waders and their estuarine food supplies - Vlaams Instituut voor de ...

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$Wetenschap - \Nijverheid- Handel$

20 • -60 -40 -20 0 +20 +40 deviation Irom mean body weight (%) BURROWING AND FEEDING IN NEREIS 7. MMEfl +60 Fig. 6. Nereis diversicolor. Burrow depth (mean ± SEi of worms ol 10 (7 to 141 cm as a function of body condilion in 4 seasons (n = 2247): sites with different clay contenl are laken together. As in I and 5 a correction was made io adjust for the si/e effect on deplh. See Table 5 for statistical analysis. Burrow depth in relation to season and temperature There was a great difference in burrow depth between summer and winter for all si/e classes (Fig. 3). Figure 7 shows the burrow depth of Nereis of 10 em over a number of years. There is a large similarity between ihc years: burrow depth was maximal in January or Table 5. Results ol a 2 way analysis ol variance lo lesi the ell body condition and season on burrow depth (n = 2247: same dala as lig. 61. Soun e "i variation A'-. '; Main effects season condilion T\vo-way interaction 29.5 27.1 3.5 (1.0 (MX) I 0.001 0.001 0.242 February, followed by a decrease of 2 cm per month until the minimal depth was reached in June or July. Then, in late summer, burrow depth gradually began to increase again with an acceleration after October. Variations in burrow depth throughout the year cor respond with day length, but there is a betier correla tion between depth and sea water temperature (Fig. 71. Figure 8 shows a curvilinear relationship between sea water temperature and burrow depth. Burrow depth appears to depend on temperature, independent of the time of year; an analysis of covariance (not shown) confirmed this. All burrows were found in ihc upper 30 cm. even in winter, and since a core sampler of 40 em was used, the possibility of deeper burrow s was eliminated. The fact that burrow depth correlates well with sea water tem perature (Figs. 7 and 8) suggests that low temperatures stimulate Nereis to deepen their burrows. The only lime we observed remarkable digging activity by Kij*. 7. Nereis diversicolor. Seasonal variation m burrow deplh (mean ± SI worms of Idem (7 to 14 cm. with transformation as in l-'ig. 4|. living in mud (clay content £ '>' ; I. Sea water temperatures on Ihe sampling dales are laken from Ihe series ol daily measurements ol RijkswakTslaal al Holwerd. N J M M J S N 308
8 10 I 12 JZ 5. -g 1*» •e o i 16 .0 18 u o 20 . I 0 / o o°c A o A / * »»/ *• .7. • BURROWING AND FEEDING IN NEREIS A AAA A A A •***/?" o A A A A A A 6 A A spring A summer • autumn O winter 1 4 _l 8 1 12 L 16 1 20 sea water temperature (°C) Fig. 8. Nereis diversicolor. Burrow deplh of woims of ID cm. In me in mud (clay content > b'.V ). a- a function of sea water temperature. given separatelv lor ihe 4 seasons (61 sampling days Irom 1980 to 1985). line based on second degree polynomial (R 2 = 77 p
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WADERS AND THEIR ESTUARINE FOOD SUP
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plia^ohi. WADERS AND THEIR ESTUARI
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Waders and their estuarine food sup
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WADERS AND THEIR ESTUARINE FOOD SUP
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figuren: Dick Visser omslagfoto: Ja
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15 Versatility of male curlews (Num
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That science is making progress, ma
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INTRODUCTION The remnants of brushw
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When hcnlhic bivalves extend llien
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the burrow depths and on the fracti
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INTRODUCTION Ms,i invest 409 of (he
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able lo sw itch 10 oiher prey which
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Long-term, broadly-based research c
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Chapter 1 SEASONAL VARIATION IN BOD
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SEASONAL VARIATION IN BODY WEIGHT O
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Tahle 1 Weight loss ('•- ± SE) m
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i 60 50 40 30 20 10 0 • INFESTED
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240- SEASONAL VARIATION IN BODY WEI
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20 10 0 -10 -20h 2 3 4 5 6 7 8 9 se
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a E 400 - S. plana 35 mm 320 240 16
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Chapter 2 HOW THE FOOD SUPPLY HARVE
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FOOD SUPPLY HARVESTABLE BY WADERS H
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Methods The study sites were situat
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less than that of bivalves, partly
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I Fig. 3). Peak condition was reach
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total biomass since most of those t
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on the basis of the preceding and t
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However, for obvious reasons, we ma
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prey. A decrease in the prey densit
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Tahle 2. The intake rate ol < lyste
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* ' % -. . ; a X - . - * • ^ •
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(Zwarts & Wanink 1989). In quiet we
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general law relating handling time
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nearly twice as much time (0.79 s).
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4 5 6 7 8 9 size class of Corophium
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and annually. Second, the lower siz
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Prey switching Waders feeding on ti
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autumn and spring, and the contrary
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where they switch to surface-living
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Chapter 3 BURYING DEPTH OF THE BENT
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DEPTH AND SIPHON CROPPING IN SCROBI
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I DEPTH AND SIPHON CROPPING IN SCRO
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DEPTH AND SIPHON CROPPING IN SCROBI
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Table 3. Three-Way analysis Of vari
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Chapter 4 SIPHON SIZE AND BURYING D
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15 20 size (mm) Fig. 3. Cerasioderm
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10 size (mm) SIPHON SIZE AND DEPTH
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o, 7 01 5 | * CL 5- SIPHON SIZE AND
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4 Q) Si •a a. 16- 20- A predator:
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prey risk for an animal al a depth
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Table 6. Size al which there is a m
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* ' 1 /-/ "».-^*«C
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face and so expose themselves to a
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surface in die containers was varie
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50 OOF 310.00 I 5.00 ^ 1.00 3=" 0.5
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Tahle 1. Macoma and Scrobicularia.
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siphon would not have to reach the
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known siphon weight and burying dep
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ACCESSIBLE PREY ARE OFTEN IN POOR C
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1 2 3 4 burying depth (cm) Kin. I.
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I—1 • • : : : : ! - ! -|-r 0
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Chapter 7 DOES AN OPTIMALLY FORAGIN
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OPTIMAL FORAGING AND THE FUNCTIONAL
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100 200 300 prey density (n-m-2) Fi
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Table I. Results of five one way an
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Table 2. Results of eight iwo-wav a
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prey density II III Fig. 12. Freque
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PREY SIZE SELECTION AND INTAKE RATE
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Predicted 'passive size selection'
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lig. 2. Larger Mussels are less ava
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Fig. 5. Scrobicularia plana. Size c
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and maiiv are too thick-shelled to
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The measurements of handling time i
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1 2 3 4 5 6 7 probing depth (cm PRE
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valves may vary by a factor of two
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optimal foraging model, the minimum
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their gut is full? Do they reduce t
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PREY PROFITABILITY AND INTAKE RATE
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catchers to take only certain prey
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licult error of estimate arose if p
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Counts of feeding and non-feeding b
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20 30 40 50 shell length (mm) PREY
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Nereis Arenicola tipuia earthwo'm M
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take rate. We might therefore expec
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prey species, using parallel slopes
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5.0 4.0 1-3.0 a & • % * • * •
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time during the feeding period. As
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winter. Similarly, handling time in
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5.0 - f-4.0 S 3.0 in I 20 a 2 a | 1
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situation arrived in the western pa
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• ' • 14 PREY PROFITABILITY AND
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Notes lo appendix: PREY PROFITABILI
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Chapter 10 WHY OYSTERCATCHERS HAEMA
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2 4 6 8 10 time on feeding area (h)
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80- 60- o 80 60- 40- 20- INTAKE RAT
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est of bod\ behind: an estimated 22
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INTAKE RATE AND PROCESSING RATE IN
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Wanink 1993). The energy content of
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(7) Age All studies dealt with adul
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irds over long periods. As an examp
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Discussion There is no difference i
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comparison between the weight of ih
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. 1', L ! •
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Introduction PREDICTING SEASONAL AN
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PREDICTING SEASONAL AND ANNUAL FLUC
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1000 r 1 II" 1 - r^Jan'80 PREDICTIN
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IOO BO 60 40 20 0 PREDICTING SEASON
Page 254 and 255: PREDICTING SEASONAL AND ANNUAL FLUC
Page 265 and 266: WHY KNOT TAKE MEDIUM-SIZED MACOMA W
Page 267 and 268: in Zwarts & Esselink 1989). The len
Page 269 and 270: shell length (mm) FIR. 3. Peringia.
Page 271 and 272: fused, specimens larger than this w
Page 273 and 274: 50 100- s s I — f = S. plana, n=2
Page 275 and 276: area is twice as large as the touch
Page 277 and 278: 10 15 lower size threshold (mm) Fig
Page 279 and 280: lime (Hughes 1979). This would furt
Page 281 and 282: WHY KNOT TAKE MEDIUM-SIZED MACOMA T
Page 283 and 284: Chapter 13 ANNUAL AND SEASONAL VARI
Page 285 and 286: VARIATION IN FOOD SUPPLY OF KNOT AN
Page 287 and 288: Two sites (N and M in Fig. 2) were
Page 289 and 290: 20 30 VARIATION IN FOOD SUPPLY OF K
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Page 293 and 294: July ' Aug ' Sept Fig. 9. Proportio
Page 295 and 296: available. There must, however, be
Page 297 and 298: Chapter 14 SEASONAL TREND IN BURROW
Page 299 and 300: BURROWING AND FEEDING IN NEREIS SEA
Page 301 and 302: Table 2. Results of a 2-way analysi
Page 303: June 1981 June 1982 is * N.MUD •
Page 307 and 308: 6 - n=!080 5 • g 4 CP > i 3 CO CD
Page 309 and 310: 1985) and Curlew (/wails ,v, Lsseli
Page 311: Chapter 15 VERSATILITY OF MALE CURL
Page 314 and 315: Smid! 1951. Muus 1967, Wolff 1973,
Page 316 and 317: 0.6 0.8 1.0 1.2 1.4 1.6 jaw lengih
Page 318 and 319: Na oi both Nrieck Fig. 7. Numenius
Page 320 and 321: 6 8 10 12 14 16 18 worm length (cm)
Page 322 and 323: too (Fig. 11 A). Indeed, the averag
Page 324 and 325: VERSATILITY OF CURLEWS FEEDING ON N
Page 326 and 327: total time spent al the surface. Th
Page 328 and 329: 2 4 . • 2.2 • 30 .-.2.0 to Q. 1
Page 331 and 332: PREY DEPLETION BY OYSTERCATCHER AND
Page 333 and 334: the rule: the observed lower limit
Page 335 and 336: to locate the clams after they had
Page 337 and 338: Curlew, by bury ing some hundreds o
Page 339 and 340: PREY DEPLETION BY OYSTERCATCHER AND
Page 341 and 342: SAMENVATTING 345
Page 343 and 344: Voorgeschiedenis In 1960 verscheen
Page 345 and 346: maken. Als gebied A een grotere voe
Page 347 and 348: omdat ze nog vrijwel niets wegen. l
Page 349 and 350: kunnen opzuigen. of diep leven en z
Page 351 and 352: van de uitgerekte sifo over het wad
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doende nonnetjes van 10 tot 15 mm l
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aangevoerde voedsel en de wulp past
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zijn dan twee jaar en wulpen geen s
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was dan ook dank/ij de inzet van al
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REFERENCES 367
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Allen RL. 1983. Feeding behaviour o
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BreyT. 1989. Der Einfluss physikali
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latie tol chironoiiiiilen en de wai
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huch der Vogel Milteleuropas, Band
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llolmann II. & H. Huerschelmann 196
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l-cndrem D.W. 1984. Flocking, feedi
Page 377 and 378:
Pekkarinen M. 1984. Regeneration of
Page 379 and 380:
lion of Mussels Mytilus edulis hy O
Page 381 and 382:
lulal Dal esiuanes: a comparison of
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