| 1. |
- 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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| 2. |
- 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
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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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| 3. |
- Florén, Karl, et al.
(författare)
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Kartering av bentiska naturvärden i Bottniska Viken
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Som en del i Havs- och vattenmyndighetens kartläggning av havsbotten längs svenska kusten har bentiska ekosystemkomponenter och naturvärden karterats på översiktlig nivå i Bottniska viken. Karteringen utfördes med hjälp av rumslig modellering baserad dels på befintliga biologiska fältdata, dels på biologiska data från kompletterande undersökningar samt på heltäckande lager över fysiska, kemiska och antropogena variabler. Totalt skapades 17 heltäckande kartor över vegetation och epifauna, sju kartor över infauna samt en karta över sammanlagda bentiska naturvärden.
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| 4. |
- Florén, Karl, et al.
(författare)
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Kartering av marina naturvärden i Västerbottens län
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Som en del i Havs- och vattenmyndighetens kartläggning av havsbotten längs svenska kusten har bentiska ekosystemkomponenter och naturvärden karterats i hög upplösning i Västerbottens län. Karteringen utfördes med hjälp av rumslig modellering baserad dels på befintliga biologiska fältdata, dels på biologiska data från kompletterande undersökningar samt på heltäckande lager över fysiska, kemiska och antropogena variabler. Totalt skapades 11 heltäckande kartor över vegetation och epifauna, fem kartor över infauna, en karta över sikyngel, en karta över Helcom Underwater Biotopes (HUB) samt en karta över bentiska naturvärden.
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| 5. |
- Fulton, Christopher J., et al.
(författare)
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Form and function of tropical macroalgal reefs in the Anthropocene
- 2019
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 33:6, s. 989-999
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Forskningsöversikt (refereegranskat)abstract
- Tropical reefs have been subjected to a range of anthropogenic pressures such as global climate change, overfishing and eutrophication that have raised questions about the prominence of macroalgae on tropical reefs, whether they pose a threat to biodiversity, and how they may influence the function of tropical marine ecosystems. We synthesise current understanding of the structure and function of tropical macroalgal reefs and how they may support various ecosystem goods and services. We then forecast how key stressors may alter the role of macroalgal reefs in tropical seascapes of the Anthropocene. High levels of primary productivity from tropical canopy macroalgae, which rivals that of other key producers (e.g., corals and turf algae), can be widely dispersed across tropical seascapes to provide a boost of secondary productivity in a range of biomes that include coral reefs, and support periodic harvests of macroalgal biomass for industrial and agricultural uses. Complex macroalgal reefs that comprise a mixture of canopy and understorey taxa can also provide key habitats for a diverse community of epifauna, as well as juvenile and adult fishes that are the basis for important tropical fisheries. Key macroalgal taxa (e.g., Sargassum) that form complex macroalgal reefs are likely to be sensitive to future climate change. Increases in maximum sea temperature, in particular, could depress biomass production and/or drive phenological shifts in canopy formation that will affect their capacity to support tropical marine ecosystems. Macroalgal reefs can support a suite of tropical marine ecosystem functions when embedded within an interconnected mosaic of habitat types. Habitat connectivity is, therefore, essential if we are to maintain tropical marine biodiversity alongside key ecosystem goods and services. Consequently, complex macroalgal reefs should be treated as a key ecological asset in strategies for the conservation and management of diverse tropical seascapes. A plain language summary is available for this article.
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| 6. |
- 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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| 7. |
- 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?
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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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| 8. |
- 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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| 9. |
- 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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| 10. |
- 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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| 11. |
- Tano, Stina, et al.
(författare)
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Sjöfartens rumsliga behov och miljöpåverkan i Kattegatt : fördjupat underlag för svensk havsplanering
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- AquaBiota Water Research och SSPA genomfört en utredning med syfte att ge underlag till Havs- och vattenmyndighetens havsplaneringsuppdrag. Det i myndighetens planskiss föreslagna, förhållandevis rumsligt breda, användningsområdet för sjöfart i Kattegatt utvärderas utifrån både sjöfartens behov och utifrån naturhänsyn. Utredningen analyserar den nuvarande trafiksituationen i avseende på fartygstrafikens karaktär och jämför denna med den förväntade fartygstrafiken efter genomförandet av föreslagna ruttsystemen i Kattegatt. De nya ruttsystemen syftar till ökad sjösäkerhet, viket uppnås genom att trafiken till/från Öresund respektive Stora Bält separeras genom att Öresundstrafiken hänvisas till en ny rutt närmare svenska kusten och genom att nord- och sydgående trafikflöden separeras i respektive led. Distansen i den nya rutten för trafik mot Öresund skiljer endast lite mot den idag nyttjade, men väntas ändå medföra en viss minskning av bränsleförbrukningen för denna trafik.Rapporten beskriver också de kartlagda naturvärdena i Kattegatt, med fokus på de värdefulla Natura 2000-områden som ligger inom eller i nära anslutning till farleder, trafiksepareringszoner och . Sjöfartens potentiella påverkan på naturmiljöerna inom de berörda områdena identifieras, och de påverkansfaktorer som bedöms vara relevanta diskuteras.Resultaten indikerar att bredden som anges för i havsplanen i huvudsak bedöms vara väl dimensionerad och lokaliserad ursjösäkerhetssynpunkt, liksom ifråga om sjötrafikintressen. Justeringar rekommenderas dock för att anpassa området till de bredder och lokaliseringar som definieras av föreslagna nya trafiksepareringar, djupvattenleder och rekommenderade rutter. Föreslagna nya ruttsystem bedöms bidra till ökad sjösäkerhet och trafikbilden bedöms bli mer samlad med mindre trafik utanför farledsstråken. De farledsytor som definieras av de nya ruttsystemen bedöms därför också vara lämpliga för dimensionering av bredden påEftersom flertalet marina naturvärden i området bedöms vara mycket sårbara och svårsanerade vid oljeutsläpp, anses en ökad sjösäkerhet vara viktig även ur naturvårdshänseende. Då det finns indikationer på att sjöfart kan påverka tumlare, och även andra organismer i havsområdet, är det eftersträvansvärt att bredden på inte överstiger den bredd som krävs för en bibehållen sjösäkerhet. I övrigt rekommenderas att utreda möjligheterna att minska buller från sjöfarten i områden som anses särskilt känsliga för bullerpåverkan, och att följa upp värdefulla områden som tidigare inventerats i Kattegatt för att kunna utvärdera konsekvenserna av den förändrade fartygstrafikens påverkan. Utöver detta skulle en mer ingående analys behövas för att fastslå om de nya rutterna riskerar att leda till bottenpåverkan, och det är även av intresse att utvärdera om trålfiske inom de aktuella rutterna kan utgöra en risk för sjösäkerheten.
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| 12. |
- Tano, Stina, et al.
(författare)
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Sjötrafikbelastning på Salvorev, norr om Gotland
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- AquaBiota Water Research och SSPA har, genomfört en utredning som syftar till att utreda de prognosticerade trafikförändringarna i Salvorevsområdet, samt sjöfartens konsekvenser för naturvärdena vid Salvorev, norr om Gotland.Utredningen avser specifikt de förändringar som förväntas då rutten mellan Hoburgs bank och Gotland inte längre används. Utredningen innefattar en beskrivning av nuvarande fartygstrafik i området samt en bedömning av hur sjöfarten över Salvorev skulle öka om fartyg framöver omdirigeras från rutten vid Hoburgs bank till leden väster om Gotland. Därtill görs en kvalitativ konsekvensbedömning med iakttagande av hur sjöfartens trafikmönster påverkar Natura 2000-områden, skyddsvärda habitat samt för området viktiga arter som alfågel och gråsäl.Resultaten visar att dagens sjötrafik vid Salvorev utgörs av ca 2 100 årliga passager, vilka domineras av passager inom den dubbelriktade farledskorridoren Two-way Route Salvorev, vilken även korsas av linjetrafik mellan Nynäshamn och Ventspils, Lettland. Det finns indikationer på att nuvarande trafik kan påverka naturvärdena i området negativt, men det är svårt att fastslå i vilken omfattning. Den förhöjda risken för oljeutsläpp i området illustrerar en ökad riskbild för känsliga naturvärden såsom övervintringsområden för alfågel, fartygspassager kan störa sjöfågel, och undervattensbuller kan till exempel ge negativa effekter på ung fisk. Vid en omdirigering kan stora delar av den fartygstrafik som i dagsläget trafikerar rutten sydost om Gotland komma att adderas till den redan existerande trafiken vid Salvorev. Detta innebär en mycket omfattande ökning i antalet passager (16 000 årliga passager), en ökning av antalet fartyg med större djupgående, samt en möjlig ökning av fartygens medelhastighet i området. Sannolikheten för grundstötnings- och kollisionsolyckor antas öka med ökad passagefrekvens och ökad trafik med lastade oljetankfartyg medför risker för stora utsläpp med allvarliga miljökonsekvenser. Detta utgör också den huvudsakligt ökade risken för naturvärdena i området, då flertalet arter och biotoper bedöms som sårbara för oljeutsläpp. Särskilt för sjöfågel, som även kan komma att påverkas negativt av störningar uppkomna av det ökade antalet fartygspassager, bedöms detta utgöra en betydligt ökad risk för områdets naturvärden i jämförelse med dagens trafikläge. Vattendjupet är ungefär samma vid passagen förbi Salvorev som mellan Gotland och Hoburgs bank, men den anvisade dubbelriktade farledszonen är bara omkring hälften så bred som passagen vid Hoburg. Den förtätade trafikbild som kan uppstå vid Salvorev kompliceras även av det idag diagonalt korsande stråket med trafik mellan Nynäshamn och Ventspils. Om de beskrivna omdirigeringsåtgärderna ska genomföras, rekommenderas därför att sjösäkerhetsmässiga frågor om bredden på farledszonen vid Salvorev och eventuella behov av förändrade routing-åtgärder utredas närmare.
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| 13. |
- Tano, Stina, et al.
(författare)
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Tropical seaweed beds are important habitats for mobile invertebrate epifauna
- 2016
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 183, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Marine macrophyte habitats in temperate regions 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 (>= 1 mm) of tropical East African seaweed beds, as well as the abundance of invertivorous fishes, 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 (mean SD: 10,600 +/- 6000 vs 3700 +/- 2800 per m(2)) than seagrass meadows, as well as a higher invertebrate biomass (35.9 +/- 46.8 vs 1.9 +/- 2.1 g per m(2)) and taxon richness (32.7 +/- 11.8 vs 19.1 +/- 6.3 taxa per sample), despite having a lower macrophyte biomass. Additionally, the high abundance of invertivorous fishes found in seaweed beds indicates that they act as important feeding grounds to several fish species in the region.
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| 14. |
- 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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| 15. |
- 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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| 16. |
- Tano, Stina, et al.
(författare)
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Undersökning av undervattensmiljöer vid Klints bank
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I augusti 2017 genomfördes på uppdrag av Länsstyrelsen i Gotlands län en undersökning av undervattensmiljön på 50 stationer inom 5 olika djupintervall vid Klints Bank. Huvuddelen av undersökningen utfördes med dropvideo, och därutöver gjordes även bottenhugg och CTD-profiler.Klints bank är ett grundområde i utsjön, och miljön är mycket exponerad. Bottensubstratet dominerades av sand, grus och småsten, med inslag av stor sten och block. De grövre substratklasserna som stor sten och block var vanligare på grundare djup. Antalet förekommande arter och organismer var mycket begränsat och de dominerande organismerna var blåmusslor och hydroider. På 40% av stationerna förekom blåmusselbankar, vilka var vanligare i de grundare områdena.
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| 17. |
- 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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