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- Berg, S., et al.
(author)
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Analysis of airborne organic lead
- 1984
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In: Biological effects of organolead compounds. - Boca Raton, FL : CRC Press. - 0849353092 ; , s. 278-
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Book chapter (other academic/artistic)
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2. |
- Berglund, Anders, et al.
(author)
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Biotic and abiotic factors determining the distribution of two prawn species: Palaemon adspersus and P. squilla
- 1981
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In: Oecologia. - 0029-8549 .- 1432-1939. ; 49:3, s. 300-304
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Journal article (peer-reviewed)abstract
- The reasons behind the absence of the prawn Palaemon adspersus and the presence of P. squilla in rockpools and on bare sand bottoms were studied. Some maximal abundances in different habitats are given. Introduction experiments into natural and artificial rockpools and measurements of tolerance towards low oxygen levels showed that nocturnal hypoxia excluded P. adspersus which was significantly more sensitive to oxygen depletion. Respiration rates measured by the closed-bottle method showed no interspecific difference. On bare sand bottoms P. aspersus was probably excluded by predators, since predator exclusion experiments in cages and predator inclusion experiments in containers showed that P. adaspersus was more vulnerable to predation than P. squilla.The costs for being able to cope with a wide array of habitat in P. squilla are probably balanced by the benefits of access to habitats such as intertidal rockpools, very shallow bottoms and deeper sand bottoms. Tolerance towards abiotic factors extends its habitat range upwards into shallower waters, and tolerance towards biotic factors, i.e. predation, extends it downwards.
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3. |
- Berglund, Anders
(author)
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Coexistence, size overlap and population regulation in tidal vs non-tidal Palaemon prawns
- 1982
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In: Oecologia. - 0029-8549 .- 1432-1939. ; 54:1, s. 1-7
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Journal article (peer-reviewed)abstract
- The effect of increased habitat heterogeneity in tidal areas on coexistence between Palaemon prawns was studied at eight sites along the European Atlantic coast. Two species which are sympatric in non-tidal areas, Palaemon adspersus Rathke and P. squilla (L.) are largely allopatric in tidal areas, and the sympatric size difference decreases in allopatry. In tidal areas the smaller species, P. squilla, is restricted to brown algal belts and rockpools. A third species, P. serratus (Pennant), larger than the others, occurs under oceanic salinities in subtidal brown algal belts and there has forced P. squilla to restrict its habitat distribution to adjacent intertidal rockpools. At estuarine salinities, however, P. squilla also inhabits the brown algal belts. A larger diel variation in stomach fullness index in P. squilla than in P. adspersus persists in non-tidal areas. Abiotic factors probably restrict the two largest species, viz. P. adspersus and P. serratus, to subtidal environments; these species are sensitive to the extremes in salinity, temperature or O2 levels characteristic of the intertidal zone. Competition and/or predation probably relegates P. squilla to the intertidal zone. In non-tidal areas, where this zone is reduced, P. squilla increases its niche width and coexists with P. adspersus, and the size differentiation associated with sympatry may reduce interspecific competition.
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4. |
- Berglund, Anders, et al.
(author)
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Genetic differentiation in populations of two Palaemon prawn species at the Atlantic east coast : does gene flow prevent local adaptation?
- 1983
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In: Marine Biology. - 0025-3162 .- 1432-1793. ; 77:1, s. 49-57
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Journal article (peer-reviewed)abstract
- Two Palaemon prawn species, P. adspersus Rathke and P. squilla (L.), occur along the European Atlantic coast. In areas heavily affected by tides (Netherlands and France), one species, P. squilla, inhabits the intertidal zone, and P. adspersus is found subtidally in the Zostera marina meadows. In areas with small tidal ranges (Sweden) both species occur in the Z. marina zone, and here the body size of P. squilla is reduced, something that in turn reduces reproductive output in this species. Is adaptive improvement in non-tidal P. squilla populations prevented by too extensive gene flow from tidal areas? To wanswer this, genetic differentiation was studied by horizontal starch gel electrophoresis. Each of the two species was sampled at five sites along the European Atlantic coast. Twenty-two enzymes representing 25 loci were scored. Significant genetic heterogeneity between sites was found in both species. Thus the extensive gene flow hypothesis was not supported by the results, and non-tidal populations ought to have the possibility to adapt to local conditions.
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