Macroconsumer Effects on Stream Benthos and Organic Matter Processing in a Tropical Headwater Stream: Are Shrimps More Active at Night?

Document Type


Publication Date



Stream macroconsumers are capable of influencing ecosystem processes and properties such as leaf breakdown, benthic community structure, and resource standing stocks. While several studies have addressed the individual influences of shrimps and fishes on litter decay and benthic environments, few studies have assessed the significance of nocturnal versus diurnal behavior of these consumers on ecosystem processes. We used an electric exclusion technique to assess the effect of macroconsumers on leaf breakdown and sediment removal in five blocks along a 130m stream reach in the Luquillo LTER. Each block contained electrified day and night frames, each with corresponding controls. We found no significant differences between the rates of leaf litter decomposition (P = 0.74) or organic sediment stocks (P = 0.45) in day, night, and control treatments. Despite the lack of significant effects, day shrimp exclusions had the highest rates of leaf decomposition (k = 0.010). No clear patterns were observed for organic sediment accrual in benthic substrates. Results suggest that shrimps can be equally active both nocturnally and diurnally and can thus influence patterns in ecosystem processes.


North American Benthological Society Annual Meeting (NABS)


Santa Fe, NM