. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PROTOGYNY IN GNORIMOSPHAEROMA OREGONENSE 103 an ethanol series (30%, 50%, 70%, 95%, and 100% ethanol in distilled water), critical-point dried in carbon dioxide (31°C, 1100 psi), sputter coated with gold for 10 min, and photographed using a Jeol JSM-35 scan- ning electron microscope. Results Field survey Examination of field aggregations. Gnorimosphaeroma oregonense was patchily distributed among the shell debris and barnacle- and mussel-covered rocks in Grappler Inlet. In September 1992, densities varied from 80 to 13,136 i
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PROTOGYNY IN GNORIMOSPHAEROMA OREGONENSE 103 an ethanol series (30%, 50%, 70%, 95%, and 100% ethanol in distilled water), critical-point dried in carbon dioxide (31°C, 1100 psi), sputter coated with gold for 10 min, and photographed using a Jeol JSM-35 scan- ning electron microscope. Results Field survey Examination of field aggregations. Gnorimosphaeroma oregonense was patchily distributed among the shell debris and barnacle- and mussel-covered rocks in Grappler Inlet. In September 1992, densities varied from 80 to 13,136 individuals per square meter. Because two of the ten sam- ples were extremely large (« = 642 and 821), eight samples were fully analyzed for population structure and the two large samples were subsampled by randomly mixing the isopods in 1 1 of water and removing a fraction of the volume from the agitated solution (Wrona et a!.. 1982). Of the 329 individuals examined, 78% were juveniles, 15% females (mature and receptive), and 7% males (Fig. 1). The operational sex ratio (mature males to receptive fe- males) was 1:1. Marked sexual dimorphism was evident among male and female G. oregonense (Fig. 1; Table II). Mean body length differed significantly among females and males (ANOVA; F = , P < ). Receptive females (RFP and RF) were significantly smaller than mature females, and mature females with penes (MFP) were not different in body length from mature females with- out penes (MF) (Table II). There was very little overlap in size range between mature females and mature males (Fig. 1). Penes were present on all males, on 30% of mature females (n = 80), and on 11% of receptive females (n = 38) sampled in September 1992. All mature females (n = 40) collected in November 1992 had small penes. No other differences in body morphology were evident. Penis length was related to sex and reproductive ma- turity. Mature females (n = 35) had penes that were sig- nificantly smal
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
