We quantified daily larval settlement of the acorn barnacle Semibalan~is balanoides in a small embayment within Narragansett Bay, Rhode Island, USA, to examine the hypothesis that local wind patterns influence shoreline settlement. Daily larval settlement and the accumulation of barnacle recruits were both strongly correlated with local wind patterns within and among years. When prevailing winds were out of the south, larval settlement was enhanced on the northern side of the bay, whereas when winds were out of the north, larval settlement was enhanced on the southern side of the bay. These patterns were observed over 2 settlement seasons and led to daily as well as interannual spatial patterns in both larval settlement and the accumulation of barnacle recruits. The patterns of shoreline settlement appear to be caused by wind-induced changes in larval concentrations on different sides of the bay. Water column larval densities were strongly correlated with daily wind patterns. Larval densities were always highest on the down-wind side of the bay. Our data show that spatial and temporal patterns in the settlement of benthic invertebrates can be strongly linked to local weather conditions through the transport of larvae by wind-dr~ven currents.

ABSTRACT. The abundance of neustonic postlarvae and newly recruited benthic lobsters Homarus americanus was measured for 2 yr along the central coast of Maine, USA. Postlarvae first appeared in significant numbers in late July, rapidly increased in early August to ca 10 to 20 (1000 m 2 ) ' (0.5 m depth)', then gradually declined throughout August and into early September. Late intermolt stages Dl to Ds characterized most of the neustonic population, with a shift in dommance to D3 in the wanner year (1990). Postlarval abundances differed little between years: the seasonally and spatially averaged daily abundances were 5.58 (1000 m2)-' (0.5 m)"' Â 0.77 (SE) and 6.76 Â 1.92 in 1989 and 1990, respectively. In contrast, there was a statistically significant difference in benthic recruitment measured in September. New recruits, lobsters with carapace length 5 10 mm, averaged 1.66 md. m 2 Â 0.37 (SE) in 1989 and 0.79 Â 0.22 in 1990. Spatial patterns in recruitment density at the sampling sites were positively correlated among years (r2 = 0.82) and did not appear to be related to distribution patterns of postlarvae. It seems likely that habitat type substantially influenced benthic recruitment patterns. Moreover, local differences in recruitment density of the first cohort were conserved over the 2 seasons of observation, supporting earlier assertions that new recruits are relatively sedentary. We develop a simple diagnostic model of the pelagic-to-benthic transition in lobster recruitment that accounts for the increase in density by 2 orders of magnitude from postlarval to benthic (recruit) stage, and we use this model to suggest plausible rates of postlarval diving and settlement that describe average and sitespecific recruitment in the 2 years.

Lipofuscln content was determined in the brains of 41 American lobsters Homarus amencanus (Milne-Edwards) aged 4, 13 and 27 mo reared individually at 19 to 20°C. Llpofuscin was quantified by fluorescence microscopy and image analysis. Lipofuscin granules occurred In each age group and in the oldest group appeared as large aggregations collectively averaging 2.1 % of the area of histological sections of the olfactory lobe cell mass. Carapace length-corrected lipofuscin area % gave the highest correlation with age (r = 0.99, p < 0 0001) and a non-linear best fit regression ( y = 0.00264 X ~g e~'~) .The size and number of l~pofuscln granules and carapace length were also significantly related to age. Lipofuscln concentrat~on was not significantly correlated with carapace length wthin any of the 3 age classes (4 mo: r = -0.078, 13 mo: r = -0.20, 27 mo. r = -0.351). These results suggest the possibility that the lipofuscin technique can differentiate cohorts In natural populations. However, environmental temperature and the possibility of other factors affecting metabolic rate may need to be taken into account when attempting to apply the laboratory model to wild populations.