Hydropsyche occidentalis

Banks, 1900

Hydropsyche occidentalis is a filter-feeding caddisfly in the Hydropsychidae, found in lotic (flowing water) streams of North America. It constructs fixed capture nets to filter organic particles from the water column, playing a significant role in stream function. The species has been studied for its bioenergetics and contribution to controlling organic transport in streams, where it can comprise a substantial portion of in suitable .

Hydropsyche occidentalis by (c) Don Loarie, some rights reserved (CC BY), uploaded by Don Loarie. Used under a CC-BY license.

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Habitat

Lotic (flowing water) streams, particularly in riffle where current facilitates filter-feeding. Documented from Deep Creek, Idaho, where it occurred at station 2 with mean of 2.45 g DW/m² and of 1786 individuals/m².

Distribution

North America; Nearctic region. GBIF records confirm presence in North America.

Diet

Filter-feeding on suspended organic particles in stream water, including diatoms and other seston. Mean ingestion rates measured at 29.2–31.3 mg DW/mg DW/h for diatoms in laboratory experiments; lower rates observed when green concentrations were high.

Behavior

Constructs fixed capture nets to filter particles from flowing water. Filter-feeding activity removes approximately 1% of seston flowing over the substrate daily. Digestion (gut-clearance) time ranges from 1.54 to 2.63 hours.

Ecological Role

Important filter-feeder in stream , processing suspended organic material and directing energy to higher . Serves as prey for insects and fish. Net growth of 69.6% indicates efficient conversion of ingested material to . In Deep Creek, Idaho, comprised 44% of total standing crop biomass during months of presence.

Similar Taxa

Simulium spp.Co-occurring filter-feeding insect in similar lotic ; both process suspended organic material but differ in bioenergetic parameters (Simulium has faster gut-clearance time of 0.33–1.25 hours vs. 1.54–2.63 hours for Hydropsyche, and lower net growth of 49.5% vs. 69.6%).

More Details

Bioenergetic Parameters

Respiration rate measured at approximately 2.3 μl O₂/mg DW/h at 20°C for water >62% O₂ saturation. Mean energy budget (J/mg/h): ingestion 0.393, respiration 0.042, growth 0.100, assimilation 0.192. Growth rates under natural conditions: 3.6–4.4 mg DW/mg DW/h.