The Implications of the Target-Area Hypothesis on the Population Dynamics of the Spotted Spiny Lobster, <i>Panulirus guttatus</i>

<p>The target-area hypothesis, based on the theory of island biogeography, predicts that larger islands are more effective at intercepting passive immigrants. Most marine invertebrates have meroplanktonic larvae and open population dynamics, so immigration to populations in isolated benthic habitats is primarily by pelagic larval recruits. Thus, recruitment to isolated habitat “islands” may be more continuous and predictable on large islands than on small ones. Consequently, populations on large islands should not only be larger than those on small islands, but should also have more evenly distributed size structures. These differences in size structure among populations in isolated habitats of differing size could have profound impacts on the local reproductive success of species if mating is size-dependent or if fecundity is related to male or female size.</p> <p>I used laboratory experiments and field observations to test these predictions of the target-area hypothesis by determining if patch reef size influences the size structure and reproductive success of isolated populations of the spotted spiny lobster, <em>Panulirus guttatus</em> in the Florida Keys, Florida (USA). In chapter I, I provide a general introduction to the problem. Chapter II describes how growth and size-at-maturity of <em>P. guttatus</em> in isolated populations on coral patch reefs may be impacted by trade-offs with predation, food limitation and reproduction. In Chapter III, I explore the mating dynamics of <em>P. guttatus</em> as a function of different population size structure distributions that might occur on small and large patch reefs. Finally, in Chapter IV I examine the population size, size structure, and reproductive success of <em>P. guttatus</em> on patch reefs of varying size. Chapter V is a synopsis of these studies.</p> <p>I found that the growth of <em>P. guttatus</em> declined significantly with the onset of reproductive activity. Although this species matures at a small size, its age-at-maturity is similar to other spiny lobster species in comparable environments. Male <em>P. guttatus</em> compete for mates, but it is female choice that establishes the size assortative mating system I observed in this species. Fecundity is positively related to both male and female size, which suggests that fertilization success may at times be limited by sperm availability.</p> <p>The abundance of <em>P. guttatus</em> increased with reef size and population size structure was more evenly distributed on larger reefs, as predicted by the target-area hypothesis. Total reproductive output for local populations increased significantly with reef size, but more importantly reproductive output (i.e., success) was significantly more variable on small reefs. For isolated populations with limited immigration and size-dependent fecundity, population size, size structure, and reproductive output are impacted by the size of habitat patches on which they are resident.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

2001

Author dc:creator

• Robertson, Denice N.

Contributors dc:contributor

• Mark J. Butler IV
• Fred C. Dobbs
• Cynthia M. Jones

• Mating
• Panulirus guttatus
• Population dynamics
• Spotted spiny lobster
• Ecology and Evolutionary Biology
• Marine Biology
• Oceanography

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Identifier

9780493565859

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:biology_etds-1100