At the beginning of early 1990s the Food and Agriculture Organisation (FAO), the Organisation for Economic Cooperation and
Development (OECD) and the European Union (EU) Commission effectively focused on multifunctionality, while in Hungary this
term has only been highlighted in the last few years. As a consequence of the changes in Hungary in the last 15 years pond
fish farms have had to explore their potential to find out how they can diversify their activities in order to be able to
produce various fish products and to provide services for which there is demand from the market and the society. The application
of the multifunctional approach has proved to be a realistic option for many fish farms for their survival and sustainable
development. This paper demonstrates some examples of multifunctional fish farms, which clearly shows the business opportunities
lying in the diversification of farm activities. 相似文献
Drop-fill water management schemes for aquacultural ponds reduce both groundwater use and effluent release. A drop-fill scheme assumes that pond water level will be allowed to decrease to the “drop” depth before makeup water is used to return it to the “fill” depth, which is typically some fraction (e.g., 1/2) of the drop depth. This paper compares predicted performance of drop-fill schemes at five sites in the Southeast U.S. (Thompsons, TX, Stuttgart, AR, Stoneville, MS, Clemson, SC, and Fairhope, AL). The locations were chosen to assess the effect of the east–west precipitation gradient and the south–north change from maritime to continental characteristics on the drop-fill approach in this region.
Performance of the drop-fill schemes was based on calculated daily water balances for ponds using 40-year (1961–2000) precipitation (P) and evaporation (E) records at the sites. Pond evaporation is assumed to be 0.8 × pan evaporation. Since performance differences based on regional P minus E (P−E) records was the subject of this work, ponds were assumed identical in other respects (i.e., all ponds were assumed to be levee-type and to have zero infiltration).
Simulated drop-fill schemes tested included (in cm): 0/0, 5/2.5, 10/5, 15/7.5, 20/10, 25/12.5, 30/15, 45/22.5, 60/30, 90/45, and 120/60. Each scheme was simulated using daily time steps for 40 years at each site. Results suggested that rigorous adherence to even a modest drop-fill scheme results in substantial reductions in both groundwater use and effluent release. It also appears that P−E conditions at all sites allow implementation of more aggressive drop-fill schemes in properly designed ponds that will require no supplemental groundwater for most years. This was also true with respect to effluent release at three of five sites. At two sites, precipitation was sufficiently large that zero effluent years were either not predicted (Fairhope) or relatively uncommon (Clemson) for any drop-fill scheme. 相似文献
The aim of the present study was to investigate concentrations of total mercury (THg) and methylmercury (MeHG) in the common
carp from Czech ponds of Rožmberk, Spolsky, Nezmar, and Velky Bědny. Seven common carps (Cyprinuscaprio) from each of the ponds were caught. Muscle tissue, the liver, and the soft and hard roe were used for the tests. Total mercury
and methylmercury were found in all the muscle tissue samples examined. Detection limits for total mercury and methylmercury
determination methods were 0.001 mg kg–1 and 0.013 mg kg−1 respectively. Methylmercury levels in the liver and gonads were below the method’s limits of detection. THg and MeHg concentrations
in muscle tissues were 0.018–0.063 mg kg–1 w.w. and 0.019–0.063 mg kg–1 w.w. respectively. MeHg made up 90–100% of THg in muscle tissues. Total mercury and methylmercury concentrations were significantly
(P < 0.05) higher in fish from the Spolsky pond than from the Nezmar pond. MeHg/THg ratios were significantly (P < 0.05) higher in fish from the Rožmberk, Spolsky and Nezmar ponds compared with fish from the Velky Bědny pond. 相似文献
