jaecied infectioa levels ai a mean grade of 4.9. It ma> take sev eral yeais for a turnover 

 of aqoatic insect communities to occur, or peibaps T. tubifex numbers have been reduced, 

 bat nombeis are qgi«ififa«it enou^ to saf^oti the comimwiion of the disease life cvcle. 



Recent studies provide evidence to support tfae idea that elevmed densities of T. 

 ttA^iac are not necessai>" to cause high infection levels in winrling disease positive 

 streams. For example, a stud>' on tfae Madison River found low denaties of T. tubtfex can 

 still produce sufiOcient TANts to be higfah infecth e to trout (ICrueger 2002). In tfae \jppei: 

 Cokxado River basin, T. tubifex w^as found to be wide^jread, bin fluctuated in abundance 

 dHDi^ioat ales, suggesting diere are point sources of 3£ cerebralis infection (Zendt and 

 Bexgezsen 2000). As snggFsted, individoal sources xoojf not be agnificant, but tfae 

 arflective efifect of these liot spots' could lead to faigfa levels of infection in a stream. 

 The presence and daisit> of T. tubifex vi~as not tfae nK>st imptxtant indicator of infection 

 sevexiiy in a study on Moiasma spring oeeks ( .\ndason 2004), irMtifsmng a combination 

 of tnbffidd matuify, suitd^e habitat to suppwt T. tubifex, and an nqnit of virile M. 

 cerebralis spores (Matkiw 19S6) vosss be a betta ptB&cux of infection severity. There 

 a|ipea^ to be consensus that sediment and nuiriait enridment fosto^ tfae development of 

 dmndant T. tubifex pc^iulatims, but due to tfae \^et> of coikliticns that T. tubifex 

 "-;h2Ht. hatmat does not qipear to be tfae limiting factor. Restoration work nia> in fact be 

 i=cre:2Lsiiig T. tubifex h^Htat, but pafaaps tfaere are limited areas witfain a stream capable 

 3-r: - -g tfae wxxm in significant abundance to support tfae wfairiing disease life 

 . - r 7. - -je effects (if an» of habitat restcsati<»i cm whirling disease sev erit> may take 

 se% era! years of monilmiii^ to be detected. 



Recent teseardi into the ecolog:- ::" hir -i 15 rise h^i ?r? ide^: r.r- 

 infixmadon pertinent to tfae monitoring ar: ~^.^-^z-z--. r. : -^ -..iz-iz r -; 



Blackfijot Waierafaed. Recent Indies s.: r^t. :- i: ~-::. 



ttai^KUtDtes ranges than pieviuusty idennrit 1 -s.iz: — - r.^.- __>„r-^, '•' ".i-'j. 

 State Umvasity. personal axmnunication 1-j;: : ...^ r "e -'=^^ ^ere -_^-c -: 

 haupeiai nres ransins from 43 to 53.6 ^ =."i " :-i.~r t; ."" trs y. -5 5 - 53.6 7. ^--- ii 

 low as 33.8 7 -_:;' .-. 2004). Al"_-:-^'. r.~:t:i:-::i ::--: - ;:"-'2 creeks were 

 fawxabie fc: ::-.-- 7A'' -elt^it ss., - _ r 7. -^ i~ : ri: -und, this 

 oocoaence V. ^. -.;: ir:;.;: 7-.; ;:-; ,:: i-^: _c__ -i. .it; ::.:;:;.:.:- in spring 

 creeks may :•-.-/ - :t:-- 1^-: ;: ^ ::-. 7. :: ~i, -'^-.^-" :: :r~rcri:-^r5 ii r:r.:ously 



described ir. -^ r-r: -^ :^r-.r': 7-i^^: :-ir ^:r:.:- ^ =-=^^ iricdy 



depaidentcr - - .. 1.--. : :t-.:-;-i:--;3 sn -. .j-'^rs in infections ma>- result 

 fiomanacc— ~. - i ' ::v":.:i :_:; _r.:s -_". :icr>on l.r^^,i. 



A rt-;r- ; . : . it. . r ; i : ;::r— : infection timing unique to spring creeks, 

 compare: - - r" - . „ t - A_- ler;:- 2004j. The seasonal c>cle of A£ 



cerebra.. .t r-.t: - .- t 7- - : ^; : :---g creeks followed a pattern wiiere 

 infection was highest in winter and ear. srrr.. ::.:eased to low levels during summez, 

 and then increased again in late &11. 7' -_ i*h late Mav aiKi late June peaks 



observed in a rec^it stud>' in tfae \lad:i ' ^ .: 7 - - _ et al. 2002) and witfa a study in 

 tfae Colorado River wiiere triactinoir --e at tfaeir highest doisity 



dorai^ June tfaiougfa September (Th : . . -_ 1 .0). The lack of overlap 



between infection tinm^ and emerge- . r r - . -^Jibow trout fry suggested 



spring-spawning trout would be at lo-. r._.'. .; .rjt^u..'^ ==.- :.i spring creeks v*ith high 



96 



