Valles Caldera Benthis Macroinvertebrate Survey

Jacobi, Gerald

Benthic macroinvertebrates were collected from four locations ( East Fork of the Jemez River, Jaramillo Creek, Indian Creek, and San Antonio Creek) in the Valles Caldera during October 2000. Collections were at locations determined by the USFS to be PFC (proper functioning condition) reference sections. lhree samples were collected at each location using a Hess type modified quantitative sampler (Jacobi 1978) from dominant substrates in the sections. Jaramillo Creek and Indian Creek contained angulate basalt rubble substrates while the East Fork of the Jemez River and San Antonio Creek contained finer gravel or sand substrates. All locations contained Elodea sp. and/or Ranunculus sp. as the dominant vegetation. Stream flows were less than 2 cfs and sample locations were in low gradient sections(< 1.3%). The East Fork of the Jemez River samples were collected near the origin of the stream flow, ie., a spring.