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<br />Marsht's .1Od rlP:H1.\n plants wt"rt" ldl l11gh and dry. <br />and disappeared The etnsl\'e pu.....cr .....as <br />(;oncentrared downward hy 111lo"h channd wa]1s. <br />Fishes adapted [t) crus in h.1hltau. [hose whl(h <br />could h\,t In rhe hard'fllck c.ln~'on reacht"s of <br />streams. .....ere \(;\fu:lr atfeued by rhls chan!,!:. F]ow <br />almost cerraln]~' bC(Jmt' It"ss rt"lJahle as upstreJm <br />~roundwau:r rt."st."rvoirs Wt'rt d[;lined. bUI Ihl: hahlta[ <br />mherwise rt:maloeJ similar 10 before, On tht" ()[her <br />hand. /ishes dependEnt; on constant. cool Inflow 01 <br />~round""ar{'r. J.melLorJ.tllJn of !louds. nr lht' ('rcscn(t. <br />of quict hJ.~'IL[ars .1]on,~ meandcflng channels. wt:re <br />suddenly J.nd snl"fcly Impaued <br /> <br />Ecology of Prcscm Systems <br /> <br />PhYSIC.ll nlOJlflons In lmcrmeJlate'elt;~\-;ltL()n <br />streams J.Tt' hl~hly \'arl;lnle. Summer WJ.ter <br />tempt"t.lturt'S appro;lch ~() C In .It'rernoon (Fig, 24). <br />,!Od dr\)r to ILl 0 C ur lower at dayort'.lk_ <br />Rdativt:ly cool water. dl:splte air t{'mperatur!:s \If <br />.1_,,_,0 C or more. l~ Jue to rbe high n'apor.ltHln <br />rares In dry Jt:serr alT Only on rare ~unn~' d.I~'S With <br />hi~b humidity Jo stteam remrtrarurt:s flSt' aoon' <br />'2_2 C; rherm.1I dc,Hh uf fishes ha~ been rewrded <br />under such (pndmons Sh,IJlnt: hh .1 profound <br />etft,ct. .lOd a crt"t:k wnh a]tern.lIlnt:- tlow througb <br />wide, unsll.ldl:d ch:lOnds tht"o n.1rrow-. dark Glnynn... <br />mar \'J.ry ;llon~ its course J.! tht' s,lme rime of thy <br />In winrn. strt".lm mJ.tf:lOs oltt"n fl\{' tll 25 ( on <br />,"nny d"., Ch'nnd "mp'''''"''' ,i" no 12.] C. <br />llT perh;ips murt", .IOJ rJ.tel~' dmp 10 kss than 5 C <br />.It Ol).:ht lee nonethelt"ss forms un ISO];HtJ <br />backwaters llO espt"uJ.lJy wId nl~hts. <br /> <br />35 <br /> <br /> 95 <br />"'-'11161977 90 <br /> 80 <br /> 70 <br /> ~ <br /> 60 0 <br /> 50 <br /> 40 <br /> 32 <br />6 <br /> <br />30 <br /> <br />25 <br /> <br />20 <br /> <br />I' <br /> <br />15 <br /> <br />10 <br /> <br />..Ian '5.HP? <br /> <br />5 <br /> <br />o <br /> <br />6 <br /> <br />Noon <br /> <br />Figure 24 Summer and winter water Temperatures over 24- <br />hour periOdS In Bomta Creek Arizona <br /> <br /> <br />Figure 25 Above' Boulder substrate in a high-gradient <br />!TIbutary to the RIO de Bavlspe. Sonora. Photograph by D. <br />A Hendrickson Below' Sand/gravel substrales 10 a wide <br />segment of Aravalpa Creek, Anzona <br /> <br /> <br />These sUt..J.ms carry rcmukable IO;lds of material <br />erodl.'d Irom the mouor.llns through which they pass. <br />SubsuJ.rl's J.re tYPIcally of boulder J.nd cobble at <br />hl~ber e1t"V.1tlOns, ~rJ.dlng [0 ~ra\'{"]s and sand lower <br />dtlWn (FiF_ 2')). Turbidlrles are high during tloods. <br />but r;HtLcles tend to be 1J.T!,e in size and most <br />strc.lm" dear qUlck]y. Because manr watersheds He <br />TIlcky, burt"n ot' \'t"~etJ.tlUn. J.nd Impervious. <br />..heettlow qUh,:k]y (oncentrJ.tes IntO ch.lnnels to <br />produce .inru!'t and \"lo]ent discharges. L'nlike <br />Hre.lms 10 more temperate zones. most of the annual <br />W.Ht.r ~'leld of these streams is dUTlng dash /loods <br />(FI,C. 26). r.Hher thJ.n .lS slow, constant discharge <br />thrl)u~h(lul [he ye3T. <br />Chemically. most of these streams remalO well <br />within tht. limits for healthy fish populations. Ther <br />h.I\'e mllrt" tot.!] dissolved solids than mountain <br /> <br />13 <br /> <br />G1G8!] <br />