[B-PT02] Biomineralization and Geochemistry of Proxies

[BPT02-P04] Statolith chemical compositions of the Indian squid Uroteuthis duvaucelii reveals ontogenetic variation off Visayan Sea, Philippines

*Jessica Managa Legaspi¹, Tomoyo Okumura¹ (1.Kochi University, Japan)

Keywords:Statolith, LA-ICP-MS, Uroteuthis duvaucelii

Geochemical composition of the biogenic carbonates in marine organisms can record the environmental and ecological conditions experienced by the species. In the case of squids, calcareous structures, statoliths, are formed in statocysts undergo continuous growth throughout their life in the aragonite form. The confirmed daily growth rings within the statoliths serve as a chronological record of squid growth, which are storing information on the ecological conditions encountered by squids. The statolith chemical components such as calcium (Ca), strontium (Sr), barium (Ba), sodium (Na), and sulfur (S) are known to be associated with squid movement, indicating changes in both the marine environment and squid physiology. For example, Sr/Ca ratio is known to have a negative correlation with the temperature, while Ba/Ca suggests vertical movement of cephalopods. In addition, Na/Ca and S/ Ca are also reported to represent changes in the physiological characteristics of the squids (e.g., Liu et al. 2011). This research investigated the chemical compositional changes in various developmental stages of an Indian squid, Uroteuthis duvaucelii, by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Based on the results of the study, the concentration of Sr/Ca and Ba/Ca remained relatively stable throughout the different life stages of this species. This implies that it is likely to be restricted to shallow coastal waters rather than inhabiting deeper oceans. On the other hand, Na/Ca and S/Ca ratios showed a trend of change that varies from individual to individual, which indicated that these elements may be linked to its physiology. These findings imply that analysing elemental patterns can help trace ontogenetic squid movement. To enhance our understanding of these squid's movement and physiology, it is recommended that further examination of the relationship between environmental factors and the concentration of elements associated with these aspects.

Reference: Liu et al. 2011. Marine Ecology Progress Series 429:93-101.