The relative roles of dispersal and establishment for shaping whole-lake aquatic macrophyte richness, diversity, and community structure in hemiboreal lakes

ABSTRACT

Aquatic macrophyte diversity and structure play an important role in freshwater communities, yet little research on macrophytes has focused on native communities in the undisturbed hemiboreal lakes of North America. We used data collected from 15 inland lakes on Isle Royale National Park (Michigan, USA) to identify relationships among macrophyte metrics that describe dispersal and introduction potential (richness, diversity, community structure via growth form, and connectivity) and lake metrics that control establishment and growth potential. Results from partial least square regression analyses found that the most important and recurring predictors were those corresponding to establishment and growth. Alkalinity was the major contributor to the variation seen in richness, Shannon evenness, and Simpson inverse diversity metrics. Sediment phosphorus also contributed significantly to richness and diversity, but negatively. For growth form, half of the variation in submersed species related to alkalinity while almost half of variation in emergent species related to alkalinity and water color. Most of the variation in floating-leaved species was negatively related to alkalinity and water color. Our results suggest a high relative importance of establishment and growth metrics compared to introduction and dispersal metrics for understanding native macrophyte communities in North American hemiboreal lakes.

KEYWORDS:

• connectivity
• Isle Royale National Park
• lake morphometry
• partial least squares regression (PLSR)
• undisturbed lakes

Acknowledgements

This research was funded by the Institute of Water Research at Michigan State University (United States Geological Survey Project # 2012MI203B) and Michigan State University College of Agricultural and Natural Resources. We are especially grateful for the support of Lyman Briggs College and Jo Latimore of the Cooperative Lakes Monitoring Program at Michigan State University. Field data were collected by Kimberly Schoch, Sarah Schaffer, Charlotte Lee, Jennifer Hollen, Hannah Meikerjohn, Hayley Sisson, Kaitlin Clark, and Rachel Mistak. Special thanks to Joe Bump and Brenda Bergman at Michigan Technological University, the NPS staff at Isle Royale National Park for providing transportation and field support, Paul Bourdeau and Caren Scott for statistical guidance, and Dr. Kim Scribner and Dr. Garrett Crow for assistance with sampling design and plant identification.

ORCID

Angela A. De Palma-Dow http://orcid.org/0000-0002-6825-0028

Supplementary data

Supplemental data for this article can be accessed at https://doi.org/10.1080/20442041.2018.1522224