11th ICRS Abstract book - Nova Southeastern University

14-10
Does Vertical Migration Behavior Of Reef Fish Larvae Influence Their Transport?
Klaus HUEBERT* 1 , Su SPONAUGLE 1 , Robert COWEN 1
1 Division of Marine Biology and Fisheries, University of Miami / RSMAS, Miami, FL
The degree to which the population connectivity of coral reef organisms is influenced by
the behavior of their dispersive larvae is controversial. One type of behavior that
potentially affects larval transport is vertical migration between depths with different
ambient currents. Our objective was to describe vertical migrations of pelagic coral reef
fish larvae in the Straits of Florida, and estimate their influence on larval transport.
Repeated time series of plankton net tows were conducted offshore of Miami using a
Multiple Opening Closing Net and Environmental Sensing System (MOCNESS). The
upper 100 m of the water column was sampled at 3 h intervals for a duration of 48 h, with
different nets fishing at 0-25 m, 25-50 m, 50-75 m and 75-100 m. Simultaneously, a suite
of environmental variables was recorded by the MOCNESS as well as a shipboard
Acoustic Doppler Current Profiler (ADCP). Across several families of reef fishes, large
larvae were distributed significantly deeper than small larvae, revealing downward
vertical migration with ontogeny. Taking ambient light levels and visual net-avoidance
behavior into account, vertical distributions of some families also varied significantly
between day and night, revealing diel vertical migrations. The predominant long-shore
component of the Florida Current was consistently greatest at the surface and decreased
with depth, while the cross-shore current was an order of magnitude weaker and highly
variable. The distribution of currents together with the observed patterns of vertical
migration of larvae results in an overall reduction of larval horizontal advection speeds,
with important consequences for population connectivity.
14-11
Homing in Coral Reef Cardinalfish Contributes to Low Population Connectivity
Among Reefs
Naomi GARDINER* 1 , Geoff JONES 1
1 ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville,
Australia
Recent studies have indicated greater levels of self-recruitment within coral reef fish
populations, and less connectivity among populations than once appreciated. However,
the ability of individuals to return to home reefs, and the spatial scales over which
homing can occur are poorly understood. While cardinalfish are known to return home
when displaced within lagoon environments, whether or not they can return home across
open water, when displaced from one reef to another is unknown. This study employed
displacement experiments to investigate the homing-ability of 5 common Indo-Pacific
cardinalfish species (Apogon fragilis, A. leptacanthus, Archamia zosterophora,
Ostorhinchus artus and O. quinquelineatus) in Kimbe Bay (PNG). Individuals were
displaced ca. 500m from ‘home’ positions onto either the same reef or onto a neighboring
reef (separated from the home site by open-water). Despite their small size (SL ca.
5-8cm) and limited swimming capabilities, all species were capable of returning to home
coral heads, across open-water, within a single night. Homing capabilities from up to
5km away were also demonstrated. We argue that homing in these nocturnal foraging
species contributes to the lack of connectivity among coral reefs.
Oral Mini-Symposium 14: Reef Connectivity
14-12
The Biology Of Acropora Palmata Larvae: Implications For Dispersal And Population
Connectivity
Ainhoa LEON ZUBILLAGA* 1 , Alina M. SZMANT 2,3
1 Biologia de Organismos, Universidad Simon Bolivar, Caracas, Venezuela, 2 Center for Marine
Science, University of North Carolina Wilmington, Wilmington, NC, 3 Center for Marine
Science, University of North Carolina Wilmington, Wilmington
The exchange of genetic material within and across coral populations will depend not just on
physical factors (e.g. hydrography) but also on larval characteristics such as buoyancy, duration
of development to competency and competency, swimming abilities, and other larval behaviors.
A range of experimental procedures were used to determine these variables for the threatened
species Acropora palmata. Eggs are buoyant upon release and rise to the ocean surface;
embryos lost buoyancy over time as they developed into planulae (F = 46.4, df = 9; p = 0.000)
presumably as they metabolized lipid stores. Embryos reached a swimming planula stage at ca.
60 h after fertilization, and gradually gained the ability to swim downwards; however,
maximum swimming capabilities were not observed until 192 h after fertilization. There was no
evidence of diel swimming patterns as was previously found for Montastraea faveolata. Larvae
did not reach competency until they were at least 6 to 8 days old. These larval characteristics
could lead to fairly extensive dispersal depending on local current conditions during the first
week after spawning. There was a significant dependence (x2 = 29.7, p