Thermal history influences reproduction but not offspring quality in a coral reef fish

Tropical reef fish are especially sensitive to ocean warming, and the impacts of warming on reproduction may influence the persistence of future populations. The capacity of phenotypes to match altered conditions depends on the nature of environmental change, such as timing, duration, and variability. However, little is known about how these characteristics alter the plasticity of reproduction. The present study investigated how the timing of warming (+1.5°C above present-day temperature) through early development (hatching-1.5 yr) and/or post-maturation (1.5-3 yr) impacted reproduction and offspring quality in a tropical damselfish ( Acanthochromis polyacanthus ). Warming at both life stages affected adult morphometrics and reproduction differently, but offspring quality was not impacted by parental thermal experience. Specifically, warming during development resulted in smaller adults (shorter standard lengths) with significantly reduced fecundity, while warming after maturation led to lighter adults for a given length that produced smaller eggs. This study also highlighted that fish may be able to partially restore their reproductive output in elevated temperatures with extended experience of warming after maturation. However, negative impacts from developing in elevated temperatures remained even in their second breeding season when fish were 3 yr old. Such knowledge of how aspects of temperature change influence environmental sensitivity and the capacity for plasticity is important to understand the drivers of species’ resilience to change.