Effect of turbulence on feeding of larval
fishes: a sensitivity analysis using an individual-based model
B.A. Megrey, S. Hinckley-2001
ICES Journal of Marine Science, 58(5):
1015-1029
Abstract:
Recent research has shown that turbulence
can be important in the feeding of larval fishes. The interplay
of turbulence with other important factors affecting
larval feeding and growth rates is less known because
of the difficult problems associated with multi-factor
in situ experiments. We use an individual-based
model (IBM) of the early life stages of walleye pollock
(Theragra chalcogramma) to examine the sensitivity
of growth and mortality to turbulence. This probabilistic
and mechanistic model follows individual fish
through the egg, yolk-sac larvae, feeding larvae, and
juvenile stages, and includes development, behaviour,
feeding, bioenergetics, and growth for each life stage.
Biological processes are driven by physical factors
(temperature, salinity, and turbulence) derived from
a companion hydrodynamic model and configured for
environmental conditions prevalent in 1987. A foraging
submodel explicitly incorporates the effect of turbulence,
prey density, and larval size. Monte Carlo simulations
using Latin Hypercube Sampling methods were used to
perform a sensitivity analysis. The error analysis
examines the relative importance of various feeding-related
factors on larval growth and mortality. Model results
conform to wind-induced turbulence/contact-encounter rate
theory with maximum consumption rates occurring at
windspeeds of 7.2m s-1. Reactive distance, minimum
pursuit time, and weight-length conversion parameters
were the most important input parameters affecting the
turbulence-consumption processes. The rank order of
important input parameters shows that the
weight-length conversion power coefficient and
reactive distance (directly through the reactive distance-length
proportionality coefficient) were two factors that
influenced the largest number (17 out of 24) and
largest percentage (71%) of output variables. Feeding
depth was ranked third, influencing 50% of the output
variables. Our results show that smaller and younger
larvae are more sensitive to turbulent effects than
are larger and older larvae.
(National Oceanic and Atmospheric Administration,
National Marine Fisheries Service, Alaska Fisheries Science Center, 7600
Sand Point Way NE, Seattle, WA, 98115, USA, Tel: +1 206 526 4147, Fax: +1
206 526 6723, e-mail: bern.megrey@noaa.gov)