International Coral Reef Symposium (Day 1)
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.