Copepods are major components of zooplankton community over the world oceans. They have important roles to transfer primary production to higher trophic levels of marine ecosystems. In general, secondary production can be estimated by animal body weight multiplying growth rate. Animal body weight has been accurately measured, but there is little information which method is relevant for estimation of growth rate. Thus, we have little knowledge on confidence of secondary production compared with that of primary produc tion. In the present study, we review methods to measure growth rate for natural popula tion of pelagic copepods and indicate the assumptions, the advantages and disadvantages. Seven methods have been used for measurements of growth rates of natural copepod population; natural cohort, artificial cohort, moult rate, egg production, nucleic acids ratio, enzyme activity and empirical models. Each method has specific assumptions and advantages/disadvantages dependent on environmental conditions and ecological properties of copepods. Because there is no method to be applied for all copepods, it is important to select some methods with compensation between the advantages and the disadvantages and to compare the growth rate estimates.

A design of a simple tide gauge, which cam be made easily and at a relatively low price, is proposed to observe readily sea-level fluctuations at multiple stations accompanying various coastal phenomena. This gauge is composed of a depth meter of a pressure sensor and a tube of 4 mm diameter and 9 m length as a damper of high frequency waves. Those are contained in a PVC pipe.

High frequency waves of period shorter than 30 seconds are cut off or reduced to mag nitude within 10% of wave heights, but waves of period longer than 1 hour are passed with delay time from 1 to 1.5 minutes. Comparing with the data of an authorized tide gauge station and observations at three stations around the Funka Bay, Hokkaido, Japan showed that this simple gauge can be used sufficiently in studies and researches on coastal oceanography.

The desirable water quality standard in the coastal sea cannot be decided by only the oceanographer. At first the working group must be established, which consists of the managers, stakeholders and scientists (not only natural but also social scientists), and the desirable water quality standard will be decided after long discussion among them. The scientific problem demanded to the oceanographer and his role in such working group are discussed in this paper.