Citizen science initiatives document biodiversity baselines at an urban lake

Abstract

Changes to biodiversity from urbanization are occurring worldwide, and baseline data is vital to document the magnitude and direction of these alterations. We set out to document the biodiversity of an urban lake in Eastern Iowa that was devoid of baseline data prior to a renovation project that will convert the site into a major area for human recreation. Throughout the course of one year, we studied the biodiversity at Cedar Lake utilizing the citizen-science application iNaturalist coupled with semi-structured BioBlitz events, which we compared to previous opportunistic observations at the site. From a semi-structured approach to document biodiversity with citizen science, our analyses revealed more diverse community metrics over a shorter period compared to more than a decade of prior observations.

Keywords: Baseline data; Biodiversity; Community composition; Global change; Species richness; Urban biodiversity; Urban lake.

Figure 1. Map of study site and observations.

Map of study area at Cedar Lake, Linn County, Iowa. Comparison of Research Grade observations between time periods with pink dots representing prior work (2008–2021) and yellow dots our study (2021–2022). Colored lines are lake boundaries with blue representing the lake edge (0 m), green ≤10 m from lake edge, red ≤50 m from lake edge, and pink ≤100 m from lake edge. Observations recorded beyond 100 m from the lake’s shore were excluded from analysis. Image modified from Google Earth (Image Landsat/Copernicus).

Figure 2. Species accumulation curves.

Rarefaction species accumulation curves with extrapolation and 95% confidence intervals by group for Research Grade observations at Cedar Lake, Linn County, Iowa. Orange circle represents prior work (2008–2021) and blue triangle our study (2021–2022). Solid lines are observed and dashed lines are extrapolated values. Curves were generated with 1,000 bootstrap replicates using the R package iNEXT.

Figure 3. Rank curves for species between time periods.

Rank frequency of observation curves for Research Grade observations at Cedar Lake, Linn County, Iowa. Red line (Zipf) represents prior work (2008–2021) and orange line (Mandelbrot) our study (2021–2022) with the top three species indicated for both.

Figure 4. Before and after construction from satellite imagery.

Overhead satellite images of the study site at Cedar Lake, Linn County, Iowa, taken before (2020) and after (2022) major structural changes began in an effort to renovate the site for flood prevention and improvement of recreational services. Our surveys took place in 2021 before habitat alterations were underway, thus serving as a critical baseline for biodiversity at this site. Images modified from Google Earth: Top (Image Landsat/Copernicus); Bottom (Image©2023 Maxar Technologies).