Complex Species Interactions: Is Egg Predation a Hidden Threat to the Reproductive Success of an Endangered Fish Species?

When multiple species within an ecological community are all threatened or endangered, it may be crucial to understand the interconnected relationships of populations in order to better inform their individual recovery plans. We examined the potential egg predation of the critically endangered Leon Springs Pupfish (Cyprinodon bovinus) endemic to the Diamond Y Spring system in West Texas. This one spring-fed pool also includes multiple species of invertebrate animals and another endangered fish, the Pecos Gambusia (Gambusia nobilis). Artificial mats were used to observe individual eggs laid by promiscuous females within the defended territories of various males. These eggs were then monitored over a 24-hour period, with and without protection from nocturnal predators. Analysis revealed that predation of eggs is occurring both diurnally and nocturnally, and examination of the pattern of egg predation suggests that this egg predation is a result of multiple species of predators. The number of eggs at the beginning of the observation period was significantly correlated with the number not preyed upon and present following 24 hours, suggesting that males should be investing considerably in spawning with females to increase their reproductive output. Further study is needed to understand the impact that egg predation is having on the reproductive success of this endangered pupfish.