Search results for "Systematics"
showing 10 items of 6702 documents
Effect of the presence of the shore crab, Carcinus maenas, on the burrowing behaviour and clearance rate of the common cockle, Cerastoderma edule
2011
Bivalves demonstrate various morphological and behavioural adaptations to reduce the risk of being attacked by predators. This paper examines how the presence of the crab Carcinus maenas (L.), a natural predator of the cockle Cerastoderma edule (L.), affects its burrowing depth and clearance or feeding rate. Cockles were placed in experimental tanks and treated with three levels of predatory disturbance: (1) unfed crab loose inside the tank, (2) unfed crab inside a cage suspended in the water column and (3) no crab present. Cockles’ burrowing depth was measured in two sediment types: mud and sand. Cockles burrowed more deeply in treatments with no crabs. Burrowing depth in sand was signific…
Filtration pressure by bivalves affects the trophic conditions in Mediterranean shallow ecosystems
2009
Bivalve filtration may control the amount of seston in coastal waters, reducing local euthrophication and keeping degrading phenomena like hypoxia and anthropogenic pollution under control. Two Sicilian brackish-marine ponds (Ganzirri and Faro) present us with the opportunity to gain data on the effect of bivalve filtration on the amount of particulate organic matter in the field. The cultivation of bivalves has been carried out in both of the ponds since the early 1990s but stopped in Ganzirri in 1995.We tested whether the cessation of bivalve cultivation influenced features of organic matter available to suspension feeders (total suspended matter, its inorganic and organic fractions, chlo…
Do island plant populations really have lower genetic variation than mainland populations? Effects of selection and distribution range on genetic div…
2015
Ecological and evolutionary studies largely assume that island populations display low levels of neutral genetic variation. However, this notion has only been formally tested in a few cases involving plant taxa, and the confounding effect of selection on genetic diversity (GD) estimates based on putatively neutral markers has typically been overlooked. Here, we generated nuclear microsatellite and plastid DNA sequence data in Periploca laevigata, a plant taxon with an island–mainland distribution area, to (i) investigate whether selection affects GD estimates of populations across contrasting habitats; and (ii) test the long-standing idea that island populations have lower GD than their mai…
The role and contribution of the seagrass Posidonia oceanica (L.) Delile organic matter for secondary consumers as revealed by carbon and nitrogen st…
2002
The δ13C and δ15N values of primary producers and consumers were studied to obtain information on the trophic role of Posidonia oceanica L. Delile, the dominant primary producer, in a Mediterranean shallow environment (the Stagnone di Marsala, western Sicily). δ13C strongly discriminated between pelagic and benthic pathways, with the former based on phytoplankton and the latter on a mixed pool of seagrass detritus, epiphytes and benthic algae as carbon sources. A particularly important trophic role appears to be performed by the vegetal epiphytic community on seagrass leaves (δ13C = -14.9 ± 0.1‰), which supports most of the faunal seagrass community (i.e. Amphipoda, Isopoda, Tanaidacea; δ13…
Life history traits to predict biogeographic species distributions in bivalves
2015
Organismal fecundity (F) and its relationship with body size (BS) are key factors in predicting species distribution under current and future scenarios of global change. A functional trait-based dynamic energy budget (FT-DEB) is proposed as a mechanistic approach to predict the variation of F and BS as function of environmental correlates using two marine bivalves as model species (Mytilus galloprovincialis and Brachidontes pharaonis). Validation proof of model skill (i.e., degree of correspondence between model predictions and field observations) and stationarity (i.e., ability of a model generated from data collected at one place/time to predict processes at another place/time) was provid…
Dynamic Energy Budget parameters of Brachidontes pharaonis, a lessepsian bivalve in the Mediterranean Sea.
2014
Dynamic Energy Budget (DEB) models are used for describing the flow of energy through organisms. The most important and powerful aspect of DEB theory is that inter-specific differences can be captured in the same model by comparison of parameter values. However, estimation of these parameters is complicated and can often not be done with direct empirical measurements alone. Here, we present DEB parameter estimates obtained by combining both experimental and literature data for the filter feeder Brachidontes pharaonis, which is considered one among the 100 worst invasive marine species in the Mediterranean Basin. We utilize a statistical procedure based on the covariation method to obtain pa…
Individual and population-scale carbon and nitrogen isotopic values of Procambarus clarkii in invaded freshwater ecosystems
2022
Este artículo contiene 16 páginas, 1 figura, 1 tablas.
Predicting biological invasions in marine habitats through eco-physiological mechanistic models: a case study with the bivalveBrachidontes pharaonis
2013
Aim We used a coupled biophysical ecology (BE)-physiological mechanistic modelling approach based on the Dynamic Energy Budget theory (DEB, Dynamic energy budget theory for metabolic organisation, 2010, Cambridge University Press, Cambridge; DEB) to generate spatially explicit predictions of physiological performance (maximal size and reproductive output) for the invasive mussel, Brachidontes pharaonis. Location We examined 26 sites throughout the central Mediterranean Sea. Methods We ran models under subtidal and intertidal conditions; hourly weather and water temperature data were obtained from the Italian Buoy Network, and monthly CHL-a data were obtained from satellite imagery. Results …
Seasonal variations in the stable carbon and nitrogen isotope ratios (13C/12C and 15N/14N) of primary producers and consumers in a western Mediterran…
2003
Stable carbon and nitrogen isotope ratios (13C/12C and 15N/14N) of primary producers and consumers were investigated seasonally throughout 1999, in order to describe the food web in a western Mediterranean coastal lagoon (Lake of Sabaudia, central Italy). Particulate organic matter and algal material (seagrass epiphytes and macroalgae) seem to constitute the main food sources for primary consumers (zooplankton and small benthic invertebrates, respectively) throughout the sampling year, while the seagrass Cymodocea nodosa appears to play a negligible trophic role. As regards the ichthyofauna, carbon stable isotopes differentiated between planktivore and benthivore fish species. However, a be…
The first confirmed record of the Atlantic blue crab Callinectes sapidus Rathbun, 1896 (Decapoda, Brachyura) from Maltese waters
2022
The invasive portunid species Callinectes sapidus is hereby recorded for the first time from Maltese waters, thus updating the known distribution of this decapod of Atlantic origin within the Mediterranean. Potential introduction pathways of the species to Maltese waters are discussed.