河南丽蚌属淡水软体动物研究

共记述河南省的丽蚌属12种,其中天津丽蚌Lamprotula tientsinensis（Crosse＆Debeaux,1863）为河南新记录,并编制了这些种类的检索表。     

Morphometric relationship of weight and size of cultured freshwater pearl mussel, Hyriopsis (Limnoscapha) myersiana, under laboratory conditions and earthen pond phases

The freshwater pearl mussel, Hyriopsis (Limnoscapha) myersiana (Lea, 1856), was cultured in the laboratory (0–120 days old), in an earthen pond in acrylic containers (120–270 days old) and in pocket nets with frames (270–360 days old). Measurements were taken of the length–height and the total body weight–size (shell length, shell height and shell width). It was found that the length–height in each period of culture showed a linear relationship and that the shell height increased as the shell length increased, along with the same linear relationship. When statistical analyses were performed, this linear regression line consisted of three distinct lines (P < 0.01). The general morphometric relationships between the length and height of mussels grown in the laboratory, in acrylic containers and in pocket nets were Log H = −0.147 + 0.828Log L, Log H = −0.211 + 0.909Log L and Log H = −0.264 + 0.951Log L, respectively. The relationship between the total body weight–size in different culture phases was a positive allometric equation and the two curved lines were not the same (P < 0.01). The general morphometric relationships between the length and the total body weight of the mussels cultured in acrylic containers and pocket nets were Log W = −3.747 + 2.674Log L and Log W = −4.149 + 2.976Log L, respectively. Such measurements are useful in the management of different culture phases of H. (L.) myersiana.     

Digestive enzymes and in-vitro digestibility of different species of phytoplankton for culture of the freshwater pearl mussel, <Emphasis Type="Italic">Hyriopsis</Emphasis> (<Emphasis Type="Italic">Hyriopsis</Emphasis>) <Emphasis Type="Italic">bialatus</Emphasis>

Hyriopsis (Hyriopsis) bialatus has been cultured during the mussel life cycle from glochidia to the adult stage with a low total survival of 6% up to 130-day-old juveniles. The main digestive enzymes (amylase and proteinases) were not detectable in one-day-old juveniles, and increased during development. The stomach, including digestive glands, was the major digestive organ for both carbohydrate and protein. The optimum conditions for amylase activity were 40°C and pH 7; for acidic proteinases they were 60°C and pH 5. Two main alkaline proteinases were found in the intestine, with optimum conditions of 30°C and pH 8 and 60°C and pH 8. To improve mussel survival by finding suitable phytoplankton species and age as food for juveniles and adults, an in-vitro digestibility test was performed on ten algal species three and seven days old using amylase and proteinases in crude enzyme extracts from different mussel life stages. Among the phytoplankton selected, the three most efficiently digested by juveniles were seven-day-old Chlorella sp.2, seven-day-old Chlorococcum sp. and seven-day-old Kirchneriella incurvata, in the ratio 1:1:3 for 30-day-old juveniles and 3:1:1 for 130-day-old juveniles. For the adult mussel, three-day-old Chlorella sp.2, seven-day-old Coccomyxa sp., and seven-day-old Monoraphidium sp., in the ratio 3:1:1, were the most digestible phytoplankton. Levels of in-vitro digestibility were related to the quality (not the concentrations) of carbohydrate and protein in the phytoplankton mixtures, and protein digestibility seemed to be the key factor determining food quality for the mussel.     

Risk assessment of parasitic/symbiotic organisms of the commercially important mytilid Modiolus barbatus (Linnaeus, 1758)

A parasitological survey of the edible and commercially valuable mytilid horse‐bearded mussel (Modiolus barbatus Linnaeus, 1758) was carried out in the Mali Ston Bay, Adriatic Sea, in 2004 and 2005 to assess the potential effects of parasites/symbionts on this bivalve population. Data sets of abundance and prevalence were used to evaluate the structure and dynamics of infracommunities and component parasitic/symbiotic communities, along with evaluated histopathological changes, to assess the overall risk that these organisms pose to the mytilid. Based on moderate diversity indices and expected seasonal oscillation between the values of prevalence/abundance, parasitic/symbiotic fauna of M. barbatus was shown to be relatively stable, although moderately impoverished assemblages, dominated by two species, turbellarian Paravortex cardii and gregarine Nematopsis sp. Histopathological changes indicated only three species as pathogenic –Gymnophallus sp. sporocysts, Nematopsis sp. and a haplosporidian, although their pathological risk was assessed to be very low or low. From the epizootiological point of view, parasites are not a limiting factor for the successful introduction and farming of the M. barbatus.     

Diversity,habitat use and conservation of freshwater molluscs in the lower Guadiana River basin (SW Iberian Peninsula)

• 1. A study on the distribution pattern and conservation of freshwater molluscs of the south Guadiana River (SW Iberian Peninsula) was carried out between the Alqueva dam and the Atlantic Ocean.
• 2. The knowledge of the distribution and abundance of molluscs before the closure of the Alqueva dam is an important tool for evaluating the potential reduction in diversity and the changes in species conservation status that may occur later.
• 3. Twenty‐three species (15 gastropods and 8 bivalves) were found in the study area. The presence of Unio crassus and Potomida littoralis indicates the importance of this basin for the conservation of endangered mussels (Unionidae) in the south Iberian Peninsula.
• 4. Drainage area above the sampling site explained almost 58% of the variation in species richness. Larger drainage areas had a higher number of species, including those endemic to the basin.
• 5. Patterns of habitat use were examined to identify species preferences with respect to the erosional‐depositional gradient. Islamia minuta, Pisidium casertanum and Pisidium personatum find their optimum habitat in headwaters, whereas Theodoxus fluviatilis, Mercuria emiliana, Radix auricularia and all unionid species inhabit large and stable habitats downstream without marine influence.
• 6. Populations of invasive Corbicula fluminea were found in the Guadiana River basin, both in rivers with large drainage areas and in brackish waters near the mouths of rivers.

Copyright © 2006 John Wiley & Sons, Ltd.     

Freshwater mollusc assemblages and habitat associations in the Danube River drainage,Hungary

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Invasive gobies in the Danube: invasion success facilitated by availability and selection of superior food resources

Abstract –  We investigated somatic condition, growth rate, diet and food resources of the native (lower Danube) and non-native (upper Danube) populations of invasive bighead goby Neogobius kessleri and round goby N. melanostomus within the Danube River to answer the question whether prey availability and type may have facilitated successful goby invasion to the upper Danube. The non-native populations of both species were in better somatic condition and grew faster. The biomass of nonmollusc macrozoobenthos, dominated by Amphipoda, was markedly higher in the non-native range while molluscs were recorded frequently in both the native and non-native ranges. Amphipods were far the most consumed prey by non-native fish, whereas native fish combined two main prey types – amphipods and fish (bighead goby) and amphipods and bivalves (round goby). A laboratory experiment was conducted to reveal whether the low consumption of bivalves by the round goby in the non-native range reflects prey encounter rates or alternatively prey selectivity. When bivalves and amphipods were offered simultaneously in excess to the experimental fish, round goby showed strong preference towards amphipods. Molluscs are hypothesised to be an alternative rather than the most preferred prey for the round goby. Rich food resources utilised by the non-native bighead and round goby contribute to their invasive success in the upper Danube.