Bioerosion drill holes increase carbonate dissolution in the planktonic foraminifer Globigerinoides ruber

Planktonic foraminifera are instrumental in reconstructing paleoceanographic and paleoclimatic conditions. However, preferential dissolution can significantly bias both assemblages and chemical compositions, leading to inaccurate interpretations. Bioerosional drill holes are commonly found in foraminiferal tests, yet whether these marks increase the tests' vulnerability to dissolution has not been analyzed. This study investigates whether drill holes affect the preservation of Globigerinoides ruber (comprising G. ruber albus and Globigerinoides elongatus) through an experimental approach. Sixty tests, extracted from a sediment core sample with high bioerosion levels, were categorized into four groups based on the number of drill holes (0-Control, I, III, IV). The tests were exposed to a buffered acetic acid solution and preservation was continually assessed through visual scoring and digital measurement of the test's areas. These controlled conditions allowed the quantification of dissolution effects over time. Our results reveal that bioeroded tests are significantly more susceptible to dissolution when compared to non-bioeroded ones. Tests with multiple drill holes (3 or 4) were especially vulnerable, showing rapid disintegration. Generalized linear models demonstrated that both the number and size of drill holes are key factors influencing the preservation indices. These findings emphasize the importance of accounting for bioerosion in paleoceanographic studies, as it compromises the tests preservation and potentially bias fossil assemblage interpretations. This study encourages testing dissolution susceptibility of other bioeroded species/assemblages from the fossil record under varying bioerosion levels and paleoceanographic settings. Furthermore, it highlights the importance of continued research into the impact of bioerosion-related variables on foraminiferal preservation.