Linking behavioural ecology and oceanography: larval behaviour determines growth, mortality and dispersal

Abstract

Highly resolved general circulation models (GCMs) now generate realistic flow fields, and have revealed how sensitive larval drift routes are to vertical positioning in the water column. Sensible representation of behavioural processes then becomes essential to generate reliable patterns of environmental exposure (growth and survival), larval drift trajectories and dispersal. Existing individual-based models involving larval fish allow individuals to vary only in their attributes such as spatial coordinates, and not in their inherited behavioural strategies or phenotypes. We illustrate the interaction between short-term behaviour and longer-term dispersal consequences applying a model of larval cod Gadus morhua drifting in a GCM, and show how variations in swimming behaviour influence growth and dispersal. We recommend a deep integration of oceanography and behavioural ecology. First, we need to understand the causes and survival value of behaviours of larval fish, framed in terms of behavioural ecology. Second, we need practices to address how drift and dispersal of offspring are generating spawning strategies (timing and location) of adults, using life history theory. Third, the relative importance of local growth and mortality versus the need to drift to particular areas depend strongly on the mobility of organisms at the time of settling, or the spatial fitnesslandscape. The field of 'individual-based ecology' provides sound methods to approach this interface between evolutionary theory and physical oceanography.

Movement patterns and rheoreaction of larvae of a fluvial specialist (nase, Chondrostoma nasus): the role of active versus passive components of behaviour in dispersal

“…It has been shown that fish can detect fine-scale stimuli induced by the current and actively react to them from early larval stages onwards (Garner 1999;Stoll and Beeck 2012). In marine fish ecology, the importance of larval behaviour for dispersal has been recognized during the past decade (Fiksen et al 2007;Gallego et al 2007;Leis 2007), and the need to break "the behavioural black box" has been realized (Pineda et al 2007). Moreover, basic behavioural features of fish larvae have already been successfully incorporated into elaborate 3D models of physical-biological interactions, which have increasingly become an integral tool for understanding larval fish dynamics in the sea (Gallego et al 2007), while in rivers these methods are in their infancy (Schludermann et al 2012;Lechner et al 2016).…”

Survival probability of larval sprat in response to decadal changes in diel vertical migration behavior and prey abundance in the Baltic Sea

“…Fiksen et al (2007) stated that larval fish simply execute genetically preprogrammed responses to internal states or external stimuli. From our analysis, it could not be ultimately clarified whether the observed higher survival probability of larval sprat during the past decade was due to a change in behavior.…”

“…Wieland and Zuzarte (1991) found a deep maximum of small larvae (, 6 mm) occurring at 70-75 m and older larvae (up to 19 mm) predominantly in the upper 45 m. These differences in the vertical distribution of larvae with ontogeny suggest that most larvae hatch at deeper layers and then migrate to the upper layers, where they remain until at least the juvenile phase (Voss et al 2007). Besides ontogenetic changes in depth preference, vertical positions chosen by larval fish may be due to behavioral response to environmental gradients (Vikebø et al 2007). Strong selection pressures on habitat selection in larval sprat could be expected since the pelagic environment in the Baltic Sea is characterized by strong vertical gradients of abiotic as well as biotic variables that affect the growth of sprat larvae (i.e., temperature, prey concentrations, and the probability of being advected into unfavorable areas for Fig.…”

“…Depth-dependent dispersion and survival of Baltic sprat early life stages-Because of differences in vertical distribution, marine larval fish dwelling in layered current systems might be advected in different directions at different speeds (Vikebø et al 2007). For example, ocean circulation models suggest that passively drifting young larvae released at depths only 10 m apart may metamorphose into juveniles many weeks later at very different locations (Vikebø et al 2005).…”

“…From a fitness perspective, larval fish should avoid habitats (e.g., water depths) that increase the probability of encounters with predators. Vikebø et al (2007) modeled larval depth selection based on an inherent trade-off rule between growth (prey abundance) and mortality (predator contact). In most marine systems, the main potential predators of larval fish are planktivorous fish (Bailey and Houde 1989).…”