11th ICRS Abstract book - Nova Southeastern University

14-59
Fishy Chronology: Using The Chemical Chronology Of Otoliths To Investigate
Shared Environments Among Reef Fish
Paul CHITTARO* 1 , J. Derek HOGAN 2
1 NWFSC, NOAA, Seattle, WA, 2 GLIER, University of Windsor, Windsor, ON, Canada
Understanding the extent to which populations are connected is necessary for effective
management. Although it is difficult to directly track fish during their pelagic larval
stage, their otoliths have proven to be an invaluable tool since they record not only the
time but also aspects of the environment in which the fish resides. The goal of this study
is to provide information regarding the environments through which fish traveled, as well
as the number of source populations that supply reef fish. To do this we use the otoliths
of newly settled bicolor damselfish (Stegastes partitus), that were collected from Belize
and Mexico in 2002 and 2003, and we determine the concentrations of elements (via laser
ablation) along a transect from the otolith core to edge (representing their larval
development and pelagic dispersal, until their settlement). We compare otolith chemical
chronologies of individuals (at the site and regional scale, as well as at different time
periods) in order to identify the extent to which individuals occupied similar
environments during the course of their lives and the number of source populations from
which they originated.
14-60
Multiple Scales Of Larval Dispersal in A Coral Reef Fish
Mark TUPPER* 1
1 The WorldFish Center, Penang, Malaysia
The management of coral reef fisheries is increasingly turning to an ecosystem-based
approach involving networks of marine protected areas (MPAs). Central to this approach
is knowledge of the connectivity between potential MPA sites. Recent studies have
demonstrated high levels of retention in pomacentrids, which lay demersal eggs and have
a short (9-21 days) planktonic phase. In this study, tetracycline was used to mass-mark
goatfish (Parupeneus multifasciatus) embryos, taken by stripping ripe adults captured
from a spawning aggregation site in Guam. This species has a planktonic phase of
approximately 35 days. Marked fish were then recaptured by beach seining for newly
settled juveniles and their otoliths examined for evidence of a tetracycline mark. A total
of 11,000 otoliths were sampled, and 17 displayed a clear tetracycline mark. Goatfish
settled over a range of dispersal scales. Some fish settled just tens to hundred of meters
from the aggregation site. Most fish settled 1 km to 10s of km from the aggregation. Two
fish settled about 100 km away at the downstream island of Rota in the Northern
Marianas Islands (NMI). This has implications for transboundary management, as it is
now evident that some of the NMI's reef fish stocks originate in Guam.
Oral Mini-Symposium 14: Reef Connectivity
14-61
Connectivity Of Coral Reef Fish Populations: Estimates From Transgenerational Mass-
Marking Of Embryonic Otoliths Using Enriched Stable Isotopes
Simon THORROLD* 1 , Geoffrey JONES 2 , Serge PLANES 3
1 Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 2 School of
Marine and Tropical Biology, James Cook University, Townsville, Australia, 3 Laboratoire
Écosystèmes Aquatiques Tropicaux et Méditerranéens, CNRS-EPHE-UPVD, Université de
Perpignan, Perpignan, France
Theoretical studies suggest that connectivity plays a fundamental role in the dynamics,
community structure, genetic diversity, and resiliency to human exploitation of coral reef fishes.
Modeling efforts have been hindered, however, by the paucity of empirical estimates of, and
processes controlling, population connectivity in coral reef ecosystems. While progress has
been made with older life stages, connectivity as a function of larval dispersal remains
unresolved for most marine populations. We have developed a new technique, based on
transgenerational marking of embryonic otoliths with enriched barium isotopes, to quantify
population connectivity in coral reef fishes. Gravid females are injected with an enriched stable
Ba isotope solution that generates a unique isotope signature in the otoliths of all larvae
subsequently spawned by the individual for up to 3 months after the injection. Otoliths of
juvenile fish are then scanned for the tag using laser ablation inductively coupled plasma mass
spectrometry. Validated in benthic and pelagic spawning fishes, the first field study using
transgenerational marking has recently being completed in Kimbe Bay, on the northern coast of
New Britain, Papua New Guinea. Results suggest that natal homing of larvae may be a
common life history strategy in reef fishes, and thus appropriate spatial scales for management
and conservation of coral reefs are likely much smaller than previously realized.
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