| 1. |
- Enge, S., et al.
(författare)
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A REVIEW OF HERBIVORE EFFECTS ON SEAWEED INVASIONS
- 2017
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Ingår i: OCEANOGRAPHY AND MARINE BIOLOGY: AN ANNUAL REVIEW, VOL 55. - BOCA RATON : Taylor and Francis. - 9781138197862 - 9781351987592 ; , s. 421-440
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Almost 300 non-native seaweeds are identified worldwide and an increasing number of these are classified as invasive with potential negative effects on the diversity and functioning of native ecosystems. Marine herbivores affect seaweed biomass and community structure in marine habitats across the globe. Consequently, herbivore-seaweed interactions are expected to be important for the establishment and invasion success of non-native seaweeds. To synthesize current knowledge of consumer effects on non-native seaweeds, we performed a meta-analysis on feeding preferences of native herbivores for non-native versus native seaweeds. Data were included from 35 studies, published from 1992-2015 and comprising 18 non-native seaweeds. Results showed that overall, native herbivores tended to prefer to feed on native rather than non-native seaweeds. Preferences were, however, variable across studies with significant differences between taxonomic and functional groups of seaweeds. In particular, filamentous red non-native seaweeds were of low palatability to native herbivores. No general feeding preferences were apparent between natives and non-natives for brown and green seaweeds, or for leathery and corticated seaweeds. In addition, we reviewed the existing studies on the effects of consumers on the performance of native and non-native seaweeds in invaded communities. This indicated that non-native seaweeds performed better than their native competitors in the presence of grazers, but in many cases had superior competitive abilities also in the absence of herbivory. To achieve a comprehensive evaluation of consumers' role in seaweed invasion success, future research should have a larger focus on manipulative community experiments, ideally on time scales that include seasonal changes and complete life cycles of the seaweeds.
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| 2. |
- Hansen, Joakim, 1978-, et al.
(författare)
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Effects of plant morphology on small-scale distribution of invertebrates
- 2010
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Ingår i: Marine Biology. - : Springer. - 0025-3162 .- 1432-1793. ; 157:10, s. 2143-2155
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Tidskriftsartikel (refereegranskat)abstract
- Habitat structure influences organism communities by mediating interactions between individuals and species, affecting abundance and species richness. We examined whether variations in the morphology of soft-bottom plants affect their function as habitat and whether complex structured plants support higher macroinvertebrate abundance and species richness. Three Baltic Sea plant species were studied, together with artificial plants resembling each species. In a field collection, we found higher invertebrate abundance on the morphologically more complex plants Myriophyllum spicatum and Chara baltica than on the structurally simpler plant Potamogeton perfoliatus. In a colonization experiment, we found the highest invertebrate abundance on artificial M. spicatum but found no difference between natural plants. Invertebrate taxon richness displayed no consistent relationship with plant structural complexity. The results imply that plant morphology influences small-scale invertebrate distribution, partly supporting the hypothesis that structurally complex plants harbour higher invertebrate abundance.
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| 3. |
- Kautsky, Hans, et al.
(författare)
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Regional och nationell miljöövervakning av vegetationsklädda havsbottnar i och kring Gaviksfjärden 2007
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- På uppdrag från Länsstyrelsen i Västernorrlands Län besöktes i augusti år 2007 totalt 23 lokaler i Gaviksfjärden och i dess närhet. Arbetet var i led med den regionala miljöövervakningen av de vegetationsklädda bottnarna i Västernorrlands Län. Av de 23 besökta lokalerna var 16 regional miljöövervakning och resterande 7 lokaler ingick i den nationella miljöövervakningen. Uppgiften var att leverera primärdata inlagda i databasprogrammet MarTrans som skulle tjäna som underlag för att ta fram metoder för regional miljöövervakning i Bottniska viken. För att kunna användas i miljöövervakning var det också viktigt att lokalernas läge dokumenterades så att framtida återbesök till exakt samma lokal var möjlig.
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| 4. |
- Kautsky, Hans, et al.
(författare)
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Vegetationsklädda bottnar i Kanholmsfjärden, Stockholms län
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med denna undersökning var att finna lämpliga lokaler och attpåbörja regional miljöövervakning av de vegetationsklädda bottnarna iKanholmsfjärden och angränsande fjärdar, Stockholms Län.Sista veckan i augusti månad år 2008 besöktes 24 lokaler i Kanholmsfjärdenmed syfte att finna cirka 8 lämpliga lokaler och påbörja regional miljöövervakningi området. Efter att ha valt fyra lokaler som besöktes år 1994(alla med beteckning HK.) valdes ytterligare 6 lokaler ut från de resterande20 lokalerna (numrerade av Länsstyrelsen från 1 till 20). Urvalet av dyklokalerskedde efter att ha videofilmat bottnarna på samtliga 20 nya lokalersom hade lagts ut av Länsstyrelsen. Syftet med videoinventeringen var att seom lämpligt substrat fanns på tillräckligt djup så att bedömningsgrundernaskriterier kunde tillämpas. På de tio slutgiltigt valda lokalerna, som befannsvara lämpliga för ett framtida regionalt miljöövervakningsprogram av devegetationsklädda bottnarna i området, genomfördes dykinventeringar enligtstandardmetod för nationell miljöövervakning.En jämförelse med år 1994 visar på en svagt positiv utveckling av devegetationsklädda bottnarna i Kanholmsfjärden och angränsande fjärdar. Påsamtliga återbesökta lokaler går blåstång djupare ner och har i allmänhetäven högre täckningsgrad än tidigare. Även röd- och brunalgerna visarsamma trend.Förekomsten och artsammansättningen på de enskilda lokalerna tyder på attområdet hyser en rik förekomst av vegetation och djur. Sammansättningenär typisk för hårda bottnar i väl ventilerade (god vattenomsättning) mellanskärgårdsområden,jämförbart med vad som finns i referensområden för dennationella miljöövervakningen i norra egentliga Östersjön (Asköområdet).Enligt bedömningsrunderna erhöll Kanholmsfjärden statusen hög. Dettaberäknades från två olika protokoll i och med att de båda dykare skattadevarje lokal oberoende av varandra.De enskilda dyklokalerna är beskrivna i detalj. Information om positioner,kompassriktning, avstånd och djup för varje lokal samt och fotografier somdokumenterar lokalens läge har bifogats och gör framtida återbesök tillexakt samma utgångsläge möjliga på decimetern när, och då utgår man frånfotografierna.Det förekommer inga större, lokala störningar i området, förutom dendagliga, tunga fartygstrafken i lederna förbi Stavsnäs – Dalarö ochSandhamn. Effekter av fartygstrafiken sågs framför allt på några nordligalokaler (kraftig stranderosion på lokal HK13, Sollenkroka, samt på lokal 10,Ängsholmen där små blåstångruskor växer på de dagligt vågspoladeklipporna cirka 0.5 m ovanför vattenlinjen).
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| 7. |
- Sagerman, Josefin, et al.
(författare)
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Divergent ecological strategies determine different impacts on community production by two successful non-native seaweeds
- 2014
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 175:3, s. 937-946
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Tidskriftsartikel (refereegranskat)abstract
- The consequences of plant introductions into ecosystems are frequently reported from terrestrial environments, but little is known about the effects on ecosystem functioning caused by non-native primary producers in marine systems. In this study we explored the effects of the invasion by the two filamentous red algae Heterosiphonia japonica and Bonnemaisonia hamifera on the primary production of seaweed communities by using single and mixed cultures of non-native and native red algae. The experiments were conducted both in the presence and absence of herbivores. Biomass production of the invaded community increased more than four times in mixed cultures with H. japonica, while introduction by B. hamifera had no significant effect. The different impact on community production could be explained by differences in life history strategies between the invaders; H. japonica grew considerably faster than the native seaweeds which directly increased the community production, while B. hamifera showed a relatively slow growth rate and therefore had no effect. From previous studies it is known that B. hamifera produces a highly deterrent, but also costly, chemical defence. The assessment of survival and growth of a native generalist herbivore further corroborated that the biomass produced by B. hamifera constitutes a very low-quality food, whereas the performance of herbivores on a diet of H. japonica was comparable to that on native algal diets. In summary, this study demonstrates that successful invaders belonging to the same functional group (filamentous red algae) may have distinctly different impacts on productivity in the recipient community, depending on their specific life history traits.
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| 8. |
- Sagerman, Josefin, et al.
(författare)
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Effects of boat traffic and mooring infrastructure on aquatic vegetation : A systematic review and meta-analysis
- 2020
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 49:2, s. 517-530
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Forskningsöversikt (refereegranskat)abstract
- Sustainable management of coastal and inland water areas requires knowledge of how tourism and recreation affects the ecosystems. Here, we present the first systematic review and meta-analysis to quantify to what extent recreational boat traffic and infrastructure for mooring affect the abundance of submerged vegetation on soft bottoms. Our systematic search yielded 25 studies containing data on effects of boat traffic, docks and mooring buoys on vegetation abundance. The abundance below docks was on average 18% of that in controls, and areas with boat traffic had on average 42% of the abundance in control areas. Mooring buoys often created scour areas without vegetation. However, the effects were variable and there were too few studies to test the reasons for this variability. We conclude that boating can cause significant declines in submerged vegetation but that informed management of boat traffic and improved design of docks and buoys can reduce negative impacts.
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| 9. |
- Sagerman, Josefin, et al.
(författare)
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Low feeding preference of native herbivores for the successful non-native seaweed Heterosiphonia japonica
- 2015
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 162:12, s. 2471-2479
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Tidskriftsartikel (refereegranskat)abstract
- Non-native seaweeds constitute a conspicuous component of many benthic coastal communities. Seaweed invaders are known to significantly affect invaded communities, but relatively little is known about the mechanisms underlying their success. In this study, we explored the feeding preferences of three generalist herbivores for the successful non-native red alga Heterosiphonia japonica and native seaweed competitors. The experiments were conducted on the Swedish Skagerrak coast (58°52′N, 11°08′E) from July to August. Additionally, chemical and physical traits of the seaweeds were assessed to mechanistically explain herbivore preferences. The results showed that H. japonica was of low preference to native herbivores and that this was most likely explained by chemical properties of the invader. We were, however, not able to determine whether the low preference was caused by deterrent metabolites or low nutritional quality. We conclude that herbivore avoidance may be important for the survival and success of H. japonica in the introduced range and that efficient means of escaping herbivory may be a common feature of invaders in seaweed communities. © 2015, Springer-Verlag Berlin Heidelberg.
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| 10. |
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| 11. |
- Sagerman, Josefin, 1980-
(författare)
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Marine seaweed invasions : Impacts and biotic resistance in native ecosystems
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Marine seaweeds constitute one of the most productive plant systems known on Earth and a rich fauna including juvenile fish and crustaceans is dependent on the habitats they form. Human influence on marine costal ecosystems has resulted in large scale changes to the abundance and distribution of species, where species introductions constitute an obvious part. The aims of this thesis were to 1) explore how non-native seaweeds impact on ecosystem functions (primary production and decomposition), and 2) study how interactions between non-native seaweeds and native communities affect invasion success. I used a combination of laboratory assays, outdoor mesocosms and field experiments.Paper I and II revealed that the impact on ecosystem functions were substantially different depending on the identity of the invader. The highly successful non-native red alga Heterosiphonia japonica had a large effect on community productivity. Due to the rapid growth of the invader, the primary production increased by more than four times in mixed species communities with the invader compared to communities with only native species. In contrast, the morphologically similar and equally successful non-native red alga Bonnemaisonia hamifera grew slowly and had no effect on community production. But B. hamifera produces a potent defense compound that deters native herbivores and reduces the growth of micro-organisms. As a direct or indirect effect of this chemical defense, the litter from B. hamifera decomposed considerably slower compared to native seaweed litter. Rapid growth and defense against predation are likely important in explaining how the two invaders have become successful in the invaded range. These results show that traits related to invasion success may determine impacts on native communities.Paper III shows that the rapidly growing invader H. japonica is avoided as food by native herbivores, which likely enables the invader to survive during colder seasons with sub-optimal growth conditions. In paper IV I found that competition from the native brown alga Fucus vesiculosus decreased growth of the non-native congener Fucus evanescens. Native herbivores caused more damage to the native competitor but it did not relieve F. evanescens from competitive pressure. Several native brown algae grow in the niche of F. evanescens, which may explain why the species only is growing sparingly in the invaded range. The results indicate that competition with native seaweeds have potential to reduce the success of non-native seaweeds in the new range.In summary, this thesis shows that non-native seaweeds differ strongly in their effect on ecosystem functions. Knowledge of which traits are present among abundant non-native species and how these traits relates to different effects may enable us to gain a better understanding of invasion impacts on native communities. The thesis also highlights that competitive interactions can be of importance for invasion success in seaweed communities.
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