REFUGIA AND RESILIENCE: VARIABLE POPULATION DEMOGRAPHICS AND REPRODUCTION OF A CORAL REEF FISH ACROSS VERTICAL SPATIAL SCALES
With the decline of coral reef ecosystems, reef organisms may become dependent upon habitats at the periphery of their distributions for population persistence. Mesophotic coral reefs (30-150 m), near the depth boundary of most reef fishes, may be natural refuges that can supply larvae to degraded reefs, and are buffered from anthropogenic and natural disturbances. However, depth-driven habitat variability can mediate the refuge function of mesophotic reefs by affecting demographic parameters that influence population resilience and connectivity. We compared population density and structure, size, growth, and reproduction of a model reef fish (bicolor damselfish: Stegastes partitus) across shallow shelf (<10 m) and deep shelf (20-30 m) reefs in the Florida Keys, and mesophotic reefs (60-70 m) at Pulley Ridge to assess the refuge function of peripheral habitats. As depth increased, populations were comprised of older and larger individuals, and density decreased, suggesting that mesophotic populations are limited by replenishment of young fish. Otolith-derived ages, measurements of oocyte area, and batch fecundity indicated that mesophotic fish reach larger asymptotic sizes, and have longer lifespans and higher reproductive investment than fish in shallower habitats. Reliance on long-lived individuals for population persistence may decrease ecosystem resilience, however, by supporting populations of large, long-lived individuals, mesophotic reefs may be important sources of larvae for shallow fish populations and may function as valuable refuges for future populations.
Goldstein, E. D., RSMAS, University of Miami, USA, email@example.com
D'Alessandro, E. K., RSMAS, University of Miami, USA, firstname.lastname@example.org
Sponaugle, S., Hatfield Marine Science Center, Oregon State University, USA, Su.Sponaugle@oregonstate.edu
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