Search results for "plank"
showing 10 items of 578 documents
Distribution and seasonal dynamics of Cryptomonads in Sicilian water bodies
2003
Several species with a relevant ecological importance belong to Cryptophyta. Nevertheless, species-level identification from microscopic observations is problematic, lacking recent taxonomic keys. In this study we report our observations on distribution and seasonal dynamics of Cryptomonads in 33 Sicilian water bodies, as well as the main taxonomical problems we encountered. Species of the genera Cryptomonas and Plagioselmis are the most common in the examined water bodies. Their biomass seasonal trends usually show a peak in late winter and early spring. In advanced spring, and also in summer, due to the higher grazing pressure, the Cryptomonads biomass reaches its lowest values. Moreover,…
Phytoplankton distribution along trophic gradients within and among reservoirs in Catalonia (Spain)
2008
SUMMARY 1. Longitudinal gradients in the epilimnetic waters of stratified reservoirs provide a useful database to study changing environmental conditions. The spatial distribution, assemblage structure and specific adaptations of phytoplankton assemblages can be analysed along these gradients over short time scales. 2. Four reservoirs with a similar typology, located along an altitudinal gradient in the same eco-region, were sampled along their longitudinal axes. In total, 19 sampling stations provided a trophic spectrum, ranging from oligo-mesotrophy to hypertrophy, which was quantified by calculating the trophic state index of each sampling station in the four reservoirs. 3. Several patte…
Mesocosm experiments on nutrient and fish effects on shallow lake food webs in a Mediterranean climate
2004
Summary 1. Nutrient and fish manipulations in mesocosms were carried out on food-web interactions in a Mediterranean shallow lake in south-east Spain. Nutrients controlled biomass of phytoplankton and periphyton, while zooplankton, regulated by planktivorous fish, influenced the relative percentages of the dominant phytoplankton species. 2. Phytoplankton species diversity decreased with increasing nutrient concentration and planktivorous fish density. Cyanobacteria grew well in both turbid and clear-water states. 3. Planktivorous fish increased concentrations of soluble reactive phosphorus (SRP). Larger zooplankters (mostly Ceriodaphnia and copepods) were significantly reduced when fish wer…
Differential attributes of phytoplankton across the trophic gradient: a conceptual landscape with gaps
1998
I provide a conceptual landscape of attributes of phytoplankton related to trophic gradients, by reviewing 69 papers and books on eutrophication, with special reference to the ecology of the phytoplankton. Forty-eight ecological variables such as total phosphorus and Chl-a, are used, each related to the trophic gradient measured. They are subdivided in structural features of the phytoplankton, functional or dynamic features, and other relevant properties of the plankton community. Only twelve of the forty-eight variables are statistically related to trophic gradient. In most cases, variability across a trophic gradient is only nominally described. Less attention is given to functional, stru…
Ecological indicators – Schrödinger Ratio
2008
INTEGRATED CALCAREOUS PLANKTON BIOSTRATIGRAPHY OF SELECTED MIOCENE SUCCESSIONS IN THE NORTHERN CALABRIA (ITALY).
2005
An integrated calcareous plankton biostratigraphic approach on six sections cropping out in Northern Calabria allowed to define a revised chronostratigraphic framework for Tortonian-Messinian deposits. Four sections have been investigated in the Amantea Basin (Timpone Napoli, Vallone Salina, Case Vespano, and Cozzo Salice) and two in the Rossano Basin (Vallone Casino and Cozzo Sant'Isidoro). Biostratigraphic analyses have been based on quantitative counting of planktonic foraminifers and semiquantitative counting of nannofossils. The Timpone Napoli and Vallone Salina sections are Late Tortonian in age and referable to the Globorotalia suterae Zone. In terms of nannofossils zonal scheme thes…
Tracing the fate of microplastic carbon in the aquatic food web by compound-specific isotope analysis
2019
Increasing abundance of microplastics (MP) in marine and freshwaters is currently one of the greatest environmental concerns. Since plastics are fairly resistant to chemical decomposition, breakdown and reutilization of MP carbon complexes requires microbial activity. Currently, only a few microbial isolates have been shown to degrade MPs, and direct measurements of the fate of the MP carbon are still lacking. We used compound-specific isotope analysis to track the fate of fully labelled 13C-polyethylene (PE) MP carbon across the aquatic microbial-animal interface. Isotopic values of respired CO2 and membrane lipids showed that MP carbon was partly mineralized and partly used for cell growt…
Integrated annual calcium carbonate production of planktic calcifiers in the North Pacific from the R/V Kilo Moana cruise KM1712
2022
This dataset compiles the estimates of annual CaCO3 production, including the upper and lower limits of the estimates, for the 4 planktic calcifying groups considered in the study, the pteropods (mg/m²/yr), the heteropods (mg/m²/yr), the foraminifers (mg/m²/yr) and the coccolithophores (mg/m²/yr). The estimates derived from the living standing stocks of these 4 groups of organisms collected in the North Pacific between Hawaii and the Gulf of Alaska during the R/V Kilo Moana cruise KM1712 in August 2017. R code was used to calculate the integrated annual CaCO3 production for the different organisms, including the upper and lower limits (Gray, 2022).
Latvijas ūdeņu vides pētījumi un aizsardzība: referātu tēžu krājums (Rīga, 2015. gada 4. februāris)
2015
Observations on mucus aggregates along Sicilian coasts during 1991–1992
1995
Abstract The results of some observations on gelatinous material accumulating on the sea ground and free floating in the water column along Sicilian coasts are reported. The phenomenon showed different development patterns moving from the Tyrrherian to the Jonian coast and to the Sicilian Channel. Moreover, in 1991, mucus aggregates in the Tyrrhenian sea showed a similar structure, behaviour and origin to those observed in the Adriatic sea, whereas, in 1992, only a massive growth of metaphytic threadlike algae, more or less producing gelatinous sheaths, occurred.