Blue Ocean Institute

Jun 8th
2009

Sexy Sponges

The following article was originally posted on Carl Safina’s blog and describes my field trip to Jamaica in Jan 2009

Day 1 and 2. On Monday I left the cold climes of New York for the considerably warmer and more pleasant tropical weather of Jamaica. I’m here in Jamaica to co-supervise Amber Stubler, a Stony Brook graduate student, with her project examining the effect of coastal development, such as large resorts and hotels, on coral reef life. Tourism is the life-blood of Jamaica, as it is throughout much of the Caribbean, and it is vital that we scientifically determine what effect it may have on marine animals and plants.

Amber Stubler photographing sponges

Amber Stubler photographing sponges

During the next few years, she will investigate the effect of this development on the recruitment, growth and distribution of coral reef organisms. Although a great range of benthic coral life will be examined, this project will focus on sponges, a group of fascinating and important animals found in all seas. “Coral reef” may be the type of habitat but in much of the Caribbean, including Jamaica, sponges are the most conspicuous and most common animal. They are also essential for the survival of coral reefs. Sponges provide food and refuge for many fish and turtles, plus filter the water removing bacteria and small particles, keeping the water crystal clear.

Bright yellow tube sponge Aplysina fistularis

Bright yellow tube sponge Aplysina fistularis

For the next two weeks, we are based at the Discovery Bay Marine Laboratory, situated next to a beautiful coral reef. The lab is collection of buildings providing accommodation, administration services, laboratories, dive area…and most importantly after a busy day, a kitchen where Jamaica ladies prepare amazing feasts.

Discovery Bay Marine Laboratory

Discovery Bay Marine Laboratory

Tuesday was our first diving day, spent identifying the best sites to survey and determining the best sponge species to study. The local reefs are rich in sponges, of differing sizes, shapes and colours. Gorgonians, related to hard corals, are also common, particularly in shallower water (less than 40 ft). Hard corals are not so obvious, which is probably a result of the many environmental challenges that have hit the Caribbean in the last 30 years. Even so, the diving is fantastic and the water is warm, around 25 C (77 F)! So to all who are suffering the icy weather throughout much of North America, the only ice I see in Jamaica are the ones floating around in my drink!

A shallow water field of gorgonians and algae

A shallow water field of gorgonians and algae

Day 3 and 4

After a few days in the field you get into a daily rhythm of research. You know when meal-times are (7:30, 12:30 and 6:30), you know the layout of the research station and who to ask for equipment, you get a feel of weather cycles and you know where and when you should dive. Situated on the northern side of Jamaica, the wind is slight and the seas are calm until late morning, when a breezy north-easter kicks in making long boat trips rather uncomfortable. Therefore, you plan to dive mostly in the morning, even if that means you are entering the briny depths when others are drinking their first cup of coffee.

Dive gear

Dive gear

It’s worthwhile, however, because the diving is fantastic. Underwater visibility exceeds 50 ft, the water is warm so a wetsuit is not required, and sponges and soft corals are generally numerous and beautiful. After a few dives in Jamaica, however, two things become glaringly obvious compared to other coral reef systems such as on the Great Barrier Reef.

First, much of the coral reef is devoid of living coral. This probably results from a massive die-back of sea urchins in the 80 and 90’s. Once the algal-grazing sea urchins disappeared, algae populations grew unchecked smothering corals and killing them. Thankfully, there are signs of recovering. At shallow depths, sea urchins are now common, algae are sparse and corals are growing back.

Second, there are very few medium to large fish. Most fish one sees swimming past your mask are less than 1 ft in length. This is likely the result of overfishing, particularly from the numerous fish-pots that dot the coastal waters. Made from wood and chicken-wire and baited with coconuts and fruit they are efficient at catching fish. However, when a fisherman needs to catch these fish to put food on the table for his family it is not possible to be judgmental about fishing practices.

Fish-pot on sand at 50 ft

Fish-pot on sand at 50 ft

Days 5-8

The past few days have been mostly spent attaching settlement plates to the reef. Each plate, 11 x 11 cm in size, is made of terracotta, which is a good substitute for coral substrate. This will allow us to measure the number and type of sessile organisms (e.g. sponge, coral, and algae) that settle and recruit onto Jamaican reefs. First, two small holes are drilled into the reef using an air drill run off a large SCUBA tank. Next the stainless steel base plate is secured to the reef, using two “xmas tree” bolts. Finally, a numbered settlement plate is bolted onto the base plate. The settlement plate rests about 1 cm off the substrate so organisms can settle on the top and bottom. Most animals settle on the bottom side, away from light and predators.

Settlement plate, side on showing base plate

Settlement plate, side on showing base plate

Although it’s heavy work, drilling holes is a lot of fun. We drill holes into dead coral only so there is minimal impact to the reef. However, some dead coral is so dense that only a few holes can be drilled off one tank, which means that you need to swim back to the boat several times to swap tanks to finish the job. Afterwards, small fish swarm around inspecting the work, trying to find any worms flushed from the dead coral.

Drilling holes

Drilling holes

We have attached settlement plates at 30 and 60 ft in one impact location (next to several resorts), and two control or non-impacted locations. Plates will be photographed, examined and replaced every 6 months for 2 years. This experiment will help determine what effect coastal development has on the recruitment of sessile organisms onto coral reefs.

At each depth and location we also deploy settlement traps. These will record the amount, type and size of particles (e.g. sand, terrestrial mud) that wash off from the surrounding land. These are left out for 1 week only.

Deploying sediment traps

Deploying sediment traps

All going well we should knock it off in one more day. The work is very enjoyable but tiring. Generally we leave at 7 am and return at 1 pm. If the weather holds we head out for another dive in the afternoon. In between we clean gear, fill tanks, get equipment organized, brush-up on sponge identifications, plan for the next day, and….eat.

Days 9-12

The settlement plate experiment is now finished, with plates anchored to the reef at two depths in an impact and two control locations. Now we wait 6 months to see what marine organisms have settled and are growing on the plates. To get meaningful data that encompasses any seasonal and annual effects, this experiment will run for 2 years. Ideally, the experiment should last for another year or more, but research funding always dictates what marine science you can do.

The next experiment is a growth study, where we tag several sponges of various species at the three locations to determine what effect, if any, coastal development has on sponge growth rates. All up, 180 sponges will be monitored over time, which means a lot of swimming to find suitable sponges to tag. The tag is nailed onto dead coral next to the sponge, so it does not interfere with its growth. Each sponge is then measured and photographed. Diving days for the growth study are similar to the settlement plate experiment, but no heavy drilling gear is needed.

Measuring sponges

Measuring sponges

This field trip is rapidly coming to a close, with only one full day left. Before I came down I had heard of the great diving in Jamaica, and it’s true. The water is clear, warm and inviting. The local reefs are a sponge mecca, encompassing all different shapes, sizes and colors. The lack of medium and large coral reef fish is a concern, but it is not likely to change anytime soon.

Eel being defensive

Eel being defensive

Much of the success of this field trip is due to the friendly and helpful staff of the Discovery Bay Marine Lab, who I thank greatly. Lastly, I leave you with a series of photos, showing some of the visual highlights from Jamaica.

Ballonfish hiding

Ballonfish hiding

Brown tube sponge

Brown tube sponge

Flamingo tongue on gorgonian

Flamingo tongue on gorgonian

Sponges

Sponges

Moonrise over Discovery Bay

Moonrise over Discovery Bay

cheers, Alan

Comments:  1

Posted in:   Climate, Research

1 Comment

  • thanks for info.!..:D

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