Sj. Kupferberg et al., EFFECTS OF VARIATION IN NATURAL ALGAL AND DETRITAL DIETS ON LARVAL ANURAN (HYLA-REGILLA) LIFE-HISTORY TRAITS, Copeia, (2), 1994, pp. 446-457
The quality of algae as food for larval Pacific treefrogs, Hyla regill
a, varies among algal taxa. Tadpole diets were manipulated in enclosur
es in the South Fork Eel River, northern California. Enclosed tadpoles
were fed ad libitum one of the dominant filamentous green algae (Clad
ophora, Zygnema, Mougeotia, or Oedogonium), the dominant cyanobacteriu
m in the habitat (Nostoc), flocculent detritus, or a commercial reptil
e/amphibian food. Tadpoles in a control treatment were not fed but had
access to seston which deposited in all enclosures. Diet treatment si
gnificantly affected weekly growth rates, as well as time to and weigh
t at metamorphosis. Tadpoles grew most rapidly on filamentous green al
gae with diatom epiphytes and on the commercial food. Tadpoles fed epi
phytized Cladophora metamorphosed 27.1% (11.7 days) sooner and weighed
38.9% (70 mg) more than tadpoles fed Cladophora cleaned of diatoms. I
n comparison to tadpoles fed Mougeotia, which does not support epiphyt
es, tadpoles fed epiphytized Cladophora metamorphosed 37.4% (19.7 days
) sooner and weighed 31.6% (50 g) more. Tadpoles with the lowest growt
h rates were those filtering deposited seston or flocculent detritus.
Observed changes in life-history traits with diet are assessed in rela
tion to models which predict the optimal timing of metamorphosis.