The skyscrapers and urban development that have made Hong Kong the “Pearl” have also generated pollutants that affect marine species that inhabit Hong Kong’s coastal waters. Ongoing climate change and dams along the Pearl River have also altered these coastal ecosystems. However, it is largely unclear how they are changed, as we lack information on the baseline conditions at the time. “What were marine environments and organisms like in Hong Kong, say, 50 to 100 years ago, when human activity was much more limited? How were they different from what we see today? Dr Yuanyuan HONG, postdoctoral fellow from the School of Biological Sciences, Research Division for Ecology and Biodiversity and Swire Institute of Marine Science at the University of Hong Kong (HKU) raised the issue.
Fortunately, young fossils can help provide answers. Dr Hong and his team have used tens of thousands of tiny fossil shells preserved in seabed sediments to reconstruct Hong Kong’s marine ecosystem over the past 50 to 100 years. Using sophisticated measures of biodiversity recently developed by co-lead author Professor Anne CHAO of Taiwan’s National Tsing Hua University, Dr Hong found that climate and metal pollution played a role. major role in the formation of current marine communities in Hong Kong. The discovery was recently published in Anthropocene.
“Climate change, especially the weakening of the East Asian summer monsoon, has resulted in less rain and less freshwater discharge from the Pearl River, which has had a huge impact on marine life in the eastern waters of Hong Kong, such as Mirs Bay and Sai Kung. In addition, metal pollution from sewage and anti-fouling paints used on ships have significantly altered marine communities in central Hong Kong, such as Victoria Harbor, ”said lead author Dr Hong.
Significant impact on rare species
“Hong Kong’s eastern waters are much less polluted than central and western waters. However, these ecosystems are also much more sensitive to climate change. Future anthropogenic warming could reduce global ocean circulation and this could improve the summer monsoon in East Asia. in the eastern waters of Hong Kong may face increased Pearl River flows and lower salinity, higher turbidity and more muddy environments in the near future. Our research indicates that these environmental changes will particularly affect rare species. Most species in the tropics and subtropics of places like Hong Kong are rare, so anticipated changes can have a profound impact, ”explained co-lead author Dr Moriaki YASUHARA of the School of Biological Sciences, Research Division. for Ecology & Biodiversity, and the Swire Institute of Marine Science at HKU. .
Hong Kong is one of the largest coastal cities in the world and has one of the busiest ports in the world. Metal pollution, likely generated by sewage and anti-fouling paints used on ships, has affected marine life in Victoria Harbor, which is surrounded by Tsim Sha Tsui and Causeway Bay (two of the largest centers- cities). “The western waters of the Pearl River Estuary in Hong Kong are surprisingly resilient and resilient to climate and anthropogenic change. It is also surprising that eutrophication and deoxygenation did not show any substantial effect on the Hong Kong marine ecosystem in our study. The Pearl River estuary and the South China Sea in general are naturally rich in organic matter and nutrients from mega rivers and high rainfall, and deoxygenation in Hong Kong is not too severe compared to d other urbanized sea areas such as Chesapeake Bay next to Washington DC, Tokyo Bay next to Tokyo, and the Baltic Sea surrounded by many European cities. ”Dr. Hong developed further.
“Hong Kong remains” the pearl “even in the sea, as these regions continue to be home to extremely diverse marine life, but our research has shown that the climate and human activities have dramatically altered our local marine ecosystem in just 50 to 100 Underwater change is harder to see, compared to deforestation or other changes to the earth, ”concluded Dr. Hong.
Yet small fossils can reveal the history of underwater changes over the past decades, centuries or more. “Empty shells on the seabed allow us to ‘time travel’ to past marine ecosystems and determine the ways in which natural and anthropogenic environmental changes have shaped marine communities. Said co-lead author Dr Paul HARNIK of Colgate University.
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