Response and resilience of karst subterranean estuary communities to precipitation impacts

Abstract

The impact of meteorological phenomena on ecosystem communities of karst subterranean estuaries (KSEs) remains unknown. KSEs are characterized by vertically stratified groundwater separated by a halocline and host endemic aquatic cave‐adapted fauna (stygobionts). In October 2015, 8 days of heavy precipitation caused the first recorded mortality event in the KSE. This event was marked by a halocline shift 5 m deeper. The present study aimed to provide insights into resilience of KSEs faunal communities to temporal shifts in temperature and precipitation. Cave water temperature decreased on average 0.0068°C per mm of accumulated precipitation over 4 days, which can add up to, and surpass, the interannual temperature variation in cases of heavy precipitations. Biological surveys (2012–2021) conducted within cave systems El Aerolito and La Quebrada, in Cozumel, indicated that change in community structure was not detected and stygobionts were resilient; however, marine species inhabiting the caves were impacted. Overall, the faunal community at KSEs remains resilient within short‐term meteorological phenomena despite shifts of non‐stygobionts.

Are haloclines distributional barriers in anchialine ecosystems? Physiological response of cave shrimps to salinity

“…Haloclines in anchialine environments are dynamic in depth and magnitude of salinity difference, especially in conduits closer to the coast [ 12 , 14 , 15 ]. As the FG lens decreases during the dry season and water runoff to the coast is reduced, the halocline tends to decrease in depth gradually, and to change from FG to MG without an intermediate brackish layer [ 14 ].…”

“…When the rainy season recharges the FG lens, and flow to the coast becomes stronger, or due to storms that rapidly recharge the aquifer, salinity may drastically change in depth and extension causing long lasting effects in the groundwater habitat [ 15 ]. Such environmental changes have a significant impact on habitat availability and physiological stress, frequently resulting in fatal consequences for groundwater communities [ 12 ]. Thus, environmental changes in salinity may determine the distribution of species within groundwater environments [ 24 , 84 – 86 ].…”

“…Particularly, tropical storms have rapid and profound effects on the geochemistry of anchialine systems, as they impact oxygen availability, modify the salinity, and have long term (months) impacts the carbon cycle [ 15 ]. Such changes have a significant impact on habitat availability and physiological stress, which determine the distribution of species within these environments [ 12 , 16 , 17 ]. Because of the limited dispersal capacities of cave-restricted aquatic species (stygobionts), their evolutionary history is tied to the dynamics of these coastal aquifers [ 18 , 19 ].…”