Natural seasonal variations of the whole-body concentrations of six trace-metals in Mytilus californianus were determined by sampling fortnightly (‘biweekly’) for one year in a relatively pristine environment. Mussels of similar size were collected from a single mussel-bed, and within a discrete tidal range, in order to reduce variability unrelated to the availability of metals in the environment. The accumulation of iron, aluminium, and manganese, and to a lesser extent lead, was directly related to the input to inshore waters of terrigenous material via storm-generated runoff and bottom resuspension during the winter months.

Variations in the accumulation of copper appeared to be related to elevated concentrations of organic Cucomplexing compounds in the water-column both during the winter (e.g. humic acid, introduced via runoff) and during upwelling (e.g. extractable organic material from decomposing phytoplankton). Increased accumulation of cadmium by mussels during the spring was directly proportional to increased surface nutrient concentrations, indicating that Cd is upwelled to inshore waters.

Quantities of both Cd and Pb available to mussels during the Upwelling period appeared to be depleted by, and diluted within, the increased phytoplankton biomass present at that time. No relationship was observed between concentrations of any of the trace-metals analyzed and the reproductive condition of M. californianus.

This brief paper presents the information which we obtained in August 1980 on the habitats and endangered species of Viet Nam by interviewing scientists in both Hanoi and Ho Chi Minh City (Saigon). We did this with officials of the Department of Zoology of the University of Hanoi, of the Institute of Biology of the National Centre for Scientific Research, of the Technical Department of the Ministry of Forestry, and with others.

We were informed that Hylobates concolor (Whitecheeked or Black Gibbon) appears to be found in sufficient numbers to hold its own, but that H. pileatus (Pileated Gibbon) has been extirpated from Viet Nam. Pygathrix nemaeus (Douc Langur) also appears to be in no immediate danger of extinction. Bos sauveli (Kouprey), however, is said to be down to less than a dozen individuals in Viet Nam, and so little hope remains for this species. Lophura imperialis (Imperial Pheasant) has become even more rare than formerly and is in grave danger of extinction. The conifer Pinus krempfii also seems headed for extinction.

The coastal mangrove forest is the single most seriously disrupted habitat of Viet Nam. Some 40% of this highly productive ecosystem has been obliterated by military activities, and these war-obliterated areas are now largely covered by a low-growing, inferior vegetation or else have been converted to agriculture.

It is recognized that a comprehensive survey of the endangered species of Viet Nam is an urgent requirement, and that there is a pressing need for additional nature reserves. Economic conditions, however, seem to make early action improbable in both cases.

A comparative study of the floristic composition of aquatic vegetation growing in certain ponds in parts of Kerala, and those recorded as growing in the same ponds more than 20 years ago, reveals changes that are often extreme. Thus many of the once-dominant species have either dwindled or disappeared. In some ponds, most of the components of the original flora of only a quarter-of-a-century ago have been completely replaced by thick mats of Salvinia over the past two decades. Salvinia multiplies vegetatively very rapidly (cf. Mitchell et al., 1980), forming mats on which secondary colonists grow. This commonly leads to a gradual filling of the pond. Besides, Salvinia infestations also cause considerable loss of water from water-bodies through increased evapotranspiration. If these ecological processes are allowed to continue, many of our water-bodies seem sure to dry up in due course.

A well-planned and systematic method of control, involving physical removal—either through manual labour or specially-designed machines—to be followed by biological control (for example by grazing vertebrates or invertebrates), would keep the explosive spread of the weed under check. The huge mass of harvested weed could be utilized for production of organic manure, cooking gas, or hard-boards, or could be dried as packing material. There should also be vigilance by a surveillance squad of experts in the scientific disciplines concerned, which would be effective in preventing further spread of the weed—much as is already being practised with good results for the hydroelectric reservoirs of Kerala.

Aquatic resources in parks and reserves are not as adequately protected as comparable terrestrial resources. Thus the values of protected aquatic ecosystems as standards for comparison, reservoirs of genetic materials, and ‘emotional’ reserves, are apt to be greatly diminished.

Even seemingly static ecosystems such as coral reefs are dynamic, changing dramatically in response to natural short-term environmental variations. Such ecosystems require protected natural areas as dynamic standards that will allow distinctions to be drawn between effects of exploitation or pollution and normal variation. Furthermore, fisheries harvests may reduce the size at which exploited species mature, and reduce the amount and variability of genetic material produced by exploited populations.

The seven underwater parks or sanctuaries established since 1935 in Florida and the U.S. Virgin Islands exhibit wide variations in the degree of protection accorded to aquatic resources, a range being apparent from nearly complete protection in the first parks to be established to virtually no protection at all in the recently-established parks.

The consequences of permitting consumptive uses of aquatic resources in parks and reserves need to be objectively evaluated. Unless these consumptive uses are severely curtailed or eliminated, the primary values of the parks and reserves may never be realized.