The long and short of it: travel distance and territorial intruder pressure predict central-place spawning tactics among Caribbean Stegastes damselfishes.

Abstract

Central place activities present conflicting demands or tradeoffs between activities at and away from the central place. Stegastes damselfishes are small, mostly reef-associated fishes that are common in shallow tropical and sub-tropical marine environments. Both sexes defend a territory consisting of their food supply and shelter sites, with male territories also including a nest where females lay eggs which are then guarded by the male. Females therefore need to leave their territory to spawn in male nests, putting them at risk of attack during travel and leaving their territory exposed to intruders while away. Female egg-laying tactics can vary among and within species-some complete spawning during a single, extended bout, while others do so in multiple bouts, separated by visits to their territory. Spawning behavior and behaviors associated with territoriality of 101 individuals from 6 species were observed between June 2022 and May 2023 to identify and quantify the factors that influence variation in spawning tactics both within and among Stegastes species. Specifically, we tested two predictions of the hypothesis that dividing spawning with a single male into bouts allows individuals to balance the tradeoff between travel costs and intruder pressure for females of permanently territorial damselfishes: (1) intruder pressure will be positively related to the number of spawning trips among species and/or among females within species; and (2) travel distance will be negatively related to the number of spawning trips. Results of this study showed that Stegastes females increase their spawning bouts with an increase in intruder pressure and decrease their spawning bouts with an increase in travel distance.