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**OUinLA** · 11-02-2005, 11:24 PM

Very interesting Gary, although, I don't fully understand what i'm seeing. Maybe i should read the full text but I wouldn't be surprised if I was just as much in the dark after reading, as I am now. Can you briefly describe what we are seeing and what the role of the CCA is (coraline)?

**Aged Salt** · 11-03-2005, 05:04 AM

Interesting article, Gary--apparently the bacterial biofilms provide the morphogens needed for coral chemoreceptor activation & metamorphosis? I'm with Madison here, tell us more

Thnx. Bob

**mesocosm** · 11-03-2005, 07:32 AM

Greetings All !

Originally posted by OUinLA

Very interesting Gary, although, I don't fully understand what i'm seeing. Maybe i should read the full text ...

Hehe ... yes .. I've usually found that reading an article helps me to understand it better ...

...

...

Originally posted by OUinLA

Can you briefly describe what we are seeing and what the role of the CCA is (coraline)?

Briefly? ... me? ... surely you jest ...

In all the discussions during the past few years regarding the role of biofilms in the ZEOvit methodology, did anyone ever post an image of what such a bacterial community might look like? I didn't remember any ... so I thought the micrograph might be cool.

Each of the frames has an associated ltter. Frames A through D show what these "shallow" and "deep" biofilms looked like at 4 and 8 weeks. Frames E and F show the biofilms on coralline algae, and G and H show the development a coral larva on coralline algae, and not on coralline algae, respectively.

As to the role of coralline algae ... "The primary source of chemical morphogens described for coral larvae are various species of nongeniculate calcareous coralline algae (CCA). These are thought to produce cell-wall-bound, high-molecular-mass polysaccharides that are recognized by chemoreceptors on the planula."

Originally posted by Aged Salt

Interesting article, Gary--apparently the bacterial biofilms provide the morphogens needed for coral chemoreceptor activation & metamorphosis?

That a biofilm has the potential to participate, "... in triggering the metamorphosis of a scleractinian coral" ... was news to me. I had always pictured the site attachment process for coral larvae to be fundamentally passive, but it turns out that, "Larvae of many coral species actively select a site of permanent attachment using external chemical cues that induce metamorphosis." It would seem that a biofilm can provide chemical cues.

Just trying to fill in the data set ...

**Ger** · 11-05-2005, 11:33 AM

That a biofilm has the potential to participate, "... in triggering the metamorphosis of a scleractinian coral" ... was news to me. I had always pictured the site attachment process for coral larvae to be fundamentally passive, but it turns out that, "Larvae of many coral species actively select a site of permanent attachment using external chemical cues that induce metamorphosis." It would seem that a biofilm can provide chemical cues.

Kind of makes sense.... "assures" the larvae that it has found an area with a high likelyhood of survival. If you were a larvae you'd "know" what type of environment you like.... "clean" water where certain algae thrives (like coralline) or more "turbid" water where other types of algae have taken over... (you don't want to be covered by THAT algae, or sand, or whatever).

**coralite** · 11-06-2005, 12:49 PM

I am gonna be lazy and just copy my answer from my marine ecology study guide. This is just a background into how the environment has an effect on every part of benthic larvae settling.

4.Be able to describe the steps that larvae of benthic species are recruited into and onto a suitable benthic habitat, including settlement, substrate selection, attachment and metamorphosis, and give several examples.

Larvae of benthic species have a internal cues when they reach a certain stage of development that signals for them to settle. This might include blocking the photopositive response which keeps them in the upper layers of the water column so that the larvae migrate to the bottom. Physical cues of their environment such as flow conditions, water temperature and salinity will guide them to the appropriate area and chemical cues of food sources and conspecifics will induce the actual touchdown with the bottom. Once the larvae are in contact with the bottom they may crawl around a little bit to find the right spot and once they settle they will metamorphose into their final adult form. Corals look for chemical cues from coraline algae and barnacles are attracted by aggregations of their species.

**Ger** · 11-06-2005, 03:38 PM

barnacles are attracted by aggregations of their species.

Similar to guys.... they are attracted to aggregations of the female species.

**coralite** · 11-06-2005, 05:06 PM

You are absolutely right gary,
Unlike many benthic animals who broadcast spawn, barnacles actually have intercourse and that is why many benthic ecologists claim that the barnacle penis is an organ of grand proportions. But the only barnacles I care about are those that live in corals and they no doubt have their own settling cues (aka chemical flypaper) that attracts them to settle on or very near a host coral.
Here is an awesome specimen of a blue barnacle species in a leptastrea coral, taken at IMAC this summer.

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Metamorphosis of a Scleractinian Coral in Response to Microbial Biofilms.

Metamorphosis of a Scleractinian Coral in Response to Microbial Biofilms.

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