Marine-dumped waste tyres cause the ghost fishing of hermit crabs

Poorly managed waste tyres pose serious environmental and health risks, ranging from air pollution caused by fire, leaching of heavy metals and outbreaks of mosquitos, to destruction of vegetation and coral reefs. We report a previously unrecognized ecological risk to marine organisms from waste tyres. Over 1 year, we made monthly counts of hermit crabs ( n = 1278) invading and/or being trapped within six tyres anchored to the seabed at 8 m depth in Mutsu Bay, Japan. A complementary aquarium experiment in which hermit crabs were released into a tyre confirmed that they could not escape. We report marine-dumped waste tyres to ghost fish in a manner analogous to discarded fishing gear. Because hermit crabs play important roles in coastal food webs as both prey and scavengers, declines in their numbers as a consequence of this ghost fishing might affect coastal ecosystems.

Centennial- to millennial-scale change of Holocene shallow marine environments recorded in ostracode fauna, northeast Japan

Using the record of shallow-marine ostracode fauna and sediment grain size data from an 865-cm-long piston core obtained from Mutsu Bay, northeast Japan, paleoceanographic changes of the bay were determined at high resolution for the early to middle Holocene. Changes in the relative frequencies of several species showed periodicities of 1300–1800 years similar to Bond cycles. At around 10,300 cal yr BP and again, at 9500–9300 cal yr BP, cold water strongly influenced the bay owing to cooling events. Since at least 10,200 cal yr BP the Tsugaru Warm Current influenced the surface waters, and since ca. 7400 cal yr BP, also the bottom waters of the bay. Since ca. 8400 cal yr BP the water depth rapidly increased and peaked at 7000–5900 cal yr BP due to global sea-level rise. Subsequently, a drop of water temperature and sea level in the bay at 5900 and around 4000 cal yr BP influenced the composition of the ostracode assemblages. These millennial-scale oscillations in relative sea level and bay temperature during the Holocene can be correlated to paleoclimate records elsewhere.

Low-Level Easterly Winds Blowing through the Tsugaru Strait, Japan. Part II: Numerical Simulation of the Event on 5–10 June 2003

This paper investigates the structures of and diurnal variations in low-level easterly winds blowing through the Tsugaru Strait and Mutsu Bay on 5–10 June 2003 using a numerical weather prediction model. Cool air that accompanies prevailing easterly winds owing to the persistence of the Okhotsk high intrudes into the strait and the bay below 500 m during the nighttime and retreats during the daytime. This cool-air intrusion and retreat induce diurnal variations in the winds in the east inlet of the strait, in Mutsu Bay, and in the west exit of the strait. In the east inlet, a daytime increase in air temperature within the strait produces a large air temperature difference with the inflowing cool air, and the resulting pressure gradient force accelerates the winds. The cool air flowing into Mutsu Bay is heated over land before entering the bay during the daytime. The resulting changes in cool-air depth and in pressure gradient force strengthen the daytime winds. In the west exit, local pressure gradient force perturbations are induced by the air temperature difference between warm air over the Japan Sea and cool air within the strait, and by variations in the depth of low-level cool air. The accelerated winds in the west exit extend southwestward in close to geostrophic balance during the daytime and undergo a slight anticyclonic rotation to westerly during the nighttime owing to the dominance of the Coriolis effect.