| 1. |
- Engkvist, Ola, et al.
(author)
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On the relation between retention indexes and the interaction between the solute and the column in gas-liquid chromatography
- 1996
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In: Journal of chemical information and computer sciences. - : American Chemical Society (ACS). - 0095-2338 .- 1520-5142. ; 36:6, s. 1153-1161
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Journal article (peer-reviewed)abstract
- Gas-liquid chromatography retention indexes for organic molecules are determined by the interaction between the molecule and the column liquid phase. In this article, a model for calculating the interaction energy between a molecule and a dielectric wall is developed. The model is at least to our knowledge the first attempt to predict retention indexes from the interaction between the molecules and the column. This approach to predict retention indexes is radically different from methods proposed before. Earlier predictions of the retention indexes have been done by a large number of descriptors, which were Linearly correlated to the retention indexes. The developed model has been tested for polycyclic aromatic hydrocarbons mainly with a molecular weight of 302. For the molecules with MW 302 the obtained correlation coefficient is 0.92. A somewhat simpler model is used to fit PAH with different MWs. A correlation coefficient of 0.998 is obtained if the retention indexes were fitted to the logarithm of the interaction energies between the PAHs and the column.
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| 2. |
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| 3. |
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| 4. |
- Engkvist, Roland
(author)
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Grazing in Macroalgae Communities of the Baltic Sea
- 2003
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Doctoral thesis (other academic/artistic)abstract
- Fucus vesiculosus and Fucus serratus are the only large, structuring perennial brown macroalgae in the low salinity waters of the Swedish coast of the Baltic Proper. Since the 1970s there are reports of declining Fucus vesiculosus stands from several locations around the Baltic Proper, but also indications of recoveries e.g. in Finland, in the Askö area of the northern Baltic proper and in the south east coast of Sweden. There are probably several causes for these changes. This thesis focuses on how, among biological and other factors, grazing may be the proximate factor to structure the rocky phytal zone of the Baltic Sea. Destructive effects on F. vesiculosus may be connected to extreme densities of grazers. In a field survey large densities of the potential mesograzer Idotea baltica correlated positively with grazing injuries on and reduced depth penetration of Fucus vesiculosus. In a grazing experiment biomass of F. vesiculosus was halved within two weeks at a grazer density found in the field (80 I. baltica per 100 g of Fucus wet weight). In a second survey large numbers of the gastropods Theodoxus fluviatilis and Lymnaea peregra coincided with unsuccessful recruitment of F. vesiculosus. In an experiment these gastropods grazed germlings of F. vesiculosus up to sizes of 0.8 and 1.0 mm respectively. Abundances of gastropods were highest in autumn, indicating that autumn reproductive F. vesiculosus might be more influenced than spring reproductive F. vesiculosus as the latter would have surpassed the critical size in autumn. Grazing may be modified by environmental factors. Comparatively small densities of Theodoxus fluviatilis correlated positively with abundances of Fucus vesiculosus and negatively with abundances of filamentous algae. Grazing effects advantageous to F. vesiculosus were tested in a field experiment with manipulation of grazers, nutrients and propagules of filamentous algae. At low nutrient loads grazers tended to clear the substrate from filamentous algae and strengthen the competitive ability of F. vesiculosus. At high nutrient loads the grazers could not prevent dominance of filamentous algae with detrimental effects to F. vesiculosus. Physical factors like wave-action may also modify grazing effects. In a wave-exposed coastline with mixed stands of perennial brown algae and frequent occurrences of grazing isopods, F. vesiculosus declined faster than F. serratus. In an experiment F. vesiculosus was more heavily grazed than F. serratus, but only at intense water motion. Thus F. serratus seem to have a competitive advantage to F. vesiculosus in wave exposed coasts where severe grazing occurs. The fact that the grazer I. baltica often has been connected with F. vesiculosus, might indicate that this animal would be dependent on F. vesiculosus as habitat and/or food. In a wave-exposed habitat on the eastern coast of Öland, probably earlier dominated by F. vesiculosus but now holding discrete patches of either red algae {Polysiphonia fucoides) or saw-wrack (F. serratus) I. baltica used both species as habitat and food. In addition to the two macroalgae faecal pellets contained 30-40 % microalgae, indicating that mixed diets may be important for this species. In monitoring programs of rocky bottom communities fixed sites may be revisited on a yearly bases to estimate the development of the community. There is an underlying assumption that the observations at a fixed site are representative to surrounding areas. This assumption was tested along a 350 km coastline in SE Sweden. 18 years of observations were evaluated and compared to complementary sites. Within areas of similar wave exposure there was good agreement between fixed sites and surrounding areas. When all fixed sites within wave-protected areas were analysed together for long-term trends, there was an agreement in development between sites över the whole geographic area. The Fucus community increased its distribution during the 1980s, decreased during the early ]990s (probably from grazing as described above), to increase again in 2000-2001, that is an oscillating pattern is suggested. In wave-exposed sites, along a 100 km coastline, the F. vesiculosus stands were destroyed, seemingly by grazing as described above, around 1992-1994, with no signs of recovery as late as in 2002. The results are discussed in the context of grazing, regulation of grazing by predation, eutrophication and physical factors. The importance of the lack of fish predators is suggested for further research.
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| 5. |
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| 6. |
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| 7. |
- Engkvist, Roland, et al.
(author)
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Utbredning av blås- och sågtång i Kalmar och och Blekinge län: utvärdering och kvalitetssäkring av regionala data
- 2002
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Reports (other academic/artistic)abstract
- Tångsamhällena i sydöstra Sverige följs inom den regionala recipientkontrollen genomregelbundna besök av dykare på ett antal fasta lokaler. I Kalmar län besöks lokalerna en gångom året sedan 1980-talets början, i Blekinge län minst vartannat år sedan 1990. År 2000återbesöktes ett stort antal extra lokaler som tidigare endast besökts vid enstaka tillfällen isamband med andra miljöundersökningar. Målet med denna rapport är att beskrivautvecklingen av blås- och sågtångens utbredning i länen samt att utvärdera om data frånrecipientkontrollen är representativ för omgivande kustområden.
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| 8. |
- Engstedt, Olof, 1980-, et al.
(author)
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Elemental fingerprinting in otoliths reveals natal homing of anadromous Baltic Sea pike (Esox lucius L.)
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Other publication (other academic/artistic)abstract
- Northern pike (Esox lucius) inhabit the coastal areas of the Baltic Sea. A large part of the fishes show anadromous behaviour and spawn in streams and rivers but spend most of the time foraging in the sea. We examined spawning migration in four streams in the southwest part of the Baltic, situated within a radius of 50 km. Using juvenile pike in the streams as references, otolith analysis by microPIXE revealed unique elemental patterns (Sr, Zn, Br, Co and Mn) for the juveniles in each of the four different streams. The strontium signal in the otolith of the juveniles was used as an indicator of freshwater origin and the time spent in the stream (size of juveniles). Adult marked pike in their migrating spawning phase were caught in each of the streams and otoliths were analysed. Defining earlier freshwater origin by the Sr signal from the otolith core to the increase in Sr when the fish as juvenile pike migrated to the sea, element composition was determined. A principal component analysis showed that the elemental fingerprint during the freshwater phase several years back was similar for adult fish and juveniles inhabiting the stream today. The results indicated native homing of the adults to a specific stream, a process further corroborated by results from electronic marking (Pit-tags) with the return of adult individuals over several consecutive years. We interpret the results as evidence that pike in the Baltic Sea consists of several sub-populations and are developed by homing to specific spawning streams. The results of the study may have implications for fishery management as pike in the Baltic Sea cannot be seen as homogenous “stock“, but instead consists of different, unique populations similar to the pattern demonstrated in salmon (Salmo salar).
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| 9. |
- Engstedt, Olof, et al.
(author)
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Elemental fingerprinting in otoliths reveals natal homing of anadromous Baltic Sea pike (Esox lucius L.)
- 2014
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In: Ecology of Freshwater Fish. - : Wiley. - 0906-6691 .- 1600-0633. ; 23:3, s. 313-321
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Journal article (peer-reviewed)abstract
- We examined the element pattern in the otoliths of a migratory fish species that inhabit the coastal areas in the brackish of the Baltic Sea. The northern pike (Esox lucius) show migratory behaviour, spawning in streams and rivers and foraging in the sea. We examined spawning migration in four nearby streams in the south-west part of the Baltic. Otolith analysis by microPIXE revealed unique elemental patterns (Sr, Zn, Br, Co and Mn) for the juveniles in each of the different streams. The strontium signal in the otolith of the juveniles was used as an indicator of freshwater origin and the time spent in the stream. Adult pike in their migrating spawning phase were caught in each of the streams. The elemental composition in otoliths in their freshwater phase (using juvenile pike in the streams as references) was determined. A principal component analysis showed that the elemental fingerprint during the freshwater phase several years back in time was similar for the adult fish and for juveniles inhabiting the stream today. The results indicated natal homing of the adults to a specific stream, a conclusion that was strengthened by the fact that marked fish returned to spawn over consecutive years. Anadromous pike in the Baltic Sea may thus be divided in subpopulations. The results of the study may have implications for fishery management, as pike in the Baltic Sea cannot be seen as homogenous population.
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| 10. |
- Malm, Torleif, et al.
(author)
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Bentiska processer på och runt artificiella strukturer i Sveriges kustvatten
- 2011
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Reports (other academic/artistic)abstract
- Inom de närmaste decennierna kommer sannolikt vindkraftsparker med en utbredning på många kvadratkilometer att byggas i svenska kustvatten. Dessa installationer kan påverka miljön med dess ekologiska samhällen på olika sätt; till exempel genom den redan kända reveffekten, genom att populationsstrukturen hos viktiga predatorer som fisk och mussel- och fiskätande fåglar kan förändras, eller genom förändrade strömmar som kan gynna vissa arter, främst mjukbottenarter, medan andra arter missgynnas. Därigenom kan trofiska kaskader (födovävsinteraktioner) ner i det bentiska samhället uppstå på såväl hård- som mjukbottnar. Hur parkerna påverkar de ekologiska samhällena beror troligen i hög grad på de initiala förhållandena i de aktuella områdena. Under perioden 2005–2009 utfördes en studie i syfte att undersöka den bentiska samhällsstrukturen på hårdbottnar före och efter byggnationen av större vindkraftparker. De områden som undersöktes var, Skottarevet i Kattegatt, Lillgrund i södra Öresund, Utgrunden II i södra Kalmarsund, Kårehamn utanför nordöstra Öland samt Klasådern utanför sydvästra Gotland. Av legala och ekonomiska orsaker byggdes endast en park, Lillgrund, under projekttiden. Vi fann betydande samhällsskillnader mellan områdena på såväl art- som funktionell nivå. Den största skillnaden fann vi mellan Kattegatt och Östersjön med stora skillnader i artsammansättningen och delvis med andra funktionella grupper. Även inom Östersjölokalerna hittades betydande skillnader. Samhällena i de båda sunden hade betydligt högre biomassor av musslor per kvadratmeter än de öppna områdena vid Gotland och Öland. Även algfloran skilde sig betydligt. I sunden dominerade övergödningsgynnade fintrådiga brunalger medan bottnarna längs de öppna kusterna i högre grad var beklädda med perenna rödalger. Vindkraftsutbyggnaden vid Lillgrund påverkade de bentiska samhällena måttligt men tydligt. Musslor och havstulpaner koloniserade fundament och erosionsskydd snabbt. Redan efter två år hade de artificiella och naturliga substraten en liknande samhällsstruktur. Dessutom verkar bottnarna som helhet ha påverkats av parken. Jämfört med tidigare år hade de naturliga substraten år 2009 en större biomassa av musslor och havstulpaner och en lägre biomassa av fintrådiga alger. Skillnaden var liten men signifikant.Slutsatsen av denna studie är att vindkraftsparker möjligen kan ge ekologiska effekter på bottensamhällena men att vår studie har sådana brister i geografisk och tidsmässig utsträckning att det inte säkert går att dra denna slutsats. Eftersom förhållandena runt våra kuster skiljer sig åt kan man inte dra säkra slutsatser från en plats. Det är också svårt att dra slutsatser från den korta period som förflutit sedan byggnationen av parken. Meteorologiska och oceanografiska processer som inte är relaterade till vindkraftsparken kan ha bidragit till resultatet.
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| 11. |
- Malm, Torleif, et al.
(author)
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Grazing effects of two freshwater snails on juvenile Fucus vesiculosus in the Baltic Sea
- 1999
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In: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 188, s. 63-71
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Journal article (peer-reviewed)abstract
- The low salinity in the non-tidal Baltic Sea excludes many species, including marine littorinoids. The only large gastropods that occur in substantial quantities in the central Baltic proper are the freshwater snails Lymnaea peregra (O.F. Müller) and Theodoxus fluviatilis (L.); both are known to consume filamentous green and brown algae. The main objective of the present study was to test the hypothesis that freshwater snails can exert substantial grazing pressure on juvenile and regenerating Fucus vesiculosus populations in the Baltic Sea. In laboratory experiments, both snail species were able to graze on F. vesiculosus germlings up to a size of approximately 0.8 to 1.0 mm. During the study period (autumn 1996 and spring and summer 1997), the largest F. vesiculosus germlings of the cohorts settled in September and May reached approximately 1.0 mm at the same time (July). Thus, to reach the 'safe' size and escape grazing requires about 8 mo for germlings settling in autumn but only 1 mo for germlings settling in spring. The survival and growth rate of new fronds from regenerating F. vesiculosus holdfasts in outdoor tank experiments were higher than for sexually recruited juveniles. After 1 yr, 95% of the holdfasts had survived, and the mean length (±SE) of the largest frond on each holdfast was 12 ± 2 mm. Grazing by L. peregra or T. fluviatilis did not affect regeneration or frond growth. During a long-term field study (1991 to 1994), an average of 8.5 ± 0.7 T. fluviatilis ind. dm-2 were found, with a maximum density of 40 ind. dm-2 in September. During a 1 yr study (1996), the average density of L. peregra was comparatively low and varied from 0.5 ind. dm-2 in April to 20 ind. dm-2 in August. The higher density found in August (L. peregra) and in September (T. fluviatilis) suggests that both species may have a grazing impact during this time. We conclude that both T. fluviatilis and L. peregra have the capacity to graze on zygotes and germlings of F. vesiculosus until they reach a safe size of approximately 0.8 to 1.0 mm. Both snail species can occasionally reach abundances high enough to affect the recruitment of F. vesiculosus. Freshwater snails do not affect the regeneration from holdfasts. However, because the time for germlings settled in autumn to reach a safe size is much longer than for germlings settled in spring, it is possible that even a low snail density has an impact on recruitment in the field. This will, however, require verification because levels of grazing activity during different times of the year are unknown.
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| 12. |
- Nilsson, Jonas, et al.
(author)
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Interaction between isopod grazing and wave action : a structuring force in macroalgal communities in the southern Baltic Sea
- 2004
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In: Aquatic Ecology. - 1386-2588 .- 1573-5125. ; 38:3, s. 403-413
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Journal article (peer-reviewed)abstract
- The macroalgal belt in the southern Baltic Sea may be partly structured by the interaction of physical and biological factors. A field study, spanning the 1990s, describes a rapid decline of the Fucus spp. stands along the wave-exposed Swedish southeast coast. During this period, a relative dominance of Fucus vesiculosus L. shifted to a relative dominance of Fucus serratus L. The decline of F. vesiculosus coincided with observations of large numbers of the grazing isopods Idotea baltica (Pallas) and Idotea granulosa Rathke, or with field observations of frequent grazing marks on Fucus fronds. I. baltica, but not I. granulosa, tended to aggregate in the declining Fucus spp. stands, indicating a strong preference for Fucus spp. In a mesocosm experiment I. baltica, when given a choice, grazed both Fucus species at weak water motion. At strong water motion grazing was concentrated on F. vesiculosus. It is hypothesized that one of the reasons I. baltica preferred F. vesiculosus to F. serratus at strong water motion may have been differences in habitat quality, like width of thallus, influencing the ability to cling to the plant. Smaller thallus, as in F. vesiculosus, thus is the preferred habitat for grazing of I. blatica. We postulate that the existence of F. serratus in the area may be favoured by strong wave action and moderate but not strong grazing by I. baltica, relaxing the interspecific competition from F. vesiculosus.
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| 13. |
- Nilsson, Jonas, et al.
(author)
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Long-term decline and recent recovery of Fucus populations along the rocky shores of southeast Sweden, Baltic Sea
- 2004
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In: Aquatic Ecology. - : Springer Science and Business Media LLC. - 1386-2588 .- 1573-5125. ; 38:4, s. 587-598
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Journal article (peer-reviewed)abstract
- The Fucus populations on rocky shores along 300 km of the coastal waters of southeast Sweden in the Baltic proper have been studied since 1984 at a number of fixed sites as part of monitoring programmes. This paper describes changes in distribution and abundance of F. vesiculosus and F. serratus during the period 1984–2001. Sheltered sites showed a consistent temporal and spatial pattern of Fucus spp. distribution over a coastline of 300 kilometres. The depth penetration and abundance of Fucus spp. increased during the 1980s. Around 1990 the development reversed as a consequence of grazing and in 1997 many sites were almost devoid of Fucus spp. Since 1998 both abundance and depth penetration have increased again, possibly as a result of local measures against eutrophication. Exposed sites, on the other hand, lost their Fucus populations at the beginning of the 1990s, and they have not recovered. Extended field studies lead us to deduce that the fixed sites referred to above were representative of the Fucus populations in the area investigated. Major declines, both at sheltered and exposed sites, are attributed to grazing by the isopod Idotea baltica. The populations of I. baltica may have been favoured by the continuing eutrophication of the Baltic, a series of mild winters in the 1990s, and a contemporary decline in some potential predators.
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| 14. |
- Nilsson, Jonas, et al.
(author)
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Marin inventering av makrovegetation öster om Listershuvuds naturreservat, runt Hanö och Malkvarn, hösten 2006
- 2007
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Reports (other academic/artistic)abstract
- På uppdrag av Länsstyrelsen i Blekinge genomfördes en marin inventering av makrovegetation i vattenområdet öster om Listershuvuds naturreservat inklusive Hanö och Malkvarn den 27-28:e september och den 16-17:e oktober 2006. Syftet med inventeringen var att få underlag för planering av ett eventuellt marint naturreservat. Undersökningen utfördes av Roland Engkvist, Olof Lövgren och JOnas Nilsson vid Högskolan i Kalmar, Institutionen för Biologi och Miljövetenskap.
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| 15. |
- Svensson, P. Andreas, et al.
(author)
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Distribution and host plant preference of Idotea baltica (Pallas) (Crustacea Isopoda) on shallow rocky shores in the central Baltic Sea
- 2004
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In: Sarsia. - : Informa UK Limited. - 0036-4827 .- 1503-1128. ; 89:1, s. 1-7
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Journal article (peer-reviewed)abstract
- Partially due to the mass occurrence of the isopod Idotea baltica, the perennial fucoid vegetation in the Baltic Sea has been destroyed over large areas and replaced by filamentous algae. With a combination of field investigations and laboratory experiments, we tested whether I. baltica preferred Fucus serratus to the dominant red alga Polysiphonia fucoides. In the field, the I. baltica density was higher inside F. serratus than P. fucoides patches when measured per unit area, but the situation was reversed if measured per biomass algae. Diet in the field was well correlated with the distribution of the isopods. A large proportion of the isopod faecal pellets collected in the field contained remnants of microalgae, planktonic animals, and bacteria, but the dominating material was always cells from the actual host plant. In a host plant preference experiment, I. baltica distributed evenly between the two host plant types, but the isopods grazed more heavily on F. serratus: We conclude that although F. serratus is the preferred food item in a choice situation, P. fucoides appears to have the potential to support the I. baltica population with food and shelter. A possible relationship between the weak host plant preference and the low stocks of predatory fish is discussed.
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| 16. |
- Worm, Boris, et al.
(author)
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Marine diversity shift linked to interactions among grazers, nutrients and propagule banks
- 1999
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In: Marine Ecology Progress Series. - 0171-8630. ; 185, s. 309-314
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Journal article (peer-reviewed)abstract
- Diverse coastal seaweed communities dominated by perennial fucoids become replaced by species-poor turfs of annual algae throughout the Baltic Sea. A large scale field survey and factorial field experiments indicated that grazers maintain the fucoid cornmunity through selective consumption of annual algae. Interactive effects between grazers and dormant propagules of annual algae. stored in a 'marine seed bank', determine the response of this system to anthropogenic nutrient loading. Nutrients override grazer control and accelerate the loss of algal diversity in the presence but not in the absence of a propagule bank. This irnplies a novel role of propagule banks for community regulation and ecosystem response to manne eutrophication.
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