Open-air treatment of wastewater from land-based marine fish farms in extensive and intensive systems: Current technology and future perspectives

Marine land-based fish farms located in coastal wetlands (salt-pond zones, lagoon banks, etc.), whether extensive or intensive, send farm effluents directly to the sea or after short periods of stocking in retention reservoirs. The aims of our investigation have been to compare the efficiency of current and potential water treatment procedures in open-air. Wastewater retention ponds in commercial farms (Atlantic coasts of France) are efficient in removing up to 1 metric ton of particulate material (dry weight) per hectare and per day (faeces and unconsumed feed), but are inefficient in reducing dissolved wastes, both organic (urea, amino acids, protein) and inorganic (total ammonia nitrogen, phosphates). Forthcoming outdoor technology to treat these forms of waste were examined by trials at different sites: treatment by foam fractionation in extensive systems (Italian fish pond culture), treatment by microalgae production (Skeletonema costatum) and oyster filtration (Crassostrea gigas) in intensive systems (sea bass farm, Dicentrarchus labrax). It can be concluded that foam fractionation coupled with aeration and water circulation is a good way to treat and recirculate wastewaters in extensive systems, but that a multiple treatment combining a retention pond, foam fractionation and microalgae-bivalve filtration, is the best solution to treat all these forms of wastes from intensive systems.     

巨藻潜筏式养殖技术的研究

根据巨藻生长特点及大规模养殖生产需要而进行了潜筏式平差和潜筏式垂养比较;不同养殖密度与产量的关系;不同分苗时间对产量的影响及不同流速下的内外海区对巨藻生长的影响等多项研究。     

Present Status of Research and Production of Japanese Flounder,Paralichthys olivaceus,in Japan

ABSTRACT

Aquaculture of Japanese flounder, Paralichthys olivaceus, started in the middle 1970s in Japan, and the commercial production became extensive in the early 1980s, with development of seedling production and farming techniques. Annual production in 1996 was 7,692 metric tons, ranked fourth among marine cultured finfish after yellow-tail, red sea bream, and coho salmon. Marine finfish aquaculture in Japan is mostly conducted in floating net cages; however, land-based culture tanks are the prevalent culture system for Japanese flounder. The tanks are circular, square, or octagonal and constructed of various materials: concrete, plastic and/or a combination of the two. Culture tanks are generally inside or covered with shade cloths. Sand-filtered sea water is continually supplied to each tank, with 12 to 24 exchanges daily. Three-gram fish are stocked in the culture tank and raised for 1 to 2 years until they grow to 500-1,000 g. Survival ranges from 60 to 80%. Sardines and sand lance, fresh or frozen, are mainly fed; however, use of moist or dry pellets are increasing recently because of the decline in catch of these fishes. Fingerlings are obtained from commercial hatcheries virtually year-round. The fish utilize almost no dietary carbohydrate as an energy source, and an increase of lipid in the diet did not improve the growth, although it did seem to produce a slight increase in protein efficiency ratio. Therefore, diet for Japanese flounder should contain high percentages of protein (fish meal). Finding alternative protein sources for fish meal in the diet has been researched, and the potential of defatted soybean, corn gluten, feather, meat, and meat bone meals have been examined. The optimum temperature for the growth is 20-25°C. Salinity range of 4.4 to 34.0 ppt did not affect the growth of Japanese flounder at 8 g initial body weight.     

Wetland monitoring: aquatic plant changes in two Corsican coastal lagoons (Western Mediterranean Sea)

• 1. A monitoring system was developed in two Corsican coastal lagoons (Biguglia and Urbino; Corsica, Western Mediterranean).
• 2. Three species of seagrass (Nanozostera noltii, Ruppia cirrhosa and Cymodocea nodosa) were monitored by (i) measuring spatio‐temporal changes in the seagrasses, using fixed structures, (ii) investigating temporal changes in the biological parameters of the seagrasses, and (iii) mapping their distribution by processing aerial images of both lagoons.
• 3. These investigations showed that, while the two lagoons exhibit, a priori, a certain structural homogeneity (ecosystems based on aquatic plants), they function in different ways that are specifically linked to environmental conditions.
• 4. At present, the estimated net production varies from 86 to 469 g C m^?2 yr^?1 at Biguglia and 190 to 1301 g C m^?2 yr^?1 at Urbino. These values confirm the richness of these two lagoons, and the interest of using seagrass, by means of regular monitoring, for the conservation and management of coastal lagoons.

Copyright © 2006 John Wiley & Sons, Ltd.     

Comparative Study on Precipitation Techniques for Protease Isolation and Purification from Labeo rohita Viscera

Precipitation techniques play a vital role in the industrial extraction of enzymes. The present study aimed to extract the proteases from the viscera of Labeo rohita (commonly called Rohu) and to compare the precipitation techniques for the isolation and purification of the enzyme. The enzyme is usually discarded as tons of waste during processing. Hence, a trial has been carried out to isolate the protease enzymes from viscera of the freshwater fish Labeo rohita. The proteases were precipitated with ammonium sulfate, ethanol, and acetone. Acetone precipitation was found to be the best option for the recovery of enzymes (54%) from the viscera of Rohu, and two caseinolytic protease bands were shown in the zymogram. The precipitates with highest proteolytic activity were further subjected to dialysis, and their molecular weight was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).     

On the ecology of brackish water lagoons in Great Britain

1. Recent data on habitat characteristics and the animal and plant communities from 166 brackish lagoons in Great Britain have been analysed to interpret their community stucture and the environmental features important to maintaining the diversity of specialist lagoonal species. 2. Lagoons supporting a diverse community of specialist species of restricted distribution are considered to be the most valuable in conservation terms. 3. Lagoons are concentrated in the south and east of the country, are predominantly shallow with fine sand and mud sediments and cover a range of sea-inlet types, areas and salinities (from zero to hyperhaline). 4. The environmental characteristics of lagoons show more variability than those of ambient sea-or estuarine water. 5. Six suites of species are identified: freshwater species, stenohaline marine lagoonal specialists, euryhaline lagoonal specialists, estuarine species tolerant of lagoons, estuarine species incidental in lagoons and underrecorded species. 6. The lagoons are categorized as freshwater sites and groups of saline sites of a range of conservation value in terms of their community, from high value sites dominated by stenohaline specialist species to sites supporting no specialist lagoonal community. 7. The higher value sites are bar-built or sluiced lagoons with a channel inlet, with salinities close to 35%₀, a heterogeneous sediment, predominantly shallow and with larger area if narrow. Spatial density of lagoons may be important in recruitment of stenohaline specialist species, and frequent exchange of a proportion of the lagoon water with adjacent estuary or sea-water may be important in maintaining requisite salinity. 8. Aspects worthy of further study are identified.     

Sludge Production and Management for Recirculating Aquacultural Systems

Waste discharge from recirculating aquacultural systems is typically in the form of sludge composed of partially stabilized excreta, uneaten food particles, and bacterial growth. The amount of solids produced can be estimated using an equation presented in this paper. In a typical recirculating system, total suspended solids (TSS) is the major pollutant of the sludge produced. The production of TSS ranges from 10 to 30% of the feeding rate on a dry weight basis. The ratio of 5-d biochemical oxygen demand to total suspended solids (BOD_S/TSS) of the sludge ranges from 0.10 to 0.2, the total Kjeldahl nitrogen (TKN) content of the TSS ranges from 4 to 6%, and total phosphorus ranges from 0.2 to 2%.
The nature of the waste and the economics of the treatment processes dictate the disposal of aquacultural sludge. Effective clarification of aquacultural waste is critical in reducing sludge volume. Using lagoons for stabilization and storage is the most practical option. While direct disposal by land application seems feasible for rural areas with dry climates, additional stabilization/storage in a lagoon with eventual disposal through land application seems most feasible for a variety of conditions. The effluent produced from the sludge treatment processes can be used for irrigation or for direct discharge after further polishing (treatment).     

Production and application of on‐grown Artemia in freshwater ornamental fish farm

Abstract

This paper describes a pilot culture system for the production of on‐grown Artemia in freshwater ornamental fish farms. The system had 21 culture units, each consisting essentially of three components: an oval‐shaped raceway, an air‐water lift system and two waste collectors. Using artificial seawater at 20 ppt for culture and at a mean production rate of 3 kg/m³ of water in a 12‐day cycle, the system had a production capacity of 8 metric tons of on‐grown Artemia a year. Biochemical analyses were preformed to evaluate the nutritional value of the on‐grown Artemia against three conventional live feeds, viz. live Artemia nauplii, live Moina and frozen bloodworms. Cost‐benefit analysis showed that with a capital investment of US$ 82,000 and an annual cost of production of US$ 81,000, the system achieved a high internal rate of return of 88% over a 10‐year period and a short payback period of 1.23 years. The availability of on‐grown Artemia would not only offer farmers and exporters a better alternative live food organism for feeding to their fish, but more importantly the possibility of enhancing the fish performance and quality through bioencapsulation.     

Options to reuse sludge from striped catfish (Pangasianodon hypophthalmus,Sauvage, 1878) ponds and recirculating systems

This paper compares the quantity and quality of solid waste obtained from traditional ponds and recirculating aquaculture systems (RAS) for striped catfish and evaluates methane and compost production from these wastes. Striped catfish sludge was collected from four commercial ponds along the Mekong river and from three indoor RAS. The amount of sludge dry matter produced per kilogram of fish in ponds was 6 times higher than that in RAS. However, the concentration of nutrients in solid waste from RAS was much higher, with better compost quality and higher methane yield than that of sludge from ponds. Out of the collected 381 L biogas, the methane yield of striped catfish’s solid waste in RAS systems was 201 L per kg chemical oxygen demand (COD). In ponds, the collected 267 L biogas yielded 125 L CH₄ per kg COD. The higher methane production from RAS sludge concurred with higher digestibility of COD: 58% for RAS versus 38% for ponds. The quality and quantity of methane from striped catfish sludge were lower than that for other animal manures, and the resulting electricity yield was low. Considering the higher nutrient concentration in RAS-sludge, we recommend the combination RAS and composting in reusing sludge, which is presently the best option for a more sustainable and cleaner striped catfish production system.     

Predation on Pacific herring (Clupea pallasi) spawn by birds in Prince William Sound,Alaska

We examined bird diets in areas with Pacific herring (Clupea pallasi) spawn at northern Montague Island in Prince William Sound, Alaska. Diets of the five most abundant bird species consisted primarily of herring spawn. Using a bioenergetics model, we estimated that in spring 1994 the five‐bird species ate 857.1 metric tons (mt), representing 31% of the estimated spawn deposition. The two most numerous consumers, glaucous‐winged gull (Larus glaucescens) and mew gull (Larus canus) consumed 26% and 3%, respectively, of the estimated spawn deposition. Surf scoters (Melanitta perspicillata), surfbirds (Aphriza virgata), and black turnstone (Arenaria melanocephala) together consumed 2% of the spawn deposition. In years with low spawn biomass, such as 1994, the number of herring larvae produced could be significantly affected by normal rates of avian predation. The high consumption by gulls, shorebirds, and surf scoters underscores the importance of herring spawn in the annual cycle of these species and requires further investigation.     

Decomposition processes in coastal lagoons and their implications for the assessment of ecological health

相似文献   

Economics of Sustainable Intensification of Aquaculture: Evidence from Shrimp Farms in Vietnam and Thailand

There is growing interest in sustainable intensification of aquaculture production. Yet little economic analysis has been done on farm‐level effects of the economic sustainability of production intensification. Data from 83 shrimp farms (43 in Vietnam and 40 in Thailand) were used to identify (through principal component and cluster analyses) 13 clusters of management practices that reflected various scales of production intensity that ranged from 0–1999 kg/ha/crop to 10,000 kg/ha/crop and above, for both Penaeus monodon and Litopenaeus vannamei in Vietnam and Thailand. The clusters identified reflected sets of management practices that resulted in differing yields despite similarities in stocking densities among some clusters. The enterprise budget analysis developed showed that the more intensively managed clusters outperformed the less intensively managed clusters in economic terms. More intensively managed farm clusters had lower costs per metric ton of shrimp produced and were more profitable. The greater yields of shrimp produced per hectare of land and water resources in more intensively managed shrimp farms spread annual fixed costs across a greater volume of shrimp produced and reduced the cost per metric ton of shrimp. Costs per metric ton of shrimp produced decreased from the lowest to the highest intensity level (from US$10,245 at lowest intensity to US$3484 at highest for P. monodon and from US$24,301 to US$5387 for L. vannamei in Vietnam and from US$8184 at the lowest intensity level to US$3817 at the highest intensity level per metric ton for L. vannamei in Thailand). Costs of pond amendments used in shrimp production were particularly high in Vietnam and largely unwarranted, whereas fixed costs associated with the value of land, production facilities, equipment, and labor were sufficiently high in Thailand so that net returns were negative in the long run. Nevertheless, economic losses in Thailand were less at greater levels of intensification. The study demonstrated a clear value proposition for shrimp farmers to use natural resources (such as land) and other inputs in an efficient manner and supports findings from corresponding research on farm‐level natural resource use efficiency. Additional research that incorporates economic analysis into on‐farm studies of sustainable intensification of aquaculture is needed to provide ongoing guidance related to sustainable management practices for aquaculture.     

Fishing for feed in China: Facts,impacts and implications

China is the world's largest capture fisheries and aquaculture producer. Over recent decades, China's domestic marine catch composition has changed markedly, from large volumes of a few high‐valued food species to multiple, small, low‐valued, species, a significant proportion of which is primarily used as animal, especially fish, feed. Despite the growing volume and economic importance of the feed catches, their species composition, catch volumes and socio‐environmental impacts are all poorly understood. Based on a nationwide survey of >800 fishing vessels, and the identification and measurement of >12,000 fish and invertebrate individuals, the present study provides an overview of the feed component of China's domestic marine catch, by volumes, species and sizes, and found it to be substantial and biologically unsustainable. Half of the trawler catch (3 million metric tons, mmt), or 35% of the total catch (4.6 mmt) in China's exclusive economic zone, are now comprised of low‐valued “feed‐grade fish”. The present study identified 218 fish species, 50 crustaceans and five cephalopods, and of these, 102 fish species were food species with 89% individuals in their juvenile size ranges. Feed‐grade fish were mainly used as aquaculture feed directly, or indirectly, through the feed industry after reduction to fishmeal and fish oil. The unparalleled scale and poor fisheries resource condition of China's domestic marine fisheries, in parallel with severe overfishing of juveniles, creates a demand for fundamental changes to fishery management practices, including a significant reduction of fishing effort to ensure productivity and ecosystem resilience.     

青海湖裸鲤种群数量变动的初步分析

青海湖裸鲤是青海湖唯一的捕捞对象。开发后的种群数量变动主要根据1975-1977年该湖渔获物资料及过去研究的裸鲤生物学特性。计算了该种群的若干特征值，应用BevertonHolt数学模式计算不同捕捞努力量或用不同网目的拖网对裸鲤种群在一生中总个体数、总生物量，和对裸鲤种群一生中能捕捞的总个体数及总渔获重量的影响，以及裸鲤的最大持续产量和现有种群数量。评价了裸鲤资源利用现状，提出有关生产的一些初步意见。     

Development of techniques for the cultivation of Lessonia trabeculata Villouta et Santelices (Phaeophyceae: Laminariales) in Chile

Large quantities of brown algae have traditionally been exported from Chile as a raw material, of which Lessonia spp. has amounted to over 130 000 tons annually since 1995. To the export demand has recently been added the new demand for high‐quality Lessonia spp. as a foodstuff for the expanding abalone culture industry in Chile. The present study is based on efforts to produce significant quantities of Lessonia trabeculata in long‐line culture as food for tank‐cultured Haliotis rufescens Swainson and Haliotis discus‐hannae Ino, which accept it as an excellent source of nutrition. Small sporophytes of L. trabeculata were propagated in the laboratory from reproductive blades harvested by diving near Coquimbo (30°S). The best culture substrate was polyvinyl chloride (PVC) in small pieces, inserted into the nylon cord for final culturing. Enrichment of sea water with agricultural‐grade fertilizer produced no differences in growth and development of the Lessonia compared with results obtained using Provasoli medium. Sporophytes 1–2 cm in length cultured on 12‐mm cord were transferred to outdoor tanks with circulating sea water and strong aeration where they were outgrown to 15–20 cm length; at this size, they were transferred to a 50‐m long line in the ocean. In a 1‐year period, individual plants reached up to 1.7 kg in mass, with average values per cord of about 9 kg. Total production from the long line was about 500 kg fresh weight of the alga. In comparative testing, H. discus hannae grew as well on the cultured algae as on naturally occurring L. trabeculata.     

Introduced northern pike consumption of salmonids in Southcentral Alaska

The impacts of introduced northern pike (Esox lucius) on salmonid populations have attracted much attention because salmonids are popular subsistence, sport and commercial fish. Concern over the predatory effects of introduced pike on salmonids is especially high in Southcentral Alaska, where pike were illegally introduced to the Susitna River basin in the 1950s. We used pike abundance, growth, and diet estimates and bioenergetics models to characterise the realised and potential consumptive impacts that introduced pike (age 2 and older) have on salmonids in Alexander Creek, a tributary to the Susitna River. We found that juvenile salmonids were the dominant prey item in pike diets and that pike could consume up to 1.10 metric tons (realised consumption) and 1.66 metric tons (potential consumption) of juvenile salmonids in a summer. Age 3–4 pike had the highest per capita consumption of juvenile salmonids, and age 2 and age 3–4 pike had the highest overall consumption of juvenile salmonid biomass. Using historical data on Chinook salmon and pike potential consumption of juvenile salmonids, we found that pike consumption of juvenile salmonids may lead to collapsed salmon stocks in Alexander Creek. Taken together, our results indicate that pike consume a substantial biomass of juvenile salmonids in Alexander Creek and that coexistence of pike and salmon is unlikely without management actions to reduce or eliminate introduced pike.     

Persistence of fish populations in the upper Paraná River: effects of water regulation by dams

Abstract –  River–floodplain systems present intense temporal variations in physical, chemical and biological factors. These variations are closely related to alterations in water levels, which have been attributed to the flood pulse. As several species are strictly related to the flood pulse to fulfil their life cycle, the pulse may be seen as a dispersal mechanism of species onto a floodplain. In this study, we determine how dam construction influenced the persistence of Prochilodus lineatus population, a large migratory fish species from the upper Paraná River floodplain. Data used were collected in two distinct periods, from April 1992 to March 1993 and from January 1999 to December 2001. Fish were collected using seining nets in six (monthly in the first period) and seven (quarterly in the second period) isolated lagoons. The fraction of occupied lagoons was high in the first period (higher than 0.65), when flood was intense. However, in the second period, when the flood pulse did not happen or was short, the fraction of occupied lagoons sharply decreased over time (from 0.85 to 0.22). For the first period, no model fitted to data, but for the second period, a negative linear model (named drought-dependent model) presented good fit ( r ² = 0.97). Therefore, it is possible to infer that long and intense flood pulses are important to maintain the persistence of P. lineatus populations in the floodplain. The artificial control of water levels prompted by dams disrupts this dynamic, reducing persistence to critical levels.     

Apparent digestibility coefficients of selected feed ingredients for juvenile snakehead,Ophiocephalus argus

Apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, gross energy, phosphorus and amino acids in Peruvian fish meal, poultry by‐product meal, meat and bone meal, spray‐dried blood meal, hydrolysed feather meal, corn gluten meal, soybean meal, peanut meal, cottonseed meal and rapeseed meal were determined for juvenile snakehead (Ophiocephalus argus) with initial mean body weight of 78.1 g. A reference diet and test diets that consisted of a 70 : 30 mixture of the reference diet to test ingredient were used with 5 g kg^?1 Cr₂O₃ as an external indicator. Fish meal, poultry by‐product meal and corn gluten meal had higher ADCs of dry matter, crude protein, and gross energy among ingredients tested. Dry matter ADCs ranged 61.9–81.5% for animal ingredients and corn gluten meal and ranged 52.2–68.0% for soybean meal, peanut meal, cottonseed meal and rapeseed meal. Energy ADCs of ingredients followed similar trends to differences in dry matter digestibility. Protein ADCs of animal and plant ingredients ranged 73.6–92.8% and 75.3–85.6%, respectively. Amino acid ADCs generally reflected protein digestibility. Lipid ADCs were relatively high for the ingredients tested. Phosphorus ADCs of animal and plant ingredients ranged 39.5–65.2% and 38.7–57.1%, respectively.     

Water quality,waste production,and off-flavor characterization in a depuration system stocked with market-size Atlantic salmon Salmo salar

Land-based Atlantic salmon, Salmo salar, grow-out facilities utilize depuration to remediate off-flavor. Water used in this process is either discharged or repurposed as supply water in recirculating aquaculture systems (RAS). Both approaches require an understanding of water quality and waste production for water treatment decisions and compliance with pollution discharge standards; however, these data were lacking. Therefore, a study was carried out to characterize these parameters. To begin, 311 salmon (5–6 kg) originally cultured in freshwater RAS were stocked at 100 kg/m³ in an 18 m³ depuration tank. Feed was withheld 1 day before transfer and throughout the 7-day study period. Hours after stocking, total suspended solids (TSS), total phosphorus (TP), and total ammonia nitrogen (TAN) levels spiked, and concentrations declined thereafter. Delta TSS and TP were negligible by the end of the trial; however, TAN plateaued, indicating that salmon began to catabolize somatic tissue in the absence of feeding. Geosmin and 2-methylisoboreol levels in water and fish were low throughout the study. This research indicates that residual waste production occurs while depurating Atlantic salmon. Procedural refinements and recommendations were gleaned including locality for introducing depuration system water within RAS and extension of the feed withholding period before depuration.     

Aquatic Coleoptera and Hemiptera assemblages in three coastal lagoons of the NW Iberian Peninsula: assessment of conservation value and response to environmental factors

• 1. The objectives of the present study were to describe and analyse the composition and structure of aquatic Coleoptera and Hemiptera assemblages in three coastal lagoons of north‐western Spain during a one year cycle, in order to evaluate their relative adequacy to provide information about the conservation value of lagoonal habitats and sites. The lagoons are designated as Special Areas of Conservation (SAC) under the European Union Habitats Directive and two of them are also protected by the Ramsar Agreement. Several abiotic variables, including salinity, were recorded at the time of sampling.
• 2. In total, 67 species (52 Coleoptera and 15 Hemiptera) and 6568 adult individuals (2664 Coleoptera and 3904 Hemiptera) were collected. In all pair‐wise comparisons Kendall's coefficients of concordance between lagoons were higher for Hemiptera than for Coleoptera, indicating that Hemiptera assemblages were more similar across sites.
• 3. Most species recorded had a wide Palearctic distribution and only three species of water beetles could be considered endemic to Iberia: Hydroporus vagepictus, Hydroporus vespertinus and Hydrochus angusi. Similarly, the species collected had a widespread distribution in the Iberian Peninsula as the only species considered to be rare taxa at this scale were Hydrochus angusi and Cymbiodyta marginella among the Coleoptera and Sigara scotti and Notonecta glauca glauca among the Hemiptera.
• 4. The results do not support the idea of distinct aquatic insect assemblages for coastal lagoons in the Iberian Peninsula. Comparisons of the numbers of interior (non‐coastal) and coastal provinces of the Iberian Peninsula where the species had been recorded showed they had been recorded in a larger proportion of interior provinces.
• 5. Salinity seemed to reduce species richness in both groups while the results of a canonical correspondence analysis (CCA) showed that the majority of species responded negatively to salinity.
• 6. This study suggests that species richness and rarity of aquatic insect assemblages may underestimate the conservation value of lagoonal habitats because their net contribution to catchment biodiversity is likely to be low.

Copyright © 2007 John Wiley & Sons, Ltd.