My lab studies invertebrate physiology and symbiotic relationships that can ultimately have ecosystem-wide impacts. Our research utilizes physiological and molecular techniques to identify ecological patterns associated with marine invertebrates and algae. Current projects focus on three main themes:

• marine invertebrate physiology and ecology during environmental perturbation,
• carbon and nutrient transfer in marine organisms, and
• diversity and function of microbial symbionts.

Invertebrate Ecology and Physiology During Environmental Perturbation

I am an integrative biologist that studies nearshore ecology and ecological physiology. I strive to push forward our basic understanding of marine ecology, evolution, and symbioses between invertebrates and their microbial partners. I have focused on teasing apart mechanisms that allow marine organisms to endure environmental perturbation and potentially drive acclimatization and adaptation to global climate change. To investigate organismal traits that result in impaired physiology and symbiotic disequilibrium, I have conducted field experiments and laboratory manipulations that combine ecological observations with molecular and physiological methods on marine invertebrates from Florida, Bahamas, Belize, Mexico, Curaçao, Panama, Virgin Islands, Philippines, Australia, and Palau.

Stable Isotope Analysis

When combined with physiological studies, stable isotopes are valuable to investigate potential physiological implications of niche partitioning and environmental perturbation. Differences in δ¹³C values between coral tissue and algal symbionts are broadly diagnostic of the relative amounts of photosynthesis and heterotrophy contributing to the carbon pool in corals. I have carefully developed experimental protocols using ¹³C enriched seawater to investigate inorganic carbon uptake and biological transfer of organic carbon to three biological compartments of reef-building corals (Symbiodinium, host tissue, and CaCO₃ deposition).

Nutrient enrichment (caused by sewage pollution) is contributing to the collapse coral reef ecosystems and has been linked to algal blooms and coral disease. Stable N isotope ratios (δ¹⁵N) have been successfully used in ecosystem studies to monitor anthropogenic nitrogen sources. To date, there is little regulation of sewage generated by tourists; therefore, resorts typically use underground injection into the coastal aquifer to dispose of wastewater. We feel that this additional stressor may pose alarming consequences for coral reef ecosystems that are already critically threatened by numerous environmental stressors (i.e., warm-water bleaching, coral diseases, removal of grazers, and ocean acidification).

Diversity of Microbial Symbionts Associated with Invertebrates

Symbiodinium spp. are highly diverse and can occur in symbiosis with mollusks, sponges, flatworms, protists, some ciliates, and cnidarians (including reef-building corals). Understanding the ecology and evolution of Symbiodinium diversity is important for predicting corals’ environmental susceptibility to perturbation.

Corals metabolize simple sugars that are supplied by Symbiodinium and are converted into complex carbohydrates, lipids, and released as exogenous mucus. This mucus creates a “carbon-rich” layer between the coral and the surrounding water and is colonized by hundreds of millions of microbes per square centimeter. Research investigating microbial communities of the coral mucus layer have shown a species-specific nature of coral-microbial assemblages. Furthermore, disturbance (natural or experimental) of the mucus-associated microbiota has been shown to result in coral mortality. Coral lack an adaptive immune system, and mucus-associated microbiota play an important role in coral immunity and disease resistance. I am interested in connecting links between physiology, ecology, and environmental perturbation that influences microbial associations at different functional levels.

• Seminar in Ecology (BY 499/692/792): Symbiosis and Symbiotic Interactions

• Kemp DW, Colella MA, Ruzicka RR, Bartlett LA, Porter JW, Fitt WK. "Life after cold death: Reef coral and coral reef responses to the 2010 cold water anomaly in the Florida Keys." Ecosphere 7 (No. 6, 2016): e013373.
• Russell BJ, Dierssen HM, LaJeunesse TC, Hoadley KD, Warner ME, Kemp DW, Bateman TG. "Spectral reflectance of Palauan reef-building coral with different symbionts in response to elevated temperature." Remote Sensing 8 (3, 2016):164, doi:10.3390/rs8030164.
• Sutherland KP, Berry B, Park A, Kemp DW, Kemp KM, Lipp EK, Porter JP. "Coral disease etiologies as moving targets: a 20-year case study of white pox disease affecting Acropora palmata in the Florida Keys, 1994-2014," Phil Trans Roy Soc B (2016): 371, 20150205.
• Kemp DW, Rivers AR, Kemp KM, Porter JW, Lipp EK, Wares JP. "Spatial homogeneity of bacterial communities associated with the surface mucus layer of the reef-building coral Acropora palmata." PLOS One 10 (no. 12, 2015): e0143790.
• Joyner JL, Sutherland KP, Kemp DW, Berry B, Griffin A, Porter J, Broome MH, Noren H, Lipp E. "Systematic analysis of white pox disease in Acropora palmata of the Florida Keys and the role of Serratia marcescens." Applied and Environmental Microbiology. doi:10.1128/AEM.00116-15.
• Kemp DW, Thornhill DT, Rotjan RD, Iglesias-Prieto R, Fitt WK, Schmidt GW. "Spatially distinct and regionally endemic patterns of symbiotic associations in a threatened Caribbean reef-building coral Orbicella faveolata." Coral Reefs 34 (2015):535-47.
• Kemp DW, Hernandez-Pech X, Iglesias-Prieto R, Fitt WK, Schmidt GW. "Community dynamics and physiology of Symbiodinium before during and after a bleaching event." Limnology and Oceanography 59 (2014):788-97. Featured in: Science Daily, NSF, Phys Org, Red Orbit, e! Science News.
• Kirk NL, Thornhill DJ, Kemp DW, Fitt WK, Santos SR. "Persistent associations between apicomplexan symbionts and Caribbean reef corals." Coral Reefs 32 ((2013):847-58.
• Thornhill DJ, Chilcoat GC, Iglesias-Prieto R, Kemp DW, LaJeunesse TC, Reynolds McCabe J, Rotjan RD, Schmidt GW, Shannon T, Todd BD, Warner ME, Fitt WK. "A connection between colony biomass and death in Caribbean reef-building corals." PLOS One 6 (2011):e29535.