Marine pollution is a primary cause of eutrophication of surface waters, in which excess nutrients, usually nitrates or phosphates, stimulate algae growth. Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton and benthic animals, most of which are either deposit feeders or filter feeders. In this way, the toxins are concentrated upward within ocean food chains. Many particles combine chemically in a manner highly depletive of oxygen, causing estuaries to become anoxic. When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs. Once in the food webs, these pesticides can
Marine Biological Laboratory disease. Other marine organisms draw neuroscientists and neurobiologists to the MBL each summer, where a history of research into sensory physiology and behavior has been established. Haldan Keffer Hartline, an MBL summer investigator in the 1920s and early 1930s, uncovered several basic mechanisms of photoreceptor function through his studies on the horseshoe crab. Hartline shared the 1967 Nobel Prize with summer MBL colleague George Wald, who described the molecular basis of photoreception by showing that the light-sensitive visual pigment molecules consist of a slightly modified form of vitamin A coupled to a protein. Another long-term summer investigator, Stephen W. Kuffler,