1,721,095 research outputs found
Meiofaunal colonisation on artificial substrates: a tool for biomonitoring the environmental quality on coastal marine systems.
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Initial fish-farm impact on meiofaunal assemblages in coastal sediments of the Western Mediterranean
No full textWe studied the initial impact of organic loads due to the biodeposition of a new fish farm in a non-impacted coastal area of the Tyrrhenian Sea (Western Mediterranean). Sediment chemistry and meiofaunal assemblages were investigated from July 1997 to February 1998 on a monthly basis at two stations: the first was located under the fish farm, while the second was at about 1 km distance, and served as control. Variations in the biochemical composition of the sedimentary organic matter and meiofaunal community structure were also related to changes in reared fish biomass. The presence of the cage-induced rapid changes in the benthic compartment: the sediments reached rapidly (i.e., after only 6 weeks) reducing conditions. A significant accumulation of biopolymeric carbon was observed beneath the cage both at the beginning of this study and 5-7 months after cage disposal and appeared to be related to the fish-farm production cycle. Sedimentary proteins and lipids resulted to be good descriptors of medium-term fish-farm impact. Changes in the sediment conditions beneath the cage determined a significant reduction of the total meiofaunal density (on average for 70%). Most meiofaunal taxa, including nematodes, copepods and ostracods displayed a significant decrease in the farm sediments within 3 months after cage installation. Kinorhynchs appeared extremely sensitive to reducing conditions of the sediments and disappeared almost completely, whereas polychaete densities remained unvaried. After initial impact meiofaunal assemblages responded to organic enrichment recovering, at least partially, their apparent structural characteristics. These data indicate that studies carried out several months after cage deployment might underestimate the actual impact on benthic assemblages. Copyright (C) 1999 Elsevier Science Ltd
Meiofaunal production and energy transfer efficiency in a seagrass Posidonia oceanica bed in the western Mediterranean
No full textInitial Fish-Farm Impact on Meiofaunal Assemblages in Coastal Sediments of the Western Mediterranean
No full textCase studies using nematode assemblage analysis in aquatic habitats
No full textDanovaro R, Gambi C, Höss S, Mirto S, Traunspurger W, Zullini A. Case studies using nematode assemblage analysis in aquatic habitats. In: Wilson M, Khakouli-Duarte T, eds. Nematodes as environmental bioindicators. Wallingford: CABI; 2009: 146-171
Comparison of growth performance and biometric relationships in two reciprocal sturgeon hybrids reared in net cages (Sicily, Mediterranean)
No full textThis study was designed to investigate growth performance in two sturgeon hybrids reared in two quadrangular £oating cages moored in an arti¢cial pond, representing the ¢rst experience of sturgeon culture performed at Southern Mediterranean latitudes. The research was carried out from December 2000 to July 2001 and tested the growth performance, feeding parameters and biometric relationships. The sturgeons were randomly collected from the cages on a monthly basis, and total length, standard
length (SL) and wet weight (WW) were recorded. The speci¢c daily growth rate (SGRW) as somatic WW, food conversion ratio and condition factor (CF) were calculated. Biometric relationships, as linear regression, were also calculated on SL andWWdata. Both hybrids grew slowly from December toApril, but faster during the warm months. The growth performance of the two hybrids seems to be in£uenced by variability of the environmental conditions and, for both ¢sh groups, there was a strong correlation between water temperature and SGRW at temperatures below 25 1C. The CF (constantly below 1) was similar for both hybrids. The regression analysis for WW and SL calculated for the entire period showed a positive allometry for both hybrids, indicating that the ¢shes grew in weight at a greater rate than required to maintain constant body proportion
Benthic microbial indicators of fish farm impact in a coastal area of the Tyrrhenian Sea
No full textWe studied the impact of organic loads due to the biodeposition of a fish farm in a nonimpacted coastal area of the Tyrrhenian Sea (Western Mediterranean). Sediment chemistry and benthic microbial community were investigated from July 1997 to February 1998 on monthly basis at two stations: one was located under the fish farm, while the second was about 1 km away, and served as a reference site. The presence of the cage induced rapid changes in the benthic conditions: the sediments were rapidly (after 6 weeks) reduced. A significant accumulation of
biopolymeric carbon was observed beneath the cage both 2 weeks after the initial cage deployment, on non-impacted sediments, and 5–7 months after, and appeared to be related to the fish farm production cycle. The density of microbial communities beneath the fish farm increased only during the first month of farming activity (July) and partially 7 months after cage disposal (i.e. in January), when there was a significant sediment organic enrichment. Additional evidence of
rapid impact of the fish farm on the benthic bacterial communities is provided by the increase in the numbers of autofluorescent microbial cells. The photosynthetic eukaryotic cells displayed a highly reduced contribution to total autofluorescent microbial density, indicating that their decrease is related with biopolymeric carbon accumulation, and probably was due also to ‘‘shadow effect’’
induced by suspended material, coming from the fish farm, on the environment below. We propose here, to apply the ratio of culturable heterotrophic bacteria to microbial direct counts (CFU/MDC) to detect fish farm impact. In cage sediments, organic enrichment and the consequent modification of the characteristics of the benthic environment, determined an increase in aerobic heterotrophicbacteria and vibrio density indicating that they are efficient colonizers of organic-rich sediments.
Densities of Escherichia coli and Enterococci were not significantly higher than in the reference site, and are likely of terrestrial origin. Thus they cannot be used as specific indicators of fish farm impact
Meiofaunal assemblages associated with scallop beds (Adamussium colbecki) in the coastal sediments of Terra Nova Bay (Ross Sea, Antarctica).
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