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Vol. 48 No. 5, 2009
Plasticity of Feeding Habits of Two Plectroglyphidodon Damselfishes on Coral Reefs in Southern Taiwan: Evidence from Stomach Content and Stable Isotope Analyses
Cheng-Tze Ho1, Yi-Cheng Fu1,2, Chi-Lu Sun2, Shuh-Ji Kao3, and Rong-Quen Jan1,*
1Biodiversity Research Center, Academia Sinica, Nankang, Taipei 115, Taiwan
2Institute of Oceanography, National Taiwan University, Taipei 106, Taiwan
3Research Center for Environmental Changes, Academia Sinica, Nankang, Taipei 115, Taiwan
Cheng-Tze Ho, Yi-Cheng Fu, Chi-Lu Sun, Shuh-Ji Kao, and Rong-Quen Jan (2009) W.On
the west bank of the intake bay of a nuclear power plant at Nanwan,
southern Taiwan, a recent outbreak of sea anemones has eliminated most
branching corals at the site. In this habitat currently dominated
by sea anemones, the abundance of Dick’s damsel, Plectroglyphidodon dickii Lienard 1983, has increased more markedly than the sympatric congener, P. johnstonianus Fowler and Ball 1924. To study whether the distribution patterns of the 2 Plectroglyphidodon
damselfishes were underlain by food availability and feeding habit
plasticity, the reef area in the embayment was divided into 2 different
zones, zone A dominated by Acropora corals and zone B dominated by a
sea-anemone, and both stomach content and stable isotope analyses were
used to delineate feeding habits of these 2 damselfishes in these 2
zones. Stomach contents showed that the major food items for P. dickii
in zone A were filamentous algae (33.4%) and coral polyps (22.3%),
while in zone B, they were filamentous algae (35.8%) and sea anemones
(28.2%). In contrast, coral polyps were the major food item for P. johnstonianus
in both zones (accounting for 75.5% in zone A and 67.5% in zone
B). Analyses of δ 13C and δ 15N values concurred that coral
polyps were the major nutrient source of P. johnstonianus. In addition, the contributions of both coral polyps and sea anemones to P. dickii
were verified. Overall, it was postulated that in the sea
anemone-dominated habitat, sea anemones were substituted for coral
polyps in the diet of P. dickii, but similar plasticity did not occur in P. johnstonianus. Thus the higher feeding plasticity of P. dickii might have made it possible to more-successfully immigrate to the newly developed habitat.
Key words: Plasticity, Sea anemone, Coral polyp, Damselfish, Stable isotope.
*Correspondence: Tel: 886-2-27899519. Fax: 886-2-27858059. E-mail:rqjan@gate.sinica.edu.tw
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