Carbon Metabolism Transitions during the Development of Marine Macroalga Gracilaria verrucosa

The changes in the rate of photosynthetic and dark CO₂ assimilation and the activity of key enzymes of carboxylation were studied during the main developmental stages (shoots, juvenile plants, and mature plants) of red macroalga Gracilaria verrucosa (Huds.) Papenf. Changes in the direction of primary carbon metabolism were also investigated. It was estimated that the transition of metabolism related to the shift in the pathways of carboxylation did not occur during development of G. verrucosa. During all developmental stages, the level of dark CO₂ assimilation was by at least one order of magnitude lower than that of photosynthetic assimilation The predominant pathway of CO₂ assimilation was ribulosobisphosphate carboxylation. At the same time, the transition of metabolism related to the changes in the type of phosphoglyceric acid utilization was found. At the early developmental stages, a substantial part of phosphoglyceric acid was directed into the amino acid metabolism via the anaplerotic pathway of photosynthesis similar to that in higher plants.     

A preliminary study of the bioremediation potential of Codium fragile applied to seaweed integrated multi-trophic aquaculture (IMTA) during the summer

In integrated multi-trophic aquaculture (IMTA), seaweeds have the capacity to reduce the environmental impact of nitrogen-rich effluents in coastal ecosystems. To establish such bioremediation systems, selection of suitable seaweed species is important. The distribution and productivity of seaweeds vary seasonally based on water temperature and photoperiod. In Korea, candidate genera such as Pophyra, Laminaria, and Undaria grow from autumn to spring. In contrast, Codium grows well at relatively high water temperatures in summer. Thus, aquaculture systems potentially could capitalize on Codium’s capacity for rapid growth in the warm temperatures of late summer and early fall. In this study, we investigated ammonium uptake and removal efficiency by Codium fragile. In laboratory experiments, we grew C. fragile under various water temperatures (10, 15, 20, and 25°C), irradiances (dark, 10, and 100 μmol photons m⁻² s⁻¹), and initial ammonium concentrations (150 and 300 μM); in all cases, C. fragile exhausted the ammonium supply for 6 h. At 150 μM of , ammonium removal efficiency was greatest (99.5 ± 2.6%) when C. fragile was incubated at 20°C under 100 μmol photons m⁻² s⁻¹. At 300 μM of , removal efficiency was greatest (86.3 ± 2.1%) at 25°C under 100 μmol photons m⁻² s⁻¹. Ammonium removal efficiency was significantly greater at 20 and 25°C under irradiance of 100 μmol photons m⁻² s⁻¹ than under other conditions tested.     

An integrated fish–plankton aquaculture system in brackish water

Integrated Multi-Trophic Aquaculture takes advantage of the mutualism between some detritivorous fish and phytoplankton. The fish recycle nutrients by consuming live (and dead) algae and provide the inorganic carbon to fuel the growth of live algae. In the meanwhile, algae purify the water and generate the oxygen required by fishes. Such mechanism stabilizes the functioning of an artificially recycling ecosystem, as exemplified by combining the euryhaline tilapia Sarotherodon melanotheron heudelotii and the unicellular alga Chlorella sp. Feed addition in this ecosystem results in faster fish growth but also in an increase in phytoplankton biomass, which must be limited. In the prototype described here, the algal population control is exerted by herbivorous zooplankton growing in a separate pond connected in parallel to the fish–algae ecosystem. The zooplankton production is then consumed by tilapia, particularly by the fry and juveniles, when water is returned to the main circuit. Chlorella sp. and Brachionus plicatilis are two planktonic species that have spontaneously colonized the brackish water of the prototype, which was set-up in Senegal along the Atlantic Ocean shoreline. In our system, water was entirely recycled and only evaporation was compensated (1.5% volume/day). Sediment, which accumulated in the zooplankton pond, was the only trophic cul-de-sac. The system was temporarily destabilized following an accidental rotifer invasion in the main circuit. This caused Chlorella disappearance and replacement by opportunist algae, not consumed by Brachionus. Following the entire consumption of the Brachionus population by tilapias, Chlorella predominated again. Our artificial ecosystem combining S. m. heudelotii, Chlorella and B. plicatilis thus appeared to be resilient. This farming system was operated over one year with a fish productivity of 1.85 kg/m² per year during the cold season (January to April).     

南日岛鲍鱼养殖产业的发展与展望

福建省莆田市南日岛独特的地理位置和良好的环境资源为鲍鱼养殖提供了优越的条件。本文概述了近10年来南日岛鲍鱼养殖发展所取得的经验及存在的问题,从保护生态环境、产品质量、品牌和技术等方面评述了\"南日鲍\"养殖产业的发展,并提出通过研发新的养殖模式、拓展养殖区域、加强养殖海域管理、调整优化鲍鱼养殖产业结构、改进养殖技术、发展休闲渔业等一系列措施,进一步促进南日鲍养殖产业的可持续发展。     

Applications and needs of fish and shellfish cell culture for disease control in aquaculture

This review focuses on the application of cellculture and in vitro methods to addresssome of the key elements identified asstrategies for integrated health management inaquaculture, including the standardization andvalidation of diagnostic methods, thedevelopment of new safe therapeutants, and theimplementation of effective disease controlmethodologies. It is expected that anylong-term rise in seafood production willdepend on the future progress of aquaculture.However, the development of aquaculture faces anumber of problems, of which diseases –particularly the emergence of new pathogens –represent serious risks for the production ofaquatic animals, but also for the health offish farmers and of the consumers ofaquaculture products. The complex interactionsunderlying disease outbreak and progression maybe better studied using in vitro modelsthat use cell/tissue culture methods andexperimental systems, in which the interactionsbetween aggressors and the host can bedissected. Researchers have developed invitro assays for fish toxicological,pathological, and immunological studies, as thein vitro assays allow higher control ofthe conditions of the experiments. Thecombination of cell/tissue cultures and invitro assays reduces also the variability ofthe in vivo responses, which are due tothe unavoidable effects of stress and ofenvironmental influences, and to the disparategenetic backgrounds of farmed fish andshellfish species.