Keelung Chaoching Marine Citizen Scientists — What's Covered in the 2023 Advanced Underwater Training Course?

Last year, I managed to snag a spot in the Keelung Marine Citizen Scientist "Basic Underwater Training" course before it sold out in seconds. Everyone came away with a wealth of knowledge about different species and the key points for photographing and identifying them — so much so that when registrations opened for this year's "Advanced Underwater Training" course, the spots were gone almost instantly. Fortunately… I still managed to get in.

This course is designed to lead divers who have already completed the introductory level through indicator-species surveys so they can better understand underwater ecosystems — and ultimately help recreational divers contribute to academic research and marine conservation efforts.

The course is built around three main pillars. The first was a lecture by instructor WOX on the significance of indicator species and the key points of conducting surveys, covering two broad categories: invertebrates and fish.

What Are the Indicator Species?

Indicator invertebrates include mantis shrimp, lobster, slipper lobster, diadema sea urchins, crown-of-thorns sea stars, pencil sea urchins, rock-boring sea urchins, sea cucumber, triton's trumpet, top shells, turban shells, and giant clams.

Among these, diadema sea urchins and crown-of-thorns sea stars are considered harmful because they prey on coral. Lobster and slipper lobster, with their high commercial value, can serve as indicators of overfishing. Pencil sea urchins, rock-boring sea urchins, top shells, and turban shells graze on algae and are therefore considered beneficial to coral reef growth. Sea cucumber and triton's trumpet help keep the substrate clean — triton's trumpet is especially important for coral reef conservation because it can consume crown-of-thorns sea stars. The strikingly beautiful giant clam can build reef structures, help purify water quality, and create habitat for small organisms.

Unfortunately, almost all of these coral-friendly species have high commercial value, making them popular targets for human harvesting. This means that beyond being indicators of reef health, they are also nearly universal markers of overfishing.

Indicator fish species include moray eel, Grouper, humpback grouper, sweetlips, snapper, humphead wrasse, butterflyfish, and parrotfish. With the exception of butterflyfish and parrotfish, all of these are apex predators. Their presence indicates that an ecosystem is rich enough — with sufficient numbers of mid- and lower-level organisms — to sustain them.

Butterflyfish depend directly on coral reefs for their survival and are therefore reliable indicators of reef health. Parrotfish help remove algae and break down substrate, making them key fish for sustaining coral reefs. Among them, the bumphead parrotfish is especially prized, as it is simultaneously an apex predator and a major indicator of overall ecosystem health. However, due to overfishing, these species tend to show a trend toward smaller body sizes. Their abundance and size are useful for assessing whether a given area is being overfished — and their presence is itself an important indicator of coral reef vitality.

Instructor WOX noted that beyond these universal indicator species, individual regions may also designate certain specific organisms as local indicators based on factors such as their influence on substrate succession or their role as proxies for fishing pressure.

How Is an Underwater Survey Conducted?

The second major pillar of the course was a session led by instructor Ah-Xian on how to carry out an underwater survey. The steps are as follows:

1. A professional diver first lays out a 30-metre transect line underwater using a measuring tape.
2. Teams of four are formed: one person conducts the fish survey, one conducts the benthic organism survey, and the remaining two work together with a 25-grid quadrat frame and a camera — one placing the frame, one photographing it — along the transect line.
3. Teams begin moving one minute after the professional diver has finished laying the measuring tape. Everyone proceeds along the tape in sequence, surveying a 2-foot band on either side of the line.
4. The departure order is: fish surveyor first, then the benthic organism surveyor, and finally the substrate surveyor. This prevents the sand and sediment stirred up when the substrate surveyor places the 25-grid quadrat frame from affecting the observations of those who follow.
5. After surfacing, participants fill out a "Survey Record Form" documenting the day's weather, tidal conditions, dive depth, and recorded species, completing the record for that session.

Instructor Ah-Xian reminded everyone of several important points to keep in mind during the survey:

1. The fish surveyor must be careful not to double-count. When encountering a large school of fish, a quick count of 10 individuals can serve as a reference for estimating the total number, and the result should be noted on an underwater slate.
2. When the benthic organism surveyor encounters gastropods (snails), remember to flip them over and photograph the aperture (opening) for accurate identification.
3. The substrate surveyor must ensure the quadrat frame is laid flat before taking a photo so that it can be properly analysed afterward. The contents are then categorised by substrate type — rock, gravel, or fine sand — and by vegetation type: green algae, red algae, brown algae, coral, or sponge.

My write-up may look neat and orderly, but in practice there was a certain amount of pre-dive confusion as everyone wrestled with different mental images of how it would all work. Fortunately, instructor Ah-Xian patiently clarified everything, and the group was eventually able to enter the water in an organised fashion for the highlight activity: the underwater survey itself. That day, 12 participants were divided into 3 groups of 4, each covering a separate transect.

The Underwater Survey Begins!

The underwater survey felt like it went quite smoothly from my end. Having the transect line to follow meant navigation was never an issue, and a dive instructor patrolled back and forth along the line throughout. With everyone's diving well under control, the whole dive was safe and calm, allowing each person to focus on their survey work.

But once we surfaced, everyone had their own little story to tell. The participant doing the fish survey said she was juggling a GoPro, filming and counting simultaneously, scanning a full 360 degrees, and trying not to double-count — she said it was exhausting!

I was responsible for recording benthic organisms. When I first descended, I couldn't find a single snail or sea urchin, which was a little embarrassing — until I remembered that it was daytime and they would likely be tucked away in the rock faces. After that, I slowly tracked them down one by one and logged them. Instructor WOX also reminded the participants photographing benthic organisms that after flipping a snail over to photograph its aperture, you need to turn it back! He spotted a snail that had been left upside down and was unable to right itself, leaving its soft body exposed and nearly getting it pecked at by a fish. Fortunately, he caught it in time and flipped it back over, saving the little creature's life.

The substrate team — two people working together for the first time — had their own challenge. The protocol called for shooting at every 5 metres: one shot from the transect line, then one flat quadrat photo to the left and one to the right. Then repeat at 10 metres, 15 metres, and so on along the 30-metre transect. Somehow, they ended up shooting all the way out to 50 metres.

Instructor WOX also admitted that he had deliberately run the transect line through a particularly uneven section of the seafloor to test how the substrate team would manage to take level photos without moving the line.

When reviewing the recorded photos afterward, the substrate team laughed that while they had passed that challenge, a small fish had photobombed the bottom-right corner of one shot, nearly rendering it unusable.

Instructor WOX explained that substrate photos must not only be level and free of reflections (which is why a strobe cannot be used), but must also be free of obstructions — including fish — as these interfere with analysis. Fortunately, the fish in question was small enough that the impact was minimal.

The most entertaining part of the debrief was when instructor WOX used photos taken by participants to share fascinating bits of natural history: a crab hiding inside a sea urchin's anus, and a baby egg cowrie mimicking a flatworm.

The most important lesson was learning how to make evidence-based assessments of an area's ecological health using indicator species — and understanding how to reduce behaviours that harm marine ecosystems. For example: stop eating rock-boring sea urchins and parrotfish! Let them do their job of removing algae, so our coral reefs can recover.

After the course, my greatest hope is that we can put what we learned in class to practical use — so that those of us who started out as recreational divers can contribute to academic research and marine conservation, and leave a living, enduring hope for the deep blue we love so much.

Further reading:

• Marine Citizen Scientist Species Database
• 2023 Keelung Chaoching Conservation Area — Marine Citizen Scientist Species Database
• Marine Citizen Scientists Using Underwater Photography to Support Ocean Conservation and Fundamental Research
• Wild Feng's World of the Curious