Spotlight on Sponges

January 9th, 2009 | 3 Comments
About, Sponges

The following is a guest blog from Dr. Alan Duckworth, Blue Ocean Institute’s Research Scientist.

Days 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 University 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.

 During the next few years, Amber 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, and they filter the water by removing bacteria and small particles, keeping the water crystal clear.

Yellow Tube Sponge - Aplysina fistularis

Yellow Tube Sponge - Aplysina fistularis

Amber Stubler photographing a large sponge

Amber Stubler photographing a large sponge

 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, a 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 colors.  Gorgonians, related to hard corals, are also common, particularly in shallower water (less than 40 ft).

 

A shallow water field of Gorgonians and Algae

A shallow water field of Gorgonians and Algae

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!

 Days 3 and 4

 After a few days in the field you get into a daily rhythm of research. You know when mealtimes 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.

Soldier fish against a backdrop of sponge and algae

Soldier fish against a backdrop of sponge and algae

 It’s worthwhile, however, because the diving is fantastic.  Underwater visibility exceeds 50 feet, the water is warm so a wetsuit is not required, and sponges and soft corals are generally numerous and beautiful.  

Sponges and sea anemones

Sponges and sea anemones

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 80s and 90s.  Once the algal-grazing sea urchins disappeared, algae populations grew unchecked, smothering corals and killing them.  Thankfully, there are signs of recovery.  At shallow depths, sea urchins are now common, algae are sparse, and corals are growing back.

Sea urchins and healthy coral

Sea urchins and healthy coral

 Second, there are very few medium to large fish. Most fish swimming past your mask are less than 1 foot in length.  This is likely the result of overfishing, particularly from the numerous fish-pots that dot the coastal waters.  

Fish pot on sand

Fish pot on sand

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.

 Cheers, Alan

3 Responses to “Spotlight on Sponges”

  1. Dwayne says:

    Ineteresting reading. You call it over fishing in your writeup but the locals have been their for centuries and as such have been finishing for survival. Has this been the case for centuries that there have been no large fish or is it because they have become more commercial in their fishing practicies?

  2. Batter says:

    Thank you for the sensible critique. Me and my neighbor were just preparing to perform some research relating to this. We got a grab a book from our local library but I think I learned more out of this post. I’m very glad to view such great information being shared freely available.

  3. carlsafina says:

    Diggings in Indian middens show that as soon as people got to those islands, the size and type of fish they were eating started changing, and its fish got smaller over time because of pressure applied by people fishing. The greatly increased human populations and commercial fishing of the last few decades greatly accelerated this trend and, long story short, it helped lead to the present situation where corals were replaced by algae, in large part because the grazing fish are too few to suppress the algae that comes in after corals are killed by diseases or storms. Without those grazers, algae thrive and corals can’t regain their foothold. – Carl Safina replying in Alan Duckworth’s absence.

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