THE smokestacks of an aluminum factory belch white smoke high over this sleepy port on the Danube, while boats head downstream into thick marshlands nurturing the richest variety of birds and fish in Europe.Balanced precariously between heavily polluting industry and one of the last patches of wilderness in the country, Tulcea is at the center of a largely unnoticed battle between Romanian scientists and developers over the fate of the Danube delta. In the absence of either an effective general environmental law or a specific law on the delta, both sides think that time is on their side. Ecologists see the network of canals, floating islands, and reeds as a natural filter for at least some of the pollutants the river carries from its passage through eight countries into the Black Sea. Three hundred species of birds nest in or migrate through the delta, and 100 fish species swim in its waters. Developers value the delta for its potential to yield food and raw materials, as well as for possible construction contracts. Hailing creation of the Danube Delta Biosphere Reserve last autumn as "the most important decision which has been taken until now in Romania regarding the environment," Marian Traian-Gomoiu, a marine biologist who is governor of the delta reserve, is working to lock restrictions in place around hunting, fishing, agriculture, and construction. Dr. Gomoiu has marshaled experts in several research institutes, as well as visiting scientists from the World Wildlife Fund and the International Union for the Conservation of Nature, to start the arduous work of collecting data on the delta ecosystem. Engineers and agronomists of the Danube Delta Central, the conglomerate that had a monopoly on development projects in the delta before it was divided into 18 smaller companies last year, are keeping an eye on Bucharest, where legislation on administering the delta has been delayed repeatedly. "The restrictions have not yet been consecrated by law," Cornel Ivanov, director of the Eco-Delta Company, is quick to point out. "At this point, they are just recommendations. "We are still looking for a compromise between scientific and economic needs," Mr. Ivanov adds. The reserve encompasses 573,000 hectares (2,212 square miles) and includes the shifting waterways and islands of the delta, a lagoon system, and a stretch of the Black Sea shore with a band of sea up to the depth of 20 meters. It is to be divided into zones that are strictly protected, areas targeted for ecological reconstruction, buffer areas, and transition zones where traditional methods of agriculture and fishing and environment-friendly tourism will be permitted. This year, a government decree banned the use of pesticides in the delta, but that ban has not been locked into law. The parliamentary environment and agriculture committees have come to an impasse over the law on administering the delta, which was first drafted in February 1990. Agricultural representatives want to continue large-scale farming in the northwest section of the reserve - a practice that has caused more than a dozen lakes to disappear over the past decade. Construction companies want to continue building embankments and canals. Most of the projects were begun in 1982, when Romanian President Nicolae Ceausescu launched his Complex Program for Intensive Exploitation of the Resources of the Danube delta. Over half the delta was to be committed to agriculture, the fish industry, and forestry. But the government did not have enough money to complete the program. At least 30 percent of the planned canals have not been built. Like the tussles over rain forests in Latin America or wildlife habitats in Africa, the struggle in Romania is sharpened by the sense among many in this poor society that environmental protection is a luxury. "Immediately after the revolution, lots of people were saying we've got to pay attention to the delta, or we're going to see environmental disaster there," says Gheorghe Romanca, an official of the Environment Ministry's Office for Conservation and Ecological Rehabilitation. "But now they don't want to stop all the economic activities there. Their rationale is always the investments made to date." SOCIAL problems also loom large. Unemployment is rising rapidly in Romania; some say it could reach 700,000 of Romania's 11 million workers by the end of this year. Constantin Neagu, an inspector in the Tulcea Labor Office, says that almost 15 percent of salaried workers in the county are unemployed. Most of those were involved in the construction of canals and embankments, navigation, and industrial harvesting of reeds. The majority of these activities have been brought to an end by governmental decree. Most of the population on the delta, however, does not receive a salary. The Romanians and ethnic Russians, Ukrainians, and others who inhabit the delta live off the fish they catch and the produce they grow on small plots. Yet they, too, have suffered from the double pressure of a rapidly changing economic environment and the ravages of pollution. With the demise of the Danube Delta Central, fishermen are finding it difficult to return to their traditional means of existence. "For the first time I can remember, there are fishermen without work," says Petr Mocenko, editor of Romania's newspaper for the Russian minority, Zori. "In this transitional period, there are no possibilities for fishermen to become independent: They have no boats, nets, or even hooks." Gomoiu would like to introduce a ban on catching overfished sturgeon, which are valued for caviar, on the delta. But he admits that this is a quixotic hope, since it would alienate the fishermen who make up the bulk of the local population. The environmentalists know their support is crucial to protect the delta. The reserve plan includes programs to improve the standard of living in the delta. Most settlements there have no sanitation facilities, and people drink the river water. Last summer, 69 cases of cholera were reported in Romania. All had occurred in and around the delta.