Studing the Influences Of Fish Management & Climate Through Analysis Of Data and Lake Modeling

Castle Lake

Aquatic ecologists have long been interested in understanding the drivers of ecosystem production (i.e algae, fisheries, physical processes etc.). In 2007 UNR initiated a collaboration with the UC Davis to co-manage the Castle Lake Environmental Research and Education Program. The primary objective for this collaboration was to investigate reciprocal carbon exchanges and their role in supporting lake, and specifically fisheries productivity through

  1. expanding the existing lake pelagic monitoring program to capture carbon exchange (primarily invertebrates) between aquatic and terrestrial habitats and
  2. creating an empirical model of the food web that would leverage the Castle Lake Long-term (>53 year) dataset to investigate productivity drivers.

The first four years of this collaborative effort produced preliminary results suggesting that climate and stocked trout populations act as key drivers of annual primary productivity in Castle Lake. Annual stocking practices also appear to be correlated with decreased density and altered species composition of emerging aquatic invertebrates subsidizing the riparian and terrestrial food webs. 

Additionally, and perhaps most significantly, the initial phase of the study revealed that this relatively pristine mountain lake environment has undergone a dramatic “regime shift” in certain ecological attributes including primary production and clarity, while other more stable climate attributes including ice out date and spring snow water content, remain unchanged or only slight increasing over time.  These patterns have occurred concomitant with, an increasing trend in air and surface water temperatures during the summer season, with a significant departure in summer night time air temperature in the last decade, as well as increased stocking and manipulation of fisheries.

This project continues the collaboration; building on the research and modeling work accomplished to date, and develop information for future proposals and continue the program. In this phase, we will analyze the relative influence of biotic and abiotic drivers of ecosystem productivity through the application of a structural equation model. The analysis will be guided by a conceptual model and monitoring program developed during the initial phase of this project and focused on the components of climate and fisheries, necessary to tease apart there relative influences on lake production.