Among amphidromous species, life-history traits of pelagic larvae show high variability between and within species and populations, due to the spatial and temporal variability of the marine environment. Temperature, food availability and seasonal conditions affect survival and larval growth. Among species with an extensive reproduction period, the pelagic conditions encountered by larvae vary according to the hatching date and induce variability in the postlarval and recruitment traits. Post-larvae of the amphidromous goby Cotylopus acutipinnis were collected every new moon between February 2008 and December 2009 at the mouth of a river on Reunion (Mascarene Archipelago, SW Indian Ocean). The relationship between pelagic larval duration (PLD), growth and marine temperature conditions was analysed using the chronological properties of otoliths. C. acutipinnis PLD (mean ± CI: 108.2 ± 1.2 d; range: 66 to 164 d) and size-atrecruitment (mean ± CI: 20.5 ± 0.1 mm; range: 17 to 23 mm) varied widely depending on the time of year. Back-calculation of hatching dates showed an extensive spawning season between November and July, which included 2 spawning peaks during the early austral summer and early winter. Summer spawning and high seawater temperature induced faster growth, shorter PLDs and smaller size-at-recruitment compared to early winter reproduction. The significant morphological changes that were demonstrated among amphidromous recruits might influence postrecruitment survival and juvenile settlement in freshwater. Selective mortality may occur according to early life-history traits such as growth patterns, size-at-recruitment and post-larval condition, and should be considered in population management.KEY WORDS: Cotylopus acutipinnis · Amphidromy · Otolith microstructure · Hatching date · Pelagic larval duration · Growth · Seasonal conditions · Sea surface temperature
Resale or republication not permitted without written consent of the publisherAquat Biol 15: [225][226][227][228][229][230][231][232][233][234][235][236] 2012 The pelagic phase plays a fundamental role for amphidromous populations, as it allows larval dispersion and gene flow between fragmented freshwater settlement sites , Keith et al. 2005. Otolithometry (and, to a lesser extent, sclerochronology) is often used to characterise early life history traits of pelagic larvae (Sponaugle 2010). Among marine fishes, the influence of pelagic conditions on growth and size-at-recruitment has been demonstrated in both temperate (Raventos & Macpherson 2005, Fontes et al. 2011) and tropical waters (McCormick & Molony 1995, Searcy & Sponaugle 2000, Bergenius et al. 2005. Among amphidromous species, on the other hand, patterns of marine growth are less known (Shen & Tzeng 2008, Lord et al. 2010. Their pelagic larval duration (PLD) is longer than that of most marine demersal species (Brothers et al. 1983, Radtke et al. 2001, Hoareau et al. 2007, Lord et al. 2010, and a significant PLD and size-at-recruitment variability has been observed between and w...