Oceanography

The sea is a vast biological environment, home to the most varied forms of life, both plant and animal. While the higher plants are almost all terrestrial, countless lower plants are born, live and die within the waters of the ocean. The animal kingdom, too, has numerous representatives in sea water. They provide a good part of human food, as well as a varied number of organisms which, though of no importance to the human economy, challenge the curiosity of scientific observers.

The study of oceanography is still very backward in Madeira. Nevertheless, we already have some valuable descriptive or taxonomic works on various groups of organisms that live in the sea. Although they do not always meet the demands of modern hydrobiology, they are nonetheless very useful for understanding the composition of the fauna and flora of our waters.

The articles Algae, Carcinology, Shells, Fishes, Starfish, Sea Urchins, Worms, etc., etc., contain some information on the animal and plant life of our seas. However, the results obtained so far, chiefly through fishing and dredging, though they represent a great step forward in the investigation of the organisms living in our marine environment, shed little light on certain questions of oceanography that greatly occupy the attention of modern scientists. The plankton – the whole body of plants and animals that float passively in the water and are therefore at the mercy of the currents and of the physical and chemical conditions of their environment – has been very imperfectly studied. The same can be said of certain benthic groups, that is, those that are active near the sea floor. The study of ecological factors such as temperature, salinity, dissolved gases, pressure and the movement of the water in our seas, etc., has hardly begun. On the organisms of the plankton, or planktonts, which play a dominant role because of their abundance, only a few brief notes have been published, on the Madeiran Copepoda and Diatomaceae. Nothing is known, as far as we are aware, about the Dinoflagellata, and of the Cystoflagellata only Noctiluca miliaris is known, a very common organism in our waters which causes phosphorescence at night.

There has been much talk lately (1921) of establishing an oceanographic museum in Funchal. If such an institution is to be created and to prove truly useful, however, the study of the organisms of our waters must be given far wider scope than it has had until now. It is not enough for the museum’s cabinets to display fishes, crustaceans, shells, anthozoans, echinoderms and other groups whose size is enough to catch the attention of those untrained in the natural sciences. There must also be room for the bacteria, flagellates, green algae, foraminifera, ciliates, radiolarians, tunicates and other groups of plants and animals that characterise ocean waters and in many cases belong to the realm of plankton. Installing aquaria designed to reproduce the conditions of the marine environment would be highly advantageous, since it would allow observations that are difficult to make in any other way.

Equipping expeditions to study the fauna and ecological factors of the great depths is undoubtedly very costly, because of the ship, the apparatus and the men required. If our aims are more modest, however, and we wish only to study the faunal and floral composition of the waters of the bay of Funchal or of those near our coast, it is enough to turn to the fishermen’s tackle, to Muller nets improved for collecting plankton organisms at various depths, to wide-meshed nets and wide-mouthed jars for the macroplankton, and to dredges for collecting the organisms that live in contact with the bottom.

A boat, which need not be very large, and a few jars of fixative and preservative fluids complete the equipment needed for small-scale oceanographic exploration. If those who own boats and practise water sports were to spend part of their time afloat collecting marine organisms, our local oceanographic knowledge, which, as we have said, is still very limited, would advance considerably. It is plankton above all that calls for the attention of friends of the natural sciences. Although the study of the microorganisms that make it up is sometimes difficult, it must not be forgotten that many of these difficulties can be overcome with some effort and work, and others by seeking the enlightened advice of specialists, who as a rule do not refuse their help to beginners who show zeal and love for the research to which they themselves are devoted.

Because they bear closely on the subject of this article, we transcribe the following passages from the valuable work by the engineer Adolfo Loureiro, Os Portos Marítimos de Portugal e Ilhas Adjacentes (V-21):

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It is known that Madeira lies in the region of the great ocean currents that flow through the liquid part of our planet. From the very beginning, ever since the discovery of Madeira, it was noticed that ships sailing from this island towards the Canaries were imperceptibly carried from N. to W. The current setting towards SSW ran at 12 to 16 miles a day, and was attributed to the action of the wind. On the north coast of Madeira, and especially at Porto da Cruz (‘harbour of the cross’), the sea sometimes brought unknown fruits, which were supposed to come from the W. The temperature found in the waters seemed to follow persistent laws and phenomena. Since the inhabitants of Madeira included seafarers and men who knew the sea, these facts did not escape them, and it is even believed that Christopher Columbus was led by them to conjecture that there must be lands to the west from which those samples of fruit came.

The temperature of the waters and its distribution at the surface, their periodic movements and conditions, following a law that seemed constant, ought to have become the subject of very interesting oceanographic studies, which unfortunately were never carried out.

It was also recognised that the depth conditions of this sea were exceptional: already very great close to the coast, the depth increased rapidly towards the Azores, ranging from 1,650 to 2,675 braças.

To the north of Madeira, 120 miles from the coast, it was 1,650 braças. Between Madeira and the Canary Islands it reached 2,298 braças. And between Madeira and the coast of Africa, as well as between Madeira and the Canaries, it reached 2,400 braças, being 2,225 only a short distance from the island.

As for the daily movements of the waters, or the tides, these phenomena have not been properly studied and recorded. The charts of the engineer Azevedo, for example, confirmed by various British naval officers, state that the establishment of the port (time of high water at full and new moon) at Funchal is 12 h 48 m, and the rise of the tide 2.28 m.’