沼蛤(Limnoperna fortunei)幼虫的附着行为特性

沼蛤(Limnoperna fortunei Dunker,1857),俗称淡水壳菜,是一种扩散能力与适应能力都较强的入侵性底栖动物,它对自然环境与输水工程的侵入和大规模附着,不仅会破坏当地的生物群落结构,而且沼蛤成贝在工程内稳定附着后难以去除,造成重大工程危害。通过试验研究沼蛤幼虫的附着行为特性,并利用该特性对原水中的幼虫进行吸引附着处理,以减少幼虫进入工程造成污损附着。选用前期研究推荐的沼蛤幼虫喜好附着的黄麻材料制成的附着排作为试验材料,设置5组附着排长度工况:1,3,5,6,8 m,在5组流量工况:3.1,5.7,6.7,9.6,12.1 L/s下开展试验,研究不同附着排长度和流量条件下沼蛤幼虫的附着行为,以便优选出吸附幼虫的最佳条件。试验结果表明:(1)黄麻材料的吸附效果与附着排长度呈正相关关系,材料长度为3—5m时,吸附率即可达到50%;材料长度为6—8 m时,平均效果为62—76%,最佳吸附率可达93%;(2)流量过大会降低幼虫吸附效果,吸附也更不稳定;(3)幼虫发育先后经历D型幼虫、前期壳顶幼虫、后期壳顶幼虫、踯行期4个时期,吸附材料对后期壳顶和踯行期幼虫的吸附效果较前期壳顶幼虫更好;(4)附着材料密集布置于较短的长度内比稀疏布置于较长的长度内更有利于提高附着效果。     

Testing a molecular protocol to monitor the presence of golden mussel larvae (Limnoperna fortunei) in plankton samples

The golden mussel (Limnoperna fortunei, Mollusca: Mytilidae)is an emerging invasive species in freshwater environments inSouth America, causing extensive environmental and economicimpacts. A molecular method to detect larvae of the golden musselin plankton samples has been recently developed and holds promisefor becoming an important way to monitor the expansion of goldenmussel populations. In the present study, we conduct, for thefirst time, field tests of this method by comparing its performancewith alternative sampling efforts (microscopy and manual searchfor adults). In addition, we test different modifications ofthe molecular method to deal with PCR inhibition in environmentalsamples. The results indicate that the molecular method is veryefficient, being faster and more sensitive that microscopy methods.Therefore, the molecular method tested in the present studycan represent an invaluable tool in large-scale monitoring effortsof the golden mussel throughout its introduced range.     

Survival and attachment of biofouling freshwater mussel (Limnoperna fortunei) to environmental conditions: potential implications in its invasion,infection and biofouling control

Limnology - The golden mussel (Limnoperna fortunei) has caused worldwide problems for the eco-environment and man-made structures. There have been many control strategies proposed, which have...     

Molecular identification of larval bucephalids, Prosorhynchoides ozakii and Parabucephalopsis parasiluri , infecting the golden mussel, Limnoperna fortunei , by PCR-RFLP

A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was developed for the molecular identification of 2 introduced bucephalid trematodes, Prosorhynchoides ozakii and Parabucephalopsis parasiluri . The method was applied for sporocysts and cercariae obtained from the golden mussel Limnoperna fortunei collected in the Uji River, Japan. The PCR-RFLP method showed that L. fortunei is the intermediate host of both trematode species. The present study thus recognizes the risk of L. fortunei , an invasive molluscan species, as a potential host for pathogenic trematodes.     

Regional monitoring of freshwater pearl mussel <Emphasis Type="Italic">Margaritifera margaritifera</Emphasis> in the County of Norrbotten,Sweden

A total of 16 freshwater pearl mussel Margaritifera margaritifera rivers out of 64 known freshwater pearl mussel rivers are included in the Administrative County of Norrbotten regional monitoring program. First surveys were done in 1994 and the results show that only three rivers have viable populations according to national criteria despite little visible human impact and that juvenile mussels (<50 mm in length) have been found in all rivers at every occasion. The results also indicate that there might be “missing years” for juvenile recruitment suggesting that freshwater pearl mussel populations at the extreme end of the species range might be dependent on “golden moments” in order to keep up viable populations. Deeper knowledge and better tools for determining viable populations might be necessary in order to make the right decisions on how to manage the rivers and the freshwater pearl mussel populations.     

The invasive freshwater bivalve Limnoperna fortunei in South America: multiannual changes in its predation and effects on associated benthic invertebrates

Hydrobiologia - The invasive golden mussel Limnoperna fortunei is known to strongly affect benthic communities in South American freshwaters, but the evolution of these effects after the early...     

淡水入侵生物沼蛤的污损机制与防污措施研究进展

沼蛤是一种典型的淡水入侵贝类,能够利用其分泌的足丝牢固黏附在多种水下基质表面,引起严重的生物污损问题。沼蛤污损不但影响水生态系统健康,也给水利工程、交通运输、水产养殖等行业带来经济损失,已成为全球水生态系统安全和国民经济重要行业的潜在威胁,相关防污工作亟待开展。欲从根本上解决沼蛤污损问题,一方面需要加强对其基础生物学特性和污损机制的深入解析,另一方面也需要在此基础上研发更加经济、高效、环境友好的防污措施。本文综述了近年来国内外关于沼蛤污损生物学特性、污损机制和防污措施方面的研究进展,尤其是对沼蛤生物污损发生的主要机制如足探测识别、足丝黏附和环境影响等方面进行了总结,也从物理、化学、生物和防污材料等角度阐述了现有的沼蛤污损控制措施并对未来发展方向进行了展望,以期更加深入地理解沼蛤生物污损现象,为揭示其作用机制、制定科学有效的防污措施、维护水生态系统安全提供数据支撑,综述内容对于水下仿生材料研发也具有重要的参考价值。     

Potential Impact of Filter-feeding Invaders on Temperate Inland Freshwater Environments

Since the 1990s, biological invasions have captured the attention of the scientific community as an important element of global change and a major threat to biodiversity. The inland waters of South America provide two examples of biological invasions. This review examines bivalve invasions in South America, summarizes the research results for two species, the Asian clam (Corbicula fluminea) and the golden mussel (Limnoperna fortunei), and suggests further studies. The rapid expansion of invasive bivalves into these environments involves significant changes. Until now, C. fluminea, the Asian clam, did not produce generalized macrofouling in the Neotropical region, as is common in the Holarctic region. However, the first specific cases of macrofouling by C. fluminea were recently detected in heat interchangers of power stations in Brazil. On the other hand, L. fortunei is provoking new economic impacts in South American freshwaters through macrofouling. Before the invasion by the golden mussel, macrofouling was recorded only in the marine and estuarine environments of the Neotropical region. The impact caused by invasive bivalves in this region is not only economic, however. Rapid changes in the benthic community, favoring the presence of Oligochaeta and Hirudinea, as well as the displacement of native species of mollusks, are among the problems related to the presence of the golden mussel. Another issue is the settlement of golden mussels on native bivalves. This bivalve is now a new element in the diet of some native fish species, being the main food item in some cases.     

Ecosystem engineering impact of Limnoperna fortunei in South America

Limnoperna fortunei, or golden mussel, has invaded aquatic ecosystems in the Americas following it introduction from Southeast Asia. It is not only an aggressive invasive species, it is also a very effective ecosystem engineer, altering both ecosystem structure and function, and causes great ecological and economic impacts. This paper describes its impact as an ecosystem engineer (on benthic communities and the water column). A review of the existing scientific literature is presented, and the impact and the mechanisms by which the golden mussel modifies, maintains, and creates new environmental conditions in the invaded South American inland freshwater environments are analyzed. Understanding the ecosystem engineering roles of L. fortunei is important for its management and/or control in the invaded areas, and in cases of future invasions.     

A Spatial Modeling Approach to Predicting the Secondary Spread of Invasive Species Due to Ballast Water Discharge

Ballast water in ships is an important contributor to the secondary spread of invasive species in the Laurentian Great Lakes. Here, we use a model previously created to determine the role ballast water management has played in the secondary spread of viral hemorrhagic septicemia virus (VHSV) to identify the future spread of one current and two potential invasive species in the Great Lakes, the Eurasian Ruffe (Gymnocephalus cernuus), killer shrimp (Dikerogammarus villosus), and golden mussel (Limnoperna fortunei), respectively. Model predictions for Eurasian Ruffe have been used to direct surveillance efforts within the Great Lakes and DNA evidence of ruffe presence was recently reported from one of three high risk port localities identified by our model. Predictions made for killer shrimp and golden mussel suggest that these two species have the potential to become rapidly widespread if introduced to the Great Lakes, reinforcing the need for proactive ballast water management. The model used here is flexible enough to be applied to any species capable of being spread by ballast water in marine or freshwater ecosystems.     

Fibonacci,quasicrystals and the beauty of flowers

The appearance of Fibonacci sequences and the golden ratio in plant structures is one of the great outstanding puzzles of biology. Here I suggest that quasicrystals, which naturally pack in the golden ratio, may be ubiquitous in biological systems and introduce the golden ratio into plant phyllotaxy. The appearance of golden ratio-based structures as beautiful indicates that the golden ratio may play a role in the development of consciousness and lead to the aesthetic natural selection of flowering plants.     

Attachment strength of an adhesive nuisance mussel,limnoperna fortunei,against water flow

The attachment strength of the freshwater mussel Limnoperna fortunei against water flow was studied. Newton's expression successfully described the hydrodynamic drag force acting on the mussel with a drag coefficient value of 1.03. The drag‐resistant force (defined as hydrodynamic drag force at mussel detachment) was smaller than the detachment force measured using a tensile load test. A fairly good correlation was obtained between the drag‐resistant force and the number of secreted threads. The drag‐resistant force divided by the number of threads increased with shell size, suggesting that byssal thread strength increased with mussel growth. For the mussel specimens obtained from a water transmission pipe, thread width increased with shell size. However, thread width was not dependent on current velocity. There was no correlation between the number of secreted threads and shell length, which indicated that the number of secreted threads did not change with mussel size. Therefore, the water velocity needed to detach mussels increases with shell size of the mussel when the number of secreted threads is constant. The increases in the water velocity to detach mussels with larger shells suggests that the mussel becomes more resistant to water flow as it grows. It is estimated that a flow velocity of around lms^‐1 is critical for attachment/detachment of a juvenile mussel with a shell length of a few millimeters and one hundred byssal threads.     

Establishment of the zebra mussel,Dreissena polymorpha (Pallas), in the Neva Estuary (Gulf of Finland,Baltic Sea): distribution,population structure and possible impact on local unionid bivalves

Hydrobiologia - The zebra mussel, Dreissena polymorpha (Pallas), has invaded the Neva Estuary (eastern Gulf of Finland) by mid 1980s. In order to assess the current status of the zebra mussel...     

Evaluating the influence of land use,drought and reach isolation on the occurrence of freshwater mussel species in the lower Flint River Basin,Georgia (U.S.A.)

1. North American freshwater mussels have been subjected to multiple stressors in recent decades that have contributed to declines in the status and distribution of many species. However, considerable uncertainty exists regarding the relative influence of these factors on observed population declines. 2. We used an occupancy modelling approach to quantify relationships between mussel species occurrence and various site‐ and catchment‐level factors, including land cover, stream size, the occurrence of drought and reach isolation due to impoundment for 21 mussel species native to the lower Flint River Basin, Georgia, U.S.A. 3. Our modelling approach accounted for potential biases associated with both incomplete detection and misidentification of species, which are frequently not accommodated as sources of bias in freshwater mussel studies. 4. Modelling results suggested that mussel species were, on average, four times less likely to be present following severe drought, but the negative effects of drought declined rapidly with increasing stream size. Similarly, mussel species were 15 times less likely to occupy small streams that were isolated from mainstem tributaries by impoundments. 5. This study provides insight into the effects of natural and anthropogenic factors on freshwater mussel species. Our findings add to a growing body of literature aimed at improving understanding of the predominant factors influencing freshwater mussel populations and fostering the development of more informed and effective conservation strategies.     

Partial replacement of fishmeal in diets for turbot (Scophthalmus maximus,Linnaeus, 1758) culture using blue mussel (Mytilus edulis,Linneus, 1758) meat

The purpose of this study was to investigate whether meat from blue mussels (Mytilus edulis) harvested from offshore structures could be used as an alternative protein source in aquaculture fish feed for turbot (Scophthalmus maximus). Two feeding experiments with turbot were conducted in an initial experiment to test the applicability of mussel meal as a fishmeal replacement and/or supplement in turbot feed. In experiment A, the welfare, acceptance, and digestibility of feedstuff with 100%, 50% and 0% of mussel meal replacement for the fishmeal were tested for 8 weeks. In experiment B that followed, the convenience ratio of mussel meal protein in turbot feed for optimum growth was examined. Feedstuff with 25%, 10% and 0% of mussel meal were also fed for 8 (+6) weeks. Growth rates of fish were measured every 2 weeks and their health condition (liver somatic index) determined at the beginning and end of the experiments. Experiment A revealed that a replacement of fishmeal with either 100% or 50% mussel meal resulted in depressed growth (SGR: 1.31 ± 0.04 with 100% mussel meal; 1.54 ± 0.04 with 50% mussel meal; 1.71 ± 0.07 with 0% mussel meal). Experiment B revealed that a fishmeal replacement with 10% or 25% of mussel meal did not reduce growth nor did it have a negative effect on the health of the tested turbot. The study revealed that mussel meal has a high potential to serve as a supplement or as a fishmeal replacement in feed for turbot raised in aquaculture systems. Thus, its use in commercial aquaculture should be given future consideration.     

Zebra mussel adhesion: structure of the byssal adhesive apparatus in the freshwater mussel, Dreissena polymorpha

The freshwater zebra mussel (Dreissena polymorpha) owes a large part of its success as an invasive species to its ability to attach to a wide variety of substrates. As in marine mussels, this attachment is achieved by a proteinaceous byssus, a series of threads joined at a stem that connect the mussel to adhesive plaques secreted onto the substrate. Although the zebra mussel byssus is superficially similar to marine mussels, significant structural and compositional differences suggest that further investigation of the adhesion mechanisms in this freshwater species is warranted. Here we present an ultrastructural examination of the zebra mussel byssus, with emphasis on interfaces that are critical to its adhesive function. By examining the attached plaques, we show that adhesion is mediated by a uniform electron dense layer on the underside of the plaque. This layer is only 10-20 nm thick and makes direct and continuous contact with the substrate. The plaque itself is fibrous, and curiously can exhibit either a dense or porous morphology. In zebra mussels, a graded interface between the animal and the substrate mussels is achieved by interdigitation of uniform threads with the stem, in contrast to marine mussels, where the threads themselves are non-uniform. Our observations of several novel aspects of zebra mussel byssal ultrastructure may have important implications not only for preventing biofouling by the zebra mussel, but for the development of new bioadhesives as well.     

The incidence of the Pea crab, Pinnotheres pisum in the two types of Mytilus (Mollusca: Bivalvia) from Padstow, south-west England

Significant differences in the infection of M. edulis and the "Padstow type" mussel with P. pisum are recorded, and some possible explanations for these differences are discussed.
Both types of Mytilus from the mid and lower regions of the mussel bed showed heavier infections than mussels higher on the shore. Even so, the differences between the two types were still maintained.
A relationship exists between crab and mussel size, larger crabs being found only in larger hosts. The smallest mussel found to be infected with Pinnotheres measured 3·35 cm in length.
Infection in M. edulis was found to increase with increased size of host, the largest occurring mussels having from 80 to 100% infection. Larger mussels occurred in greater numbers in the low shore. It is assumed that infection in the "Padstow type" would show a similar relationship if sufficient recordings had been available.
The presence of the crab causes gill damage, and infected mussels show considerably lower tissue weights and slightly greater shell weights than uninfected mussels of similar size.
The presence of the crab does not appear to influence the reproductive capacity of the mussel.     

Spatial patterns of growth in the mussel, Mytilus californianus, across a major oceanographic and biogeographic boundary at Point Conception, California, USA

The Point Conception, California, USA region (hereafter PC) is one of the most important biogeographic and oceanographic discontinuities on the US west coast. Here we address how mesoscale oceanographic variability in the region around PC affects the growth of the competitively dominant species in the rocky intertidal assemblage: the mussel Mytilus californianus. Strong upwelling and high wave exposure dominate the California coast north of PC, and weak, seasonal upwelling and warmer water temperatures are characteristic of the region south/east of PC. We hypothesized that the oceanographic gradients in temperature, upwelling, wave exposure and productivity around PC would exert strong bottom–up influences on growth rates of mussels, potentially underlying large-scale differences in community structure around the PC region. We evaluated these predictions by measuring mussel growth rates across the PC region both in the intertidal and offshore on moorings. Intertidal mussels grew at much higher rates at sites south relative to north of PC and growth rates decreased in a gradient from south to north. The gradient in intertidal mussel growth around PC was uncorrelated with inshore concentrations of chlorophyll-a, and was most strongly correlated with the alongshore gradient in wave exposure and intertidal temperature. Mussels on moorings offshore from the intertidal sites grew at much higher rates than those in the corresponding intertidal areas, and mussel growth rates did not differ significantly among moored locations around PC. The gradient of increasing temperature from north to south among mooring sites was correlated with a decreasing gradient in productivity in the same direction, potentially contributing to equal and opposite effects on mussel growth at offshore moorings. This study suggests that environmental factors such as cold temperatures and high wave exposure contribute to the spatial pattern of decreasing mussel growth rates from south to north around PC, underlying large-scale patterns of community structure in this region.     

Documentation of sites of intertidal blue mussel (Mytilus edulis L.) beds of the Lower Saxonian Wadden Sea, southern North Sea (as of 2003) and the role of their structure for spatfall settlement

Field surveys (dating back to 1950) and aerial photograph series (dating back to 1966) were evaluated to determine sites of intertidal blue mussel (Mytilus edulis) beds at the Wadden Sea coast of Lower Saxony. Maps were prepared indicating sites of blue mussel beds during the last decades. A table gives additional information on the presence (or absence) of blue mussel beds at each site at the time of large-scale surveys. Altogether 187 sites of M. edulis beds were recorded in the investigation area. In spring 1996, there were still only 19 sites where mussel beds still occurred, although at 51 sites residual mussel-bed structures were present, e.g. shell bases of former beds or protruding patches (which had been occupied by M. edulis before the beds vanished) and open spaces. At that time, the majority of the sites contained neither mussel beds nor mussel-bed structures. The analysis of recent data confirmed that mussel larvae have preferred to settle in sites of present mussel beds and sites with bases of former mussel beds. There was no preferential selection of one of these categories (settled beds vs. shell bases). On the other hand, the presence of mussel beds or mussel bed structures is not obligatory for settlement, because sites without those structures were also re-settled by the spatfall in 1996, even though on a smaller scale.     

Effects of Total Soft Tissue and Shell Thickness on the Accumulation of Heavy Metals (Cd,Cu, Pb,and Zn) in the Green-Lipped Mussel Perna viridis

The effects of the total soft tissue dry weight and shell thickness and on the accumulation of Cd, Cu, Pb, and Zn were determined in the green-lipped mussel Perna viridis. In agreement with Boyden's formula (1977), our results showed that the plotting of metal concentrations against the total soft tissue dry weight and shell thickness of the mussel on a double logarithmic basis gave negative coefficients especially for Cd, Pb, and Zn. Therefore, the smaller mussels (lower total soft tissue dry weight) had higher concentrations of Cd, Pb, and Zn than the larger ones. Since shell thickness could be considered to estimate of the age of the mussel, it was also found that the younger mussels accumulated more Cd, Pb, and Zn than the older ones. This indicated that P. viridis has a different metabolic strategy for each of the metals studied which may be related to age. However, the accumulation of Cu was hardly affected by the sizes and ages of the mussel. This indicated that the accumulation pathways of Cu and the processes affecting the bioavailability of Cu to the mussel are different from those for Cd, Pb, and Zn.