Habitat-specific benthic metabolism in a Mediterranean-type intermittent stream

¹ Faculty of Science and Technology, Campus of Gambelas, University of Algarve, 8005-139, Faro, Portugal
² Centro de Ciências do Mar, Campus of Gambelas, University of Algarve, 8005-139, Faro, Portugal
³ Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar
⁴ Bieszczadzki Park Narodowy, ul Belzka 7, Ustrzyki Dolne 38-700, Poland
⁵ Department of Applied Ecology, University of Lodz, Banacha 12/16 Str., 90-237 Lodz, Poland
⁶ Centro de Investigação Marinha e Ambiental (CIMA) Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal

^* Corresponding author: kasiasroczynska@gmail.com

Received: 23 October 2015
Accepted: 9 March 2016

Abstract

A modified flow-through chamber method was used to measure gross primary production (GPP), net primary production (NPP), community respiration (CR) and associated environmental variables in an intermittent Mediterranean-type stream in Southern Portugal. Three common types of in stream habitats were targeted: cobble (C), cobble covered with filamentous algae (C+A) and leaf litter (LL). NPP, GPP and CR differed significantly among all three habitats. GPP increased with chlorophyll a and, less strongly, with photosynthetic active radiation and, therefore, was highest in C+A habitat. The highest CR was in LL and its variation was best determined by ash-free dry mass (AFDM) of plant litter. Higher respiration in LL was related to heterotrophic activity and, to a lesser extent, to autotrophic respiration associated with periphyton. We observed a decrease of production efficiency of primary producers with AFDM in C+A and C habitats. Our results demonstrate that each habitat type should be considered as a discrete metabolic entity and that particular sets of environmental factors are responsible for habitat specific metabolic responses. Scaling up measurements from discrete habitat patches to the entire reach or stream should not be done by extrapolating the results of a single habitat type and will require quantification of habitat coverage, at the appropriate scale.