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Titolo:
Small-scale patterns in distribution and feeding of Atlantic mackerel (Scomber scombrus L.) larvae in the Celtic Sea with special regard to intra-cohort cannibalism
Autore:
Hillgruber, N; Kloppmann, M;
Indirizzi:
Biol Anstalt Helgoland, Stiftung Alfred Wegener Inst Polar & Meeresforsch,D-22607 Hamburg, Germany Biol Anstalt Helgoland Hamburg Germany D-22607 ,D-22607 Hamburg, Germany
Titolo Testata:
HELGOLAND MARINE RESEARCH
fascicolo: 2, volume: 55, anno: 2001,
pagine: 135 - 149
SICI:
1438-387X(2001)55:2<135:SPIDAF>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
DIEL VERTICAL MIGRATION; EARLY LIFE-HISTORY; THERAGRA-CHALCOGRAMMA; MARINE FISH; GOBIUSCULUS-FLAVESCENS; REACTION DISTANCE; BRITISH-ISLES; RATES; SELECTIVITY; ZOOPLANKTON;
Keywords:
mackerel larvae; vertical distribution; diet; diel patterns; cannibalism;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
71
Recensione:
Indirizzi per estratti:
Indirizzo: Hillgruber, N Biol Anstalt Helgoland, Stiftung Alfred Wegener Inst Polar &Meeresforsch,Notkestr 31, D-22607 Hamburg, Germany Biol Anstalt Helgoland Notkestr 31 Hamburg Germany D-22607
Citazione:
N. Hillgruber e M. Kloppmann, "Small-scale patterns in distribution and feeding of Atlantic mackerel (Scomber scombrus L.) larvae in the Celtic Sea with special regard to intra-cohort cannibalism", HELG MAR R, 55(2), 2001, pp. 135-149

Abstract

Short-term variability in vertical distribution and feeding of Atlantic mackerel (Scomber scombrus L.) larvae was investigated while tracking a larval patch over a 48-h period. The patch was repeatedly sampled and a total of12,462 mackerel larvae were caught within the upper 100 in of the water column. Physical parameters were monitored at the same time. Larval length distribution showed a mode in the 3.0 mm standard length (SL) class (mean abundance of 3.0 min larvae (x) over bar =75.34 per 100 m(3), s=34.37). Highest densities occurred at 20-40 in depth. Larvae <5.0 mm SL were highly aggregated above the thermocline, while larvae <greater than or equal to>5.0 mm SL were more dispersed and tended to migrate below the thermocline. Gut contents of 1,177 mackerel larvae (2.9-9.7 mm SL) were analyzed. Feeding incidence, mean number (numerical intensity) and mean dry weight (weight-based intensity) of prey items per larval out were significantly dependent on larval size. However, while weight-based feeding intensities continued to increase with larval length, numerical intensity peaked at 4-4.9 mm SL, indicating a shift in the larval diet. While first-feeding larvae relied most heavily on copepod nauplii and eggs, larvae greater than or equal to5.0 min SL initiated piscivorous feeding. All identifiable fish larvae were Atlantic mackerel. Thus, the piscivory was cannibalism. Larval feeding incidence and numerical feeding intensities peaked during daytime and were reduced at night. Daily ration estimates for first-feeding mackerel larvae <4.0 mm SL wereextremely low <(x)over bar> =1.43% body dry weight, but increased dramatically at 5.0 mm SL, i.e., at the onset of cannibalism, reaching >50% body dry weight in larva greater than or equal to8.0 mm SL.

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Documento generato il 10/07/20 alle ore 09:47:48