A study of freshwater invertebrate distribution and abundance from fieldwork by secondary school students in an Epping Forest pond

Abstract

Records of freshwater invertebrates from fieldwork undertaken by 14–18-year-old secondary school students over a two-year period have been collated to give an account of their varying distribution and abundance, and an Insight Into me community dynamics in tower Wake Valley Pond, Epping Forest. Student data have been processed to provide information on invertebrate habitat preferences and the abundance and biomass present in different trophic levels over time, using the concept of Eltonian pyramids. Throughout the study period, herbivores and detritlvores were usually the dominant trophic groups. However, during the summer months there were episodes when abundance and biomass became severely depressed, and large carnivores became dominant. These inversions of number and biomass pyramids reflected extreme variations in waterflea populations, which in turn resulted principally from seasonal variations In primary production by planktonic algae, affected by seasonal changes in temperature, insolation and nutrient status. It appears that waterfleas and a few other invertebrate taxa are responsible for transferring the majority of energy in this pond ecosystem, but that many other diverse taxa, each with different niches, subsist by transferring relatively small amounts of energy.

Keywords:

• Freshwater ecology
• Field studies