Spring in the Ocean

Rachel Carson wrote Silent Spring in the 1960′s, one of the most important and influential books of the 20th century. But ten years previously she wrote another best-seller, The Sea Around Us. Carson was a biologist and in The Sea Around Us she stepped out of her familiar world and into the marine world.
Amongst Carson’s strengths were her ability to convey scientific ideas to a mass audience coupled with a clarity of language and an eloquence about the natural world.
The Sea Around Us hasn’t endured in the same way that Silent Spring has, primarily because some of the science is outmoded. Primarily that of the then accepted models of continental formation.
It’s odd to read The Sea Around Us with our clear understanding of one of the 20th Centuries great scientific ideas missing, that is Alfred Wegener’s Continental Drift or as we now call it, Plate Tectonics.

On that basis I wouldn’t recommend it wholeheartedly unless the reader has a reasonable science background.
However…
…all that was a preamble to the fact that there is some beautiful science writing in there, and not all of it inaccurate. I came across her chapter The Changing Year, about the seasons in the ocean in last year’s Oxford Best Science Writing of the 20th Century, a really great book, and decided to read the original.
That chapter stand as being both accurate and lyrical.
Here’s an extract:

“Spring moves over the temperate lands of our Northern Hemisphere in a tide of new life, of pushing green shoots and unfolding buds, all its mysteries and meanings symbolised in the onward migration of the birds, the awakening of sluggish amphibian life as the chorus of frogs rises again from the wet lands, the different sound of the wind which stirs the young leaves where a month ago it rattled the bare branches. These things we associate with the land, and it is easy to suppose that at sea there could be no such feeling of advancing spring. But the signs are there, and seen with understanding eye, they bring the same magical sense of awakening.

In the sea, as on land, spring is a time for the renewal of life. During the long months of winter in the temperate zones the surface waters have been absorbing the cold. Now the heavy water begins to sink, slipping down and displacing the warmer layers below. Rich stores of minerals have been accumulating on the floor of the continental shelf – some freighted down the rivers from the lands; some derived from sea creatures that have died and whose remains have drifted down to the bottom; some from the shells that once encased a diatom, the streaming protoplasm of a radiolarian, or the transparent tissues of a pteropod. Nothing is wasted in the sea; every particle of material is used over and over again, first by one creature, then by another. And when in spring the waters are deeply stirred, the warm bottom water brings to the surface a rich supply of minerals, ready for use by new forms of life.

Just as land plants depend on minerals in the soil for their growth, every marine plant, even the smallest, is dependent upon the nutrient salts or minerals in the sea water. Diatoms must have silica, the element of which their fragile shells are fashioned. For these and all other microplants, phosphorus is an indispensable mineral. Same of these elements are in short supply and in winter may be reduced below the minimum necessary for growth. The diatom population must tide itself over this season as best it can. It faces a stark problem of survival, with no opportunity to increase, a problem of keeping alive the spark of life by forming tough protective spores against the stringency of winter, a matter of existing in a dormant state in which no demands shall be made on an environment that already withholds all but the most meagre necessities of life. So the diatoms hold their place in the winter sea, like seeds of wheat in a field under snow and ice, the seeds from which the spring grow will come.

These, then, are the elements of the vernal blooming of the sea: the seeds of the dormant plants, the fertilizing chemicals, the warmth of the spring sun.

In a sudden awakening, incredible in its swiftness, the simplest plants of the sea begin to multiply. Their increase is of astronomical proportions. The spring sea belongs at first to the diatoms and to all the other microscopic plant life of the plankton. In the fierce intensity of their growth they cover vast areas of Ocean with a living blanket of their cells. Mile after mile of water may appear red or brown or green, the whole surface taking on the color of the infinitesimal grains of pigment contained in each of the plant cells.

The plants have undisputed sway in the sea for only a short time. Almost at once their own burst of multiplication is matched by a similar increase in the small animals of the plankton. It is the spawning time of the copepod and the glassworm, the pelagic shrimp and the winged snail. Hungry swarms of these little beasts of the plankton roam through the waters, feeding on the abundant plants and themselves falling prey to larger creatures. Now in the spring the surface waters become a vast nursery. From the hills and valleys of the continent’s edge lying far below, and from the scattered shoals and banks, the eggs or young of many of the bottom animals rise to the surface of the sea. Even those which, in their maturity, will sink do to a sedentary life on the bottom, spend the first weeks of life as freely swimming hunters of the plankton. So as spring progresses new batches of larvae rise into the surface each day, the young of fishes and crabs and mussels and tube worms, mingling for a time with the regular members of the plankton

Under the steady and voracious grazing, the grasslands of the surface are soon depleted. The diatoms become more and more scarce, and with them the other simple plants. Still there are brief explosions of one or another form, when in a sudden orgy of cell division it comes to claim whole areas of the sea for its own. So, for a time each spring, the waters may become blotched with brown, jellylike masses, and the fishermen’s nets come up dripping a brown slime and containing no fish, for the herring have turned away from these waters as though in loathing of the viscid, foul-smelling algae. But in less time than passes between the full moon and the new, the spring flowering of Phaeocystis is past and the waters have cleared again.”

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