10.7291/D1PQ36
Killam, Daniel
0000-0001-7569-1828
University of Arizona
Clapham, Matthew
University of California, Santa Cruz
Al-Najjar, Tariq
University of Jordan
Giant clam growth and isotope data
Dryad
dataset
2021
Paleobiology
conservation paleobiology
Sclerochronology
Bivalves
giant clams
tridacna
Red Sea
Carbon and nitrogen stable isotopes
2021-08-10T00:00:00Z
2021-08-10T00:00:00Z
en
1097672 bytes
3
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
The health of reef-building corals has declined due to climate change and
pollution. However, less is known about whether giant clams, reef-dwelling
bivalves with a photosymbiotic partnership similar to that found in
reef-building corals, are also threatened by environmental degradation. To
compare giant clam health against a prehistoric baseline, we collected
fossil and modern Tridacna shells from the Gulf of Aqaba, Northern Red
Sea. After calibrating daily/twice-daily growth lines from the outer shell
layer, we determined that modern individuals of all three species
(Tridacna maxima, T. squamosa and T. squamosina) grew faster than Holocene
and Pleistocene specimens. Modern specimens also show median shell organic
δ15N values 4.2‰ lower than fossil specimens, which we propose is most
likely due to increased deposition of isotopically light nitrate aerosols
in the modern era. Nitrate fertilization accelerates growth in cultured
Tridacna, so nitrate aerosol deposition may contribute to faster growth in
modern wild populations. Furthermore, colder winter temperatures and past
summer monsoons may have depressed fossil giant clam growth. Giant clams
can serve as sentinels of reef environmental change, both to determine
their individual health and the health of the reefs they inhabit.