Variation in brachiopod microstructure and isotope geochemistry under low-pH–ocean acidification conditions

Abstract

Abstract. In the last few decades and in the near future CO2-induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g. brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences for biomineral formation remain poorly understood. Only a few studies have addressed the impact of ocean acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789). These were grown in the natural environment as well as in controlled culturing experiments under different pH conditions (ranging from 7.35 to 8.15±0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy. Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low-pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2 source in the culture set-up. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.

The giants of the phylum Brachiopoda: a matter of diet?

“…; Ye et al . ) although an unpublished specimen from Huinay Station is 5 mm‐thick in section (Elizabeth Harper, pers. comm.)…”

Hard-Bottom Megabenthic Communities of a Chilean Fjord System: Sentinels for Climate Change?

“…Establishing a baseline can help in detecting early effects of acidification on fjords ecosystems; calcifiers organisms, such as gastropods and bivalves (e.g., Thomsen et al, 2012), and also CWCs (Turley et al, 2007) may represent valid sentinel species. Globally, brachiopods appear to be less impacted by ocean acidification (Cross et al, 2015(Cross et al, , 2016, probably thanks to compensating mechanisms (Cross et al, 2019), but microstructural changes have been observed in the shell of the Chilean fjords' species M. venosa (Ye et al, 2019). With warming and climate change seriously threatening these Chilean fjords benthic communities, it is imperative to reduce general stress levels on all organisms, and on the ecosystem itself.…”

The architecture of Recent brachiopod shells: diversity of biocrystal and biopolymer assemblages in rhynchonellide, terebratulide, thecideide and craniide shells

“…Brand et al 2011). Shells of the Terebratulida and Rhynchonellida are one of the most used biogenic structural materials for paleoenvironment reconstruction as they cover almost the entire geologic record, are wide-spread in marine habitats and, most of them, secrete low-Mg calcite shells (Al-Aasm and Veizer 1982;Veizer et al 1999;Brand et al 2003Brand et al , 2011Auclair et al 2003;Parkinson et al 2005;Angiolini et al 2009;von Allmen et al 2010;Payne and Clapham, 2012;Garbelli et al, 2012Garbelli et al, , 2014Cross et al 2015;Immenhauser et al 2015;Rollion-Bard et al 2016;Ye et al 2019;Jurikova et al 2020).…”