Effects of CO2-induced ocean environmental changes on marine life: implications for aquaculture.
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The world's oceans are becoming warmer and acidic. The atmospheric carbon dioxide concentration has increased from 280 ppm at pre-industrial revolution to above 380 ppm today. The 4th IPCC report predicts that it will range from 540 to nearly 1,000 ppm by the end of the century. The increased CO2 not only warms surface seawater, but also acidifies it (usually termed as ocean acidification) by diffusing across the ocean surface and forming carbonic acid. Our knowledge is still scarce as to how these ocean environmental changes will affect marine life. The early studies on the impact of ocean acidification focused on corals aiming to clarify effects of high-CO2 seawater on their calcification processes. However, more recent studies have revealed that in fact ocean acidification, either alone or coupled with warming, could have detrimental impacts on a variety of biological processes in different taxa. We have shown that early development of marine bivalves (oysters and mussels) could be severely disrupted under elevated CO2 conditions (ca. 2,000 ppm). When a marine shrimp was exposed to seawater equilibrated with air containing 1,000 ppm CO2 for 30 weeks, survival was only 55% as compared with 90% in the control. Gonad maturation of a sea urchin was delayed by one month under the same CO2 conditions at ambient temperature, but when accompanied with increased temperature of 2 degree C above ambient, gonad maturation was not only delayed but also significantly suppressed; the number of eggs in the ovary was reduced to only 20% of the control. It has been shown that tropical animals already live near their thermal tolerant maxima, and therefore even small increases of environmental temperature could reduce their environmental fitness. These recent findings bear significant implication in aquaculture and fisheries production, in particular, in tropical countries. This paper will summarize recent data on these topics and discuss possible adaptation measures.
Ishimatsu, A., & Kurihara, H. (2011). Effects of CO2-induced ocean environmental changes on marine life: implications for aquaculture. In B. O. Acosta, R. M. Coloso, E. G. T. de Jesus-Ayson, & J. D. Toledo (Eds.), Sustainable aquaculture development for food security in Southeast Asia towards 2020. Proceedings of the Regional Technical Consultation on Sustainable Aquaculture Development in Southeast Asia Towards 2020 (pp. 35-44). Tigbauan, Iloilo, Philippines: SEAFDEC Aquaculture Department. http://hdl.handle.net/10862/1821
PublisherAquaculture Department, Southeast Asian Fisheries Development Center
Abiotic factors; Acidification; Adaptations; Animal growth; Aquaculture; Calcification; Carbon dioxide; Climatic changes; Coral; Data processing; Eggs; Environmental changes; Environmental effects; Fisheries; Fitness; Global warming; Gonads; Larval development; Marine environment; Oceans; Ovaries; Survival; Temperature effects; Temperature tolerance; Water temperature; Carbonic acid; pH effects; Corals; Development; Echinoidea; Penaeidae; Eastern Pacific
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Changes in Na+, K+-ATPase activity and gill chloride cell morphology in the grouper Epinephelus coioides larvae and juveniles in response to salinity and temperature The activity of the enzyme Na+, K+-ATPase and morphological changes of gill chloride cells in grouper, Epinephelus coioides larvae and juveniles were determined 6–48 h after abrupt transfer from ambient rearing conditions (30–32 ppt, 26.5–30°C) to different salinity (8, 18, 32, 40 ppt) and temperature (25, 30°C) combinations. Na+, K+-ATPase activity in day 20 larvae did not change at salinities 8–32 ppt. Activity decreased significantly (P <0.01) after exposure to 40 ppt at 25–30°C, which was accompanied by an increase (P < 0.05) in density and fractional area of chloride cells. Enzyme activity in 40 ppt did not reach a stable level and larvae failed to recover from an osmotic imbalance that produced a low survival at 25°C and death of all larvae at 30°C. Enzyme activity and chloride cell morphology in day 40 groupers did not change in 8–40 ppt at 25°C and 8–32 ppt at 30°C. A significant decrease and a subsequent increase in Na+, K+-ATPase activity in 40 ppt at 30°C was associated with the increase in chloride cell density resulting in an increased fractional area but a decreased cell size. Enzyme activity and chloride cells of day 60 grouper were unaffected by abrupt transfer to test salinities and temperatures. These results demonstrate that grouper larvae and juveniles are efficient osmoregulators over a wide range of salinities. Salinity adaptation showed an ontogenetic shift as the larvae grew and reached the juvenile stage. This development of tolerance limits may reflect their response to actual conditions existing in the natural environment.
Conference paperM Sano, T Ito, J Kurita, K Yuasa, S Miwa & T Iida - In CR Lavilla-Pitogo & K Nagasawa (Eds.), Transboundary Fish Diseases in Southeast Asia: Occurence, Surveillance, Research and Training. Proceedings of … Diseases in Southeast Asia: Occurence, Surveillance, Research and Training, Manila, Philippines, 23-24 June 2004, 2004 - Aquaculture Department, Southeast Asian Fisheries Development CenterThe mortality rate among common carp for food reared in net pens in Lake Kasumigaura, the second largest lake in Japan, in Ibaraki Prefecture, increased from early October 2003 and koi herpesvirus (KHV) was detected in the affected fish by the National Research Institute of Aquaculture (NRIA) in late October using PCR methods of Gilad et al. (2002) and Gray et al. (2002). The Ministry of Agriculture, Forestry and Fisheries of Japan officially announced the first occurrence of KHV disease in Japan. In late October 2003, the water temperature of Lake Kasumigaura was 16-180C and the fish losses were severe, particularly in market-sized carp. The apparent symptoms of affected fish were presence of mucus-like substance on the body surface, sunken eyes, and pale and necrotic gills, which were similar to those reported by Hedrick et al. (2000). Approximately 1,200 metric tons of common carp cultured in the lake were lost by mid-November. Prior to this, however, infected carp cultured in Lake Kasumigaura had already been transferred to farms, wholesalers, restaurants and game fishing facilities. Consequently, the infection spread to other areas in Japan. Independent of the outbreak in Lake Kasumigaura, a massive carp loss of over 10 thousand fish, the cause of which was initially diagnosed as columnaris disease, occurred in some rivers and a lake in Okayama Prefecture from late May to mid-July 2003. In November, the NRIA detected KHV DNA by PCR from samples of the diseased fish stored in a freezer. This demonstrated that KHV was present in Japan before late May 2003. By the end of 2003, KHV was detected in carp from 23 out of 47 prefectures in Japan. No occurrence of the disease was observed during the winter period. However, as the water temperature increased in spring of 2004, KHV reappeared in the area where the disease had been previously recorded, and also in new places. In many of the facilities that experienced KHV outbreak in 2003, the disease was not observed by June 2004 because all carp had been removed together with other fish species and the facilities were disinfected thoroughly after the outbreaks. From January to the end of May 2004, KHV infections were reported in 24 of 47 prefectures in Japan.
Thyroxine injection of female rabbitfish (Siganus guttatus) broodstock: changes in thyroid hormone levels in plasma, eggs, and yolk-sac larvae, and its effect on larval growth and survival The thyroid hormone levels in female rabbitfish, Siganus guttatus, plasma, eggs, and yolk-sac larvae were measured before and after thyroxine (T4) injection in female spawners at doses of 1, 10, and 100 μg T4/g body weight (BW) fish. T4 and triiodothyronine (T3) levels in maternal plasma, eggs, and yolk-sac larvae were elevated following T4 administration. Apparently, there is conversion of T4 into T3 in the broodfish which suggests the presence of the enzyme, 5′-monodeiodinase, in rabbitfish. T4 and T3 in maternal circulation were easily transferred into the oocytes and subsequently into the larvae. Larvae from spawners treated with 10 and 100 μg T4/g BW tended to be longer and showed sornewhat better survival compared to the control and those injected with 1 μg T4/g BW 7 days after hatching. These findings suggest that thyroid hormones may play an important role during early larval development of rabbitfish.