Primary producers, including algae, cyanobac-teria, bryophytes, and vascular plants, are important basal resources in lotic food webs. As discussed in Chapter 6, macrophytes are subject to comparatively little grazing pressure before entering the detrital pool, and phytoplankton play a relatively minor role in most free-flowing rivers. Grazing on benthic algae by invertebrates, some fishes, and a few amphibian larvae is the most important pathway of herbivory in streams, and has received by far the most study. Benthic algae vary in their distribution, growth form, and nutritional value, and grazers differ in their means of scraping and browsing this food supply (Section 8.2.3). Thus, which algae are consumed reflects their vulnerability to particular grazers, and possibly aspects of preference as well. Grazers can have a number of impacts on algae, reducing their abundance, altering assemblage composition, and even stimulating algal growth and overall productivity through the removal of senescent cells and the recycling of nutrients (Feminella and Hawkins 1995, Steinman 1996).

Project Earth Conservation

Project Earth Conservation

Get All The Support And Guidance You Need To Be A Success At Helping Save The Earth. This Book Is One Of The Most Valuable Resources In The World When It Comes To How To Recycle to Create a Better Future for Our Children.

Get My Free Ebook

Post a comment