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Editor's note: Three years after writing the 'Declaration of Independence,' Thomas Jefferson drafted a bill 'for establishing religious freedom' in the state of Virginia. After declaring its independence from England, [...]

1. Coastal and estuarine waters are important ecosystems with high primary and secondary productivity, but they are prone to the impacts of habitat loss caused by anthropogenic activities. For species exclusively inhabiting coastal and estuarine waters, such as the Indo-Pacific humpback dolphin, Sousa chinensis, irreversible habitat loss can have dramatic implications for population viability. 2. A Landsat image database was used to determine the extent of coastal changes along the northern Beibu Gulf, where a large humpback dolphin population is found. The results were compared with the standardized sighting gradient (SPUF) determined from a questionnaire survey of fishermen and likely core habitats identified by application of a global digital elevation model. 3. Both SPUF and likely core habitat results indicated a continuous distribution of the humpback dolphin along the northern Beibu Gulf. Landsat images revealed that 129.6 km² of coastal waters were permanently lost in the past 40 years, 60 km² within the likely core habitats. Although this may be considered small, the impact of such habitat loss could be substantial in some local habitats. 4. The humpback dolphin population in the northern Beibu Gulf should be regarded as one management unit, with two or more social subunits. Immediate systematic surveys are needed to fill information gaps on true distribution range and habitat-use patterns. 5. Habitat protection actions for dolphins in the northern Beibu Gulf should include both core and linking habitats, including enacting protected areas in core habitats, mitigating anthropogenic impacts in likely habitats, restoring both coastal waters and surrounding landscape quality, effective treatment of industrial sewage discharge, and comprehensive environmental impact assessments for the planning of coastal development projects. [ABSTRACT FROM AUTHOR]

Studies on the distribution and habitat characteristics of the Indo-Pacific humpback dolphin (Sousa chinensis) indicate a general preference toward estuarine environments. However, quantitative connections between this preference and estuarine characteristics are seldom investigated. Distribution of the humpback dolphin in the northern Beibu Gulf, China, was evaluated through systematically designed surveys and was compared to oceanographic characteristics from on-board measured and remotely sensed variables. The humpback dolphins' core distribution zone, measured by the 50% kernel density estimate (50% KDE), was confined to the Dafengjiang River Estuary in a 50.23 km² area, with a steep-edged underwater sand bar below and locally high chlorophyll-a concentration. The surface salinity distribution showed an eco-cline environment in which riverine runoff mixes with sea water in the 50% KDE. We found significant relationships between distribution probability and two oceanographic variables: (1) water depth and (2) chlorophyll-a concentration. This associates the distribution preference of humpback dolphins with regional productivity and biodiversity peaks that may facilitate prey aggregation. As humpback dolphins inhabit comparable environments in other locations throughout their range, the oceanographic features of the 50% KDE may help to provide proxies to identify other key habitats over a broader spatial scale. [ABSTRACT FROM AUTHOR]

To the Editor.-- I am certainly not an advocate for frequent changes in laws and constitutions. But laws and institutions must go hand in hand with the progress of the [...]