Mike van Keulen shares his thoughts about the field visit we had to Xincun Bay.
Photos and text by Mike van Keulen
As part of the ISBW11 activities, we were privileged to visit the Special Seagrass Protection Area in Xincun Bay near the Workshop location on Hainan Island. The bus ride to the site provided an interesting glimpse of the countryside near Sanya, with extensive areas of agricultural land. The bus trip was made more interesting by the disconcerting high temperature alarm that sounded throughout much of the trip; however both buses completed the journey successfully and the alarm was dispelled from our minds. Disembarking, we then boarded a small ferry for the short journey across Lian Port, bustling with commercial vessels and houseboats to Nanwan Monkey Island (no monkeys were observed in the making of this blog).
A short walk through the forest brought us to the shores of the Bay. The huge number of houseboats and aquaculture facilities was immediately striking as we emerged onto the beach. The Bay is semi-enclosed, with a relatively small opening to the open sea, which resulted in large amounts of rubbish accumulating in the shallows and on the beaches.
Not far from shore were many structures used in aquaculture and fish handling, as well as houseboats and other vessels. Clam harvesting from the intertidal using rakes was also in evidence, resulting in a very disturbed intertidal shoreline.
The pollution from the densely populated waterway and the aquaculture activities was very evident, with very turbid waters inshore and a high amount of particulate matter in the water column. The fine particulate matter was easily resuspended and doubtless compromises the light regime for the benthic plants. Nonetheless, there was significant seagrass growth in the shallow inshore waters, with an extensive meadow of Enhalus acoroides and Thalassia hemprichii. The smaller Halophila species (H. ovalis and H. beccarii) were reported to occur further along the shore near the mangroves; however we didn’t make it that far. After a little hesitation, the seagrass enthusiasts ventured out into the shallows, inspecting the seagrasses growing only a few tens of metres from the shore.
While the high nutrient levels in the water resulted in very turbid water conditions and high quantities of epiphytic and benthic macroalgal growth, particularly of Ulva, the seagrasses appeared reasonably healthy. In between the clumps of seagrasses were actively photosynthesizing benthic algal mats that were being grazed by gastropod snails, resulting in sandy patches on the seabed.
Following our wander through the seagrass meadows on Xincun Bay we reboarded the ferry to return to the mainland. The field trip provided a great opportunity to see the local seagrasses and provided a remarkable insight into the issues facing some of the seagrass meadows in southern China.
Back on the mainland a filling lunch was provided, that included a diverse and delicious variety of traditional Hainanese dishes, sustaining us for our return trip to Sanya. The bus ride provided an opportunity for some to snooze while others had plenty to discuss about the seagrass ecosystem we had just witnessed. For many it was a great opportunity to chat to new friends or catch up with friends from previous ISBW meetings.