Marine Biology: St John's Island

Again we had to wake up early for this trip to St John's Island. We had to reach school at 4.15 which is a far cry from 9.15 the previous week :( We were half-zombies in both the bus and the boat ride but luckily the boat ride this time was only half an hour as St John's Island is closer to the Singapore mainland.

It was past 5.30 by the time we reached St. John's island and by the time we changed into our booties and prepared for the intertidal walk, it was already 6. Sunrise was only until another 40 minutes so it was extremely dark and we had to use multiple torchlights to illuminate the path and slowly thread our way through the rocky environment. At one point, we even had to scale down a rocky slope to reach the shoreline area in pitch darkness if not for the torchlight ._. We were really scared something bad was going to happen given to slipperyness due to algae overgrowth but thakfully nothing did.

For this trip, our guides wanted to give us more hands on experience so we were given gloves and water containers to find and retrieve marine organisms that we come across on our own.

Our guides also did not want to talk much and let us do the explaining ourselves. We felt we did a pretty good job trying to explain the marine organisms under a rock for example such as their mode of feeding and reproduction by its appearance and structure. Many of these organisms clump together in a small group for survival purposes. As they say, united we stand, divided we fall.

St John Island is pretty different from our previous two visits to Pulau Semakau and Pulau Hantu. As this is a rocky shore, the organisms we come across will no doubt be slightly different. With the effect of the tides in a rocky shore, the sea brings plankton and broken organic matter in with each tide. The availability of light and nutrient levels means that producers such as algae can grow effectively which will benefit the food web. The rocky outposts also can provide an area of refuge for marine organisms.

Many marine organisms use shells, holdfasts or a thick mucous layer to provide stability against strong wave actions that can result in desiccation or dehydration especially during low tides. The crevices in the rocks in the shores can also contribute to being containers of pollution due to human action. As such there are many advantages and disadvantages of living in a rocky shore but the organisms here have adapted to this.