PRESQUE ISLE, Maine — Dr. Stuart R. Gelder, emeritus professor of biology at the University of Maine at Presque Isle, recently spent 12 days in Japan conducting research with two of his international colleagues. Dr. Gelder is one of the world’s leading researchers of branchiobdellidan annelid (crayfish worms).
The research team consisted of Gelder, Prof. Akifumi Ohtaka, a longtime colleague who teaches at Hirosaki University, Aomori Prefecture, in northern Honshu Island, and Prof. Itsaru Koizumi, at Sapporo University, Hokkaido Prefecture, Japan. Gelder’s visit was supported by a grant from the Watershed Ecology Research Fund of Japan to Ohtaka.
Japan has one native crayfish and that is now listed as endangered due in part to increased urbanization and the introduction of North American crayfishes. Japanese crayfish support 11 species of crayfish worms unique to northern Honshu and Hokkaido, whose futures are also in doubt. The current project was designed to collect samples of all the Japanese crayfish worm species so that two particular genes could be sequenced. These data will be used to ascertain their nearest relatives on the mainland (China and Korean Peninsula) and then how the various species evolved within Japan.
Gelder’s contribution was to remove live crayfish worms from the crayfish and identify the species by taking a semitransparent individual and examining it under a microscope at 200x magnification, then transferring a portion of the body with very fine tweezers to a plastic vial for subsequent molecular sequencing. He transferred the anterior portion into a separate vial for later mounting onto a permanent slide.
As some of the specimens were about a millimeter long, the process was challenging. The permanently mounted anterior body contains all the organs needed for species identification and it becomes the permanent reference for the subsequent gene sequences.
The current work is the first comprehensive distribution study of native crayfish worms since a published work in 1934. Initial results found crayfish at a number of sites but without worms, where previously they had been reported. Gelder said no reasons for these absences are apparent at the moment.
During Gelder’s visit, a typhoon passed over the island. Although it missed Sapporo, it devastated an area to the southeast where some of the most productive collecting sites for crayfish and their worms were completely washed away. He said monitoring the recovery of these areas will provide important information necessary to develop strategies to protect this species.
Gelder was invited to present a research seminar on crayfish worm biology to graduate students at Sapporo University. A crayfish expert and long-time colleague, Dr. Tadashi Kawai of Wakkanai Fisheries Experimental Station in Hokkaido, arranged for him to present “Friends of Crayfish” to the Hokkaido Prefecture conservation group, which is part of the Ministry of Land, Infrastructure, Transport and Tourism.
The visit to Japan provided an opportunity for Gelder and Ohtaka to discuss the latest draft of a manuscript describing the first record of a North American crayfish worm and other invasive species in Japan. This manuscript will be submitted to an international peer-reviewed journal for publication by the end of the year.
