| 1. |
- Baden, Susanne P., 1952, et al.
(author)
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Between-individual variation in haemocyanin concentrations in the Norway lobster Nephrops norvegicus following exposure to hypoxia and manganese
- 2003
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In: Marine Biology. - 0025-3162. ; 143:2, s. 267-273
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Journal article (peer-reviewed)abstract
- Environmental hypoxia and the release of reduced manganese (Mn) are often combined stress factors in marine sediments. Previous investigations have shown that hypoxia induces variable responses in the concentration of the respiratory pigment haemocyanin (Hc) of crustaceans. A recent study demonstrated that the magnitude and direction of the changes was dependent on the initial level of Hc in individuals of the Norway lobster Nephrops norvegicus. The changes also took place within 24 h rather than days as suggested by previous studies. In this present study we investigated changes of Hc in individual N. norvegicus in uncontaminated sea water after exposure to and release from realistic hypoxic stress (PO2 = 6.0 kPa). Furthermore we investigated how concomitant exposure to realistic concentrations of manganese (20 mg 1(-1)) modified the responses we observed. We confirmed a between-individual variation in response and a change in Hc towards an optimum level after hypoxia, but also showed that changes that took place post-hypoxic exposure occurred over a timescale similar to that of the hypoxic response itself. Manganese exposure resulted in no significant changes in Hc whereas Mn exposure combined with hypoxia resulted in a significant decrease (15%) in all individuals independent of initial Hc. N. norvegicus was thus unable to compensate for the effects of hypoxia by synthesis of Hc after exposure to naturally occurring Mn concentrations.
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| 2. |
- Baden, Susanne P., 1952, et al.
(author)
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Manganese accumulation by the antennule of the Norway lobster Nephrops norvegicus (L.) as a biomarker of hypoxic events.
- 2003
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In: Marine Environmental Research. - 0141-1136. ; 55:1, s. 59-71
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Journal article (peer-reviewed)abstract
- In laboratory tests, manganese accumulation by the appendages of the sediment burrowing Norway lobster, Nephrops norvegicus (L.) (including the lateral antennules) was approximately three times greater [600 mug Mn g(-1) (dry weight) after 5 days in 20 mg Mn l(-1)] than that by the carapace. The accumulation was linearly dose-dependent (10-40 mg Mn l(-1)) and duration-dependent (2-30 days), and showed no decrease after 3 weeks in undosed seawater. A high manganese uptake to the lateral antennules during hypoxia in the field was verified from the SE Kattegat, Sweden. These results indicate that accumulation of Mn on the mobile appendages of the Norway lobster fulfils most of the criteria for a biomarker of exposure to hypoxia. Using these measurements in conjunction with Mn concentrations in the internal tissues, it may be possible to resolve both the timing and the extent of the Mn exposure and the underlying hypoxic event. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Baden, Susanne P., 1952, et al.
(author)
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Vanishing seagrass (Zostera marina, L.) in Swedish coastal waters
- 2003
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In: Ambio. - 0044-7447. ; 32:5, s. 374-377
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Journal article (peer-reviewed)abstract
- Along the Swedish Skagerrak coast eelgrass (Zostera marina) is a dominant phanerogam on shallow soft bottoms. Eelgrass meadows are important biotopes for many crustacean and fish species being either migratory or stationary. During the 1980s, inventories of the shallow coastal areas with eelgrass have been carried out along the Swedish west coast as a basis for coastal zone management. In the present study we revisited 2000 ha of eelgrass meadows in 5 coastal regions along 200 km of the Skagerrak coast. The inventory was made with the same methods (aquascope) as during the 1980s, but increasing the mapping accuracy by using a Global Positioning System (GPS). The results from this study show that the areal extension of Zostera marina has decreased 58% in 10-15 years with great regional variations. The decline was mainly restricted to the shallow parts of the meadow. The causes and ecological consequences are discussed.
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| 4. |
- Hernroth, Bodil, 1951, et al.
(author)
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Manganese induced immune suppression of the lobster, Nephrops norvegicus
- 2004
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 70:3, s. 223-231
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Journal article (peer-reviewed)abstract
- Manganese (Mn) is one of the most abundant elements on earth, particularly in the soft bottom sediments of the oceans. As a micronutrient Mn is essential in the metabolic processes of organisms. However, at high concentrations the metal becomes a neurotoxin with well-documented effects. As a consequence of euthrophication, manganese is released from bottom sediments of coastal areas and the Norway lobsters, Nephrops norvegicus, can experience high levels of bioavailable Mn2+. Here, we present the first report showing that Mn also affects several fundamental processes in the mobilisation and activation of immunoactive haemocytes. When N. norvegicus was exposed to a realistic [Mn2+] of 20 mg l(-1) for 10 days 24.1 mug ml(-1) was recorded in the haemolymph. At this concentration the total haemocyte count was reduced by ca. 60%. By using BrdU as a tracer for cell division, it was shown that the proliferation rate in the haematopoietic tissue did not increase, despite the haemocytepenia. A gene coding for a Runt-domain protein, known to be involved in maturation of immune active haemocytes in a variety of organisms, was identified also in haemocytes of N. norvegicus. The expression of this gene was >40% lower in the Mn-exposed lobsters as judged by using a c DNA probe and the in situ hybridisation technique. In response to non-self molecules, like lipopolysaccharide, (LPS), the granular haemocytes of arthropods are known to degranulate and thereby release and activate the prophenoloxidase, system, necessary for their immune defence. A degranulation assay, tested on isolated granular haemocytes, showed about 75% lower activity in the Mn-exposed lobsters than that for the unexposed. Furthermore, using an enzymatic assay, the activation per se of prophenoloxidase by LPS was found blocked in the Mn-exposed lobsters. Taken together, these results show that Mn exposure suppressiA fundamental immune mechanisms of Norway lobsters. This identifies a potential harm that also exists for other organisms and should be considered when increasing the distribution of bioavailable Mn, as has been done through recently introduced applications of the metal.
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| 5. |
- Krång, Anna Sara, 1972, et al.
(author)
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The ability of the amphipod Corophium volutator (Pallas) to follow chemical signals from con-specifics
- 2004
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In: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 310:2, s. 195-206
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Journal article (peer-reviewed)abstract
- The amphipod Corophium volutator (Pallas) is a tube-dwelling species that only occasionally leaves its burrow. Animals that do crawl on the sediment are mainly males, apparently in search of females. This study was designed to determine whether C volutator males and females release chemical signals that attract con-specifics, and if so, whether these signals are gender specific. Laboratory experiments were conducted on the over-wintering generation during their reproductive season, using a Y-maze choice test apparatus. The results show that C volutator females release chemical signals that attract males. In the field, the attractant may guide males in search of burrowed females. In addition, male odour tends to attract males, while females do not follow chemical signals from con-specifics. We thereby show, on gender-specific chemical attraction of this species. (C) 2004 Elsevier B.V. All rights reserved.
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