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<br />
<br />det'per parts uf [he habitat. \X'hen tt.ady, J female
<br />tntt'rs the territory 01.1 male (0 spawn on the
<br />substrOltc, Tht, m.dt's in;ldveHenrl}". although
<br />cffectlvdr. pr(ltt'(t the e~.gs wnh their Jf"l.:rr:SSl\-'C
<br />territorial bt'hJ,\llH. Young art'" ~cnl:rJ,ll~. Ignored. S,)
<br />they move and feed rht!)ughuut the mOlle's [errH\lry
<br />with Impunity Growth IS rapid. .Ino yount< hatl:hed
<br />In early sprin~ can m,nure and rept!)duce In
<br />mid.summer
<br />~fost fishes Jr-posit their l'l',CS Outside rhe It'nuk-'s
<br />body. Tormlnnows. howt'\"er, pr,l(tlce IntNnJ.l
<br />fcrtillzJ.tJon J.nJ Jnclormt"nt of young Spt'rm
<br />packets (spt'rm.ltophllresl are ddl\"en:J to [he
<br />female.s genitJ.I openin!( hy us/: of a highly mlldlfil',j
<br />.In,11 fin of tht' malt:. A femalt can stllre sperm. so .1
<br />Single sex ,1([ (J.n St'rv/: to fCHdize r-~s thrllughout
<br />her lift',
<br />Topmlnnows In the lowermost RIO Y;Il,.-1UI Include
<br />ont' kind rbat dltlr-rs r-vcn more m.lrkeJly from most
<br />mher Ilshes In HS mtlde of reproJuulOn. Most
<br />wpmlnnows .ltt. bisexual: mol It's J.nd l~males hrt'td
<br />normally. Somt', htlwe\cr. hJ'.e deHloped systems
<br />where m.des do nor t.XISL Ft'm,dcs hrt'r-J with
<br />i1nmher kind of rorminnov. m;lle. produung J,ll
<br />female offsprlll,l: uf hybnd ongln. The w,IY rhls
<br />systt'm uperatts remainS poorly umkrstolld. In ,In~.
<br />case, young de,'dop within the (em.l!e's O\,ItICS (fig
<br />5.1) to a l.uge SIl{' (up to 10 mm [!Hal length). Jnd
<br />can s.....im. ft,td. ;\nJ J'.\)IJ pted.lwrs a fr-v. ~t'nlOds
<br />Jfter birth. As WIth pupfish. St'XUJI mawr,\tIon IS
<br />rapid. SOmetlml'S It.ss th.ln SIX wetb ;Iher birth In
<br />warm W.Her In summr-r
<br />
<br />Low Desert Strea01S
<br />
<br />,\Iost low dt'scrt srrt'J,ms .Ire nllW dl\.er[eJ hy d,lms
<br />In their he;idw.lters, or h,I\T their SUbtl.rr.lne<ln
<br />surpliei> Intt'rdlnt'd /1~' well fidds that pump tht'm
<br />dry. Pumra.L:{' tllr IrtlF;Hion .lnd other USt'S Ius.
<br />lowen-d water tJhln m\lre [h,in 50 m In most VJlIt."~'s
<br />and more th.m 200 m In s\)me. .IOJ bt.heJdlnF of
<br />sttr-ams hy imp\)unJmem In montane pMtS ot' the
<br />watersh~'ds pren'ms Jqulfer rc'chMFe. OnJ~. streJms
<br />with reli,lble sprin~ Inflows H"maln hdow (,00 m.
<br />JnJ many 01 these no lonFer fluw excer[ thhlUgh
<br />manmaue delivcry ch,innds \\'here rht'\. do. such JS
<br />In and bt:lo\\ the GrJnJ C;inpm. humans Jrl' slmpl~.
<br />uSing che n;uur,ll channels tor water dehn-f1es from
<br />upstream reSfn'OIfS Tht. pr~'sent st'(tl(ln is therefore
<br />largely a uesdlPtWn of the past. J reconstruction 01
<br />an ori~in,ll sclte th.lt m3~. never be rt"creJted. s,.'me
<br />nJUn' Ilshes rl:rSIS[ In rht, mainstreams, hut only In
<br />speCIal pl.1ct's.
<br />Alllar,l:e ri..-ers of the regIOn are (or lus[()f1(Jlly
<br />wt"re) chJfacteclZed hy hlF:h runoff from spring Jod
<br />
<br />
<br />Figure 54 Near'lerm embryos In a lemale Gila
<br />lopminnowlcharalito de Gila (40 mm m lotal lenglh) lrom
<br />Monkey Sprmg. Anzona
<br />
<br />early summe:r snowmdt In Jlst;lm mOUm;iInS, Jnu d
<br />stcond perinJ of lc'sstr n(hlulng during summer
<br />rJ,lI\s. Prmr ro man'.. moudiLltions, the Colorado
<br />River neM Yuma IlunuJteJ In volumt. ffllm less
<br />[h.Ln 0.35 to more than -~UO cubiC mt'tt'rs pt'r
<br />'r-conu.
<br />All thtsr- srre.ims /low a..:ross gt"i)logic Structure. At
<br />It.lSt In I-'Mt. .lnd thus altt'rnJtl.'ly P;lSS rhrouFh bro..ld
<br />,dlu\.I;lted valkys and nJrrllW FllrgtS (Fig. 41. Valleys
<br />represent dowmhrow blocks, J.nu ..:anyons ;He Cut
<br />through upilfted blocks that cllmpnst" the northeast.
<br />SlludlWcSt-Orlemed m\)Untaln ran,c:es of the region.
<br />\\',Her taroles in \'alleys, t'\'l'n In [he h()[tcs[ parts of
<br />the S\lnoran Desert. were within J. rev. fet't uf [he
<br />surfan: I'rlllr [l) human Jltt.ratlon. Oxbow I.1kes.
<br />mMshl.s /1ehind naturJ.l lever-s <Fig 55). .Ind
<br />underllow that m,lInt3ineJ pt'rm,inem pools uUflng
<br />urou~ht were fed by these water tables. Perh,lps
<br />n1llre ImpOrt;\nrl~'. hedrock LluslnF (ormation of
<br />
<br />-
<br />
<br />I
<br />
<br />-_"~ 1
<br />--....-
<br />-
<br />
<br />-
<br />-
<br />'''r
<br />
<br />~
<br />
<br />~
<br />'7"
<br />
<br />
<br />"l
<br />
<br />Figure 55. TOPOCk MarSh along the lower Colorado River.
<br />Arizona, is anlfically maintained. bul must resemble
<br />condlllons lhat eXisted m oxbow la~es, marshes behind
<br />nalural levees. and backwaters prior 10 human moclillcatlons
<br />of the system, Photograph prOVided by the U S Bureau of
<br />Reclamation.
<br />
<br />27
<br />
<br />01106
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