Crown-of-Thorns Seastar: threatens Japanese coral reefs

A follow up to my coral reef posting of last Monday, The Japan Times Online reported an increase at the coral reefs of Shirahama in the number of crown-of-thorns seastars, a species of seastar that feeds - and feeds ravenously - on coral.

Shirahama is located on the western Kii Peninsula just below the middle of Japan. Normally, the crown-of-thorns' range would be held in check by its preference for warmer tropical temperatures where, within a healthy reef ecosystem, it is held in balance as a predator by virtue of the dominance of coral. But the temperatures have been increasing and, along with human development (eutrophication) that has increased certain nutrient levels which weaken the coral, this has allowed the crown-of-thorns to expand its range and explode in numbers.

Unfortunately, the only immediate solution to the problem is a controlled eradication of the seastar. A small group of local divers have been enlisted in this effort which could carry on for several years. Care must be taken as the crown-of-thorns is covered on the outside with many spines (hence its name) that are actually sheaths for sharp poisonous needles.

"'If we keep removing (the starfish) in limited areas on a regular basis, there should be some effect,' said Katsuyuki Nakaya, 53, who runs a shop catering to divers and chairs an environmentalist group based in the city of Wakayama."

I have experienced the effect of the seastar's defensive weapons firsthand. When I was a novice diver, a came across my first crown-of-thorns in Hawaii. Fascinated with this ornate creature, I carefully turned it over to examine its underside and when I placed it back on the reef, I noticed a countless number of green threads streaming from the palm of my hand. Odd, I thought, until I realized the green color was blood having lost its red hue in the ocean depths. For the rest of the day my hand tingled as a subtle reminder: look but don't touch.

Read online article.

And the meek (or microscopic) shall inherit the earth

Discussions of climate change often focus on the big events that can catch the attention of the public - hurricanes, fires and flooding, vast sea melts, etc. But what can be most alarming are the subtle, microscopic changes that can have enormous consequences.

I was reading the latest Marine Science Review available from Seaweb.org (No. 267 - Pathogens, disease, and die-offs). It covers everything from epizootic shell disease in lobsters to wasting disease in burrowing starfish, and much more. Many of these events are isolated or cyclical outbreaks, but increases in water temperature is becoming more and more of a potential factor.

Increases in water temperature - even very small changes - can produce two negative effects: an increase in bacteria and viral microorganisms, and a weakening of the immune system of many aquatic life forms. Will Nature adjust to these changes? Most likely, but at what cost to various species?

To borrow the Biblical phrase, the meek shall inherit the earth. But it may not be the banner-waving, peacenik; it may be something smaller than the head of a pin - meek but deadly. Another important aspect of climate change that has to be considered.