Biology and Ecology of the Eucheuma Seaweed

(10) Soon after my recruitment as a Tutorial Assistant at the Department of Botany, University in Dar es Salaam, in April 1969,1 secured a research grant from the Norwegian Agency for Research Cooperation (NORAD), which enabled me to visit the coastal village communities along the entire coast of Tanzania, to learn about the distribution and biomass ecology of Tanzania’s Eucheuma species, and to understand the population dynamics of the seaweed. Indeed I must give due tribute to the late Professor Erik Jaasund, who was my first teacher of phycology, and through whose encouragement, I had applied for the NORAD research grant.

(11.) Through the NORAD-funded research project I learnt that:

· Eucheuma grows best in protected reefs behind coral reefs;

· requires clear, turbulent water, away from river mouths;

· thrives best at salinities of 30 to 35 ppt (i.e., close to open seawater salinity);

· does not grow in the upper intertidal habitats, but is more commonly found in the permanently immersed sub-tidal zone; and

· grows attached to any stable object in the sea, where the conditions for its growth prevail.

(12) During the field visits, I also learnt that Tanzania’s marine waters support a wide variety of other seaweeds with potential for industry, for export, and other applications. These include species of the genera Sargassum, Gracilaria and Hypnea. Additionally, I learnt that:

· most of the coastal villagers in Tanzania were poor, very poor, with a low standard of living;

· the soils in many of the villages were sandy, leached, with low crop productivity;

· the only reliable crops they grew were coconuts, and cashew nuts, which did not bring them quick returns;

· because of poverty, the fishermen in the coastal village communities could not afford appropriate fishing gear, and many were using dynamite as a fishing method. And they would dynamite off a coral reef, and kill a large population of fish, giving them quick monetary returns. But by doing so, they would, within seconds, devastate a rich ecosystem, which took millions of years to evolve. And by doing so they would also destroy the habitats where the very fish they wanted, were breeding. This thus meant that the biota in the coral reef ecosystems were endangered, and threatened of extinction.

(13) In the localities where the villagers were involved in harvesting Eucheuma for export, the methods of harvesting were also destructive in nature. The coastal communities essentially uprooted every Eucheuma plant they saw, without leaving basal stalks of the fronds for regeneration and re-growth. In the end I summarised my observations for publication, with recommendations on the need for better Eucheuma crop management practices. If you are interested to know what I had reported then, get a copy of Tanzania Notes and Records, volume 72, published in 1973 (pp. 19-36).

(14) Then I read the works of various other scientists who had also published their research findings on Eucheuma. The most impressive name that surfaced was that of Professor Maxwell S. Doty of the University of Hawaii, a real world authority on the Eucheuma seaweed. And I wrote to Dr. Doty, summarising my field study findings, and expressing my worries on the apparent over-exploitation of the Eucheuma seaweed in Tanzania. The outcome of my contact with Dr. Doty was that a few months later:

· I secured admission for my Ph.D. studies on seaweeds at the University of Hawaii;

· I won a Rockefeller Foundation Scholarship for my studies in Hawaii;

· Dr. Doty secured, for my wife and myself a travel grant (from Marine Colloids, company), which enabled us to make a brief (6 weeks) stop-over in the Phillippines, to participate in the pilot Eucheuma farming experiments in the southern Philippines, on our way to Hawaii.

At that material time, Dr. Doty had wanted me to share my research experience on the Tanzanian Eucheuma species with his field research staff, and to assist him with his field experiments on the pilot cultivation of the seaweed Eucheuma.

(15) So, in April and May 1970, my wife (Grace) and I got involved in those very first experiments on the cultivation of Eucheuma in the Philippines. We had just got married. And there I was, Dr. Doty volunteering to pay for all the honey-moon costs. You couldn’t have had it better! When we took off from Dar es Salaam, on April 15, 1970, one of the pieces of our accompanied baggage, was roll of dried Eucheuma specimens: 400 specimens in all, from the entire shoreline of Tanzania. I was confident then that I had more material that what I needed for my Ph.D. dissertation.

(16) During the six weeks in the Philippines I learnt that:

· Tanzania was then exporting a bigger tonnage of Eucheuma than the Philippines,

· Some of the species occurring in the Philippines (e.g., E. denticulatum and E. striatum) also occur in Tanzania, but there were also some taxa unique to each region;

· the habitat preferences of Eucheuma in the Philippines were similar to those observed in Tanzania, except that the Tanzanian localities are free of devastating typhoons (which is an advantage), and also experience a wider tidal amplitude (up to 4.0 m) than in the Philippines (only up to 1.0 m);

· vegetative fragments of Eucheuma supported on nylon lines in the sea showed an ability to regenerate, and to produce new frouds, if planted in appropriate habitats.

And in those six weeks I got valuable ideas on what I would do in Tanzania after my Ph.D. training in Hawaii.

(17) But, for my Ph.D. I decided to work on the genus Hypnea. Like Eucheuma, the Hypnea seaweed produces a hydrocolloid with properties which have good potential for industrial application. And please don’t ask me about the 400 specimens of Eucheuma which I had carried along with me to Hawaii. I would need more than an hour to tell the full story.