ABSTRACT
This chapter discusses the use of mesocosm studies for causal assessment. Mesocosm studies combine some of the natural conditions and interactions captured in field studies with some of the controls afforded by laboratory experimental systems. Mesocosm studies can be used to tackle an extensive range of topics potentially relevant to causal assessments. They distinguish the contribution of different stressors under simulated site conditions and can be used to develop stressor–response relationships that can be compared to observations from the site. Investigators have used various lake and pond (i.e., lentic) mesocosm systems to evaluate the fate and effects of stressors and to quantify cause– effect relationships in a multispecies context. Large stream mesocosms are very rare. The high costs of construction and maintenance greatly limit the number of replicate streams and potential for variety in experimental design.
