TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 57 (No. 1), pp. 105-107, 2001

Short Contribution

High Ash Content in Net-Plankton Samples from Shallow Coastal Water: Possible Source of Error in Dry Weight Measurement of Zooplankton Biomass

Norio Nagao1, Tatsuki Toda1, Kazutaka Takahashi2*, Koji Hamasaki3, Tomohiko Kikuchi4 and Satoru Taguchi1

1Faculty of Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan
2Tohoku National Fisheries Research Institute, 3-27-5 Shinhama-cho, Shiogama, Miyagi 985-0001, Japan
3Faculty of Applied Biological Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan
4Faculty of Education and Human Sciences, Yokohama National University, 79-2 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan

(Received 29 February 2000; in revised form 18 August 2000; accepted 18 August 2000)

Abstract: Annual examination of net-plankton biomass in dry weight, ash-free dry weight, organic carbon, and nitrogen weight at the Manazuru Harbor, central Japan revealed that net-plankton samples from shallow coastal water contained considerable amount of ash (53 ± 13% of dry weight) which would be caused by contamination of inorganic materials from re-suspension of sediments, terrestrial runoff and chain-forming diatoms. Therefore, in coastal water, dry weight is inadequate for determination of zooplankton biomass involving the possibility of over-estimation. Practical estimation of net-plankton biomass in shallow coastal waters, ash-free dry weight, organic carbon, and/or nitrogen are more adequate.


*Corresponding author E-mail: issey@myg.affrc.go.jp


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