigate shifts in resource utilisation and diet plasticity from minimally to highly disturbed sites. The δ15N values of seagrass, Zostera capensis indicated a nutrient gradient, with the highest δ15N values at highly disturbed sites indicating either anthropogenic or marine nitrogen inputs. A decreasing δ15N signal with distance from human disturbance/mouth of lagoon was however not evident for sandprawns nor their presumed dietary sources (phytoplankton, microphytobenthos or sediment organic matter), likely because of faster isotope turnover time compared to seagrass and/or differential fractionation for sandprawns among the sites. Sandprawn isotope niche sizes varied among sites, with no trend along the disturbance gradient. The smallest niche coincided with uniform feeding on microphytobenthos according to mixing models. On an individual level, deviating isotope values from population means were correlated to better body condition, suggesting that a divergent feeding strategy is beneficial. Our results support a generalist feeding behavior of the sandprawns with no evidence of reduced physiological status at the site with most human disturbance.
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| 12. |
- Morys, Claudia, et al.
(författare)
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Impacts of bottom trawling on benthic biogeochemistry in muddy sediments : Removal of surface sediment using an experimental field study
- 2021
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 169
-
Tidskriftsartikel (refereegranskat)abstract
- Experimental benthic dredging was conducted in an unfished, muddy area in the Baltic Proper to mimic the impact of trawling by removing surface sediment, with a focus on benthic biogeochemical processes. Sediment cores were taken on the track and compared to undisturbed controls. Benthic fluxes were immediately affected and an upward shift in pore water DIC profiles was detected. The time needed for the sediment to readjust to a new biogeochemical state seemed to be nutrient-specific. Sediment properties (profiles of chlorophyll, organic carbon and water content) were found to change significantly. Macrofauna was removed completely by the dredge pointing out the potential loss of highly valuable functions that are associated with them. In the Baltic Sea, in areas which were previously the most heavily fished, the frequency of trawling may have left little time for readjustment and potentially kept the seabed in a permanent state of transient biogeochemical cycling.
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| 13. |
- Ragazzola, Federica, et al.
(författare)
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An intertidal life : Combined effects of acidification and winter heatwaves on a coralline alga (Ellisolandia elongata) and its associated invertebrate community
- 2021
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Ingår i: Marine Environmental Research. - : Elsevier. - 0141-1136 .- 1879-0291. ; 169
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Tidskriftsartikel (refereegranskat)abstract
- In coastal marine ecosystems coralline algae often create biogenic reefs. These calcareous algal reefs affect their associated invertebrate communities via diurnal oscillations in photosynthesis, respiration and calcification processes. Little is known about how these biogenic reefs function and how they will be affected by climate change. We investigated the winter response of a Mediterranean intertidal biogenic reef, Ellissolandia elongata exposed in the laboratory to reduced pH conditions (i.e. ambient pH – 0.3, RCP 8.5) together with an extreme heatwave event (+1.4 °C for 15 days). Response variables considered both the algal physiology (calcification and photosynthetic rates) and community structure of the associated invertebrates (at taxonomic and functional level). The combination of a reduced pH with a heatwave event caused Ellisolandia elongata to significantly increase photosynthetic activity. The high variability of calcification that occurred during simulated night time conditions, indicates that there is not a simple, linear relationship between these two and may indicate that it will be resilient to future conditions of climate change.In contrast, the associated fauna were particularly negatively affected by the heatwave event, which impoverished the communities as opportunistic taxa became dominant. Local increases in oxygen and pH driven by the algae can buffer the microhabitat in the algal fronds, thus favouring the survival of small invertebrates.
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| 14. |
- Rodil, Iván F., et al.
(författare)
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Variable contributions of seafloor communities to ecosystem metabolism across a gradient of habitat-forming species
- 2021
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 167
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Tidskriftsartikel (refereegranskat)abstract
- The contributions of habitat-forming species to the biodiversity and ecosystem processes of marine and terrestrial ecosystems are widely recognized. Aquatic plants are considered foundation species in shallow ecosystems, as they maintain biodiversity and sustain many ecosystem functions such as primary production and respiration. Despite the increasing amount of biodiversity-ecosystem functioning experiments in seagrass habitats, the effects of benthic variability on ecosystem functioning are rarely investigated across spatially variable aquatic plant habitats. Here, we quantitatively link seasonal variability in seafloor metabolism (i.e. gross primary production and community respiration) with major benthic community components (i.e. microphytobenthos, aquatic plants and macrofauna) across a structural complexity gradient of habitat-forming species (in terms of shoot density and biomass), ranging from bare sand, to a sparse mixture of plants to a dense monospecific seagrass meadow. The increasing complexity gradient enhanced the magnitude of the relationships between benthic community and seafloor metabolism. The daily average seafloor metabolism per season at the bare site was similar to the sparse site, highlighting the role of microphytobenthos for seafloor metabolism in shallow unvegetated sediments. The contribution of the associated macrofauna to the seafloor respiration was similar to the aquatic plant community contribution. Infauna was the main macrofaunal component significantly explaining the seasonal variability of seafloor respiration. However, benthic community-metabolism relationships were stronger within the plant community than within the macrofauna community (i.e. steepest slopes and lowest p-values). Understanding these relationships are a priority since climate change and biodiversity loss are reducing habitat complexity around the world, jeopardizing valuable ecosystem functions and services.
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| 15. |
- Rugiu, Luca, et al.
(författare)
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Climate change driven hyposalinity as a selective agent in the littoral mesoherbivore Idotea balthica
- 2021
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 163
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 Elsevier Ltd Climate change will include a decrease in seawater salinity in the Baltic Sea. We quantified the effects of the projected future desalination on survival of the early life stage of the littoral herbivore Idotea balthica. We collected egg-bearing Idotea from three range-margin Baltic Sea populations, we exposed half of each brood to either current (6‰) or future salinity (3.5‰). We genotyped a subsample of each brood to analyse patterns of allelic change and to identify genomic regions targeted by selection. The survival was overall reduced by hyposalinity and broods varied in response to hyposalinity implying genetic variation in tolerance, with a stronger decrease in genetic diversity in future salinity. Finally, we identified proteins with crucial roles in basic cellular functions. This study indicates that projected future northern Baltic Sea hyposalinity will not just hamper I. balthica survival, but its selective pressure may also affect genetic diversity and cell physiology.
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| 16. |
- Ruiz, Micaela B., et al.
(författare)
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Molecular responses of a key Antarctic species to sedimentation due to rapid climate change
- 2022
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- Rapid regional warming causing glacial retreat and melting of ice caps in Antarctica leads benthic filter-feeders to be exposed to periods of food shortage and high respiratory impairment as a consequence of seasonal sediment discharge in the West Antarctic Peninsula coastal areas. The molecular physiological response and its fine-tuning allow species to survive acute environmental stress and are thus a prerequisite to longer-term adaptation to changing environments. Under experimental conditions, we analyzed here the metabolic response to changes in suspended sediment concentrations, through transcriptome sequencing and enzymatic measurements in a highly abundant Antarctic ascidian. We found that the mechanisms underlying short-term response to sedimentation in Cnemidocarpa verrucosa sp. A involved apoptosis, immune defense, and general metabolic depression. These mechanisms may be understood as an adaptive protection against sedimentation caused by glacial retreat. This process can strongly contribute to the structuring of future benthic filter-feeder communities in the face of climate change.
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| 17. |
- van der Schyff, Veronica, et al.
(författare)
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Impacts of a shallow shipwreck on a coral reef: A case study from St. Brandon’s Atoll, Mauritius, Indian Ocean.
- 2020
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 156
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Tidskriftsartikel (refereegranskat)abstract
- Shallow shipwrecks can have severe ecological and toxicological impacts on coral atolls. In 2012, a tuna longliner ran aground on the reef crest of St Brandon’s Atoll, Mauritius, broke up into three pieces which was moved by currents and storms into the lagoon. In the months following the grounding, the coral around the wreck became dead and black. Down-current from the wreck, a dense bloom of filamentous algae (Ulva sp.) attached to coral occurred. To determine the ecological effects of the wreck on the system, the marine biota around the wreck, in the algal bloom, and fish reference zones were counted in 2014. Metal concentrations in reference and affected coral was determined using inductively coupled plasma mass spectrometry (ICP/MS). A pronounced difference was seen in the metal concentration pattern between coral from the wreck- and algal zones, and the coral reference zone. While the wreck zone contained the highest abundance of fish, the fish reference zone had the highest species diversity but with fewer fish. We also counted eleven Critically Endangered hawksbill sea turtles Eretmochelys imbricata and significantly more sea cucumbers in the algal zone than the reference zones. The effects of shipwrecks on coral reefs must be considered a threat over periods of years and should be studied further.
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| 18. |
- Ytrehus, Björnar
(författare)
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Seabird beachcast events associated with bycatch in the Norwegian purse seine fishery
- 2022
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 177
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Tidskriftsartikel (refereegranskat)abstract
- Beachcast events, where a large number of seabird carcasses drift ashore, occur with irregular intervals. These events are due to specific situations where mass mortality of seabirds have occurred. Disentangling the cause of these events can provide valuable information on stressors impacting seabird populations. Following several mass mortality events involving gulls in northern Norway, an investigation of the probable cause of death was initiated. In total 75 dead gulls were collected at two occasions and necropsies were carried out. The findings from the necropsy of the gulls were consistent with drowning as the primary cause of death. Bycatch in coastal purse seine fishery was considered a potential cause of the mortality and monitoring of seabird bycatch in this fishery was thus initiated. The monitoring of fishing operations revealed that 10% of 91 fishing events observed led to bycatch, with a total of 32 bycaught seabirds. These bycatch events resulted in a total estimated bycatch rate of 0.356 (95% CI = 0.133-0.949) birds per haul. These findings are consistent with the hypothesis that the registered mortality events were caused by bycatch in the purse seine fishery. The highly episodic and unpredictable nature of these events makes it demanding to achieve solid estimates of the occurrence and extent of bycatch without a very high monitoring effort. Our study shows that systematic investigation following beachcast events can shed light on the occurrence of such extreme events.
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| 19. |
- Maia, S., et al.
(författare)
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Effects of ocean acidification and warming on the development and biochemical responses of juvenile shrimp Palaemon elegans (Rathke, 1837)
- 2022
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic CO2 emissions have led to the warming and acidification of the oceans. Although, there is a growing of evidence showing that simultaneous occurrence of ocean acidification and ocean warming are threats to marine organisms, information on their combined effect on coastal shrimp species remains scarce. The purpose of this study was to estimate the combined effects of seawater acidification and warming on growth-related traits and biochemical responses of P. elegans juveniles. In this work, shrimp were exposed for 65 days at 4 experimental conditions: pH 8.10 * 18 °C, pH 7.80 * 18 °C, pH 8.10 * 22 °C, pH 7.80 * 22 °C. The results showed that low pH decreases the lipid content by ∼13% (p < 0.05). Higher temperature reduced the condition factor by ∼11%, the protein content by ∼20%, the PUFA by ∼8,6% and shortened moulting events by 5 days (p > 0.05) while the SFA increased ∼9.4%. The decrease in condition factor and protein was however more prominent in organisms exposed to the combination of pH and temperature with a decrease of ∼13% and ∼21%, respectively. Furthermore, essential fatty acids as EPA and DHA also decreased by ∼20% and ∼6.6% in low pH and higher temperature condition. Despite this study suggest that warming may have a greater impact than acidification, it has been shown that their combined effect can exacerbate these impacts with consequences for the shrimp's body size and biochemical profile. © 2022
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| 20. |
- Mohseni, Farzane, et al.
(författare)
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Ocean water quality monitoring using remote sensing techniques: A review
- 2022
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- Ocean Water Quality (OWQ) monitoring provides insights into the quality of water in marine and near-shore environments. OWQ measurements can contain the physical, chemical, and biological characteristics of oceanic waters, where low OWQ values indicate an unhealthy ecosystem. Many parameters of water can be estimated from Remote Sensing (RS) data. Thus, RS offers significant opportunities for monitoring water quality in estuaries, coastal waterways, and the ocean. This paper reviews various RS systems and techniques for OWQ monitoring. It first introduces the common OWQ parameters, followed by the definition of the parameters and techniques of OWQ monitoring with RS techniques. In this study, the following OWQ parameters were reviewed: chlorophyll-a, colored dissolved organic matter, turbidity or total suspended matter/solid, dissolved organic carbon, Secchi disk depth, suspended sediment concentration, and sea surface temperature. This study presents a systematic analysis of the capabilities and types of spaceborne systems (e.g., optical and thermal sensors, passive microwave radiometers, active microwave scatterometers, and altimeters) which are commonly applied to OWQ assessment. The paper also provides a summary of the opportunities and limitations of RS data for spatial and temporal estimation of OWQ. Overall, it was observed that chlorophyll-a and colored dissolved organic matter are the dominant parameters applied to OWQ monitoring. It was also concluded that the data from optical and passive microwave sensors could effectively be applied to estimate OWQ parameters. From a methodological perspective, semi-empirical algorithms generally outperform the other empirical, analytical, and semi-analytical methods for OWQ monitoring.
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| 21. |
- Polovodova Asteman, Irina, 1980, et al.
(författare)
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Recent environmental change in the Kosterhavet National Park marine protected area as reflected by hydrography and sediment proxy data.
- 2021
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136. ; 166
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Tidskriftsartikel (refereegranskat)abstract
- The Koster Trench is the deepest part of the Kosterfjord (Skagerrak, North Sea), which stretches southward along the west coast of Sweden. Since 2009 Kosterfjord has been included in the Marine Protected Area Kosterhavet National Park. To effectively manage national parks, long-term time series of ecological data are needed and those can be derived from local sediment archives. In this study we present multiproxy geochemical (bulk TOC, C/N and heavy metals) and micropaleontological (dinoflagellate cysts, selected palynomorphs and benthic foraminifera) data from a sediment core taken in the southern part of the Koster Trench. Radiometric dating by 210Pb and 137Cs shows that the core archived the environmental changes that took place between 1988 and 2012. The TOC, heavy metals and foraminiferal indices indicate mainly high to good ecological quality status, with moderate ecological quality for arsenic concentrations. Dinoflagellate cysts suggest a major change occurring in the upper water column around 2002. The cysts of Pentapharsodinium dalei peak around 1992 and show overall slightly higher relative abundances between 1988 and 2002. Increased abundance of Biecheleria baltica cysts, heterotrophic species, oligotrichids, pollen and spores characterise the upper core part deposited from 2002 to 2012. Also, there is a clear increase of Alexandrium cysts in the top of the core (∼2008 – 2012). Benthic foraminifera show a major faunal change reflected in a significant increase of agglutinated species (mainly Textularia earlandi) from 2007 towards present day, while the lower part of the core (1988-2007) is dominated by calcareous species. Overall, the changes demonstrated by the dataset suggest an increased freshwater input or a higher river/land runoff, as supported by climatic and hydrographical data showing increased precipitation over the study area, decreasing salinity, and an increasing trend in particulate organic carbon in the surface waters. These changes, in combination with trawling activities, which have been moved to the deepest part of the trench since 2009, seem to favour dinoflagellate and benthic foraminiferal species with mixotrophic and omnivorous feeding strategies. Similar to the dinocysts, calculated foram-AMBI and NQIforam indices show a shift around 2002 suggesting that environmental changes occurring in the study area are likely linked to darkening of coastal waters.
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