Biological impact of eutrophication in the bay of somme and the induction and impact of anoxia

Desprez, Michel; Rybarczyk, Hervé; Wilson, James G.; Ducrotoy, J.-P.; Sueur, F.; Olivesi, R.; Elkaïm, B.

doi:10.1016/0077-7579(92)90054-i

Cited by 51 publications

(30 citation statements)

References 13 publications

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“…During benthic surveys in the 1980s, this increase also became obvious in Niedersachsen (Michaelis et al, unpubl. ) Since the early 1970s, "green tides" of macroalgae, principally Ulva and Enteromorpha, have been reported from various sites of the European coasts: from the Swedish side of the Kattegat (Rosenberg, 1992), the Island of Funen in Denmark (Funen County Council, 1991), different places around the British Isles (Perkins & Abbott, 1972;Joint, 1978;Lowthion et al, 1985), the French coast of the Channel (Desprez et al, 1992;Piriou & M4nesguen, 1992) and the Adriatic Sea .…”

Section: Discussionmentioning

confidence: 99%

Macroalgal mass development in the Wadden Sea: First experiences with a monitoring system

Kolbe

Kaminski

Michaelis

et al. 1995

Helgolander Meeresunters

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The distribution and cover density of macroalgae (Chlorophyta, Ulvaceae) were estimated by means of aerial surveys in 1990-1992 in the Wadden Sea of Niedersachsen, an intertidal area of some 1200 km 2 situated at the German North Sea coast. Each year, up to a maximum of 15 % of the total area was covered by algae. The spatial distribution was heterogeneous. In some subregions the macroalgal carpets covered from 30 % up to 60 % of the tidal flats.The cover density was at its peak in 1990. Additionally, tentative ground truth investigations were carried out on species composition. Reviewing other reports of macroalgal mass development at various sites in Europe, it is assumed that in the German Wadden Sea the recent macroalgal blooms have to be regarded as a response to eutrophication, and will presumably remain a chronic problem for many years to come.

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Section: Discussionmentioning

confidence: 99%

Macroalgal mass development in the Wadden Sea: First experiences with a monitoring system

Kolbe

Kaminski

Michaelis

et al. 1995

Helgolander Meeresunters

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“…Macrobenthic surveys throughout the 1980s and 1990s have recorded periodic mass mortalities attributed to anoxia promoted by h g h summer temperatures and organic enrichment (Rybarczyk et al 1996). Although P. elegans proliferated during periods of disturbance, population densities fluctuated widely (Desprez et al 1992); maximum recorded density in Sornme Bay is 600000 ind. m-' (Morgan 1997).…”

Section: Methodsmentioning

confidence: 99%

Evidence for poecilogony in Pygospio elegans (Polychaeta:Spionidae)

Morgan¹,

Rogers²,

Paterson³

et al. 1999

Mar. Ecol. Prog. Ser.

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The spionid polychaete Pygospio elegans displays more than one developmental mode. Larvae may develop directly, ingesting nurse eggs while brooded in capsules within the parental tube. or they may hatch early to feed in the plankton before settling. Asexual reproduction by architomic fragmentation also occurs. Geographically separated populations of P. elegans often display different life histories. Such a variable life history within a single species may be interpreted either as evidence of sibling speciation or of reproductive flexibility (poecilogony). Four populations from the English Channel were found to demonstrate differing life histories and were examined for morphological and genetic variability to determine whether P, elegans is in fact a cryptic species complex. Significant but minor inter-population polymorphisms were found in the distribution of branchiae and the extent of spoonlike hooded hooks. These externally polymorphic characters did not vary with relation to life history, and variation fell within the reported range for this species. Cellulose acetate electrophoresis was used to examine 10 allozyrne loci, 5 of which were polymorphic. Overall, observed heterozygosity (H, = 0.161) was lower than that expected under Hardy-Weinberg equilibrium (H,= 0.228). Significant heterozygote deficiencies, detected at the Est' and Xdh' loci in all populations (except Xdh' at Ryde Sand, Isle of Wight, UK), are discussed. F-statistics were used to examine patterns of genetic structuring anlong both separate and pooled populations. Fn values at all polymorphic loci indicated a significant level of genetic differentiation between populations, most probably related to isolation by geographic distance. No direct relationship between life history and genetic structure could be detected. Overall genetic identity among the 4 populations was high (I = 0.977 to 0.992). Overall, populations displaying larval brooding did not appear to be reproductively isolated from populations displaying a fully planktonic larval mode. Present data support the hypothesis that P. elegans is poecilogonous.

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“…m -2 . (3) Cockles could be weakened by some physiological stress induced by anoxia or oxygen deficiency (Brafield 1963, Rosenberg & Loo 1988, Modig & Olafsson 1998, especially under persistent macroalgal mats (Desprez et al 1992, de Montaudouin 1995. None of these factors could have affected cockles for 13 mo in this area.…”

Section: Emergence and Disappearance Of Surface Cocklesmentioning

confidence: 99%

“…Its population abundance and biomass fluctuate greatly in space and time (Ducrotoy et al 1991) but the causes of this variability are not yet completely understood (Jensen 1992). Mortality of adult cockles has often been ascribed to predation by epifauna (Sanchez-Salazar et al 1987a,b) or coastal birds (Hancock & Urquhart 1965, Seed & Brown 1975, sedimentary movements (Deltreil & His 1970, Dewarumez 1983, Desprez et al 1987, de Montaudouin 1995 or dystrophic crisis (Rosenberg & Loo 1988, Desprez et al 1992. Although frequent in intertidal bivalves, parasitism has rarely been identified as a source of mortality in cockles (Deltreil & His 1970, Jonsson & André 1992.…”

Section: Introductionmentioning

confidence: 99%

Cockle emergence at the sediment surface: 'favourization' mechanism by digenean parasites?

Desclaux

Montaudouin²,

Bachelet³

2002

Dis. Aquat. Org.

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The aim of the present work was to assess the effect of digenean trematodes on indirect mortality of the cockle Cerastoderma edule, an infaunal bivalve. The tested hypothesis was that parasites altered the burrowing capacity of cockles and thus exposed them at the sediment surface, where they are more vulnerable to predators. If the predator is the final host, this mechanism, which drives the cockle out of the sediment, is considered as a 'favourization'. Cockle populations from 2 stations in Arcachon Bay (France) -Banc d'Arguin (oceanic situation) and La Canelette (lagoonal situation) -were sampled for 1 yr. At La Canelette, monitoring every 2 d showed that 50% of adult cockles regularly migrated to the sediment surface at a rate of 5 cockles m -2 yr -1 and disappeared in a few days. In the laboratory, 67% of these 'surface cockles' did not burrow again, suggesting that they would die in the field. Moreover, mortality measured after 7 d in the laboratory was 2 to 5 times higher than mortality of 'buried cockles', at both stations and particularly during summer. Species richness and abundance of digeneans from both stations were compared in 'buried' and 'surface' individuals to determine whether parasites played a role in cockle migration and mortality. Ten and 9 digeneans were found at Banc d'Arguin and La Canelette, respectively, with Himasthla quissetensis and Labratrema minimus being the most prevalent and abundant species at both stations. The abundance of H. quissetensis was slightly higher in surface cockles at Banc d'Arguin, but the difference fluctuated with station and cockle age (or size). L. minimus prevalence was only higher in surface cockles at La Canelette. In the latter station, we estimated that L. minimus and H. quissetensis were responsible for the emergence of 9 and 2%, respectively, of the buried cockles. Although this favourization mechanism may induce some mortality in cockles, it does not alone explain the magnitude of the observed mortalities (41 and 57% at La Canelette and Banc d'Arguin, respectively). A correspondence analysis did not show the presence of a particular parasite community in buried or surface cockles, which could explain these high surface cockle mortalities in association with the 2 dominant digeneans.

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Biological impact of eutrophication in the bay of somme and the induction and impact of anoxia

Cited by 51 publications

References 13 publications

Macroalgal mass development in the Wadden Sea: First experiences with a monitoring system

Macroalgal mass development in the Wadden Sea: First experiences with a monitoring system

Evidence for poecilogony in Pygospio elegans (Polychaeta:Spionidae)

Cockle emergence at the sediment surface: 'favourization' mechanism by digenean parasites?

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