In general, China's marine ecology was ranked "good" last year, but offshore waters are still threatened by acute environmental problems, according to a report released on March 19 by the State Oceanic Administration.

The administration noted that the quality of seawater had improved overall, and marine biodiversity had remained stable.

During the summer season, 96 percent of China's territorial waters attained the first level of the government's quality standard for seawater-signaling the third successive year the standard had improved-while the area where the quality was designated as "poor" shrank by 3,700 square kilometers.

The distribution of abundant life forms, including plankton, corals and endangered or protected species, remained unchanged.

Areas used for aquaculture, waste dumping, and oil and gas drilling all maintained high environmental quality, as did "functional zones" such as beaches and coastal resorts.

Monitoring of sewage disposal at sea allowed the administration to conclude that the number of disposals that met national standards accounted for 57 percent of the total, and that the number had risen for each of the past three years.

The report also noted reductions in the occurrence and scale of "red" and "green" tides-ecological disasters caused by the proliferation of various types of toxic algae-in the nation's territorial waters.

At 3,679 sq km, the area affected by red tides was the smallest seen in the past five years, and had declined by 51 percent compared with the previous year.

However, despite the generally positive outlook, officials warned that the nation's coastal waters are still threatened by a number of environmental problems that will require urgent attention.

For example, levels of pollution levels are still far too high, while sewage outlets should be subject to more stringent regulation, they said.