Citation:

Deeds, J., A. Amirbahman, K. Hugger, P. Kaufmann, L. Matthews, K. Merrell, AND S. Norton. Assessment Indices of Littoral Habitat Condition for Lakes in Maine and New England, United States. LAKE AND RESERVOIR MANAGEMENT. Taylor & Francis Group, London, Uk, 39(2):141-155, (2023). https://doi.org/10.1080/10402381.2023.2207490

Impact/Purpose:

This manuscript illustrates how the State of Maine leveraged the USEPA’s National Lakes Assessment (NLA) field and analytical methods to more effectively serve state agency needs for managing individual lakes within a smaller region than addressed by the NLA.   Lake shoreline and littoral habitat are critical for lake biota, but are adversely affected by residential shoreland development through the loss and reduced structural complexity of lakeshore vegetation. The NLA employs field and analytical methods for assessing littoral and shoreline condition in lakes at broad regional and national scales.  These methods are not necessarily optimum evaluating the condition of individual lakes; nor are they optimum for state or smaller region level assessments.  In this manuscript, Deeds and coauthors modified the NLA physical habitat field and analytical methods to more precisely evaluate the littoral and riparian habitat condition of individual lakes in Maine and the northeast US, where residential development is the primary stressor.  Their results show that efficacious single-lake littoral habitat assessments may be completed within the framework of the NLA Physical Habitat field and analytical methodology, but that confidence in assessment results, and therefore better-informed management decisions, can be improved with finer-scale observation data.

Description:

Littoral habitat is critical for lake biota, but it is adversely affected by residential shoreland development through the loss and reduced structural complexity of lakeshore vegetation. There currently exists no assessment methodology for evaluating littoral habitat condition of individual lakes in the northeast US. We addressed this assessment need by creating multi-metric indices of littoral habitat condition that focus on lakeshore residential development as the primary stressor. We did this by using habitat metrics derived primarily from National Lake Assessment (NLA) Physical Habitat (PHAB) survey field observations to create Linear Discriminant Analysis (LDA) models that assign lakeshore sites into littoral habitat condition categories. Lake PHAB survey data were used from New England NLA surveys as well as state-level surveys completed in Maine, New Hampshire, and Vermont. Prediction success rates in New England models ranged from 80.8% to 85.4%. The Maine LDA models, which used finer-scale survey methods, showed prediction success rates >90%. We used 95% bootstrapped confidence intervals to make assessment designations of natural (meeting reference quality), diminished (not meeting reference quality), or intermediate (existing between natural and diminished) littoral habitat condition for each lake. Our results show that efficacious single-lake littoral habitat assessments may be completed within the framework of NLA PHAB methodology, but that confidence in assessment results, and therefore better-informed management decisions, can be improved with finer-scale observation data.

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