Local Chinese White Dolphins Threatened by Heavy Metals and Pollutants
Local Chinese White Dolphins Threatened by
Heavy Metals and Pollutants
OPCFHK Steps Up Conservation Research Studies to Learn More
(9 January 2014 – Hong Kong) Ocean Park Conservation Foundation, Hong Kong (OPCFHK) has long led efforts in protecting Chinese white dolphins (CWD). Preliminary findings of research funded by OPCFHK show that CWDs in Hong Kong waters and across the Pearl River Estuary (PRE) have been exposed to organic pollutants and heavy metals, including lead and mercury. These pollutants can damage CWD’s nervous, immune and reproductive systems, as well as the detoxification function of their liver, putting the species’ long-term survival and sustainability under serious threat. These findings add weight to previous predictions that the CWD population in the PRE could fall by 74% over the next 60 years. Anticipating a possible increase in cetacean stranding incidents in the next few years if water pollution worsens, OPCFHK’s Cetacean Stranding Response Team, with support from Ocean Park’s highly experienced veterinary and marine mammal team, will remain vigilant in monitoring for stranded CWDs in Hong Kong waters. The Foundation will also continue to supply Sun Yat-sen University with samples collected from locally stranded dolphins to facilitate toxicology and other studies critical to the formulation of conservation strategies.
Ms Suzanne Gendron, OPCFHK’s Foundation Director, said, “OPCFHK is committed to the conservation of CWD through stranding response and funding research. In 2013, we recorded 28 cases of cetacean stranding, including nine CWDs of which five being neonates or calves with body length less than 1.2m. To help uncover factors that might be driving strandings and impacting the species’ long-term survival and sustainability, we have been consistently funding CWD-related research. A key series of projects involve our collaboration with Sun Yat-sen University to build China’s largest CWD DNA Bank and Marine Specimen Bank over the past two years. These critical resources enable researchers to investigate and track the health status and environmental conditions of CWDs inhabiting Hong Kong and across the PRE. Preliminary findings paint a deeply worrying picture as diverse pollutants had been detected in samples collected from stranded CWDs. For the fiscal year of 2013/14, we are funding six CWD-related projects for a total amount of HK$1.26 million. Building on our previous support for data banks, one of the funded projects involves the development of an information library of biochemical indictors that reflect the diet, accumulation of pollutants, detoxification mechanisms and other key measures.”
Prof. Wu Yu-ping, School of Marine Sciences, Sun Yat-sen University, is the principal investigator leading the establishment of the CWD-related specimen banks and the new project on biochemical indicators. Prof. Wu said, “As one of the most economically developed areas in China, the PRE is the source of a variety of organic and inorganic pollutants that can be harmful to CWDs. These pollutants include pesticides used by the local agricultural sector, PCB (polychlorinated biphenyls)-related products generated by industries, and inorganic substances consisting of heavy metals, all representing the leading pollutants in the region. The levels of heavy metals such as mercury, lead and arsenic in the sediment samples from some parts of PRE waters are much higher than those found in the Yellow River and Yangtze Estuary.”
Prof. Wu added, “Different pollutants affect different organ systems of CWDs. Firstly, organic pollutants like pesticides and PCBs can harm the CWD’s immune and reproduction systems, inducing tumours and leading to a decline in the reproduction rate. CWD calves and foetuses can also be exposed to pesticides from the mother’s milk and through the umbilical cord, resulting in a lower chance of survival. Secondly, pollutants like DDT (dichlorodiphenyltrichloroethane) can also disrupt CWD’s nervous system. With its high solubility in fatty tissue particularly in dolphins’ melon, it could potentially affect the dolphin’s echolocation ability and influence the dolphin’s normal predation and activities as well as heightens the risk of accident. Thirdly, the accumulation of heavy metals like mercury can undermine the detoxification function of CWD’s liver and central nervous system, thus worsening their overall health and reproductive ability. Even more concerning is that tissue samples show an increase in levels of selenium, a toxic trace element, over just the past three years.”
Being one of the leading funders of conservation projects among zoos and aquariums worldwide, Ocean Park is committed to supporting scientific research and marine conservation. Dr. Lee Foo Khong, a veterinarian at the Park, said, “Ocean Park is committed to supporting OPCFHK through year-long funding, personnel resources, and logistics support.. Ocean Park also supports OPCFHK’s Cetacean Standing Response Team with technical expertise through our veterinarian team and the Marine Mammal Department. For example, the veterinarian team is responsible for conducting thorough necropsies on freshly or moderately decomposed carcasses using the Park’s facilities, with the aim to understand the cause of death and health status of the stranded cetaceans in Hong Kong. Veterinarians also assist the Response Team in collecting cetacean samples to be passed to universities and research institutes, including Sun Yat-sen University. With extensive expertise in cetacean care, Park staff has also handled live stranding cases by caring for the rescued animals at Ocean Park a few years ago. Keen to share knowledge with fellow researchers and conservationists in Guangdong Province and in the region, our cetacean experts took part in the first Southeast Asia Marine Stranding Symposium and Workshop in February 2013, which was attended by 67 participants from nine Asian countries. Subsequent stranding training workshops on first response and dolphin necropsy were conducted in Indonesia twice in 2013.”
The latest research findings on the health status of CWDs across the PRE are the results of OPCFHK’s continuously expanding commitment to systematic research on the species. In 2011/12, the Foundation funded the establishment of a China’s largest CWD DNA Bank at Sun Yat-sen University, which offers a standardised platform for scientists to better understand the genetic diversity of CWD and how they adapt to environmental changes. In 2012/13, the Foundation further funded the establishment of an additional Marine Specimen Bank to collect additional samples, including ecologically representative marine environmental specimens and other marine mammal samples. For 2013/14, OPCFHK again strengthened its support of CWD conservation by funding the development of an information library of analyses and data covering the diet structure, health status and detoxification mechanisms of CWDs, as well as the environmental conditions of their habitat.
Ms Gendron added, “On average, 74% of the current population is projected to be lost in three generations. At this point, the most urgent step is to improve the water quality in the PRE. To better understand the impact of pollutants, we plan to work with researchers to study the toxicology of stranded dolphins in Hong Kong. In the long run, OPCFHK will continue to strengthen our collaboration with research institutes and governments, support scientist in monitoring the living environment of CWDs and track population trends. All these will help conservation practitioners and decision makers formulate actions to be taken and help them devise sustainable conservation management strategies to protect the species. The coming Saturday is our 19th Ocean Park Conservation Day, which is themed under “Speak Up for Our Oceans”. We encourage the public to join us to learn more about our conservation efforts on CWDs, horseshoe crabs and seahorses at education and game booths, and make a pledge to help make a difference now. Ocean Park will turn paid admission into research funding to protect Asian wildlife”
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