Physiological Consequences of Overwintering in ...

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Physiological consequences of overwintering in streams: the cost of acc%imitination? Caw. ). Fish. Aquat. Sci. 45: 443-452. Proximate body composition and ...
uences of Ove intering in Streams: The Cost imitization? Richard A. Cunjakl Can. J. Fish. Aquat. Sci. Downloaded from www.nrcresearchpress.com by Depository Services Program on 08/11/14 For personal use only.

Department sf Biolsg~University sf Waterloo, Waterloo, 0~8. M2L 3 6 1

Cunjak, 8 . A. 1988. Physiological consequences of overwintering in streams: the cost of acc%imitination? Caw. ). Fish. Aquat. Sci. 45: 443-452. Proximate body composition and hematological parameters of wild brook (Sa8veliwus dowtinalis) and brown trout (Salrno erutta) from five sites were monitored over three winters. For both species, and for immature and mature fish, lipid levels were Iswest (and water content highest) in winter. Lipid levels were most rapidly depleted (to between 2 and 4% wet weight) in early winter (November-December)* Brown trout and immature brook trout appeared to suffer a second period of depletion in late winter (February-March$ in contrast with spent brook trout. Protein and ash components were relatively stable between dates. Serum protein levels varied gready but generally indicated a decline in early winter from high summer (August) values prior to increasing in May. Such &ends were most obvious during the winter of 4 9 8 M 4 , the harshest of the three winters of study. In the winter, serum glucose concentrations peaked in November. These phys"eQIgica8 relationships corroborate earlier findings that early winter is a stressful period of acchmatization to rapidly changing environmental conditions. Even the relatively stable discharge and temperature regimens of spring-fed tributaries are insufficient to offset the effects of early winter. h'auteur a contrdl$ la composition eorwm9le approximative et certain5 pararnstres h6rnatologiques d'ornbles de fontaine (Salvelinus fontisealis)et de truites brunes (SaBms trutb) sauvages de cinq sites au cours de trois hivers. Chez les deux esphces, et tant chez les poissons irnrnatures que matures, les teneurs en lipides etaie~ntles moins 4lev$es get Bes teneun en eau les plus6lev6es) au tours de I'hiver. La teneur en Iipides declinait le plus rapidernent (jusquf3 2 A 4 % dae poids hurnide) au debut de I'hiver (novernbr&6cembreBB Les gambles de fontaine irnrnatures et les truites bruwes semblaient subir uwe deuxi&me p k r i d e de disparition des lipides vers la fin de I'hiver (fevriermars), ce qui nf&taitpas le cas des ombles de fontaine ayant d4jA fray4. Bes teneurs en progines et en cornpssantes des cendres sont demeurks relatiwment cowstantes entre ces dates. Les teneurs en prot6ines s$riques variaient de faqon importante mais prthentaient, par rapport aux valeurs 4lev6es d'6t4 (soot), un d4clin au debut de I'hiver avant de s'accrottre A nouveau en mai. Ces tendances snt 6t4 les plus apparewtes au cours de I'hiver de 19831984, le plus dur des trois hivers de lf&ude. En hiver' les concentraitcsns de gDueose serique presentaiewt un pic en novernbre. Ces relations physiologiques appuient des &sultaas anterieurs indiquant que le d$but de I'hiver constituait une p$riode de stress correspondant A B'acclirnitation 3 des conditions envirawnernentales rapidement changeantes. M$me les dkbits et les r6gimes de tempratures ~[ativernentstables associes auw tributaires aliment& par des sources ne suffisent pas 3 compenser les effets du debut de I%iver. Received ApriB 29, 1987 Accepted November 2, 8 987 QJ925l)

D

eelining condition md depktion of energy reserves generally typify the physiologied changes gg~qcewgin fishes during winter. In a subarctic river in Quebec, Cunjak md Power (1986~1) found that semm protein levels and body lipid content in brook trout (e9lwel~s$onti~oc~Iis) ddined over winter. DutiH (1986) estimated that i arctic char (23. alpinus) from Nauyuk M e , N.W.T., roximakly 30% of their energy reserves during winter when hey were ntly fasting. The lipid content in various tissues of ciwo (Coregonus smibula) was at a minimum in December relative to other seasons (Eizedo et d*1975), and Bulow et d. (1981) reported depressed tissue W A conan&atioms (mindicator of protein synthesis) in l&e-dwelling bluegills (Lepsmis macrochs'rus) during winter. nt sf Fisheries md Oceans, Science Branch, Gulf Region, P.0. Box 5030,Moncton, N.B . E1C 9BQ. Can. J. Fish. shqmt. Sci., V08. 45, 1988

A species9rearing envkonment can greatly influence its biological characteristics over a broad gmgraphicd rmge (kggett md Carscadden 1978;~ 8 1 xet1d a1984) or within a single fiver system (Carl a d Healey % 984; Heggkrget et al 1986). Riddell aid Leggett (1981) suggested an adaptive basis to explain the variable life history patterns and m o ~ h o l ~ g i ctraits d in juvenile Atlantic salmon (Salmo salar) from two streams with different o v e m i n t e ~ ghabitats. Similar variability for physiological pameters may also be measurable where ~ocalizedstream conditiom (e .g . goundwater dischge zones, proximiv to tributaries, lakes) occur within a river system. In the present study, the primary objective was to &scribe changes in the levels of energy stores in s@em-dwelIhgbrook trout md brown trout (Saimo t r u t t ~during ) winter. This was attempted by monitoring hem&ologicd parameters (indicative of a short-term response) md proximate body composition, which tends to change at a relatively slower rate, especially at low water temperatures (Elliott 1976). BE.

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To assess h e possible influence of locdized stream conditions, I analyzed the data separately for those sites where gomdwater discharge con~butedsipificantly to stream flow ( s p ~ g - f tributaries) d c o m p a d with %%me 'h a i n river9' sites where groundwater con~butionswere minimal. I hpothesized that the relatively stable temperature md discharge conditions in the tributaries were less energetically & be the situation in the main river (see Edwmds et d . 1979). Cunj& md Power (1986b) showd that l w d hy&slogical conditions, spcifiedly groundwater inputs, can greatly influence bout khaviour in winter.

Study Area m e @redktRiver, a fifth-order stream in southern 0ntaio, drains an area sf 850 b2 a d dischages into Lake O n t ~ at o 43"33'N, 79"33'W. Five sites (Fig. 1) were chosen because they provided variable species assemblages and habitat c istics (Table I). Site descriptions for C d d o n , Spring Tributary, and North Brmch were previously given by @unj& and Power (1986b), and so, only desciptions f a West Branch and Black Creek sites follow. West Branch (Fig. 1, No. 4) specimens were collected in the lower 300 rn of this stream. The same fish species were present as in the North Branch and no barrims to access exist between these bmches. This stream section has the highest gradient

mwg the five study sites a d boulder is the main substrate type. Relative to the North Branch, the West Branch has slightly r water temprames; it dso freezes earlier and thaws later. Ice accumulations were the highest observed, often covering entire stream sections. Black Creek (Fig* 1, No. 5) enters the middle reaches sf the Credit River. Bmok bout are the most co but a few juvenile norhem pike (Esox lucius) md white sucker (Catostomus c~rnrnerson~ are dso present. It should be noted hat s s m flow regulation occurs at the Actsn reservoir 5 h upseem. Subbate is dy sand m d gavel with scdkred mats sf watercress (Nasfurtium oflieinale) which persist ksughout the yea, as at the Spring Tributary site. Ice cover is minimal. During the winters of 1983-84 and 1984-85, water temperatures were monitored on Pamy-Ryan themogaphs at the g md North Brmch sites. Water Black Creek, S p ~ Tributary, temperatures were Ass taken d u ~ all g field trips. Dissolved oxygen was dways at or near saturation at d l study sites.

Brmk and bmwn trout were periodicdly sampled during three winters by electrofishing fiom the five study sites. SFeific sampEpag dates can be derived from the pints on h e figures for the various physiologicd pameters (see below).

BARRIERS T O UPSTREAM MBQRATBBN

K i LOMETRES

BRAUPTOM

FIG. 1. The Credit River showing locations of h e five study sites: (I) Cdedon, (2) Spring Tributary, (3) North Branch, (4) West Brmcb, (5) Black Creek. Can. J. Fish. &UQL

Sci. Val. QS5 1988

TABLE1. Physical and ehemid cbmckGstics o f the five 8eLmd$r sites on the Credit fiver. The m g e s of chemicd pameters were based on month1y meawments throughout 1984; physicd measurements are b a d on data recorded between 1982 md 1985.

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Mean discharge Smm (rn3.s - I) gradient ( m . h - B ) Summer Winter

Wdater temperature ('C)

Mean Snmer W h k r surface ice i m m minimum cover (%)a

Water chemistry (mud range) pH

Turbidity Ccegnducajiviegr Water h a h a s (N.T-U.)( p S i . ~ m - ~(mg ) CaCOs*L-')

during winter field trips. uPem~tage of wetted stream surface eoverd by ice as mesis %o measurements taken. Ccpnsi&~dto be same as for Cdedon site only 3.5 h upstream.

Spring (May) and su er (August4eptemkr) collections were dso made for compkson. !dl smplhg was p d o m e d ktween 1100 and 1700 md within the s m e s ~ secfions m at each site. Extensive ice a c c ~ u l a ~ o (anchor ns md surface) precluded sampling in mid-Dmmkr 1983, except for the spring-fed tributary sites (Black Creek and Spring Tributary). Collections from the West Branch were not started until Much led within approx1983. For a given perid, d l sites high water condiimately 1 wk with the followhg tions in M m h 1985 following mllections at the Cdedon, Spring Tributary, a d Black Creek sites resulted in the North king taken 2 wk later; no West Branch sample because of the difficult conditions. trout having completed at l e s t 1 yr of postemergent growth in the slream were sampled. For each fish, I

esized that the energetic investment of repduction might differentially affect mame fish relative to a d &at such a difference might be lowing winter months. Matme fish showed pmmunced gonadal development (August-Sepkmk r ) , were ripe (Octokr-Novemkr), or were spent (Novemkr-May). S&XlXl 0.85) between sexes, on a given sampling date, for any of the rneasured physiological or biometric v&ables, The only exceptions were for female b m k &out which had sig~ficmtlyhigher (P < 0.85) semm glucose md protein levels than males once in 13sampling dates md f a femde brown trout which had a higher lipid content than males (P < 0.05) once in eight sampling dates. The rarity sf such differences was the basis for combining sexes fm subsequent mdyses. Also, there was no instance 445

TABLE2. Biornetric data for I WT = wet weight (g); 8s =

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Spring Tributary

Black Creek

Cdedow

North Branch

West B m c h

Brown trout

Mean w 2 BrmgeB

SE

Bll

TABLE3. Proximate body cornpsition sf trout from the Credit River sites as measwed on t h e dates. Vdues of each rsmpnent are mean percentages of whok wet weight + SE. n = sample size; B = Black Creek, C = Cdedon; N = North Branch; S = Spring Tributary. Date

Site n

Water

Lipids

&okh

Ash

Sum % components

Brook trout

Brown &roast

of statistical significance between sexes for my variable whew poling all sampling dates. To justify the pooling of data into ""QH-ib~rny~~ or 66maiw river9' categories, each variable (five physdologicd, two biometric) was tested for intraeategory differences. For the tribu446

ta-y data, I found no significant differences (P> 0.85) for any of the physiolgbgical variables. There were however, significant differences (P < 0BO1) for fork length and wet weight; Black Creek brook trout were consistently lager than Spring Tribaataq trout (Table 2). Among main rher sites, there were no Cm. J. Fish. A q w t . Sci. Vsl. 45, 1988

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significant differences (P > 0.05) for my of the physiologicd variables or biometric variables. This was true for brook trout as well as brown trout. Therefme, at l a s t for the physiological variables, the poling of data a p p m justified. Note that M y lipid assays were not gsedomd on brook trout from the West Branch; intersite c o m p ~ s o n sfor this component were only made between the North Brmch and Cdedon sites. Few mature brown tmut were sampled because this species matures at a lager size than brmk trout (Table 2) a d because trout large enough for recruitment by the recreational fishery (>38 cm) were not retained. Consequently, all brown trout were combined for the analyses. On those few dates where a representative sample of i ure and mature brown trout were capn a s (P > 0.05)were found for my tured, no significam of the physiol%icd variables. Mem protein and ash values were similar between sites and dates (Table 3). At the tributary sites (where analyses were performed on three dates), body lipids and water were each significantly different (P< 0.625) ktween dates whereas protein and a h were not (P > 0.85). Determination of d l four body compnents for a s m p k of fish dso provides a measure of tbe accuracy of the analyses. A sum sf lOQ 2 5% is generally acceptable (Banes 1981) md this was achieved!in each instance (Table 3). Lipid content was generally inversely prqmtiond to water content (Fig. 2). For both species and for immature as well as mature fish, lipid levels were lowest (and water content highest) in winter with rapid accumulation in spring (May). 'his trend was generdly consistent at tributary and main river sites except that the spring increase in lipids, in 1983, was much the latter (Fig. 2A, 2B). Relatively high lipid levels i (August) were similar at both site categories prio een 2 and 4%) in early winter (Novemberre and mature brook tmut displayed s i m i h r change though botb winters with one possible exception. After the initial period of depletion in early winter, lipid levels of mature trout remained stable or increased during the remainder of r (December-March) before abre brook trout, however, accelerated accretion in of depletion in late winter seemed to show a seco (February-Mmch) as evidenced by declining lipid content md a concomitant in water content. This trend, admittedly based on small sample sizes, was only apparent during the winter of 198344 md particularly at the tributary sites. Lipid-moisture relationships in brown trout (Fig. 2C) most closely resemble hose of immature brook bout, at least daring 1983-84, with a Ioss of lipid in early winter (and water increase) followed by a second period of depletion in late winter. This similarity might be expected, since 83.5% of the brown trout sampled in winter were i re. Mean lipid content was similar between species except that brmk trout displayed the lowest percentages (