Food Web Dynamics: How Urbanization of Riparian Systems Affects Prey Availability for Tetragnatha Spiders in Aquatic and Terrestrial Systems

Abstract

As the world becomes more urbanized, natural processes are changed. One such example is the alteration of food web dynamics through the introduction of pharmaceuticals and personal care products (PPCPs) into ecosystems. When riparian spiders, especially those of the genus Tetragnatha, consume emerging aquatic insects, PPCPs move into terrestrial systems. The purpose of this study is to determine effects of urbanization on body morphology and prey availability to tetragnathid spiders in different sites along the Gwynns Falls watershed near Baltimore, Maryland. To observe the effect of urbanization on prey availability, spiders and insects were collected along the Gwynns Falls watershed in sites ranging from urban to rural. The data suggest that there is more prey available to spiders in urban riparian systems than in rural riparian systems, and that the prey available in urban riparian systems is a higher proportion of aquatic species than terrestrial species. This is supported by the observation that the spiders in urban areas were significantly longer from cephalothorax to abdomen. Because the spiders are almost significantly larger in mass, the data implies that the prey is more available and nutritious in urban areas and therefore any contamination that exists is more accumulated in urban environments.