. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. D_ TIME (min) Figure 4. Percentages of Ciuwnlmi xixax larvae exhibiting settle- ment behavior as a function of length of the duration of their exposure to NH, or L-DOPA in the presence of Sulpiride. Sulpiride is a dopa- minergic receptor antagonist. (A) Effect of sulpiride on the ability of L- DOPA to induce settlement behavior. (B) Effect of sulpiride on the ability of NH, to induce settlement behavior. Larvae were pre-incubated in sulpiride (100 ) or seawater for 12 min. then L-DOPA (100 n\I). NH4C1 (10 ). sulpinde
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. D_ TIME (min) Figure 4. Percentages of Ciuwnlmi xixax larvae exhibiting settle- ment behavior as a function of length of the duration of their exposure to NH, or L-DOPA in the presence of Sulpiride. Sulpiride is a dopa- minergic receptor antagonist. (A) Effect of sulpiride on the ability of L- DOPA to induce settlement behavior. (B) Effect of sulpiride on the ability of NH, to induce settlement behavior. Larvae were pre-incubated in sulpiride (100 ) or seawater for 12 min. then L-DOPA (100 n\I). NH4C1 (10 ). sulpinde (100 nAI) or seawater were added as indicated by the arrows. Data are means ± standard error of triplicates followed through time. For each time point, treatments with the same letter, or no letter are not significantly different from each other. Only statistics for relevant time points are shown for clarity. Ammonia, as a by-product of protein catabolism, is excreted by most marine bacteria and animals (Campbell. 1970; Billen. 1984). Therefore, in areas of high biological activity and reduced mixing (such as in boundary layers near surfaces). NH, might reach levels high enough to induce settlement behavior in oyster larvae. Total (NH, + NH/) concentrations of 10 mA/ have been reported in interstitial waters from marine sediments (Bruland, 1983). Stevens (1983) found that total (NH, + NH4+) concentrations in association with oyster reefs may reach greater than 200 ^M in sediment waters and 3 nM in overlying waters 10 cm above the sediment interface. The presence of high levels of NH3 in the environment, the rapid induction of settlement behavior bv NH,, and the quick reversibility of inductive effects of NH,, strongly suggest that NH, is a natural environmental cue for re- cruitment of oyster larvae. Its actual involvement in larval recruitment, however, has not yet been demonstrated. If NH, is a natural inducer of settlement behavior, then it must be a relatively non-specific
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
