Using post-settlement demography to estimate larval survivorship: a coral reef fish example

Area of Science:

• Ecology
• Evolutionary Biology
• Marine Biology

Background:

• Many species exhibit multi-stage life cycles with dispersive larval stages that are difficult to sample.
• Accurate quantification of survival during these early, dispersive phases is critical for understanding population dynamics and life history evolution.

Purpose of the Study:

• To develop and apply a novel method for estimating survival throughout unsampled, dispersive larval stages using demographic data from later life stages.
• To estimate average larval survivorship for the bicolor damselfish (Stegastes partitus) and compare it to existing models of larval mortality.

Main Methods:

• Utilized field measurements of post-settlement demography (growth, survival, reproduction) in bicolor damselfish.
• Applied a demographic model assuming lifetime reproductive compensation to estimate average larval survivorship.
• Compared the derived survivorship estimate with expected values based on published marine fish larval mortality rates.

Main Results:

• The study successfully estimated average larval survivorship for bicolor damselfish to be 0.108%.
• This estimate was approximately two orders of magnitude higher than expected based on average, size-dependent larval mortality patterns in marine fishes.
• The findings suggest that early larval mortality may deviate significantly from general patterns.

Conclusions:

• Demographic data from juveniles and adults can effectively estimate survival through unsampled dispersive larval stages.
• Larval survivorship in some species, like the bicolor damselfish, may be substantially higher than predicted by general mortality models.
• Understanding the nuances of early-stage larval mortality, particularly its scaling with body size, is essential for accurate ecological and evolutionary assessments.