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41.
Fish abundance is often better predicted by microhabitat variables on continuous reefs than on isolated patch reefs. Although
this was suggested to stem from reduced post-recruitment relocation, this has not been shown experimentally. We found the
relationship between the presence of a coral-dwelling fish, Dascyllus marginatus, and the size of its coral host to differ between corals on continuous reefs and the sparsely distributed corals on sandy
bottoms. Empty transplanted corals were colonized exclusively by new recruits when on the sandy bottom, and both by new recruits
and post-recruitment dispersal of adults when on the continuous reef. New recruits settled predominantly into small corals,
although analyses of recruitment patterns were confounded by low recruitment in the studied years. Both tank experiments and
field survey data suggest that the presence of recruits in small corals is at least partially driven by predation by the dottyback,
Pseudochromis olivaceus, which lives predominantly in large corals within both habitats. Consequently, we suggest that the relationship between fish
presence and coral size differs between the habitats due to coral size dependent predation on recruits and variability in
the importance of direct recruitment to replenish fish populations. 相似文献
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R. Achiron MD Z. Gottlieb Y. Yaron M. Gabbay U. Gabbay S. Lipitz S. Mashiach 《黑龙江环境通报》1995,15(2):155-160
Our objective was to establish nomograms for fetal eye measurements from 12 weeks' gestation by using transvaginal and transabdominal high-resolution ultrasound techniques. A prospective cross-sectional study was performed on 450 normal singleton pregnancies between 12 and 37 weeks' gestation. Vitreous and lens circumferences were measured by transvaginal ultrasonography until 17 weeks, and by abdominal ultrasound between 18 and 37 weeks' gestation. Regression analyses were used to create nomograms, and several transformations were done to obtain linearity. Eye measurements of 12 fetuses at risk for ocular disturbances were plotted on the constructed nomograms. Linear relationships were fitted between vitreous (r2=0.79) and lens (r2=0.88) circumferences and gestational age. In addition, there was a significant correlation between these measurements and the biparietal diameter. Data of the fetuses at risk showed that disturbances in ocular growth were associated mainly with abnormal cerebral development. These normative data may be helpful in the prenatal diagnosis of suspected congenital syndromes that include, among their manifestations, ocular growth disturbances such as microphthalmos and anophthalmos. 相似文献
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