Search results for "plank"
showing 10 items of 578 documents
Particulate Organic Matter Composition in A Semi-Enclosed Marine System
2001
Spatial and temporal changes in the biochemical composition of particulate organic matter in a semi-enclosed marine system (Stagnone di Marsala, Mediterranean Sea) were studied, on a monthly basis, from January to December 1994, in order to assess nutritional value of suspended particles for benthic suspension feeders. According to previous findings, the study site displayed a strong oligotrophy. Chlorophyll-a accounted for a very low fraction of the total suspended matter pool (0.1%), whereas at least 75% of POC was of detrital/heterotrophic origin. POC: PON ratio values indicate that bacterioplankton biomass accounted for a significant fraction of the total POC pool, displaying values com…
The effect of fish farming organic waste on food availability for bivalve molluscs (Gaeta Gulf, Central Tyrrhenian, MED): stable carbon isotopic anal…
2001
Stable carbon isotope (δ13C) analysis was used in a fish-farming impacted Mediterranean area (the Gulf of Gaeta, Central Tyrrhenian) to determine the predominant carbon sources available to bivalve molluscs cultivated around fish cages. Wether the organic matter generated by fish farming was taken up by the bivalve molluscs was also investigated. Stable carbon isotope values were measured in the particulate organic carbon (POC) of samples from potential organic matter sources such as fish-pelleted feed, mollusc faecal waste and bivalve flesh. The sources of organic matter affecting the study area water column and benthic communities appeared to be terrigenous-continental, autochthonous (phy…
Effects of fish farming waste to sedimentary and particulate organic matter in a southern Mediterranean area (Gulf of Castellammare, Sicily): a multi…
2004
Abstract Carbon and nitrogen stable isotope analysis was used to investigate the dispersion area of waste material coming from fish farming activities in the western Mediterranean. Tests were conducted to see if uneaten feed and faecal material isotopic signals, originating from fish farms, could be detected in particulate organic matter (POM) and sedimentary organic matter (SOM). The detectable dispersion distance (from under cages as far as 1000 m) of cage-derived organic material was also examined. To do this, carbon (δ13C) and nitrogen (δ15N) composition in POM and SOM collected around the cages, in some control areas and in the waste material, was measured. Mean POM δ13C was −22.9±0.2‰…
Planktothrix rubescens in freshwater reservoirs: remote sensing potentiality for mapping cell density
2012
Planktothrix rubescens is sadly famous for producing microcystins (MCs), which are powerful hepatotoxins. During the winter 2005/06, P. rubescens has been found in the Pozzillo, Nicoletti, Prizzi and Garcia reservoirs, Sicily; in 2008 it was also detected in SS. Trinita di Delia and Castello reservoirs. Indeed, during periods of low shortwave irradiance such as winter, when light weakly penetrates water column and the water cools, P. rubescens filaments float up to the surface, forming red-colored blooms. Ancillary meteorological measurements highlighted low air temperatures between two frosts in December 2007 and February 2008, with a simultaneous reduction in the incoming total solar radi…
Planktothrix rubescens in freshwater reservoirs: The Sentinel-2 potentiality for mapping phycocyanin concentration
2012
In December 2006 blooms of Planktothrix rubescens were found in the Prizzi reservoir in Sicily. P. rubescens is sadly famous for producing microcystins (MC), which are harmful hepatotoxins. Recently (2006) P. rubescens has been found in the Pozzillo, Nicoletti, Ancipa, Prizzi and Garcia reservoirs. This paper compares the optical properties of the water of an infested reservoir and those of a clear water reservoir. Furthermore it evaluates an empirical method based on bands product to evaluate the phycocyanin cell density from MODIS, Landsat ETM+ and Sentinel-2 images. Spectroradiometric field campaigns were carried out in February/March 2008 to quantify the spectral transparencies of two w…
Disentangling conditional effects of multiple regime shifts on Atlantic cod productivity
2020
AbstractRegime shifts are increasingly prevalent in the ecological literature. However, definitions vary, and many detection methods are subjective. Here, we employ an operationally objective means of identifying regime shifts, using a Bayesian online change-point detection algorithm able to simultaneously identify shifts in the mean and(or) variance of time series data. We detected multiple regime shifts in long-term (59-154 years) patterns of coastal Norwegian Atlantic cod (>70% decline) and putative drivers of cod productivity: North Atlantic Oscillation (NAO); sea-surface temperature; zooplankton abundance; fishing mortality (F). The consequences of an environmental or climate-relate…
Heterogeneous vertical structure of the bacterioplankton community in a non-stratified Antarctic lake
2013
10 páginas, 4 figuras, 2 tablas.
Comparing biological classifications of freshwater phytoplankton: a case study from South China
2012
The use of ecological classification systems is becoming more and more widely used when studying phytoplankton. Grouping phytoplankton species into ecologically coherent groups allow to reduce redundancy and in this way, to handle a minor number of biological variables when investigating the ecological status of aquatic ecosystems. Three ecological classifications are mostly used when freshwater phytoplankton is studied: functional groups or coda, morpho-functional groups (MFGs) and morphology-based functional groups (MBFGs). In this study, these three ecological classifications were comparatively used along with two taxonomic classifications based on species and genera to analyse phytoplan…
Speciation in monogonont rotifers
1997
Monogonont rotifers are cyclical parthenogens livingin limnic habitats with considerable seasonalvariation and often with island-like features. Theoccurrence of bisexual reproduction in these organismsmakes it feasible to define ’fields for generecombination‘, i.e. biological species. In thispaper, we analyze the structure of the diversity inmonogonont rotifers using several data sets: taxonomicand intraspecific diversity as reported inidentification keys, morphological variation reportedin ecological studies, and allozyme and matingbehavior patterns. Our analysis suggests that siblingspecies may be frequent in rotifers. Monogonontrotifers seem to meet conditions for an activespeciation, wh…
Phylogenetic analysis of cryptic speciation in the polychaetePygospio elegans
2012
Development in marine invertebrate species can take place through a variety of modes and larval forms, but within a species, developmental mode is typically uniform. Poecilogony refers to the presence of more than one mode of development within a single species. True poecilogony is rare, however, and in some cases, apparent poecilogony is actually the result of variation in development mode among recently diverged cryptic species. We used a phylogenetic approach to examine whether poecilogony in the marine polychaete worm, Pygospio elegans, is the result of cryptic speciation. Populations of worms identified as P. elegans express a variety of developmental modes including planktonic, broode…