41. Deep ocean currents are driven by density and temperature gradients. 42. Shifts in ocean currents also might explain many climate changes. 43. Ocean currents , wind and other factors determine whether a carcass makes it to a beach.44. Pollutants from around the world are carried north by rivers, ocean currents and atmospheric circulation. 45. Strong westward ocean currents have carried alongside him a 15-foot raft, upon which he sleeps. 46. Adjacent ocean currents can define distinct, if shifting, boundaries. 47. Animals are hitchhiking " on the bottom of ships and with ocean currents , he said. 48. SWOT will track freshwater resources, and measure ocean currents . 49. Other theorize changing ocean currents or temperature may be preventing eels from coming into rivers. 50. Weather patterns and ocean current patterns are very interrelated.