The observations made by scientists on a research voyage in the North Pacific show
that the pollution by civilization has reached a phenomenal level. While their vessel
traversed 150 km in 8 h, they surveyed 12.5 km 2 of ocean surface. They counted
6 plastic bottles and 22 pieces of plastic, 4 glass bottles, and 12 fisherman's bobs,
1 piece of rope, I weather balloon, I piece of finished wood, 1 shoe brush, 1 sandel,
3 pieces of paper, and 1 coffee pot (Venrick et al. 1973).
Tourists at the beach are not only annoyed by clumps of tar, but by all sorts of plastic material as well. Floating pieces of plastiC foil are a danger for small craft, because
they can wrap themselves around the boat's propeller. At a specific density of 0.92,
pieces of plastic wrap float on the surface. Under the influence of the sun's rays,
the material changes and becomes heavier, and when small calcareous encrusting
Bryozoa settle on them they sink to the bottom where they are a nuisance. Fishermen in the Skagerak almost always find pieces of plastic foil in their nets when they
pull them up from a depth of 180-400 m (Holmstrom 1975). Threads and ribbons
can wrap themselves around fish and marine birds, and small pieces of plastic have
been found in the intestines of many marine animals.
70