The impact of aquatic macrophyte (Salix sp. and Cladium mariscus (L.) Pohl.) removal on habitat conditions and macroinvertebrates of tufa barriers (Plitvice Lakes, Croatia)

Abstract

The effects of aquatic macrophyte (willows and sawgrass) removal on flow velocity, tufa deposition, POM dynamics, and macroinvertebrate community structure were studied in the tufa barrier habitats of the barrage system of Plitvice Lakes, Croatia. Samples were collected from two hydraulic habitats (fast > 100 cm s )1 and slow < 100 cm s )1 ) at both a control (no macrophytes removed) and impact (macrophytes removed) site. Samples were collected with a core sampler (four layers in vertical profile of barrier bed) monthly on 6 dates before and 7 dates after the removal of macrophytes. Macrophytes were removed in May 2002 at the impact site. After the macrophyte removal flow velocity decreased significantly at both hydraulic habitats. Retarded flow resulted in: (a) a decrease in macroinvertebrate density and diversity since most of the taxa were rheophilic (preferring habitats with higher flow velocity) and (b) an increase in POM concentrations (FPOM and UPOM) since decreases in flow velocity facilitate particle deposition in lotic habitats. The effects of macrophyte removal were present, and diminish along the vertical sediment profile of the barrier bed. Tufa deposition was not influenced by the macrophyte removal.

Long-term evolution of highly alkaline steel slag drainage waters

“…Indeed, monitored carbonate precipitation rates in the Dene Burn from mass balance estimates at equivalent Ca concentrations suggest calcite precipitation rates in the region of 0.6–0.8 g/m 2 /day (Hull et al 2014 ). These rates are similar to natural tufa-precipitating streams (Zaihua et al 1995 ; Miliša et al 2006 ) and do not have a major negative impact on the composition of macro-invertebrate communities in highly alkaline settings (Hull et al 2014 ). Following the decline in Ca apparent in the Dene Burn in the monitoring record, it would take between 52 and 80 years for such Ca values to be apparent in the Dene Burn assuming the monotonic trend continued.…”

Tufa Barriers from a Caddisfly's Point of View: Streams or Lake Outlets?

“…However, the distribution of Wormaldia species in microhabitats at tufa barriers encompassed in the current study seems to be primarily influenced by the specific feeding strategies and availability of particular fractions of organic matter at selected sites (WARINGER and GRAF, 1997;GRAF et al, 2002;, rather than by substrate type. Highest concentrations of FPOM in sediments at tufa barriers were recorded in habitats with slow current velocity (MILIŠA et al 2006b;MILIŠA, 2007). WIGGINS and MACKAY (1978) and GEORGIAN and WALLACE (1981) found that the distribution of philopotamid larvae usually depends on their feeding strategy, i.e., on high concentrations of fine organic particles.…”

“…The greatest part of water flows over the barrier, while a small part penetrates the porous structure and seeps slowly downstream, constructing a great variety of differing microhabitats (GOLUBIĆ, 1969;MILIŠA et al, 2006a). In microhabitats on tufa, various current velocity conditions associated with selective retention of organic matter have a major impact on macroinvertebrate community structure (HABDIJA et al, 2004;MILIŠA et al, 2006a;2006b).…”

Bryophyte communities and seston in a karst stream (Jankovac Stream, Papuk Nature Park, Croatia)

“…Most investigations on aquatic bryophytes have dealt with macrofauna (Suren, 1991;Habdija et al, 2004;Milisˇa et al, 2006b), while protozoa and metazoan meiofauna (i.e., pass through a 500 mm sieve, Fenchel, 1978) have been neglected. There are many studies on protozoa/ meiofauna in macrophyte stands (Sleight et al, 1992;Duggan, 2001;Bogut et al, 2010), but there are only few papers concerning these communities in bryophytes (Madalin´ski, 1961;Donner, 1972;Linhart et al, 2002).…”