Electrogenic sulfur oxidation in a northern saltmarsh (St. Lawrence Estuary, Canada)

Measurements of porewater O2, pH, and H2S microprofiles in intact sediment cores collected in a northern saltmarsh in the St. Lawrence Estuary (Quebec, Canada) revealed the occurrence of electrogenic sulfur oxidation (e-SOx) by filamentous “cable” bacteria in submerged marsh pond sediments in the high marsh. In summer, the geochemical fingerprint of e-SOx was apparent in intact cores, while in fall, cable bacteria were detected by fluorescence in situ hybridization and the characteristic geochemical signature of e-SOx was observed only upon prolonged incubation. In exposed, unvegetated creek bank sediments sampled in the low marsh in summer, cable bacteria developed only in repacked cores of sieved (500 μm), homogenized sediments. These results suggest that e-SOx is suppressed by the activity of macrofauna in exposed, unvegetated marsh sediments. A reduced abundance of benthic invertebrates may promote e-SOx development in marsh ponds, which are dominant features of subarctic saltmarshes as in the St. Lawrence Estuary.

A Non-Destructive Method for Dating Human Remains

The skeletal remains of several Native Americans were recovered in an eroded state from a creek bank in northeastern New Mexico. Subsequently stored in a nearby museum, the remains became lost for almost 36 years. In a recent effort to repatriate the remains, it was necessary to fit them into a cultural chronology in order to determine the appropriate tribe(s) for consultation pursuant to the Native American Grave Protection and Repatriation Act (NAGPRA). Because the remains were found in an eroded context with no artifacts or funerary objects, their age was unknown. Having been asked to avoid destructive dating methods such as radiocarbon dating, the authors used Optically Stimulated Luminescence (OSL) to date the sediments embedded in the cranium. The OSL analyses yielded reliable dates between A.D. 1415 and A.D. 1495. Accordingly, we conclude that the remains were interred somewhat earlier than A.D. 1415, but no later than A.D. 1495. We believe the remains are from individuals ancestral to the Ute Mouache Band, which is now being contacted for repatriation efforts. Not only do our methods contribute to the immediate repatriation efforts, they provide archaeologists with a versatile, non-destructive, numerical dating method that can be used in many burial contexts.

Foraging interactions between wading birds and strand-feeding bottlenose dolphins (Tursiops truncatus) in a coastal salt marsh

Strand-feeding is a unique foraging technique used by Atlantic bottlenose dolphins ( Tursiops truncatus (Montagu, 1821)) in salt marshes of the southeastern USA wherein a group of dolphins rushes a creek bank, temporarily stranding themselves to capture fish that have been pushed ashore by their bow wave. Wading birds are attracted to these events to forage on stranded fish. We hypothesized that birds foraging in association with dolphins experience greater foraging efficiency than birds foraging away from dolphins and that some birds are able to meet their entire daily metabolic needs by foraging at strand-feeding events. The species composition, abundance, and foraging success of birds at 569 strand-feeding events were compared with the same parameters from marsh surveys of birds not associated with dolphins. Only Great Egrets ( Ardea alba L., 1758) were proportionately more common at strand-feeding events than in the marsh overall (p < 0.001). During peak strand-feeding hours, energy intake per hour was higher for Great Egrets foraging with strand-feeding dolphins than for birds foraging away from dolphins (p = 0.04). Bioenergetic models indicated that prey intake by Great Egrets at strand-feeding events was sufficient to meet their existence and likely their active metabolic requirements.

Heavy Metal Tolerance of Fe(III)-Reducing Microbial Communities in Contaminated Creek Bank Soils

ABSTRACTFe(III)-reducing soil enrichment cultures can tolerate 100 μM Cu and Cd, 150 μM Co, 600 μM Ni, and 2,500 μM Zn. Metal-tolerant cultures were dominated byGeobacter-relatedDeltaproteobacteriaand Gram-positiveFirmicutesspp.(ClostridiaandSedimentibacter). A Cd- and Cu-tolerant Fe(III)-reducing coculture ofDesulfosporosinusandDesulfitobacteriumindicated the importance of theFirmicutesfor Fe(III) reduction in the presence of metals.