@article{ratchford_eggleston_2000, title={Temporal shift in the presence of a chemical cue contributes to a diel shift in sociality}, volume={59}, ISSN={["0003-3472"]}, DOI={10.1006/anbe.1999.1383}, abstractNote={Spatial and temporal variation in animal aggregations may be due to variation in the presence of cues for aggregation (or disaggregation) or to variation in the receptivity of the animal to a particular cue or suite of cues. Spiny lobsters, Panulirus argus, forage solitarily but are often found aggregated in their diurnal shelters. An important proximate cause of aggregation among spiny lobsters is a scent they produce that influences shelter choice by conspecifics. We examined how variability in the presence of, or response to, such a chemical cue may contribute to diel shifts in sociality among spiny lobsters. We conducted a series of Y-maze shelter choice experiments using lobsters that were either maintained under altered dark:light schedules in the experimental arena or under natural lighting in the head tanks. Lobsters that were maintained on a light schedule 8 h later than normal chose shelters at their dawn (corresponding to the middle of the night for lobsters in the head tanks); however, their choices of shelter were not influenced by scents of conspecifics. Lobsters that were maintained on a schedule 8 h earlier than normal chose shelters in the middle of their night (corresponding to dawn for the lobsters in the head tanks). Their choices of shelter were significantly influenced by conspecific scents. These results suggest that the chemical cues for aggregation, released by spiny lobsters, are present discontinuously, that spiny lobsters are influenced by conspecific odours continuously, and that aggregation is controlled by temporal variation in the presence of a chemical cue. Copyright 2000 The Association for the Study of Animal Behaviour.}, number={2000 Apr.}, journal={ANIMAL BEHAVIOUR}, author={Ratchford, SG and Eggleston, DB}, year={2000}, month={Apr}, pages={793–799} }
 @article{ratchford_1999, title={So how do spiny lobsters form groups?}, volume={12}, number={1}, journal={Lobster Newsletter}, author={Ratchford, S. G.}, year={1999}, pages={8–10} }
 @article{ratchford_eggleston_1998, title={Size- and scale-dependent chemical attraction contribute to an ontogenetic shift in sociality}, volume={56}, ISSN={["0003-3472"]}, DOI={10.1006/anbe.1998.0869}, abstractNote={Caribbean spiny lobsters, Panulirus argus, reside solitarily during the first months postsettlement, but shift to gregarious shelter use in later juvenile stages, at sizes as small as 15 mm in carapace length. To determine whether receptivity to or production of a chemical attractant among spiny lobster conspecifics is dependent upon body size or spatial scale, we conducted a series of overnight Y-maze shelter choice experiments. We placed a test lobster in an experimental arena and allowed it to choose between two shelters, which differed only in that water flowing by one shelter contained sea water that had passed through a header tank containing a conspecific. We varied the size of the lobster in the arena, the size and number of lobsters in the header tank, and the size of the experimental arena. Lobsters of all sizes tested released odours that attracted conspecifics; however, a single small lobster could attract other conspecifics only in the small arena. Lobsters greater than 15 mm in carapace length were attracted to shelters from which conspecific odours were emanating, while smaller lobsters were not. The results of this study suggest that: (1) the earliest benthic stages (less than 15 mm in carapace length) are unresponsive to conspecific odours, but lobsters greater than 15 mm in carapace length are attracted by conspecific odours; and (2) large lobsters produce a sufficient quantity of scent to attract conspecifics over distances of at least a few metres, whereas small lobsters (15-30 mm in carapace length) cannot. Body size- and spatial scale-dependent attraction could contribute to the shift from solitary to gregarious shelter use among Caribbean spiny lobsters. Copyright 1998 The Association for the Study of Animal Behaviour.}, number={4}, journal={ANIMAL BEHAVIOUR}, author={Ratchford, SG and Eggleston, DB}, year={1998}, month={Oct}, pages={1027–1034} }
 @article{eggleston_lipcius_marshall_ratchford_1998, title={Spatiotemporal variation in postlarval recruitment of the Caribbean spiny lobster in the central Bahamas: lunar and seasonal periodicity, spatial coherence, and wind forcing}, volume={174}, ISSN={["0171-8630"]}, DOI={10.3354/meps174033}, abstractNote={A large-scale recruitment study of the Caribbean spiny lobster Panulirus argus in the central Bahamas identified (1 ) strong spatial coherence in settlement to inshore nursery habitats, (2) temporal variability due in part to stochastic wind forcing, and (3) lunar and seasonal periodicity in settlement. First, we quantified lunar variation in settlement on standardized artificial substrates to determine whether or not intraand inter-annual variability In recruitment could be adequately described by measuring influx of postlarvae during the first quarter of each new moon, as suggested by previous studies. Next, we compared settlement data obtained from artificial surface substrates to concentrations of postlarvae In the water column and benthic settlement. Long-term (6 yr) spatiotemporal variation in postlarval settlement was then quantified at 8 sites spanning a longitudmal and onshore distance of 43 km and 11 km, respectively. Lastly, we examined the relationship between postlarval settlement and environmental variables with time-series analyses. The key findings were that: (1) signlficant lunar (first quarter of lunar phase) and seasonal (fall peak) periodicities in settlement were consistent across sites; (2) postlarval settlement varied more across sites (-600%) than between years at a single site (-50%), and inter-site differences were consistent across time (i.e. some sites always had higher settlement than others); (3) settlement was correlated with along-shore winds blowing towards the southeast, but not with cross-shelf winds or water temperature; (4) floating. 'Witham-type' artificial settlement 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 and benthic settlement may depend upon benth~c habitat availability and postlarval 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 recruitment over various scales of time and space.}, number={1998 Nov. 26}, journal={MARINE ECOLOGY PROGRESS SERIES}, author={Eggleston, DB and Lipcius, RN and Marshall, LS and Ratchford, SG}, year={1998}, pages={33–49} }