11th ICRS Abstract book - Nova Southeastern University

14-55
The Importance Of Behavior On Self-Recruitment: A Modeling Approach
Jean-Olivier IRISSON* 1 , Claire PARIS 2 , Laurent CHERUBIN 2 , Michel DE LARA 3 ,
Serge PLANES 1
1 UMR 5244, Biologie et Ecologie Tropicale et Mediterranenne, Université de Perpignan,
Perpignan, France, 2 RSMAS - University of Miami, Miami, FL, 3 CERMICS - Ecole des
Ponts et Chaussées, Paris, France
All early models of the pelagic phase of coastal organisms made the simplifying
assumption that larvae could be treated as passive particles in a flow. This was justified in
the early nineties because of both computational limitations and lack of knowledge about
the behavioral ecology of marine larvae. However, for more than a decade now, the
swimming abilities of coral reef fishes, in particular, as well as their vertical distribution,
have been investigated using several methods. All agree on the tremendous swimming
speeds and endurance displayed by fish larvae, on their ability to influence their vertical
and horizontal distributions and on the potential impact of these factors on connectivity.
Yet, no numerical model integrates this kind of behavior more extensively than for the
last instants of larval life.
We present two numerical models of the whole larval phase which both feature larval
behavior. One explicitly integrates larval swimming in a mesoscale environment, around
an island, and estimates the impact of swimming on self-recruitment. Because we still
know very little about the orientation behavior of larvae in oceanic waters, we deduce
their swimming decisions from an optimization method with realistic constraints and a
biologically sensible objective (i.e. recruitment). Swimming along these optimal
trajectories substantially enhances the possibility of self-recruitment compared to a
passive scenario. The other model examines the influence of statistically modeled vertical
distributions of larvae in the context of many inter-connected fish populations in the
Caribbean. The distribution is shown to markedly modify the connectivity matrix.
Overall, both models show that larval behavior has a great influence during the pelagic
phase. Many studies show that larvae probably use their swimming abilities to reduce
rather than to enhance dispersal, and our findings demonstrate that they can do so very
efficiently.
14-56
Long PLDs, Larval Behavior, and Connectivity in Spiny Lobster
Mark BUTLER* 1 , Robert COWEN 2 , Claire PARIS 2 , Hirokazu MATSUDA 3 , Jason
GOLDSTEIN 4
1 Department of Biological Sciences, Old Dominion University, Norfolk, VA, 2 Rosenstiel
School of Marine & Atmospheric Sciences, University of Miami, Miami, FL, 3 Fisheries
Research Division, Mia Prefecture Fishery Research Center, Mia, Japan, 4 Department of
Zoology, University of New Hamphire, Durham, NH
Among marine taxa, the pelagic larval duration (PLD) of spiny lobsters lies at the
extreme. With PLDs ranging from 4 to 24 mos, spiny lobster larvae potentially disperse
thousands of kilometers unless they possess behaviors or are captured in retentive
environments that constrain their transport. Attempts to model connectivity in spiny
lobsters have been hampered by a poor understanding of PLDs, ontogenetic changes in
behavior, and by overly simplistic models. We have combined laboratory and field
studies of larval behavior and distribution with advanced oceanographic modeling to
predict dispersal of Caribbean Spiny Lobster (Panulirus argus). We successfully, and for
the first time, reared P. argus from egg to juvenile and have determined its PLD (6 mos)
along with stage-specific responses of larvae to light and chemical cues that may affect
dispersal. Our experiments revealed distinct differences in response among larval stages
consistent with observations of larval vertical distribution in nature, determined from
monthly depth-stratified plankton tows. We also discovered that the strong-swimming
postlarvae are attracted to coastal chemical cues up to 30 km from shore, particularly
cues emanating from red macroalgae. These data have been used to parameterize a
lobster Lagrangian particle model linked with the Hybrid Coordinate Ocean Model,
similar to methods used for fishes. Simulations of P. argus larval dispersal suggest that
with larval behavior: (a) the probability of successful recruitment increased by more than
an order of magnitude, (b) median dispersal was ~200 km compared to ~ 800 km in
simulations using passive dispersal, and (c) local patterns of retention and advection of
larvae were idiosyncratic. We are now determining if model predictions of recruitment
magnitude are consistent with empirical estimates of larval supply in the Caribbean.
Oral Mini-Symposium 14: Reef Connectivity
14-57
Combining Modeling And Empirical Approaches To Track Connectivity Across
Temporal And Spatial Scales
Heather GALINDO* 1 , Donald OLSON 2 , Stephen PALUMBI 1
1 Hopkins Marine Station, Stanford University, Pacific Grove, CA, 2 Rosenstiel School of Marine
and Atmospheric Sciences, University of Miami, Miami, FL
Biological connections among marine populations via larval dispersal affect both demographic
and evolutionary processes, yet describing the actual patterns of connectivity has remained a
challenge. Recent integration of oceanographic and population genetic models has proven an
effective tool for generating hypotheses about connectivity patterns we can then test with
empirical datasets. We will present examples of this approach at various scales and discuss the
advantages and limitations of this method in each case. First, we will describe how this
approach has been successfully used to detect major geographic breaks in genetic structure for a
free-spawning coral at the scale of the Caribbean basin. Next we will outline how this approach
can be modified for application at both smaller spatial and temporal scales. Smaller spatial
scales can potentially be achieved through finer geographic resolution of oceanographic models
coupled with local collection of empirical data. In addition, better temporal resolution can be
gained by matching recent oceanographic datasets with a cohort genetics approach where the
genetic signatures of arriving larvae are tracked both within and between settlement seasons.
The explicit integration of oceanography and population genetics gives us a powerful way to
both generate and test hypotheses about patterns of marine connectivity. In addition, this
modeling framework is extremely flexible and can be adapted to a variety of geographic regions
and marine species.
14-58
Realized Connectivity: Post-Settlement Survival Linked To Larval Source
Scott HAMILTON* 1 , Robert WARNER 1
1 EEMB, UCSB, Santa Barbara, CA
Experiences during larval life may influence phenotypic traits, performance, and the probability
of post-settlement survival. For a reef fish on an oceanic island, we used otolith (ear stone)
elemental profiles of lead (Pb) to assign recent settlers to (1) a group that developed in
nearshore waters elevated in Pb, or (2) those that developed in offshore waters depleted in Pb,
potentially dispersing from upstream sources. Larval history influenced early life history traits:
offshore developers initially grew slowly but compensated with fast growth upon entering
nearshore waters, and metamorphosed in better condition with higher energy reserves. While
45% of settlers developed nearshore, only 23% of survivors after the first month displayed a
nearshore otolith profile. Importantly, selective mortality was mediated by larval history, in that
the post-settlement intensity of selection was much greater for fish that developed nearshore,
potentially because only exceptionally strong offshore larvae survived to settle in the first place.
Given the potential for asymmetrical post-settlement survival based on larval history, successful
management may require knowledge of ‘realized connectivity’ on ecological scales, which is
the proportion of individuals from different sources that survive to reproduce. Simply counting
new settlers may be misleading.
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