Tufa Deposition in Karst Streams Can Enhance the Food Supply of the Grazing CaddisflyMelampophylax mucoreus (Limnephilidae)

Abstract

We studied the effect of carbonate depositions covering stone surfaces on the growth of larvae and the biomass of subsequent adults of the grazing limnephilid caddisfly Melampophylax mucoreus (HAGEN, 1861) in a laboratory rearing experiment. M. mucoreus is mainly distributed in karst streams characterized by calcium carbonate precipitations (tufa). We reared larvae of M. mucoreus on stones covered by calcareous tufa crusts as well as on stones from which these crusts were experimentally removed to assess the influence on larval growth and the subsequent adult biomass. The rough surface of the covered stones provided a higher complexity of micro-habitats and supported algal growth compared to the smooth surface of stones without crusts. Larvae of M. mucoreus profited from the enhanced algal biofilm growth on the calcium carbonate precipitation indicated by faster larval growth and higher subsequent adult biomass. Biomass increase of larvae reared on stones covered by tufa crusts exhibited a faster biomass development (0.09 ± 0.015 mg/d) compared to the larvae reared on stones without crusts (0.06 ± 0.002 mg/d). Adult males (5.13 ± 0.25 mg) and females (7.64 ± 0.63 mg) were significantly heavier in the treatment with stones covered by tufa than their conspecifics from the treatment with uncovered stones (males: 4.26 ± 0.25 mg, p = 0.047; females: 4.96 ± 0.47 mg, p = 0.001). Additionally, males from the treatment with crust covered stones emerged significantly earlier (p = 0.003) than the males from the other treatment, whereas no significant difference was found for females. IntroductionCalcareous deposition on surfaces of submerged substrates is a typical phenomenon in spring-fed and groundwater dominated karst streams (DRYSDALE, 2001). The precipitation of calcium carbonate can build up considerable tufa crusts of several centimetres covering all present substrates, sometimes even leaves, caddisflies cases and mussel shells. Carbonate tufa streams, particularly small spring brooks are a characteristic type of karstic stream systems, often characterised by a temporary discharge regime (MEYER et al., 2003). The precipitation of calcium carbonate can be increased in carbonate-rich streams during periods of low flow (SZRAMEK and WALTER, 2004).Few effects of tufa crusts on the benthos in streams have been described, such as reduction of gammarid mortality caused by fish predators due to protective tufa deposits on the gammarid body surface (RUFF and MAIER, 2000) or increasing ciliate species diversity and higher periphyton biomass associated to increasing rate of tufa precipitation (PRIMC-HABDI- JA et al., 2001). On the other hand, animal activities can also promote tufa development in Internat. Rev. Hydrobiol.

Calcite deposition in karst waters is promoted by leaf litter breakdown andvice versa

“…In our study we did not observe any such inhibition. Phosphates may have been evacuated from the solution by colonizing microorganisms (Kock et al, 2006) which additionally produce extracellular polymers that become good places for nucleation of crystals. Moreover, colonized autotrophs utilize the CO 2 thus further promoting the calcite deposition.…”

Community–habitat relationships in coastal streams in Big Sur, California, USA: travertine influences macroinvertebrate abundance and community structure

“…Casas & Gessner (1999) found that carbonate deposition on leaves slowed breakdown rates in a Mediterranean stream in Spain, apparently by reducing both physical fragmentation and biological decomposition. In an experiment in a German stream, Kock et al (2006) found that travertine deposits on stone surfaces increased algal biomass and led to higher larval growth rates and higher adult mass of Limnephilidae caddisflies. Carbonate deposits that formed on the exoskeleton of Gammarus (Amphipoda) reduced predation by salamander larvae in an experiment in another German stream (Ruff & Maier, 2000).…”

“…Several studies have suggested that macroinvertebrate abundances are lower in travertine than in nontravertine reaches in both substrate cementing/layerforming (Minckley, 1963;Oberlin et al, 1999;Pitois et al, 2003;Alvarez & Pardo, 2007) and channel damming (Carter & Marks, 2007) types of travertine. Travertine deposition also may affect the abundance of algae (Pentecost, 1991;Kock et al, 2006) and leaf decomposition rate (Casas & Gessner, 1999;Carter & Marks, 2007), which potentially may affect macroinvertebrates indirectly through food resources. Whether travertine influences macroinvertebrate community structure, however, is among the issues that have not been addressed.…”

Response of periphyton to nutrient addition in a tufa-depositing environment

“…Tufa formation is also responsible for increasing the habitat surface for diverse organisms (Pentecost 2005). The rough surface of the tufa-covered substrate provides greater microhabitat complexity, and it supports increased algal growth compared to sediment without encrustations (Kock et al 2006). At sites of active tufa deposition this deposit is not only a substrate upon which periphyton develops: tufa is also embedded within the periphyton matrix, i.e.…”