Screen reader users, click the load entire article button to bypass quantitative value gray carlisle pdf loaded article content. Please note that Internet Explorer version 8.
Click the View full text link to bypass dynamically loaded article content. This chapter describes the concepts and methods associated with secondary production primarily as it applies to freshwater invertebrates in stream ecosystems. Production is usually measured with either cohort or noncohort methods for which procedures and examples are provided. Cohort methods are based on sampling a synchronously developing population through time.
Noncohort methods use the same sampling procedure, but require an independent estimate of development time or biomass growth rate. J, C, or other elements. Production can be used to address a variety of population, community, and ecosystem questions, one of which is in the construction of quantitative food webs. The procedure for building two types of food webs is illustrated with hypothetical data, and two published webs are described. This article has not been cited. PTI is an indicator of potential toxicity of pesticide mixtures to aquatic life. The PTI was updated and expanded to include 440 pesticides and 52 degradates.
A new type of PTI provides a more sensitive indicator of potential toxicity. From published field data, daphnid mortality occurred above PTI values of 0. Pesticide mixtures are common in streams with agricultural or urban influence in the watershed. The PTI is determined separately for fish, cladocerans, and benthic invertebrates. This study expands the number of pesticides and degradates included in previous editions of the PTI from 124 to 492 pesticides and degradates, and includes two types of PTI for use in different applications, depending on study objectives.