Diel and seasonal patterns of habitat use by fish in a natural

Bull. Fr. Pêche Piscic. (1997) 346 : 573-588 — 573 —

DIEL A N D S E A S O N A L PATTERNS O F HABITAT U S E BY F ISH IN A N A T U R A L S A L M O N ID B R O O K : A N A P P R O A C H T O

T H E F U N C T I O N A L R O L E O F T H E R I F F L E - P O O L S E Q U E N C E .

J . M . R O U S S E L , A . B A R D O N N E T

INRA, Laboratoire d 'Ecologie Aquat ique, 65 rue de Saint-Br ieuc, 35042 Rennes Cedex, France.

A B S T R A C T

The spat io - tempora l use of the riff le-pool sequence in a natural salmonid brook w a s

studied by day and night for one year on b rown trout (Salmo trutta L.), bul lhead (Cottus

gobio L.), European minnow (Phoxinus phoxinus L.) and s tone loach {Barbatula barbatula L.).

Young-of- the-year b rown trouts were more numerous in riffles in spr ing, whereas o lder trouts

chose pools. A diel pat tern of habitat use between riffle and pool was observed for one-year-old

individuals, w h o moved towards riffle dur ing dayl ight in summer and early fall. Seasonal

var iat ions in t rout densi t ies were related to movements at a large spatial scale before and after

the spawn ing per iod . Bul lhead preferred riff les to poo ls , especial ly young-o f - the-year

individuals, even if th is preference decreased dur ing ontogenesis. On the contrary, minnow

chose pools th roughout the year and seemed to leave the ri f f le-pool sequence for spawning,

whereas no preference was observed for loach except for riffle dur ing the spawning period.

Results and an approach to the funct ional role of the r i f f le-pool sequence in lowland salmonid

brooks are d iscussed.

K e y - w o r d s : b rown trout, bul lhead, European minnow, s tone loach, sa lmonid brook,

r i f f le-pool sequence, spatial heterogeneity, diel preferences, seasonal preferences, funct ional

habitat.

V A R I A T I O N S J O U R N A L I È R E S E T S A I S O N N I È R E S D ' U T I L I S A T I O N D E L ' H A B I T A T

P A R L E S P O I S S O N S E N R U I S S E A U À S A L M O N I D É S : U N E A P P R O C H E D U RÔLE

F O N C T I O N N E L D E L A S É Q U E N C E R A D I E R - P R O F O N D .

La success ion rad ie r -p ro fond cons t i t ue le pr inc ipa l é lément d 'hé térogéné i té

géomorpho log ique en pet i ts cours d 'eau à truites peu pentus. Ces deux faciès présentent des

caractér ist iques d 'écou lement radicalement dif férentes qui supposent des condi t ions d'habitat

elles aussi t rès dif férentes. Dans ce travail, l 'uti l isation spat io- temporel le de la séquence

radier-profond a été étudiée de jour et de nuit tout au long d e l 'année pour les espèces les plus

souvent rencontrées dans ce type de ruisseau, à savoir : la t rui te (Salmo trutta L.), le chabot

(Cottus gobio L.), la loche (Barbatula barbatula L.) et le vairon (Phoxinus phoxinus L) . Les

juvéniles de trui te de l 'année occupaient préférent iel lement les radiers (au moins au printemps)

alors que les truitel les d 'au moins 1 an ont mont ré un net choix pour le profond. Les

compar t iments radier et pro fond ont été uti l isés d i f féremment au cours du nycthémère par les

truitelles d 'un an, don t une partie se déplaçai t vers les radiers le jour en pér iode estivale. Les

f luctuat ions saisonnières de densi tés ont été expl iquées par des di f férences de recrutement

Reçu /e 23 mai 1997

Accepté le 17 juillet 1997

Received 23 May, 1997

Accepted 17 July, 1997

R É S U M É

Article available at http://www.kmae-journal.org or http://dx.doi.org/10.1051/kmae:1997005

http://www.kmae-journal.org

http://dx.doi.org/10.1051/kmae:1997005

Bull. Fr. Pêche Piscic. (1997) m : 573-588 — 5 7 4 —

annuel et des mouvements de popula t ion avant et après la reproduct ion. Le chabot préférait le

radier au profond, cet te préférence était très marquée pour les plus jeunes individus puis

s 'a t ténua i t au cours de l 'ontogenèse. Au contraire, le vairon a nettement préféré le profond et

aucun changement n'a pu être mis en évidence ; cependant, les faibles densités en juin étaient

p robab lemen t liées à des dép lacements hors secteurs pendant la reproduct ion. La loche quant

à el le était répartie à part égale entre les deux types de faciès, sauf en juin où sa préférence

pour le fac iès radier était p robab lement liée à la recherche d 'un habitat de reproduct ion.

L'analyse éco-é tho log ique des résultats obtenus dans ce type de mil ieu permet d 'approcher le

rôle fonc t ionne l de la séquence radier-profond à trois des échelles bio logiques de la structure

des ich tyocénoses : peuplement , popula t ion et individu.

Mots -c lés : trui te fario, chabot , vairon, loche, ruisseau, séquence radier-profond,

hétérogéné i té spatiale, préférences journalières, préférences saisonnières, habitat fonct ionnel.

I N T R O D U C T I O N

Natural salmonid streams provide a large set of physical habitat condi t ions for the

deve lopmen t of aquatic fauna, and f ish usually inhabit most available habitats. The stream fish

c o m m u n i t y is generally c o m p o s e d of benthic and nectonic species exhibi t ing different habitat

pre ferences and segregated accord ing to water dep th , velocity and subst ra tum size gradients

(GRIFFITH, 1972 ; JONES, 1975 ; BAGLINIÈRE and ARRIBE-MOUTOUNET, 1985 ; GLOVA and

SAGAR, 1 9 9 3 ; GIBSON ef a / , 1993). Spatial heterogeneity and physical f ramework are

therefore important fac tors in descr ib ing stream fish habitat. In their review, NIEMI era / . (1990)

c o n c l u d e d that the loss of habitat diversi ty due to physical alterations of the stream channel was

the mos t c o m m o n impact assoc ia ted wi th long recovery t imes for fish populat ions. From

FRISSELL ef al. (1986), physical habitat in streams can be def ined as hierarchically nested

subd iv is ions , f rom the largest scale of the entire river basin and drainage network, to the

smal lest microhabi tat scale wh ich refers to point condi t ions in the channel . At a median and

loca l sca le , an impor tan t source of physical habi tat heterogenei ty d e p e n d s on

geomorpho log ica l processes in the st ream channel . The channel type, w id th and slope,

c o m b i n e d w i th f low obst ruc t ions in the stream bed (blocks or coarse woody debris), generate

part icular hydraul ic cond i t ions that favour scour and deposit ional processes. These general

mechan i sms contr ibute to the fo rmat ion of channel geomorphic units, also cal led habitat types,

de f ined as areas of relatively homogeneous depth, velocity and subst ra tum character ist ics.

App l i ca t i ons in fishery management have led to the proposal of several c lassi f icat ions of habitat

t ypes (BISSON ef a/., 1982 ; FRISSELL ef a / , 1986 ; MALAVOI, 1989 ; BRYANT ef a / , 1992 ;

HAWKINS ef al., 1993 ; JOWETT, 1993 ; RABENI and JACOBSON, 1993). In spite of variability

be tween observers w h e n naming habitat units (ROPER and SCARNECCHIA, 1995), two basic

uni ts co r respond to the c o m m o n l y used terms « riffle » and « pool », a general level of resolution

tha t segregates shallow fast - f lowing and deep s low-f lowing habitats. In most alluvial valleys, the

r i f f le-pool sequence is a natural habi tat feature o f the river channel that occurs regularly (see

B ISSON and MONTGOMERY, 1996 for synthesis). Therefore, the riff le-pool sequence as an

ent ire habi ta t unit could be of great interest for f ishery biologists.

In a one-year study, we evaluated diel and seasonal variations in riffle and pool util ization

by f ish in a typical ly alluvial sa lmonid brook in Brittany, France. Two quest ions were examined

in detai l : 1 - H o w is the f ish commun i t y (species and life stages) d iv ided between riffle and pool

habi ta ts ? 2 - Are there tempora l changes (diel or seasonal) in their habitat type preference (riffle

or pool) ? The role of the riff le-pool sequence as a funct ional habitat feature for fish in salmonid

s t reams and management impl icat ions are then d iscussed.

S T U D Y S I T E

The s tudy was conduc ted in 1995-96 in the Kerlégan brook, a tr ibutary of the Scorff river,

Bri t tany, France (Figure 1 ). Its total length is 7.2 k m and it drains an area of 20.4 k m 2 . The mean

gradient is 13 m.knv 1 and the bo t tom substratum is mainly gravel-sand, which corresponds to


the « pool-r i f f le reach » accord ing to BISSON and MONTGOMERY 'S s t ream classi f icat ion

(1996). Bri t tany has a temperate oceanic c l imate, and mean daily water temperatures recorded

in the brook varied f rom 17°C (Aug-95) t o 5.5°C (Dec-95). M in imum (Jun-95) and m a x i m u m

(Sep-95) month ly precipi tat ions were 10 m m a n d . 180 m m , respectively. As in most sa lmonid

rivers in Brit tany, the deve lopment of macrophytes (especially Ranunculus spp) a lso contr ibutes

to seasonal modi f icat ions on channehhydraul ics (HAURY and BAGLINIÈRE, 1996). Carex (Carex

paniculate) f o rms the most f requent banks ide emergent vegetat ion and is essential ly d is t r ibuted

along pool margins of the brook.

F i g u r e 1

M a p o f t h e s t u d y s i t e .

F i g u r e 1

C a r t e d u s i t e d 'é tude.

M A T E R I A L S A N D M E T H O D S

Four surveys were conduc ted in June 1995, Oc tober 1995, January 1996 and Apr i l 1996.

In the ki lometre before the conf luence wi th the Scorff river, three similar r i f f le-pool sequences

spaced 50 to 150 metres apart (see Table I for habi tat descr ipt ion) were electrof ished with an

AC generator (200 W, cont inuous output) us ing the removal method (DE LURY, 1951). In order

to compare day and night densit ies in the same sequence, in each season, t w o sequences

were electrof ished by day (at least 3 h after dawn) and one by night (at .least 3 h af ter dusk).

Two weeks later, an inversed sampl ing (one unit by day, t w o units by night) was per formed. At

night, the sampl ing area was lit wi th a 500. W halogen spot light. There w a s no electrof ishing

dur ing full m o o n nights. A special d ipnet design (mesh 3 mm) pre-pos i t ioned across the channel

10 k m

O c e a n


and above the water surface made it possible t o parti t ion each sequence in c losed riffle and

poo l hab i ta ts synchronously wi thout wad ing just before electrof ishing. When riffles and pools

were c l o s e d , an operator carry ing a 30 c m ring anode waded f rom the downst ream to the

ups t ream end of each sequence. Two other peop le netted fish with 20 c m ring net handles

(mesh 3 mm) and special 60 c m semi-c i rcular sect ion net handles (mesh 3 mm) held flat against

the b o t t o m in the riffle. All f ish caught were anesthetized (phenoxyethanol), measured (nearest

mm) and then released inside the habi tat t ype where they were caught. Each t rout w a s

indiv idual ly marked wi th a miniature Passive Integrated Transponder (PIT), and scales were

s a m p l e d to determine age in the laboratory.

A g e st ructure in non-sa lmon id populat ions was evaluated by graphic analyses of modes

in b o d y length f requencies (BHATTACHARYA, 1967). Mean populat ion densit ies in pool and riffle

were es t ima ted for day and night samples by the CARLE and STRUB method (1978) using

Micro f ish 3.0 sof tware (VAN DEVENTER and PLATTS, 1989). Hypotheses about dif ferences in

day and night use of riffle and poo l were tested wi th non parametr ic Wi lcoxon-Mann-Whi tney

tes ts ( W M W test).

T a b l e I

M e a n r i f f l e a n d p o o l c h a r a c t e r i s t i c s a n d s e a s o n a l h a b i t a t v a r i a t i o n s i n t h e t h r e e r i f f l e - p o o l

s e q u e n c e s s t u d i e d .

T a b l e a u I Carac tér is t iques méso log iques m o y e n n e s e t v a r i a t i o n s saisonnières s u r l e s t r o i s s é q u e n c e s

r a d i e r - p r o f o n d d e l 'étude.

R I F F L E P O O L

Total length (m) 24 26

Jun. 95 2.9 2.8

M e a n width (m) Oct. 95 2.4 2.1

Jan. 96 3.1 2.9

Apr. 96 3J 2.9

M e a n surface area (m 2 ) 69 73

Jun. 95 8.6 27.2

M e a n depth (cm) Oct. 95 7.1 24.2

Jan. 96 22.5 41.7

Apr. 96 15 33

Jun. 95 23 8

M e a n velocity Oct. 95 14 5

(cm.s" 1) Jan. 96 51 27

Apr. 96 20 8

Jun. 95 gravel silt - sand

Bottom substrate Oct. 95 and silt - sand

(Wentworth scale) Jan. 96 small sand-gravel

Apr. 96 cobbles sand-gravel

Jun. 95 83 25

Macrophyte Oct. 95 42 8

cover (%) Jan. 96 33 25

Apr. 96 75 25

Jun. 95 58

Stream flow ( I . s 1 ) Oct. 95 28

Jan. 96 335

Apr. 96 85

Bull. Fr. Pêche Piscic. (1997) 346 : 573-588 — 5 7 7 —

R E S U L T S

A total of 11 species were caught on each sampl ing date. Roach (Rutilus rutilus L.), dace

(Leuciscus leuciscus L.), gudgeon (Gobio gobio L ) , At lant ic sa lmon (Salmo salar L.) and eel

(Anguilla anguilla L.) were minori ty species., Numerous juveniles of sea (Petromizon marinus L.)

and brook (Lampetra planer! Bloch) ' lamprey had bur ied themselves into the silty habitats of

pools , and so inadapted electrof ishing prec luded correct est imat ions of their populat ion

densit ies. Bul lhead (Cottus gobio L.), European m innow (Phoxinus phoxinus L.), s t one loach

(Barbatula barbatula L.) and b rown trout (Salmo trutta L.) represented over 90 % of all individuals

caught dur ing the four surveys. These were then more precisely invest igated. For each survey,

no signif icant dif ference was found between the total number of fish caught dur ing the first and

the second electrof ishings wh ich took place t w o weeks later (p>0.10, W M W test). This indicates

that there was no inf luence of successive electrof ishings on species popula t ion densit ies.

B u l l h e a d

Bullhead was the most numerous species in the brook, and represented 57 % of all

individuals caught during the entire exper iment . No diel dif ference was observed in its

d istr ibut ion wi th in the riff le-pool sequences (Figure 2). Densit ies in the poo l were constant and

signif icantly lower (1 ind/m 2) than in riffle (p<0.05, W M W test). On the contrary, densi t ies in riffle

var ied f rom 6 i nd /m 2 (Oct-95) to 1 . 5 i n d / m 2 (Jan-96) over the year. These dif ferences were related

to demograph ic changes within the popula t ion. Three life stages were clearly identi f ied by body

length f requency analysis (Figure 4) : young-of - the-year (0+), one-year-o ld (1+) and^older fish (*1).

0 + appeared in electrof ishing samples in Jun-95 , but densit ies were probably underest imated

because of their small body size (20 m m on average). After a first summer, their mean body size

was 38 m m (Oct-95) making them easier t o ca tch. This explains why the highest densit ies of

bul lhead were est imated in riffles in Oc t -95 (6 ind/m 2 ) , 58 % of wh ich were 0 + . More than 90 %

of all 0* electrof ished came f rom riffles. During winter, densit ies strongly decreased for all life

s tages (1.5 i n d / m 2 in Jan-96). The 0 + still represented 55 % of the total populat ion, but their

cho ice for riffle habitat was less marked (78 % ) . In spring (Apr-96), 32 % of the new one-year-old

cohor t was caught in pools, wh ich cor responded to the proport ion of the tota l populat ion that

was electrof ished in pools. Growth a lmost s topped dur ing winter, as shown by the mean body

size in Apr-96 (39 mm). For older bul lheads, mean body sizes showed little increase f rom

summer to winter (from 47.5 to 49.8 m m and f rom 64.5 to 65.6 m m for 1 + and ' 1 , respectively),

suggest ing a higher growth rate in spr ing for this species.

M i n n o w

No diel dif ference was found in the distr ibut ion of minnow wi th in the riff le-pool

sequences (Figure 2). Unlike bul lhead, m innow densit ies were a lways lower in riffles (from

0 i nd /m 2 in Jun-95 to 0.4 in Apr-96) than in pools , and this was signif icant in Oct -95 , Jan-96 and

Apr-96 (p<0.05, W M W test). However, densit ies in pools varied f rom less than 0.1 i nd /m 2 (Jun-95)

to 2 i nd /m 2 (Oct-95) over the seasons. Like for bul lhead, these di f ferences were related to

demograph ic changes with in the populat ion. Only the young-of - the-year cohor t (0+) w a s clearly

identi f ied f rom analysis on body length f requencies. 0 + appeared in the Oct -95 sampl ing and

represented only 32 % of the minnow populat ion (Figure 4). Their mean body size w a s 30 m m

and it was not clear whether the electrof ishing had been efficient or not. No 0 + was caught in

Jan-96, and their growth almost s topped in winter as shown by their mean body size in Apr-96

(33 mm) when 29 % of m innow caught were 0 + . No 0* and only a few older individuals were

electrof ished in Jun-95 (Figure 2).

S t o n e l o a c h

Stone loach densit ies were global ly lower than those of bul lhead and minnow (Figure 2).

No signif icant habitat cho ice was recorded, except in Jun-95 when densi t ies were highest in

riffle (0.5 ind /m 2 ) and lowest in pool (0.1 ind /m 2 ) . No diel dif ference was found in the distr ibut ion

Bull. Fr. Pêche Piscic. (1997) 346 : 573- — 5 7 8

M i n n o w

S t o n e l o a c h

B u l l h e a d

i

1 I 1 1 1

J u n .

. O c t .

. J a n .

* Apr .

J u n .

= J

i i

i I i

i = J

i i

i I i

i = J

i i

i I i

i

1** O c t .

* J a n .

' * * Apr .

+ +

Jun .

Oct .

J a n .

Apr.

0 ,8 0,6 0 ,4 0,2

D e n s i t i e s i n p o o l ( i n d / m 2 )

0,2 0,4 0,6 0,8

D e n s i t i e s i n r i f f l e ( i n d / m 2 )

f

[ 1

^ : :

— ' 1

F i g u r e 2

D i e l a n d s e a s o n a l d e n s i t i e s e s t i m a t e d i n r i f f le a n d p o o l f o r b u l l h e a d , m i n n o w a n d s t o n e l o a c h .

B l a n k a n d h a t c h e d b a r s r e p r e s e n t d a y l i g h t a n d n i g h t s a m p l i n g s , r e s p e c t i v e l y . H o r i z o n t a l l i n e s

r e p r e s e n t a 9 5 % c o n f i d e n c e l e v e l f o r e s t i m a t e d p o p u l a t i o n s ( p < 0 . 0 5 , S t u d e n t t d i s t r i b u t i o n ) .

S t a t i s t i c a l d i f f e r e n c e s i n d e n s i t i e s b e t w e e n r i f f le a n d p o o l , b y d a y a n d n i g h t , a r e e s t i m a t e d b y n o n

p a r a m e t r i c W i l c o x o n - M a n n - W h i t n e y t e s t s (* : p < 0 . 0 5 ; ** : p < 0 . 0 1 ) .

F i g u r e 2

E s t i m a t i o n s journal ières e t saisonnières d e s densités e n r a d i e r e t e n p r o f o n d p o u r l e s c h a b o t s ,

v a i r o n s e t l o c h e s . L e s b a r r e s b l a n c h e s e t hachurées représentent l e s échant i l lonnages d e j o u r

e t d e n u i t , r e s p e c t i v e m e n t . L e s t r a i t s h o r i z o n t a u x représentent l e s i n t e r v a l l e s d e c o n f i a n c e à

9 5 % ( p < 0 , 0 5 , d i s t r i b u t i o n t d e S t u d e n t ) d e s densités es t imées . L e s différences s t a t i s t i q u e s d e

dens i tés calculées e n t r e r a d i e r e t p r o f o n d , d e j o u r e t d e n u i t , s o n t évaluées p a r d e s t e s t s n o n

p a r a m é t r i q u e s d e W i l c o x o n - M a n n - W h i t n e y (* : p < 0 , 0 5 ; ** : p < 0 , 0 1 ) .

of s tone loach within the ri f f le-pool sequences. Unfortunately, the small amount of individuals

caught per season meant that a correct analysis of cohorts in body length frequencies was not

poss ib le .

B r o w n t r o u t

Three age classes were identi f ied for brown trout by scal imetr ic analysis : young-o f - the-

year (0 +), one-year-o ld (1+) and older f ish (*1). Three-year-old t routs represented 21 % of '1

caught for all sampl ing dates. During the year, mean size-class for 0 + ranged from 28 m m after

Bull. Fr. Pêche Piscic. (1997) 346 : 573-588 — 579

0,4

J u n .

Oct .

J a n .

Apr.

I I I I I I

;

i 0,3 0,2

D e n s i t i e s i n p o o l ( i n d / m 2 )

0,1 0,2

D e n s i t i e s i n r i f f l e ( i n d / m 2 )

0,3 0,4

F i g u r e 3

D i e l a n d s e a s o n a l a g e - c l a s s e s d e n s i t i e s f o r b r o w n t r o u t s e s t i m a t e d i n r i f f l e a n d p o o l ( s e e F i g u r e 2

f o r e x p l a n a t i o n s ) .

F i g u r e 3

E s t i m a t i o n s journal ières e t saisonnières d e s densités d e t r u i t e s e n r a d i e r e t e n p r o f o n d p a r

c l a s s e s d 'âge ( v o i r F i g u r e 2 p o u r p l u s d e détails).

emergence to 85 m m in their f irst winter, f rom 103 m m to 138 m m for 1 + , and f rom 164 mm to

185 m m for M (Figure 4). Analysis of the seasonal evolut ion in fork length for individual ly marked

and recaptured 1* and »1 t routs showed that individual mean g rowth was high in summer and

s topped in fall and early winter except for one trout (Figure 5). Thereafter, mean body size

increased f rom winter to spr ing.

T h e t rbuf 'populat ion mainly compr ised 1 + fish f rom Jun-95 to Jan-96 (Figure 3). In 1995,

recrui tment was very low because of an except ional ly high f lood (one per hundred years) during

the winter 1994-95. However, the 1996 recrui tment was much better and consequently,

densi t ies of 0* were high in Apr-96 samples. For this per iod, soon after emergence, 0* were

signif icantly more numerous in riffle (p<0.05, W M W test). The 1* cohor t signif icantly preferred

pools f rom Jun r95 - to : Jan -96 (p<0.05, W M W test), whereas no preference between the t w o

habitat types was observed in Apr -96. Older t routs (M) showed the same tendencies as 1 + , even

if results were not statist ical ly signif icant. Signif icant diel di f ferences in 1* t rout distr ibut ions in


B u l l h e a d

Oct . 95 Jan. 96 Apr. 96

M i n n o w

Oct. 95 Jan. 96 Apr. i

S 0,5

80

™ r r r | g - i g i .60

' 4 0 + -

20 J_ o: _6.

— < > -

spawning

A p r . 96 Jun. 95 Oct. 95 Jan. 96 A p r . 96

80,5

200i

E150

sioo o u_

50

0

0*

B r o w n t r o u t

Oc t . 95 Jan.

emergence

Jun. 95 Oc t . 95 Jan. 96 A p r . 96

F i g u r e 4

S e a s o n a l v a r i a t i o n s i n a g e s t r u c t u r e f o r b u l l h e a d , m i n n o w a n d b r o w n t r o u t p o p u l a t i o n s ( d a r k

b a r s ) , a n d i n m e a n b o d y s i z e s f o r e a c h a g e c l a s s . V e r t i c a l l i n e s r e p r e s e n t s t a n d a r d d e v i a t i o n ( S D ) .

F i g u r e 4

V a r i a t i o n s saisonnières d e l a c o m p o s i t i o n d e s p o p u l a t i o n s d e c h a b o t s , d e v a i r o n s e t d e t r u i t e s

s e l o n l e s c l a s s e s d 'âge ( b a r r e s n o i r e s ) , e t d e s l o n g u e u r s m o y e n n e s p o u r c h a q u e c l a s s e d 'âge.

L e s t r a i t s v e r t i c a u x représentent l e s écar ts t y p e s a u t o u r d e l a m o y e n n e .

riffle were recorded in Jun-95 and Oc t -95 . For this per iod, almost all t routs were in pools at night

wh i le they used both riffles and pools during dayl ight. This was signif icant for 1 + , but '1 t routs

s h o w e d the same tempora l pat tern.

Analys is of individually marked trouts indicated that 49 % (Jun-95) and 61 % (Oct-95) of

f ish caugh t dur ing the first electrof ishing were recaptured two weeks later in the same riff le-pool

sequence (Figure 6). This r i f f le-pool fidelity d ropped in winter (22 % in Jan-96) and then

increased again in spr ing (30 % in Apr-96). This general pattern was also conf i rmed in riff le-pool

f idel i ty be tween seasons.


J u n . 95 Oct . 95 J a n . 9 6 Apr. 9 6

F i g u r e 5

S e a s o n a l v a r i a t i o n s i n f o r k l e n g t h f o r i n d i v i d u a l l y m a r k e d a n d r e c a p t u r e d t r o u t s . L i g h t l i n e s

r e p r e s e n t i n d i v i d u a l g r o w t h , h e a v y l i n e s m e a n v a l u e .

F i g u r e 5

V a r i a t i o n s saisonnières d e l a l o n g u e u r f o u r c h e d e s t r u i t e s m a r q u é e s e t recapturées l o r s d e s

différentes pêches . L e s t r a i t s f i n s représentent l a c r o i s s a n c e d e c h a q u e i n d i v i d u , l e s t r a i t s épais

l a c r o i s s a n c e m o y e n n e .

100

Jun. 95 Oct. 95 Jan. 96 Apr. 96

F i g u r e 6

P e r c e n t a g e o f i n d i v i d u a l l y m a r k e d a n d r e c a p t u r e d t r o u t s i n t h e s a m e r i f f l e - p o o l s e q u e n c e t w o

w e e k s a p a r t f o r e a c h s e a s o n ( d a r k b a r s ) , a n d b e t w e e n s e a s o n s ( h o r i z o n t a l l i n e s ) .

F i g u r e 6

P o u r c e n t a g e d e t r u i t e s m a r q u é e s e t recapturées d a n s l a m ê m e s é q u e n c e r a d i e r - p r o f o n d à d e u x

s e m a i n e s d ' i n t e r v a l l e ( b a r r e s n o i r e s ) , e t d ' u n e s a i s o n à l ' a u t r e ( t r a i t s h o r i z o n t a u x ) .


D I S C U S S I O N

Bul lhead, minnow, b rown trout and stone loach are widely d ist r ibuted along the

longi tud ina l axis in s t reams in Bri t tany (OBERDORFF and PORCHER, 1992). In the Scorff river

bas in , sympat r i c populat ions of these species can occur in the main river (BAGLINIÈRE and

ARRIBE-MOUTOUNET, 1985) and in tributaries, where they are the predominant species with

eel (BAGLINIÈRE, 1979). Some field and experimental studies have been concentrated on the

potent ia l over lap of d iets and/or habi tat requirements (MAITLAND, 1 9 6 5 ; M A N N and ORR,

1 9 6 9 ; LIEN, 1981 ; NEVEU, 1981 ; BALTZ et al., 1 9 8 2 ; WELTON et al., 1 9 8 3 ; GLOVA, 1 9 8 7 ;

B R O W N , 1991), but little is known about the tempora l aspect of habitat use. On a seasonal

scale, habi tat shifts are closely related to the life history of species, like ontogenet ic changes in

habi ta t requi rements (ELLIOTT, 1986 ; BAGLINIÈRE era/ . , 1989 ; BALTZ et al., 1991 ; SEMPESKI

and G A U D I N , 1995 ; KOCIK and TAYLOR, 1996), spawning (BAGLINIÈRE era/ . , 1987 ; MEYERS

et al., 1992) and overwinter ing migrat ion (CUNJAK and POWER, 1986 ; SWALES ef a/., 1986 ;

B R O W N and MACKAY, 1995), whereas diel habi tat shifts usually cor respond to circadian

rhy thms of rest ing and feeding act iv i t ies (CAMPBELL and NEUNER, 1985 ; KWAK et al., 1992 ;

HEGGENES e ra / . , 1993 ; ROUSSEL and BARDONNET, 1996).

S e a s o n a l c h a n g e s i n d e n s i t i e s

For bul lhead, t he decrease in win ter did not affect the structure of the populat ion and the

respect ive percentages of each age c lass. The densi ty of 1* and older individuals in April 1996

is simi lar to those observed in June 1995. This w o u l d indicate that a high winter mortal i ty (more

than 5 0 % ) affects the bul lhead populat ion. In April 1996, the 0 + cohor t is still missing in

e lect rof ish ing samples, but their catchabi l i ty is probably null because of a total body length of

less than 10 m m after hatching (SMYLY, 1957). In trout, the decrease recorded in January for

the 1994 cohor t (1*) can be expla ined by the general pattern of upstream spawning migrat ion

(which inc ludes 1* mature individuals), as descr ibed by BAGLINIÈRE ef al. (1987). Thereafter,

there is a smal l increase in Apri l 1996 for the 1995 cohort densi ty (the new 1 + cohort). This

re-equi l ibr ium in 1 + densi t ies in the low part of t he brook cou ld be the result of a downst ream

movemen t f rom the upper part of the brook initiated in the previous au tumn by 0 + , as studied

by BAGLINIÈRE ef al. (1989) in another tributary of the Scorff river. For minnow, a winter

decrease w a s also observed , wi th 0 + individuals absent f rom electrof ishing samples. Accord ing

to d iv ing observat ions in Kerlégan pools (ROUSSEL and BARDONNET, unpubl ished data),

0 + m innow may exhibit a s t rong winter concealment in carex f ine roots a long pool margins. This

makes ca tch ing them by electrof ishing very difficult, because of their quiescent behaviour and

the low water temperature. Thereafter, the increase in densit ies in Apri l 1996 is related to the

re -appearance of 0* in samples . Dur ing the breeding per iod, very few individuals were caught in

June 1995. M innow is a l i thophil spec ies that breeds on gravel bars (BALON, 1975). Such

spawn ing areas are character ized by shal low, swift waters (PONCIN, 1996). Because of the high

dens i ty of spawn ing shoals, their space partit ion on spawning areas is very patchy and possibly

none of t h e m w a s present in the samp led areas. For loach, the decrease in densi ty in January

and Apri l canno t be expla ined by popula t ion dynamics since densit ies were too low to identify

age c lasses.

H a b i t a t t y p e c h o i c e

Minnow

Accord ing to the l i terature, habitat preferences in European minnow depend on stream

size. On a 15 m w id th s tat ion in the Scorff river, BAGLINIÈRE and ARRIBE-MOUTOUNET (1985)

observed that densi t ies of m innow in October were the highest in shal low and lotie habitats

(about 20 c m dep th and f rom 20 to 40 cm/s). Under similar condi t ions in the river Nivelle

(France), NEVEU (1981) hypothes ized that they avo ided the deepest habi tats (more than 50 cm

depth) because of the presence of predators. The increased use of shal low habitat by minnow

under prédat ion risk has been recently pointed ou t under exper imental cond i t ions (EKLÔV ef al.,

1994). However, results on smal l s t reams (less than 6 m width) showed that minnow usually

inhabi t the deepest (more than 30 cm) lentic areas (MAITLAND, 1 9 6 5 ; JONES, 1 9 7 5 ;


BAGLINIÈRE, 1979). This corresponds to a preference for pools, as observed in Kerlégan brook

for all life s tages. The minnow's affinity for cover and shelter st ructures, especial ly for coarse

w o o d y debr is (NEVEU, 1981), macrophytes (LIEN, 1 9 8 1 ' ; MASTRORILLO ef al., 1996) o r stony

bo t tom substrate (JACOBSEN, 1 9 7 9 ; BAGLINIÈRE and ARRIBE-MOUTOUNET, 1985), has

often been reported by authors. A long the pool margin in the Kerlégan brook, over hanging

carex provides a large amount of overhead cover and shelter (underbank, f ine roots).

Sfone loach

As many loaches were found in pools as in riffles, except in June. This w ide distr ibut ion

in different habi tat types was also noted by MAITLAND (1965) and ZWEIMÛLLER (1995) in

lowland brooks, even if MAITLAND not iced a sl ight preference for pools. However, JONES

(1975) observed a marked preference for riffle or run (depending on the stream studied), with in

all cases the lowest densit ies in pools. Cont rad ic t ions in the literature about loach habitat use

are c o m m o n and diff icult to clarify. The s tone loach is a very discreet species and little is known

about its habitat requirements. Despite its s t rong associat ion wi th the bo t tom as a benthic

species, SMYLY (1955) d id not f ind any preference for sandy, gravelly and m u d d y bo t toms. The

use of shelter dur ing daylight has been descr ibed by BURDEYRON (1981), and s tone loach d id

not seem to need any speci f ic structures to exhibit th is behaviour s ince they are able to bury

themselves in the sandy bo t tom. BURDEYRON (1981) observed a seasonal d isplacement

towards areas wi th aquat ic macrophytes in spr ing and depar ture at the beginning of fal l , and

suggested that f ish moved in spr ing to reproduce on macrophytes . This cou ld explain why in

June they were more numerous in riffle than in poo l , s ince Ranunculus spp mainly developed

on riffles (Table I).

Bullhead

Bul lheads, like freshwater Cottidae in general , are morphological ly adapted to hold a

posi t ion on the bo t tom in high velocit ies wi thout energy constra ints (FACEY and GROSSMAN,

1992). Depend ing on the study, they inhabi t e i ther fas t - f low ing (BAGLINIÈRE, 1 9 7 9 ;

BAGLINIÈRE and ARRIBE-MOUTOUNET, 1 9 8 5 ; COPP, 1992) or s low- f low ing habi tats

(GAUDIN, 1981 ; GAUDIN and CAILLÈRE, 1990). In October, a lmost all ( 9 0 % ) young-o f - the-

year individuals were electrof ished in riffles. Riffles in Kerlégan brook may be attractive to

bul lhead for t w o different reasons : the use of unembedded cobb les as shelter is well known in

f reshwater Cottidae (BROWN,.1991 ; GREENBERG and STILES, 1993 ; HARO and BRUSVEN,

1994) and stone shelters are in l imited number in poo ls (Table I). The other reason may be

t rophic : indeed, PETTY and GROSSMAN (1996) repor ted that patchy distr ibut ion in mot t led

sculp ins (Cottus bairdi Girard) in large st reams was constant ly related to prey abundance. A

similar patchy dist r ibut ion cou ld cor respond to riffle habi tat in the Kerlégan brook, s ince riffles

are known to be higher benthos-produc ing areas (LOGAN and BROOKER, 1983 ; BROWN and

BRUSSOCK, 1991). The use of riffle was more p ronounced in 0 + f ish, even if it decreased

through the seasons to reach 70 % in Apri l , wh i ch cor responded to the total populat ion

propor t ion in riffle. GREENBERG (1991) reported that small benthic f ish avoided deep habitats

because of a higher prédat ion risk. As they grow, bul lheads become less and less vulnerable t o

f ish prédat ion, and at the same t ime are able to eat larger prey (ANDREASSON, 1971). A shift

in feeding habits cou ld lead them to explore deeper habi tats. It is then possible that the slight

seasonal decrease in preference f rom riffle nursery areas towards pool habitats may result from

a progressive d rop in prédat ion risk associated wi th a change in feeding mot ivat ions as the f ish

grow. Trophic capaci t ies or the number of s tone shelters cou ld have f ixed the upper density in

the pool to about one individual per square metre.

Brown trout

The new 0 + cohor t of b rown trout also preferred riffle to poo l . As hypothesized for

bul lhead, young 0* might avoid deep areas because of the p isc ivorous f ish prédat ion risk

(BARDONNET and HELAND, 1994). On the contrary, 1 + and older individuals were more

numerous in pool habi tats for most of the t ime. This spat ial inter-cohort segregat ion along the

water dep th gradient has already been descr ibed for b rown trout in other s tudies (BOHLIN,

Bull. Fr. PêchePiscic. (1997)m:573-588 — 5 8 4 —

1977 ; EGGLISHAW and SHACKLEY, 1982 ; BAGLINIÈRE and ARRIBE-MOUTOUNET, 1985). A shift f r om 0 + riffle habitats towards deeper areas is establ ished through the seasons, and can be ini t iated f rom the beginning of summer (KOCIK and TAYLOR, 1996) or in winter (ELLIOTT, 1986). It cou ld be related t o ontogenet ic changes in habitat requirements. Accord ing to HARVEY and STEWART (1991), as they grow, juveni le brown trouts may become more exposed to diving or wad ing predators in shal low riffle, and so need t o seek shelter in deeper pool habitats. However, habi ta t change can a lso co r respond t o reaching a cri t ical size wh ich may limit compet i t ion or even prédat ion f rom older t routs.

The only observat ion of a diel use of the riff le-pool sequence came f rom 1 + and older t routs . Dur ing the growing season (June-October) when the highest r i f f le-pool f idelit ies were recorded for individual ly marked t routs, they exhibi ted an increased use of riffle dur ing dayl ight. A similar movemen t f rom pool to riffle during dayl ight has already been shown under exper imenta l condi t ions on 1 + t routs and related t o feeding (ROUSSEL and BARDONNET, 1995). BRIDCUT and GILLER (1993) observed that trouts marked in riffles showed more movements f rom these habitats than t routs marked in pools, indicat ing that riffles are occasional rather than regular habi tats. Habitat cho ice wi th in the riffle-pool sequence could then be regarded as a t rade-of f be tween potent ia l energy intake and prédat ion risk (FAUSCH, 1984 ; METCALFE ef al., 1987), s ince faster water in riffles is supposed to provide better drift feeding condi t ions than pools , but is a lso cons idered as a more risky area.

T h e f u n c t i o n a l r o l e o f t h e r i f f l e - p o o l s e q u e n c e

At the riff le-pool scale, two types of temporal changes were identif ied. Stone loach, 0* trout and bul lhead represented examples of seasonal changes, probably l inked wi th a movement to join the spawn ing si te for loach and wi th ontogenesis for t routs and sculp ins. The other tempora l change was diel and concerned the increased use of riffle by 1 + and older t routs dur ing dayl ight . These results conf i rm that f ish habitat management in sa lmonid st reams should not be assessed w i thou t consider ing the tempora l dimension of fish habitat requirements.

The r i f f le-pool sequence is an important habitat feature in sa lmonid st reams providing spat ia l heterogenei ty to suppor t f reshwater fish deve lopment at different biological levels. At the f ish c o m m u n i t y level, it may enhance biodiversity, al lowing species wi th different habitat requi rements to cohabi t . A t the popu la t ion level, it authorizes age classes exhib i t ing different habi tat preferences t o deve lop in adjo in ing habitat types. Lastly, at the individual level, it a l lows the express ion of daily behaviour w i th pools providing nocturnal resting areas for t rout feeding in riffle. For these reasons, more at tent ion should be paid to protect ing the ri f f le-pool sequences and spat ia l heterogenei ty on channel hydraulics, since habitat diversity loss appears to be the major cause of long- term al terat ions in f ish populat ions (NIEMI ef al., 1990). Accord ing to the l i terature, the natural dynamics of instream coarse woody debris plays an impor tant role in hydraul ic p rocesses assoc ia ted w i th riff le-pool format ion and stabil ization of the channel in dif ferent t ypes of streams, including lowland rivers (GREGORY and DAVIS, 1992 ; GREGORY ef al., 1992 ; LANGFORD, 1996). Thus, the removal of instream w o o d y debr is, wh ich is a usual pract ice in French st ream management , would need to be reconsidered owing to the harmful consequences this cus tom has on the natural hydraul ic processes that are closely related to the r i f f le-pool sequence format ion.

A C K N O W L E D G E M E N T S

We wou ld like to thank N. JEANNOT, F. LEFEVRE, F. MARCHAND and many students for their he lp dur ing the f ield exper iments . We are also grateful to J.Y. MOËLO and to the Scorff Angl ing Assoc ia t ion for electrof ishing and exper iments facil it ies. This work was partially f inanced by the French Consei l Supérieur de la Pêche.

Bull. Fr. Pêche Piscic. (1997) 346:573-588 — 585 —

R E F E R E N C E S

A N D R E A S S O N S , 1 9 7 1 . Feed ing habi ts of a scu lp in (Cotius gobio L , P isces) popu la t ion .

Inst. Freshw. R e s , Dro t tn ingho lm, repor t n° 5 1 , 3 0 p.

B A G L I N I È R E J . L , 1979. Les pr inc ipales popula t ions de po issons sur une rivière à sa lmon idés

de B re tagne -Sud , le Scorff. Cybium 3, 5 3 - 7 4 .

B A G L I N I È R E J . L , A R R I B E - M O U T O U N E T D , 1985. Micro- répar t i t ion des popu la t ions d e

t ru i te c o m m u n e (Salmo trutta), de juvén i les de s a u m o n at lant ique (Salmo salar) et

d e s au t r es e s p è c e s p r é s e n t e s d a n s la pa r t i e hau te du Scor f f (B re tagne ) .

Hydrobiologia, 120, 229 -239 .

B A G L I N I È R E J . L , M A I S S E G , L E B A I L P.Y, P R E V O S T E , 1987 . D y n a m i q u e de la

popu la t ion de t ru i te c o m m u n e (Salmo trutta L.) d 'un ru isseau b re ton (France) . Il -

Les gén i teurs migrants . Acta Oecol., Oecol. Appt., 8, 2 0 1 - 2 1 5 .

B A G L I N I È R E J . L , M A I S S E G , L E B A I L R Y , N I H O U A R N A , 1989. Popula t ion dynamics of

b rown trout , Salmo trutta L , in a t r ibu tary in Br i t tany (France) : s p a w n i n g and

juven i les . J. Fish Biol., 34, 97 -110 .

B A L O N E . K , 1975. Reproduc t ive gu i lds of f i shes : a p roposa l and def in i t ion. Can. J. Fish.

Aquat. Sci., 32, 821 -864 .

BALTZ D . M , M O Y L E R B , K N I G H T N . J , 1982 . Compet i t i ve in teract ions be tween benth ic

s t ream f ishes, riffle scu lp in , Cottus gulosus, and specke l dace , Rhinichthys osculus.

Can. J. Fish. Aquat. Sci., 39, 1 5 0 2 - 1 5 1 1 .

BALTZ D . M , V O N D R A C E K B , B R O W N L.R., M O Y L E R B , 1 9 9 1 . Seasona l changes in

microhabi ta t se lect ion by ra inbow t rout in a sma l l s t r eam. Trans. Am. Fish. Soc, 120,

166-176 .

B A R D O N N E T A , H E L A N D M , 1994 . T h e in f luence of potent ia l p redators on the habitat

p re fe renda of emerg ing b rown t rout . J. Fish Biol., 45 (suppl. A), 131 -142 .

BHATTACHARYA C O , 1967. A s imp le m e t h o d of resolut ion of a d is t r ibut ion into gauss ian

componen t s . Biometrics, 25, 115 -135 .

B I S S O N P.A., N I E L S E N J . L , P A L M A S O N R . A , G R O V E L E , 1982 . A sys tem of naming

habi tat t ypes in smal l s t reams , w i th examp les of habi tat ut i l izat ion by sa lmon ids

dur ing low st reamf low. In A R M A N T R O U T N.B., Acqu is i t ion a n d ut i l izat ion of aquat ic

habi tat inventory in format ion , 6 2 - 7 3 , A m e r i c a n F isher ies Society, W e s t e r n Div is ion,

Be thesda .

B I S S O N R A , M O N T G O M E R Y D . R , 1996 . Val ley s e g m e n t s , s t ream reaches and channe l

uni ts. In H A U E R F R , L A M B E R T I G.A., M e t h o d s in s t ream ecology, 2 3 - 5 2 , Academ ic

Press, London .

B O H L I N T , 1977. Habi tat se lec t ion a n d in tercohor t compet i t ion of juven i le sea- t rou t Salmo

trutta. Oikos, 29, 112-117 .

B R I D C U T E . E , G I L L E R R S , 1993. M o v e m e n t a n d s i te f idel i ty in young b rown t rou t Salmo

trutta popu la t ions in a sou the rn Ir ish s t r e a m . J. Fish Biol., 43, 889 -899 .

B R O W N L . R , 1 9 9 1 . Di f ferences in habi ta t cho ice and behav iour a m o n g th ree spec ies of

scu lp in (Cottus) in art i f ic ial s t r e a m channe l s . Copeia, 3, 8 1 0 - 8 1 9 .

B R O W N A.V., B R U S S O C K P.P., 1 9 9 1 . C o m p a r i s o n s of benth ic inver tebrates b e t w e e n riffles

a n d poo ls . Hydrobiologia, 220, 99 -108 .

B R O W N R . S , M A C K A Y W . C , 1995. Fall and w in ter m o v e m e n t s of and habi tat use by

cut throat t rout in the R a m river, A lbe r ta . Trans. Am. Fish. Soc, 124, 8 7 3 - 8 8 5 .

B R Y A N T M.D., W R I G H T B . E , D A V I E S . B . J , 1992 . App l i ca t ion of a h ierarch ica l habitat unit

c lass i f icat ion sys tem : s t ream habi tat a n d sa lmon id d is t r ibut ion in W a r d creek,

Sou theas t A laska . Pacif ic Nor thwes t Research Stat ion, Research No te P N W - R N - 5 0 8 .

B U R D E Y R O N H , 1 9 8 1 . Act iv i tés r y thm iques c o m p o r t e m e n t a l e s d 'un po i sson benth ique,


la loche , Noemacheilus barbatulus L. (Cobitidae), dans son mi l ieu naturel et en

laborato i re . P h . D. thes is , Univers i ty of Lyon (France) , 2 8 4 p.

C A M P B E L L R.F., N E U N E R R.G., 1985. Seasona l a n d d iurna l shifts in habi tat ut i l ized by

res iden t ra inbow t rout (Salmo gairdneri) obse rved in wes te rn Wash ing ton c a s c a d e

m o u n t a i n s t reams . In O L S O N and W H I T E , Proceed ings of S y m p o s i u m on smal l

hyd ropower and f isher ies , 38 -49 , Amer ican F isher ies Society, Denver.

C A R L E F.L., S T R U B M.R., 1978. A new method for es t imat ing popu la t ion size f rom remova l

da ta . Biometrics, 34, 6 2 1 - 6 3 0 .

C O P P G . H . , 1992 . A n empi r i ca l m o d e l for pred ic t ing microhabi ta t of 0 + juven i le f ishes in a

l ow land river ca t chmen t . Oecologia, 91, 338 -345 .

C U N J A K R.A., P O W E R G. , 1986 . Win te r habitat ut i l izat ion by s t ream res ident b rook t rout

(Salvelinus fontinalis) and b r o w n trout (Salmo trutta). Can. J. Fish. Aquat. Sci., 43,

1 9 7 0 - 1 9 8 1 .

D E L U R Y D.B., 1 9 5 1 . O n the p lann ing of exper iments for the est imat ion of f ish popu la t ions .

J. Fish. Res. Board. Can., 8, 281-307.

E G G L I S H A W H.J., S H A C K L E Y R E . , 1982. In f luence of water dep th on d ispers ion of

j uven i le sa lmon ids , Salmo salar L. and Salmo trutta L., in a Scot t ish s t ream. J. Fish

Biol., 21, 141-155.

E K L Ô V A . G . , G R E E N B E R G L.A., K R I S T I A N S E N H., 1994. T h e effect of dep th on the

in te rac t ion be tween perch (Perca fluviatilis) and m innow (Phoxinus phoxinus).

Ecol. Freshw. Fish, 3, 1-8.

E L L I O T T J .M . , 1986. Spat ia l d is t r ibut ion and behav ioura l movemen ts of migra tory t rout

Salmo trutta in a Lake Distr ict s t ream. J. Anim. Ecol., 55, 907 -922 .

FACEY D.E., G R O S S M A N G.D., 1992. T h e relationship between water velocity, energet ic costs

a n d mic rohab i ta t use in four Nor th Amer ican s t ream f ishes. Hydrobiologia, 239, 1-6.

F A U S C H K.D., 1984 . Prof i table s t r eam posi t ions for sa lmon ids : relat ing speci f ic g rowth rate

to net ene rgy ga in . Can. J. Zool., 62, 4 4 1 - 4 5 1 .

F R I S S E L L O A . , L ISS W.J . , W A R R E N C E . , H A R L E Y M.D., 1986. A h ierarchica l f r amework

for s t ream habitat classif icat ion : viewing s t reams in a watershed context. Env. Manage.,

10, 199-214 .

G A U D I N P., 1 9 8 1 . Eco-éthologie d 'un poisson benth ique, le chabot, Cottus gobio L. (Cottidae) :

d is t r ibu t ion , a l imenta t ion et rapports avec la trui te, Salmo trutta L. Ph . D. thes is ,

Un ivers i t y of Lyon (France) , 178 p.

G A U D I N P., C A I L L È R E L , 1990. Microdis t r ibut ion of Cottus gobio L. and f ry of Salmo trutta

L. in a f irst o rder s t ream. Pol. Arch. Hydrobiol., 37, 81 -93 .

G I B S O N R.J., S T R A N S B U R Y D.E., W H A L E N R.R., H ILL IER K.G., 1993. Relat ive habi ta t

use , a n d inter-speci f ic a n d intra-specif ic compet i t ion of b rook trout (Salvelinus

fontinalis) and juven i le At lant ic sa lmon (Salmo salar) in s o m e Newfound land r ivers.

Can. Spe. Publ. Fish. Aquat. Sci., 118, 53 -69 .

G L O V A G.J. , 1987. C o m p a r i s o n of a l lopatr ic cut throat t rout s tocks with those sympat r i c wi th

s a l m o n and scu lp ins in sma l l s t reams. Environ. Biol. Fishes, 20, 275 -284 .

G L O V A G.J. , S A G A R P.M., 1993. A fur ther assessmen t of t rophic and spat ia l in ter- re lat ions

of ga lax i ids a n d sa lmon ids in New Zea land . Ecol. Freshw. Fish, 2, 132-140 .

G R E E N B E R G L.A., 1 9 9 1 . Habi ta t use a n d feeding behav iour of th i r teen spec ies of benth ic

s t r e a m f ishes. Environ. Biol. Fish., 31, 3 8 9 - 4 0 1 .

G R E E N B E R G L.A., S T I L E S R.A., 1993. A desc r ip t i ve a n d expe r imen ta l s tudy of

m ic rohab i ta t use by young-of - the-year benth ic s t ream f ishes. Ecol. Freshw. Fish, 2,

4 0 - 4 9 .


G R E G O R Y K . J , DAVIS R . J , 1992 . C o a r s e w o o d y debr is in s t r eam-channe l s in relat ion to

river channe l m a n a g e m e n t in w o o d l a n d areas . Regul. Riv., 9, 35 -43 .

G R E G O R Y K . J , DAVIS R . J , T O O T H S , 1992 . Spat ia l d is t r ibut ion of coa rse w o o d y debr is

d a m s in the Lyming ton Bas in , Hampsh i re , UK. Geomorphology, 6, 2 0 7 - 2 2 4 .

G R I F F I T H J.S. , 1972 . C o m p a r a t i v e behav iou r a n d habi ta t ut i l izat ion of b rook t rou t

(Salvelinus fontinalis) and cu t th roat t rout (Salmo clarki) in sma l l s t r eams in Nor thern

Idaho. J. Fish. Res. Board. Can., 29, 2 6 5 - 2 7 3 .

H A R O R . J , B R U S V E N M.A. , 1 9 9 4 . E f fec ts of c o b b l e e m b e d d e d n e s s on t h e

microdis t r ibut ion of the scu lp in Cottus beldingi a n d its s tonef ly prey. Great Basin

Naturalist, 54, 64 -70 .

H A R V E Y B.C., S T E W A R T A . J , 1 9 9 1 . Fish size and habi tat dep th re la t ionsh ips in headwater

s t reams. Oecologia, 87, 3 3 6 - 3 4 2 .

H A U R Y J , B A G L I N I È R E J . L , 1996 . Les macrophy tes , fac teur s t ruc turan t de l 'habitat

p isc ico le en r iv ière à sa lmon idés . E tude de mic rorépar t i t ion sur un sec teur végéta l isé

du Scorf f (B re tagne-Sud) . Cybium, 20 (suppl. 3), 111 -127 .

H A W K I N S C P , K E R S H N E R J . L , B I S S O N P.A., BRYANT M . D , D E C K E R L . M , G R E G O R Y

S.V , M c C U L L O U G H D . A , O V E R T O N C . K , R E E V E S G . H , S T E E D M A N R . J ,

Y O U N G M . K , 1993. A h ierarch ica l app roach to c lass i fy ing s t r e a m habi tat features.

Fisheries, 18, 3 -12 .

H E G G E N E S J , K R O G O . M , L I N D A S O.R., D O K K J . G , B R E M N E S T , 1993 . Homeosta t ic

behav ioura l responses in a chang ing env i ronmen t : b r o w n t rou t (Salmo trutta)

b e c o m e nocturna l du r ing winter . J. Anim. Ecol., 62, 295 -308 .

J A C O B S E N O . J , 1979 . Subs t ra te p re fe rence in the m innow (Phoxinus phoxinus L.). Pol.

Arch. Hydrobiol., 26, 3 7 1 - 3 7 8 .

J O N E S A . N , 1975. A p re l im inary s tudy of f ish segrega t ion in s a l m o n s p a w n i n g s t reams.

J. Fish. Biol., 7, 95 -104 .

J O W E T T I . G , 1993. A m e t h o d for ob ject ive ly ident i fy ing poo l , run a n d riffle habi ta ts f rom

physical measu remen ts . N. Z. J. Mar. Freshw. Res., 27, 241 -248 .

K O C I K J.F.-, T A Y L O R W . W , 1996. Effect of juven i le s t ee lhead on juven i le b r o w n t rou t habitat

use in a low-gradient Grea t Lakes tr ibutary. Trans. Am. Fish. S o c , 125, 244-252 .

K W A K T . J , W I L E Y M . J , O S B O R N E L . L , L A R I M O R E R . W , 1992 . App l i ca t ion of diel feeding

chrono logy to habi tat sui tabi l i ty ana lys is of w a r m water s t r eam f ishes. Can. J. Fish.

Aquat. Sci., 49, 1 4 1 7 - 1 4 3 0 .

L A N G F O R D T , 1996 . Eco log ica l aspec ts of new forest s t reams , d ra in ing one of Britain's

un ique a reas . Freshwater Forum, 6, 2 -38 .

L IEN L , 1 9 8 1 . B io logy of the m i n n o w Phoxinus phoxinus a n d its in teract ions w i th brown

trout Salmo trutta in O v r e He imda lsva tn , Norway. Holarctic Ecol., 4, 191 -200 .

L O G A N P, B R O O K E R M.P , 1983 . T h e macro inver tebra te f aunas of r i f f les a n d poo ls . Water

Res., 17, 263 -270 .

M A I T L A N D R S , 1965. T h e feed ing re la t ionsh ips of sa lmon , t rout , m innows , s tone loach and

th ree-sp ihed s t icke lbacks in the r iver Endr ick , Sco t land . J. Anim. Ecol., 34, 109-133.

M A L A V O I J . R , 1989. Typo log ie d e s fac iès d 'écou lemen t o u uni tés m o r p h o d y n a m i q u e s des

cours d 'eau à haute énerg ie . Bull. Fr. Pêche Piscic., 315, 189 -210 .

M A N N R . H . K , O R R D . R . O , 1 9 6 9 : A pre l im inary s tudy of t he feed ing re la t ionships of fish in

a hard-water a n d a sof t -water s t r e a m in sou the rn E n g l a n d . J. Fish Biol., 1, 31-44.

M A S T R O R I L L O S , DAUBA F, B E L A U D A , 1996. Uti l isat ion des microhab i ta ts par le vairon,

le gou jon et la loche f ranche d a n s t ro is r iv ières d u sud -oues t d e la France. Ann.

Limnol., 32, 185-195 .


M E T C A L F E N.B., H U N T I N G F O R D F.A., T H O R P E J.E. , 1987 . T h e in f luence of prédat ion

r isk o n the feed ing mot iva t ion and foraging st rategy of juven i le At lant ic sa lmon . Anim.

Behav., 35, 9 0 1 - 9 1 1 .

M E Y E R S L.S., T H U E M L E R T.F., KORNELY G.W., 1992. Seasona l movemen ts of b rown

t rout in nor th -eas t W i s c o n s i n . North Am. J. Fish. Manage., 12, 4 3 3 - 4 4 1 .

N E V E U A. , 1 9 8 1 . Dens i té et microrépar t i t ion d e s d i f férentes espèces d e po issons dans la

Basse-Nivel le , petit f leuve cô t i e rdes Pyrénées-At lant iques. Bull. Fr. Piscic., 280, 86-102.

N I E M I G.J . , D E V O R E P., D E T E N B E C K N., TAYLOR D., L IMA A., PASTOR J . , Y O U N T J.D.,

N A I M A N R., 1990 . O v e r v i e w of case s tud ies on recovery of aquat ic sys tems f rom

d i s tu rbance . Env. Manage., 14, 571-587 .

O B E R D O R F F T., P O R C H E R J .R, 1992 . Fish assemb lage s t ructure in Br i t tany s t reams

(France) . Aquat. Living Resour., 5, 215-223.

P E T T Y J.T., G R O S S M A N G.D., 1996 . Patch se lect ion by mot t led sculp in (P isces : Cottidae)

in a sou the rn Appa lach ian s t r eam. Freshw. Biol., 35, 261 -276 .

P O N C I N P., 1996. Rep roduc t i on chez nos po issons . Fédéra t ion spor t ive des pêcheurs

f r a n c o p h o n e s de Be lg ique A S B L , 80 p.

R A B E N I C F . , J A C O B S O N R.B., 1993 . The impor tance of f luvial hydraul ics to f ish habi tat

res tora t ion in low-grad ient al luvial s t reams. Freshw. Biol., 29, 211 -220 .

R O P E R B.B., S C A R N E C C H I A D.L., 1995. Observer var iabi l i ty in c lassi fy ing habi tat types in

s t r e a m surveys . North Am. J. Fish. Manage., 15, 49 -53 .

R O U S S E L J .M . , B A R D O N N E T A., 1995. Activi té nyc théméra le et ut i l isat ion d e la séquence

rad ier -pro fond par les t ru i te l les d'un a n (Salmo trutta L.). Bull. Fr. Pêche Piscic,

337/338/339, 2 2 1 - 2 3 0 .

R O U S S E L J .M . , B A R D O N N E T A., 1996. Changemen ts d 'habi ta t de la trui te (Salmo trutta) et du chabo t (Cottus gobio) au cours du nyc thémère : app roches mul t ivar iées à

d i f fé ren tes éche l les spat ia les . Cybium, 20 (suppl. 3), 43 -53 .

S E M P E S K I R, G A U D I N P., 1995 . Size-related changes in die l d ist r ibut ion of y o u n g grayl ing (Thymallus thymallus). Can. J. Fish. Aquat. Sci., 52, 1842-1848 .

S M Y L Y W.J.P., 1955. O n the b io logy of the stone loach Nemacheilus barbatula (L.). J. Anim.

Ecol., 24, 167-186 .

S M Y L Y W.J .R , 1957. T h e l i fe-history of the Bu l lhead or mi l ler 's t h u m b (Cottus gobio L ) .

Proc. Zool. Soc. Lond., 128, 431-453.

S W A L E S S., LAUZ IER B., L E V I N G S C D . , 1986 . Win te r habi tat pre ferences of juven i le

s a l m o n i d s in two inter ior r ivers in Brit ish Co lumb ia . Can. J. Zool., 64, 1506-1514 .

V A N D E V E N T E R J.S. , PLATTS S., 1989. M ic rocompute r so f tware sys tem for genera t ing

popu la t i on stat is t ics f r om electrof ishing data - user 's gu ide for Microf ish 3.0. G e n .

Tech . Rep. INT-254, O g d e n , UT : U.S. Depa r tmen t of agr icu l ture, Forest Serv ice ,

In te r -mounta in R e s e a r c h Sta t ion , 29 p.

W E L T O N J.S. , M ILLS C.A., R E N D E L E.L., 1983. Food and habi tat par t i t ion ing in two smal l

ben th ic f ishes, Nemacheilus barbatulus L. and Cottus gobio L. Arch. Hydrobiol., 97,

4 3 4 - 4 5 4 .

Z W E I M Ù L L E R I., 1995 . M ic rohab i ta t use by t w o smal l benth ic s t ream f ish in a second order

s t r e a m . Hydrobiologia, 303, 125-137.

Documents

Diel and seasonal patterns of habitat use by fish in a natural