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Emily Lamb, Environmental Studies Sc.B. Candidate (Class of 2011)

20May10

Honors Thesis Proposal

Climatesroleinmediatingcompetitionbetweentwointertidalbarnacles,JehliuscirratusandNotochthamalusscabrosus

MotivationandContextSpecies distribution patterns on rocky shores are classically considered to be set by physical

stress at the upper limit and by competition and consumer pressure at the lower limit (Bertness2007). Temperature in particular plays an important role in the community structure, speciesinteractions and organism level processes throughout these systems (Harley 2008), and thus rockyintertidal communities are predicted to see myriad changes in the face of climate change(Helmuth et al. 2006). In order to understand how changes in climate (particularly temperature)will manifest themselves, it is important to understand the current role of physical stress in theseenvironments.

The role of physical stress in the rocky intertidal is often complex, affecting not only speciesdistributions but also their physiology (Helmuth and Hofmann 2001), survival (Gedan et al. inprep.) and potentially their interactions with other species (Broitman et al. 2009). Barnacledistributions on rocky shores, in particular, and the role physical stress plays in setting thoselimits has received much attention (e.g., Berger and Emlet 2007; Bertness 1989; Harley andHelmuth 2003; Wethey 1983, Gedan et al., in prep). Along the central Chilean coast, twobarnacle species -J ehlius cirratusandNotochthamalus scabrosus- coexist extensively (Shinenand Navarrete, in press).J ehliusnumerically dominates slightly higher in the barnacle zone whileNotochthamalusdominates slightly lower. However, the zonation is not a sharp break; on thecontrary the species distributions overlap up to 60-80% of the upper intertidal zone (Shinen andNavarrete, in press). Several potential mechanisms of coexistence are under investigation;however; patterns of recruitment and adult populations suggest that physical stress may bemediating competition between these species. Specifically,J ehliusrecruits more heavily thanNotochthamalus throughout the barnacle zone but onlyNotochthamalusrecruitment patternscorrelate to adult populations suggesting that the species distributions observed are due, in part,to some sort of post-settlement mortality (Shinen and Navarrete, in review).

Intriguingly, previous studies addressing the interaction between these two barnacles eachconducted at single locales of varying latitude along the coast of central Chile, arrived atconflicting conclusions. At the northernmost site Paine (1981) found not only that mixed-speciespatches tended towardsJ ehliusdominance over time but also thatJehliusovergrew adjacentNotochthalamus individuals 100% of the time. More recently at a southerly site, Lpez andGonzlez (2003) found that the presence ofNotochthamalus increases the mortality rate of

J ehliusand suggests thatNotochthamalus is therefore competitively inhibitingJ ehilus. Finally ina centrally located latitude, Shinen and Navarrete (in press) followed adult individuals of bothspecies in various crowding conditions (solitary, surrounded by conspecifics, surrounded byheterospecifics) and found that their growth rates were unaffected by inter- or intraspecific

interactions. Although none of these previous studies specifically addressed nor controlled forphysical stress, taken as a whole, they suggest that physical conditions that often vary widelyamong sites (ie temperature, sun exposure, desiccation stress) may change competitiveinteractions betweenJ ehliusandNotochthamalus. As climate change forces more species rangespoleward (Beerling 1993; Jeffree and Jeffree 1996), the interspecific interactions and patterns ofcoexistence betweenJ ehliusandNotochthamalusmay also be disrupted, making understandingthe role of physical conditions in their competitive interaction particularly important tounderstand in the face of climate change.

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ResearchQuestionMy research will directly address the role of climate in the competition/coexistence of

J ehliusandNotochthamaluson Chiles central coast. The specific question I will address is what effect does temperature stress have on the survival and growth rate ofJ ehliusandNotochthamalusat two different tide heights?

ApproachI will address this gap in our knowledge about the role of climate stress on the interaction

betweenJ ehliusandNotochthamaluson the central Chilean Coast through shading experimentsin collaboration with Drs. J enna Shinen and Sergio Navarette of ECIM (Estacin Costera deInvestigaciones Marineras) and Prof. Heather Leslie of Brown University. Each month, fromMarch 2010 through August 2010, I will monitor the growth rate, mortality and settlement ofbarnacles in response to varying physical factors such as temperature, emersion time anddesiccation rate in both shaded and unshaded plots (through photographs and field observations)as well as record air and water temperature using waterproof temperature loggers (Onset TidBitloggers). This experiment will be conducted at two sites with different physical conditions andrecruitment rates. From March through July 2010 I will be enrolled at Pontifica UniversidadCatlica, Valparaso and monitor the plots from there. In August 2010 I propose to return toECIM, where I have been living and working for the last six weeks (January-March 2010), tobegin to analyze my data. Dr. Shinen will continue monitoring the plots when I return to theUnited States in Fall 2010. I will continue to analyze data and begin to write up my resultsthrough the Fall of 2010, under the guidance of Prof. Leslie as well as my Chilean mentors.

AnticipatedResultsDue to the recruitment patterns mentioned above, along with the fact that adults of both

species coexist for such a large portion of the barnacle zone (Shinen and Navarrete, in press), Ihypothesize that the zonation patterns are determined through post-settlement mortality beforeindividuals become fully established adults. I also expect to seeNotochthamalus flourishinghigher in the barnacle zone under shaded plots than in unshaded plots, due to the alleviation ofthermal stress.

SignificanceDue to the large role played by physical conditions in rocky intertidal systems,

understanding the various ways in which they will be affected by the myriad changesaccompanying changes in air temperature associated with climate change is critical. This studywill fill a key gap in knowledge about thermal stress responses in a well-studied coastal marineecosystem(e.g., Castilla et al. 2005; Navarrete et al. 2005; Fernandez et al. 2006; Navarrete andManzur 2008; Wieters et al. 2008) and provide insight into the fundamental mechanism behindthe coexistence of these two ecologically important species. Barnacles may be particularlysensitive to temperature increases since they may already be living at the limit of their thermal

stress tolerance (Bertness 1989, Berger and Elmet 2007, Leslie et al., unpub. data). Thus barnaclespecies distribution patterns could potentially serve as an indicator of changing temperatureregimes in this and other coastal ecosystems.

I hope that this research result in a peer-reviewed publication in collaboration with mymentors. In addition, since this study will be conducted at marine labs in Las Cruces and Via delMar, Chile, it will foster international collaboration amongst international students, postdoctoralresearchers, and professors, therby creating an opportunity for future collaboration betweenBrown and Pontificia Universidad Catlica de Chile.

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TimelineFeb-Mar2010

Mar-Jul2010

Aug 2010 Fall 2010 Spring 2011

Experimental Setup XXXXExperimental Monitoring XXXXXX XXXXX XXXXXXX XXXXXData Analysis XXXXXX XXXXX

Writing XXXXXX XXXXXXXThesis Submission XXXXXXX

Preliminary BudgetShades and shade installation (shade cloth, plastic mesh, pvc pipe, cable ties, plastic clips, 80 screws andsettings, drill bit) ~$125

Travel to and from sites and overnight lodging at ECIM ~$20 per/trip X5 trips =$100August living expenses and lab fees ~$400Stipend for August ~$1000Unknown costs: Use of ECIM equipment (camera, drill, TidBit temperature loggers, IR temperature reader,light meter etc.) and help installing experiment

References

Beerling, D. J. 1993. The impact of temperature on the northern distribution-limits of the introduced speciesFallopia japonica and Impatiens glandulifera in northwest Europe. Journal of Biogeography20:45-53.

Berger MS and Emlet RB 2007. Heat-shock response of the upper intertidal barnacleBalanus glandula: Thermal stressand acclimation. Biological Bulletinvol 212 iss 3 pp 232-241.

Bertness, M. D. 1989. Intraspecific competition and facilitation in a northern acorn barnacle population. Ecology70:257-268.

Bertness M. 2007. Chapter 5: Rocky Shores. Atlantic Shorelines. Princeton University Press, Princeton, NJ .

Broitman BR, Szathmary PL, Mislan KAS, Blanchette CA and Helmuth B. 2009. Predator-prey interactions underclimate change: the importance of habitat vs body temperature. Oikosvol 118 pp 219-224.

Castilla JC, Uribe M, Bahamonde N, Clarke M, Desqueyrox-Faundez R, Kong I, Mayano H, Robaczylo N, SantelicesB, Valdovinos C and Zavala P. 2005. Down under the southeastern Pacific: marine non-indigenous species in Chile.Biological Invasionsvol 7 pp 213 232.

Fernandez M, Pappalardo P and Jeno K. 2006. The effects of temperature and oxygen availability on intracapsulardevelopment ofAcanthia monodon(Gastropoda: Muricidae). Revista Chilena de Historia Natural vol 79 pp 155-167.

Gedan, K. B., J . Bernhardt, M. D. Bertness, and H. M. Leslie. in prep. Substrate size mediates thermal stress in therocky intertidal. In prep. for Ecology.

Gilman SE, Wethey DS and Helmuth B 2006. Variation in the sensitivity of organismal body temperature to climatechange over local and geographic scales. Proceedings of the National Academy of Sciences (PNAS) vol 103 iss 25 pp9560-9565.

Harley CDG and Helmuth BST 2003. Local and regional-scale effects of wave exposure, thermal stress, and absoluteverses effective shore level on patterns of intertidal zonation. Limnology and Oceanographyvol 48 iss 4 pp 1498-1508.

Harley C et al. 2008. Tidal dynamics, topographic orientation and temperature mediated mass mortalities on rockyshores. Marine Ecology Progress Series. v 371 pp 37-46.

Helmuth BST. and Hofmann GE. 2001. Microhabitats, Thermal Heterogeneity, and Patterns of Physiological Stress inthe Rocky Intertidal Zone. Biological Bulletinvol 201 pp 374-384.

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Jeffree, C. E. and E. P. Jeffree. 1996. Redistribution of the potential geographical ranges of mistletoe andColorado beetle in Europe in response to the temperature component of climate change. Functional Ecology10:562-577.

Lpez DA and Gonzlez ML 2003. Density-dependent effects inJ ehlius cirratus(Darwin, 1854) (Cirripedia:Chthamalidae) under different growth conditions. Marine Ecologyvol 24 iss 4 pp 289-302.

Navarrete SA, Wieters EZ, Broitmn BR and Castilla JC. 2005. Scales of benthic-pelagic coupling and the intensity ofspecies interactions: From recruitment limitation to top down control. PNASvol 102 iss 50 pp 18046-18051.

Navarrete SA and Manzur T. 2008. Individual and population level responses of a keystone predator to geographicvariation in prey. Ecologyvol 89 iss 7 pp 2005-2018.

Paine RT 1981. Barnacle ecology: Is competition important?: The forgotten roles of disturbance and predation.Paleobiologyvol 7 iss 4 pp 553-560.

Shinen JS and Navarrete SA, in press. Coexistence and intertidal zonation of chthamalid barnacles along central Chile:Interference competition or a lottery for space?Journal of Experimental Marine Biology and Ecology.

Wethey DS 1983. Geographic limits and local zonation: the barnacles Semibalanus (Balanus)andChthamalusin NewEngland. Biological Bulletinvol 165 pp 330-341.

Wieters EA, Gaines SD, Navarrete SA, Blanchette CA and Menge BA. 2008. Scales of dispersal and the biogeographyof marine predator-prey interactions.The American Naturalistvol 171 iss 3 pp 405-417.