Scope and consequences of variation in the early life history traits of a Caribbean coral reef fish
Successful settlement of reef fishes is more than successful larval transport between spawning sites and juvenile habitat. We have been actively involved in quantifying aspects of larval growth and survivorship for several model reef fishes. The analysis of fish otoliths is a central tool in this research as a method for comparing relative growth rates and condition among individuals (Sponaugle 2009, 2010). Building upon previous work on the relationship between variation in early life history traits and survival of fishes in Barbados (Searcy & Sponaugle 2000, 2001), and the effect of distinct physical oceanographic features on larval growth and transport (Sponaugle & Pinkard 2004a,b), we have been investigating natural variability in early life history traits and the consequences of that variability to recruitment (Sponaugle et al. 2006), early juvenile growth, and survival of a common reef fish, Thalassoma bifasciatum, in the Florida Keys (Sponaugle et al. 2006, Sponaugle & Grorud-Colvert 2006).
Kirszten Grorud-Colvert’s dissertation research showed how the strength and direction of selective mortality on this species varies seasonally (Grorud-Colvert & Sponaugle 2011) and she used experimental studies to tease apart critical ecological processes occurring during the transition between the larval and juvenile stage (Grorud-Colvert & Sponaugle 2006). This research was further extended to compare reef fish settlement to reserves and non-reserve areas (Grorud-Colvert & Sponaugle 2009). Michelle Paddack examined recruitment of parrotfishes (Paddack & Sponaugle 2008), and their effect on macroalgae (Paddack et al. 2006), as well as variation in the demography of older life stages across Florida Keys reefs (Paddack et al. 2009). Tauna Rankin used a long-term recruitment record, light trap collections, field manipulations, and otolith and molecular analyses to examine aspects of population replenishment in another model species, the bicolor damselfish, Stegastes partitus (Rankin & Sponaugle 2011, 2014).
Our time-series collections of larval arrival along the Florida Keys have shown that (1) near-reef larval fish assemblages differ markedly from offshore assemblages and their abundance is strongly event-related (Sponaugle et al. 2003), (2) very large multi-taxa pulses of settlement stage fish occur in association with the nearshore passage of mesoscale Florida Current eddies, and (3) such mesoscale eddies can also flush larvae out of the system (Sponaugle et al. 2005a, D'Alessandro et al. 2007). In a broader spatial context, our time series collections have also demonstrated that (4) larval supply to the lower Florida Keys greatly exceeds that to the upper Florida Keys (Sponaugle et al. 2012a).
PI on the project was Su Sponaugle. Additional support for this work was provided by EPA funding to the National Center for Caribbean Coral Reef Research, as well as data collected in conjunction with other funded projects.