| 1. |
- Ahrné, Karin, et al.
(författare)
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Tillstånd och trender för arter och deras livsmiljöer – rödlistade arter i Sverige 2015
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 2015 års upplaga av den svenska rödlistan är den fjärde i ordningen. Den är baserad på IUCN:s rödlistningskriterier och revideras vart femte år. I rödlistan bedöms risken som enskilda arter av djur, växter och svampar löper att försvinna från Sverige. Bedömningen utförs av ArtDatabankens medarbetare i samverkan med över 100 externa experter, indelade i 14 expertkommittéer för olika organismgrupper. Under arbetet med 2015 års rödlista har tillstånd och trender bedömts för 21 600 arter och 1 318 lägre taxa (apomiktiska arter, underarter och varieteter), sammanlagt ca 22 900 taxa. Av de bedömda arterna klassificerades 2 029 som hotade (kategorierna CR, EN och VU) och 4 273 som rödlistade (inkluderar även kategorierna NT, RE och DD). Förhållandet mellan antalet rödlistade och antalet bedömda arter ar 19,8 %, vilket är ungefär samma värde som 2010 och 2005. I denna rapport jämförs antalet och andelen rödlistade arter mellan olika organismgrupper, biotoper, substrat och påverkansfaktorer. Texten ar indelad i en allmän del och åtta kapitel inriktade på olika landskapstyper. Landskapstyperna utgör en grov indelning av landets miljöer enligt följande kategorier: Skog, Jordbrukslandskap, Urbana miljöer, Fjäll, Våtmarker, Sötvatten, Havsstränder och Havsmiljöer. Skogen och jordbrukslandskapet är de artrikaste landskapstyperna med 1 800 respektive 1 400 arter som har en stark anknytning dit, och ytterligare flera hundra arter som förekommer där mer sporadiskt. De faktorer som påverkar flest rödlistade arter i Sverige är skogsavverkning och igenväxning, som båda utgör ett hot mot vardera ca 30 % av de rödlistade arterna. Avverkning minskar arealen av skog där naturliga strukturer och naturlig dynamik upprätthålls, och den orsakar därmed förlust av livsmiljöer. Igenväxning orsakas av ett antal faktorer, bland annat upphörande hävd (bete och slåtter), gödsling, trädplantering och brist på naturliga störningsregimer som t.ex. regelbundna översvämningar kring vattendrag och sjöar. Andra viktiga påverkansfaktorer är fiske, torrläggning av våtmarker, tillbakagång hos värdarter (främst alm och ask som drabbats av invasiva svampsjukdomar), klimatförändringar och konkurrens från invasiva arter. IUCN:s rödlisteindex beräknas för ett urval av de bedömda organismgrupperna. Rödlisteindex visar att skillnaderna mellan rödlistorna från 2000, 2005, 2010 och 2015 är små. Ett par undantag finns dock. Groddjur och stora däggdjur har fått en något förbättrad situation sedan 2000. Totalt förefaller det ändå som att trycket mot Sveriges artstock har förblivit relativt konstant under de senaste 15 åren.
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| 2. |
- Aronsson, Mora, et al.
(författare)
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Sveriges arter och naturtyper i EU:s art- och habitatdirektiv : Resultat från rapportering 2019 till EU av bevarandestatus 2013-2018
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sverige har en variationsrik natur med storslagen fjällmiljö, myllrande våtmarker, vattendrag och sjöar, kust och hav, skogar och odlingslandskap, alla med ett rikt växt och djurliv. Den här fantastiska biologiska mångfalden tas ofta för given och ibland som en lyx, men oavsett vilket är det en förutsättning för vår överlevnad.2019 rapporterade Sverige statusen till EU för perioden 2013–2018 för de naturtyper och arter i Sverige som är listade i art- och habitatdirektivet. Den berättar att 20 procent av naturtyperna och 40 procent av arterna mår bra. Den biologiska mångfalden är hårt trängd i såväl Sverige som i andra EU-länder.Den här rapporten sammanfattar Sveriges rapportering och innehåller beskrivningar av status för naturtyper och arter, påverkan, hot och trender. Rapporten ger kunskap om tillståndet för den biologiska mångfalden i Sverige med hjälp av de arter och naturtyper som är listade i EU:s art- och habitatdirektiv.Rapporten visar hur naturmiljöerna i Sverige förändas, och sammanfattar den senaste kunskapen om vilka faktorer som driver dessa förändringar. Även exempel på hur vi genom restaurerings- och skötselåtgärder kan hejda förlusten av biologisk mångfald tas upp.
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| 3. |
- Bergström, Lena, et al.
(författare)
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Biodiversitet och ekosystemtjänster i kustområden
- 2021
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Ingår i: Biologisk mångfald, naturnyttor och ekosystemtjänster. - : Sveriges Lantbruksuniversitet. - 9789188083357 - 9789188083364 - 9789162013073 ; , s. 209-219
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Bokkapitel (refereegranskat)
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| 4. |
- Bergström, Lena, et al.
(författare)
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Klimatförändringar och biologisk mångfald : Slutsatser från IPCC och IPBES i ett svenskt perspektiv.
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- De stora miljö- och samhällsproblemen kommer inte ensamma. De är sammankopplade på olika sätt. Detta innebär utmaningar men ger också möjligheter att utveckla åtgärder och lösningar. Det gäller både för klimatfrågan och frågan om att motverka förlusten av biologisk mångfald och ekosystem. Kunskapens betydelse för att hantera dessa och andra aspekter är ovärderlig, såväl kring specifika frågeställningar som kring omständigheter och förutsättningar för åtgärdsarbetet.Den här kunskapssammanställningen har gjorts av forskare från Lunds universitet och Sveriges lantbruksuniversitet på uppdrag av Naturvårdsverket och SMHI. Forskarna har tagit avstamp i de omfattande kunskapsutvärderingar som gjorts av den mellanstatliga klimatpanelen (IPCC) och den mellanstatliga plattformen för biologisk mångfald (IPBES). Slutsatserna från IPCC och IPBES sätts i ett svenskt perspektiv, bland annat genom utvalda exempel vilka fungerar som aktuella illustrationer av hur klimatförändringar påverkar biologisk mångfald och ekosystem i Sverige.
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| 5. |
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| 6. |
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| 7. |
- Calvo-Ugarteburu, Gurutze, et al.
(författare)
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Rehabilitating mussel beds in Coffee Bay, South Africa : Towards fostering cooperative small-scale fisheries governance and enabling community upliftment
- 2017
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 46:2, s. 214-226
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Tidskriftsartikel (refereegranskat)abstract
- Along the coast of South Africa, marine resources play a significant role in supporting livelihoods and contributing to food security in impoverished rural communities. Post-apartheid fisheries laws and policies have begun to address traditional fishing rights and development needs, and new management arrangements are being implemented. One such initiative has been the Mussel Rehabilitation Project in Coffee Bay, which piloted a resource rehabilitation technique at several overexploited fishing sites. Mussel stocks in these exploited areas had dropped to under 1 % mussel cover, and during the project period, stocks increased to[ 80 % cover, supporting a sustainable harvest well above national daily bag limits. This stock enhancement was achieved only after the project had started to address social challenges such as the lack of local management institutions and the need to enhance food security. The project embarked on training and institution-building; it formed a robust community mussel management committee; and developed a local resource management plan, facilitating increased community participation in the day-to-day management of the resource. The project also saw the initiation of various ancillary projects aimed at improving food security and stimulating the local economy and hence alleviating pressure on the marine resources. Here we review this 10-yearproject's outcomes, and present lessons for smallscale fisheries governance in South Africa and internationally. We show, through empirical experience, that balancing stock rebuilding needs in a context of widespread poverty and dependency on natural resources by a local fisher community can only be addressed through an integrated approach to development. Participation of resource users and a thorough understanding of the local context are imperative to negotiating appropriate smallscale fisheries governance approaches. We recommend that the implementation of South Africa's newly minted SmallScale Fisheries Policy should begin with bottom-up, demonstrative resource management measures such as mussel rehabilitation. This type of initiative can deliver short-term food security benefits and foster social learning towards sustainable and cooperative fisheries governance.
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| 8. |
- Chacin, D. H., et al.
(författare)
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Altered tropical seascapes influence patterns of fish assemblage and ecological functions in the Western Indian Ocean
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- The arrangement and composition of habitats within landscapes and fine-scale habitat characteristics influence community structure and ecological processes. These aspects can be altered by anthropogenic activities, thus influencing associated assemblages. Farming of macroalgae is a common practice in tropical settings and alters the natural composition of seascapes by introducing monoculture patches. The farmed macroalgae may also differ in palatability compared to naturally-occurring macroalgae, influencing herbivory. This study assessed how these farms may differ from natural macroalgal beds in terms of habitat heterogeneity, fish assemblages, and herbivory. We surveyed fish assemblages and deployed macroalgal assays within macroalgal beds, farms and at varying distances from these habitats near Mafia Island, Tanzania. Fish composition and herbivory differed between the habitats likely due to different macrophyte species richness, underlying hard substrate in natural macroalgal beds, and high abundance of browsers nearby the farms. Additionally, fish assemblage patterns and herbivory were not consistent across the seascapes and varied with distance from the focal habitats possibly due to the presence of other habitats. The results suggest alterations of seascapes by farming practices may have consequences on fish assemblages and the ecological functions performed, thus positioning of farms should be carefully considered in management and conservation plans.
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| 9. |
- Charisiadou, S., et al.
(författare)
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Coastal aquaculture in Zanzibar, Tanzania
- 2022
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Ingår i: Aquaculture. - : Elsevier. - 0044-8486 .- 1873-5622. ; 546
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Tidskriftsartikel (refereegranskat)abstract
- This study provides an overview of the multi-sectoral coastal aquaculture development in Zanzibar (Tanzania) over the last thirty years based on empirical evidence from interviews, field observations, policy reports and literature reviews. Despite the immense potential of aquaculture for food and livelihoods, only seaweed farming has so far established into commercial-scale production. This activity is dominated by women and became widespread in the early 1990s as a small but regular source of income. However, seaweed farming constraints such as frequent seaweed die-offs, as well as economic and institutional constraints inhibit its development. Other types of aquaculture activities such as fish farming, mud crab fattening, half-pearl farming, sea cucumber farming and sponge and coral cultures are under development with limited production or in experimental stages. Common constraints among these activities are economic limitations, lack of technical infrastructure and skills, small and irregular production, and limited trade and market availabilities. At the same time, there is a lack of sufficient management and monitoring systems, while there are no formal regulations or clear strategies to boost aquaculture at the national level. In addition, new aquaculture initiatives are often dominated by donor-driven projects instead of local entrepreneurships. This situation does not encourage engagement in aquaculture and thus such activities are outcompeted by other already established sectors (e.g. agriculture and fisheries). We conclude that aquaculture has great potential to evolve due to high environmental capacity. Nevertheless, achieving profitable production and a stronger commitment within local communities, as well as developing effective mariculture governance through support mechanisms and clear strategies to boost the sector at the national level, are essential for sustainable mariculture development in Zanzibar.
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| 10. |
- Dumilag, Richard V., et al.
(författare)
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Genotype introduction affects population composition of native Philippine Kappaphycus (Gigartinales, Rhodophyta)
- 2016
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Ingår i: Conservation Genetics Resources. - : Springer Science and Business Media LLC. - 1877-7252 .- 1877-7260. ; 8:4, s. 439-441
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Tidskriftsartikel (refereegranskat)abstract
- We present evidence on the presence of introduced red seaweed Kappaphycus cultivar in native Kappapphycus populations in Hoyanjog Island, Surigao del Norte, Philippines. This is the first actual report that native populations of Kappaphycus in the Philippines may possibly face genotype shifting from native to introduced. Our findings call for a challenge in conservation laws to design resource management strategies and to regulate Kappaphycus farming in sites where there are known native Kappaphycus genotypes.
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| 11. |
- Eggertsen, Maria, et al.
(författare)
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Contrasting distribution and foraging patterns of herbivorous and detritivorous fishes across multiple habitats in a tropical seascape
- 2019
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 166:4
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Tidskriftsartikel (refereegranskat)abstract
- Understanding drivers behind patterns of functionally important groups of fishes is crucial for successful management and conservation of tropical seascapes. Herbivorous fishes are the most prominent consumers of marine primary production which can have profound effects on reef resilience. We explored environmental variables affecting distribution and foraging patterns of herbivorous and detritivorous fish assemblages (siganids, acanthurids and parrotfish) across distinct shallow-water habitats (coral reefs, macroalgae beds and seagrass meadows) during September-November 2016 at Mafia Island, Tanzania (8 degrees 00S, 39 degrees 41E). We performed underwater visual census to quantify fish assemblages, measured habitat features, deployed macroalgal assays and conducted inventories of grazing scars. Multi-dimensional scaling and mixed-effects linear models were used to evaluate differences in fish assemblages and environmental variables influencing abundance and foraging patterns of fishes. Fish communities of focal functional groups differed among habitats. Abundance of herbivores and detritivores as well as relative browsing and scraping was highest on coral reefs compared to macroalgae and seagrass meadows.Adult fish were more abundant on coral reefs while juveniles were abundant in macroalgal beds. Coral cover and crustose coralline algal cover had a positive effect on the abundance of fish in coral reef areas, while macroalgal cover had a negative effect. Contrastingly, in macroalgae habitats, macroalgal cover had a positive effect on the abundance of parrotfish. These results highlight the importance of considering connectivity between macroalgal beds and coral reefs through ontogenetic shifts in habitat use by primarily microphagous parrotfish and of incorporating a range of habitats within coastal management plans.
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| 12. |
- Eggertsen, Maria, 1981-, et al.
(författare)
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Coral-macroalgae interactions : herbivory and substrate type influence growth of the macroalgae Eucheuma denticulatum on a tropical reef
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Invasive macroalgae can alter coral reef habitats by causing phase shifts from coral to macroalgal domination with negative ecological effects and dramatic reductions in coral cover. In Tanzania, South East Asian haplotypes of the macroalgae Eucheuma denticulatum, documented to overgrow reef corals in other locations, have been introduced through seaweed farming practices. In this study we examine growth and holdfast development of introduced and native E. denticulatum on live and dead branches of Acropora sp. in the presence and absence of herbivores in Unguja Island, Zanzibar. Coral and macroalgae health were also estimated. Macroalgae did not attach to any live coral. Coral health was not impacted by the presence of E. denticulatum regardless of origin and gene expression analyses did not indicate any additional stress in corals. Necrotic tissue on the macroalgae in areas of direct contact indicated damage inflicted by the coral. The biomass of E. denticulatum did not differ between live or dead corals but was strongly influenced by herbivory. The study indicates that E. denticulatum may not pose a strong immediate threat to healthy acroporids in the WIO region but stresses the importance to keep corals healthy and maintaining viable populations of macroalgae feeding species.
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| 13. |
- Eggertsen, Maria, et al.
(författare)
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Coral-macroalgal interactions : Herbivory and substrate type influence growth of the macroalgae Eucheuma denticulatum (N.L. Burman) Collins & Hervey, 1917 on a tropical coral reef
- 2021
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981 .- 1879-1697. ; 542
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Tidskriftsartikel (refereegranskat)abstract
- Introduced macroalgae becoming invasive may alter ecological functions and habitats in recipient ecosystems. In the Western Indian Ocean (WIO), non-native strains of the native macroalgae Eucheuma denticulatum were introduced for farming practices and consequently spread into the surrounding seascape. We investigated potential effects of non-native and native strains of this macroalgae on a branching coral. We conducted a four-factor field experiment where we examined growth and holdfast development of introduced and native E. denticulatum on live and dead branches of Acropora sp. in the presence and absence of herbivores in Unguja Island, Zanzibar. Moreover, we estimated coral and macroalgae condition by visual examinations, gene expression analyses, and photosynthetic measurements. Macroalgae did not attach to any live coral and coral condition was not impacted by the presence of E. denticulatum, regardless of geographical origin. Instead, necrotic tissue on the macroalgae in areas of direct contact with corals indicated damage inflicted by the coral. The biomass of E. denticulatum did not differ between the replicates attached to live or dead corals in the experiment, yet biomass was strongly influenced by herbivory and replicates without protection from herbivores had a significantly lower biomass. In the absence of herbivory, introduced E. denticulatum had significantly higher growth rates than native algae based on wet weight measurements. These results contribute to an increased understanding of environmental effects by the farming of a non-native strain of algae on corals and stresses the importance to maintain viable populations of macroalgal feeding fishes in such areas.
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| 14. |
- Eggertsen, Maria, 1981-, et al.
(författare)
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Different environmental variables predict distribution and cover of the introduced red seaweed Eucheuma denticulatum in two geographical locations
- 2021
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Ingår i: Biological Invasions. - : Springer. - 1387-3547 .- 1573-1464. ; 23, s. 1049-1067
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Tidskriftsartikel (refereegranskat)abstract
- In this study we examined abiotic and biotic factors that could potentially influence the presence of a non-indigenous seaweed, Eucheuma denticulatum, in two locations, one outside (Kane’ohe Bay, Hawai’i, USA) and one within (Mafia Island, Tanzania) its natural geographical range. We hypothesized that the availability of hard substrate and the amount of wave exposure would explain distribution patterns, and that higher abundance of herbivorous fishes in Tanzania would exert stronger top–down control than in Hawai’i. To address these hypotheses, we surveyed E. denticulatum in sites subjected to different environmental conditions and used generalized linear mixed models (GLMM) to identify predictors of E. denticulatum presence. We also estimated grazing intensity on E. denticulatum by surveying the type and the amount of grazing scars. Finally, we used molecular tools to distinguish between indigenous and non-indigenous strains of E. denticulatum on Mafia Island. In Kane’ohe Bay, the likelihood of finding E. denticulatum increased with wave exposure, whereas on Mafia Island, the likelihood increased with cover of coral rubble, and decreased with distance from areas of introduction (AOI), but this decrease was less pronounced in the presence of coral rubble. Grazing intensity was higher in Kane’ohe Bay than on Mafia Island. However, we still suggest that efforts to reduce non-indigenous E. denticulatum should include protection of important herbivores in both sites because of the high levels of grazing close to AOI. Moreover, we recommend that areas with hard substrate and high structural complexity should be avoided when farming non-indigenous strains of E. denticulatum.
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| 15. |
- Eggertsen, Maria, 1981-, et al.
(författare)
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Different environmental variables predict distribution of the introduced red seaweed Eucheuma denticulatum in two geographical locations
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this study we examined abiotic and biotic factors that could potentially influence the presence of a non-indigenous seaweed, Eucheuma denticulatum, in two locations, one outside (Kane’ohe Bay, Hawai’i, USA) and one within (Mafia Island, Tanzania) its natural geographical range. We hypothesized that the availability of hard substrate and the amount of wave exposure would explain distribution patterns, and that higher abundance of herbivorous fishes in Tanzania would exert stronger top-down control than in Hawai’i. To address these hypotheses, we surveyed E. denticulatum in sites subjected to different environmental conditions and used generalized linear mixed models (GLMM) to identify predictors of E. denticulatum presence. We also estimated grazing intensity on E. denticulatum by surveying the type and the amount of grazing scars. Finally, we used molecular tools to distinguish between indigenous and non-indigenous strains of E. denticulatum on Mafia Island. In Kane’ohe Bay, the likelihood of finding E. denticulatum increased with wave exposure, whereas on Mafia Island, the likelihood increased with cover of coral rubble, and decreased with distance from areas of introduction (AOI), but this decrease was less pronounced in the presence of coral rubble. Grazing intensity was higher in Kane’ohe Bay than on Mafia Island. However, we still suggest that efforts to reduce non-indigenous E. denticulatum should include protection of important herbivores in both sites, because of the high amount of grazing damages close to AOI. Moreover, we recommend that areas with hard substrate and high structural complexity should be avoided when farming non-indigenous strains of E. denticulatum.
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| 16. |
- Eggertsen, Maria, 1981-
(författare)
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Introduced and indigenous macroalgae : Ecological effects, functions and regulating factors in tropical seascapes
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tropical marine shallow-water areas are highly productive systems that promote important ecological functions and biodiversity. Stressors on these systems are intensifying due to increasing anthropogenic disturbances on multiple scales. The need to increase understanding of ongoing patterns and processes within the near-shore seascape is therefore imperative.In Tanzania in the Western Indian Ocean (WIO), introductions of South East Asian (SEA) strains of the red macroalgae Eucheuma denticulatum are made through seaweed farming, with unknown environmental consequences. Because this species occurs naturally in East Africa (EA), an ongoing introduction is difficult to assess. Also, there is limited knowledge about the extent of a possible spread and environmental factors that regulate this. Hence, ecological consequences are difficult to predict. The aims of this thesis are therefore to 1) identify and address important knowledge gaps concerning environmental effects of introduced E. denticulatum on the surrounding tropical seascape, and 2) study ecological processes and factors that influence spread, distribution and interactions with indigenous species. In doing so, the thesis also includes herbivorous fishes associated with macroalgal habitats and environmental variables influencing these fish assemblages.Paper I reviews the current scientific knowledge on introductions of SEA E. denticulatum in the WIO, and identifies knowledge gaps such as potential competition with native benthic taxa and environmental factors impacting spread. Paper II investigates environmental factors that affect the distribution and presence of SEA E. denticulatum in two geographical locations; one where E. denticulatum has turned into a nuisance and one where this is still unknown. We found that hard substrate and distance to areas of introduction best predicted SEA algal presence. Paper III examines the potential effects of E. denticulatum on corals. A field experiment showed that E. denticulatum did not induce any stress responses in corals, nor could it attach to live corals. Fish herbivory was the strongest factor controlling biomass of algae. In Paper IV and V, we focus on how seascape configuration and environmental factors influence the distribution and herbivory of reef fishes. In Paper IV, we show that macroalgal consumption was density dependent (inversely related to macroalgal cover) and that different habitats held distinct herbivorous fish communities. Moreover, Paper IV and V showed that presence and traits of macroalgae had a positive influence on the abundance of juvenile parrotfish, suggesting the potential of macroalgae to provide important nursery functions.In conclusion, this thesis indicates that negative effects by farming of SEA E. denticulatum in the WIO are minor, and might be problematic only in areas already subjected to environmental disturbances. In marine systems with high cover of live coral and healthy populations of herbivorous fishes, competition with indigenous benthic taxa is limited. Furthermore, the thesis highlights that the abundance and ontogeny of herbivorous fishes can be affected by the presence of macroalgal habitats and plant traits, suggesting macroalgal beds are key habitats with important ecological functions to be included in marine spatial planning and conservation efforts.
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| 17. |
- Eggertsen, Maria, et al.
(författare)
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Knowledge gaps and management recommendations for future paths of sustainable seaweed farming in the Western Indian Ocean
- 2021
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 50:1, s. 60-73
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Forskningsöversikt (refereegranskat)abstract
- Farming of eucheumatoid seaweeds is a widespread, promising activity and an important livelihood option in many tropical coastal areas as for example in East Africa, Western Indian Ocean (WIO). Compared to other types of aquaculture, seaweed farming has generally low impact on the environment. Nonetheless, there are potential direct or indirect negative effects of seaweed farming, such as introduction of alien species and changes in local environmental conditions. Although farming has been practiced in this region during several decades, the knowledge concerning the actual environmental impacts from faming non-native eucheumatoid haplotypes and consequently how to manage farming activities to mitigate those is highly limited. In this review, we provide a summary of the current scientific knowledge of potential direct and indirect negative environmental effects linked to eucheumatoid seaweed farming such as alterations of benthic macrophyte habitats and loss of native biodiversity. Furthermore, we highlight knowledge gaps that are of importance to address in the near future, e.g., large-scale ecosystem effects and farms as potential vectors of pathogens. We also provide a number of feasible management recommendations to be implemented for a continued development of environmentally sustainable seaweed farming practices in the WIO region, which includes spatial planning of farms to avoid sensitive areas and farming of native haplotypes of eucheumatoids instead of introduced specimens.
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| 18. |
- 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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| 19. |
- 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
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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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| 20. |
- Gullström, Martin, et al.
(författare)
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Utvärdering av videoteknik som visuell undervattensmetod för uppföljning av marina naturtyper och typiska arter : Metodsäkerhet, precision och kostnader
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Svensk naturvård är idag starkt kopplad till naturvårdsarbetet inom EU och styrs till en väsentlig del av olika direktiv. EU:s art- och habitatdirektiv är ett viktigt sådant direktiv som fokuserar på bevarande av den biologiska mångfalden. Den här rapporten presenterar en nationell studie, där det främsta syftet har varit att utvärdera undervattensvideo som visuell metod för uppföljning av marina naturtyper och typiska arter definierade i EU:s art- och habitatdirektiv. Det övergripande målet är att utveckla ett väl fungerande och harmoniserat miljöövervakningsprogram i syfte att skydda och följa upp våra kuster och hav. Projektet är utfört inom ramarna för ett samarbetsprojekt mellan Havs- och vattenmyndigheten, Naturvårdsverket och ArtDatabanken (SLU). Resultaten ligger till grund för undersökningstypen Visuella undervattensmetoder för uppföljning av marina naturtyper och typiska arter (Havs- och vattenmyndigheten manus) samt bidrar till det övergripande projektet Biogeografisk uppföljning (uppdragsavtal 2574-13). Studien utfördes under sommaren 2012 med huvudsyftet att jämföra och utvärdera data insamlat genom fyra olika fotografiska metoder: två videoanalysmetoder och två bildanalysmetoder, sinsemellan samt mot data insamlat genom dykning. Variabler som testades inkluderade taxonomisk upplösning, möjlighet att skatta olika organismers täckningsgrad med god precision samt de olika metodernas kostnadseffektivitet. För att få en helhetsbild av Sveriges kustzon så valdes fem geografiskt väl utspridda områden (från Bottenviken i norra Östersjön till Kosterarkipelagen nära den norska gränsen). Inom varje område gjordes undersökningarna på hård- respektive mjukbotten och inkluderade fem replikat per bottentyp. Resultaten visar att dykmetoden ger en högre taxonomisk upplösning än samtliga fotografiska metoder, och skattning av hela videofilmen (videoanalysmetoder) ger en högre taxonomisk upplösning än en skattning av stillbilder från filmen (bildanalysmetoder). Intressant ur ett miljöövervakningsperspektiv är att videoanalysmetoder visade likvärdig precision och replikerbarhet som dykmetoden. Kostnadsmässigt visade resultaten att video- och bildanalysmetoderna är klart fördelaktiga i jämförelse med dykning. För att skapa ett harmoniserat miljöövervakningsinstrument och för att följa upp marina naturtyper och typiska arter enligt EU:s art- och habitatdirektiv kan undervattensvideo således anses vara ett intressant och lämpligt alternativ, vilket även andra nyligen utförda studier (t.ex. Sundblad m.fl. 2013 a, b, c) indikerar.
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| 21. |
- Halling, Christina, et al.
(författare)
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HKB i Helsingborgs stad : Uppföljning av stadens arbete med hälsokonsekvensbedömningar
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna rapport redovisas resultatet av en studie som gjorts på uppdrag av Helsingborgs stad.Uppdraget består av att studera Helsingborgs stads arbete med hälsokonsekvensbedömningar(HKB) utifrån frågeställningen: Varför är det svårt att göra hälsokonsekvensbedömningar?Arbetet med HKB i Helsingborgs stad har pågått under flera år men man upplever att arbetettidvis har gått trögt. Det finns mycket teorier kring hur HKB bör genomföras men antaletpraktiska exempel är fortfarande begränsat. Även om studien innebär att Helsingborgs stadsarbete ska följas är studien ingen egentlig utvärdering i den meningen att den ska ge svar påhur väl Helsingborgs stad har lyckats med sitt HKB-arbete. Slutsatsen är att HKB innehållerett stort antal dimensioner som kan kombineras på många olika sätt och att detta ställer storakrav på pedagogisk skicklighet. Tydlighet kring syftet och förutsättningarna för HKB är avstor betydelse för att förståelse och förtroende ska skapas för metoden.
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| 22. |
- Halling, Christina, et al.
(författare)
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Introduction of Asian strains and low genetic variation in farmed seaweeds : indications for new management practices
- 2013
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 25:1, s. 89-95
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Tidskriftsartikel (refereegranskat)abstract
- Seaweed farming has a crucial role in the development of future sustainable mariculture. In the same time, spreading of introduced species or genotypes from farms may threaten local ecosystems. We analyzed a molecular marker (mitochondrial cox2-3 spacers) from cultivated and wild specimen of the widely farmed seaweeds Eucheuma and Kappaphycus, collected in Zanzibar on the African east coast where commercial farming was introduced in 1989. Genotypes of presumed Asian origin were found growing on coral reefs and drifting in seagrass meadows, indicating that genotypes introduced for farming have established successfully in the wild in Zanzibar. Only a very low number of genotypes, all of Asian origin, were found in the farms. This indicates a low accessible gene pool, which can limit the capacity for adaptation to changed conditions and disease resistance in the farming system. African genotypes were found in a few sites, showing the potential for future farming of native strains. The ecological effects of the Asian genotypes introduced to coral reefs should also be further investigated in order to evaluate the risk connected with further introductions of new foreign strains.
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| 23. |
- Halling, Christina, et al.
(författare)
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Mediebilden av Försäkringskassan 2003-2012
- 2014
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Hur påverkas förtroendet för Försäkringskassan och socialförsäkringarna av massmediernas rapportering? Forskarna Christina Halling och Björn Johnson vid Malmö Högskola har studerat mediebilden av Försäkringskassan under perioden 2003–2012. Studien visar att medierapporteringen om Försäkringskassan är omfattande och att den ökar i samband med viktiga förändringar på socialförsäkringsområdet. Rapporteringen var som störst under åren 2005 och 2007, då många förändringar genomfördes både i socialförsäkringarna och i Försäkringskassans organisation. Mest medieintresse ägnas åt sjukpenningen, som står i fokus i drygt hälften av rapporteringen. Övriga ersättningsslag fokuseras i mer begränsad omfattning. Rapporteringens vanligaste ämnen är tillämpningen av regelverket och graden av försäkringsutnyttjande, men även regelverket utformning, Försäkringskassans förmåga att fullgöra sitt uppdrag samt Försäkringskassans relation till andra offentliga aktörer tas ofta upp i rapporteringen. Grundtonen är rapporteringen är genomgående negativ. Medierna fokuserar nästan uteslutande på de delar av Försäkringskassans verksamhet som anses fungera dåligt. Den vanligaste kritiken handlar om tillämpningen av regelverket och om Försäkringskassans kompetensnivå, effektivitet och tillförlitlighet. Christina Halling och Björn Johnson menar att den mediebild som utkristalliseras är både negativ och otydlig. Det är ofta svårt som mediakonsument att avgöra i vilken utsträckning bilden stämmer överens med verkligheten och var ansvaret ligger.
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| 24. |
- Halling, Christina, 1970-
(författare)
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Seaweed Integrated Mariculture : Prospects and Constraints Towards Increased Sustainability
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Increased global demand for seafood and stagnating catches from capture fisheries contributed to the doubling of aquaculture production taking place the last decade. Expansion within the aquaculture sector is expected to persist, and by many seen as the only mean to meet future demand for seafood. Aquaculture development has however, been associated with different types of adverse environmental impacts. One such impact, originating from the flow-through behavior of modern aquaculture, and with potential negative consequence for coastal waters, is the release of nutrients. The present thesis investigates the possibilities to use seaweeds as biofilters if being integrated with fish farming. Focus is mainly on open-water fish cage cultures (e.g. salmon) and the general objective is to analyze seaweed integration in respect from its ecological and large-scale perspective. From reviewing existing literature on seaweed integration in aquaculture an imbalance between land-based and open-water culture systems becomes apparent. In land-based aquaculture several studies acknowledged the potential of using integrated seaweed as biofilters for dissolved fish waste. Such aquaculture system has also proved successful on a large-scale, both from a technical and economical perspective. However, for open water systems even basic biological, hydrological and technical understandings are lacking. This is unfortunate, as integration may presently be the only viable treatment solution for open water-cage cultures. The red seaweed Gracilaria chilensis, mainly used for agar extraction, showed high biofiltering capacity when being integrated with a salmon cage farm, with increased growth rates and nutrient content. Integrated Gracilaria growth was up to 40% (SGR 7% day-1) higher compared to monocultures and even if agar content decreased, this was more than compensated for by the higher yield and enhanced agar quality. Analysis of stable isotopes (15N/14N and 14C/13C) in seaweed thalli cultivated at different distances (e.g. 10, 30, 60, 300 m) from cages, verifies that the nutrients being incorporated by the integrated seaweed originates from the fish farm effluent. However, the continuous nutrient supply near the cages has limited effect on seaweed growth during seasons when water temperature and light overrides nutreints as limiting factors. Even if the epiphytic abundance were moderate (2-50%) compared to common bottom cultivations, epiphytes and fouling organisms may also constrain the success of open-water integration especially high infestation of bryozoa that hamper thalli growth and mussels causing the thalli to detach due to weight. The development of suitable methods for suspended seaweed cultivation is crucial for possible commercial implementation of integrated systems. Such methods must be easy manageable with respect to stocking, operation and harvesting and also be durable for open-water conditions. Spore-inoculated Gracialria ropes were found to be unsuitable for Chilean open water conditions and trials with seaweed thalli on twisted ropes showed better performance. Limited effects from integration on seaweed growth, due to seasonal variability and its spatial needs, imply that economic incentives for commercial impementation may be weak. However this could be changed if seaweeds with higher market values were cultured or if costs for nutrient abatement were internalized in the production. Seaweed integration may be one option for developing more environmentally friendly culture techniques, but this will only be confirmed from more scientific studies that include large-scale experiments.
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| 25. |
- Halling, Christina, et al.
(författare)
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The introduction of South East Asian seaweed and its ecological implications; Can native East African Eucheuma denticulatum and Kappaphycus alvarezii be a potential alternative for farming?
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The seaweed farming of eucheumoids in East Africa is solely based on introduced South East Asian (SEA) haplotypes of the carrageenophytes Eucheuma and Kappaphycus. As overexploitation of natural seaweed resources lead to a decline in harvest and export, commercial seaweed farming was started using highly productive SEA strains of the same genus introduced from the Philippines to Zanzibar in 1989. Initially, productivity was high, the sector grew rapidly and seaweed farming soon became an important livelihood. Today, the industry faces various challenges such as decreased productivity and high rates of diseases and epiphytic infestations. Continuous introduction of foreign stock for cultivation vitalization might not be the solution, as escapees of SEA Eucheuma denticulatum have been found spreading into natural environments around Zanzibar with uncertain ecological consequences. We suggest that indigenous haplotypes of E. denticulatum and Kappaphycus alvarezii should be re-evaluated for farming potential, for increasing the genetic diversity and hence resilience within stocks.This study is a first step towards a reassessment of farming potential of East African (EA) haplotypes. Molecularly identified haplotypes of E. denticulatum and K. alvarezii were tested in in-situ farming conditions in Zanzibar, and growth rates, grazing and epiphytes were compared between EA and SEA haplotypes. Results show, except for an overall decreased growth compared to previous studies, that growth rate was site dependent and that SEA Eucheuma haplotypes have a higher growth rate (1.3 ±1.8 - 3.6 ±1.9% per day) compared to EA haplotypes (0.2 ±1.0 - 2.0 ±0.4% per day). No significant differences were found in grazing rate between native and introduced Eucheuma haplotypes, while native Kappaphycus was more prone to grazing. In conclusion the farming potential for native E. denticulatum, is not rejected but underlines that there is an urgent need of continued search for native East African seaweed resources and a further identification of their desirable traits. If successful, this would enable East African seaweed industry to further expansion and secure its ecological and economical sustainability.
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| 26. |
- Levin, Lena, 1958-, et al.
(författare)
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Att integrera jämställdhet i länstransportplanering : Slutredovisning av forskningsprojektet Implementering av metod för jämställdhetskonsekvensbedömning (JKB) i svensk transportinfrastrukturplanering
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the project was to develop and test the model for Gender Equality Impact Assessment as proposed in the report Gender Equality in Traffic Planning. Principally the focus was on the Swedish national gender equality objectives of economic equality and the equal distribution of unpaid housework and provision of care. The project also aimed to identify the need for development of knowledge (of gender equality) and to develop an undergraduate training course for professionals in transportation planning.The departure of the project was taken in the objectives of gender equality in transport and the national gender equality objectives. Every fourth to fifth year a county transport plan is formed for each of the 20 regions of Sweden. These plans are the basis for investments in transport for 10–15 years in the future. The plans are used to prioritize the major transport infrastructure initiatives at the national, regional and local level.The research project was organised into five work packages, where researchers and planners collaborated. Initially the researchers analysed how gender came into account in the last two regional transport plans, and in focus groups and workshops with planners discussed their viewpoints on gender equality in the regional transportation planning. These analyses and discussions formed the basis for the two work packages with additional working sessions where a number of steps in a procedure were tested with the aim to further develop a working model for gender equality impact assessment.
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| 27. |
- Robertson-Andersson, Deborah V., et al.
(författare)
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Integrated seaweed cultivation on an abalone farm in South Africa
- 2008
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 20:5, s. 579-595
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Tidskriftsartikel (refereegranskat)abstract
- Land-based abalone aquaculture in South Africa, based on the local species Haliotis midae, started in the early 1990s and has grown rapidly in the last decade, with 13 commercial farms now producing over 850 t per annum. Over 6,000 t per annum of kelp Ecklonia maxima are now harvested for this purpose, and some kelp beds are reaching maximum sustainable limits. Research into seaweed aquacultureas feed (Ulva and some Gracilaria) for abalone started in the late 1990s on the southeast coast (where thereare no kelp beds) using abalone waste water. A growing body of evidence suggests that a mixed diet of kelp plus other seaweeds can give growth rates at least as good ascompound feed, and can improve abalone quality and reduce parasite loads. A pilot scale Ulva lactuca and abalone integrated recirculation unit using 25% recirculation was designed and built on the south west coast of South Africa using one 12,000-L abalone tank containing 13,200 15±2.5 g abalone, connected to two 3,000-L seaweed tanks containing an initial starting biomass of 10 kg of seaweed, replicated 3 times. In an 18-month period, there were no significant differences in abalone health or growth rates, sediment build up and composition, mobile macro fauna densities and species between the recirculation or the flowthroug hunits. Transfer of oxygen generated by the seaweeds to the abalone tanks was poor, resulting in the recirculated abalone tanks having lower (33%) dissolved oxygen concentrations than a comparable flow-through abalone unit. Seaweed nutrient content and specific growth rates in the units were comparable to seaweeds cultivated in fertilized effluent (SGR=3.2±3.4%.day−1; Yield=0.2±0.19 kg.m2.day−1). Indications were that at this low recirculation ratio the seaweeds in the units were nutrient limited and that there were no negative effects to the abalone being cultivated insuch a recirculation unit at this recirculation ratio.
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| 28. |
- Sundberg, Sebastian, et al.
(författare)
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Var fjärde växt och svamp är rödlistad
- 2020
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Ingår i: Svensk Botanisk Tidskrift. - 0039-646X. ; 114, s. 186-191
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 29. |
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| 30. |
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| 31. |
- Tano, Stina A., et al.
(författare)
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Extensive spread of farmed seaweeds causes a shift from native to non-native haplotypes in natural seaweed beds
- 2015
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 162:10, s. 1983-1992
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Tidskriftsartikel (refereegranskat)abstract
- Seaweed farming has been the cause of introductions of non-indigenous seaweed species and genotypes throughout the world. In Zanzibar, Tanzania, foreign genotypes of Eucheuma denticulatum were introduced for farming purposes in 1989, and in recent years a spread of non-indigenous haplotypes has been reported. The current study aimed to investigate the presence and extent of introduced and native haplotypes of E. denticulatum as well as their relative frequencies, to obtain the severity of the spread of cultivated seaweed and the current state of the native populations. The results show that all investigated sites are dominated by the introduced South-east Asian haplotypes, even where seaweed farming has never occurred. As the frequencies of East African haplotypes are remarkably low, this shows a shift from native to introduced E. denticulatum. This shift may, at least in part, be caused by earlier overharvest of natural seaweed populations, and indicates a cryptic invasion of the introduced haplotypes at the potential cost of the recovery of the native haplotype populations.
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| 32. |
- Tano, Stina A., et al.
(författare)
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Tropical seaweed beds as important habitats for juvenile fish
- 2017
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Ingår i: Marine and Freshwater Research. - 1323-1650 .- 1448-6059. ; 68:10, s. 1921-1934
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Tidskriftsartikel (refereegranskat)abstract
- Seaweed beds within tropical seascapes have received little attention as potential fish habitat, despite other vegetated habitats, such as seagrass meadows and mangroves, commonly being recognised as important nurseries for numerous fish species. In addition, studies of vegetated habitats rarely investigate fish assemblages across different macrophyte communities. Therefore, the aim of the present study was to investigate the role of tropical seaweed beds as fish habitat, particularly for juvenile fish, by comparing their fish assemblages with those of closely situated seagrass beds. Fish assemblages were assessed by visual census in belt transects, where fish were identified and their length estimated, and habitat variables were estimated for each transect. The abundance of juvenile fish in seaweed beds was twice as high as that in seagrass meadows, whereas there was no difference in total, subadult or adult fish abundance. In addition, the abundance of commercially important and coral reef-associated juveniles was higher in seaweed beds, as was fish species richness. Fish assemblages differed between habitats, with siganids being more common in seagrass meadows and juvenile Labridae and Serranidae more common in seaweed beds. These results highlight that tropical seaweed beds are important juvenile fish habitats and underscore the need to widen the view of the shallow tropical seascape.
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| 33. |
- Tano, Stina, 1983-
(författare)
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Seaweed in the tropical seascape : Importance, problems and potential
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The increasing demand for seaweed extracts has led to the introduction of non-native seaweeds for farming purposes in many tropical regions. Such intentional introductions can lead to spread of non-native seaweeds from farming areas, which can become established in and alter the dynamics of the recipient ecosystems. While tropical seaweeds are of great interest for aquaculture, and have received much attention as pests in the coral reef literature, little is known about the problems and potential of natural populations, or the role of natural seaweed beds in the tropical seascape.This thesis aims to investigate the spread of non-native genetic strains of the tropical macroalga Eucheuma denticulatum, which have been intentionally introduced for seaweed farming purposes in East Africa, and to evaluate the state of the genetically distinct but morphologically similar native populations. Additionally it aims to investigate the ecological role of seaweed beds in terms of the habitat utilization by fish and mobile invertebrate epifauna. The thesis also aims to evaluate the potential of native populations of eucheumoid seaweeds in regard to seaweed farming.The initial results showed that non-native E. denticulatum is the dominating form of wild eucheumoid, not only in areas in close proximity to seaweed farms, but also in areas where farming has never occurred, while native eucheumoids are now scarce (Paper I). The low frequency of native E. denticulatum in seaweed beds, coupled with a low occurrence of reproductive structures, indicates that the effective population size may be low, which in turn may be a threat under changing environmental conditions. These results, combined with indications that seaweeds may be declining in East Africa, illustrates the need for attaining a better understanding of the ecological role of tropical seaweed habitats. The studies on the faunal communities of seaweed beds showed that they are species rich habitats, with high abundances of juvenile fish and mobile epifauna (Paper II and III), strongly indicating that these habitats should be considered for future seascape studies and management actions. Productivity in East African seaweed farming is decreasing, and as the current cultivation is based on a single non-indigenous haplotype, a more diverse genetic base has been suggested as a means to achieve a more productive and sustainable seaweed farming. Although our results show that East African E. denticulatum has a lower growth rate than the currently used cultivar (Paper IV), the several native haplotypes that are present in wild populations illustrates that, though a demanding endeavour, there is potential for strain selection within native populations.
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| 34. |
- Tano, Stina, et al.
(författare)
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Tropical seaweed beds are important habitats for mobile invertebrate epifauna
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Marine macrophyte habitats in temperate regions are known to provide productive habitats for numerous organisms, with their abundant and diverse invertebrate epifaunal assemblages constituting important linkages between benthic primary production and higher trophic levels. While it is commonly also recognized that certain vegetated habitats in the tropics, such as seagrass meadows, can harbour diverse epifaunal assemblages and may constitute important feeding grounds to fish, little is known about the epifaunal assemblages associated with tropical seaweed beds.We investigated the abundance, biomass and taxon richness of the mobile epifaunal community of tropical East African seaweed beds, as well as the abundance of invertivorous fish, and compared it with that of closely situated seagrass meadows, to establish the ecological role of seaweed beds as habitat for epifauna as well as potential feeding grounds for fish. The results showed that seaweed beds had a higher abundance of mobile epifauna (10565±5954 vs 3742±2788 per m2) than seagrass meadows, as well as a higher biomass (35.9±46.8 vs 1.9±2.1 g per m2) and taxon richness (32.7±11.8 vs 19.1±6.3 taxa per sample). Additionally, the high abundance of invertivorous fish found in seaweed beds indicates that they act as important feeding grounds to several fish species in the region.
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| 35. |
- Tano, Stina, et al.
(författare)
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Tropical seaweed beds as important habitats for juvenile fish in an East African seascape
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Seaweed beds within tropical seascapes have received little attention as potential fish habitat despite being a prominent feature within these systems. Other tropical shallow-water habitats such as seagrass meadows and mangroves are relatively well studied and are commonly recognised as important nurseries for several species of coral reef fishes. However, there are indications that structural complexity may be more important for the juvenile fish community than the habitat type itself, which implies that other shallow habitats with high structural complexity, like seaweed beds, could also be important for fish recruitment. This study therefore investigated the role of seaweed beds as fish habitat, particularly for juveniles, in the Western Indian Ocean by comparing their fish assemblages to that of closely situated seagrass beds.Fish assemblages were assessed by visual census in belt transects, where fish were identified and their length estimated, and habitat variables were estimated for each transect.Total fish abundance was found to be similar between seaweed and seagrass habitats, while abundance of juvenile fishes was higher in seaweed beds than in seagrass meadows (25.0±13.7 vs 10.1±10.3 per transect), with no differences in subadult and adult fish abundance. Species richness was higher in seaweed beds than in seagrass meadows (11.2±3.1 vs 8.2±3.9 per transect), and seaweed beds also had higher juvenile abundance of commercially important (19.6±12.3 vs 7.6±8.9 per transect) and coral reef associated fish species (21.1±13.0 vs 3.9±5.3 per transect) than did seagrass meadows. The total fish assemblages, as well as juvenile family communities, differed between seaweed and seagrass habitat, with the fish communities of seaweed beds being less variable than those of seagrass meadows. These results highlight that tropical seaweed beds are important as juvenile fish habitats, and underscore the need to widen the view of the shallow tropical seascape and incorporate seaweed beds in management actions.
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| 36. |
- Troell, Max, et al.
(författare)
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Ecological engineering in aquaculture : use of seaweeds for removing nutrients from intensive mariculture
- 1999
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Ingår i: Journal of Applied Phycology. - Dordrecht : Kluwer. - 0921-8971 .- 1573-5176. ; 11:1, s. 89-97
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Tidskriftsartikel (refereegranskat)abstract
- Rapid scale growth of intensive mariculture systems can often lead to adverse impacts on the environment. Intensive fish and shrimp farming, being defined as throughput-based systems, have a continuous or pulse release of nutrients that adds to coastal eutrophication. As an alternative treatment solution, seaweeds can be used to clean the dissolved part of this effluent. Two examples of successfully using seaweeds as biofilters in intensive mariculture systems are discussed in this paper. The first example shows that Gracilaria co-cultivated with salmon in a tank system reached production rates as high as 48.9 kg m−2 a−1, and could remove 50% of the dissolved ammonium released by the fish in winter, increasing to 90–95% in spring. In the second example, Gracilaria cultivated on ropes near a 22-t fish cage farm, had up to 40% higher growth rate (specific growth rate of 7% d−1) compared to controls. Extrapolation of the results showed that a 1 ha Gracilaria culture gave an annual harvest of 34 t (d. wt), and assimilated 6.5% of the released dissolved nitrogen. This production and assimilation was more than twice that of a Gracilaria monoculture. By integrating seaweeds with fish farming the nutrient assimilating capacity of an area increases. With increased carrying capacity it will be possible to increase salmon cage densities before risking negative environmental effects like eutrophication and toxic algal blooms sometimes associated with the release of dissolved nutrients. The potential for using mangroves and/or seaweeds as filters for wastes from intensive shrimp pond farming is also discussed. It is concluded that such techniques, based on ecological engineering, seems promising for mitigating environmental impacts from intensive mariculture; however, continued research on this type of solution is required.
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