Weekly settlement of red and purple sea urchins (Strongylocentrotus franciscanus and S. purpuratus) was documented at sites in northern and southern California (USA) for 4 settlement seasons from 1990 to 1993. Newly settled sea urchins (<0.5 mm) were collected from standardized settlement surfaces (scrub brushes), identified and counted. There was marked seasonality in settlement. For both species, most settlement occurred during one to several episodes between February and July of each year. Settlement tended to be more regularly annual in southern than in northern California and settlement densities generally were higher in the south. This pattern is consistent with greater retention of water in the Southern California Bight and more energetic offshore advection of water in northern California S. purpuratus showed geographic coherence in settlement whereas S. franciscanus did not. For purple sea urchns, northern sites formed a group, a second group was formed by sites near Santa Barbara plus a site in Orange County, and a third group was formed by 3 sites at San Diego.

It has often been observed that the abundance of sea urchins is lower inside kelp forests and along their nearshore edges than outside their offshore boundaries. We tested the hypothesis that this distributional pattern is a reflection of settlement patterns by monitoring settlement on artificial surfaces at 3 kelp forests near San Diego, California. USA. We estimated settlement at paired sites under the canopy and outside the offshore edge of the kelp forests and at paired sites located 20 m outside the canopy near the inshore and offshore boundaries of each kelp forest. There was no evidence of an effect of dense stands of giant kelp on the settlement of purple sea urchins. The results for red sea urchins were ambiguous; in 3 of 7 comparisons, average settlement was h~g h e r or observations of higher settlement were more frequent offshore from the kelp forest than elsewhere. Although this could result from different effects on the 2 species, we think ~t probably was due to accidents of sampling We conclude that the distributional patterns of purple and red sea urchins relative to kelp forests are unllkely to reflect larval availability or settlement, but are more probably a function of post-settlement events We qualify our concl.usions because of the tremendous temporal variability in the physical and biological factors that can, potentially affect the local distnbution of sea urchin larvae. The 2 years of this study may be short relative to natural cycles.

A new theory IS proposed to explain the origln of some growth lines in echinoid splnes. It is proposed that lines form as part of a growth event initiated when a usually nongrowing spine no longer fits the growing tubercle on which it sits. Growth lines also can form in response to damage but neither cause of growth lines is periodic and hence lines cannot be used to determine age.

Pesticides must be applied to the target area uniformly. Uniformity of sprayer output is typically described by the coefficient of variation (CV) of the spray emitted. However, deposit size, number, and concentration interactions are overlooked when using this statistic. A measurement technique and alternative statistics, capable of documenting and separating qualitatively different spray patterns produced by quantitatively similar spray distributions were evaluated. Water and Roundup® Ultra with and without Kinetic™ and AgRhô™ DR 2000 were applied to plastic tape at 93.5 L/ha through XR8O03VS, TT11003VP, and TDVC-03/06 tips. Nigrosin was used as a tracer. Deposits were allowed to dry and were photographed at 2 cm intervals across the swath using an image analysis system. Deposit structure (#/cm2, size distribution and applied volume) was analyzed for each subsample. The data showed that while differences could be shown to occur in individual parameters, better separation of treatments was achieved with the use of the diversity statistics.