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Gholami M.,Islamic Azad University at Tehran | Reza Fatemi S.M.,Islamic Azad University at Tehran | Fallahi M.,Institute of Aquaculture | Esmaeili Sari A.,Tarbiat Modares University | Mashinchian A.,Islamic Azad University at Tehran
Life Science Journal | Year: 2013

In this study, we investigated the individual and mixed effects of heavy metals (Cu and Cd) and detergent (LAS) on growth and reproduction of Scenedesmus obliquus algae. We have conducted several tests to determine acute toxicity of pollutants in algae in individual and mixed manners through Selenastrum bottle test method. We used five test samples and a control sample and repeated the tests three times. Concentration ranges were determined by the logarithmic method and finally, the obtained results were calculated by probit analysis and the values of correlation coefficient, EC, and LC (10, 50, and 90) for pollutants were obtained in individual and mixed manners. The results obtained in tests of acute toxicity of algae and values of EC(10, 50 and 90) from the individual effects of heavy metals (Cadmium and Copper), LAS detergent and mixed effects of (Cd and LAS) mixture and (copper and LAS) mixture were, respectively, as the following: Cd(0.068, 0.127, and 0.237), Cu (0.53, 1.5, and 4.24), LAS (10.40, 21.53, and 130), LAS + Cd (0.013, 0.066, and 0.33), LAS + Cu (0.035, 0.21, and 1.32). The obtained allowed limits were 0.0127, 0.15, 2.153, 0.0066, 0.021 mg per liter, respectively, with correlation coefficients of 92, 98, 93, 90 and 95 percent, respectively. According to the non-parametric test of Kruskal-Wallis at 95% of confidence level, we can conclude that, there is no significant difference between copper and mixture of copper and LAS in terms of the effects on algae (P < 0.05). In addition, according to the non-parametric test of Kruskal-Wallis at 95% of confidence level, we can conclude that, there is significant difference between LAS and mixture of LAS and copper in in terms of the effects on algae (P < 0.05).

Fortes N.R.,University of the Philippines in the Visayas | Pinosa L.A.G.,Institute of Aquaculture
Philippine Journal of Science | Year: 2010

The diversity, a univariate measure of both the number of genera present (richness) and their distribution (evenness), of the phytoperiphyton community of a brackishwater pond that received water from a river and the sea was studied during dry and wet seasons. The algal mat ("lab-lab") was sampled when the pond was filled to depths of 5, 10, 15, and 30 cm during 2 and 7 days of submergence to determine the effect of seasons, depth and submergence on the diversity and relate it to the trophic status of periphyton-based pond and quality of "lab-lab" as fish food. Generic diversity and evenness declined with increased depth and colonization time during the dry season but not during the wet season. Richness was affected by depth which was significantly different (p≤0.05) at 2 days submergence, and highly significant (p≤0.01) at 7 days submergence. The index of diversity was moderate ranging from 1.0-3.2 during dry season and 1.2-2.2 during wet season. Richness ranged from 0.7-1.4 during dry season and 0.7-1.0 during wet season. There were low stabilized genera with evenness that ranged from 0.3-0.5 during dry season and 0.2-0.5 during wet season. A more diverse community prevailed during the dry season than during the wet season due to differences in environmental conditions.

For the first time in fish, the team scientifically demonstrated that exposure to stress resulted in 'emotional fever' – where fish temporarily increased their body temperatures by up to four degrees Celsius by moving through a thermal gradient. Dr Sonia Rey, Research Fellow at the University of Stirling's Institute of Aquaculture said: "Our study reopens the discussion upon sentience in fish, which is fundamental to our knowledge of the species and their welfare. This will have a bearing on the development of future regulations and mitigation measures around fish. "With fish brains lacking a cerebral cortex, unlike mammals, birds and reptiles, it has been claimed to date that they have no consciousness. This research removes one of the key arguments underpinning that claim." The research, which focussed on zebrafish, also involved the Universitat Autònoma de Barcelona and the University of Bristol. It features in the journal Proceedings of the Royal Society B. Dr Rey said: "Fish cannot internally regulate their own body temperature. Rather, it equates to the temperature of the environment they are in, and so fish travel between different waters to attain their optimal temperature. "In our study we allowed the fish to choose their own temperature by providing them with a thermal gradient in which they could freely move between interconnected chambers holding water at varying degrees Celsius. "Groups of fish that had been gently submerged in a net for a short period chose to travel, when they were released back into the same temperature chamber, to warmer waters, where they then stayed for several hours. "This 'emotional fever' was the effect of their short confinement. Further studies are now needed to explore the underlying mechanisms of this stress-induced hyperthermia, and to test it against different stressors." Dr Simon MacKenzie, Reader in Marine Biotechnology at the Institute of Aquaculture, said: "Our study has significant impact upon our understanding of how fish use thermal choice to optimise their response to stress. This game changing observation will have far reaching implications in how we approach research in fish and how we consider their welfare." Explore further: Fish go deep to beat the heat

Doxa C.K.,Cretaquarium | Doxa C.K.,University of Crete | Sterioti A.,Cretaquarium | Sterioti A.,Institute of Aquaculture | And 3 more authors.
Journal of Biological Research | Year: 2011

In the present study the reproductive biology of Tonna galea (Linnaeus, 1758) was studied for the first time. In mid-September 2006 one individual was found laying a pale pink egg rosette of 39.5 cm length. Number of embryos, stages of development, shape and dimensions were studied in relation to time and measured on microphotographs of randomly sampled capsules. Each oval or spherical shaped capsule of 3.61 mm total length contained 101 developing embryos. The embryo diameter ranged from 297.5 μm of the unsegmented egg to 489 μm of the free veliger. At 21°C eclosion occurred 34 days after capsule deposition, at a free-swimming veliger stage. The duration of each developmental stage, from one cell to veliger, is reported. Results are discussed in relation to possible culture and use for ecological purposes.

Villasante S.,University of Santiago de Compostela | Rivero Rodriguez S.,University of Santiago de Compostela | Remiro J.,Spanish Aquaculture Observatory OESA Foundation | Garcia-Diez C.,Spanish Aquaculture Observatory OESA Foundation | And 7 more authors.
Ecosystem Services | Year: 2015

Despite the recognised advantages of rural aquaculture, little research has been done to assess its direct and indirect impacts on food security and poverty mitigation, especially in Africa. The aim of this study is to provide a better understanding of the role of fish-farming systems and their scale, market structure and institutional mechanisms in improving rural aquaculture in Mozambique and Namibia and, consequently, livelihoods and human development in rural communities.This study shows that rural households are strongly dependent on agriculture/aquaculture as their main source of food and income. In general, families making a living from fish farming as their main activity have improved their access to food and basic services. There has been a significant increase in fish consumption in households since they have been engaged in rural fish farming, and there has also been an increase in the frequency of fish consumption per week. This progress in food and nutrition security needs to be consolidated through fish-farming development policies. However, rural aquaculture is still a sector in the early stages of development and has to overcome limiting factors such as a lack of specialised technical knowledge, logistical infrastructure and difficulties in access to credit and markets. © 2015 Elsevier B.V.

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