Diel vertical migration related to foraging success in snapper Chrysophrys auratus larvae

Abstract

The vertical distributions of marine fish larvae can change markedly over time due to changes in diel vertical migration (DVM). DVM is thought to be influenced by a number of factors including light levels and prey availability. In Port Phillip Bay, Australia, the DVM of snapper Chrysophrys auratus (Sparidae) larvae and their prey were investigated using depth-stratified sampling (four depths: surface, 4, 8, 11 m) over 4 sampling periods of 24 h. We sampled ichthyoplankton at the same location twice in 2 spawning seasons (austral summers of 2008/09 and 2009/10). Sufficient snapper larvae for analysis of DVM behaviour occurred once in each season. At both 24 h sampling times, snapper larvae displayed the same DVM behaviour of nocturnal diffusion and diurnal aggregation at ~4 m depth. The water column was homogenous for temperature, salinity, dissolved oxygen and fluorescence during the two 24 h periods. Two out of 6 important zooplankton prey of snapper larvae were also aggregated at ~4 m depth during the day. Gut analyses indicated that larvae only fed during daylight hours and had an average digestion time of 3 to 5 h. Snapper larvae had highest foraging success at 4 m depth, which was supported by minimal digestion of prey at time of capture. This suggests that the observed DVM was related to feeding success, and that 4 m depth provided optimal foraging conditions. These results have important implications for developing individual-based biophysical models of larval transport that include interaction with prey fields and larval foraging success. 433: 185-194, 2011 the day (e.g. Brewer & Kleppel 1986, Davis et al. 1990, Jenkins et al. 1998. Diel vertical migratory behaviour can vary taxonomically, with nocturnal ascent being the most commonly observed pattern for marine fish larvae (Neilson & Perry 1990). Vertical behaviour can also vary ontogenetically, with older larvae commonly demonstrating a more pronounced DVM pattern compared to smaller, less developed pre-flexion stages (Neilson & Perry 1990). KEY WORDS: Light levels · Marine fish larvae · Food availability Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerMarine fish larvae may vertically migrate in response to a variety of factors, including to avoid predators (Yamashita et al. 1985), to optimise feeding success (Fortier & Leggett 1983, Munk et al. 1989, and to influence larval dispersal (reviewed by Leis 2006). In marine temperate fish larvae, patterns of DVM behaviour have more often been interpreted as responses to prey-predator interactions than to abiotic factors (Neilson & Perry 1990, Sabates 2004. Although a relationship between prey density and larval DVM behaviour has been found for numerous taxa, for example herring Clupea harengus (Munk et al. 1989), sandeel Ammodytes marinus (Jensen et al. 2003) and mackerel Scomber scombrus (De La Fontaine & Gascon 1989), other studies have found no such relationship (e.g. Brewer & Kleppel 1986, Jenkins et al. 1998. However, the relationship betwee...

Biophysical modelling of snapper Pagrus auratus larval dispersal from a temperate MPA

“…No in situ data are available on snapper vertical be haviour in New Zealand, thus the data for the other 2 behavioural modes were derived from P. auratus in Australia (Murphy et al 2011) and the closely related red seabream P. major (Kinoshita & Tanaka 1990). The behaviours in these studies differed markedly.…”

“…Briefly, in the Australian study, snapper larvae exhibited nocturnal diffusion and aggregation at a specific depth stratum (4 m) during the day (Murphy et al 2011 Table 1. Behavioural and biological data used in the model in the present study, based on data from snapper (Pagrus auratus) populations in New Zealand (Pankhurst et al 1991) and Australia (Murphy et al 2011), and the sister species (P. major) in Japan (Kinoshita & Tanaka 1990). Note: position in water column for P. major eggs assumed to be the same as for P. auratus.…”

“…Recently, the importance of incorporating biological and behavioural data into larval connectivity studies has also been recognised, as speciesspecific differences in the swimming behaviour, directionality and sensory capabilities have been documented (Clark et al 2005, Leis et al 2006, Montgomery et al 2006, Leis 2007, Radford et al 2012. The swimming capabilities of fish larvae have also been shown to be more than capable of influencing their dispersal trajectories in response to changing prey and environmental conditions (Clark et al 2005, Leis et al 2006, 2007b, Murphy et al 2011. The importance of larval behaviour in mediating dispersal trajectories is also supported by a suite of recent genetic larval connectivity studies, mostly on coral reef species, showing surprisingly high levels of selfrecruitment and/or small-scale (10s to 100s of km) larval retention and recruitment to their natal habitat (Jones et al 2005, Carreras-Carbonell et al 2007, Planes et al 2009, Christie et al 2010, Saenz-Agudelo et al 2011, Harrison et al 2012, D'Aloia et al 2013.…”

Estimating activity-specific energy expenditure in a teleost fish, using accelerometer loggers

“…Trade-offs between the cost and benefit of specific behaviours govern the success and survival of animals through natural selection. For example, for many species of fish the choice of being active or inactive at different times of the day will affect both feeding success (Bestley et al 2008, Murphy et al 2011) and the risk of predation (Stuart-Smith et al 2007, Béguer-Pon et al 2012. Measuring the energy turnover and ways in which energy is allocated to specific activities is therefore of central importance in our understanding of behavioural and physiological ecology.…”

Recent advances in telemetry for estimating the energy metabolism of wild fishes

“…For many species of fishes, the choice between being active or inactive at different times of the day will affect both feeding success (Bestley et al ., ; Murphy et al ., ) and the risk of predation (Stuart‐Smith et al ., ; Béguer‐Pon et al ., ). Measuring energy turnover, and the ways in which energy is allocated to specific activities, is therefore of central importance to understanding behavioural and physiological ecologies.…”