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Demographic plasticity facilitates ecological and economic resilience in a commercially important reef fish

Citation

Taylor, BM and Choat, JH and DeMartini, EE and Hoey, AS and Marshell, A and Priest, MA and Rhodes, KL and Mekan, MG, Demographic plasticity facilitates ecological and economic resilience in a commercially important reef fish, Journal of Animal Ecology, 88, (12) pp. 1888-1900. ISSN 0021-8790 (2019) [Refereed Article]


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DOI: doi:10.1111/1365-2656.13095

Abstract

  1. Variation in life-history characteristics is evident within and across animal populations. Such variation is mediated by environmental gradients and reflects metabolic constraints or trade-offs that enhance reproductive outputs. While generalizations of life-history relationships across species provide a framework for predicting vulnerability to overexploitation, deciphering patterns of intraspecific variation may also enable recognition of peculiar features of populations that facilitate ecological resilience.
  2. This study combines age-based biological data from geographically disparate populations of bluespine unicornfish (Naso unicornis)葉he most commercially valuable reef-associated species in the insular Indo-Pacific葉o explore the magnitude and drivers of variation in life span and examine the mechanisms enabling peculiar mortality schedules.
  3. Longevity and mortality schedules were investigated across eleven locations encompassing a range of latitudes and exploitation levels. The presence of different growth types was examined using back-calculated growth histories from otoliths. Growth-type-dependent mortality (mortality rates associated with particular growth trajectories) was corroborated using population models that incorporated size-dependent competition.
  4. We found a threefold geographic variation in life span that was strongly linked to temperature, but not to anthropogenic pressure or ocean productivity. All populations consistently displayed a two-phase mortality schedule, with higher than expected natural mortality rates in earlier stages of post-settlement life. Reconstructed growth histories and population models demonstrated that variable growth types within populations can yield this peculiar biphasic mortality schedule, where fast growers enjoy early reproductive outputs at the expense of greater mortality, and benefits for slow growers derive from extended reproductive outputs over a greater number of annual cycles. This promotes population resilience because individuals can take advantage of cycles of environmental change operating at both short- and long-term scales.
  5. Our results highlight a prevailing, fundamental misperception when comparing the life histories of long-lived tropical ectotherms: the seemingly incongruent combination of extended life spans with high mortality rates was enabled by coexistence of variable growth types in a population. Thus, a demographic profile incorporating contrasting growth and mortality strategies obscures the demographic effects of harvest across space or time in N. unicornis and possibly other ectotherms with the combination of longevity and asymptotic growth.

Item Details

Item Type:Refereed Article
Keywords:Acanthuridae, biogeography, coral reef fish, ectotherm, growth plasticity, life span, mortality, unicornfish
Research Division:Biological Sciences
Research Group:Evolutionary biology
Research Field:Biogeography and phylogeography
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Assessment and management of benthic marine ecosystems
UTAS Author:Marshell, A (Dr Alyssa Marshell)
ID Code:150108
Year Published:2019
Web of Science® Times Cited:19
Deposited By:Sustainable Marine Research Collaboration
Deposited On:2022-05-24
Last Modified:2022-05-25
Downloads:0

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