| 1. |
- Graham, Nicholas A. J., et al.
(författare)
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Climate Warming, Marine Protected Areas and the Ocean-Scale Integrity of Coral Reef Ecosystems
- 2008
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 3:8, s. e3039-
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Tidskriftsartikel (refereegranskat)abstract
- Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change.
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| 2. |
- Garpe, Kajsa C., et al.
(författare)
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Long-term effects of the 1998 coral bleaching event on reef fish assemblages
- 2006
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 315, s. 237-247
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Tidskriftsartikel (refereegranskat)abstract
- Coral bleaching events constitute compound disturbances often resulting in coral death as well as successive degradation of the reef framework. The 1997/1998 El Niño Southern Oscillation (ENSO) was the most severe on record and affected coral reefs worldwide. The present study examined the response of fish assemblages in plots of transplanted coral before and after the 1998 bleaching. Multidimensional scaling ordinations (MDS) demonstrate significant changes in assemblage composition related to habitat alteration. Within-site variability increased with disturbance, the increase being most apparent following substrate erosion. The differences in long-term responses as opposed to short-term responses were striking. Six mo after coral death, total abundance as well as taxonomic richness had increased at one of the sites, but not the other, whereas 6 yr later, both measures had decreased significantly at both sites. Functional groups, with documented affiliations with coral, were significantly influenced by the habitat alteration. Herbivore abundance increased as an immediate response to bleaching, but was subsequently decimated in eroded habitat. The loss of structural complexity had major detrimental effects on the entire fish community. In conclusion, we present evidence of severe and long-lasting secondary impacts of a catastrophic bleaching event, with no apparent recovery. The discrepancies between short-term and long-term responses underline the importance of long-term monitoring of fish assemblages following habitat alteration.
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| 3. |
- Garpe, Kajsa C, et al.
(författare)
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Non-random habitat use by coral reef fish recruits in Mafia Island Marine Park, Tanzania
- 2007
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Ingår i: African Journal of Marine Science. - : Informa plc. - 1814-232X. ; 29:2, s. 187-199
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Tidskriftsartikel (refereegranskat)abstract
- The habitat use by nearly 3 000 reef fish recruits, comprising 56 taxa, at seven sites in Mafia Island Marine Park, Tanzania, were examined. The study was carried out following the 1998 global coral bleaching event and all sites but one were dominated by dead coral and rubble. Mean recruit densities ranged between 0.1 m-2 and 0.7 m-2 among sites. Although live coral represented only 15% of the overall substrate composition, almost half of all observed recruits were found associated with this substrate. Pooled across all sites, 46% of the recruits used live coral cover in disproportion to availability. Principal component analyses were applied to explore microhabitat use by the 11 most common recruit taxa in comparison to availability. Among these taxa, 10 exhibited nonrandom microhabitat use and six associated with live coral in disproportion to availability. A comparison with the adult fish community revealed that adult abundances of four of the six coral selective recruit taxa were significantly correlated with live coral. The study demonstrated that reef fish recruits use microhabitats non-randomly and that a substantial proportion is selective towards live coral.
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| 4. |
- Andersson, Mathias H., et al.
(författare)
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Epibenthic colonization of concrete and steel pilingsin a cold-temperate embayment : a feld experiment
- 2009
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Ingår i: Helgoland Marine Research. - : Springer Science and Business Media LLC. - 1438-387X .- 1438-3888. ; 63:3, s. 249-260
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Tidskriftsartikel (refereegranskat)abstract
- With large-scale development of offshore wind farms, vertical structures are becoming more common in open water areas. To examine how vertical structures of different materials may be colonized by epibenthic organisms, an experiment was carried out using steel and concrete pilings constructed to resemble those commonly used in wind farm constructions as well as in bridges, jetties and oil platforms. The early recruitment and succession of the epibenthic communities were sampled once a month for the first 5 months and then again after 1 year. Further, the fish assemblages associated with the pillars were sampled and compared to natural areas. The main epibenthic species groups, in terms of coverage, diVered between the two materials at five out of six sampling occasions. Dominant organisms on steel pillars were the barnacle Balanus improvisus,the calcareous tubeworm Pomatoceros triqueter and the tunicate Ciona intestinalis. On the concrete pillars, the hydroid Laomedea sp. and the tunicates Corella parallelogramma and Ascidiella spp. dominated. However, there was no different in coverage at different heights on the pillars or in biomass and species abundance at different directions (north-east or south-west) 5 months after submergence. Fish showed overall higher abundances and species numbers on the pillars (but no difference between steel and concrete)compared to the surrounding soft bottom habitats but not compared to natural vertical rock walls. Two species were attracted to the pillars, indicating a reef effect; Gobiusculus flavescens and Ctenolabrus rupestris. The bottom-dwelling gobies, Pomatoschistus spp., did not show such preferences.
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| 5. |
- Andersson, Mathias H, 1976-, et al.
(författare)
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Importance of Using Multiple Sampling Methodologies for Estimating of Fish Community Composition in Offshore Wind Power Construction Areas of the Baltic Sea
- 2007
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 36:8, s. 634-636
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Tidskriftsartikel (refereegranskat)abstract
- It is standard procedure that an Environmental Impact Assessment (EIA) is conducted before larger constructions are built. To adequately describe the impact, methods used in an EIA should be carefully adapted considering both the character of the constructions under development and the environment that will be affected. Various sampling techniques are applied to estimate fish abundances and species composition. Methods used, including trawling, seine and gill netting, angling, echo-sound sampling, fishery data, video recordings, dredging, and visual counts using SCUBA, will all give different estimates of fish community composition.
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| 6. |
- Andersson, Mathias H, 1976-, et al.
(författare)
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Swimming Behavior of Roach (Rutilus rutilus) and Three-spined Stickleback (Gasterosteus aculeatus) in Response to Wind Power Noise and Single-tone Frequencies
- 2007
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 36:8, s. 636-638
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Tidskriftsartikel (refereegranskat)abstract
- Human-induced underwater noise is drastically increasing as the result of offshore installations and human activities in the marine environment. Many of these structures and activities produce low-frequency noise that could potentially disturb or have harmful effects on several species of teleost fishes. Within the next decade, thousands of wind turbines will be in use in coastal and offshore waters and there is increasing concern on how they may influence marine life. The aims of this study were to examine how swimming behavior of roach (Rutilus rutilus) and three-spined stickleback (Gasterosteus aculeatus) were influenced by single-frequency sounds and noise generated by an offshore wind turbine, and the function of sound pressure level.
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| 7. |
- Gullström, Martin, et al.
(författare)
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Assessment of vegetation changes in seagrass communities of tropical Chwaka Bay (Zanzibar) using satellite remote sensing
- 2006
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 67:3, s. 399-408
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Tidskriftsartikel (refereegranskat)abstract
- Spatial and temporal dynamics of submerged aquatic vegetation (SAV) cover were studied in the relatively pristine and seagrass-dominated area of Chwaka Bay, Zanzibar (Tanzania) by using satellite remote sensing. Through complementary field work the potential of the technique for change detection was verified. The general changes in SAV cover were examined using Landsat images from 1986, 1987, 1998, 2001 and 2003. Two of these images, from 1987 (Landsat TM) and 2003 (Landsat ETM+), were specifically analysed to create a map of the change in SAV cover. Overall, the general distribution of SAV stayed fairly stable over the period investigated, but the result also showed regions where significant alterations, both losses and gains, had occurred between the two years. Based on our findings and anecdotal information from local fishermen and seaweed farmers potential causative factors are discussed. It was concluded that a repeated mapping with satellite remote sensing is a suitable tool to monitor changes of seagrass and seaweed distribution in shallow tropical environments.
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