Open AccessMarine crenarchaeotal membrane lipids in decapods: Implications for the TEX 86 paleothermometer
Author(s) -
Huguet Carme,
Cartes Joan E.,
Sinninghe Damsté Jaap S.,
Schouten Stefan
Publication year - 2006
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2006gc001305
Subject(s) - pelagic zone , benthic zone , oceanography , water column , zooplankton , mesopelagic zone , plankton , pelagic sediment , phytodetritus , geology , ecology , foraminifera , biology , sediment , paleontology
Pelagic Crenarchaeota produce glycerol dibiphytanyl glycerol tetraethers (GDGTs) as membrane lipids, and the GDGT composition changes according to growth temperature. This forms the basis of the TEX 86 paleotemperature proxy. This ratio correlates with sea surface temperature (SST) despite the fact that Crenarchaeota are distributed through the water column. Therefore there must be mechanisms that transport the surface signal to sediments such as repackaging in fecal pellets, marine snow, mass falls after phytoplankton blooms, or daily migration. To study GDGT transport, we analyzed stomachs and intestines of Atlantic and Mediterranean decapods as they are one of the major megafaunal groups, are easy to sample, and occur in both pelagic and benthic environments. GDGTs were found in most decapods' guts. GDGT abundances are significantly lower in intestines, but TEX 86 ‐derived temperatures are not significantly different between stomachs and intestines (<1°C), suggesting that TEX 86 values are not altered during gut transit. Atlantic decapods show no difference in TEX 86 values between benthic detritivors and pelagic predators. However, Mediterranean decapods show a substantial difference between macroplankton feeders and bentho‐pelagic predators. This is probably related to the freshness of the material consumed. TEX 86 ‐derived temperatures in Atlantic decapods are close to the SST around the time of sampling, in agreement with stomach content analysis that shows fresh organic matter being ingested. For Mediterranean decapods, TEX 86 temperatures are significantly higher than SST around the time of sampling. This can be partly attributed to the large variability between decapod specimens and the low amounts of fresh material found in their stomachs.