This summer I worked for Dr. Peter Siver as a research assistant in the Connecticut College Freshwater Ecology Lab. The focus of the lab research was the use of siliceous microscopic algae, such as chrysophytes and diatoms, as biological indicators of environmental change in freshwater ecosystems. For the past nine years, lakes along the Eastern Seaboard have been sampled by the Freshwater Ecology Lab and their sediment and water have been analyzed for chemical, physical, and biological variation due to acid deposition and changes in land use.
This summer, the lab group traveled to Newfoundland to sample approximately 32 lakes on the southeastern and central coast of the province. The areas sampled were locally known as the Avalonia region, the Irish Coast, and Terra Nova National Park. I found the sampling trip to be the most exhilarating part of the summer because this was my first trip to the province. The landscape of Central Newfoundland is a vibrant and lush forest-green countryside covered with native purple larkspur. When driving down the main highway to the sampling sites, I was always in awe of how pristine the land was. The landscape was a welcome change from suburban Connecticut.
The environment of each lake was thoroughly assessed through water, sediment, and periphyton collection. The duties for the sampling of each lake were shared and rotated at each sampling site. One of my primary responsibilities involved extracting sediment and periphyton from the tops of rocks and on the underside of aquatic vascular plants. Periphyton is a mix of algae and heterotrophic microorganisms that are bound together and live on top of a variety of substrates in freshwater and marine ecosystems. To the untrained eye, periphyton is simply considered slime, when it is in fact a tiny world brimming with life that gives insight into the health of an aquatic ecosystem. These samples were then prepared and analyzed later to determine the relative abundance of microscopic flora in the water body. I catalogued a variety of macrophytes to aid in understanding the local flora, and participated in taking cores of the sediment layers from the bottom of the lakes. The process for taking cores involved lowering a heavy instrument consisting of a plastic tube and a metal plunger from the canoe into the water. When the corer feels the bottom of the plastic tube hit the lake bottom, he or she releases a metal messenger that travels down the rope line and hits the top of the plunger, forcing it to cap the top of the tube. The water and sediment column (known as a core) is now suspended in the plastic tube, and is cut into 1 cm segments using an extruder. Each cm of sediment represents a block of years in the life of the lake. After the segments of sediment are processed and prepared on slides, I am able to examine the slides and quantify inferentially how the lake's environment has changed over time. Other responsibilities consisted of using the Hydrolab to test the water for dissolved oxygen, chlorophyll content, pH, and conductivity at different depths; and collecting water from the lake which would be used for further testing back at the lab.
Going out in the canoe was my favorite part of sampling, because it is always cooler in the middle of a lake than ashore on a hot summer day. I got the best view of the lake's profile from the canoe, because I could see where all the animal habitats, lake zones, and buildings on shore were. The lakes tested on this sampling trip included a variety of different types of freshwater lake environments. For some of the study sites, the watershed was the size of multiple football fields. For others, the watershed was the size of a small classroom. I learned a great deal about how land topography can dramatically change water movement on such a small area of land, and how slight changes in the surrounding environment can inversely affect the sanctity of a lake's water. The sampling trip also helped me meet an assortment of people in Newfoundland. The people I encountered were extremely kind, helpful, and fascinating people. Many people would come up to us inquiring about our research, and often would give us historical insight into the lake we were sampling. One man actually told us about logging patterns of the forest surrounding a lake in the Avalonia region that I am analyzing as part of my thesis.
Before and after the sampling trip, the rest of the summer consisted of collecting samples from Connecticut lakes for the Department of Environmental Protection. Starting last year and ending next summer, the study involves our lab compiling data from 60 lakes scattered across the state. Each year, 20 lakes are picked from the 60 by a random number generator. Before the Newfoundland trip, the lab collected spring lake data from the 20 lakes assigned this year. After the trip, we collected the summer lake data from the same 20 lakes. It was an extremely physically intensive summer, when most days we left at seven in the morning and did not return to lab until six in the evening. The sampling days were adventurous; the lab went out regardless of the weather. On one of the most beautiful days, it started to rain buckets in a complete downpour. Unwilling to go back, we took the core amidst the wind, lightning and thunder. When we had treacherous sampling days like that, it only strengthened our resolve and gave us a feeling of invincibility.
About one day a week we stayed in the lab and during that time we processed the water, periphyton, and sediment samples for both Newfoundland and Connecticut. I was responsible for digesting the periphyton and sediment for slide preparation. The periphyton and sediment were digested with acid so that all the organic material would be removed, with only the siliceous scales of chrysophytes and diatoms remaining. The samples were then prepared as slides so that different species of chrysophytes and diatoms could be counted. A portion of the sediment was also dried and ground up into a fine powder. The process of grinding involved all of the student workers sitting with a mortar and pestle for eight hours a day. The powder could then be tested to determine the age of the sediment, which would aid in inferring the age of the lake. The water was tested for a variety of measurements including chlorophyll content, cation content, pH, absorbance, and color. For example, pH shows the lake's level of acidity, chlorophyll shows the concentration of algae within the water body, and absorbance the amount of the light being absorbed into the water column. All of these measurements combined and calibrated give insight into a lake's properties and overall health.
For my thesis I will be using some of the data collected this summer to investigate how certain anthropogenic activities can have adverse effects on lake environments. The study will focus primarily on five different lakes along the same climatic gradient. The study includes one lake in Cape Cod, one in Maine, one in Nova Scotia, and one in Newfoundland. Each lake has been disturbed by a type of human interference, including acid rain, deforestation, road construction, and increased residential development. I hope to investigate how these factors have affected the lake's physiological, biological, and chemical properties using paleolimnological inference models of algal habitats. My work will include determining the chrysophyte species' distribution on slides of different depths of the sediment core. Due to the sensitivity of many species of chrysophytes to slight environmental change, I will be able to infer how a lake's chemical properties have changed over an extended period of time. When looking at a lake impacted negatively by humans, the inferential modeling will show what the lake's environment was like before and after the event. If the data show environmental change due to human interference, I hope to use historical data in conjunction with data on a lake's current environment to determine if it is capable of recovery. I hope that my research will be of service to the lab, emphasizing the importance of proper lake management to ensure the health and viability of all freshwater ecosystems.
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