Are solar activity and sperm whale Physeter macrocephalus strandings around the North Sea related

Abstract In the final decades of the last century, an increasing number of strandings of male sperm whales (Physeter macrocephalus) around the North Sea led to an increase in public interest. Anthropogenic influences (such as contaminants or intensive sound disturbances) are supposed to be the main causes, but natural environmental effects may also explain the disorientation of the animals. We compared the documented sperm whale strandings in the period from 1712 to 2003 with solar activity, especially with sun spot number periodicity and found that 90% of 97 sperm whale stranding events around the North Sea took place when the smoothed sun spot period length was below the mean value of 11 years, while only 10% happened during periods of longer sun spot cycles. The relation becomes even more pronounced (94% to 6%, n = 70) if a smaller time window from November to March is used (which seems to be the main southward migration period of male sperm whales). Adequate chi-square tests of the data give a significance of 1% error probability that sperm whale strandings can depend on solar activity. As an alternative explanation, we suggest that variations of the earth's magnetic field, due to variable energy fluxes from the sun to the earth, may cause a temporary disorientation of migrating animals.

SUSPENDED SEDIMENT DYNAMICS IN MANGROVE AREAS, DONG TRANH ESTUARY, CAN GIO MANGROVE FOREST, HO CHI MINH CITY, SOUTHERN VIETNAM

Joint Research on Environmental Science and Technology for the Eart

Seismic imaging of medieval dike remains in the Wadden Sea (North Frisia, Germany)

Dikes protected cultural lands along the Wadden Sea coast in medieval North Frisia. Remains of dikes must be found to reconstruct the drowned and lost landscapes. Certain imprints in sediment layers due to former load can be linked to eroded dikes. Sediment echosounding provides sections of these imprints and reveals dike courses. Medieval dikes have been traced at Hallig Südfall and south of Sylt