Temperature dependent larval duration and survival of the western king prawn, Penaeus (Melicertus) latisulcatus Kishinouye, from Spencer Gulf, South Australia

The effects of temperature on growth, development and survival of penaeid prawn larvae ultimately influence recruitment to fisheries. This is of particular importance for temperate prawn fisheries in South Australia that target the semi-tropical western king prawn Penaeus (Melicertus) latisulcatus. P. latisulcatus resides at its lower temperature limit in South Australia, where it is restricted to the warmer waters of the gulf and embayment systems. Duration and survival were determined for three larval stages of P. latisulcatus reared at constant temperatures: 17, 20, 22.5 and 25°C. Data were subsequently used to construct a larval development model to generate predictions of larval duration for varying hatch dates when water temperature was within spawning range (November–May) at two different spawning grounds within Spencer Gulf (north vs. south). Results demonstrated that water temperature had affected larval development, duration and subsequently total survival. A power relationship was found between temperature and larval duration such that lower temperatures exerted the greatest influence. Under a constant laboratory temperature regime, total larval development ranged from 12.7days (at 24.4°C) to 31.3days (at 17.1°C). Stage-specific duration was generally greatest for protozoea, while developmental variability among individuals was greatest at later stages and at higher temperatures. Daily survival (~98% day−1) was similar between 17°C (total end survival: 36%) and 25°C (total end survival: 74%) treatments, suggesting the upper thermal tolerance limit is greater than mean water temperature maxima in temperate Spencer Gulf. A seasonal larval duration model predicted total duration to be shorter at the beginning of the spawning season (26.8days: 9 November) due to increasing daily water temperatures, compared to later in the season (35.4days: 29 May). Furthermore, larval duration was predicted to be significantly shorter in warmer northern (minimum 12.7days) compared to southern (minimum 17.2days) spawning grounds. These results improve the understanding of the factors that affect larval dispersal, settlement and recruitment of P. latisulcatus. ► Larval development and duration of P. latisulcatus was dependent on temperature. ► Predicted duration was shorter early in the spawning season and in north Spencer Gulf. ► Survival rate was similar for 17°C and 25°C, total survival was greater for 25°C. ► Thermal tolerance range supportive of a semi-tropical