FISHERY BULLETIN; VOL. 86, NO. 2 



and prey abundance estimates standardized by 

 clump volume. Prey abundance data were ana- 

 lyzed using a two-way fixed-effects ANOVA on 

 log transformed data and Bonferroni pairwise 

 multiple comparisons. 



Habitat Selection/Settling Experiments 



We tested postlarval settlement and juvenile 

 habitat selection in laboratory experiments using 

 clumps of Laurencia spp. with high- and low-silt 

 loads (referred to hereafter as silted and un- 

 silted); the null hypothesis being equal selection 

 of both habitats. Experiments were conducted in 

 fourteen 75.7 L aquaria with subgravel filters 

 and circulating current of 3 cm s ^ Light was 

 provided by skylights and fluorescent lights with 

 a photoperiod of approximately 14L:10D. Two 20 

 cm diameter algal clumps, one silted and one un- 

 silted, were situated 25 cm apart at opposite ends 

 of each aquarium and at least 5 cm from aquar- 

 ium walls. The number of natural prey in both 

 silted and unsilted clumps far exceeded the num- 

 ber eaten daily by a juvenile. To further control 

 food availability in experiments with juveniles 

 we added equal amounts (10 mg) of Tetramin^ 

 fish food to each clump, providing an overabun- 

 dance of food available ad libitum. If juveniles 

 chose one type of algal clump over the other, then 

 their selection was most likely based on the pres- 

 ence or absence of silt, because food abundance 

 and quality were similar, if not strictly identical, 

 in both types of algal clumps. Pueruli neither feed 

 nor respond to the differential abundance of po- 

 tential prey (Herrnkind and Butler 1986). Silted 

 algae was collected from the No Name Key site 

 (see section on Algal Silt Content and Prey Con- 

 tent); unsilted algae was collected just offshore of 

 the Sea World Marine Science and Conservation 

 Center on Long Key. Fresh algal clumps were 

 used in each experimental replicate. An experi- 

 ment was initiated by introducing a single 

 puerulus or juvenile spiny lobster to the center of 

 an aquarium through a 5 cm diameter PVC pipe. 

 Once a spiny lobster settled to the substrate, the 

 pipe was slowly withdrawn allowing the lobster 

 to move freely about the aquarium. This tech- 

 nique prevented "tailflipping" by lobsters and fa- 

 cilitated active selection of habitats. Twenty-four 

 hours later we located the lobsters and recorded 

 their positions, as in previous experiments 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



(Herrnkind and Butler 1986). Fourteen spiny lob- 

 sters were tested on day 1, 14 more on day 2, and 

 so on until our stock of animals was depleted. 

 Each lobster was used only once. All pueruli were 

 collected on the incoming tide from the plankton 

 in interisland channels. Pueruli were either 

 tested immediately or allowed to metamorphose 

 for later use in experiments requiring juveniles. 

 Data were analyzed with log-linear Goodness-of- 

 fit tests. 



Metamorphosis Experiment 



The effect of siltation on the survival and time- 

 to-metamorphosis of pueruli was tested experi- 

 mentally in an outdoor, flow-through seawater 

 system. One freshly collected puerulus was placed 

 in each of 46 seawater-filled 1 L plastic beakers, 

 23 containing 5 cm diameter clumps of unsilted 

 algae and the other 23 an equal amount of silted 

 algae. Each container was independently sup- 

 plied with flowing, filtered seawater. Algal 

 clumps were replaced daily. Pueruli do not feed 

 and their habitat selection operates independent 

 of food availability (Herrnkind and Butler 1986), 

 thus no food was added to the containers. Sea- 

 water temperature in the beakers remained be- 

 tween 26° and 28°C; photoperiod was approxi- 

 mately 14L:10D. Pueruli were monitored daily 

 and their survival and time-to-metamorphosis 

 recorded. 



Pueruli were collected as transparent postlar- 

 vae from the plankton in interisland channels 

 which concentrate oceanic postlarvae as they 

 move into Florida Bay nursery areas. Time-to- 

 metamorphosis values represent the elapsed time 

 (in days) from puerulus collection until metamor- 

 phosis into the first benthic stage. Values are 

 likely to differ among collections as different co- 

 horts of pueruli arrive inshore. There are cur- 

 rently no techniques available to determine the 

 actual age of pueruli (i.e., time since metamor- 

 phosis from the phyllosoma stage), but estimates 

 of duration of the puerulus stage range from 

 2 weeks to 1 month (Lyons 1980; Calinski and 

 Lyons 1983). Differences in time-to- 

 metamorphosis between the two treatments were 

 analyzed via a two-sample ^-test. 



Juvenile Spiny Lobster Prey Selection 

 Experiments 



Laboratory experiments were conducted to de- 

 termine juvenile spiny lobster prey preference 



334 



