Faunal engineering stimulates landscape-scale accretion in southeastern US salt marshes.

The fate of coastal ecosystems depends on their ability to keep pace with sea-level rise-yet projections of accretion widely ignore effects of engineering fauna. Here, we quantify effects of the mussel, Geukensia demissa, on southeastern US saltmarsh accretion. Multi-season and -tidal stage surveys, in combination with field experiments, reveal that deposition is 2.

Optimizing coastal restoration with the stress gradient hypothesis.

Restoration efforts have been escalating worldwide in response to widespread habitat degradation. However, coastal restoration attempts notoriously vary in their ability to establish resilient, high-functioning ecosystems. Conventional restoration attempts disperse transplants in competition-minimizing arrays, yet recent studies suggest that clumping transplants to maximize facilitative interactions may improve restoration success.

Chromosomes and stress.

The present investigation examines genotoxic effects of: prolonged periods of stress; the role of the endocrine system; and the relationship between psychogenic stress and chemical mutagens. Increased levels of both Sister Chromatid Exchanges (SCEs) and Chromosome Aberrations (CAs) were observed in male rats subjected to white noise of either 72 or 240 hrs duration, demonstrating that damage occurs during chronic stress. Rats subjected to foot-shock after having been either hypophysectomized or sham-operated, showed elevation of both SCEs and CAs, indicating that hormones in the hypothalamic-pituitary-adrenal axis do not play a role in genotoxic damage.

Serum vitamin A levels during tuberculosis and human immunodeficiency virus infection.

Vitamin A deficiency during tuberculosis and human immunodeficiency virus (HIV) infection has not been characterized. A cross-sectional study was conducted among HIV-infected adults with tuberculosis in Butare, Rwanda, in which 29% of the subjects had serum vitamin A levels consistent with deficiency (<1.05 micromol/L).