Microhabitat use by Blennius fluviatilis in the Río Matarraña, Spain

Abstract

SUMMARY. Microhabitat use by Blennius fluviatilis in the Río Matarraña, Spain, varied significantly among dates during a 19‐month study. Most temporal variation, however, was attributable to changes in microhabitat availability. B. fluviatilis demonstrated non‐random use of available microhabitats during each sampling period, and generally occupied deeper microhabitats with higher average current velocities dominated by rubblegravel substrates. B. fluviatilis also demonstrated non‐random use of available nest sites; males generally nested under the largest available pieces of rubble, in areas with less gravel or sand. Water column depth influenced nest site use in two of four study areas. We found few microhabitat differences between spawning and nonspawning periods, or between males and females. In addition, microhabitat use was similar among B. fluviatilis size‐groups. Although B. fluviatilis often were over‐represented in deeper, erosional areas, blennies necessarily inhabited a wide range of microhabitats because average current velocities and water depths fluctuated greatly during the study. Tolerance of a broad range of environmental conditions may contribute to the species' persistence in habitats that exhibit extreme seasonal changes in discharge such as the Matarraña.