Search results for "Benthic zone"
showing 10 items of 265 documents
Horizontal and vertical food web structure drives trace element trophic transfer in Terra Nova Bay, Antarctica
2019
Abstract Despite a vast amount of literature has focused on trace element (TE) contamination in Antarctica during the last decades, the assessment of the main pathways driving TE transfer to the biota is still an overlooked issue. This limits the ability to predict how variations in sea-ice dynamics and productivity due to climate change will affect TE allocation in the food web. Here, food web structure of Tethys Bay (Terra Nova Bay, Ross Sea, Antarctica) was first characterised by analysing carbon and nitrogen stable isotopes (δ13C, δ15N) in organic matter sources (sediment and planktonic, benthic and sympagic primary producers) and consumers (zooplankton, benthic invertebrates, fish and …
Effect of different substrata on rhizome growth, leaf biometry and shoot density of Posidonia oceanica
2013
The effects of different substratum typologies on Posidonia oceanica growth and morphology were estimated in four Sicilian meadows using Generalized and Linear Mixed Models combined with retrodating and biometric analyses. Substratum exerted a multiple effect, resulting in different biometric features for P. oceanica shoots settled on rock from those growing on sand and matte. On rock, values for growth rate, leaf length and shoot surface were lower than those on other substrata, with 42%, 23% and 32% the highest degree of difference respectively. The present study may have interesting methodological consequences for the comprehensive understanding of the causative variables potentially aff…
Tracking multiple pathways of waste from a northern bluefin tuna farm in a marine-coastal area.
2011
Aquaculture of bluefin tuna in Mediterranean coastal waters has generated growing concern about the negative environmental effects. In the present isotopic study we examined the dispersal and fate of organic matter derived from a Mediterranean tuna farm in the surrounding environment. An overall enrichment in the heavy nitrogen isotope was found in the feed and in farmed tunas, indicating the input of isotopically traceable organic matter in the system. Waste was clearly traceable in the water column up to 1000 m from the cages, while only slight accumulation occurred in the sediment just below the cages. Waste was isotopically shown also to contribute to the diet of demersal and benthopela…
Initial Fish-Farm Impact on Meiofaunal Assemblages in Coastal Sediments of the Western Mediterranean
1999
We 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 …
Contribution of planktonic and benthic food sources to the diet of the reef-forming vermetid gastropod Dendropoma petraeum in the western Mediterrane…
2012
Abstract In the Mediterranean Sea, the vermetid Dendropoma petraeum (Monterosato, 1884) forms highly biodiverse reefs that have received increasing attention in recent years although very little is known about the food habit of this species. The main goal of this study was to describe the trophic role of planktonic and benthic food sources for D. petraeum . Specimens from three morphological zones of the reef (inner edge, cuvette and outer edge) at two sites with different wave exposure along the north-western coast of Sicily (Italy; western Mediterranean) were compared for δ 13 C and δ 15 N. Isotopic determinations were also carried out on potential food sources identified in epilithon, re…
Sedimentary and particulate organic matter: mixed sources for cockleCerastoderma glaucumin a shallow pond, Western Mediterranean
2007
Seasonal changes in feeding habits and diet of the cockle Cerastoderma glaucum (Mollusca, Bivalvia) were analysed using carbon (δ 13 C) and nitrogen (δ 15 N) stable isotopes. I aimed to investigate the role of benthic and pelagic sources in the diet of this dominant infaunal bivalve on a western Mediterranean sandy bottomed pond. Adult C. glaucum and all potential organic sources (particulate and sedimentary organic matter, seagrass, macroalgae, het- erotrophic detritus) were collected and analysed for δ 13 Ca ndδ 15 N. In total 5 dominant organic sources were found, ranging between -21.0 and -8.0%� for δ 13 C and from 3.0 to about 7.0%� for δ 15 N. C. glaucum assimilated fraction ranged be…
Caulerpa racemosa var. cylindracea as a potential source of organic matter for benthic consumers: evidences from a stable isotope analysis.
2008
Caulerpa racemosa var. cylindracea has been invading various types of substrates in wide areas throughout the Mediterranean Sea. However, the effects of the distribution of this alga on zoobenthos are scanty. The aim of this study was to evaluate the effects of C. racemosa invasion on the feeding habits of some zoobenthic taxa inhabiting the upper infralittoral rocky shores. This was done by identifying the isotopic N and C ratios of several potential food sources and testing differences in isotope composition among the taxa collected from areas invaded and not-invaded areas by C. racemosa. Results suggest that C. racemosa detritus was a significant food source for the polychaete Syllis pro…
Aquaculture impact on benthic microbes and organic matter cycling in coastal Mediterranean sediments: a synthesis
2003
Microbial assemblages and organic matter composition as well as their response to the disturbance induced by mussel and fish-farm biodeposition were compared in several areas of the Mediterranean: La Spezia (Ligurian Sea), Gaeta (Tyrrhenian Sea), Cattolica (Adriatic Sea) and Cyprus (Levantine Sea), on both unvegetated and Posidonia bed sediments. In all systems investigated, organic matter (as biopolymeric carbon) accumulated in aquaculture impacted sediments. Among the main biochemical classes, lipids appeared to be a good tracer of aquaculture impact, especially in fish-farm sediments. Exoenzymatic activities displayed higher values in sediment beneath the cages, indicating faster organic…
Analysis of stable carbon and nitrogen isotopes as a tool for assessing the environmental impact of aquaculture: a case study from the western Medite…
2005
Stable carbon and nitrogen isotope ratios ( 13C/ 12 C and 15N/14 N) of in situ dominant primary producers and consumers were investigated to assess the impact on a natural ecosystem of a land-based fish farm along the south-western coast of Sicily (Italy). The putatively impacted area close to the farm along outfall was compared with other locations at increasing distances from the outfall. Carbon and mainly nitrogen stable isotopes revealed evidence of widespread aquaculture waste in the study site: benthic organisms collected in the impacted area showed more enriched δ 15N signatures than those at greater distances from the outfall, suggesting a large contribution of aquaculture waste to …
Heterotrophic bacteria community and pollution indicators of mussel--farm impact in the Gulf of Gaeta (Tyrrhenian Sea).
2001
Field studies were carried out to determine and compare the impact of organic loads due to the biodeposition of a mussel farm on the water quality and sediment in a coastal area of the Tyrrhenian Sea (Western Mediterranean). A total of five environmental and five microbial parameters were examined from March, 1997 to February, 1998 on a monthly basis at three stations: the first was located under the mussel farm, the second located at about 40 m away from the mussel farm, while the third designed as a control was at about 1-km. No clear changes in the physical characteristics of the water masses were observed, comparing the three sampling sites and the water column generally showed homogene…