Qualidade da solha selvagem e criada em circuito fechado e aberto

Mestrado em Ciências do Mar e Zonas CosteirasSoles (Solea spp) are a high-value commercial group of species with increasing importance in aquaculture. Common quality evaluation methods were used to compare Solea solea and Solea senegalensis sampled from the natural environment and fish farms. The aim was to develop a series of experiments and analysis of wild and farmed fish in Portugal, during 31 days, during boxed and iced storage. The analyses were performed using physical evaluations with Torrymeter type 295 and RT-Freshmeter type RT-2E, each 2 days and sensory evaluations using QIM (Quality Index Method), every day. The results show that farmed fish has a slower decrease in instrumentally-measured properties than the farmed, and QIM results show a loss in appearance more evident in the wild samples. For more accurate results, complementary analysis, like chemical, histological and microbiological, become necessary.As solhas (Solea spp) são um grupo de espécies de alto valor comercial com crescente importância na aquicultura. Métodos de avaliação da qualidade comuns em pescado foram usados para comparar a qualidade da solha. Solea solea e Solea senegalensis foram amostrados do ambiente natural e aquiculturas. Os peixes passaram por uma série de testes com o objetivo de analisar a sua qualidade. As amostras de peixes selvagens e de cultura, obtidas em Portugal, foram analisadas durante 31 dias, ao longo da sua degradação em caixas e em gelo moído. Foram feitas avaliações com os aparelhos Torrymeter 295 e RT-Freshmeter RT-2E, a cada dois dias, e avaliações sensoriais com o esquema QIM (Quality Índex Method), todos os dias. Os resultados mostram que os peixes de aquacultura têm uma perda mais lenta de qualidade do que os selvagens, em ambas as análises instrumentais, e nas análises do QIM mostram uma perda de qualidade na aparência mais evidente nos os selvagens. Para resultados mais precisos, análises complementares, como químicas, histológicas, e microbiológicas, tornam-se necessárias

Influence of Ocean Acidification on a Natural Winter-to-Summer Plankton Succession : First Insights from a Long-Term Mesocosm Study Draw Attention to Periods of Low Nutrient Concentrations

Every year, the oceans absorb about 30% of anthropogenic carbon dioxide (CO2) leading to a re-equilibration of the marine carbonate system and decreasing seawater pH. Today, there is increasing awareness that these changes-summarized by the term ocean acidification (OA)-could differentially affect the competitive ability of marine organisms, thereby provoking a restructuring of marine ecosystems and biogeochemical element cycles. In winter 2013, we deployed ten pelagic mesocosms in the Gullmar Fjord at the Swedish west coast in order to study the effect of OA on plankton ecology and biogeochemistry under close to natural conditions. Five of the ten mesocosms were left unperturbed and served as controls (similar to 380 mu atm pCO(2)), whereas the others were enriched with CO2-saturated water to simulate realistic end-of-the-century carbonate chemistry conditions (mu 760 mu atm pCO(2)). We ran the experiment for 113 days which allowed us to study the influence of high CO2 on an entire winter-to-summer plankton succession and to investigate the potential of some plankton organisms for evolutionary adaptation to OA in their natural environment. This paper is the first in a PLOS collection and provides a detailed overview on the experimental design, important events, and the key complexities of such a "long-term mesocosm" approach. Furthermore, we analyzed whether simulated end-of-the-century carbonate chemistry conditions could lead to a significant restructuring of the plankton community in the course of the succession. At the level of detail analyzed in this overview paper we found that CO2-induced differences in plankton community composition were non-detectable during most of the succession except for a period where a phytoplankton bloom was fueled by remineralized nutrients. These results indicate: (1) Long-term studies with pelagic ecosystems are necessary to uncover OA-sensitive stages of succession. (2) Plankton communities fueled by regenerated nutrients may be more responsive to changing carbonate chemistry than those having access to high inorganic nutrient concentrations and may deserve particular attention in future studies.Peer reviewe

Enhancement of fish communities, improvement of sampling and stock assessment in lakes and reservoirs.

This Ph.D. thesis focuses on fish habitats, how we can improve their natural complexity, and how we can improve techniques to survey these habitats. With increasing human activities affecting freshwater ecosystems due to human population growth and industrial expansion, it is crucial to study environmental changes, their impacts, and ways to mitigate damage. As many biotic and abiotic factors can influence the health and diversity of the community, for our study, we focused on habitat definition and complexity, and the effect of fishery management. Paper (I) focuses on the transition between littoral (shallow areas) and pelagic (open water) habitats and their impact on fish communities. The littoral zone, typically the most intricate segment of a water body, serves as the primary habitat for a significant portion of the fish community and species diversity. However, its spatial extent is very limited. Littoral delimitation is important for obtaining a true picture of the fish community composition and for its sustainable management decisions. Paper (II) investigated the impact of protected areas on fish populations in the Lipno reservoir in the Czech Republic, specifically focusing on the abundance, biomass, standard length, and diversity indices. Protected areas have legislation that reduces or stops certain anthropological impacts to help recover the ecosystem. These areas are normally linked to spawning areas, feeding grounds, or rare species and are vital for the restoration and proliferation of specific environments. In our case, we revealed more and larger predatory fish in protected and low anthropological impact areas. Paper (III) tests the introduction of artificial habitats, which are man-made structures or environments created to provide additional habitats and support for various organisms. Despite efforts to restore habitats to their natural states, there are instances where complete restoration is challenging. In particular, water bodies are subjected to significant anthropogenic alterations, such as reservoirs. In such instances, the introduction of artificial habitats has emerged as a solution to rapidly enhance the complexity of these environments. In Lipno reservoir, artificial floating islands attracted young-of-the-year of common species

Data presented in the paper "Marine virus predation by non-host organisms"

These experiments tested the effects of organisms which cannot become infected (non-hosts) on the reduction of free virus particals in a marine system. Individual organisms of a variety of species were placed in to aquaria filled with a known abundance of free virus particles. At the end of the experiment, the individual organisms were removed and the remaining viral particles were counted usin flowcytometry