Murky waters in benthic quarters – the dynamic distribution of Hong Kong foraminifera, a reflection of coastal ecosystems in Anthropocene Asia

Abstract

Perched on the main drainage outlet for the Pearl River Delta Metropolitan Region, one of the most densely populated areas in the world supporting 1.2 billion people, is Hong Kong. Over recent millennia, this region has undergone sea-level rise, alternating salinities, delta progradation, monsoonal onset, and anthropogenic shoreline development and advancement. During this time, the marine communities of Hong Kong have endured substantial alteration and they’ve increased exponentially since the 19th century. Hong Kong has hosted some of the most polluted waters in the world and aggressive clean-up measures are increasingly being implemented, yet we have little information regarding both their past and present benthic communities. Recent research has established a stark water quality gradient stretching from more pristine eastern Hong Kong heading west to the increasingly polluted Pearl River Estuary, strongly influencing local coral community distribution, diversity and abundance. In 2016, cores (3 m) and surface sediment samples were collected to assess modern and palaeobenthic foraminiferal communities. Preliminary results reveal, surprisingly, flourishing modern communities that are distinctly controlled by strong local environmental parameters, generating very different assemblages across relatively small distances. When compared to palaeoassemblages, we can gauge benthic community change through these ecosystem upheavals and subsequent recovery, alteration or decimation. This work and ongoing analyses not only enables historical understanding of the area’s marine ecosystem development but comparing results to the last foraminiferal study some 30 years previous informs us regarding current environmental management protocols and their effectiveness since implementation.