Title: HABITAT AVAILABILITY AND DEPTH-DRIVEN POPULATION DEMOGRAPHICS REGULATE REGIONAL REPRODUCTIVE OUTPUT OF A COMMON CORAL REEF FISH

Abstract: Coral reef organisms that span broad geographic and depth distributions experience a range of habitat quality, creating variable subpopulation demographics and dynamics. At the depth boundary of coral reefs, mesophotic coral ecosystems (30-150 m) that are buffered from anthropogenic stressors may be refuges that can seed larvae to degraded coral reefs. However, the degree of connectivity via larval production is restricted by population size and reproductive output of organisms at the periphery of their distributions. We incorporated population density, benthic habitat, and depth-stratified population demographics of a model reef fish (the damselfish Stegastes partitus) to assess subpopulation egg production across regions that encompass the depth distribution of the species: Florida Keys (FK: 0-35 m depths) and Pulley Ridge (PR: 60-100 m). Subpopulation densities and abundance peaked at mid-depths (10-20 m) and declined as depth increased. Egg production followed a similar pattern, but was considerably affected by differences in fish size, sex ratios, and probability and frequency of spawning across depths. Despite low population densities on mesophotic reefs, the expansive reef area at PR resulted in a subpopulation size that comprised 20% of the regional population and 14% of the total reproductive output across the study region. Our results indicate that mesophotic reefs may be important sources of larvae, and that habitat availability and depth-driven population demographics have substantial effects on reproductive output across geographic regions and depths.

Authors: Sponaugle S, Goldstein E, D’Alessandro EK

Presentation: Poster (#189)

Session: 15

Date: 06/21/16

Time: 18:15 - 19:45

Location: Poster/Exhibit Hall

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