Volume regulation in glutathione-treated brook trout (Salvelinus fontinalis) erythrocytes

Brook trout erythrocytes that were washed with and suspended in Ringer's solution with reduced glutathione (1.0 mM) maintained steady state cell volume for up to 24h, while those without the thiol-protective agent steadily shrank. Changes in cell volume (measured as packed cell volume, PCV) were evoked by acidic media (Ringer's at pH 6.8), hypoosmotic solutions (or both) and intracellular K⁺ and Cl⁻ concentrations were monitored over 4h. Acid-swollen cells failed to volume regulate or release K⁺ but had significantly elevated intracellular Cl⁻ Osmotically-swollen cells at pH 7.8 but not at pH 6.8 underwent regulatory volume decrease (RVD) and returned to initial levels in 2h, accompanied by release of K⁺ and Cl⁻ In contrast, osmotically-shrunken cells did not show regulatory volume increase. The regulatory volume decrease and concomitant K⁺ release were dependent on Cl⁻ implying a direct or indirect coupling of K⁺ to Cl⁻ transport in volume regulation. RVD was partially blocked by 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS, 0.1 mM), an anion exchange blocker, but was unaffected by amiloride (1.0 mM) which blocks Na⁺/H⁺ exchange. Amiloride and DIDS prevented the swelling response to low pH but had no effect on control cells, suggesting involvement of Na⁺/H⁺ and Cl⁻/HCO₃ ⁻ exchanges in acid-induced cell swelling. Quinine (1.0 mM) a known blocker of K⁺ channels, exacerbated the osmotically-induced swelling but had little effect on the subsequent RVD and release of KCl. The results suggest that low extracellular pH inhibits neutral C⁻-dependent K⁺ release and the resultant regulatory volume decrease in osmotically-swollen cells.     

Tissue concentrations of RNA and protein for juvenile brook trout (Salvelinus fontinalis): lagged responses to fluctuations in food availability

To be useful as short-term indices of nutritional status when food availability varies, wet weight-at-length and tissue concentrations of nucleic acids and protein must covary closely with a fish's recent feeding history. We measured changes in these indices for young brook trout (Salvelinus fontinalis) (fork length: 20–34 mm) reared under alternating, 4 to 5 d periods of food provisioning and food deprivation. Weight-at-length corresponded closely with current feeding conditions, being higher when the trout were fed than when they were deprived. Concentrations of RNA and protein, however, did not correspond closely with current feeding conditions. Instead, there were significant carry-over effects whereby responses to feeding conditions experienced in one treatment period were not exhibited until the following treatment period. Food provisioning had positive carry-over effects on concentrations of RNA and protein while food deprivation had negative carry-over effects. Consequently, food-deprived trout sometimes had higher concentrations of RNA and protein than well fed trout. Since wild fish may experience short-term fluctuations in food availability, lagged responses in concentrations of nucleic acids or protein like those reported here could hamper attempts to use these biochemical measures to assess the nutritional status of juvenile fish in the field.Author to whom all correspondence should be addressed.     

温度对拟穴青蟹循环水养殖系统微生物群落结构的影响

为探究温度对拟穴青蟹(Scylla paramamosain)循环养殖水体中微生物群落的影响,深入理解环境因子与养殖水体微生物群落之间的相关性。在水温分别为18℃、22℃、26℃、30℃和32℃的循环养殖系统中进行拟穴青蟹养殖,采用16S rRNA高通量测序技术对不同温度下的养殖水体微生物群落组成进行分析。结果表明:(1) Alpha多样性指数显示5组水样中细菌群落多样性指数大小为t26t22t30t32t18,物种丰度大小为t22t26t32t30t18。温度可以导致养殖水体中微生物群落多样性发生变化,但并未发现二者之间直接的相关性。(2) 5种温度下的养殖系统中细菌群落共有31门、43纲、94目、185科和351属,变形菌门(Proteobacteria)为循环养殖水体中绝对优势菌门。在养殖系统水温为26℃时,养殖水体中氮磷污染物含量相对较高,其水中脱氮除磷菌属的相对丰度也显著高于其他4组。(3)由花瓣图和UPGMA聚类分析图进行相似性分析可知,水体微生物群落对温度的变化有着良好的响应, 5组水样的细菌群落结构总体相似性较低,其中最高温度32℃和最低温度18℃的水体中细菌群落结构最为相似。(4)水体中微生物群落结构和与环境因子的相关性分析显示,氮磷营养盐中的总磷(TP)和硝酸盐(NO3–-N)对水中微生物群落特征具有显著性影响,而温度是导致养殖水体中氮磷营养盐差异化的主要原因。上述研究结果初步解释了温度对拟穴青蟹循环养殖水微生物群落的作用机制,为下一步深入研究拟穴青蟹循环水养殖系统中环境变化与微生物的相互关系提供参考。     

珠江三角洲地区大口黑鲈池塘养殖系统的能值评估

为评价珠江三角洲地区大口黑鲈池塘养殖系统的生态经济性能,实验以能值理论为基础,定量分析该系统的能流和物流特点,通过建立能值评价指标体系,综合评估该系统的环境影响及可持续性。结果显示,大口黑鲈养殖系统投入的资源分为可更新资源(太阳能、风能、雨水能、地球循环能和河水能)和购买的外部资源(设施、苗种、电能、饵料、药品、劳动力、租金、维护费)两部分。养殖系统投入的总能值为4.51×10~(17)sej/(hm~2·a),其中可更新资源能值总和为1.24×10~(16) sej/(hm~2·a),占总投入能值的2.75%。河水能在可更新资源中所占比例最大,为9.77×10~(15) sej/(hm~2·a),占总投入能值的2.17%。购买的外部资源能值总和为4.38×10~(17) sej/(hm~2·a),占总投入能值的97.25%。饵料投入在购买的外部资源中所占比例最大,其能值为3.49×10~(17) sej/(hm~2·a),占总投入能值的77.33%,其次是劳动力,能值为2.29×10~(16) sej/(hm~2·a),占总投入能值的5.08%。大口黑鲈池塘养殖系统太阳能值转换率TR为2.18×106 sej/J,产出能值交换率EERY为2.028,能值产出率EYR为1.028,环境负载率ELR为35.39,能值持续性指数ESI为0.029,可持续性发展的能值指数EISD为0.059。大口黑鲈池塘养殖系统经济效益较高,但过多依赖购买的外部资源,对环境压力较大,可持续性较差。减少饵料投喂量、提高饵料利用率(如选择优质配合饲料及添加剂、改进投喂策略等)以及开展综合养殖是提高珠江三角洲地区大口黑鲈养殖系统持续性、减小环境负载率的有效途径。     

基于转录组数据的溪红点鲑微卫星标记筛选及引进群体遗传结构

为了深入了解引进溪红点鲑种质遗传结构状况,本研究利用溪红点鲑转录组数据设计四核苷酸重复微卫星引物1 081对,选择其中200对进行引物合成,经过筛选鉴定共获得111个特异性好且扩增效率高的微卫星标记,用其中27个多态性标记比较分析了溪红点鲑引进群体和养殖群体的遗传多样性。结果显示,27个微卫星位点在2个群体中共检测到171个等位基因,多态性信息含量(PIC)为0.426 0～0.877 4,平均为0.673 1,其中23个位点高度多态(PIC≥0.5)。引进群体和养殖群体的平均等位基因数(Na)分别为5.555 6和4.444 4;平均有效等位基因数(Ne)分别为3.914 5和3.108 2;平均观测杂合度(Ho)分别为0.356 2和0.265 0;平均期望杂合度(He)分别为0.700 2和0.621 0;平均PIC分别为0.640 9和0.555 5。引进群体和养殖群体的遗传参数t检验结果显示,养殖群体的5项遗传多样性参数均显著或极显著低于引进群体,表明尽管溪红点鲑养殖群体的PIC仍处于高度多态水平(PIC≥0.5),但是经过多代群体自繁,已经出现等位基因严重富集的现象。经Bo...     

大西洋鲑、三倍体虹鳟和金鳟的肌肉营养成分与品质特性

为了解大西洋鲑(Salmo salar)、三倍体虹鳟(Oncorhynchus mykiss)、金鳟(Oncorhynchus mykiss)3种鱼肌肉营养成分和品质特性,利用生化分析、物性分析方法分析3种鱼肌肉的营养成分、氨基酸和脂肪酸组成、肉色、系水力和质构特性。结果表明,大西洋鲑、三倍体虹鳟、金鳟肌肉的水分质量分数分别为62.91%、67.15%、73.02%,粗蛋白质量分数分别为22.39%、21.03%、22.11%,粗脂肪质量分数分别为14.64%、17.16%、5.11%。3种鱼肌肉的滴水损失、黄色值(b~*)、羟脯氨酸含量、内聚性均显著不差异(P0.05)。3种鱼肌肉的硬度和咀嚼性由低到高依次为大西洋鲑、三倍体虹鳟、金鳟,而pH值的结果则与之相反(P0.05)。大西洋鲑和三倍体虹鳟肌肉的灰分、解冻损失、蒸煮损失、回复性、弹性和红色值(a~*)差异不显著(P0.05),但灰分、蒸煮损失、回复性均小于金鳟肌肉的对应指标(P0.05),弹性和红色值(a~*)则均大于金鳟肌肉的对应指标(P0.05)。大西洋鲑、三倍体虹鳟、金鳟肌肉中必需氨基酸含量占氨基酸总量分别为42.28%、41.84%、41.63%(质量分数),必需氨基酸/非必需氨基酸(EAA/NEAA)比值分别为73.25%、71.94%、71.32%,均符合联合国粮农组织/世界卫生组织(FAO/WHO)对优质蛋白质的评价标准;3种鱼肌肉中均检测到22种脂肪酸,组成丰富,其中不饱和脂肪酸含量较高。综上所述,3种鱼的肌肉都是符合人体营养需求的优质水产品,其中大西洋鲑和三倍体虹鳟肉质接近,且都优于金鳟的肉质。     

Growth in Arctic charr and rainbow trout fed temporally concentrated or spaced daily meals

The effect on growth of distributing feed over a few hours compared tomore frequent meals was tested on 1+ Arctic charr (Salvelinus alpinus L.) and 1+ rainbow trout (Oncorhynchus mykiss Walbaum). Triplicate hatchery groups for each treatment were fed at a ration level of 1%/dayeither with few meals (8 times per day divided into morning and evening)or with frequent meals (32 meals equally distributed during the day). Wefound an opposite effect of meal frequency on growth in the two species.Low feeding intensity (8 meals per day) had a significantly positive effecton growth in rainbow trout but a significantly negative effect on growth inArctic charr when compared to feeding the fish frequent meals. Theopposite response to meal frequency is likely to be an effect of thedifferences in activity during feeding. Rainbow trout feed much moreaggressively than charr which can result in feeding being a more stressfulevent. In this experiment, the specific growth rate was lower and the feedconversion ratio higher for Arctic charr compared to rainbow trout.     

鳜养殖概况及摄食调控机制研究进展

鳜是我国名贵的淡水经济鱼类,2019年其养殖产量已达33万t。本文从养殖现状、养殖模式及良种选育等方面介绍鳜的养殖概况。同时,鳜摄食习性独特,终生以活鱼为食。养殖生产中,主要以活饵料鱼直接饲喂,这种以鱼养鱼的方式不仅资源利用率低,对环境和资源的破坏也极大。据此,本文从环境因素和饵料性质等方面概述了影响鳜摄食的外在因素,并从摄食感觉器官和摄食调控因子剖析鳜摄食特性的内在因素,这有助于通过人工干预的方式调整鳜的摄食习性,为其转食配合饲料提供必要的支撑。此外,需加强鳜摄食调控机制及营养生理需求特性的研究,实现鳜配合饲料的突破,促进其养殖业的绿色健康发展。     

The growth of disk abalone, Haliotis discus hannai at different culture densities in a pilot-scale recirculating aquaculture system with a baffled culture tank

The growth rate of disk abalone, Haliotis discus hannai, energy consumption and changes in water quality were monitored in a pilot-scale recirculating aquaculture system (RAS) for 155 days. Baffles were installed in the RAS culture tanks to enlarge the attachment area and clean out solid waste materials automatically by hydraulic force only. The experimental disk abalones, of shell length 24.5 ± 0.5 mm, were cultured at three stocking densities, 700, 1300 and 1910 individuals/m² bottom area, in triplicate. The abalones were fed with sea mustard, Undaria pinnatifida, once a week. The abalone feed conversion rates and daily growth rates ranged from 24.5 to 25.9 and 0.32 to 0.36%, respectively. Their daily shell increments and survival rates ranged from 67.7 to 78.6 μm/day and 87.6–92.2%, respectively. The growth in weight tended to decrease at a culture density of 1300 individuals/m² bottom area, while shell increments and survival rates were acceptable at this density. The total power consumption for heating was 1185.4 kW, comprising 30.2% of the total power consumption, while the average water exchange rate was only 2.9% per day. The total ammonia nitrogen stabilized below 0.07 mg/L, after conditioning of the biofilter. The NO₂⁻–N, NO₃⁻–N and total suspended solid concentrations were also maintained within acceptable ranges for the normal growth of disk abalone. The use of the RAS with these newly designed culture tanks for disk abalone culture produced 1300 individuals/m² bottom area with a water exchange rate of only 2.9% per day and used about one-tenth of the heat energy of a conventional flow-through system.     

Mass production of Rhodopseudomonas palustris as diet for aquaculture

Three different types of anaerobic fermentations were used for the mass production of the photosynthetic bacterium Rhodopseudomonas palustris as diet for aquaculture. The optimum agitation speed and malate concentration were 300 r.p.m. and 0.2% in the modified MYC medium, respectively. In batch fermentations of R. palustris, the maximum number of viable cells was 1.1×10¹⁰ c.f.u. ml⁻¹ with 2.65 g l⁻¹ of DCW, and the maximum specific growth rate and biomass productivity were estimated to be 0.12 h⁻¹ and 55 mg l⁻¹ h⁻¹, respectively. Crude protein content of R. palustris was about 72–74%. The composition of stearic acid and oleic acid of R. palustris was superior to those of Chlorella and yeasts, while that of other fatty acids tested was not. The amino acid profiles of the protein hydrolysate compared favorably with Food Agricultural Organization (FAO) guidelines. The biomass productivities from fed-batch experiments were found to be 50, 47 and 49 mg l⁻¹ h⁻¹ for linear, exponential, and sigmoidal feeding strategy, respectively. The maximum biomass productivity was found to be 112 mg l⁻¹ h⁻¹ in chemostat. Compared to growth in batch cultures, continuous fermentation yielded two times higher biomass productivity.     

Stocking density and cohort sampling effects on endocrine interactions in rainbow trout

Studies were conducted to explore the effect of cohort sampling and stocking density on the interactions between plasma growth hormone (GH), thyroid hormone and cortisol concentrations in rainbow trout. Depending on the experimental design, plasma GH concentrations were either suppressed, or elevated by sequential removal of cohorts from the holding aquarium. Since plasma cortisol concentrations consistently increased during cohort sampling, regardless of experimental design, it would appear that the apparent correlation (direct or inverse) is the result of concomitant changes, i.e. not necessarily a cause-effect relationship. Plasma GH concentrations of rainbow trout were not correlated with eviscerated body weight.Trout stocked at 150 kg m^–3 exhibited a significantly lower mean growth rate, hepatosomatic index, hepatic lipid reserve, plasma triiodo-l-thyronine (T₃) concentration andin vitro hepatic T₃ production than trout stocked at 60 kg m^–3. These observations are consistent with the former group being food deprived or ration restricted. Stocking density appeared to have no effect on plasma GH or cortisol concentrations, or on the pituitary-interrenal axis response to stressor challenge, or the thyroid tissue response to exogenous TSH challenge.     

Evidence of genotype–diet interactions in the response of rainbow trout (Oncorhynchus mykiss) clones to a diet with or without fishmeal at early growth

This study examined the genetic variability and genotype × diet interactions during early growth (initial mean body weight 1.2 g) among seven heterozygous clones of rainbow trout, Oncorhynchus mykiss. The clones were hand-fed a diet containing either fishmeal or plant proteins during a 49-day trial divided into two periods (P1, 26 days, and P2, 23 days). Weight, variation of weight within clone, feed intake, feed efficiency and mortality were calculated for both periods.There was a highly significant effect of diet and of clone for all traits at both periods, except for feed efficiency and mortality at P1. Highly significant interactions between diet and clone were also recorded for all these traits, except for mortality at P1. The occurrence of genotype × diet interactions when feeding juvenile rainbow trout with an all plant-protein diet indicates that a highly performing genotype on a fishmeal diet may perform poorly when fed a plant-protein diet. Interactions were found for the two major determinants of growth, i.e. feed intake and feed efficiency, showing that the dietary response differs according to the genotype. Monitoring of the within-clone variability of weight showed that a plant-based diet is likely to enhance the overall phenotypic variance in a population, whatever its initial genetic variability.     

凡纳滨对虾养殖环境及肠道微生物群落特征分析

为探究凡纳滨对虾养殖过程中其肠道和养殖环境微生物群落的结构及变化,本实验采用Illumina MiSeq测序平台,基于16S rRNA基因的测序结果,对46和86 d虾龄的凡纳滨对虾肠道以及养殖水样、底泥中的微生物群落进行分析。结果显示,86 d时微生物Shannon-Wiener多样性指数显著高于46 d,水样中的Shannon-Wiener指数显著低于底泥和凡纳滨对虾肠道;有35个门、70个纲、152个目、274个科以及420个属在水样、底泥和虾肠道中均能检测到,其中虾肠道和底泥间共有菌类较水样中更多。微生物群落随养殖时间增加发生变化,46与86 d的差异性门类为放线菌门、绿菌门、丝状杆菌门、浮霉状菌门和TM6,相对丰度随时间增加而增高。水样、底泥和虾肠道中有相对固定的优势菌群,在水样、底泥和虾肠道中主要的门类均为变形菌门、拟杆菌门和放线菌门,优势纲类为α变形菌纲、β变形菌纲以及放线菌纲,除此以外,虾肠道与底泥共有的优势纲为δ变形菌纲、γ变形菌纲以及芽单胞菌纲;从目、科、属的分类水平上看,水样、底泥和虾肠道中菌类相对丰度各异,鲜有明显重叠的优势菌类,在水样、底泥和虾肠道中均为一种未...     

Effect of peracetic acid on levels of geosmin, 2-methylisoborneol,and their potential producers in a recirculating aquaculture system for rearing rainbow trout (Oncorhynchus mykiss)

In recirculating aquaculture systems (RAS)s, off-flavors and odors, mainly caused by geosmin (GSM) and 2-methylisoborneol (MIB), can accumulate in the flesh of fish from RAS water, reducing the profitability of production. In this study, peracetic acid (PAA) was applied in three application intervals to pump sumps of rainbow trout (Oncorhynchus mykiss) reared in RAS. Using a real-time polymerase chain reaction (qPCR), the potential off-flavor producers were quantified using geoA and MIB synthase genes. Streptomyces was identified as the major GSM producer, and biofilters showed the highest number of potential off-flavor producers. Concentrations of GSM and MIB were analyzed in the circulating water and in the lateral part of the fish fillet. In water, concentrations up to 51 ng L⁻¹ (GSM) and 60.3 ng L⁻¹ (MIB) were found, while in the fillet, these were up to 9.8 ng g⁻¹ (GSM) and 10.2 ng g⁻¹ (MIB), decreasing with increasing number of PAA applications. PAA applications reduced the levels of off-flavor compounds, although this was insufficient to fully prevent the accumulation of GSM and MIB.     

Effect of the daily meal time on the growth of rainbow trout fed different ration levels

This study examined the effect of ration level and time of delivery of a single daily meal on the growth performance of rainbow trout held under constant water temperature and a natural photoperiod. Two similar trials were conducted, the first from March to July, 1992, using ration levels of 0.5, 1.5 and 2.5% BW d^–1 and the second from August 1992 to January 1993, using ration levels of 1.5, 2.0 and 2.5% BW d^–1.In five of the six treatment groups (three ration levels × two seasons), when the daily meal was presented in the post-dawn period the growth rate was lower than in trout fed at either mid-light or pre-dusk. No time-of-feeding effect was found when trout were fed excess rations. Specific growth rate (SGR) was not affected by feeding time, but was correlated with ration level; furthermore, there was a significant increase in SGR during the first section of the first trial and a significant decrease in the SGR throughout the duration of the second trial.Ration level was significantly correlated with condition factor, carcass visceral adipose tissue content and skeletal muscle lipid content, but there was no effect of the timing of the daily meal on these variables.     

The fatty acid composition of Nereis diversicolor cultured in an integrated recirculated system: Possible implications for aquaculture

The potential of solid waste originating from a recirculated fish culture system, i.e. faecal material, uneaten food pellets and bacterial biofilms was examined as food source for the marine polychaete Nereis diversicolor. These polychaetes could be a valuable food for fish if they provide essential fatty acids to the fish. Therefore, we analysed the fatty acid profiles from feed and faecal materials, the sediment as well as the cultured organisms — fish and several batches of N. diversicolor — from an integrated recirculating aquaculture system.The major fatty acids (saturated, monounsaturated and polyunsaturated) for all analysed fish feed, fish and faeces samples were C16:0, C18:1 and C22:6 (n − 3), accounting for 48% to 57% of the fatty acids in the samples. The major fatty acids within the sediment were C16:0, C18:1 and C18:3 (n − 3), accounting for 61% of the total fatty acids. The samples of N. diversicolor revealed C16:0, C18:1 and C20:5 (n − 3) as the major fatty acids. Combined, they accounted for 56% of the total fatty acids detected within the worm samples.The results indicate that a recycling or even an upgrade of excreted feed nutrients such as fatty acids, which were otherwise discharged, can be achieved through integrated aquaculture combining fish and worm culture.     

Effects of emulsified versus saline administration of GnRHa on induction of ovulation in rainbow trout, Oncorhynchus mykiss

The effects of saline-dissolved or Freund's incomplete adjuvant (FIA)-emulsified GnRHa treatment on the induction of ovulation in rainbow trout, Oncorhynchus mykiss, were examined. The FIA-emulsified GnRHa was first diluted in 0.25 ml physiological saline and then mixed with an equal volume of FIA. Fish were selected in the beginning of the spawning season and were allocated into four groups and were treated intraperitoneally with (a) 0.5 ml of emulsified GnRHa (GnRHa–FIA), (b) 0.5 ml saline-dissolved GnRHa in a single injection (GnRHa-1), (c) 0.5 ml saline-dissolved GnRHa in two injections spaced 1 d apart (GnRHa-2) and (d) 0.5 ml of saline (Control). The GnRHa dose in all hormone treatments was 25 µg kg^− 1. All fish in the FIA–GnRHa and GnRHa-2 groups ovulated within 10 and 11 d after treatment, respectively. In contrast, only 75% in the Control fish and 60% of the fish in the GnRHa-1 group ovulated within 36 d after treatment. None of the treatments caused any pre- or post-spawning mortality in the broodstock. Fertilization, eyeing and hatching percentages of the produced progeny were normal in all the treatment groups and did not differ significantly among them. In conclusion, FIA-emulsified GnRHa can be effective in advancing the onset of and synchronizing the ovulation of rainbow trout within a two-week period, thus shortening the egg collection period, without affecting broodstock survival and egg quality.     

Growth of rainbow trout fed a diet supplemented with earthworms,after chemical treatment

Whole frozen earthworms (Eisenia foetida) were evaluated as a partial replacement for commercial pellets for rainbow trout, Oncorhynchus mykiss. Earthworms were blanched and treated with concentrated sodium chloride (10%). Fish were submitted to four treatments: control fish were fed with a commercial diet and three groups of fish were fed with diets partially supplemented with earthworms. All fish showed the same appetite for the earthworm-supplemented diets as for the control diet during the course of the experiment (8 weeks). No significant differences (p > 0.05) were detected in the mean final body weights of all groups of fish. A significant decrease was found in the whole-carcass lipid content of fish fed diets containing 25%, 50% and 75% frozen earthworms. The results on growth rate and feed utilization efficiency of fish fed diets containing high levels of whole frozen worms suggested an adverse effect of worm incorporation, probably due to dietary energy/protein imbalance.     

Exploring Northeast American and Asian species of Porphyra for use in an integrated finfish-algal aquaculture system

Many aquaculture industries generate a nutrient-rich waste stream that can lead to eutrophication of coastal waters. To address this environmental issue, the bioremediation potential of several native Northeast American species of Porphyra was assessed and compared to the well-known Asian species. Porphyra thalli were cultured over 4 weeks at 15 °C at a stocking density of 0.4 g FW L^− 1. At 3- to 4-day intervals nutrient uptake, tissue N accumulation and phycobiliprotein concentration (PBP) were determined as functions of nitrogen (N) concentration (25-300 μM) and N source (nitrate vs. ammonium). Growth rates were measured weekly. Growth and tissue N reached maximal levels at inorganic N concentrations of 150-300 μM. Maximum growth rates ranged from 10% to 25% day^− 1, although induction of archeospores reduced average growth rates in many cases. No evidence of ammonium toxicity (reductions in growth rate) was observed; in fact, similar values were found with both N sources. Ammonium generally yielded higher PBP and tissue N contents than nitrate. Porphyra amplissima presented the highest growth rate, followed by the Asian Porphyra yezoensis. Under the experimental conditions, Porphyra spp. removed 70-100% of N within 3-4 days at N concentrations up to 150 μM, but was less efficient in removing inorganic phosphorus (35-91% removal). The highest tissue N and PBP concentrations were found at 150-300 μM of N, with N values close to 7% DW. Overall, Porphyra appears to be an excellent choice for bioremediation of moderately eutrophic effluents, with the added benefit that tissue may be harvested for sale.