Undergraduate Interns

For prospective undergraduate interns:

The Donahue Lab has hosted many undergraduate interns (see project descriptions below).  Some students have worked in the lab as volunteers but others have acquired funding.  We have hosted UH undergraduates supported by the Undergraduate Research Opportunities Program, Native Hawaiians and Pacific Islanders supported by the Undergraduate Research and Mentoring in the Biological Sciences program, UH math-biology students through the UH Math-Biology Program, and UH Biology and Marine Biology students for 499 research  credits.  Students working at HIMB may qualify for a HIMB-specific scholarships that are offered every year; UH GES students may also qualify for specific scholarships.  For general information on finding an internship at HIMB, look here.

at Hawai’i Institute of Marine Biology

Nicholas Griffith (UH – Marine Bio) is an undergraduate Marine Biology major at UH Mānoa.  Having participated in the NSF-funded UH Math-Biology program, he continued working in the Donahue lab under graduate student Nyssa Silbiger.  Nick collected coral samples along a known pH gradient in Kāne’ohe Bay to determine the relationship between coral density and pCO2.  Increases in pCO2, a consequence of burning fossil fuels, can have serious implications for reef-building  corals.  In this study, Nick investigated the response of corals to natural  pH variation in coastal waters.  His results indicated that variability in  pH has a greater impact on coral  skeletal density than mean values.

Kelsie DiPerna (UH – Biology) worked in the lab for the duration of 2011.  Funded by the university’s Undergraduate Research Opportunities Program, she worked with graduate student Nyssa Silbiger on studying the composition of cryptofaunal communities in dead Porites compressa along a depth gradient just off Coconut Island.     She presented her results at the UH Fall Forum for Undergraduate Research, where she won best natural sciences poster.   Her poster describing the  results of her study  is here.

Lisa Hinano Rey (UH – Bio) joined the Donahue lab for Summer 2011 supported by the UH-URM program.  Lisa worked closely with graduate student Megsie Siple investigating the infaunal community of the He’eia Fishpond, and its response to mangrove removal.  Paepae O’ Heiea, caretakers of the fishpond, have been removing invasive mangrove from the rock wall of the pond (the photo to the left was taken several years ago, before the mangrove removal).  Lisa’s study sampled infauna along a chronosequence of mangrove removal from 1-5 years ago.  Overall, she found increasing infaunal density at older removal sites.

Nick Griffith (UH – Bio), Kyle Dahlin (UH – Math), and Heather Stever (UH – Bio) all participated in the NSF-funded Undergraduate Mathematics and Biology program at the University of Hawaii.  Corals have complex life-histories including sexual and asexual reproduction, fission and fusion of colonies, and a lack of discrete stage structure that makes demographic modeling a particular challenge.  Previous studies of coral population dynamics have used matrix models for coral population dynamics; however, this approach is limited by necessity of imposing arbitrary size classes and parameter estimation requirements that increase multiplicatively with the number of size classes.

Luke Wakeen, Nick Griffith, Kyle Dahlin, Heather Stever

In contrast, integral projection models (IPMs) use biologically meaningful, continuous functions for growth, survivorship, and fecundity as a function of size (Easterling et al 2000, Ellner & Rees 2006a), which can be fit from data using modern mixed-model approaches in a likelihood or Bayesian framework (Rees & Ellner 2009).  Using photoquadrats from 30 sites around the Main Hawaiian Islands over ten years, we are developing IPMs for the dominant coral species in the MHI.  Photoquadats are permanently marked, allowing sites to be relocated each year so that the fates of individual coral colonies can be tracked through time.  Nick and Kyle started on the project in Fall 2010 and presented a poster at the UH Honors Program Spring Symposium.  We were lucky to have Heather join the project for the Summer of 2011!   Luke Wakeen (St John’s College) joined the lab for Summer 2011 to work on 3D reconstructions of coral communities.

Griffith N, K Dahlin. 2011.  Tracking Coral through Time: the mathematics of coral life histories. Poster presented at UH Honors Spring Symposium, Manoa, Hawaii.

at Humboldt State University – Department of Biological Sciences

Kyle Derr (HSU Bio ‘08),  Johnny Kell (HSU Bio ‘07), Andrew Weltz (HSU Bio ‘08):  Most benthic invertebrates have a planktonic larval phase, which must be retained near shore in order to settle to benthic adult habitat. Seasonal variation in near shore oceanographic phenomena may provide an important key to understanding the mechanisms influencing retention and onshore transport of invertebrate larvae. In this study, we used three levels of sampling intensity and two levels of spatial resolution to investigate the influence of seasonal upwelling on the settlement of post-larvae in Trinidad Bay (Humboldt County, California), a small, south facing inlet formed by Trinidad Head.  At our primary site, we sampled weekly settlement from April 2006 to August 2007 and sampled intensively (every other day) for the month of June 2007.  During the upwelling season of 2007 (June and July), we performed twice-weekly sampling at near shore sites on the north and south of Trinidad Head (two sites each).  At each site, we tracked settlement of crabs (Cancridae, Grapsidae, Majidae, hermit crabs, and Porcellanidae), barnacles (Chthamalus spp. and Balanus spp.), bivalves, urchins, snails, and polychaetes.  Derr KP, JR Kell, and MJ Donahue.  2007.  Seasonal patterns of larval settlement at Trinidad Head: implications for retention and transport. Poster presented at Western Society of Naturalists, Ventura, California.

Trevor Goodman (HSU Bio ’07; now a Ship Tech on the R/V Kilo Moana) and Narineh Nazarian (HSU Bio ’08; now Asst DSO at U Hawaii) were part of a team that surveyed the California coast north of Cape Mendocino.  Despite increased monitoring of subtidal communities throughout California, this region remained understudied because there are few coastal access points, low visibility due to high sedimentation, and challenging ocean conditions for most of the year.  Trevor presented the results of these initial surveys at the Western Society of Naturalists meeting in 2007.  Goodman T and MJ Donahue. 2007.   Kelp forest communities north of Cape Mendocino: initial survey in Humboldt and Del Norte counties.   Poster presented at The Western Society of Naturalists, Ventura, California.

at Shoals Marine Laboratory

Meg Eastwood (left), Amy Fowler (right)

Meg Eastwood (2004 SML-REU; current: graduate student at UT School of Information) and Amy Fowler (2004 SML-REU; current: postdoc in marine invasive species at SERC).  Studying historic invasions can provide insight into the ongoing invasions that threaten global biodiversity. In this study, we reconsidered the impacts of two dominant invaders, Littorina littorea and Carcinus maenas, on the rocky intertidal community of the Gulf of Maine. Past research using invader-removal experiments demonstrated strong top-down effects of L. littorea on algal community structure; however, such removal experiments may overlook the long-term effects of niche shifts and local extinctions caused by invasive species. We considered how a niche-shift in the native littorine, Littorina saxatilis, may change the interpretation of L. littorea impacts. Using a factorial experiment crossing predator presence/absence with L. littorea presence/absence, we found that L. saxatilis is able to exert top-down control on ephemeral algae similar to that exerted by L. littorea and that both competition by L. littorea and predation by C. maenas have strong, negative impacts on L. saxatilis.   Eastwood, ME, MJ Donahue, and AE Fowler.  2007.  Reconstructing effects of past biological invasions: invasive predators and competitors and niche shifts in the New England intertidal community. Biological Invasions 9: 297-307

Cory Krediet (2005 SML-REU, current: grad student at U Florida).  Intertidal and shallow subtidal ecosystems experience steep environmental gradients over short distances.  Individual foraging rate, predation risk, and physiologic stress vary along these gradients, resulting in growth-mortality tradeoffs with depth.  While sessile organisms may adapt to local conditions via phenotypic plasticity, mobile organisms can move across the landscape in response to these tradeoffs.  Cancer borealis migrate seasonally with depth and are common in the shallow subtidal during  summer in the Gulf of Maine.  borealis migrate are common in the shallow subtidal during  summer in the Gulf of Maine.  C. borealis are the favored prey of the Herring Gull and the Great Black-backed Gull, which consume 25% – 50% of available (those at depths <1 m MLLW) C. borealis biomass during each daytime low tide.  We investigated three possible explanations for the presence of C. borealis in the risky gull-predation zone.  First, we tested whether predation risk in the gull-predation zone was matched at deeper depths by subtidal predators; we found predation risk decreases with depth.  Second, we tested whether water temperatures were warmer in the gull-predation zone and whether these warmer temperatures resulted in increased growth rates.  We found that, while waters were warmer in the gull-predation zone, crabs grew at similar rates above and below the thermocline when fed similar diets.  Finally, we tested for differences in food availability with depth and whether these differences influenced C. borealis growth rates.  Our results suggest that increased food availability rather than increased temperature is the primary benefit of foraging at shallower depths.  Krediet CJ and MJ Donahue. 2009. Growth-mortality trade-offs along a depth gradient in Cancer borealis. Journal of Experimental Marine Biology & Ecology. 373: 133-139.

Carlos Santamaria, Kestrel Perez, Allison Nichols, Paloma League-Pike, and Cory Krediet.  With the vision of the amazing Myra Shulman, SML-REUs from 2004, 2005, and 2006 contributed to a paper comparing the distribution, abundance, and behavior of the three crab species most abundant the nearshore waters of the Gulf of Maine, including two native Cancer crabs and the introduced Carcinus maenas:  Donahue MJ, AM Nichols, CA Santamaria, PE League-Pike, CJ Krediet, KO Perez, and MJ Shulman. 2009.  Predation risk, prey abundance, and the vertical distribution of three brachyuran crabs on Gulf of Maine shores.  Journal of Crustacean Biology. 29(4): 523-531.