1、Designation:E245506(Reapproved 2013)Standard Guide forConducting Laboratory Toxicity Tests with FreshwaterMussels1This standard is issued under the fixed designation E2455;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of l
2、ast revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This standard guide describes methods for conductinglaboratory toxicity tests with early life stages of freshwatermussels in
3、cluding glochidia and juvenile mussels in water-onlyexposures(Annex A1).Future revisions to this standard maydescribe methods for conducting toxicity tests with(1)adultfreshwater mussels and(2)contaminated sediments usingvarious life stages of freshwater mussels.1.2 Many factors are cited as potenti
4、ally contributing to thedecline of freshwater mussel populations in NorthAmerica.Ofthe nearly 300 taxa of freshwater mussels in NorthAmerica,70species(23%)are listed as endangered or threatened andanother 40 species(14%)are candidates for possible listing(Williams et al 1993(1);Neves 1997,2004(2,3).
5、2Habitatalteration,introduction of exotic species,over-utilization,disease,predation and pollution are considered causal orcontributing factors in many areas of the United States(Neveset al 1997)(4).Over the past decade,there have been over 75published studies conducted that have evaluated the role
6、ofcontaminants in the decline of populations of freshwatermussels(Kernaghan et al 2005)(5).In these studies,early lifestages of mussels of several species are highly sensitive tosome metals and ammonia in water exposures when comparedto many of the most sensitive species of other invertebrates,fish,
7、or amphibians that are commonly used to establish U.S.Environmental Protection Agency Water Quality Criteria(WQC;Augspurger et al 2003(6),Keller et al 2005(7),Kernaghan et al 2005(5);USGS(2005a,b)(8,9)section 1.5).Importantly,results of these previous studies indicate WQC forindividual chemicals est
8、ablished for the protection of aquaticorganisms may not be adequately protective of sensitive stagesof freshwater mussels.1.3 Summary of Life History of Freshwater Mussels:1.3.1 Freshwater mussels are bivalve mollusks belonging tothe family Unionidae or Margaritiferidae(section 10.1).Adultsare seden
9、tary animals,spending their entire lives partially orcompletely burrowed in the bottoms of streams,rivers,orlakes.Adult mussels are filter feeders,using their gills toremove suspended particles from the water column.Themicroscopic,juvenile stage uses foot(pedal)feeding to somedegree for the first se
10、veral months of their lives,feeding ondepositional materials in pore water of sediment,includingbacteria,algae,and detritus.Freshwater mussels have anunusual and complex mode of reproduction,which includes abrief,obligatory parasitic stage on fish or other host organismscalled glochidia(Fig.1).1.3.2
11、 The successful transfer of mature glochidia to asuitable host constitutes a critical event in the life cycle of mostfreshwater mussels.Once the glochidia are released from thefemale,the glochidia need to attach to the gills or the fins of anappropriate fish host and encyst to complete development.A
12、lthough glochidia may survive for months during brooding inthe female mussel,glochidia typically survive for only a fewdays after release unless the glochidia reach a compatible host.Encystment on the host occurs by overgrowth of host tissue.Metamorphosis of juvenile mussels on the fish host occursw
13、ithin days or weeks,depending on species and temperature.Host fish specificity varies among mussels.While some musselspecies appear to require a single host organism,other speciescan transform their glochidia into juvenile mussels on severalspecies of host fish.Following proper host infestation,gloc
14、hidia transform into microscopic juveniles and excyst(drop off)and settle into suitable habitat to survive.Thetransformation of glochidia to juveniles results in the develop-ment of internal organs necessary for self-sustained existenceas a benthic organism.1.3.3 Newly-transformed juvenile mussels h
15、ave a life styledifferent from adult mussels.Transformed juvenile musselsmay be at the sediment-water interface or may burrow severalcentimeters into sediment and rely on water percolating be-tween substrate particles of sediment for food and oxygen.Newly-transformed juvenile mussels feed using cili
16、ary currents1This guide is under the jurisdiction ofASTM Committee E50 on EnvironmentalAssessment,Risk Management and Corrective Action and is the direct responsibil-ity of Subcommittee E50.47 on Biological Effects and Environmental Fate.Current edition approved March 1,2013 Published May 2013.Originallyapproved in 2005.Last previous edition approved in 2006 as E2455-06.DOI:10.1520/E2455-06R13.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyrig
