翡翠贻贝的耐冷性

采用持续性降温(在海水中从)和突发性降温(在-1℃下的冷海水中冷处理1h)对翡翠贻贝进行冷处理,然后在室温下复苏,观察其复苏情况:采用持续性降温(在海水中,从21℃持续性降沮10h 9℃,从21℃持续性降沮18h 3℃)和突发性降沮(在-1.5℃、0℃、5℃、9℃的冷海水中冷处理10min)后进行冰藏,然后,每隔24h随机取出部分样品检定其存活情况,并观察其复苏情况,对翡翠贻贝的耐冷性进行了研究,结果证明翡翠贻贝具有较强的耐冷性,在≤0℃时,仍能存活,通过冰藏可达到保活保鲜之目的。     

A protocol for stocking hatchery reared freshwater pearl mussel Margaritifera margaritifera

• 1. Freshwater pearl mussel (Margaritifera margaritifera L.) populations are under serious threat of extinction throughout their geographical range and only a few remnant populations are recruiting to adulthood. Consequently, M. margaritifera is classified as endangered on the International Union for Conservation of Nature Red List.
• 2. Several institutions across many countries have set up Ark sites at hatcheries to culture and rear young M. margaritifera from population remnants, with the intention of stocking these juveniles into rivers. The release location must fulfill the habitat requirements for the full life‐cycle of the species, so they can contribute to the next generation and thus the long‐term recovery of the species. However, little research or advice exists about how to decide if river environments are suitable for stocking.
• 3. A protocol is presented for determining whether a M. margaritifera population will benefit from stocking hatchery reared juveniles and how to identify suitable areas. Stocking locations are considered from catchment scale to microscale using water quality (reach), macrohabitat (site) and microhabitat, including physicochemical properties of the substratum (spots).
• 4. A case study of the River Esk in north‐east England, is incorporated to exemplify the myriad of considerations surrounding attempts to conserve M. margaritifera, and describes how implementation of the protocol can structure and assist stocking programmes. Copyright © 2010 John Wiley & Sons, Ltd.

     

Meat Yield,Condition Index,and Biochemical Composition of Mussels (Mytilus galloprovincialis Lamarck, 1819) in Sinop,South of the Black Sea

Monthly variations in meat yield and biochemical composition of Mediterranean mussels on lantern nets were investigated from May 2005 to May 2006, in Sinop, south of the Black Sea. Dry weight condition index was between 2.66 and 7.10% with a mean of 4.86 ± 0.36%. Meat yield was maximum (26.69%) in March and minimum (17.43%) in October. Moisture values were between 78% (in June) and 86% (in April). Protein content in dry weight of mussels reached the highest value in February (74.64%) before the spawning time. Lipid value was maximum (18.03%) in May 2005.     

早期选择对三角帆蚌紫色选育品系幼蚌生长的影响

为了降低三角帆蚌良种选育过程中的工作量和加快选育进程,对三角帆蚌的早期选择效应进行了研究。通过对稚蚌的选择,考察了其对紫色选育品系幼蚌生长的影响。结果显示,选择组5 cm以上个体的比例达到65.20%,比对照组提高了26.80%,而4 cm以下个体下降了16.80%。通过进一步卡方检验(χ2=118.980,P0.01)表明,选择组与对照组的蚌体规格具有极显著差异。表明早期选择对三角帆蚌幼蚌的生长具有显著影响,早期选择效应显著。     

Effect of larval stocking density on growth,survival and whole body cortisol of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819) larvae reared under laboratory conditions

Interest of mussel hatchery development has increased during the last years as natural seed collection does not always satisfy the demand of producers. Success on larval bivalve culture depends on several factors such as diet, temperature or stocking density. In this study, the effect of larval density in mussel culture success has been assessed testing three larval densities: high (50 larvae mL^?1), medium (25 larvae mL^?1) and low (5 larvae mL^?1). Results showed higher growth and survival at low density but the amount of postlarvae was low. The highest number of settled larvae was observed at high density but mortality was also high and a delay on the larval development was detected producing a prolongation on the culture length. However, medium density resulted in a good survival and growth and also in a considerable amount of postlarvae, as this density could be adequate for massive mussel seed production. Cortisol content on the larvae and postlarvae was also analysed and significant differences were obtained among groups probably due to the stress associated to settlement and metamorphosis.     

Rediscovery of the largest population of the freshwater pearl mussel (Margaritifera margaritifera) in the Leningrad oblast (north‐west Russia)

• 1. An internationally important population of the freshwater pearl mussel (Margaritifera margaritifera) was rediscovered in a small river in north‐west Russia.
• 2. A survey of visible mussels in 2008/2009 indicated an estimated population of 40 000 individuals. This is the largest population currently known in the Leningrad oblast and is comparable with the entire pearl mussel population of some western European countries.
• 3. The average density of visible mussels was 29.6 individuals m^?2 in the middle part of the river. In the four largest mussel beds maximum densities of 1000+ individuals m^?2 were recorded. Such densities are exceptional and have not been reported elsewhere in Europe during the last 100 years.
• 4. Live juvenile mussels were recorded, indicating that that this population is viable, although further investigation is required to establish its status.
• 5. Analysis of the population age structure, based on the measurement of empty shells, showed an age class distribution similar to those reported for other healthy Margaritifera populations.
• 6. Only two live juveniles were found. However, this is likely to be due to the survey being restricted to counts of visible mussels only, and the age structure being based on the analysis of dead shells.
• 7. The population's current status and possible reasons for its survival in this river are discussed. Conservation measures should include the construction of a fish ladder to make fish migration through the culvert possible, removal of a metal screen preventing fish migration from the upper reaches of the river to the lake, reduction of recreation activities, and providing the local children's camp with water treatment facilities. Copyright © 2011 John Wiley & Sons, Ltd.

     

A critical reflection on the success of rearing and culturing juvenile freshwater mussels with a focus on the endangered freshwater pearl mussel (Margaritifera margaritifera L.)

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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.     

Growth of the fan mussel Pinna nobilis (Linnaeus, 1758) (Mollusca: Bivalvia) in experimental cages in the South Adriatic Sea

Juveniles of the fan mussel Pinna nobilis were collected in Mali Ston Bay from October to December 2006. Cages with juveniles were placed at three depths: 1, 3 and 5 m. At the end of a 2‐year growth period at 1 m depths, the average length was 244.1 ± 22.9 mm, at 3 m depths, specimens averaged 244.0 ± 25.3 mm, and at 5 m depths, the average length was 231.1 ± 22.5 mm. The average monthly growth of shell length for the total experimental period was 8.7 ± 5.3, 8.4 ± 4.5 and 7.6 ± 4.4 mm, at 1, 3 and 5 m depths respectively.