The "Threat of Nutrient Overload"

The first objection I invariably get to my suggestion that we “feed the fish” is that there are already “too many” nutrients entering the ocean, and that in fact the problem is the reverse of what I say (it's not "starved" but "over-fed"). Major amounts of organic nutrients enter the ocean via run-off from land...I don’t deny the fact. But I have a different “take” on’s an excerpt from my book:

“Another concept that has really “muddied the waters” of thinking on the subject, is the notion of the “threat of nutrient overload.” The literature that I have seen on “threats” to the health of the oceans, whether from a scientific source such as the Smithsonian Institute, or from the many concerned environmental groups, invariably lists the “threat of nutrient overload.” This is based on the observation that in many heavily populated areas, the coastal waters, rivers and estuaries are looking quite murky these days, due to the large amount of waste from human activities that has drained into them. The problem sources are human sewage, the outflow from human sewage treatment plants and agricultural runoff, which contains large amounts of nutrients in the form of fertilizer (nitrates and phosphates) as well as animal manure. This stuff tends to be either in the form of tiny particles or actually as dissolved substances. Nutrients in this form are highly usable by phytoplankton or “algae,” and the result is an explosion of growth of these plants. The problem occurs when the overgrowth of algae sinks to the bottom and decomposes, where the decomposition process uses up most or all of the available oxygen in the water. The subsequent drop in the oxygen level causes all of the animals that need it (like fish) to die. One of the worst examples of this, that is frequently cited, is at the mouth of the Mississippi River. Apparently where this river empties into the Gulf of Mexico there exists a huge “dead zone,” where there are virtually no fish species alive.

This phenomenon of nutrient overload is called “eutrophication” in the scientific literature. I have no doubt that the process that happens is exactly as described, and that it really does make a mess, and that it really does cause fish to die. But it is only a local example of “too much of a good thing.” It is possible to ruin a garden with too much fertilizer, and that pretty well describes what happens in the coastal waters that are affected by this problem. But, just because we can see that it is muddied up around the edges in a few places, we cannot conclude that the open ocean or the system as a whole is suffering from an excess of nutrients. In fact just the opposite is true. Standing at the shoreline, maybe along side a polluted estuary, and looking out to sea, does not give any idea of how vast the ocean really is, or what the overall condition is like. Oceans are incredibly huge and because we are land animals, the part that we see most often is the bit that is beside the shore. But the messy condition of our polluted shorelines does not typify the whole thing, and just because it is all physically connected we must not conclude that it is “full of nutrients” everywhere.

The actions of tides and currents are very well known and predictable, but that does not mean that the water in the sea is effectively “stirred” to achieve a homogenous composition. The mechanism by which nutrients in coastal areas are spread to offshore areas is not well understood. The distinct character of the seawater in different places (degrees of clarity and temperature) helps convince me that overall, water in the system is not very effectively mixed. Also the mere fact that something like the huge “dead zone” off Louisiana can even occur, argues against a system of effective spread of nutrients through the seas Therefore, the ocean is sickened by too many nutrients in some relatively tiny coastal areas, and sickened by a serious lack of nutrients in the vast offshore areas.”

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