We got aboard the TS Nansei Maru this week to conduct the research voyage in Osumi Strait, northern end of the Ryukyu Archipelago. We had measured vertical gradient of the underwater light intensity, temperature and salinity using CTD at some sites off Mageshima Island and Kagoshima Bay. We had also collected the sand sample of sea floor using the bottom sampler. On the way back to Kagoshima Bay, we also observed the presence of drifting seaweed (
Sargassum horneri).
鹿児島大学水産学部附属練習船南星丸に乗船し、鹿児島湾と大隅海峡で調査航海を実施しました。調査の内容は水中光量や水温、塩分の鉛直分布の観測、採泥と（漸深帯の）海藻採取、行き帰りの流れ藻観察です。
On the sampling site, we used the CTD that can be measured automatically light, temperature, salinity, pH and dissolved oxygen. Especially, underwater light data is essential for our study. After this voyage, students will be calculating the consumption coefficient of PAR.
調査海域では，CTDを用いて光，水温，塩分，pH，溶存酸素濃度を測定します。漸深帯に生育する海藻群落に届く光量が知りたいので，光量については実測値を基に消散係数を算出し，任意の水深と光量を求めます。
Two students (left) are just now operating the CTD. Mr Fukuda of the first mate of Nanseimaru (right) is kindly supporting its operation. Actually, it is "research" for us, but is carried out as the practical class of training voyage (credit 1) for students. After the measurement, we collected sand on the seafloor using the bottom sampler.
学生がCTDの操作を練習しています。
This is the photo of Mageshima Island that is located on the offshore of western part of Tanegashima island. It was taken at the sampling site. Depth of the site was around 35m, seafloor is thought to be mostly flat from here through the shore.
調査海域は種子島の西方沖にある馬毛島です。望遠で撮ってこのように見えるくらい沖にいますが，水深は約35mです。ここから島までゆるやかに浅くなる平坦な海底です。
After the survey, due to the occurrence of spring storm, we canceled a stop at the port of Nishinoomote, Tanegashima Island, and came back to Kagoshima Bay. Next day, measurements were conducted at some sites of Kagoshima Bay.
急速に発達した低気圧を避けるため，種子島の西之表港への寄港は断念し，調査後は鹿児島湾に戻ってきました。翌日は鹿児島湾内でCTDと採泥を行いました。
Deckhand is just checking the status of bottom sampler.
甲板員の方が採泥器のケーブルを握って採泥器の状況を探っています。
Sample was collected.
海底の砂がとれました。
海藻研の新入生のオリエンテーションも兼ねた航海でしたが，晴天時の光量データがバッチリとれました。次の航海は7月です。
