Wednesday, June 8, 2016

Coral bleaching at Cyrene Reef

Most of the time,we will be exploring the seagrass and sandy areas of Cyrene Reef as they are thick with critters. On a super low tide, we decided to dedicate a slot for Cyrene Reef to look at the reef edge. However, it coincided with the coral bleaching period and it became a survey to monitor the extent of bleaching.

It's heartbreaking to see many of the corals bleaching. About 80% of the hard and soft corals appear stressed as they lose their coloration.

In case you are scratching your head wondering what is coral bleaching? Bleaching happens when corals (and also other cnidarians) lose the symbiotic algae in their bodies which help produce nutrients. It is the algae that give the animals their colour. Scientists think that most bleaching is caused by an increase in sea surface temperature. Find out more about bleaching in the Bleach Watch Singapore blog.

Here's another look from far on the bleached corals. They become more distinctive now.

And here's a closer look at both bleaching hard and soft corals.

This collage shows an assortment of different types of hard and soft corals affected by the bleaching event.

As the coral cover at Cyrene Reef is not thick, the bleaching looks sparse in photos like this. However, most of the corals are affected.

When they turn white, those commensals living in corals become evidently visible. Such as these orange Tiny colourful brittle stars (Ophiothela danae) on the Asparagus soft corals (Family Nephtheidae).

Here's more colourful tiny brittle stars on the soft corals.

As for the Cauliflower corals (Pocillopora sp.), one can easily spot the Red coral crab (Trapezia cymodoce) living among the branches.

The sea anemones are also affected by the bleaching event and they also lose their coloration or turn slightly purplish when stressed up.

The consolation would be that not all the corals are affected. Some of them still look healthy.

Here's a collage of the hard and soft corals that still look alright. Let's hope they stay ok.

One may wonder where did many of the Knobbly sea stars (Protoreaster nodosus) go to. On this trip, as I walked far to the other end, I realised they have moved to this corner of Cyrene. There are so so many of them!

A lovely surprise on this trip would be to find a juvenile Fluted giant clam (Tridacna squamosa)! It's been a while since we see them on Cyrene.

Jellyfish seems to be very common in this hot season and we see quite a number of them in our waters. And near some of them, you can find fish swimming around.

This was the fish that swam around the purple jellyfish.

Jonathan spotted this interesting moment of the Carpet eel blenny (Congrogadus subducens) snacking on a Diamond wrasse (Halichoeres dussumieri). It later swallowed the whole wrasse by gulping it down.

The team found several of the special Pentaceraster sea stars (Pentaceraster mammilatus) in different coloration. 

Shall end off this post with a photo of the beacon at the other end of Cyrene Reef.

More photos of the trip can be found here:

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