Investigating the Local Reservoir Age and Stable Isotopes of Shells from Southeast Arabia

Abstract

We recently started a systematic approach to determine the reservoir age in southeast Arabia and its dependence on mollusk species and their environment. This part of the study concentrates on local reservoir age and stable isotopes of the lagoonal species Terebralia palustris and Anadara uropigimelana at Khor Kalba, Oman Sea. Environmental and nutritive influences on mollusks are reflected in the radiocarbon and stable isotope signal. We found a local reservoir age of A. uropigimelana of about 940 yr and that of T. palustris as 800 yr. Sclerochronological analyses yielded information about seasonality of growth and death in A. uropigimelana. The modern shell of Periglypta reticulata shares food resources and habitat with Anadara sp., of which we did not find a modern specimen. It provided information on response to changes in temperature in the lagoonal system needed for suitability as reflecting climatic conditions. We were interested in carbon pathways of the mangrove in Kalba and a mangrove planted anew on a former mangrove sediment in Ajman. Being an obvious source of charcoal and food of T. palustris makes this information necessary. Further analyses will be performed to interpret changes in reservoir age in complex lagoonal systems as reaction to environmental variability.

HLO1‐south: An Early Neolithic site in Wadi al‐Hilo (Sharjah, UAE)

“…Its shells are commonly found in large quantities at coastal sites in south‐east Arabia (e.g. Lindauer et al., with further citations). Terebralia lives in mangrove stands and is able to close its opening firmly with a lid at low tide or when it is taken from the water and transported overland.…”

Forgotten news: Shellfish isotopic insight into changing sea-level and associated impact on the first settlers of the Mariana Archipelago

“…However, the exact magnitude of error introduced by hardwater is considered to be dependent on the rate of water exchange with the open ocean (the "residence time") and therefore on current flow, the presence of bays and lagoons, freshwater hydrology and geology (Gómez et al 2008 and cannot be predicted by the presence of limestone alone. Moreover, the impact on shellfish depends on the habitat and dietary preferences of specific species and their tolerances for low salinity waters (Ascough et al 2005, Holmquist et al 2015, Lindauer et al 2017. Estuarine shellfish are more likely to be influenced by hardwater because of their preference to inhabit sheltered bays with reduced water exchange with the open ocean, but many mollusc species are tolerant of a range of water conditions (Reimer 2014, Hogg et al 1998 In environments where extraneous influences on 14 C are possible, shell δ 18 O and δ 13 C in combination with 14 C can help identify the cause of this offset.…”

Collapse of Holocene mangrove ecosystems along the coastline of Oman

“…As we encountered a lot of root-penetration structures in the paleolagoonal sediment, we presume that the main content of the remaining organic material in the sediment should originate from mangroves. It was already shown in another study (Lindauer et al, 2016) that mangrove leaves measured with radiocarbon provide atmospheric ages without influence from the marine environment because of photosynthesis. Younger sediment ages can be a result of bioturbation or younger mangrove roots growing into older sediment (Woodroffe et al, 2015).…”