Effects of pesticides on embryonic development of clams and oysters and on survival and growth of the larvae

Fifty-two compounds were tested for their effects on embryos of the hard clam, Mercenaria mercenaria, and the American oyster, Crassostrea 1Jirginica, and on their larvae. The pesticides included 17 insecticides, 12 herbicides, one nematocide, four solvents, and 18 miscellaneous bactericides, fungicides, and algicides. Most of the compounds affected embryonic development more than survival or growth of larvae. Some, however, drastically reduced growth of larvae at conThe extensive use in ree-ent, yenrs of highly persistent pesti('ides for eontrol of certitin insects n.nd undesintble phtnts, not only on ngric.lllt'llral bnds but nlso on reerelttionnl iU"eltS, bkes, streilms, and mnrshes, hiLs mnde impernti\ce nn evnluntion of the effec.ts of t,hese e-ompounds on fish and wildlife. The eventual gOll.! is to eontrol undesimble spedes, with the lenst hnrm to the desimhle members of the ecosyst,em. Att,nillll1ent of this gOltl req'.tires extensi\ce knowledge of how eltch pest,idde nffects eltch speejes or representltt,ive speeies of the system. Also, the pestieide must be highly spe('ifie 01' be n.pplied so thn.t its dispersion is strict.ly limited. Pestieides mlty enter the hnbitnt of shellfish in several Wl\YS. One is by being enrried there in l'llllOff wMer from trented ! nnd ltrens. CottniH (1960) st,iLted tllil.t, :3 to 3 billion pounds (9.07 to 13.61 x lOs kg.) of pestieides iLre used lLnnuit.lly in the United Sttttes on nbout 100 million neres (40.5 x lOG hIt.) of bnd. Thil1111-l1ll (1964) stltted thnt the United Stntes used 175,000 short tons (158,760 metric. tons) of inseet.ieides in 1962 and about hnlf that muc.h of fungicides nnd herbicides. I Pl"I. 'SI:llt ~lddn~ss: l~l1in:'rsity of . i\-Illl"yland. Natura] Rl"! 'soUl'c~s Institutt'. Box 38. Solol11ons. ~hl. ~1)688. 1-'ulllisl"u. '. 1 . :\ prill~II.1. :I. FISHE n y BljLLE1~IN: YOLo 67, NO. ~ centrations that had relatively little effect on embryonic development. It is necessary, therefore, to evaluate the effects of pesticides on all stages of the life cycle of an organism befQre the pesticide can be considered safe. Nevertheless, differences in toxicity to bivalve larvae among compounds of each category of pesticide are large enough that it should be possible to select compounds to control pest species without serious damage to commercial shellfish. Doudoroff, Knt.l<:, and Tnrl<:well (1953) Il1nde Inbomtory tests of soils eolleeted fl'om t.oxrLphenetreltted fields and eondudell thnt st,renll1 wltt.ers cnn be made t.oxie t.o fish by the drainnge from sueh fields. 8ueh runoff water may ('1tl'I'Y the pestiddes in sol.ution, adsorbed on suspended pm·tides, or ineorpomt.ed in plit.n ts a.nd tLnil11ills in. the WI1.t.er. Certainly, In.rge qUl1.ntit,ies of the vesticides thnt lerLch from the soil must eventunlly reiLch constnl marine wiLters and sediments. A seeond, more direet" nnll perhltps more ensily regubted method by which pestic.ides I11ny enter the estuarine environment, is the use of inseeticides ltnd herbieides on slth lllnrshes and estUluies to eont,rol mosquitoes ll.nd undesimble plants. In some regions lit.rge areItS nre slH"nyed neit.1' shellfish beds. Pestieides used in this wny probltbly erent,e higher concentmtions of the ltetive ingredients in the estunrine \Htter thltn nre nehieved hy nny other method. LooslLnoff, ~/IltcKenzie, 111111 Shearer (1959 ), Loosnlloff et It. (1960), nnd LOOSil.noff (1961) proposed the lise of se\"eral pesticides for (,he eontrol of eertll.in predators lmd eompet,itors of ::: LoosnnoJT, v, L., C. L. i\'Ial'K('nzil! , JI'" and L. W. Shean'}', Inf.! I. PSI) of chl~mical bnr}'il~rs to ]l1"(,h'cl slll. 'lIl1s.h hl'll~ fl'0111 PI·Cthltors. Bul'. Cnmlllt:I·. Fish. BioI. Lab . Milford. (',mil. , Bull. I. ;, 23: 1-11.