Heather McCracken

M.Sc Candidate, Canadian Rivers Institute, Biology Department
Hometown: Fredericton, N.B. Canada

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Contact information

Room  232 Loring Bailey Hall
10 Bailey Drive,
Fredericton, New Brunswick
Email Heather

Education

B.Sc. Major in Biology, University of New Brunswick, Fredericton, N.B.

Awards and Scholarships

Province of New Brunswick, Environmental Trust Fund Grant for preserving existing biodiversity. Proposal title: Measuring ecological processes and biodiversity in New Brunswick Headwater Lakes. 2009-2010.

Province of New Brunswick, Environmental Trust Fund Grant for preserving existing biodiversity. Proposal title: Measuring ecological processes and biodiversity in New Brunswick Headwater Lakes. 2008-2009.

NSERC award for best paper, presented at APICS – Environmental Studies conference. March 2009.

Research

Supervisor: Dr. Rick Cunjak
Start date: September, 2007.

Title: Measuring lacustrine nutrient influence on composition and function in a stream community.

Headwater lakes are common characteristics of river systems in the province of New Brunswick, especially within the Miramichi River basin. The role of lakes and their effects on downstream communities has been relatively unstudied. By utilizing stable isotope analysis (SIA), our research aims to determine how a headwater lake may contribute energy (in the form of carbon and nitrogen) to the functional composition of a downstream riverine community. SIA is a proven biogeochemical tool used to determine major pathways within a food web.

During the spring and summer of 2008, samples from various trophic levels (i.e. 1° producers, 1° consumers etc.) were collected from 4 sites within Catamaran Lake, and from 3 sites (at 0.1km, 0.2km and 0.5km) within the outflow stream Catamaran Brook. Data will then analysed using a one isotope, two-source mixing model. It is predicted that the proximal downstream communities rely more so on nutrients derived from the headwater lake rather from the riparian borders of the brook that influence the distal sites.

Studies in 2009 will be devoted to exploring other lakes in the Miramichi River drainage. This may allow us to determine any commonalities in food web structures of similar lakes within this drainage.

Overall, the goal of this two year graduate research project is to identify and measure the sources of energy (specifically, Carbon and Nitrogen) that maintain the food web structure and productivity in headwater lakes. Specifically, our objectives are:

1) Determine the relative contribution of riparian (terrestrial) vegetation vs. aquatic primary producers (plankton, macrophytes) in sustaining the lake’s food web and energy flow to the top fish predator (e.g. brook trout; landlocked salmon).

2) Identify ‘keystone’ species and critical habitats that are disproportionately important in maintaining biodiversity ecological stability in the lake. Such information has important management implications.

3) Measure the influence of lake size (i.e. area and depth) and productivity on riverine food webs.

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Presentations

McCracken, H, and R Cunjak. 2009. Measuring lacustrine influence on composition and function in a stream community (oral presentation). Atlantic Provinces Council on the Sciences, Environmental Studies Conference, Fredericton, New Brunswick, Canada.