Growth and photosynthesis inhibition by agricultural pesticides in three freshwater microalgae.
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Growth rate and photosynthesis of Microcystis aeruginosa, Scenedesmus quadricauda and Aulacoseira granulata exposed to different concentrations of the agricultural pesticides CNP (p-nitrophenyl 2,4,6-trichlorophenyl ether), MEP [O,O-dimethyl O-(3-methyl-4-nitrophenyl) thiophosphate], ISP [isoprothiolane (C12H18O4S2)], and TBT (tri-n-butyltin chloride) were determined. The effective concentration (EC50) for growth and photosynthesis in each species of microalga was then calculated. Inhibition of growth and photosynthesis in the three microalgae was greatest when exposed to CNP and TBT. Microcystis aeruginosa and A. granulata showed a higher tolerance, whereas S. quadricauda showed a higher sensitivity. Except for MEP, the EC50 values for growth obtained in the three microalgae were higher than those for photosynthesis. The growth–photosynthesis response relationship showed that, for CNP and TBT, growth of the three organisms tested were less inhibited than their photosynthesis at a lower exposure (0.001–0.05 μg/L). At a higher exposure (0.10–1.0 μg/L), the response between relative growth rates and relative photosynthesis was proportional. For MEP and ISP, a proportional response existed between relative growth rates and relative photosynthesis in all test organisms. These results suggest that the inhibition of growth and photosynthesis by agricultural pesticides differs for the three microalgae. The differences can be explained in terms of the physico-chemical properties of the four pesticides and the physiological and morphological properties of the three microalgae.
CitationGuanzon Jr., N. G., & Nakahara, H. (2002). Growth and photosynthesis inhibition by agricultural pesticides in three freshwater microalgae.
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Conference paperIC Liao, JJ Guo & MS Su - In JR Arthur, CR Lavilla-Pitogo & RP Subasinghe (Eds.), Use of Chemicals in Aquaculture in Asia : Proceedings of the Meeting on the Use of Chemicals in Aquaculture in Asia 20-22 May 1996, Tigbauan, Iloilo, Philippines, 2000 - SEAFDEC Aquaculture DepartmentAquaculture in Taiwan has a history of more than three centuries. To satisfy consumer preferences, a wide variety of aquatic species, 71 in 1993, are being cultured in Taiwan. It is difficult to control diseases when many species are cultured and stocking densities are high. At present, it is important to manage the use and application of chemotherapeutants effectively. Many aquatic animal diseases fall under the category of potentially curable illnesses. These include diseases of bacterial, protozoan, fungal, and environmental etiologies. This paper summarizes the chemicals used in aquaculture, farm management practices, alternative disease prevention methods, national regulations, and the current research on chemical use for aquaculture in Taiwan.
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Use of Chemicals in Aquaculture in Asia : Proceedings of the Meeting on the Use of Chemicals in Aquaculture in Asia. JR Arthur, CR Lavilla-Pitogo & RP Subasinghe (Eds.) - 2000 - SEAFDEC Aquaculture DepartmentThe use of chemicals is common in various aquaculture systems, as it is in many agricultural practices. However, with growing worldwide awareness of the need for responsible practices in aquaculture, governments and aquaculturists are increasingly concerned with the effects of the use of chemicals in aquaculture, especially those which appear likely to be hazardous to man, cultured stock and/or the environment. The need to synthesize and disseminate information on the use and management of double prime aquachemicals double prime was recognized by the Fishery Resources Division of the Food and Agriculture Organization of the United Nations (FAO) and the Southeast Asian Fisheries Development Center (SEAFDEC) Aquaculture Department, who convened double prime The Expert Meeting on the Use of Chemicals in Aquaculture in Asia, double prime which was held 20-22 May 1996 at the SEAFDEC facilities in Tigbauan, Iloilo, the Philippines. Support was provided by FAO, SEAFDEC and the Canadian International Development Agency s (CIDA) ASEAN Fund. The World Health Organization (WHO) supported the participation of a human health expert. The meeting was attended by 27 participants and more than 70 observers from the public and private sectors of 20 countries. Among the attendees were representatives from the Network of Aquaculture Centres in Asia-Pacific (NACA), the Fish Health Section of the Asian Fisheries Society (FHS/AFS), the Japan International Research Center for Agricultural Sciences (JIRCAS), the GESAMP Working Group on Environmental Impacts of Coastal Aquaculture, and the ICES Working Group on Environmental Interactions of Mariculture. The results of this expert workshop are presented in this volume. They include the texts of presentations on a wide range of topics (thematic reviews) related to the use of chemicals in aquaculture, with emphasis on the Asian Region, as well as country overview papers summarizing the use of aquachemicals in Asian countries. The contributions of the selected participants during the meeting are contained in this volume.
Book chapterET Taberna - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of AgricultureThe contribution of shrimp farm effluents to the pollution load in Imbang River, Negros Occidental was measured during the period May 1993 to February 1995. Shrimp pond effluents were characterized and the pollution load estimated. The pond effluents had low average nitrite (0.0025 ppm) and nitrate (0.06 ppm) and optimum (for shrimp culture) pH 7.9, phosphate 0.15 ppm, dissolved oxygen 5.20 ppm, and salinity 23.3 ppt. Ammonia was 0.13 ppm on average in most farms, above the safe level for shrimp, and total suspended solids was 23 ppm, about 2.5x the allowed limit for effluents. Biochemical oxygen demand (20 ppm) and settleable solids (0.15 ppm) were still with acceptable limits. Residues of organochlorine pesticides were present at very low concentrations, well below the safe levels for aquatic life. Most of the pollution load came from the regular water exchanges over the 4-month crop cycle, at least every two weeks in low-density farms and more frequently in the high-density farms. The total draining of pond water at harvest contributed a minor load. Total solids from shrimp farms contributed a huge load, about 181,325 mt/yr. Total suspended solids contributed 1,285 mt/yr and settleable solids <1 mt/yr. The total BOD load was 154,367 kg/yr. The phosphate load was about 1,080 kg/yr, and the total nitrogen load was 1,225 kg/yr. The effects of effluent release from farms were localized. Upstream water quality and other uses of the river were not affected. Since most of the shrimp farms were located 1.5–2 km from the sea, the release of effluents during water exchange and at harvest did not adversely affect water quality downstream of these farms. Where such draining increased the levels of ammonia, phosphate, and total suspended solids in the river, the effect was significant only within 250 m from the release point, and the pollutants were dissipated about 550–800 m downstream The other water quality variables were at low levels in the pond effluents and did not affect the river water during draining. Often the concentrations of pollutants in the river were higher before than during draining of pond effluents. Stations upstream of the release sites of pond effluents often had high pollutant concentrations from other upstream sources.