Alc. Wong et al., FACTORS AFFECTING THE DISTRIBUTION AND ABUNDANCE OF AN UNPIGMENTED HETEROTROPHIC ALGA PROTOTHECA-RICHARDSI, Freshwater Biology, 32(1), 1994, pp. 33-38
1. Numbers of the contramensal alga Prototheca richardsi were high in
spring in two ponds used for breeding by anuran amphibians, but lower
at other times of year and undetectable in two ponds not used by anura
ns. 2. Prototheca richardsi became abundant in the silt of eight exper
imental ponds which contained tadpoles, but remained undectable in fou
r otherwise identical ponds lacking tadpoles. 3. Prototheca richardsi
numbers in laboratory microcosms remained stable for many days in ster
ile tap water, but declined with a half-life of about 6 days in pond w
ater at 20-degrees-C. 4. Further studies with microcosms using antibio
tics and electron microscopy indicated that mortality of P. richardsi
was caused primarily by pathogenic bacteria.