Vol. 36 No. 1, 1997
Sympatric Spawning of the Damselfishes Chromis fumea and Pomacentrus coelestis on the Northern Coast of Taiwan
Inst.of Zoology, Academia Slnice, Taipei, Taiwan 115
Rong-Quen Jan (1997) The damselfishes Chromis fumea and Pomacentrus coelestis are both free-ranging demersal spawners; they generally do not occupy a permanent substrate. A total of 2149 nests of C. fumea and 890 nests of P. coelestis
were found in the study area on the northern coast of Taiwan in the
spawning season of 1986. Both species spawned in groups. Sympatrie
spawnings, which involved about 1/3 of C. fumea nests and 12.1 % of P. coelestis nests, occurred at some of the spawning sites. The 2 damselfish species nested mainly on different substrates: C. fumea on open substrate, with P. coelestis
in small burrows or depressions excavated beneath boulders. However,
interference occurred whenever they spawned sympatrically. When
the interactions involved only 1 individual of each species, C. fumea
(which is larger in size and built nests first) was able to prevent
the competitor from building a nest in the neighboring area by
active aggression. In comparison, when the 2 species encountered each
other in groups, harassment from P. coetestis was observed to force C. fumea to abandon their nests. P. coelestis Subsequently built nests at the site taken over from the latter fish.
Key words: Nesting substrate, Pomacentridae, Resource partitioning, Spawning season.
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