2010 Maine Water Conference
Wednesday, March 17, 2010
Augusta Civic Center, Augusta, Maine

SESSION H.
Biotic & Abiotic Influences on Water Quality
Chair: Ken Johnson, Husson University

Description: Nitrogen and Phosphorous are key nutrients that control tropic status and influence water quality.  In case studies and across the state, this session will explore top-down and bottom-up influences on nutrient sources and cycles, historical trends, and spatial surveys of lake and stream water quality.  Specific topics include food-web dynamics, indicators of trophic status, chemical-nutrient equilibria, and long-term temperature studies.

ABSTRACTS

• Stream algal model for predicting attainment of Maine water quality classes
  Thomas J. Danielson, Maine Dept. of Environmental Protection; Cynthia Loftin, UMaine Cooperative Fish & Wildlife Research Unit
  
  The Maine Department of Environmental Protection is responsible for monitoring aquatic life in the State’s rivers and streams and determining if they attain aquatic life criteria.  Maine’s water quality standards assigned one of four goals (AA, A, B, and C) to each stream and river segment in the state.  The Department currently relies on a statistical model using benthic macroinvertebrate data to predict the likelihood of a stream or river attaining its assigned class.  The purpose of this study was to develop a second model using benthic algal data to predict class attainment.  Adding a second taxonomic assemblage improves the ability to detect environmental degradation and diagnose stressors.  During 1999-2006, the Department collected 298 samples from 193 locations across the state.  Five professional biologists independently interpreted algal community data and variables with Maine’s narrative aquatic life criteria and the U.S. Environmental Protection Agency’s Biological Condition Gradient framework and assigned a class attainment (i.e., AA/A, B, C, or non-attainment).  The five biologists later convened and assigned consensus class attainment.  The model was developed to replicate professional judgment and was based on a combination of novel variables and variables from the literature that were empirically shown to respond to environmental disturbance.  The model correctly predicted class attainment in more than 90% of samples in both the training and validation data sets. 
  
  
• Monitoring Maine lake temperatures, short term variation and longer term trends
  Daniel E. Buckley, Professor of Biology; Julie Daly, Associate Professor of Geology, University of Maine Farmington
  
  For over twenty years the scientific community has expressed concerns about the impact of human activities on the global climate.  Current climate change models have mostly addressed terrestrial and marine environments with comparatively little attention being paid to freshwater habitats.  Data from researchers in 2007 indicated that Lake Superior’s epilimnetic water temperatures have risen by almost 2oC since the 1980s (Austin and Coleman, 2008).  Collaborating data in Maine from 1850-2000 show that ice-out on large lakes is now happening significantly earlier (Hodgkins et al. 2002).  At UMF two lake temperature monitoring  programs  have been conducted since 2007, one by partnering  with lake associations and municipal  water districts to either use their existing temperature data or to set out water temperature data loggers during the open water seasons.  The second program has been monitoring thermal regimes in high altitude ponds using this same technology.  These data loggers are recording water temperatures every fifteen or twenty minutes for the majority of the open water season in over 30 of Maine’s lakes and ponds.   In addition to providing a substantive data set for the long term monitoring of local lake temperatures, the technology is providing a far more nuanced picture of short term lake thermal dynamics.   Initial data analyses and longer term goals of these programs will be presented.
  
  
• Seasonal changes in phosphorus and iron pore-water profiles in the sediment of two shallow lakes: a diffusive equilibrum study
  Bjorn A. Lake, Ph D., Civil & Environmental Engineering; Aria Amirbahman, Professor Civil & Env. Engineering, University of Maine
  
  Phosphorus (P) and iron (Fe) pore-water concentration profiles were inferred temporally in 2009 using diffusive equilibrium polyacrylamide gel samplers in a mesotrophic and eutrophic lake in Maine, USA. The concentration profiles were modeled to determine benthic fluxes and zones of production/consumption in the sediment. In the zones of consumption, saturation indices for common P and Fe containing minerals were calculated using porewater data to determine possible consumption mechanisms via precipitation reactions. The results show that for both lakes, Fe and P exhibit similar patterns in the sediment. Early in the year, deeper sediments have zones of production which supply the upper sediment with P and Fe. By the time the oxycline reaches the sediment-water interface (SWI), a large reservoir of reducible P and Fe has accumulated. When the hypolimnion becomes anoxic, initially there is a large flux value of both Fe and P which steadily declines as the stratification period progresses due to the depletion of the solid phase and a lessening of the chemical gradient caused by hypolimnetic accumulation. Throughout the year, zones of Fe and P production also create chemical gradients that diffuse into the deeper sediments replenishing the solid phases at depth. Vivanite [Fe3(PO4)2] and hydroxyapatite [Ca5(PO4)3(OH)] are supersaturated in the zones of consumption at depth suggesting these mineral formations are possible sinks of Fe and P. The main difference between the P production zones of the two lakes are the size and the proximity to the SWI. Also, the eutrophic lake has more evidence of microbial uptake of sedimentary P and a higher degree of rapid mineralization later in the year at the SWI.
  
• Impacts of White Perch Introductions on Food Web Dynamics: Paleolimnological and Experimental Analysis of Zooplankton Grazing and Nutrient Cycling
  Kristin Ditzler (student), Jasmine Saros, Kevin Simon, Michael Kinneson; University of Maine
  
  Fish introduction to lakes may result in changes in zooplankton and algal communities via cascading interactions in food webs.  Current knowledge of the large-scale and long-term impacts of planktivorous fish introduction, through both size-selective predation and altered nutrient cycling, is limited for Maine lakes but is necessary for effective management of water quality.  Paleolimnological techniques were used to study long-term trends in lake plankton before and after known dates of white perch introduction.  Responses in the plankton community were counter to those expected from a top-down trophic cascade caused by size-selective predation by perch.  In order to explore the mechanistic links between fish introduction and lake ecosystem response, the paleolimnological analyses were paired with experimental studies to isolate the impacts to plankton communities through both predation and changes to nutrient cycling.  This analysis provides insight into the long-term development, past conditions, and mechanisms of biological response of lakes to fish introduction at the whole lake scale.