Constructing a multi-metric model of ecological integrity for the lakes and ponds of Lassen Volcanic National Park, CA, USA

Background/Question/Methods

In the current study, we investigate the possibility and utility of developing an index of ecological integrity to assess and monitor ecological condition for mountain lakes and ponds in Lassen Volcanic National Park (northern California, USA). Assessing “status” and “trends” is a prominent mission of the Inventory and Monitoring Program of the National Park Service.  To assist the delivery of complex ecological data to non-science managers, multispecies and multimetric indicators of “ecological health” or condition are being increasingly recommended. By sampling multiple taxonomic groups (zooplankton, invertebrates, vertebrates), along with environmental parameters (water chemistry, physical habitat) we aimed to construct a usable multi-metric model of ecological condition in high elevation lakes of the Lassen highlands. We sampled 77 lakes in summer 2010 encompassing a range of disturbance (Low, Moderate, High). Disturbance was estimated based on landscape measures (e.g., trail density, proximity to roads) on both National Park and National Forest land. These lakes were sampled for physical habitat, water chemistry, physio-chemical profiles, zooplankton, littoral macroinvertebrates, and vertebrate assemblages using a peer-reviewed protocol for mountain lakes and ponds developed by the Klamath Inventory and Monitoring Program.

Results/Conclusions

We investigated the potential of three groups of indicators (Invertebrates, Zooplankton, and Water Chemistry) to differentiate disturbance categories using Multi-Dimensional Scaling (MDS) and Analysis of Similarity (ANOSIM). MDS showed distinct grouping of Low Impact lakes versus Moderate Impact Lakes, confirmed by ANOSIM (Global R = 0.318, p < 0.001). However, pairwise ANOSIM between Low Impact Lakes and High Impact Lakes was non-significant (R = 0.158, p = 0.08). Zooplankton displayed less distinct groupings in MDS, however pair-wise ANOSIM showed significant differences in Low Impact versus High Impact lakes (R = 0.087, p = 0.01). Water Chemistry results showed even less distinct groupings based on MDS, however High Impact lakes were significantly different from Low and Moderate Impact lakes using ANOSIM (R = 0.364, p = 0.006; R = 0.245, p = 0.044 respectively). These results demonstrate the potential for development of multi-metric models of ecological integrity for lakes, but the lack of distinct pairwise differences for some parameters (e.g., no distinction in High impact vs. Low impact invertebrate assemblages) in all groups illustrate the difficulties in constructing multi-metric models in protected areas, where disturbance gradients are more subtle and the protected area may be a unique feature on the landscape.