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bioRxiv · 10.1101/2021.04.07.438801

What's the relative humidity in tropical caves?

Mejia-Ortiz, L.·Christman, M. C.·Pipan, T.·Culver, D. C.
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Abstract

Relative humidity (RH) was measured at hourly intervals for approximately one year in two caves at seven stations near Playa del Carmen in Quintana Roo, Mexico. Sistema Muevelo Rico is a 1.1 km long cave with 12 entrances and almost no dark zone. Rio Secreto (Tuch) is a large river cave with more than 40 km of passages, and an extensive dark zone. Given the need for cave specialists to adapt to saturated humidity, presumably by cuticular thinning, the major stress of RH would be its deviation from saturation. RH in Rio Secreto (Tuch) was invariant at three sites and displayed short deviations from 100% RH at the other four sites. These deviations were concentrated at the end of the nortes and beginning of the rainy season. Three of the sites in Sistema Muevelo Rico showed a similar pattern although the timing of the deviations from 100% RH was somewhat displaced. Four sites in Sistema Muevelo Rico were more variable, and were analyzed using a measure of amount of time of deviation from 100% RH for each 24 hour period. Strong seasonality was evident but, remarkably, periods of constant high humidity were not the same at all sites. In most Sistema Muevelo Rico sites, there was a detectable 24 hour cycle in RH, although it was quite weak in about half of them. For Rio Secreto (Tuch) only one site showed any sign of a 24 hour cycle. The troglomorphic fauna was more or less uniformly spread throughout the caves and did not concentrate in any one area or set of RH conditions. Compared to temperature, RH is much more constant, perhaps even more constant than the amount of light.

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Mejia-Ortiz, L., Christman, M. C., Pipan, T., Culver, D. C.. 2021-04-07. What's the relative humidity in tropical caves?. https://doi.org/10.1101/2021.04.07.438801

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