Vol. 58, 2019
Latitudinal Difference in the Species Richness of Photosymbiotic Ascidians Along the East Coast of Taiwan
Euichi Hirose1,* and Yoko Nozawa2
of Chemistry, Biology and Marine Science, Faculty of Science,
University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan.
*Correspondence: E-mail: email@example.com (Hirose)
2Biodiversity Research Center, No. 128, Academia Road Sec. 2, Nankang, Taipei 115, Taiwan
(Received 29 January 2020 / Accepted 5 May 2020)
Communicated by Benny K.K. Chan
didemnid ascidians harbor cyanobacterial symbionts, and this is the
only obligate photosymbiosis system known in chordates. These
photosymbiotic ascidians are found only in tropical and subtropical
waters, probably because the photosymbionts are vulnerable to low
temperatures. We surveyed the photosymbiotic ascidian fauna on the east
coast of Taiwan. Present and previous reports show that 13 species have
been recorded in Taiwan, and the species richness and composition is
different in 5 areas along the east coast. On the middle-east,
southeast, and south coasts, 5 or more species have been recorded,
whereas only 1 species has been found on the northeast coast, and no
species have been recorded on the north coast. The gap in species
richness is probably related to the course of Kuroshio Current that
goes from south to north along the east coast of Taiwan but changes to
an easterly direction off the northeast coast. Increase in water
temperature due to global warming could cause northward expansion of
the distribution ranges of these ascidians in future. Hence, the
photosymbiotic ascidian fauna could be an environmental indicator in
subtropical, shallow water, and the present study provides a basic
dataset of the current status of photosymbiotic ascidians in Taiwan.
Key words: Biogeography, Coral reef, Didemnid ascidians, Cyanobacterial symbiosis, Latitude, Species diversity.
Hirose E, Nozawa Y. 2020. Latitudinal difference in the species
richness of photosymbiotic ascidians along the east coast of Taiwan.
Zool Stud 59:0t. doi:-.