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توجه ! این یک نسخه آرشیو شده میباشد و در این حالت شما عکسی را مشاهده نمیکنید برای مشاهده کامل متن و عکسها بر روی لینک مقابل کلیک کنید : Fossil diatoms and scales of Chrysophyceae in the recent history of Hall Lake, Washington



iranplant
29th January 2009, 01:58 PM
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C. S. MUNCH 1 <A href="http://www3.interscience.wiley.com/journal/119587887/abstract#c1">
1 Department of Biology, Hood College, Maryland, U.S.A.
Correspondence: C. S. Munch, Department of Biology, Hood College, Frederick. Maryland 21701, U.S.A.
Copyright 1980 Blackwell Science Ltd
ABSTRACT


SUMMARY. Scales of several members of the Chrysophyceae (family Synuraceae) were examined from a core of the recent sediments of Hall Lake, Washington, in conjunction with a study of fossil diatoms. Both types of microfossils revealed communities changing with the historical development of the lake. Increases in planktonic diatoms and in two species of Mallomonas occurred about the time of European settlement. Several acidophilous species among the Chrysophyta disappeared with the establishment of a sawmill and meromictic conditions in the lake. When extensive road construction around the lake ended the period of meromixis, the ratio of Synuraceae, in general, to diatoms, declined. Besides the change in ratio of Synuraceae to diatoms there was a change in the composition of the community of Synuraceae at that time. Species of Synura that had been rare before became the most abundant, and Mallomonas became relatively rare. Throughout the recent history of the lake the dominant Synuraceae seemed to respond more strongly to disturbance around the lake than the most abundant diatoms; thus, scales of Mallomonas, Synura, and other Synuraceae are valuable microfossils for paleolimnological studies.


Chrysophyceae


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A relatively large and diverse class of algae in the chlorophyll a–c phyletic line (Chromophycota). In protozoological classification, these organisms constitute an order, Chrysomonadida, of the class Phytomastigophora. Some workers align Chrysophyceae (golden or golden-brown algae) with Bacillariophyceae (diatoms) and Xanthophyceae (yellow-green algae) in the division Chrysophyta.

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