| Popis: |
The reproductive biology of three species of rainbowfish (Mel- University, Nathan, Queensland, Australia anotaeniidae) in northeastern Australian rainforest streams was investi- gated. Two species, Melanotaenia eachamensis and Cairnsichthys rhom- bosomoides are endemic to the area, whereas the third, M. splendida splen- dida, is more widespread. The species were all highly fecund, producing many hundreds of eggs between 1.10 and 1.24 mm in diameter. Melanotae- nia eachamensis was the most fecund, produced the largest eggs of the three species, and consequently exhibited the greatest maternal investment (as measured by gonadosomatic index). The majority of reproductive ef- fort occurred during the dry season, although reproductively active fish were present year-round for each of the species, but particularly so for M. s. splendida and C. rhombosomoides. No evidence for a role by tempera- ture or photoperiod as environmental cues for reproduction was found, and it was suggested that gonad development was strongly tied to so- matic growth. The concentration of reproduction to the dry season en- sures that larvae are produced during a period of relatively stable and be- nign physical conditions. Comparison of temporal changes in gonadoso- matic index values suggest that the spawning season of M. eachamensis |
Plný text