| 1. |
- Eggertsen, Maria, et al.
(författare)
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Seascape Configuration and Fine-Scale Habitat Complexity Shape Parrotfish Distribution and Function across a Coral Reef Lagoon
- 2020
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Ingår i: Diversity. - : MDPI AG. - 1424-2818. ; 12:10
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Tidskriftsartikel (refereegranskat)abstract
- Structural complexity spanning fine to broad spatial scales can influence the distribution and activity of key organisms within marine ecosystems. However, the relative importance of hard (e.g., corals) and/or soft (e.g., macroalgae) structural complexity for marine organisms is often unclear. This study shows how both broad-scale (seascape configuration of coral structure) and fine-scale habitat complexity (structure height, number of holes, and presence of macroalgae) can influence the abundance and spatial ecology of reef fish. Underwater visual census of fish, surveys of habitats, remote underwater videos, and behavioral observations by following individual fish were used to quantify fine-scale habitat characteristics (e.g., complexity, coral structure height, macroalgae presence) and the abundance, size structure, and behavior (rates of herbivory, tortuosity ratios and total distance travelled) of abundant parrotfish. Both seascape configuration and macroalgae influenced the patterns of fish abundance and rates of herbivory. However, these relationships varied with trophic groups and ontogenetic stages. Abundance of adult and intermediate-phase parrotfishes was positively influenced by densely aggregated coral structures, whereas juvenile abundance was positively influenced by the presence of macroalgae. Foraging path and bite rates of an abundant parrotfish, Chlorurus spilurus, were not influenced by coral structure configuration or height, but the presence of macroalgae increased the bite rates of all juvenile parrotfish. Our results suggest that a combination of seascape configuration, fine-scale habitat complexity, and microhabitat selectivity influence reef fish community structure and foraging behavior, thus altering herbivory. However, these relationships can differ among functional groups of fish and life-history stages. Information on these fish–habitat interactions is critical for identifying habitats that facilitate ecological functions and ensures the successful management and conservation of essential habitats.
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| 2. |
- Eggertsen, Maria, 1981-, et al.
(författare)
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Seascape configuration and microhabitat condition shapes parrotfish distribution and function across a coral reef lagoon
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Structural complexity spanning fine to coarse spatial scales can influence the distribution and activity of key organisms within marine ecosystems. The current study shows how both broad-scale (seascape configuration of coral structure) and fine-scale habitat complexity (structural height, number of holes, and macroalgae) can influence the abundance and spatial ecology of reef fishes in a shallow tropical lagoon. Visual surveys, remote underwater video, and field observations were used to quantify habitat characteristics and the abundance, size structure and behavior (rates of herbivory, tortuosity ratios and total distance travelled) of abundant reef fishes. Both seascape configuration and macroalgae influenced patterns of fish abundance and rates of herbivory. However, these relationships varied with fish trophic groups and ontogenetic stages. High levels of hard complexity increased abundance of adult and intermediate-phase parrotfishes, whereas juvenile abundance was positively influenced by the presence of macroalgae, irrespective of the spatial configuration of coral structure in the seascape. Foraging path patterns (directed vs. convoluted) and bite rates of an abundant excavating parrotfish, Chlorurus spilurus, was not influenced by coral structure configuration in the seascape (dense/sparse) or coral structure height (high/low), but the presence of macroalgae increased the bite rates of all juvenile parrotfishes (including C. spilurus). Our results suggest a combination of microhabitat selectivity, fine-scale habitat complexity, and seascape configuration influence reef fish community structure and foraging behaviour, with consequences for the important ecological function of herbivory.
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| 3. |
- Fulton, Christopher J., et al.
(författare)
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Macroalgal meadow habitats support fish and fisheries in diverse tropical seascapes
- 2020
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 21:4, s. 700-717
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Tidskriftsartikel (refereegranskat)abstract
- Canopy-forming macroalgae can construct extensive meadow habitats in tropical seascapes occupied by fishes that span a diversity of taxa, life-history stages and ecological roles. Our synthesis assessed whether these tropical macroalgal habitats have unique fish assemblages, provide fish nurseries and support local fisheries. We also applied a meta-analysis of independent surveys across 23 tropical reef locations in 11 countries to examine how macroalgal canopy condition is related to the abundance of macroalgal-associated fishes. Over 627 fish species were documented in tropical macroalgal meadows, with 218 of these taxa exhibiting higher local abundance within this habitat (cf. nearby coral reef) during at least one life-history stage. Major overlap (40%-43%) in local fish species richness among macroalgal and seagrass or coral reef habitats suggest macroalgal meadows may provide an important habitat refuge. Moreover, the prominence of juvenile fishes suggests macroalgal meadows facilitate the triphasic life cycle of many fishes occupying diverse tropical seascapes. Correlations between macroalgal canopy structure and juvenile abundance suggests macroalgal habitat condition can influence levels of replenishment in tropical fish populations, including the majority of macroalgal-associated fishes that are targeted by commercial, subsistence or recreational fisheries. While many macroalgal-associated fishery species are of minor commercial value, their local importance for food and livelihood security can be substantial (e.g. up to 60% of landings in Kenyan reef fisheries). Given that macroalgal canopy condition can vary substantially with sea temperature, there is a high likelihood that climate change will impact macroalgal-associated fish and fisheries.
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| 4. |
- Wilson, Shaun K., et al.
(författare)
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The contribution of macroalgae-associated fishes to small-scale tropical reef fisheries
- 2022
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 23:4, s. 847-861
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Tidskriftsartikel (refereegranskat)abstract
- Macroalgae-dominated reefs are a prominent habitat in tropical seascapes that support a diversity of fishes, including fishery target species. To what extent, then, do macroalgal habitats contribute to small-scale tropical reef fisheries? To address this question we: (1) Quantified the macroalgae-associated fish component in catches from 133 small-scale fisheries, (2) Compared life-history traits relevant to fishing (e.g. growth, longevity) in macroalgal and coral-associated fishes, (3) Examined how macroalgae-associated species can influence catch diversity, trophic level and vulnerability and (4) Explored how tropical fisheries change with the expansion of macroalgal habitats using a case study of fishery-independent data for Seychelles. Fish that utilised macroalgal habitats comprise 24% of the catch, but very few fished species relied entirely on macroalgal or coral habitats post-settlement. Macroalgal and coral-associated fishes had similar life-history traits, although vulnerability to fishing declined with increasing contribution of macroalgae association to the catch, whilst mean trophic level and diversity peaked when macroalgal-associated fish accounted for 20%–30% of catches. The Seychelles case study revealed similar total fish biomass on macroalgal and coral reefs, although the biomass of primary target species increased as macroalgae cover expanded. Our findings reinforce that multiple habitat types are needed to support tropical fishery stability and sustainability. Whilst coral habitats have been the focus of tropical fisheries management, we show the potential for macroalgae-associated fish to support catch size and diversity in ways that reduce vulnerability to overfishing. This is pertinent to seascapes where repeated disturbances are facilitating the replacement of coral reef with macroalgal habitats.
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| 5. |
- Berkström, Charlotte, et al.
(författare)
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The arrangement of nurseries within a tropical seascape structure fish communities on nearby reefs
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Ecosystems are linked by the movement of organisms across habitat boundaries and the arrangement of habitat patches can affect species abundance and composition. In tropical seascapes many coral reef fishes settle in adjacent habitats and undergo ontogenetic migrations to coral reefs as they grow. Few studies have attempted to measure at what distances from nursery habitats these fish migrations (connectivity) cease to exist and how the abundance, biomass and proportion of nursery species change on coral reefs along distance gradients away from nursery areas. The present study examines seascape arrangement, including distances between habitats, and its consequences on connectivity within a tropical seascape in Mozambique using a seascape ecology approach. Fish and habitat surveys were undertaken in 2016/2017 and a thematic habitat map was created in ArcGIS, where cover and distances between habitat patches were calculated. Distance to mangroves, seagrasses and channels were significant for most nursery species and both abundance, biomass and proportion of nursery species were highest in the south of the archipelago, where mangroves were present and decreased with distance to nurseries (mangroves and seagrasses). Some nursery species were absent on reef sites furthest from nursery habitats (80km) and at 8km from seagrass habitats the proportion of nursery/non-nursery species as well as abundance and biomass of seagrass nursery species drastically changed, indicating a threshold distance at which migrations may cease. A similar pattern was found between 3 and 6 km from channels. Threshold distances were found where ontogenetic movement from nurseries to reefs appeared to cease and these distances differed between fish families. Isolation and arrangement of nursery habitats were also found to structure adult fish communities on reefs, highlighting the importance of considering the matrix (sand and deep water) as barriers for fish migration.
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| 6. |
- Berkström, Charlotte, et al.
(författare)
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Thresholds in seascape connectivity : the spatial arrangement of nursery habitats structure fish communities on nearby reefs
- 2020
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 43:6, s. 882-896
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Tidskriftsartikel (refereegranskat)abstract
- Ecosystems are linked by the movement of organisms across habitat boundaries and the arrangement of habitat patches can affect species abundance and composition. In tropical seascapes many coral reef fishes settle in adjacent habitats and undergo ontogenetic habitat shifts to coral reefs as they grow. Few studies have attempted to measure at what distances from nursery habitats these fish migrations (connectivity) cease to exist and how the abundance, biomass and proportion of nursery species change on coral reefs along distance gradients away from nursery areas. The present study examines seascape spatial arrangement, including distances between habitats, and its consequences on connectivity within a tropical seascape in Mozambique using a seascape ecology approach. Fish and habitat surveys were undertaken in 2016/2017 and a thematic habitat map was created in ArcGIS, where cover and distances between habitat patches were calculated. Distance to mangroves and seagrasses were significant predictors for abundance and biomass of most nursery species. The proportions of nursery species were highest in the south of the archipelago, where mangroves were present and decreased with distance to nurseries (mangroves and seagrasses). Some nursery species were absent on reef sites farthest from nursery habitats, at 80 km from mangroves and at 12 km from seagrass habitats. The proportion of nursery/non-nursery snapper and parrotfish species, as well as abundance and biomass of seagrass nursery species abruptly declined at 8 km from seagrass habitats, indicating a threshold distance at which migrations may cease. Additionally, reefs isolated by large stretches of sand and deep water had very low abundances of several nursery species despite being within moderate distances from nursery habitats. This highlights the importance of considering the matrix (sand and deep water) as barriers for fish migration.
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| 7. |
- Eggertsen, Linda, et al.
(författare)
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Effects of tidal current-induced flow on reef fish behaviour and function on a subtropical rocky reef
- 2016
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 559, s. 175-192
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Tidskriftsartikel (refereegranskat)abstract
- Tidal currents are important features in reef environments with high tidal range. Such current-influenced areas can be attractive for fish due to transport of nutrients and food items. Biological sampling, however, is difficult in these environments and it remains poorly understood to what degree strong currents actually shape tropical and subtropical reef fish communities. We used remote underwater video to investigate effects of flow velocity on fish across the tidal cycle at a rocky reef in southern Mozambique. Fish were recorded during flow velocities ranging from 0 to 1.44 m s(-1). Current flow velocity had no significant effect on the benthic fish assemblage, while increasing flow velocity had a negative effect on pelagic fish abundance and influenced trophic group composition. Limits for tolerated flow velocity on the pelagic assemblage were species-specific, with the highest resistance for larger predatory fish using subcarangiform swimming. Flow velocity had significant positive effects on size of Caranx spp., showing that smaller individuals had lower tolerance to flow than larger conspecifics. Planktivorous pomacentrids and monodactylids were very abundant in flows up to 0.5 m s(-1), suggesting that the area functions as an important foraging ground for planktivorous fish up to this flow velocity, while abundance of barracudas Sphyraena spp. was higher in moderate currents compared to slack water. For the benthic assemblage, benthic structures seemed to provide sufficient flow refuge for fish throughout the tidal cycle, highlighting the importance of structural complexity for benthic fish in this environment. Fish assemblages on reefs subjected to strong tidal currents might therefore be sensitive to habitat modifications. The ecological importance of tidal currents should be considered in marine management.
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| 8. |
- Eggertsen, Linda, 1981-
(författare)
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Identification and implications of fish nurseries in tropical and subtropical seascapes
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many species of reef fish reside in specific nursery habitats as juveniles. Seagrass meadows, and mangroves are examples of well-recognized nursery habitats, but only recently canopy-forming seaweeds have been found to provide important habitats for some fish species in the tropics. Availability of nurseries can have effects on the abundance and spatial distribution of adult fish, which is why it is important to recognize key nursery habitats for proper management. Information on reef fish nurseries is largely lacking in the South Western Atlantic (SWA), while information in the Western Indian Ocean (WIO) and elsewhere is more extensive. However, more information on the consequences of nursery availability on adult fish populations is needed. This thesis studies nursery habitat use of reef fish on tropical and subtropical reefs in the SWA and in seagrass and reef systems in the WIO. The hypothesis that seagrass and canopy-forming macroalgae meadows function as a nursery habitat for reef fish is tested in the SWA. The aim of this thesis is also to understand distribution patterns of fish arising from the arrangement of the seascape, using a seascape ecology approach, linking patterns to non-reef nursery habitat use (mangroves and seagrass systems). Results showed that spatial and temporal patterns of juvenile reef fish abundance were weak on rocky, subtropical reefs in the SWA (Paper I), while there was a stronger preference for certain habitats on SWA tropical biogenic reefs, especially seaweed beds dominated by Sargassum (Paper II). The widely accepted paradigm that seagrass meadows function as nursery habitats for reef fish was not supported by the results from the study site in the tropical SWA (Paper II). This may be related to habitat availability in the seascape. In the SWA, seagrass meadows are spatially small, fragmented and less complex, compared to in the WIO, where they display high structural complexity and cover large areas. At the WIO study site (Bazaruto Archipelago), the juvenile fish assemblage in the seagrass meadows encompassed a number of reef fish species from a range of trophic groups and families, as well as resident seagrass species (Paper III). Key variables and extent of spatial scales that structure ontogenetic migrations were identified in both seagrass and reef habitats. Fish distribution patterns in the seagrass seascape was strongly influenced by seascape configuration and distance to adjacent habitats, highlighting that not all seagrass meadows are equally productive as nursery habitats. Variables important for distribution patterns of fish were identified, which in most cases were species-specific, and related to life history and functional traits of species. Effects of two small protected areas on the fish assemblage was also linked to geographical placement of reserves in the seascape. Likewise, the adult fish community composition on the reefs was found to be structured by the spatial arrangement of nursery habitats in the seascape, and presence of stretches of sand acting as isolating barriers (Paper IV). Nursery fish species were less abundant on reefs far from nurseries, resulting in differences in community and functional group composition along distance gradients in the seascape. Depending on functional traits of the nursery fish assemblage, seagrass and mangroves can enhance certain ecological functions on reefs. Both community structure and ecosystem functioning may therefore change depending on nursery habitat availability, highlighting the need to adopt a holistic seascape approach in management.
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| 9. |
- Eggertsen, Linda, 1981-, et al.
(författare)
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Identifying reef fish nursery habitats on subtropical rocky reefs in the Southwestern Atlantic
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Availability of nursery habitats can potentially limit adult populations of reef fish. Suitable nursery habitats are often shallow and located close to shore, and in many cases overlap with anthropogenic stressors and human activities. For proper management of reef fish communities it is therefore important to identify these habitats and minimize conflicts of habitat use in time and space. To identify potential spatial and temporal patterns of nursery habitat use, the reef fish communities on subtropical rocky reefs in the South western Atlantic were surveyed with under water visual census. Surveys were performed in summer and winter months during two years, along a depth gradient on marginal reefs and in seasonal Sargassum macroalgal beds. No clear patterns in total juvenile abundance and distribution were distinguished between seasons, although some families occurred in significantly higher abundances in summer months (Haemulidae and Sparidae). There were large variances in juvenile abundance between the two surveyed summers, with low total abundance in the summer of 2017, which could be linked to weak upwelling in the area and hampered growth of Sargassum. Similar to in other locations globally, climatic events that affect biomass of Sargassum may hence have large effects on fish recruitment also in the South western Atlantic. In general, shallow areas in sheltered bays had higher abundances of juvenile fish, especially when Sargassum was present in these locations. Spatial patterns of acanthurids and labrid scarinae, were more homogenous compared to those of tropical reefs in the South western Atlantic, where Sargassum beds harbor significantly more juveniles than other habitats. We suggest that fish in sub-tropical rocky reef environments in the South western Atlantic have access to less habitat diversity and complex substrate to use as nursery areas, and thus shallow, sheltered and vegetated habitats are critical for many species. Additionally, those habitats are also the most threatened by human uses demanding proper management.
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| 10. |
- Eggertsen, Linda, et al.
(författare)
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Seascape Configuration Leads to Spatially Uneven Delivery of Parrotfish Herbivory across a Western Indian Ocean Seascape
- 2020
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Ingår i: Diversity. - : MDPI AG. - 1424-2818. ; 12:11
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Tidskriftsartikel (refereegranskat)abstract
- Spatial configuration of habitat types in multihabitat seascapes influence ecological function through links of biotic and abiotic processes. These connections, for example export of organic matter or fishes as mobile links, define ecosystem functionality across broader spatial scales. Herbivory is an important ecological process linked to ecosystem resilience, but it is not clear how herbivory relates to seascape configuration. We studied how herbivory and bioerosion by 3 species of parrotfish were distributed in a multi-habitat tropical seascape in the Western Indian Ocean (WIO). We surveyed the abundance of three species with different life histories-Leptoscarus vaigiensis (seagrass species), Scarus ghobban (juvenile-seagrass/adults-reefs) and Scarus rubroviolaceus (reef species) -in seagrass meadows and on reefs and recorded their selectivity of feeding substrate in the two habitats. Herbivory rates for L. vaigiensis and S. ghobban and bioerosion for S. rubroviolaceus were then modelled using bite rates for different size classes and abundance and biomass data along seascape gradients (distance to alternative habitat types such as land, mangrove and seagrass). Bioerosion by S. rubroviolaceus was greatest on reefs far from seagrass meadows, while herbivory rates by S. ghobban on reefs displayed the opposite pattern. Herbivory in seagrass meadows was greatest in meadows close to shore, where L. vaigiensis targeted seagrass leaves and S. ghobban the epiphytes growing on them. Our study shows that ecological functions performed by fish are not equally distributed in the seascape and are influenced by fish life history and the spatial configuration of habitats in the seascape. This has implications for the resilience of the system, in terms of spatial heterogeneity of herbivory and bioerosion and should be considered in marine spatial planning and fisheries management.
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| 11. |
- Eggertsen, Linda, et al.
(författare)
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Seaweed beds support more juvenile reef fish than seagrass beds in a south-western Atlantic tropical seascape
- 2017
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 196:5, s. 97-108
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Tidskriftsartikel (refereegranskat)abstract
- Seascape connectivity is regarded essential for healthy reef fish communities in tropical shallow systems. A number of reef fish species use separate adult and nursery habitats, and hence contribute to nutrient and energy transfer between habitats. Seagrass beds and mangroves often constitute important nursery habitats, with high structural complexity and protection from predation. Here, we investigated if reef fish assemblages in the tropical south-western Atlantic demonstrate ontogenetic habitat connectivity and identify possible nurseries on three reef systems along the eastern Brazilian coast. Fish were surveyed in fore reef, back reef, Halodule wrightii seagrass beds and seaweed beds. Seagrass beds contained lower abundances and species richness of fish than expected, while Sargassum-dominated seaweed beds contained significantly more juveniles than all other habitats (average juvenile fish densities: 32.6 per 40 m2 in Sargassum beds, 11.2 per 40 m2 in back reef, 10.1 per 40 m2 in fore reef, and 5.04 per 40 m2 in seagrass beds), including several species that are found in the reef habitats as adults. Species that in other regions worldwide (e.g. the Caribbean) utilise seagrass beds as nursery habitats were here instead observed in Sargassum beds or back reef habitats. Coral cover was not correlated to adult fish distribution patterns; instead, type of turf was an important variable. Connectivity, and thus pathways of nutrient transfer, seems to function differently in east Brazil compared to many tropical regions. Sargassum-dominated beds might be more important as nurseries for a larger number of fish species than seagrass beds. Due to the low abundance of structurally complex seagrass beds we suggest that seaweed beds might influence adult reef fish abundances, being essential for several keystone species of reef fish in the tropical south-western Atlantic.
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| 12. |
- Eggertsen, Linda, 1981-, et al.
(författare)
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Where is the grass greenest? Influence of seascape structure and marine protected areas on fish distribution patterns in a seagrass-dominated landscape
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Ingår i: Ecography. - 0906-7590 .- 1600-0587.
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Tidskriftsartikel (refereegranskat)abstract
- Tropical seagrass beds are critical habitats for many resident- and nursery fish species. While numerous studies have explored factors that structure reef fish assemblages, few have investigated the relative influence of multiple factors at fine- and large spatial scales as well as MPAs on seagrass fish. To understand which are the most important factors structuring fish assemblages in tropical seagrass beds, and how this is related to life history of species, we investigated fish distribution patterns at 20 sites in 13 different seagrass beds across the Bazaruto Archipelago, Mozambique. Using boosted regression tree modelling, we assessed the influence of fine-scale variables (seagrass meadow characteristics) and seascape variables (distance to adjacent habitats) on abundance of four nursery taxa (Lutjanus fulviflamma, Lethrinus spp., Scarus ghobban and Gerres spp.) and two resident species (Pelates quadrilineatus and Leptoscarus vaigiensis). We found that seascape variables were generally more important than seagrass characteristics, and that the influence of different variables was highly taxon-specific. Fish distribution patterns in seagrass-dominated seascapes were related to life history traits of the species; nursery fish taxa were negatively correlated with distance to adult habitats, while resident species occurred in higher abundances far from reefs. Proximity to mangroves was important for taxa that utilised mangroves in addition to seagrass as nurseries. Most seascape variables influenced fish abundances on a large spatial scale (km). The influence of protected areas was taxon-specific, with stronger effects on resident species than on nursery species, with geographical placement shadowing potential effects of protection on fish abundance. Our results indicate that protection efforts in seagrass-dominated seascapes can have varying impacts on fish distribution, depending on the geographical location of the reserve. This highlights the importance of considering seascape arrangement and the ecology of targeted species for conservation and marine spatial planning in seagrass-dominated systems.
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| 13. |
- Eggertsen, Linda, 1981-, et al.
(författare)
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Where the grass is greenest in seagrass seascapes depends on life history and simple species traits of fish
- 2022
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Ingår i: Estuarine, Coastal and Shelf Science. - : Academic Press. - 0272-7714 .- 1096-0015. ; 266
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Tidskriftsartikel (refereegranskat)abstract
- Tropical seagrass meadows are critical habitats for many fish species, yet few studies have investigated the influence of multiple scale-dependent factors and marine protected areas on seagrass fish species of differing life histories. We assessed the influence of fine-scale seagrass meadow characteristics and seascape-scale variables on the abundance of fish in a seagrass-dominated seascape in the Bazaruto Archipelago, Mozambique, particularly examining patterns of nursery- vs. resident species as well as mobile- vs. sedentary species. We found that fish distribution patterns in this seagrass-dominated seascape were dependent on species’ life history characteristics; nursery taxa showed lower abundance in seagrass meadows further from adult reef habitats, while resident species within seagrass meadows occurred in higher abundances far from reefs. For taxa utilizing both mangroves and seagrass meadows as nursery habitat, proximity to mangroves was an important factor. Fish abundances were generally influenced by variables at the seascape scale (km), while sedentary species were predominantly influenced by area variables, and smaller seascapes (<500 m in radius) better explained distribution patterns. The influence of marine protected areas was taxon-specific, with the strongest effects of protection on resident species. Our results indicate that protection efforts in seagrass-dominated seascapes can have varying impacts on fish distribution, depending on the life history of the species present, and the geographical placement of the reserve within the seascape. Further, we suggest that simple species attributes can be utilised to describe generalized abundance patterns of fish in seagrass seascapes.
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| 14. |
- Fontoura, Luisa, et al.
(författare)
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Protecting connectivity promotes successful biodiversity and fisheries conservation
- 2022
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375:6578, s. 336-
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Tidskriftsartikel (refereegranskat)abstract
- The global decline of coral reefs has led to calls for strategies that reconcile biodiversity conservation and fisheries benefits. Still, considerable gaps in our understanding of the spatial ecology of ecosystem services remain. We combined spatial information on larval dispersal networks and estimates of human pressure to test the importance of connectivity for ecosystem service provision. We found that reefs receiving larvae from highly connected dispersal corridors were associated with high fish species richness. Generally, larval "sinks" contained twice as much fish biomass as "sources" and exhibited greater resilience to human pressure when protected. Despite their potential to support biodiversity persistence and sustainable fisheries, up to 70% of important dispersal corridors, sinks, and source reefs remain unprotected, emphasizing the need for increased protection of networks of well-connected reefs.
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| 15. |
- Hammar, Linus, 1979, et al.
(författare)
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A Probabilistic Model for Hydrokinetic Turbine Collision Risks: Exploring Impacts on Fish
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 10:3, s. e0117756-
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Tidskriftsartikel (refereegranskat)abstract
- A variety of hydrokinetic turbines are currently under development for power generation in rivers, tidal straits and ocean currents. Because some of these turbines are large, with rapidly moving rotor blades, the risk of collision with aquatic animals has been brought to attention. The behavior and fate of animals that approach such large hydrokinetic turbines have not yet been monitored at any detail. In this paper, we conduct a synthesis of the current knowledge and understanding of hydrokinetic turbine collision risks. The outcome is a generic fault tree based probabilistic model suitable for estimating population-level ecological risks. New video-based data on fish behavior in strong currents are provided and models describing fish avoidance behaviors are presented. The findings indicate low risk for small sized fish. However, at large turbines (≥5 m), bigger fish seem to have high probability of collision, mostly because rotor detection and avoidance is difficult in low visibility. Risks can therefore be substantial for vulnerable populations of large-sized fish, which thrive in strong currents. The suggested collision risk model can be applied to different turbine designs and at a variety of locations as basis for case-specific risk assessments. The structure of the model facilitates successive model validation, refinement and application to other organism groups such as marine mammals.
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| 16. |
- Hammar, Linus, 1979, et al.
(författare)
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Hydrokinetic Turbine Effects on Fish Swimming Behaviour
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 8:12, s. artikel nr e84141-
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Tidskriftsartikel (refereegranskat)abstract
- Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbinesalready deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affectfish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axishydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurringfish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showedthat no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced theirmovements through the area when the rotor was present. This deterrent effect on fish increased with current speed.Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fishwere particularly cautious of the rotor and never moved closer than 1.7 m in current speeds above 0.6 ms-1. Theeffects of the rotor differed among taxa and feeding guilds and it is suggested that fish boldness and body shapeinfluenced responses. In conclusion, the tested hydrokinetic turbine rotor proved non-hazardous to fish during theinvestigated conditions. However, the results indicate that arrays comprising multiple turbines may restrict fishmovements, particularly for large species, with possible effects on habitat connectivity if migration routes areexploited. Arrays of the investigated turbine type and comparable systems should therefore be designed with gaps ofseveral metres width to allow large fish to pass through. In combination with further research the insights from thisstudy can be used for guiding the design of hydrokinetic turbine arrays where needed, so preventing ecologicalimpacts.
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| 17. |
- Hammar, Linus, 1979, et al.
(författare)
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Stereo-Video Methodology for Quantitative Analysis of Fish-Turbine Interactions
- 2012
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Ingår i: 1st Asian Wave and Tidal Conference Series. ; , s. 8-
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Konferensbidrag (refereegranskat)abstract
- Tidal power turbines are developed to reach the ambition of supplying coastal communities with renewable energy. However, little is still known about the potential environmental effects on the local ecosystems and what rotor design can do to minimize such effects. The knowledge gap includes fish behavior around tidal power rotors and adequate sampling techniques for such studies. In this contribution stereo-video methodology has been used for monitoring fish movements at an operating model of a vertical-axis tidal turbine rotor. The results show that stereo-video methodology offers excellent opportunities for detailed analysis of fish behavior and several recommendations of how to optimize such sampling are provided. Preliminary results of fish-turbine interactions are presented.
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| 18. |
- Massei, Karina, et al.
(författare)
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Analysis of marine diversity and anthropogenic pressures on Seixas coral reef ecosystem (northeastern Brazil)
- 2023
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 905
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Tidskriftsartikel (refereegranskat)abstract
- Coral reefs, vital and ecologically significant ecosystems, are among the most jeopardized marine environments in the Atlantic Ocean, particularly along the northeastern coast of Brazil. The persistent lack of effective management and conservation has led to fragmented information on reef use and pressures, hindering the under-standing of these ecosystems' health. Major difficulties and challenges include inadequate data, diverse anthropogenic pressures, and the complex interaction between marine species. This study sought to bridge this knowledge gap by conducting a comprehensive analysis of marine diversity and anthropogenic pressures, specifically focusing on Seixas coral reef near Joa similar to o Pessoa city, an area notably impacted by tourism. Utilizing 25 monitoring transects, subdivided into 1 m2 quadrants, the marine diversity was meticulously evaluated through innovative procedures including (a) sedimentological and geochemical field surveys, (b) application of Shannon -Weaver diversity and Simpson dominance indices, (c) cluster analysis, (d) species identification of macroalgae, coral, and fish, and (e) an examination of anthropogenic interactions and pressures on the coral reef. The assessment encompassed three distinct zones: Back Reef, Reef Top, and Fore Reef, and identified a total of 25 species across 15 genera and 10 fish families. The findings revealed the prevalence of brown macroalgae, fish, and coral, with heightened abundance of red macroalgae in the Fore Reef, which also exhibited the greatest diversity (2.816) and dominance (0.894). Original achievements include the identification of specific spatial variations, recognition of the anthropogenic factors leading to ecological changes, and the formulation of evidence-based recommendations. The study concludes that escalating urbanization and burgeoning daily tourist visits to the reef have exacerbated negative impacts on Seixas coral reef's marine ecosystem. These insights underscore the urgent need for strategic planning and resource management to safeguard the reef's biodiversity and ecological integrity.
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