Intracapsular algae provide fixed carbon to developing embryos of the salamanderAmbystoma maculatum

Abstract

SummaryEach spring, North American spotted salamander (Ambystoma maculatum) females each lay hundreds of eggs in shallow pools of water. Eggs are surrounded by jelly layers and deposited as large gelatinous masses. Following deposition, masses are penetrated by a mutualistic green alga, Oophila amblystomatis, which enters individual egg capsules, proliferates, and aggregates near the salamander embryo, providing oxygen that enhances development. We examined the effects of population density of intracapsular Oophila on A. maculatum embryos, and show that larger algal populations promote faster embryonic growth and development. Also, we show that carbon fixed by Oophila is transferred to the embryos, providing the first evidence of direct translocation of photosynthate from a symbiont to a vertebrate host.