一种贝类作为水产动物诱食剂的研究

一种贝类（ＡＳＬ）不仅蛋白质含量高,氨基酸组成也比较全面,高不饱和脂肪酸含量丰富,甜菜碱含量高达２８９ｍｇ／ｇ。向饲料中添加１％的ＡＳＬ粉,发现其对金鱼的诱食活性不仅显著高于空白对照组,而且显著高于化十香组;饲料中添加０３％的ＡＳＬ粉,异育银鲫摄食量显著高于对照组,六周增重率比对照组提高３３％,这些结果表明ＡＳＬ作为水产动物诱食剂具有很高的开发利用价值。     

浅海筏式养殖系统贝类养殖容量研究进展

据报道,以世界人均耕地计,中国人口以４亿为合适,按人均粮食５００ｋｇ／年计,中国人口以６亿为适度,按水资源来估算中国适度人口可为７亿。综合起来考虑,中国理想人口数量应在６．５亿左右［刘大椿等１９９５］,而我国实际人口已远远超过此数。很显然,只依靠耕地...     

The ecological role of bivalve shellfish aquaculture in the estuarine environment: A review with application to oyster and clam culture in West Coast (USA) estuaries

Aquaculture is viewed as a potential mechanism to meet the growing demand for seafood around the world. The future of bivalve shellfish aquaculture in the U.S. hinges on sustainable practices on the part of industry and a more consistent regulatory regime. Bivalve shellfish aquaculture is a recent practice relative to its history in other countries, beginning in the late 1800s along the U.S. West Coast where it is now well established with farm raised product utilizing land-based hatcheries and grow-out directly in numerous estuaries. Bivalve shellfish aquaculture can be viewed as a disturbance which modifies the estuarine system in three ways: 1) changes in material processes — bivalves process food and produce wastes; 2) addition of physical structure — aquaculture introduces the cultured organisms and in some cases a physical anchoring structure; and 3) pulse disturbances like harvest and bed maintenance disturb sediments, remove species in addition to the cultured organisms themselves, and change resource or habitat availability. In U.S. West Coast estuaries, water column and sediment nutrient concentrations are relatively high and influenced by large tidal exchange and proximity to deeper nearshore ocean waters where upwelling controls production during summer months. Bivalves are unlikely to influence material processes except at local bed scales in these systems, although estuary-wide effects could appear as the fraction of cultured area rises or in poorly flushed bays. Bivalve culture clearly modifies estuarine habitat at local community and at landscape scales and effects are most often evaluated against existing structured habitat in the form of submerged aquatic vegetation. Individual activities act as pulse disturbances and the recovery of eelgrass (Zostera marina) to pre-disturbance levels is variable (< 2 to > 5 years). The extent of disturbance depends on the aquaculture practice and the distribution of eelgrass reflects a balance of space competition, pulse disturbance and recovery, and is therefore at dynamic equilibrium on aquaculture beds. Structure provided by aquaculture appears functionally similar to eelgrass for small benthic infauna and mobile epibenthic fauna while use of aquaculture as habitat by larger more mobile invertebrates and fish depends on mobility and varies with life-history stage and taxon being evaluated. Scale seems a very important management consideration and further research at estuarine landscape scales, especially for habitat use by important invertebrates and fish, may prove useful in designing and implementing best management practices. Though local and short term effects from aquaculture are clearly evident in U.S. West Coast estuaries, bivalve aquaculture does not remove area from the estuary or degrade water quality like other anthropogenic influences, and thus has not been implicated in shifts to alternate states or reduced adaptive capacity of the larger ecological system.     

双壳贝类染色体标本制备技术的优化

本研究以牡蛎、咬齿牡蛎鳃细胞为材料,采用PHA处理法、低温同步化法及活体去壳法进行预处理,制作成染色体标本;以马氏珠母贝、企鹅珍珠贝担轮幼虫为材料,采用PHA促繁殖获取胚胎法,制作胚胎染色体标本。对不同时间不同处理方式获得牡蛎染色体分裂相比例、PHA促繁殖获取胚胎法获得马氏珠母贝染色体分裂相比例进行统计。结果发现,PHA处理法在24h时能获取最多分裂相（3．50‰）,低温同步化法在72h时能获得最多分裂相（2．20‰）,活体去壳法始终保持较高分裂相比例（3．60‰）,PHA促繁殖获取胚胎法获得最大分裂相比例（10．00‰）。4种方法都能获得理想的中期分裂相数目。其中,低温同步化法缺点是温度难控制、预处理时间长;活体去壳法易导致贝类死亡;PHA促受精获取胚胎法缺点是胚胎的获取受繁殖季节限制。PHA处理法预处理时间短、获取分裂相数目多,无疑是贝类成体染色体制备的最好的方法。同时,PHA也为贝类人工繁殖提供了一种更为有效的手段。     

Production of microalgal concentrates by flocculation and their assessment as aquaculture feeds

A novel technique was developed for the flocculation of marine microalgae commonly used in aquaculture. The process entailed an adjustment of pH of culture to between 10 and 10.6 using NaOH, followed by addition of a non-ionic polymer Magnafloc LT-25 to a final concentration of 0.5 mg L⁻¹. The ensuing flocculate was harvested, and neutralised giving a final concentration factor of between 200- and 800-fold. This process was successfully applied to harvest cells of Chaetoceros calcitrans, C. muelleri, Thalassiosira pseudonana, Attheya septentrionalis, Nitzschia closterium, Skeletonema sp., Tetraselmis suecica and Rhodomonas salina, with efficiencies ≥80%. The process was rapid, simple and inexpensive, and relatively cost neutral with increasing volume (cf. concentration by centrifugation). Harvested material was readily disaggregated to single cell suspensions by dilution in seawater and mild agitation. Microscopic examination of the cells showed them to be indistinguishable from corresponding non-flocculated cells. Chlorophyll analysis of concentrates prepared from cultures of ≤130 L showed minimal degradation after 2 weeks storage.

Concentrates of T. pseudonana prepared using pH-induced flocculation gave better growth of juvenile Pacific oysters (Crassostrea gigas) than concentrates prepared by ferric flocculation, or centrifuged concentrates using a cream separator or laboratory centrifuge. In follow up experiments, concentrates prepared from 1000 L Chaetoceros muelleri cultures were effective as supplementary diets to improve the growth of juvenile C. gigas and the scallop Pecten fumatus reared under commercial conditions, though not as effective as the corresponding live algae. The experiments demonstrated a proof-of-concept for a commercial application of concentrates prepared by flocculation, especially for use at a remote nursery without on-site mass-algal culture facilities.     

Growth and survival of the pearl oyster Pinctada imbricata (Röding 1758) in supended and bottom culture in the Golfo de Cariaco, Venezuela

We evaluated growth and survival rates of Pinctadaimbricata in relation to environmental changes during nine months insuspended and bottom culture in the Golfo de Cariaco, Venezuela. Juveniles,measuring 13 mm in length, were cultured using two methods, (1) inSpanish-type baskets suspended at 3–4 m in depth from a longline and (2) in baskets embedded on the seabed (7–8 m indepth). At monthly intervals, we quantified mortality and took a sample ofoysters to determine shell length (dorsal-ventral axis) and the dry mass of theshell, muscle and remaining tissues. We also quantified the dry mass of foulingon the shells (a potentially important environmental factor). Survival rateswere slightly higher in suspended culture (98–100%), although notsignificantly higher than on the bottom. The growth rate was higher in suspendedculture than on the bottom culture, and the difference between culture methodswas greater for tissue and shell biomass than for shell dimensions. At the endof the study, oysters measured 55 mm in shell length for oysters insuspension and 45 mm for those on the bottom. Although growth wasnot significantly correlated with any environmental factor, it tended toincrease with increases in chlorophyll a during periods ofupwelling, thus suggesting that phytoplankton abundance enhanced the growth ofPinctada imbricata. The pearl oyster Pinctadaimbricata should be an excellent species for aquaculture activities,given its high rates of growth and survival in suspended culture and itseconomic importance in the Caribbean region.     

Inhibition of embryo development of the commercial bivalves Ruditapes decussatus and Mytilus galloprovincialis by trace metals; implications for the implementation of seawater quality criteria

This study evaluates the risk posed by trace metals on the culture of bivalves in the Galician coast (NW Iberian Peninsula), which depends on collection of natural seed and larval rearing with natural seawater in hatcheries. With this aim, toxicity tests were carried out with embryos of the commercial bivalves Ruditapes decussatus and Mytilus galloprovincialis, and the toxicity of Hg, Cu, Zn, Cd and Pb was quantified in terms of median effective concentration (EC₅₀) and toxicity threshold, using embryogenesis success as endpoint. The EC₅₀ values ranged from 4 to 10 μg/l for Hg and Cu, from 100 to 300 μg/l for Zn and Pb, and from 400 to 2000 μg/l for Cd. The toxicity of copper and zinc combinations could be predicted using a strictly additive model. Effective concentrations found were compared to measured metal concentrations in the Galician Rias, and to local and international seawater quality criteria, in an attempt to evaluate the risk posed by metals to these commercial species. Zinc and especially copper pollution were found to represent a serious threat in certain areas. Furthermore, local seawater quality criteria recently implemented are, in the case of copper and zinc, two orders of magnitude too high to offer any protection for these sensitive early life stages of bivalves.     

贝类在水污染预警与治理中的作用

综述了利用贝类的种群动态及定量分析贝类软体和壳体等介质中污染物含量来监测水污染状况的研究成果,讨论了利用贝类进行水体污染生物治理的作用,并简要论述了贝类在水环境生态修复中的应用前景。     

Replacement of living microalgae with spray-dried diets for the marine mussel Mytilus galloprovincialis

Growth experiments were carried out in which juvenile mussels Mytilus galloprovincialis were fed diets composed of spray-dried algal products (Sanders Brine Shrimp) which included Schizochytrium sp. (SZ; Docosa Gold), Spirulina platensis (Sp) [=Arthrospira platensis] and Hematococcus pluvialis (H) either alone or in combination with partial rations of living microalgae. Growth of mussels fed 1/4 ration of living algae plus a mixed supplement of 50/50% w/w SZ:Sp grew significantly (SNK; P<0.05) faster than mussels fed a full live algal ration. Furthermore, growth (both wet weight and dry organic weight increase) of mussels fed diets composed of either 70/30% w/w SZ: ground Sp (GSp; <20 μm) or 25/50/25% w/w H:SZ:GSp was significantly (PLSD; P<0.05) greater than that of mussels fed an equal ration (by dry weight) of living Tahitian Isochrysis galbana.     

Analysis and cytologic characterization of hemocytes from freshwater mussels (Quadrula sp.)

Background: Freshwater mussels are among the most endangered taxa in North America and minimally invasive techniques to evaluate their health are needed. Objective: The objective of this study was to develop a standardized approach for identifying and enumerating the cellular components of freshwater mussel hemolymph. Methods: Hemocyte clumping, total hemocyte count, and hemocyte morphology were compared in untreated hemolymph or hemolymph treated with formalin, sodium citrate, sodium heparin, EDTA, water, or l ‐cysteine. Morphology was then used to categorize hemocytes and perform a 100‐cell differential. Results: Treatment with formalin or >25 mg/mL l ‐cysteine reduced hemocyte clumping, although only formalin significantly increased the total hemocyte count. However, formalin also induced crenation that impaired hemocyte identification. Both EDTA and sodium citrate‐induced hemocyte degranulation while sodium citrate and >40 mg/mL l ‐cysteine‐induced cell lysis. Hemocytes could be categorized into 2 groups of granulocytes (eosinophilic or basophilic) and 2 groups of agranulocytes (large or small) for performing a cytologic differential. The differential was not significantly altered by anticoagulant treatments providing cell morphology was adequate for obtaining a differential. Eosinophilic granulocytes predominated (59%) with fewer large agranulocytes (27%) and basophilic granulocytes (13%). Small agranulocytes comprised 2% of the total population. Conclusions: No single treatment provided an optimal method to evaluate freshwater mussel hemolymph. Maximal hemocyte counts were obtained following formalin treatment. l ‐cysteine reduced clumping and maintained hemocyte morphology for performing a cytologic differential. These techniques provide a standardized approach for the hematologic evaluation of freshwater mussels.