engleski

Crustacean inflexibility on flow regimes in intermittent spring

Intermittent springs are spatially "captive" systems that support aquatic invertebrates well adapted to the periodic disappearance of the flow. Consequences of no flow events in the karst spring Krčić more than 100 days per year were related to general community shift. This study was assessed population biology of the numerically dominant crustacean species Synurella ambulans and hydrological variables in determining the functional adaptation on periodic desiccation. The spring was seasonally researched during the average years and extremes with a period of zero flow in summer or even whole autumn, and in the year characterised by a continuous flowing phase. The aims were: (1) to find differences in population density and structure with flowing phases (before desiccation vs flow resumption) and to seasonal variation of flow regimes ; (2) to confirm resilience traits to intermittency independent of flow regime ; and (3) to determine life-cycle adaptation to intermittency. The species was well adapted to changing currents, seasonal drying of spring and seasonal changing of living substrates. We have confirmed resilience traits to intermittency independent of flow regime by a drastic drop of population density in summer during a continuous flowing phase. The records of only a few ovigerous females in samples point on the adaptation of life cycle to spring desiccation, and the females appear to lay eggs in the subsurface environment inside capillary interstices of karst. Further studies on the ecology of this highly adapted species and its relation to hydrological regime are essential for the understanding of intermittent spring functioning.

karst spring ; flow regime ; Synurella ambulans ; population density

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