Current Research Projects
My students work on diverse systems and you should refer to their pages for details. Below, I summarize some of my major projects.
Settlement shadows. Since our earlier work on artificial reefs (Osenberg et al. 2002), we've conducted an experiment to evaluate the Field of Dreams Hypothesis vs. the Propagule Redirection Hypothesis (Stier and Osenberg 2010): adding or restoring habitat can alter the production of habitat-dependent organisms in two contrasting ways: (1) by enhancing input of new colonists to the new sites (the Field-of-Dreams Hypothesis); and (2) by drawing colonists away from existing sites (the Propagule Redirection Hypothesis). The latter does not add new colonists to the site, but because it redistributes them, it can increase regional density by reducing the deleterious effects of density. Our previous research showed that local reefs without neighboring reefs received two to four times more settlers than reefs with adjacent habitat, demonstrating that increased habitat redirected larval fish. At the scale of the entire reef array, total colonization increased only 1.3-fold despite a 6-fold increase in reef area (and a 2.75-fold increase in adjusted habitat availability). Thus, propagules were both increased and redirected, a result intermediate to the Field-of-Dreams and Propagule Redirection Hypotheses. We also used a recruitment model to show that the primary effect of new habitat was to ameliorate competition at existing sites rather than increase colonization at the new sites. Our new work (led by Elizabeth Hamman, and also involving Adrian Stier and Scott McKinley) has focused on developing dynamics models that: 1) incorporate long-term, multi-cohort dynamics; 2) examine the effects of spatial patterns of habitat on the spatial patterns of colonists; and 3) the feedbacks between the colonists and the habitat (e.g., to incorporate positive effects of coral occupants on coral growth).
Reef Fish Ecology. Much of my work focuses on recruitment processes, density-dependence and size-structure in reef fishes. A portion of our work synthesized existing studies using meta-analysis and have extended mathematical models of recruitment processes in fishes. This work was sponsored, in part, by our project on marine ornamentals (see below), by the National Center for Ecological Analysis and Synthesis (in Santa Barbara, California), and by NSF. We also investigate the efficacy of marine reserves and alternative management practices (both by using mathematical and statistical models; and by conducting empirical studies). A portion of this work was based in Moorea, French Polynesia. The NSF work was built around our work on cryptic density dependence (sensu Wilson and Osenberg 2002, Shima and Osenberg 2003, 2015).
Vermetid - Coral - Fish Interactions. During our work on reef fish in Moorea, we discovered that sessile, vermetid gastropods (see picture to the right) can have large deleterious effects on coral growth and survival. Our ongoing work is exploring the mechanisms and consequences of these effects, and is a major focus of my ongoing research in the Indo-Pacific. This work is collaborative with Jeff Shima (Victoria University of Wellington, New Zealand) and Tom Frazer (UF) and it also involves many of my graduate students. During this project, we discovered muricid snails that consume vermetids and then lay eggs in the empty tubes (Brown et al. 2014) and we've also just recently (2015) witnessed a mass mortality of Dendropoma maximum -- whose populations have been destroyed in Moorea (with two-week mortality rates of >95%).
Soil C dynamics. Working with a diversity of colleagues (led by Bruce Hungate at NAU, and joined by Kees-Jan van Groenigen, Natasja van Gestel, Jeff Dukes, Yiqi Luo, and Kiona Ogle), we're using meta-analysis to understand soil C dynamics under climate change. My involvement is primarily through my expertise in meta-analysis (and not biogeochemistry!), and dates back to early discussions with Bruce at NAU, our meta-meta-analysis paper (Hungate et al. 2009), and the meta-analyses we did that were led by Kees-Jan (2011 and 2014).
Marine Ornamentals. Our project was designed to quantify the effect of density-dependence in reef fishes, estimate migration rates among, and settlement to, different habitats, explore relationships between benthic habitat characteristics and reef fish abundance, elaborate upon statistical aspects of the BACIPS assessment design, and model fish population dynamics. Our work helped elaborate upon the attraction-production hypothesis, and was designed to improve information that guides the management of the marine ornamental fishery (i.e., fishes harvested in the marine aquarium trade). Fieldwork was located in the Florida Keys, and the project supported a post-doc and a graduate student. PI's: Craig Osenberg, Colette St. Mary, Ben Bolker; Post-doc: Laurent Vigliola.
Restoration ecology of macrophytes in freshwater springs. Our two-year research project (now complete) was designed to understand the ecological factors influencing the dynamics and regeneration of Vallisneria in freshwater springs. Results were intended to guide restoration efforts being conducted by the Southwest Florida Water Management District. Fieldwork was conducted in Kings Bay in the upper Crystal River; lab work was conducted at the University of Florida. Field studies used experimental and observation approaches to quantify effects of herbivory demographic parameters for use in a stage-structured population dynamics model. The project supported a post-doc, a tech, and a graduate student. PI's: Tom Frazer, Craig Osenberg; Post-doc: Jennifer Hauxwell.
Phenotypic plasticity in sunfishes. Much of my past work has focused on stage-structured interactions among sunfishes and has also explored causes and implications of variation in their feeding morphology. Several of my students also worked on phenotypic plasticity, but in other aquatic systems (e.g., tadpoles). My older work on sunfish (collaborative with Peter Wainwright, Gary Mittelbach, and Casey Huckins) was designed to engineer different phenotypes (by exploiting phenotypic plasticity in jaw morphology), develop and test biomechanical models of molluscivory, to compare patterns of diet and morphology within the sunfish clade, and explore the implications of these findings to the evolution of molluscivory and phenotypic plasticity and the ecological significance with respect to predator-prey and competitive interactions. I have not worked in this area for quite a while, but I am very keen to attract a graduate student who would be interested in working in this or related areas.