Seeking for the best conditions for fish fossil preservation in Las Hoyas Konservat-Lagerstatte using microbial mats

Actuotaphonomic experiments demonstrate how microbial mats prevent or delay destructive processes. The rate at which carcasses are covered is a key to their preservation. Because of the growth rate of microbial mats depends on environmental conditions, a set of experiments have been carried out emulating the Barremian environmental conditions, analysed for temperatures at 14 & DEG;C and 26 & DEG;C (cooler and warmer seasons respectively) and atmospheric pCO(2) (1000 ppm). For this purpose, the microbial mats were grown in mesocosms within an environmental chamber. Variations in primary production were quantified by measuring changes in dissolved O2 concentration in the water. Zebrafish carcasses were laid on the mats, and their coverage rates were calculated from the daily surface area covered by the mat. The results showed that the fish was covered twice as fast at 26 & DEG;C, in coincidence with the highest values for the gross primary production and community respiration of the microbial mats. Therefore, for these Barremian conditions, the early stages of carcasses preservation would take place most effectively during the warmer seasons as decomposing activity would release nutrients that would enhance, together with temperature, the growth of mats.

Automated summary

Actuotaphonomic experiments show that microbial mats can prevent or delay destructive processes by analyzing the coverage rate of carcasses. The experiments simulated Barremian environmental conditions, measuring temperatures at 14°C and 26°C, as well as atmospheric pCO(2) of 1000 ppm. The results indicate that fish carcasses were covered twice as fast at 26°C, coinciding with higher gross primary production and community respiration of the microbial mats.