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UID:pretalx-nss-convention-2026-CEKDDL@talks.caving.dev
DTSTART;TZID=EST:20260708T091000
DTEND;TZID=EST:20260708T093000
DESCRIPTION:Directed phytokarst comprises light-oriented pinnacles on limes
 tone surfaces in tropical cave entrances. Although these features have lon
 g been linked to phototrophic biofilms\, the mineralogical and geomicrobio
 logical processes responsible for focused dissolution of limestone remain 
 poorly understood. Given its exclusive identification under low-light cond
 itions\, we wondered whether far-red/near-infrared (FR/NIR)-driven photosy
 nthesis could trigger biochemical pathways that create this dissolution.\n
 \nWe examined directed phytokarst in Clearwater Cave (Gunung Mulu National
  Park\, Malaysia). Field observations indicate that phytokarst was restric
 ted to the twilight zone\, with the relative illumination (lux) decreasing
  from 619.1 lux at the entrance to 6.4 lux (~1% of entrance illumination) 
 in zones with well-developed phytokarst. Petrographic thin-section analyse
 s of the phytokarst revealed flat\, laminated calcite layers preserved alo
 ng a shared original rock surface\, supporting a dissolutional origin rath
 er than secondary mineral deposition\, while biofilms were densest at the 
 pinnacle base. Excitation emission matrix fluorescence spectroscopy demons
 trated red-shifted features in phytokarst-associated biofilms\, consistent
  with the presence of pigments that absorb and fluoresce at longer wavelen
 gths under FR-enriched illumination. Scanning electron microscopy revealed
  porous\, etching-like textures and microborings on carbonate surfaces\, s
 uggesting localized bioerosion at the biofilm–mineral interface. Illumin
 a sequencing identified potential NIR-capable cyanobacteria (including Aca
 ryochloris spp.) and green algal taxa.\n\nCollectively\, these observation
 s link cave-entrance light gradients to localized biofilm-driven dissoluti
 on\, explaining directed phytokarst confinement to twilight zones.
DTSTAMP:20260826T232305Z
LOCATION:205
SUMMARY:Directed Phytokarst: Red-Shifted Phototrophy and Limestone Dissolut
 ion in Cave Twilight Zones - 
URL:https://talks.caving.dev/nss-convention-2026/talk/CEKDDL/
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