Search results for "Detritus"
showing 10 items of 39 documents
Experimental Study on the Diet of Mosquitofish (Gambusia holbrooki) under Different Ecological Conditions in a Shallow Lake
2004
We studied the diet of the eastern mosquitofish Gambusia holbrooki with in situ experimental mesocosms located in a shallow lake. Different nutrient concentrations (phosphorus and nitrogen) and fish population densities were tested. Our results confirm that it is a planktivorous species, with also a great ingestion of algae and detritus. Nutrient fertilization caused almost no changes in this species feeding behavior, but larger mosquitofish stocks induced a shift to zooplanktivory and a decline in detritivory. When macrophytes were present, the predation effect focused on zooplankton and plant-associated animals, otherwise predation on bottom macroinvertebrates increased. Females preyed up…
Utilization of muddy detritus as organic matter source by the fan mussel Pinna nobilis.
2014
The knowledge of the feeding habits in marine species is fundamental to better understand their relationship with the environment. Although phytoplankton has been traditionally reported as the main food source consumed by the Mediterranean fan mussel Pinna nobilis, recent studies have revealed that detritus represents an important food source for this species. We analysed the degree of acceptance of muddy detritus and the utilisation of its organic matter (OM) by P. nobilis on a group of 21 individuals (30.3-59.7 cm of total shell height (Ht)). The specimens were collected between July and September 2012 in two areas (43°04´25” N; 5°46´7” E and 43°04´34” N; 5°47´32” E) of the Embiez archipe…
MARIOLA: a model for calculating the response of mediterranean bush ecosystem to climatic variations
1995
Abstract The paper summarizes the bush ecosystem model developed for assessing the effects of climatic change on the behaviour of mediterranean bushes assuming that temperature, humidity and rain-fall are the basic dimensions of the niche occupied by shrub species. In this context, changes in the monthly weather pattern serve only to outline the growth conditions due to the nonlinearity of response of shrubs to climatic factors. The plant-soil-atmosphere system is described by means of ordinary non-linear differential equations for the state variables: green biomass, woody biomass, the residues of green and woody biomasses, faecal detritus of mammals on the soil, and the total organic matte…
Analysis of the trophic role of Mediterranean seagrasses in marine coastal ecosystems: a review
2009
Abstract Seagrasses form high-productivity coastal ecosystems, providing habitats for many organisms, including species of commercial value. They play a significant role as a direct food source for herbivores and also enter detrital food webs. In this review, the trophic ecology of Mediterranean seagrass ecosystems is revised, with major emphasis on Posidonia oceanica, the most extensively studied seagrass. The major topics are the role of herbivory and detritus, the contribution to littoral fish production, exportation to other ecosystems and the seagrass role as a vector of anthropogenic nutrients into food webs. Topics are discussed by analysing both conventional knowledge and new insigh…
Environmental Constraints on Pathways of Organic Detritus in a Semi-enclosed Marine System (W-Mediterranean)
2001
In order to assess seasonal and spatial changes in water-sediment interaction processes in a semi-enclosed marine system of Western Sicily (Marsala lagoon; W-Mediterranean), the biochemical composition of suspended and sediment organic matter was studied, during a one-year sampling period. The observed dynamic balance of resuspension vs. sedimentation processes and the macroalgal and vascular plant coverage appear major factors in affecting both amounts and biochemical composition of suspended and sedimentary organic matter and allowed us to identify two different sub-systems. The northern area, characterised by frequent wind-induced sediment resuspension events and by a scant vegetation, d…
Geochemical constraints on the provenance and depositional setting of sedimentary rocks from the islands of Chios, Inousses and Psara, Aegean Sea, Gr…
2007
The provenance and depositional setting of Late Palaeozoic and Early Mesozoic clastic sediments from the eastern Aegean archipelago are examined here for the first time using whole-rock geochemistry and composition of detrital chrome spinel. Major- and trace-element data for Late Palaeozoic and Permo-Triassic clastic sediments from the Lower and Upper Units of Chios are compatible with an acidic to intermediate source, minor input of (ultra)mafic detritus and recycling of older sedimentary components. Chondrite-normalized REE profiles are uniform with light REE enrichments (La N /Yb N c . 7.7), negative Eu anomalies (Eu/Eu* c . 0.67) and flat heavy REE patterns (Gd N /Yb N c . 1.5), indicat…
Estimation of the volume of Posidonia oceanica detritus accumulations along Sicilian coasts by using very high resolution images
2019
Posidonia oceanica meadows are among the most important marine coastal ecosystems in the Mediterranean Sea due to several roles they are able to play. They, in fact, support high levels of primary production, enhance sedimentation of suspended particles through their canopies, prevent resuspension of marine sediments by means of roots and rhizomes and counteract coast erosion. Part of the primary production of this seagrass is not transferred to herbivores either immediately to detritus pathway but it can accumulate on the shore in form of banquette, typical structures exerting a significant role in protection of beaches from erosion. To accurately measure the extension, morphology, volume …
Quali-quantitative assessment of Posidonia oceanica detritus accumulations in pocket-beaches with different productivity levels of nearshore seagrass…
2019
Posidonia oceanica detritus accumulates in late summer-autumn along the coasts forming beach-cast seagrass wracks known as banquette. Although seagrass wracks are highly variable at both spatial and temporal scales, they have an important ecological role as they protect the coast from erosion, support beach biodiversity and trophic webs and supply nutrients to dune vegetation. Previous studies have focused mainly on the beach-cast morphological characterization and variability, as well as on associated biotic communities. However, few studies have focused on the quali-quantitative assessment of seagrass wracks. The aim of this study was to assess the spatial variability of the P.oceanica be…
40Ar/39Ar laser probe dating of detrital white micas from Cretaceous sedimentary rocks of the Eastern Alps: Evidence for Variscan high-pressure metam…
1997
The detritus of Cretaceous synorogenic sandstones of the northern margin of the Austroalpine microplate contains evidence for a high-pressure metamorphic basement and obducted oceanic crust exposed in early Alpine time. 40 Ar/ 39 Ar laser-probe data of detrital white micas give excellent plateau ages in a narrow range from 320 to 360 Ma. White micas cover the whole range from muscovites up to phengites (3.04 to 3.48 Si per formula unit). Heavy mineral spectra contain chrome spinel, glaucophane, chloritoid, epidote, and garnet, as well as zircon, tourmaline, and rutile. Glaucophane, chloritoid, and phengite correlate in their abundance. These minerals also correlate positively with the stabl…
Indo-Antarctic derived detritus on the northern margin of Gondwana: evidence for continental-scale sediment transport
2013
Provenance studies from Cambro-Ordovician sediments of the North Gondwana passive margin typically ascribe a North African source, a conclusion that cannot be reconciled with all observations. We present new U-Pb ages from detrital rutile and zircon from Late Ordovician sediments from Saxo-Thuringia, Germany. Detrital zircons yield age populations of 500–800 Ma, 900–1050 Ma and 1800–2600 Ma. The detrital rutile age spectra are unimodal with ages between 500 and 650 Ma and likely represent, together with the 500–800 Ma and 1800–2600 Ma zircon populations, detritus sourced predominantly from North Africa. In contrast, the c. 950 Ma zircons, which are persistently found in Cambro-Ordovician se…