Browsing by Author "Rocha, Rui J. M."
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- Development and validation of an experimental life support system for assessing the effects of global climate change and environmental contamination on estuarine and coastal marine benthic communitiesPublication . Coelho, Francisco J. R. C.; Rocha, Rui J. M.; Pires, Ana C. C.; Ladeiro, Bruno; Castanheira, Jose M.; Costa, Rodrigo; Almeida, Adelaide; Cunha, Angela; Lillebo, Ana Isabel; Ribeiro, Rui; Pereira, Ruth; Lopes, Isabel; Marques, Catarina; Moreira-Santos, Matilde; Calado, Ricardo; Cleary, Daniel F. R.; Gomes, Newton C. M.An experimental life support system (ELSS) was constructed to study the interactive effects of multiple stressors on coastal and estuarine benthic communities, specifically perturbations driven by global climate change and anthropogenic environmental contamination. The ELSS allows researchers to control salinity, pH, temperature, ultraviolet radiation (UVR), tidal rhythms and exposure to selected contaminants. Unlike most microcosms previously described, our system enables true independent replication (including randomization). In addition to this, it can be assembled using commercially available materials and equipment, thereby facilitating the replication of identical experimental setups in different geographical locations. Here, we validate the reproducibility and environmental quality of the system by comparing chemical and biological parameters recorded in our ELSS with those prevalent in the natural environment. Water, sediment microbial community and ragworm (the polychaete Hediste diversicolor) samples were obtained from four microcosms after 57days of operation. In general, average concentrations of dissolved inorganic nutrients (NO3-; NH4+ and PO4-3) in the water column of the ELSS experimental control units were within the range of concentrations recorded in the natural environment. While some shifts in bacterial community composition were observed between in situ and ELSS sediment samples, the relative abundance of most metabolically active bacterial taxa appeared to be stable. In addition, ELSS operation did not significantly affect survival, oxidative stress and neurological biomarkers of the model organism Hediste diversicolor. The validation data indicate that this system can be used to assess independent or interactive effects of climate change and environmental contamination on benthic communities. Researchers will be able to simulate the effects of these stressors on processes driven by microbial communities, sediment and seawater chemistry and to evaluate potential consequences to sediment toxicity using model organisms such as Hediste diversicolor.
- Phaeodactylum tricornutum biomass in microdiets enhances Senegalese sole (Solea senegalensis) larval growth performance during weaningPublication . Barreto, André; Pinto, Wilson; Rodrigues, Andreia; Rocha, Rui J. M.; Unamunzaga, Carlos; Silva, Tome; Dias, Jorge; Conceicao, LuisMicroalgae are one of the most promising groups of functional ingredients for inclusion in microdiets for Senegalese sole (Solea senegalensis) larvae, supplying components with anti-oxidant effects that may be important during an accelerated stage of development where excessive reactive oxygen substance production leading to oxidative stress may occur. The diatom Phaeodactylum tricornutum complies with such potential since it is rich in fucoxanthin, a carotenoid with demonstrated antioxidant activity. This study aimed at determining the effect of dietary P. tricornutum supplementation on the growth performance, survival and levels of oxidative stress of Senegalese sole postlarvae. Four dietary treatments were tested: a commercial microdiet, used as control, and three experimental variants where P. tricornutum was included (1) whole cells at 5%-WP5, (2) broken cells at 5%-BP5 and (3) broken cells at 10%-BP10. At the end of the trial, no significant differences were found in growth performance of larvae fed diets where P. tricornutum was included at 5% (WP5 and BP5) and the commercial control. However, larvae from the BP10 treatment had a significantly higher dry weight than larvae from the remaining treatments. Moreover, the experimental diets had no significant effects on oxidative stress. Nonetheless, lipid peroxidation levels were significantly higher in smaller larvae fed diets where P. tricornutum whole cells were included, relatively to the commercial control. The results of the present study demonstrate that P. tricornutum broken cell biomass has the potential for inclusion in weaning microdiets for Senegalese sole, increasing larval growth performance at an inclusion level of 10 %.
- Sustainable feed formulation to community‐based aquaculture: Oreochromis niloticus fingerlings performance and antioxidant statusPublication . Pires, Sílvia F. S.; Vital, Inês; Pereira, Vitória; Bustani, Henriques; Aragão, Cláudia; Engrola, Sofia; Cabano, Miguel; Dias, Jorge; Soares, Amadeu M. V. M.; Rodrigues, Andreia C. M.; Rocha, Rui J. M.Community-based aquaculture can reduce dependence on natural resources, promote biodiversity conservation, and improve local economies and food security. However, this activity is highly dependent on local conditions regarding natural resources, such as the availability of produced organisms, adequate feeds, and environmental factors. As ectothermic organisms, fish are more susceptible to temperature fluctuations in culture conditions. A set of raw ingredients (e.g., cassava and local beans) produced or available in villages from Cabo Delgado (Mozambique) with nutritional potential for fish feed were selected to produce an experimental diet. The following objectives were defined: (1) evaluate growth performance of tilapia fingerlings fed a diet produced with local ingredients, compared with a commercial-like diet; and (2) evaluate the response to thermal stress (18, 26, and 32degree celsius) by tilapia fingerlings fed with tested diets. Tilapia fed with an experimental diet presented lower growth rates, lower DNA damage, higher neurophysiological, and antioxidant activity, leading to increased oxidative stress. Regarding energy budget, tilapia fed with the experimental diet presented higher protein content at 26degree celsius and lipids at 18degree celsius, leading to greater energy available at these temperatures. Overall, local ingredients can be successfully used as an additional feed source for tilapia production in community-based aquaculture in earthen ponds.
- The effect of mixotrophy in the ex situ culture of the soft coral Sarcophyton cf. glaucumPublication . Costa, Ana P. L.; Calado, Ricardo; Marques, Bruna; Lillebo, Ana I.; Serôdio, João; Soares, Amadeu M. V. M.; Serrão, Ester; Rocha, Rui J. M.In toto aquaculture is a promising approach towards the bioprospecting and production of bioactive compounds from the coral holobiont. Coral aquaculture ex situ allows a better control of culture conditions to maximize coral growth and reduce production costs. Light (either the Photosynthetically Active Radiation-PAR, or the emitted spectrum) is one of the most important factors affecting the growth of symbiotic corals, due to their association with photosynthetic dinoflagellates. Additionally, the balance between autotrophy and heterotrophy is also known to play a key role in the successful growth of mixotrophic corals. The present study aimed to evaluate the effect of: 1) light spectrum (white and blue light), 2) PAR intensity (50 and 120 mu mol quanta m(-2) s(-1)), and 3) heterotrophic feeding (rotifers-Brachionus plicatilis), in the physiology, photobiology and growth of coral fragments obtained from three mother colonies of the mixotrophic soft coral Sarcophyton cf. glaucum, cultured ex situ in recirculated systems during 80 days. The supply of rotifers did not affect coral growth and promoted the increase of dissolved inorganic nitrogen and phosphorous concentrations (DIN and DIP, respectively) in the water column. Coral fragments originating from the different mother colonies presented distinct responses to the tested light PAR intensities and spectra, as well as to the interaction of these factors with the supply of rotifers. We concluded that the variability displayed between different mother colonies of the same species can affect the growth response of corals under contrasting scenarios of mixotrophy. Statement of relevance: Improvement of in toto aquaculture of Sarcophyton cf. glaucum. (C) 2015 Elsevier B.V. All rights reserved.