Archive for the Research Category

ICRS (Day 3)

Wednesday, July 9th, 2008

A view from the ICRS Fort Lauderdale… Cruise ships, smoke stacks, palm trees, cargo containers, jets, and blue skies… Welcome to Port Everglades.

Once again, an impressive number of topics relevant to reef aquarists on the third day of the International Coral Reef Symposium. To summarize:

In a lecture on the genetic diversity of Heliofungia actinoformis populations in Indonesia, I learned that the global trade in live corals is worth between 200-330 million US dollars annually (and no doubt increasing). This represents between 11-12 million corals exported each year. That’s a lot of coral…

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In an in-situ (lagoon based) coral aquaculture experiment in the Maldives, researchers concluded that the most efficient way to maximize the development of axial polyps (fast growing branch tip polyps) in Acropora muricata (a “staghorn” species) was to do the following:

  • Use basal fragments (mid-branch, not branch tips, i.e. broken on both ends) laid down horizontally on the grow-out tray (perpendicular to the water surface).
  • Induce injury (by scraping off sections of basal polyps) at several locations along the top of the fragment to encourage the development of axial polyps that will form new branches
  • The smallest fragment sizes in the experiment (3cm) maximized axial polyp formation. Productivity was increased by 75% by using three 3cm frags instead of one 9 cm frag.

It should be noted that the experiment took place in pristine water conditions, so survivability was nearly 100%. Algal overgrowth and disease was not an issue. I would expect that if this experiment took place in more nutrient laden water, that survivability would be reduced when inducing injury on such small fragments (3 cm). Nevertheless, I would have predicted the faster growth from branch tips rather than mid-section fragments, but in fact this sort of “pruning” clearly encourages the growth of multiple, fast-growing branches.

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There was another interesting lecture entitled “Morphological Dependance of the Variation in the Light Amplification Capacity of the Coral Skeleton” that focused on the ability of a coral’s aragonite skeleton to amplify light by scattering it over a wider surface area, and ultimately providing surrounding polyps with more available light for photosynthesis.

The researchers tested different skeletal morphologies (i.e. massive, branching, plating, etc), and discovered that there was a clear correlation in light scattering depending on the corals’ growth form. For instance, the encrusting coral Porites branneri was able to absorb four times as much light over the same surface area as that of a smooth sea grass blade. Of all the corals tested Echinopora horrida (a branching coral) absorbed the most amount of light, where as Caulastrea furcata ( phecelloid morphology i.e. polyps are seperated with no connecting tissue) absorbed the least. It should be noted that Acropora branching corals scattered light so well that their lab equipment could not properly calculate the efficiency of this scattering. They estimate that Acropora is capable of absorbing more than 10 times the amount of light than what would otherwise hit a flat, non-aragonite surface. To summarize, they conclude the efficiency of light absorbtion more or less follows this morphological pattern:

(least) Solitary polyp < Phaceloid < Massive < Plating < Branching (Most)

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A genetic analysis of the yellow tang (Zebrasoma flavescens) seemed to indicate the possibility that this species developed within the Hawaiian Archipelago (where it is common), and then more recently spreading south and west through the northern tropical/sub-tropical Pacific. Over this large geographic distance genetic variability was quite low, indicating wide larval dispersal carried by oceanic currents. Peculiarly, around the Big Island of Hawaii, up to four distinct genetic populations existed in rather close (but clearly separate) vicinities. It was posited that the yellow tang has not reached the Southern Indo-Pacific due to niche overlap and competition with the common scopas tang (Zebrasoma scopas). Where these two species occur at the same location, hybridization is common.

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I got to spend some time with Brian Plankis and Eric Borneman to discuss their Project DIBS and Reef Stewardship Foundation. I will do my best to highlight these endeavors in a separate post. In the meantime check out their websites, and sign-up with Project DIBS (Desirable invertebrate Breeding Society).

Zoanthids at the ICRS (Day 2)…

Tuesday, July 8th, 2008

One of the first presentations that I caught today at the ICRS focused on the genetic analysis of Indo-Pacific and Caribbean zoanthid species. The work was performed and presented by Dr. James Reimer, a zoanthid specialist at the University of the Ryukus in Japan. If you’ve ever spent any time on CoralPedia.com (formally Zoaid.com), you might be familiar with Dr. Reimer and his work. Take a look here to see his photo gallery…

For Indo-Pacific species he analyzed Zoanthus vietnamensis and Z. sansibaricus. For Caribbean species he analyzed Z. sociatus and Z. pulchellus. His findings revealed that Z. vietnamensis and Z. sociatus were genetically similar enough to be considered part of the same closely related clade (a taxonomic group with a common ancestor). Similarly, Z. sansibaricus and Z. pulchellus were shown to be grouped together in another clade. This suggests that at one time in the Earth’s history, these two pairs of zoanthid species were at one time the same species (Z. vietnamensis= Z. sociatus, Z. sansibaricus= Z. pulchellus). The separation of the species occurred when the isthmus of Panama closed about 3 million years ago.

Further genetic analysis of the Symbiodinium sp. (zooxanthellae) from Z. vietnamesis and Z. sociatus showed that these two species share identical symbiotic zooxanthellae, despite at least 3 million years of geographic isolation in different oceans. The same was true when he compared the zooxanthellae from Z. sansibaricus and Z. pulchellus. Dr. Reimer believes that the separation and development of the current species occurred about 6.5-7 million years ago.

Additionally, the two clades are similar enough with each other that genetic similarity suggests that all four current species shared a single common ancestor about 15 million years ago.

Zoanthus gigantus (aka Great Gatsby People Eater) collected by Coral Morphologic in the Florida Keys.

I asked Dr. Reimer if he had had a chance to compare the DNA from Caribbean and Pacific specimens of Zoanthus gigantus (known in the hobby as “People Eaters”). Unfortunately, he only has one sample of Caribbean Z. gigantus, and therefore hasn’t been able to do the appropriate analysis. To overcome this hurdle, we have offered to help supply him with these and other Caribbean zoanthids for future studies.

International Coral Reef Symposium (Day 1)

Monday, July 7th, 2008

Today began the first day of the 11th International Coral Reef Symposium (ICRS) in Fort Lauderdale, FL. These symposiums take place every four years (2004 was in Okinawa, 2000 was Bali), so we were incredibly lucky to have this world-class scientific event taking place right up the road from Miami. I will do my best to summarize the facts and insights that I think reef aquarists would find most interesting…

- The fungiid coral Ctenactis echinata and to a lesser extent Fungia repanda can engage in hermaphodism (sex change) over the course of their lifespans. Some can even change sex more than once (m->f->m). Apparently the smaller, younger individuals are more likely to be male, and as they get larger and can afford to invest more energy into egg production, they switch to female. At medium sizes, they can change sexes on alternate spawning years. Spawning takes place at 8:45 pm 5 nights after the full moon in July (at least in Japan where the research took place).

- While much attention has been made over the precipitous decline of Diadema urchins on Caribbean reefs, and the resulting overgrowth of macroalgae in the absence of said urchins, a study done in Panama suggests that urchins of the genus Echinometra are at least comparably effective at macroalgae removal as Diadema. Overgrowth from macroalgae is considered a primary roadblock to proper coral larvae settlement, and therefore herbivores like urchins are necessary to keep the coral reef ecosystem in balance.

- It was discovered by accident during an experiment on coral larvae settlement that the larvae of Porites asteroides showed a decided preference for settlement on fluorescent orange/red plastic cable ties. In fact, they settled significantly more so on these cable ties than on the expected preferred substrate of crustose coralline algae (similarly pink/purple in color). The researchers then investigated the role of the chemical rhodopsin in the selection of substrate. Rhodopsin is the chemical found in the human eye that absorbs blue-green light, but appears purple. Coral larvae apparently also contain this chemical and can use it to sense their preferred settlement substrate, crustose coralline algae, and the availability of light. Experiments using other fluorescent colored cable ties (green/blue) did not significantly attract the larvae to settle. This seems like an interesting tid-bit of information that pioneering aquarists could find useful in the event of sexual reproduction of their corals.

- The bubble tip anemone (Entacmea quadricolor) was studied by researchers in Australia who investigated its sexual reproductive habits in the wild. Apparently, this species, like the Fungiids mentioned above, is capable of sex change. Typically, the males were smaller, and the females larger, with an average sex ratio in the wild of 1.6 females to every 1 male. This lopsided distribution was attributed to the propensity of the larger females to more often engage in asexual division (hence more females). Spawning by males took place once a year, while females sometimes mated more than once, usually several days after the full moons in January through March.

Literally, there are scores of these short 12 minute lectures each day, with many taking place simultaneously. This makes it difficult to catch every interesting topic. There are also hundreds more poster presentations in the exhibition hall. Aquarium author and coral expert Eric Borneman has several of these posters on display that I hope to catch in the coming days. I’ll keep the blog updated. Sorry for the lack of photos… Camera batteries died, and back up batteries were similarly DOA…Doh! I’ll be sure to take more tomorrow.

Microscopic Sea Battle

Monday, April 28th, 2008

Our good friend Akihiro Shiroza, a marine biologist at NOAA here in Miami, spends most of his working hours looking at the planktonic larvae of fish, corals, crustaceans, etc., under microscope. He was kind enough to share photos of some of the cool plankton he encounters. It appears here that he discovered a squid vs. shrimp battle of micro-mythological proportions. He used a polarizing filter to get the cool rainbow background effect. We’ll look forward to more of Aki’s photographic finds here in the future.

Corallimorph Archetype

Friday, April 25th, 2008

A diagram of the archetypal, deep-water, and rarely collected corallimorph Corallimorphus ingens taken from Zoologishe Verhandelingen ” Corallimorpharia collected during the CANCAP expeditions (1976-1986) in the south-eastern part of the North Atlantic” J.C. den Hartog, O. cana, and A. Brito. 1993

90 Gallon Caribbean Reef Biotope at the University of Miami

Friday, March 21st, 2008

For the past several months we have been working in conjunction with the marine science laboratory at the University of Miami and the UM Aquarium Club (UMAC) in the development of a 90-gallon Caribbean reef biotope in the marine science laboratory. The backstory as to how and why we got involved in this project is more or less as follows…

University of Miami MSC 90-Gallon around it’s heyday (2005-ish)
At that time, a mixed species reef aquarium.

Click to read “Part 1 of 90 Gallon Caribbean reef Biotope @ the University of Miami”…