Search results for "Oceano"
showing 10 items of 1626 documents
Nitrate uptake rates in freshwater plankton: the effect of food web structure
2008
9 pages, 3 figure, 1 table
Long-term zoobenthos variability in the Gulf of Riga in relation to climate variability
2001
Abstract Macrozoobenthos data were collected three times a year from 1979 to 1996 in the Gulf of Riga, Eastern Baltic Sea. Interannual variability of the abundance and biomass of benthic fauna at coastal and offshore areas was related to climate variability using a multivariate regression model. The results suggest that the interannual variability of macrozoobenthos biomass at the offshore station in spring is controlled by the climate variability during winter-time. No correlations to large-scale climate pattern have been detected for other seasons and for the coastal region. An analysis of river runoff, nitrogen, and phosphorus data of the River Daugava indicates that the anthropogenic in…
Southern Ocean areas of endemism: a reanalysis using benthic hydroids (Cnidaria, Hydrozoa)
2013
The biogeographic history of the Southern Ocean (SO) fauna is complex and poorly studied, especially the areas of endemism. We reanalyzed the data of Marques & Peña Cantero (2010), along with other geographical records of endemic benthic hydroids below 45°S. A Parsimony Analysis of Endemicity (PAE) based on 5° latitude by 5° longitude matrix with 61 species resulted in eight areas of endemism. We discuss these results in the context of different hypotheses of the evolution of the SO fauna and previously proposed biogeography patterns.
Calcification is not the Achilles' heel of cold-water corals in an acidifying ocean
2015
Ocean acidification is thought to be a major threat to coral reefs: laboratory evidence and CO2 seep research has shown adverse effects on many coral species, although a few are resilient. There are concerns that cold-water corals are even more vulnerable as they live in areas where aragonite saturation (?ara) is lower than in the tropics and is falling rapidly due to CO2 emissions. Here, we provide laboratory evidence that net (gross calcification minus dissolution) and gross calcification rates of three common cold-water corals, Caryophyllia smithii, Dendrophyllia cornigera, and Desmophyllum dianthus, are not affected by pCO2 levels expected for 2100 (pCO2 1058 ?atm, ?ara 1.29), and nor a…
A new shoreline change assessment approach for erosion management strategies
2022
Shoreline evolution studies are fundamental to assess the rate of beach accretion or retreatment. In the last years, researchers developed many methods with several techniques belonging to different disciplines and backgrounds. Nowadays, the Shoreline Change Analysis (SCA) is the most widespread method to assess shoreline evolution. In fact, the SCA is needed to perform management strategies able to respond to current erosion or potential future erosion problems. This paper presents a new approach using an automatic method for SCA with accuracy and speed improvements. Indeed, in the framework of the management of coastal erosion and to develop an adaptation plan to coastal hazards it is nec…
The impact of the Little ice age on coccolithophores in the central Mediterranea Sea
2010
The Little Ice Age (LIA) is the last episode of a series of Holocene climatic anomalies. There is still little knowledge on the response of the marine environment to the pronounced cooling of the LIA and to the transition towards the 20th century global warming. Here we present decadal-scale coccolithophore data from four short cores recovered from the central Mediterranean Sea (northern Sicily Channel and Tyrrhenian Sea), which on the basis of <sup>210</sup>Pb activity span the last 200–350 years. The lowermost part of the record of one of the cores from the Sicily Channel, Station 407, which extends down to 1650 AD, is characterized by drastic changes in productivity. Specific…
Abundance and Distribution Patterns of Thunnus albacares in Isla del Coco National Park through Predictive Habitat Suitability Models
2016
Information on the distribution and habitat preferences of ecologically and commercially important species is essential for their management and protection. This is especially important as climate change, pollution, and overfishing change the structure and functioning of pelagic ecosystems. In this study, we used Bayesian hierarchical spatial-temporal models to map the Essential Fish Habitats of the Yellowfin tuna (Thunnus albacares) in the waters around Isla del Coco National Park, Pacific Costa Rica, based on independent underwater observations from 1993 to 2013. We assessed if observed changes in the distribution and abundance of this species are related with habitat characteristics, fis…
Phytoplankton equilibrium phases during thermal stratification in a deep subtropical reservoir
2008
SUMMARY 1. Equilibrium and non-equilibrium hypotheses have often been used to explain observations in community ecology. Published case studies have demonstrated that steady state phytoplankton assemblages are more likely to occur in deep lakes than in shallow mixed ones. 2. Phytoplankton seasonal succession was studied by weekly sampling in Faxinal Reservoir (S Brazil), a subtropical deep, clear, warm monomictic and slightly eutrophic reservoir. This study demonstrated an alternation of steady and non-steady state phases of phytoplankton assemblages with different dominant species during the steady states. 3. During the studied period, three steady states were identified with different dom…
Where do recruits come from? Backward Lagrangian simulation for the deep water rose shrimps in the Central Mediterranean Sea
2022
Backward-in-time Lagrangian dispersion models can efficiently reconstruct drifters trajectories by linking known arrival positions to potential sources. This approach was applied to the deep water rose shrimp (Parapenaeus longirostris) in the Strait of Sicily (central Mediterranean Sea). The objective was to identify the potential spawning areas of the larvae that settle in the known nursery grounds of the northern sector of the Strait of Sicily, thus quantifying the extent of the potential contribution to recruitment from the surrounding regions. Numerical simulations were performed over 11 years (2005–2015) and for two different periods (spring/summer and autumn/winter) corresponding to t…
Meeting the environmental challenge of port growth: A critical appraisal of the contingent valuation method and an application to Valencia Port, Spain
2012
In order to support effective policy-making, this research is aimed to emphasise the need of measuring the negative impact - or external costs - resulting from port growth. Considering the non-market nature of these external costs, a critical appraisal of the Contingent Valuation method is made paying special attention to the problem of hypothetical bias and the suitability of a willingness to accept (WTA) scenario for damage assessment. Finally, the results of a case study, conducted in Valencia (Spain), are presented with the intention of paving the way for future research in this specific context of port growth and negative externalities. In particular, results indicate that the average …