| 1. |
- Näslund, Johan, et al.
(författare)
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Inventering av fisk vid Gåsefjärden i Karlskrona skärgård med nätprovfiske och eDNA
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- På uppdrag av Länsstyrelsen i Blekinge län har AquaBiota Water Research tillsammans med AERC genomfört nätprovfiske med kustöversiktsnät samt provtagning och analys av eDNA med syfte att kartlägga fisksamhället i området kring Gåsefjärden i Karlskrona skärgård.Totalt inventerades 45 stationer med nätprovfiske och 17 med eDNA, varav 16 stationer var gemensamma för båda metodikerna. Sammantaget visar inventeringarna att fisksamhället i området karaktäriseras av ett högt inslag av sötvattensfiskar, framförallt abborre och mört men i de yttre delarna är det marina inslaget tydligare med förekomst av arter som sill, skarpsill och torsk. Andel av rovfisk var relativt låg för båda metoderna Det kan indikera både dålig återväxt av rovfiskar och högt fisketryck. Totalt identifierades 30 fiskarter i det provtagna området, varav 21 arter och 3336 individer fångades med nätprovfiske. Vid de 16 stationerna där båda metodikerna användes tillsammans detekterades 16 arter med nätprovfiske och 24 arter med eDNA (samt ytterligare två artpar, ett artkomplex och två arter som saknar referenssekvens). Totalt identifierades 3 rödlistade fiskarter i hela området: ål (akut hotad), torsk (sårbar) och vimma (nära hotad).De arter som enbart detekterades med eDNA är arter som mera sällan fångas vid nätprovfisken såsom storspigg, gädda, ål och simpor. Enbart en tånglakeindivid fångades i provfisket, arten detekterades även med eDNA. Information om längd och åldersanalys från nätprovfisket visade att inga årsyngel av abborre förekom i området, vilket kan tyda på en sämre lokal reproduktionsframgång 2019.Nätprovfiske och eDNA kompletterar varandra på ett bra sätt där metoderna bidrar med olika information. Resultaten för relativ förekomst av de vanligaste medelstora arterna (mört och abborre) har en god överensstämmelse mellan metoderna. eDNA är att föredra då fiskarters förekomst i ett område är av intresse då det är fördelaktigare ur kostnadssynpunkt samt bevarandeetiska skäl. Nätprovfiske är att föredra då information om arternas fångst per nät och natt i abundans och biomassa samt längdfördelning och tillväxt är av intresse.
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| 2. |
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| 3. |
- Berkström, Charlotte, 1978-, et al.
(författare)
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Ecological connectivity and niche differentiation between two closely related fish species in the mangrove−seagrass−coral reef continuum
- 2013
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 477, s. 201-215
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Tidskriftsartikel (refereegranskat)abstract
- We aim to understand ontogenetic shifts in habitat use and feeding patterns by 2 fish species, Lutjanus fulviflamma and L. ehrenbergii, within a tropical seascape in East Africa. Stomach contents and stable isotope signatures of muscle tissues (δ13C and δ15N) were compared between and within species. Fish of all life stages and potential food items were sampled from mangrove creeks, seagrass beds, and coral reefs around Mafia Island, Tanzania. Due to similarities in morphology between species, correct species identity was confirmed using genetic barcoding (mtDNA, partial sequence of cytochrome oxidase subunit I [COI]). Stable isotope analysis in R (based on mixing models) confirmed that δ13C and δ15N values in L. fulviflamma and L. ehrenbergii reflected those of prey items caught in different habitats. Diets and mean δ13C and δ15N values of muscle tissue differed between life stages of fish, indicating ontogenetic changes in habitat and diet. L. fulviflamma and L. ehrenbergii differed in diet and δ13C and δ15N values of muscle tissue, although they overlapped in habitat use, suggesting food resource partitioning between the 2 species. Furthermore, diet overlap indexes were low between subadult species in mangrove and seagrass or coral habitats. L. fulviflamma displayed a diet shift with decreasing importance of small crustaceans in juveniles and an increasing importance of prey fishes in subadults and adults. L. ehrenbergii showed the opposite pattern. The study verifies feeding interlinkage within the mangrove-seagrass-coral reef continuum in Mafia Island by providing strong evidence of ontogenetic migration. Understanding these connections will enhance our ability to manage tropical seascapes, and highlights the need to include multiple habitats in marine protected areas.
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| 4. |
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| 5. |
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| 6. |
- Hedberg, Nils, et al.
(författare)
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Causes and consequences of spatial links between sea cage aquaculture and coral reefs in Vietnam
- 2017
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 481, s. 245-254
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Tidskriftsartikel (refereegranskat)abstract
- A majority of the sea cage farms in South East Asia are located close to coral reefs. This causes a conflict between conservation and food production since sea cage aquaculture has a number of negative impacts on coral reefs. The aim of this investigation was to assess the drivers causing the sea cage farmers to place their farms close to reefs and to examine some potential farming effects in detail i.e. usage of coral reef fish for grow out farming and feed. For some 3500 Vietnamese fish and lobster farms, we measured; the distance to the closest coastal city (proxy for infrastructure access), satellite derived Chl a (proxy for water quality), wind fetch, and the adjacent coastal slope and elevation. We also performed 159 semi-structured interviews with fish and lobster cage farmers from three regions in Vietnam. The interviews revealed that the choice of farming site is mainly determined by access to infrastructure, wind and wave shelter, and water quality. Although the farmers used coral reef services, e.g. coral reef derived seedlings, they were in general not aware of coral reef presence or did not find it important for selection of site. Both coral reefs and sea cage farms were found close to steep rocky coasts, which are favorable for corals, and provide sufficient depth for sea cages. Sea cages were always found on the leeward side of the coast where the wind fetch is low enough for the floating farms and their inhabitants. Most of the farms were located within 20 km from a coastal city confirming the importance of access to infrastructure. With few exceptions, sea cage farms were located in areas with good water quality, where also coral reefs are present. The study showed that several of the coral associated species groups farmed were dependent on wild caught seedlings and that 22% of the feed used at farms was trashfish of coral reef associated species. We consider the spatial correlation between sea cage farms and coral reefs as circumstantial and suggest that shared environmental preferences explain the farm distribution pattern, rather than access to ecosystem services provided by the nearby reef itself. We found no evidence that it is necessary for sea cage farms to be located near coral reefs and strongly recommend that sea cages are moved further away from coral reefs, but to areas still providing clear water, shelter and access to infrastructure.
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| 7. |
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| 8. |
- Hedberg, Nils, et al.
(författare)
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Spatial correlation and potential conflicts between sea cage farms and coral reefs in South East Asia
- 2015
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 448, s. 418-426
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Tidskriftsartikel (refereegranskat)abstract
- In the South China and Java Seas, cage farming is a recent regional activity, which since the year 2000 has experienced an annual growth of 29%. The region holds the highest diversity of marine life, which is partly or completely dependent on coral reefs. The increasingly growing coastal human population in the area relies on ecosystem goods and services provided by the reefs that are threatened by anthropogenic activities. Sea cage farming is one of the stressors negatively impacting coral reefs by being point sources of nutrients and other effluents. To date no systematic information is available on the physical location of marine farms in relation to the coral reefs. Little is known about the distance where impact from the farms can be detected on nearby coral reefs. The present survey aimed to fill this gap by assessing to what extent marine cage farms in South East Asia are placed in the vicinity of the reefs and at which distance stress indicators from the farms are observed. We used Google Earth satellite images to investigate the extension and spatial distribution of sea cage aquaculture in relation to the presence of coral reefs. The stress indicators were locally assessed in Central Vietnam by recording turf algal overgrowth, coral mortality, live coral and branching coral cover at increasing distances from the farms. We found that 90% of sea cage farms throughout the region clustered closer than 5 km from coral reefs and 50% of them closer than 1 km from reefs. In Taiwan, 71% of the cages were located within 100m from a reef. This pattern is nonrandom and could not be explained by the natural distribution of coral reefs; only 5% of the Vietnamese coast harbors coral reefs, and sea cage farms are present in these areas only. This indicates that the farms require similar conditions as the reefs including clear and shallow waters and protection against storms and wave action. We found that turf algal overgrowth decreased at 287 m +/- 54 m, dead coral at 1446m +/- 154 m, live coral cover increased at 566 +/- 221 m and branching corals increased at 867 m +/- 140 m from the cage farms. We conclude that proximity to coral reefs should be considered when planning future developments of sea cage aquaculture, and recommend that distances of at least 1.5 km should be kept. Statement of relevance: Consider coral reefs when planning sea cage aquaculture site.
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| 9. |
- Hellström, Ann Micaela, et al.
(författare)
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Robustness of size measurements in soft corals
- 2011
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Ingår i: Coral reefs (Print). - : Springer Science and Business Media LLC. - 0722-4028 .- 1432-0975. ; 30:3, s. 787-790
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Tidskriftsartikel (refereegranskat)abstract
- Accurate colony size measurement in soft-bodied sessile aquatic invertebrates is more difficult than in hard corals because of the variable state of the hydroskeleton in the former. The present study examined variation in colony height, oral disc diameter and basal circumference in three species of soft coral of different morphological types (Sarcophyton elegans, Sinularia flexibilis and Dendronephthya sp.) over a 24-h period. Individual colonies changed considerably in size over this period. Coefficients of variation for height measurements and oral disc were 0.09–0.36 and 0.08–0.28, respectively, but were only 0.02–0.09 for basal circumference, in all three species. Measurements of basal circumference in the field showed the highest correlation with colony biomass (volume after water displacement in formalin) confirming basal circumference to be a sound measure of colony size in repeated measurement studies.
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| 10. |
- Hellström, Micaela, et al.
(författare)
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LifeDNAquatic: Riktlinjer för optimal hantering och analys av akvatiskt eDNA som verktyg inom svensk miljöövervakning
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Naturvårdsverket och Havs- och vattenmyndigheten i Sverige beviljade åtta forskningsprojekt 2018 för att undersöka hur eDNA kan användas som verktyg inom den svenska miljöövervakningen. Projektet LifeDNAquatic, presenteras i denna rapport.De tre första arbetspaketen inom projektet resulterade i två tekniska rapporter som behandlar fältplanering, provtagning i fält och olika sorters fältutrustning. Riktlinjer för laboratorier specifika för eDNA och extraktionsmetoder diskuteras.Sju undersökningar (5–11) utfördes för att validera eDNA som metod och för att utröna användbarheten av eDNA-flerartsanalyser som verktyg inom miljöövervakningen. Mer än 460 eDNA-prover samlades in under undersökningstiden.Delundersökning 5: Går det att jämföra artförekomster baserade på flerartsanalyser som kommer från helt olika eDNA-laboratorier? En jämförande undersökningutfördes där fem laboratorier deltog för att jämföra fiskdetektion från samma vatten. Artanalyserna från de olika laboratorierna visade förvånansvärt liknande resultat. Detta innebär att resultat från olika eDNA-utövare är jämförbara och att metoden är tillförlitlig.Delundersökning 6: Är resultaten av eDNA-analyser jämförbara då prover bevaras i olika konserveringsvätskor över tid? Analysen visade att prover som bevaras under kort tid oberoende av konservering uppvisar samma resultat. Då proverna bevaras mer än tre månader är resultaten jämförbara bara då proverna bevarats i etanol.Delundersökning 7: Går det att analysera filter som bevarats i etanol i 1,5 år? eDNA-prover som bevarats i etanol i kylskåp i 1,5 år visar att detektionsprecisionen av den biologiska mångfalden är lika hög oberoende om proverna bevarats kort eller lång tid.Delundersökning 8: Hur påverkar provtagningsdesign slutresultaten av en undersökning? Går det att undersöka artnärvaro i biflöden genom att enbart analyseraprover från dess huvudflöde? Slutsatsen från detta är att en genomtänkt provtagningsdesign och val av lokaler kan spara både tid och resurser då eDNA används som metodinom miljöövervakningen. För mera finskalig utbredning av arter bör flera lokaler inventeras. Vidare ger prover från huvudflöde inte information om artnärvaro i biflöden. Månatliga prover ger en mer korrekt relativ biomassa av fiskarter eftersom mjölke-eDNA då kan uteslutas från analysen.Delundersökning 9: Kan man utröna säsongsvariationer med eDNA över ett år? Hur många prover behöver samlas in på de enskilda lokalerna? Från detta arbetspaketdrar vi slutsatsen att prov som tas från samma lokal månadsvis under ett år är ett mycket kraftfullt verktyg för artinventeringar eftersom både arternas inbördes dominans i fisksamhället samt reproduktionstider kan fastslås. Antal prover som behöver samlas in vid en provpunkt framgår av undersökningen.Delundersökning 10: Hur skiljer sig resultatet mellan eDNA och nät-/elfisken? eDNA i marin miljö detekterade 24 fiskarter jämfört med 15 arter i nätfisket. eDNA i rinnande vatten detekterade 1,2 till 4,7 gånger fler arter än sammanslagna historiska elfiskedata.Delundersökning 11: Är eDNA kostnadseffektivt i relation till traditionella metoder? Flera olika demonstrationsprojekt visar att eDNA som metod är kostnadseffektivt i relation till traditionella inventeringsmetoder. Skillnaden beror på tidsåtgången i fält, som är betydligt högre för traditionella metoder jämfört med eDNA.
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| 11. |
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| 12. |
- Hellström, Micaela, et al.
(författare)
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Multiple spawning events and sexual reproduction in the octocoral Sarcophyton elegans (Cnidaria: Alcyonacea) on Lizard Island, Great Barrier Reef
- 2010
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 157:2, s. 383-392
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Tidskriftsartikel (refereegranskat)abstract
- Sarcophyton elegans is a common symbiotic (zooxanthellate) octocoral species in the shallow waters of the Great Barrier Reef (GBR). Study of a population at Lizard Island (14°40′S, 145°28′E) on the GBR from October 1991 to January 1994 revealed that, as is typical of tropical alcyonarian corals, S. elegans is a gonochoric broadcast spawner with a 1:1 sex ratio. Sexual reproduction was closely correlated with colony size, with first reproduction at 13-cm basal stalk circumference for females and 12 cm for males. Oogenesis took 19–24 months, with a new cycle commencing every year, and spermatogenesis took 10–12 months. The majority of gametes were released during the annual austral mass coral spawning event after the full moon in November, but gametes were also released after the full moon in each month between August and February. All autozooid polyps participated in reproduction, but those at the outer edge of a colony released their gametes first. During subsequent months, the polyps closer to the center of the colony released their gametes. This is a novel strategy of gamete release, reported here for the first time, which accommodates the demands of feeding and reproduction in a different way than other corals where individual polyps have separate feeding or reproductive roles. Colonies upstream in the prevailing current spawned up to 1 month earlier than those downstream and ceased 1 month earlier. The mechanism controlling this spatial differentiation in spawning time, repeatedly observed over three seasons, is unknown. Sarcophyton elegans appears to have a dual strategy of providing protection for its gametes by releasing most of them concurrently with the single, annual mass spawning of a large number of cnidarians, while also hedging its bets by individual colonies spawning a fraction of their gametes over an extended period of 6 months.
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| 13. |
- Hellström, Micaela, 1965-
(författare)
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Sex and symbionts : New discoveries in local and regional patterns of coral ecology and reproduction
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Coral reefs belong to the most diverse and the most threatened ecosystems on earth. Anthropogenic stressors and climate change have led to mortalities at levels unprecedented in modern times. The aims of this thesis are to investigate aspects of the corals’ ability to reproduce, disperse, adapt and survive. Papers I-III study reproduction in a common soft coral species, Sarcophyton elegans, with previously unknown reproductive modes. Paper IV investigates genetic distribution of coral-symbiont associations in Galaxea fascicularis focusing on adaptation to the environment along the coastline of Vietnam. Sarcophyton elegans is a gonochoric broadcast spawner with a 1:1 sex ratio. Reproduction is strictly size dependent. Oogenesis takes 19-24 months, with a new cycle commencing every year. Spermatogenesis takes 10-12 months. The majority of gametes were released during the annual austral mass spawning event after full moon in November, but spawning also occur between August and February. The polyps at the outer edge of the colonies released their gametes first, followed by polyps situated closer to the center during subsequent months. Colonies upstream in the prevailing current spawn earlier than those downstream. The colonies were arranged in clusters of alternating males and females, which spawned simultaneously and were of the same genotype. Fission and buddying is a common mode to expand locally. Additionally, females undergoing fission divided into the most fecund size classes. The G. fascicularis and their associated symbionts were not genetically coupled to each other but to environmental factors. The host displayed an inshore-offshore zonation, with higher diversity offshore. The D1a symbiont exhibited an inshore- offshore zonation. In contrast; the 5 different C symbiont types showed a latitudinal distribution gradient, which shifted in dominance north to south. The study highlights the importance of protecting resilient coral and algal genotypes in stressed areas and the need to understand reproductive modes for coral conservation.
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| 14. |
- Hellström, Micaela, et al.
(författare)
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Symbiodinium spp. diversity in a single host species, Galaxea fascicularis, Vietnam : Impact of environmental factors, host traits, and diversity hot spots
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We determined the distribution of zooxanthellate ITS2 types within one broadcast spawning coral species,Galaxea fascicularis with horizontal symbiont uptake, in both inshore and offshore reef habitats over a 3200 km range along the coast of Vietnam, covering 11 degrees of latitude. Host traits (mtDNA genotype) and environmental factors (visibility, sea surface temperatures and Chlorophyll a derived from satellite data, regional measures of coral species diversity and distance from land (inshore/offshore)) were measured to test whether symbiont type distribution was determined by host characteristics or by environmental factors. The G. fascicularis and their associated symbionts were not genetically coupled to each other but to environmental factors The host displayed an inshore-offshore zonation, with higher diversity offshore. The D1a symbiont exhibited an inshore- offshore zonation. In contrast; the 5 different C symbiont types showed a latitudinal distribution gradient, which shifted in dominance north to south. We found regional differences in symbiont type; these were related to environmental differences and not to genetic characteristics in the coral G. fascicularis.
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| 15. |
- Spens, Johan, et al.
(författare)
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Comparison of capture and storage methods for aqueous macrobial eDNA using an optimized extraction protocol : advantage of enclosed filter
- 2017
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Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 8:5, s. 635-645
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous environmental DNA (eDNA) is an emerging efficient non-invasive tool for species inventory studies. To maximize performance of downstream quantitative PCR (qPCR) and next-generation sequencing (NGS) applications, quality and quantity of the starting material is crucial, calling for optimized capture, storage and extraction techniques of eDNA. Previous comparative studies for eDNA capture/storage have tested precipitation and open' filters. However, practical enclosed' filters which reduce unnecessary handling have not been included. Here, we fill this gap by comparing a filter capsule (Sterivex-GP polyethersulfone, pore size 022m, hereafter called SX) with commonly used methods. Our experimental set-up, covering altogether 41 treatments combining capture by precipitation or filtration with different preservation techniques and storage times, sampled one single lake (and a fish-free control pond). We selected documented capture methods that have successfully targeted a wide range of fauna. The eDNA was extracted using an optimized protocol modified from the DNeasy((R)) Blood & Tissue kit (Qiagen). We measured total eDNA concentrations and Cq-values (cycles used for DNA quantification by qPCR) to target specific mtDNA cytochrome b (cyt b) sequences in two local keystone fish species. SX yielded higher amounts of total eDNA along with lower Cq-values than polycarbonate track-etched filters (PCTE), glass fibre filters (GF) or ethanol precipitation (EP). SX also generated lower Cq-values than cellulose nitrate filters (CN) for one of the target species. DNA integrity of SX samples did not decrease significantly after 2weeks of storage in contrast to GF and PCTE. Adding preservative before storage improved SX results. In conclusion, we recommend SX filters (originally designed for filtering micro-organisms) as an efficient capture method for sampling macrobial eDNA. Ethanol or Longmire's buffer preservation of SX immediately after filtration is recommended. Preserved SX capsules may be stored at room temperature for at least 2weeks without significant degradation. Reduced handling and less exposure to outside stress compared with other filters may contribute to better eDNA results. SX capsules are easily transported and enable eDNA sampling in remote and harsh field conditions as samples can be filtered/preserved on site.
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