Spatial and demographic consequences of nursery-dependence in reef fishes: an empirical and simulation study
Authored by John A B Claydon, Marta C Calosso, Leo Giulio A De, Rita B J Peachey
Date Published: 2015
DOI: 10.3354/meps11245
Sponsors:
No sponsors listed
Platforms:
R
Model Documentation:
Other Narrative
Model Code URLs:
Model code not found
Abstract
The rainbow parrotfish Scarus guacamaia has an obligate dependence on
mangroves at juvenile stages, and, as the largest herbivorous fish in
the Caribbean region, its distribution has important implications for
coral reefs. The effect of connectivity with mangroves on relative
density, biomass and size of S. guacamaia was assessed from over 65 km
of visual surveys from Bonaire, Caribbean Netherlands. In addition, an
individual-based, age-structured, mechanistic model (IBM) was developed
to explain dispersal patterns from nurseries for S. guacamaia. In the
IBM, mortality was constant, growth was determined by a von Bertalanffy
growth equation, and movement was modeled through a random walk process.
Using the IBM, simulations were run to generate patterns of density, biomass, and size with distance from nurseries. Rainbow parrotfish were
observed as far as 42 km away from the nearest mangroves on Bonaire.
Relative density and biomass showed significant exponential declines
with distance from the primary mangrove nursery and were significantly
higher in high versus low complexity non-mangrove habitats. Mean size
increased linearly with distance (r(2) = 0.74), reflecting an absence of
smaller individuals with greater distance. These results were closely
mirrored by the simulation study: density and biomass declined
exponentially with distance from nurseries, and size and age increased
following saturating functions. The results suggest that mangroves may
have the potential to supply individuals much further than previously
thought. Both the empirical and simulation studies reaffirm calls to
prioritise protection of reef habitats close to nurseries as well as the
nurseries themselves.
Tags
Phase-shifts
Caribbean coral-reefs
Grouper epinephelus-itajara
Seagrass beds
Cheilinus-undulatus
Rainbow parrotfish
Marine
nurseries
Shallow-water
Tropical reef
Age structure