Search results for "Fish"

Year-round variation in the isotopic niche of Scopoli's shearwater (Calonectris diomedea) breeding in contrasting sea regions of the Mediterranean Sea

2022

Top marine predators are key components of marine food webs. Among them, long-distance migratory seabirds, which travel across different marine ecosystems over the year, may experience important year-round changes in terms of oceanographic conditions and availability of trophic resources. We tested whether this was the case in the Scopoli’s shearwater (Calonectris diomedea), a trans-equatorial migrant and top predator, by sampling birds breeding in three environmentally different regions of the Mediterranean Sea. The analysis of positional data and stable isotopes (δ13 C and δ15N) of target feathers revealed that birds from the three regions were spatially segregated during the breeding per…

Polyculture as a tool to increase the economic income: a study case in the Gulf of Castellammare

2010

Polyculture is a practice involving integration between organisms of different trophic levels (i.e. fish with low-trophic-level organism like molluscs and/or algae). This paper, reporting on a field experiment carried out during 2004 in the Gulf of Castellammare (South Tyrrhenian), showed that mussels transplanted in areas under fish farm influence grew up better than mussels transplanted far from fish farm. Thus, results pointed out polyculture as a reliable tool for i) increasing local bivalve production, ii) obtaining the reduction of importation from other countries and iii) increasing the environmental sustainability of fish aquaculture.

Food web reconstruction gives evidence of increased trophic levels in no-trawl areas: the red mullet, Mullus barbatus L. case in northern Sicily

2018

This study was aimed at identifying the food web of the red mullet, Mullus barbatus in order to understand how it is affected by trawling disturbance. To achieve this objective: a) the main features of the red mullet habitat were investigated; b) the food web of this habitat was studied in two no-trawl areas and in two areas open to trawling. The working hypothesis is that trawling affects the biochemistry of the sediment and the trophic structure of the benthic assemblage. It was predicted: a) less biomass, smaller size and higher production rate in the benthic assemblages of protected gulfs; b) higher average trophic level for both the red mullet and its predators in protected gulfs; c) a…

Fish-seastar facilitation leads to algal forest restoration on protected rocky reefs

2015

AbstractAlthough protected areas can lead to recovery of overharvested species, it is much less clear whether the return of certain predator species or a diversity of predator species can lead to re-establishment of important top-down forces that regulate whole ecosystems. Here we report that the algal recovery in a Mediterranean Marine Protected Area did not derive from the increase in the traditional strong predators, but rather from the establishment of a previously unknown interaction between the thermophilic fish Thalassoma pavo and the seastar Marthasterias glacialis. The interaction resulted in elevated predation rates on sea urchins responsible for algal overgrazing. Manipulative ex…

Effects of Ocean Acidification on physiology, behaviour and ecology of fish

CO2 concentration in the atmosphere is increasing at unprecedented rate since the last 800,000 years due to rising fossil fuel combustion, industrial processes and land use by humans. By absorbing part of this gas from the atmosphere, Oceans contribute to the mitigation of climatic changes, but at the cost of greater modifications of their physical and chemical characteristics. CO2 dissolved in the seawater leads to increased bicarbonate (HCO3 -) and hydrogen ions (H+) concentrations with a consequent pH drop, a phenomenon known as Ocean Acidification (OA). If global policy will not put in force mitigation measures to reduce CO2 emissions, it is projected that partial pressure of dissolved …

Growth and reproductive simulation of candidate shellfish species at fish cages in the Southern Mediterranean: Dynamic Energy Budget (DEB) modelling …

2012

Abstract A Dynamic Energy Budget (DEB) model is used to simulate growth and reproduction of the shellfish Mytilus galloprovincialis and Crassostrea gigas in an integrated multi-trophic aquaculture (IMTA) farm scenario situated in the Southern Mediterranean (the Gulf of Castellammare, Sicily). We modelled the effect of primary production enrichment at fish cages on shellfish growth and life history traits using 4 years-hourly temperature data (01 January 2006–31 December 2009) at a depth of 1 m. Outputs of the DEB simulations were: the maximum theoretical total shell length of shellfish, the potential reproductive outputs and the mean annual von Bertalanffy growth rate. There was a mean incr…

Neglected fishery data sources as indicators of pre‐industrial ecological properties of Mediterranean swordfish ( Xiphias gladius , Xiphiidae)

2022

Management of fish populations and ecosystems suffers from data and knowledge gaps, particularly with respect to how humans and nature affect dynamics at multi-decadal and longer time scales. However, collection of new data which indicates population or ecosystem status is slow and expensive. Here we analyse c. 110 years of neglected fishery data for an overexploited top predator, swordfish, in the Mediterranean Sea. These data are available at scales of high time–space–biological resolution (i.e., sub-weekly, sub-regional sea; individual weights) and allow different ecological questions to be addressed than is possible with coarsely scaled data (e.g., annually resolved total catches aggreg…

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 …

Mussels as a model system for integrative ecomechanics.

2015

Copyright © 2015 by Annual Reviews. All rights reserved. Mussels form dense aggregations that dominate temperate rocky shores, and they are key aquaculture species worldwide. Coastal environments are dynamic across a broad range of spatial and temporal scales, and their changing abiotic conditions affect mussel populations in a variety of ways, including altering their investments in structures, physiological processes, growth, and reproduction. Here, we describe four categories of ecomechanical models (biochemical, mechanical, energetic, and population) that we have developed to describe specific aspects of mussel biology, ranging from byssal attachment to energetics, population growth, an…