A Day in the Life of Fish Larvae: Modeling Foraging and Growth Using Quirks

Abstract

This article introduces “Quirks,” a generic, individual-based model synthesizing over 40 years of empirical and theoretical insights into the foraging behavior and growth physiology of marine fish larvae. In Quirks, different types of larvae are defined by a short list of their biological traits, and all foraging and growth processes (including the effects of key environmental factors) are modeled following one unified set of mechanistic rules. This approach facilitates ecologically meaningful comparisons between different species and environments. We applied Quirks to model young exogenously feeding larvae of four species: 5.5-mm European anchovy (Engraulis encrasicolus), 7-mm Atlantic cod (Gadus morhua), 13-mm Atlantic herring (Clupea harengus), and 7-mm European sprat (Sprattus sprattus). Modeled growth estimates explained the majority of variability among 53 published empirical growth estimates, and displayed very little bias: 0.65%±1.2% d−1 (mean ± standard error). Prey organisms of ∼67% the maximum ingestible prey length were optimal for all larval types, in terms of the expected ingestion per encounter. Nevertheless, the foraging rate integrated over all favorable prey sizes was highest when smaller organisms made up >95% of the prey biomass under the assumption of constant normalized size spectrum slopes. The overall effect of turbulence was consistently negative, because its detrimental influence on prey pursuit success exceeded its beneficial influence on prey encounter rate. Model sensitivity to endogenous traits and exogenous environmental factors was measured and is discussed in depth. Quirks is free software and open source code is provided.

Exploring the microzooplankton–ichthyoplankton link: a combined field and modeling study of Atlantic herring (Clupea harengus) in the Irish Sea

“…Various studies employing different methods have estimated that herring larvae need~2 µg C*L −1 of prey biomass to survive at temperatures close to those observed in the present study (Munk and Kiørboe, 1985;Figueiredo et al, 2005;Peck et al, 2012;Huebert and Peck 2014). The biomass of ciliates and dinoflagellates at some stations in our study would surpass this threshold but, at most stations and in both years, additional prey biomass from nauplii and copepodites would also be required to support observed (in situ) growth rates.…”

Modeling the effects of temperature on the survival and growth of North Sea cod (Gadus morhua) through the first year of life

“…This restriction was caused by several reasons. First, size-specific parameters of foraging models (e.g., handling time) are only well established for small larvae (Letcher et al, 1996;Huebert and Peck, 2014). In many cases, no laboratory data exist to extend these mechanistic functions to larger body sizes.…”

Development and application of the adverse outcome pathway framework for understanding and predicting chronic toxicity: II. A focus on growth impairment in fish

“…For example, body size affects vulnerability to predation (Law et al, 2009;Pettorelli et al, 2011), overwinter survival rates (Quinn and Peterson, 1996) and reproductive success (Jawad and Busneina, 2000;Rideout and Morgan, 2010). Growth-related metrics can be relatively easily incorporated into population models (Crowder et al, 1992;Weitz and Levin, 2006;Murphy et al, 2008;Baldwin et al, 2009;Huebert and Peck, 2014).…”