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Publication Date

5-2024

Many studies have documented the detrimental effects of urbanization on aquatic ecosystems. What is less known is how “super urban” centers—areas with unusually high human population densities and immense infrastructures—impact biodiversity. Specifically, freshwater streams and rivers that are situated in highly urbanized metropolitan areas might be more susceptible to anthropogenic disturbance. Here, we evaluated the impacts of land use and human population density on benthic macroinvertebrate diversity along the Bronx River, a freshwater river situated in one of the largest urban centers in the world: the New York metropolitan area. We addressed the following research question: How does (1) high intensity development, (2) distance to the Bronx River Parkway, and (3) human population density impact benthic macroinvertebrate diversity along the Bronx River? To answer this question, we sampled benthic macroinvertebrates from 18 study sites, and calculated five measures of benthic macroinvertebrate diversity: (1) family richness, (2) Ephemeroptera-Plecoptera-Trichoptera (EPT) family richness, (3) Simpson’s diversity index, (4) invasive species abundance, and (5) family dominance. Our study yielded three main results. First, benthic macroinvertebrate diversity was extremely low. Across study sites, family richness ranged from two to seven and EPT family richness ranged from zero to one. Indeed, only four of 18 sites harbored pollution-sensitive mayflies (Ephemeroptera) or caddisflies (Trichoptera), and zero sites supported stoneflies (Plecoptera). Second, two measures of land use, high intensity development (80 to 100% impervious surface cover) and distance to a major highway (Bronx River Parkway) were associated with reduced biodiversity. Specifically, high intensity development was negatively associated with family richness and Simpson’s diversity, and positively associated with invasive species abundance. Study sites located closer to the Bronx River Parkway harbored more invasive species than study sites located further away. One invasive species, the Asian clam (Corbicula fluminea), was the second most dominant taxon on the Bronx River. Finally, we found that high human population density was negatively associated with family richness and positively associated with invasive species abundance. Our results suggest that “super urban” centers are especially vulnerable to anthropogenic pressures and that large urban areas warrant special attention for mitigating the decline of benthic macroinvertebrates.

DOI

10.15365/cate.2024.170105

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