Dear MARMAM colleagues,
We are pleased to share with you our recent publication in Biological
Conservation.
Chan SCY, Ho Y-W & Karczmarski L. (2024). Reproductive dynamics of an inshore
delphinid reflect demographic consequences of large-scale coastal
constructions. Biological Conservation, 297, 110690.
Abstract:
In fast-developing regions, rapid coastal urbanization has led to considerable
transformation of both landscapes and seascapes, with various adverse
implications for species dependent on inshore habitats. As reliable estimates
of vital demographic rates reflect the population-level responses to stressors,
rigorous quantification of these parameters is central to assessing the
consequences of human-induced environmental change. As a case-in-point, we
quantified the reproductive parameters and calf survivorship of an obligatory
inshore delphinid, the Indo-Pacific humpback dolphin (Sousa chinensis), in the
anthropogenic seascape of Hong Kong prior and during two consecutive
large-scale coastal infrastructure projects. Our 8-year photo-ID mark-recapture
dataset was examined with both frequentist and Bayesian techniques. The
reproductive output of female dolphins worsened significantly following the
onset of construction activities, eventually declining alarmingly close to
zero. Annual recruitment rate followed a similar trajectory. Concurrently, calf
survival rates (pooled across the study period) were low, with <60% of newborns
surviving the first 3-month and <46% surviving their first year of life. Both
mean crude birth rate (~0.03) and annual recruitment rate (~0.02) were among
the lowest reported for coastal delphinids to date. Cumulatively, all of this
slows population recruitment and increases population susceptibility to
stochastic events. We conclude that natural factors alone are not likely to
cause such critically low demographic rates, underscoring the vulnerability of
obligatory inshore species to growing anthropogenic pressure and habitat loss
in fast-changing coastal seas. We emphasize the need for proactive (instead of
reactive) conservation based on reliable sentinel model system and wise use of
the precautionary principle.
The article will be freely available (free to download) through this link until
24 September 2024:
https://authors.elsevier.com/a/1jYgJ1R%7EeWaRO
Please contact mailto:[email protected] if you have any questions
or if you need a PDF copy after the abovementioned expiry date.
Best regards,
Stephen
Stephen C.Y. Chan, PhD
Research Scientist
Cetacea Research Institute, Hong Kong
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