. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OBS OS BS1 S1 CC SWC1. BS2 SWC2 Source of chemical factor Figure 2A, B. Mean (±SEM) settlement rates of oyster larvae. The ranked order of settlement in response to solutions is: OBS > OS = BS1 = BS2 > SI = S2 = SWC1 = SWC2 (Student-Newman-Keuls multiple range comparison: F = : = 8. 63: P P > ). Conse- quently, the data indicate that the settlement inducers in each solution (OBS, OS, and BS1) have molecular weights between 500 and 1000 daltons. Discussion Ever since Cole and Knight-Jones (1939)
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OBS OS BS1 S1 CC SWC1. BS2 SWC2 Source of chemical factor Figure 2A, B. Mean (±SEM) settlement rates of oyster larvae. The ranked order of settlement in response to solutions is: OBS > OS = BS1 = BS2 > SI = S2 = SWC1 = SWC2 (Student-Newman-Keuls multiple range comparison: F = : = 8. 63: P P > ). Conse- quently, the data indicate that the settlement inducers in each solution (OBS, OS, and BS1) have molecular weights between 500 and 1000 daltons. Discussion Ever since Cole and Knight-Jones (1939) first described the gregarious nature of larval settlement in oysters, there has been debate about the sources of chemical inducers. Two schools of thought have emerged: one reports juvenile and adult oysters to be the source of inducers, whereas the other finds the source in biofilms (references in Intro- duction). Our results suggest that these contrasting view- points have resulted largely from differences in experi- mental approach. In this study we have separated both proposed sources of settlement inducers by preparing and testing solutions that contain compounds released either by oyster or by their external biofilms. We report here that holh sources produce waterborne substances rapidly provoking larval settlement. The small size of oyster larvae (250-350 ^m), and their sensitivity to handling, made them difficult subjects for T n SWC1 • - -• OBS „ - -• OT^- 3 A--- A OS T ^ * * •» BS1 * || 2 v — v NH4CI / r/ T^..I-T---I frt , •••'A * i * i * '1 . E 1 ,. J. ' T .' /' T o ° T / , T v T ~*7 ^ i 1 M 0 D|/4 I 1 1 v l 1 Ammonium Figure 3. Dose-responses of oyster larvae to serial dilutions of OBS, OS, BS1, and ammonium chloride (NH4CI) solutions, relative to seawater control (SWCI). Responses are expressed as mean (+SEM) settlement rates; dosages are expressed in ammonium concentrations. Abbreviations: oyster (O). biofilm (B). and shell
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
