Spatiotemporal variation in postlarval recruitment of the Caribbean spiny lobster in the central Bahamas: lunar and seasonal periodicity, spatial coherence, and wind forcing

A large-scale recruitment study of the Caribbean spiny lobster Panulirus ar gus in the central Bahamas identified (1) strong spatial coherence in settl ement to inshore nursery habitats, (2) temporal variability due in part to stochastic wind forcing, and (3) lunar and seasonal periodicity in settleme nt. First, we quantified lunar variation in settlement on standardized arti ficial substrates to determine whether or not intra- and inter-annual varia bility in recruitment could be adequately described by measuring influx of postlarvae during the first quarter of each new moon, as suggested by previ ous studies. Next, we compared settlement data obtained from artificial sur face substrates to concentrations of postlarvae in the water column and ben thic settlement. Long-term (6 yr) spatiotemporal variation in postlarval se ttlement was then quantified at 8 sites spanning a longitudinal and onshore distance of 43 km and 11 km, respectively. Lastly, we examined the relatio nship between postlarval settlement and environmental variables with time-s eries analyses. The key findings were that: (1) significant lunar (first qu arter of lunar phase) and seasonal (fall peak) periodicities in settlement were consistent across sites; (2) postlarval settlement varied more across sites (similar to 600 %) than between years at a single site (similar to 50 %), and inter-site differences were consistent across time (i.e, some sites always had higher settlement than others); (3) settlement was correlated w ith along-shore winds blowing towards the southeast, but not with cross-she lf winds or water temperature; (4) floating, 'Witham-type' artificial settl ement substrates yielded an accurate index of postlarval concentration and flux past a given point: and (5) floating substrates were a relatively poor indicator of benthic settlement, though the relationship between surface a nd benthic settlement may depend upon benthic habitat availability and post larval supply. These results indicate that artificial settlement substrates provide a reliable index of postlarval supply to inshore nursery habitats, and that a combination of stochastic and deterministic forces influence re cruitment over various scales of time and space.