Indo-Pacific humpback dolphin and land reclamation in Hong Kong

My final extended essay for my higher-level biology international baccalaureate explored the effect of the Hong Kong third runway and Hong Kong-Zhuhai-Macau Bridge reclamation projects on dolphin migration and territory use.

A Unique Brackish Habitat

The Chinese White Dolphin's (Sousa chinensis) habitat is delimited by the estuary containing a unique mixture of fresh water from the second largest river in China: the Pearl River Delta, mixing with seawater from the South China Sea. The dolphins favour this environment for the nutrients brought by the river that sustain prey on which it feeds on, as well as the chemical composition of the water to which it has adapted to survive (1).

Study area where unique mixture of freshwater from the Pearl River Delta mixes with the South China Sea (2)

A Species in Peril

The Chinese White Dolphin is known by many names: the Indo-Pacific humpback dolphin, the Chinese white dolphin or most commonly the Pink dolphin. However, this species has been seeing rapid decline over the past few years leaving a dire estimate of only 61 dolphins as of 2012 according to the Hong Kong Agriculture, Fisheries and Conservation department. The construction plans for a third runway for the Hong Kong airport as well as a major plan to build the world's longest sea crossing: the Hong Kong-Zhuhai-Macau Bridge greatly endangers the pink dolphin's habitat (3).

Hong Kong–Zhuhai–Macau Bridge (2018) (4)

Travel Corridor Cut-offs

By working with the University of Hong Kong's pink dolphin expert: Dr. Samuel Hung in alliance with the Hong Kong Dolphin Watch crew, data in dolphin territory and sightings were used to determine core hot spots of habitat use and identify commonly used travel corridors. We discovered that at least 25% of dolphin territory would be lost due to land reclamation. However even more of the territory is likely to be lost due to the disruption of two focal travel corridors between core sites for habitat use. The added impediment to reach these core sites will likely cause the loss of accessibility to more dolphin territory than what is simply being occupied by the reclamation itself (5).

References

1. Wordie, Jason (2002). Streets: Exploring Hong Kong Island. Hong Kong: Hong Kong University Press. ISBN962-209-563-1.

2. http://en.wikipedia.org/wiki/Geography_of_Hong_Kong#mediaviewer/File:Pearl_River_Delta_Area.png photo credits to wiki user croquant created October 11 2007.

3. "China opens longest sea-crossing bridge". BBC News. 23 October 2018. Retrieved 28 October 2018.

4. Reference projects (Sika) 2018 (https://www.sika.com/en/reference-projects/hong-kong-bridge.html)

5. Tania Couture (2015). "The relationship between the Indo-Pacific humpback dolphin population and the development of reclamation projects in Hong Kong". UWC Atlantic College, I.B Extended Essay, Higher Level Biology - unpublished work.