Developing Porphyra/salmon integrated aquaculture for bioremediation and diversification of the aquaculture industry

For rapid growth and appropriate pigmentation,Porphyra requires the constant availability of nutrients, especially in summer when temperate waters are generally nutrient depleted. Cultivation near salmon cages allows the alleviation of this seasonal depletion by using the significant loading of fishf arms, which is then valued (wastes become fertilisers) and managed (competition for nutrients between desirable algal crops and problem species associated with severe disturbances). Porphyra,being an extremely efficient nutrient pump, is an excellent candidate for integrated aquaculture for bioremediation and economic diversification. Frequent harvesting provides for constant removal of significant quantities of nutrients from coastal waters, and for production of seaweeds of commercial value. The production of P. yezoensis being limited in the Gulf of Maine, an assessment of the potential of seven native north-west Atlantic Porphyra species is presently in progress. To enable the production of conchospores for net seeding, the phenology of these species and the conditions for their vegetative conchocelis exponential growth, conchosporangium induction, and conchospore maturation were determined. The development of integrated aquaculture systems is a positive initiative for optimising the efficiency of aquaculture operations, while maintaining the health of coastal waters. This revised version was published online in August 2006 with corrections to the Cover Date.     

87 Algal bioremediation of eutrophic effluents in small scale integrated aquaculture systems

Protoplast regeneration from extruded cytoplasm of the multi-cellular marine green alga Microdictyon umbilicatum (Velley) Zanardini (Cladophorales, Anadyomenaceae) was investigated. The early process of protoplast formation is comprised of two steps: agglutination of cell organelles into protoplasmic masses followed by generation of a temporary enclosing envelope around them. Agglutination of cell organelles was mediated by a lectin-carbohydrate complementary system. Three sugars, D-galactosamine, D-glucosamine, and a-D-mannose, inhibited the agglutination process, and three complementary lectins for the above sugars, peanut agglutinin, Ricinus communis agglutinin and concanavalin A, bound to the surfaces of chloroplasts. Agglutination assay using human erythrocytes showed the presence of lectins specific for the above sugars in the algal vacuolar sap. The lectin has been purified by the use of D-mannose agarose affinity column. Its Molecular weight was shown to be 36,000 dalton by SDS-PAGE gel electrophoresis. When the basic regeneration process was accomplished, the cells chose one of two developmental strategies; about 70% of one-celled protoplasts transformed into reproductive cells within two weeks after wounding, while others began cell division and grew into typical Microdictyon plants. Quadriflagellate swarmers were liberated from the reproductive cells, and they germinated into mature plants     

Microbial mats for multiple applications in aquaculture and bioremediation

Microbial mats occur in nature as stratified communities of cyanobacteria and bacteria, but they can be cultured on large-scale and manipulated for a variety of functions. They are complex systems, but require few external inputs. The functional uses of mats broadly cover the areas of aquaculture and bioremediation. Preliminary research also points to promising uses in agriculture and energy production. Regarding aquaculture, mats were shown to produce protein, via nitrogen fixation, and were capable of supplying nutrition to tilapia (Oreochromis niloticus). Current research is examining the role of mats in the nitrification of nutrient-enriched effluents from aquaculture. Most research has addressed bioremediation, within which two majors categories of contaminants were examined: metals and radionuclides, and organic contaminants. Mats sequester or precipitate metals/radionuclides by surface absorption or by conditioning the surrounding chemical environment, thus bioconcentrating the metal/radionuclide in a small volume. Organic contaminants are degraded and may be completely mineralized. For agriculture mats hold promise as a soil amendment and nitrogen fertilizer. The use of mats in biohydrogen production has been verified, but is in a preliminary phase of development. We propose a comprehensive closed system based on microbial mats for aquaculture and waste management.     

The marine sponge Chondrilla nucula Schmidt, 1862 as an elective candidate for bioremediation in integrated aquaculture

The use of sponges for marine bioremediation in a farming scenario has been investigated focusing on Chondrilla nucula. We report experiments examining clearance and retention rates of the bacterium Escherichia coli. Despite low values expressed for clearance tests, C. nucula exhibited a marked ability to retain high quantities of bacteria. One square meter patch of this sponge can filter up to 14 l/h of sea water retaining up to 7 x 10(10) bacterial cells/h. This suggests that C. nucula is a suitable species for marine environmental bioremediation.     

Efficient bioremediation of total organic carbon (TOC) in integrated aquaculture system by marine sponge Hymeniacidon perleve

The aim of this study is to investigate the potential of using marine sponge Hymeniacidon perleve to remove total organic carbon (TOC) in integrated aquaculture ecosystems. In sterilized natural seawater (SNSW) with different concentrations of TOC, H. perleve removed approximately 44-61% TOC during 24 h, with retention rates of ca. 0.19-1.06 mg/h .g-fresh sponge, however no particulate selectivity was observed. The highest initial TOC concentration, in which about 2.7 g fresh sponges could remove TOC effectively in 0.5-L SNSW, is 214.3-256.9 mg/L. The highest capacity of TOC removal and clearance rate (CR) by H. perleve is ca. 25.50 mg-TOC/g-fresh sponge and 7.64 mL/h . g-fresh sponge within 24 h, respectively. Until reaching the highest TOC removal capacity, the TOC removal capacity and clearance rate of H. perleve increased with initial TOC concentration, and dropped dramatically thereafter. After reaching the highest removal capacity, H. perleve could only remove relatively lower TOC concentration in seawater in subsequent run. The TOC removal kinetics in SNSW by H. perleve fitted very well with a S-shaped curve and a Logistic model equation (R(2) = 0.999). In different volumes of SNSW with a fixed initial TOC concentration, the weight/volume ratio of sponge biomass and SFNSW was optimized at 1.46 g-fresh sponge/1-L SNSW to achieve the maximum TOC removal. When co-cultured with marine fish Fugu rubripes for 15 days, H. perleve removed TOC excreted by F. rubripes with similar retention rates of ca. 0.15 mg/h . g-fresh sponge, and the sponge biomass increased by 22.8%.     

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.     

Physiological consequences of the salmon louse (Lepeophtheirus salmonis) on juvenile pink salmon (Oncorhynchus gorbuscha): implications for wild salmon ecology and management, and for salmon aquaculture

Pink salmon, Oncorhynchus gorbuscha, are the most abundant wild salmon species and are thought of as an indicator of ecosystem health. The salmon louse, Lepeophtheirus salmonis, is endemic to pink salmon habitat but these ectoparasites have been implicated in reducing local pink salmon populations in the Broughton Archipelago, British Columbia. This allegation arose largely because juvenile pink salmon migrate past commercial open net salmon farms, which are known to incubate the salmon louse. Juvenile pink salmon are thought to be especially sensitive to this ectoparasite because they enter the sea at such a small size (approx. 0.2 g). Here, we describe how 'no effect' thresholds for salmon louse sublethal impacts on juvenile pink salmon were determined using physiological principles. These data were accepted by environmental managers and are being used to minimize the impact of salmon aquaculture on wild pink salmon populations.     

Freshwater salmon aquaculture in Chile and transferable antimicrobial resistance

Large amounts of antimicrobials are used in salmonid aquaculture in Chile. Most are used in marine aquaculture, but appreciable amounts are also employed in freshwater aquaculture. Much research and many publications have examined transferable antimicrobial resistance in bacteria isolated from marine salmon farms, but much less attention has been paid to this area in freshwater salmon farming. A recent paper by Domínguez et al. (2019) has as least in part remedied this situation. We now comment on some of its interpretations and have attempted to point out its areas of strength and weakness in light of the published scientific literature. Seen in this setting, the important results presented by Domínguez et al. (2019) underline the need for increased awareness of the challenge to animal and human health posed by excessive use of antimicrobials in aquaculture.     

Mechanisms prevalent during bioremediation of wastewaters from the pulp and paper industry

Bioremediation of wastewaters represents an important treatment methodology, especially when examined against the backdrop of ever-stricter legislation that is evolving in order to regulate effluent release into the environment. It has been reported that bioremediation specifically holds promise in solving environmental problems. Crucial questions surrounding the treatment of effluents include: efficiency of the process, economic feasibility, legal requirements, and the mechanisms involved in the remediation process. Of all these issues mentioned, the last requires special attention. This paper investigates these matters and focuses on techniques that are currently employed to determine the efficiency of bioremediation and mechanisms involved therein. The physiological significance of biosorption is also examined, as this subject has not been fully addressed in previous publications.     

A global assessment of salmon aquaculture impacts on wild salmonids

Since the late 1980s, wild salmon catch and abundance have declined dramatically in the North Atlantic and in much of the northeastern Pacific south of Alaska. In these areas, there has been a concomitant increase in the production of farmed salmon. Previous studies have shown negative impacts on wild salmonids, but these results have been difficult to translate into predictions of change in wild population survival and abundance. We compared marine survival of salmonids in areas with salmon farming to adjacent areas without farms in Scotland, Ireland, Atlantic Canada, and Pacific Canada to estimate changes in marine survival concurrent with the growth of salmon aquaculture. Through a meta-analysis of existing data, we show a reduction in survival or abundance of Atlantic salmon; sea trout; and pink, chum, and coho salmon in association with increased production of farmed salmon. In many cases, these reductions in survival or abundance are greater than 50%. Meta-analytic estimates of the mean effect are significant and negative, suggesting that salmon farming has reduced survival of wild salmon and trout in many populations and countries.     

Mathematical modeling of the integrated process of mercury bioremediation in the industrial bioreactor

The mathematical model of the integrated process of mercury contaminated wastewater bioremediation in a fixed-bed industrial bioreactor is presented. An activated carbon packing in the bioreactor plays the role of an adsorbent for ionic mercury and at the same time of a carrier material for immobilization of mercury-reducing bacteria. The model includes three basic stages of the bioremediation process: mass transfer in the liquid phase, adsorption of mercury onto activated carbon and ionic mercury bioreduction to Hg(0) by immobilized microorganisms. Model calculations were verified using experimental data obtained during the process of industrial wastewater bioremediation in the bioreactor of 1 m³ volume. It was found that the presented model reflects the properties of the real system quite well. Numerical simulation of the bioremediation process confirmed the experimentally observed positive effect of the integration of ionic mercury adsorption and bioreduction in one apparatus.     

An integrated closed system for fish-plankton aquaculture in Amazonian fresh water

A prototype of an integrated closed system for fish-plankton aquaculture was developed in Iquitos (Peruvian Amazonia) in order to cultivate the Tiger Catfish, Pseudoplatystoma punctifer (Castelnau, 1855). This freshwater recirculating system consisted of two linked sewage tanks with an intensive rearing unit (a cage) for P. punctifer placed in the first, and with a fish-plankton trophic chain replacing the filters commonly used in clear water closed systems. Detritivorous and zooplanktivorous fishes (Loricariidae and Cichlidae), maintained without external feeding in the sewage volume, mineralized organic matter and permitted the stabilization of the phytoplankton biomass. Water exchange and organic waste discharge were not necessary. In this paper we describe the processes undertaken to equilibrate this ecosystem: first the elimination of an un-adapted spiny alga, Golenkinia sp., whose proliferation was favored by the presence of a small rotifer, Trichocerca sp., and second the control of this rotifer proliferation via the introduction of two cichlid species, Acaronia nassa Heckel, 1840 and Satanoperca jurupari Heckel, 1840, in the sewage part. This favored some development of the green algae Nannochloris sp. and Chlorella sp. At that time we took the opportunity to begin a 3-month rearing test of P. punctifer. The mean specific growth rate and feed conversion ratio (FCR) of P. punctifer were 1.43 and 1.27, respectively, and the global FCR, including fish in the sewage part, was 1.08. This system has proven to be suitable for growing P. punctifer juveniles out to adult, and provides several practical advantages compared with traditional recirculating clear water systems, which use a combination of mechanical and biological filters and require periodic waste removal, leading to water and organic matter losses.     

真江蓠(Gracilaria verrucosa)对网箱养殖海区的生态修复及生态养殖匹配模式

2006年8～9月,在浙江象山港花鲈(Lateolabrax japonicus)养殖网箱中吊养真江蓠(Gracilaria verrucosa)对网箱养殖造成的水体富营养化进行生态修复研究.通过45d内的平面监测、定点跟踪监测和断面监测,结果表明:该网箱养殖区水体呈严重富营养化状态,营养状态指数(E)为32.00,其营养盐分布由高浓度的中心区向周围150m非养殖水域扩散;真江蓠对养殖区的富营养化海水具有较好的修复效果:江蓠生态修复区及其相邻网箱中水体PO4-P、NO2-N、NH4-N和NO3-N含量显著低于非修复区(P＜0.01),修复区海水PO4-P、NO2-N、NH4-N和NO3-N浓度比非修复区分别降低22%～58%、24%～48%、22%～61%和24%～47%.养殖真江蓠45d后,修复区水体DO浓度和透明度显著高于非修复区(P＜0.05),DO平均提高28%,透明度平均提高30%;而修复区水体Chl-a浓度显著低于非修复区(P＜0.05),平均降低49%.通过建立基于N平衡的鱼藻生态养殖模式,每收获1kg花鲈至少需要匹配江蓠4.7 kg wet wt才可实现对鱼类排放N的完全吸收.因此网箱内栽培江蓠的混合生态养殖模式,可平衡因经济动物养殖所带来的额外营养负荷,有利于实现动物养殖环境的自我修复.     

International cooperation in salmon fisheries and a comparative law perspective on the salmon and ocean ranching industry

Abstract

The salmon industry has steadily developed during the last two decades, leading to an increasing awareness about the legal problems that need to be solved. Both production in ocean ranching and in captivity have prompted the enactment of important rules of international and domestic law. While international law has provided for a basic regulatory framework, embodied in the United Nations Convention on the Law of the Sea and a number of regional and bilateral treaties, domestic law has concentrated on the specific technical issues that relate to conservation, fishing rights, and organization of the industry generally.

The article discusses the aggregate of legal rules applicable to salmon production, including the comparative law perspective emerging from the national legislations of the main producers in the world. Various legal and economic models are identified and their incidence on the industry is examined in light of actual experiences. The rules of international law in the field are becoming consolidated, and domestic legislation is contributing new insights into the matter while, in addition, exercising a strong influence in the formation of customary law.     

Assimilation of inorganic nutrients from salmon (Salmo salar) farming by the macroalgae (Saccharina latissima) in an exposed coastal environment: implications for integrated multi-trophic aquaculture

This paper investigated the assimilation of dissolved inorganic nitrogen (DIN) in Saccharina latissima in proximity to salmon cages in coastal waters. The bioassays were performed on plants from three stations located in the vicinity of a salmon farm (Salmo salar) in exposed waters at Tristein (63° 52′ N, 9° 37′ E) in Central Norway. The growth, the C and N content, and the nitrogen isotope ratios (δ¹⁵N) of S. latissima were monitored over 1 year. The DIN concentrations in seawater were higher at the salmon farm stations than at the reference station during the winter, and the N/P ratio at the salmon farm stations was higher from September to January and in June. S. latissima at the salmon farm stations grew faster than at the reference station. The length of S. latissima increased by 50 % when integrated with the salmon farm compared to the reference station. The N content of S. latissima was positively correlated to the DIN concentration in seawater (p?<?0.05), but the increased N supply from salmon did not result in N accumulation in S. latissima at the salmon farm station because of the dilution by a higher growth rate. The δ¹⁵N in S. latissima was higher at the salmon farm station from April to June and changed in the direction of the δ¹⁵N signature in urine. This indicated that N in S. latissima at the salmon farm station partly originated from the salmon. One hectare of S. latissima may absorb 0.8～1.2 t N during one growth season. Large-scale cultivation of S. latissima should be considered to mitigate the environmental effects of DIN wastes from salmon farms.     

海带养殖在桑沟湾多营养层次综合养殖系统中的生态功能

采用现场和实验生态学方法研究了大型经济海藻——海带(Saccharina japonica)的生长、光合作用和氮营养盐的吸收特性。实验结果表明:在1个生长周期内(约200d),海带的湿重与养殖天数呈明显的幂函数(W=1.3886 t~(1.362),R~2=0.9611),海带湿重是长度的幂函数(W=0.0071 L~(2.0882),R~2=0.9392);海带的光合作用放氧速率(O_2mg/h)与湿重(g)具有明显的线性相关(R~2范围为0.950—0.981),直线斜率(反应单位时间单位重量光合作用放氧速率)的变化范围为0.096—0.195(平均0.191),养殖初期单位鲜重的光合放氧能力较弱,后期趋于稳定;不同部位海带藻片对TIN的吸收速率不同,中带部上部(60—110cm)和基部(20—50cm)的吸收速率大于中带部下部(150—200cm)和边缘部,氮饥饿后最初0.5—1h对TIN的吸收速率最高(0.6μmol/g WW),培养24h可去除介质中TIN(初始浓度24.2μmol/L,密度4g/L)的64.2%—97.1%,10℃条件下藻片对营养盐的吸收率和去除率均大于4℃。海带藻片对NO_3-N的吸收速率大于对NH_4-N的吸收速率,24h后对NO_3-N的收速率趋于稳定。结果显示,海带具有较高的生长速度、光合作用产氧和营养盐吸收能力。海带养殖后期,每天可以增加氧气28.8g/m2(光周期按14h计算),收获时海带的平均碳氮含量分别为33.1%和1.8%,以桑沟湾海带养殖产量8.45万t计算,每年可移除2.8万t碳和1538t氮,海带在多营养层次综合养殖系统中具有较高的生态功能。     

Effect of ammonia content in the biodegradability of the salmon industry wastes

Lately, efforts put into solving the serious environmental problems caused by the accumulation of liquid, gaseous or solid industrial residues, have been greatly increased, being solid wastes the last ones to be considered. This work studies the anaerobic biodegradation of salmon waste produced by death in the farming process. The results obtained: 61.99% degradation (expressed in volatile solids abatement), with a methane productivity of 535.66?l?CH₄/kg_d.k. in studies done to samples with 1%?w/v of dry residue, show that the anaerobic technology is adequate to treat these wastes. Runs performed with higher solid contents (7, 13 and 20%?w/v) showed an ammonia accumulation, coming from protein degradation. They represent an upper limit of the system studied at a maximum value of ammonia nitrogen of 3.5?g/l attained, amount which hinders the further increase of solid matter in the tests. With the results obtained during this study, two inhibition models were analyzed (the Luong model and one proposed by the authors), which allow the prediction of the performance of the system studied.     

Potential of pure and mixed cultures of Cladosporium cladosporioides and Geotrichum candidum for application in bioremediation and detergent industry

The effect of ethoxylated oleyl–cetyl alcohol (Henkel, “Merima”, Serbia) on the growth and metabolic activity of Cladosporium cladosporioides, Geotrichum candidum and their mixed culture was in the focus of this paper. The cultures were grown in Czapek-Dox liquid nutrient medium with the addition of 0.5% pollutant and without it. The physico-chemical and biochemical changes of pH, the total biomass dry weight, the quantity of free and total organic acids, proteolytic activity and the quality of carbohydrates were evaluated from 4th to 19th day of fungal growth. The pollutant caused an inhibitory effect on biomass dry weight of C. cladosporioides and G. candidum for 10.36% and 4.65% respectively, and stimulatory effect on biomass of mixed culture for 3.80%. The pollutant had influence on the decrease in pH value of the media in the phase of culture growth, and pH changes were correlated with the amount of excreted total organic acids. The highest quantity of free and total organic acids was noted in media with pollutant of mixed culture and C. cladosporioides, respectively. The alkaline protease activities of C. cladosporioides, G. candidum and mixed culture were enhanced by addition of pollutant for 56.88%, 55.84% and 30.94% respectively. The obtained results indicate the potential of both pure and mixed cultures in mycoremediation environment contaminated by alcohol ethoxylated and detergent industry.