Bubbles

Yes it seems that someone with less brains than a barnacle moved my thread pertaining to using bubbles to prevent barnacles to a thread named "Barnacle Prevention".

Well, we in the boating world realise that there are several methods to prevent barnacles from forming on a hull, be it anti fouling, electrolysis, or using a blanket under the boat to prevent crustacians from forming.

So, I'll try again. This thread is dedicated to investigating the use of bubbles to prevent barnacles from forming on the hull of a boat.

Get it! BUBBLES - BUBBLES - BUBBLES aparently using capitals is equal to shouting. If shouting is what I need to get through, then shout I will.

I do apologise to those who posted on my original thread, but it was not I who attached barnacles to it.

However I have thought to expand this to compressed air. As DTK I think, I get confused with a German motorbike who stated that it would agitate the water which would prevent the crustacians from forming, the exact reason for my friends suggestion that bubbles might work.

I will have to investigate barnacles, some Googling maybe to find out what prevents these little creatures from forming.

Meanwhile if anybody has any suggestions about how bubbles might work, bubbles, not anti fouling etc. etc. feel free to post.

Humour is always accepted, even if you leave out the u.

Love you all. exceptions apply. (that was the humour) I think.

 

Not correct, see . . . . . .

The bubbles are for barnacle prevention, right . . ? ? - And you clearly stated you couldn't find a thread about it....

Cheers,
Angel

 

Oh that's strange . . . . .

Cheers,
Angel

 

I am sorry for the misstep Poida. A descriptive title is of great help, as your original thread was titled simply "barnacles", you said you had searched unsuccessfully for "barnacles" leading Angelique and myself to believe you were looking for a more general discussion, and when Angelique suggested merging threads, I did not see any objection or any clarification in your subsequent post in that thread.

I am clear now that this new thread is specifically about:
Bubbles to prevent barnacles from forming on the hull of a boat
and not any other aspect of barnicle prevention or barnacles.

 

Let's not lose our sense of hmour.

 

Take a deep breath Poida, try not to get so stressed all the time

Intertidal zones on rocky exposed headlands are littered with barnacles around here, the water is almost always agitated and full of bubbles. In this neck of the woods mussels and oysters are more of a problem than Barnacles and they like bubbles and turbulence too.

 

Yes Mike I have been reading up on barnacles and agitated water doesn't seem to bother them once they have attached themselves to rocks and can live out of the water for quite a few hours during low tide. However I think that once they have been washed into an area they would have to wait for the turbulance to subside to cement themselves to rocks.

Apparently barnacles have penises 8 times the length of their body, which is another reason to hate them.

I am now considering air driven whip hoses as used in pools to sweep the hull of the boats to prevent them from landing. They like to live in clusters, so preventing a cluster from starting is half the battle.

The only problem with using whip hoses is the little buggers will be trying to have sex with them.

 

I've seen just about every contrivance, wonder chemical and creative solution you could dream of. I've been involved in trials of bizarre coatings, even horseradish sauce, ultrasonics and even a trial of a small robot wandering around scrubbing the hull. That didn't work very well and an octopus got tangled up in it once either trying to eat it or mate with it !

 

Some of my course work dealt with the critters who buy properties along the shoreline.
It appears the intertidal zone is some of the most valuable real estate around and competition is keen for each sq cm.

Bubbles sound like a nice feature to bring in even more inhabitants who might of passed on the relatively toxic boundary layer just over the hulls surface.
Water agitation (bubbles), may well help to attract barnacles as they are stationary creatures who rely on water movement to bring in their lunch.

There are reams of research papers on the topic of zone colonization by the denizens of the fouling communities.
It appears for decades scantily clad undergrads have been wading around in tide pools peering under rocks...
The very thought brightens the imagination and suggest some field research on the topic may be in order.

 

bntii, thanks for your input.

Barnacles rely on current for their food, they also rely on current to move when in a planktonic (I'm not sure if that is a real word, but I reckon it sounds good) state to colonise other areas.

But I am of the opinion that they require calm conditions to actually attach to a suraface. Continual agitation may mean that the barnacle when small would hit the stream of bubbles which would force them up and away from the hull.

I have yet to find any reference to the minimum velocity of water that they can settle in. It appears that the cement that they use sets in about 5 minutes and I have seen the results of hardness tests done on the cement.

Of course the reason nobody is really interested in this is because only penned boats with a power supply could use it which equates to minimal sales.

 

Hi poida

I was sort of joking around above but I did write a paper or two on fouling communities (not published- in course work), and had to review quite a few of the research papers on the topic.
One of the things which impressed me was the zone specificity of each organism and how the composition of the community would alter across the intertidal from wet dry tidal to the always submerged regions. Agitation as Mike mentioned is one of the many features of the environment as organisms become specialized to each niche across the range of conditions.

I would start with a search like this:

http://scholar.google.com/scholar?q...ture&hl=en&btnG=Search&as_sdt=1,21&as_sdtp=on

Or this:

http://scholar.google.com/scholar?s...ommunities flow recruitment&hl=en&as_sdt=0,21

Pick up a paper like this:

http://www.sciencedirect.com/science/article/pii/002209819490006X

or this:

http://www.springerlink.com/content/m8134537532l762j/

Or this one of flow characteristics:

http://www.esajournals.org/doi/abs/10.1890/0012-9658(1998)079[1395:FDVIIC]2.0.CO;2

This one may be starting to be specifically what you are asking about:

LINKING LARVAL SUPPLY TO RECRUITMENT: FLOW-MEDIATED CONTROL OF INITIAL ADHESION OF BARNACLE LARVAE

"Settlement rate was highly correlated to contact rate, and the proportion of settling larvae increased with established recruit density. In contrast to model predictions, contact rate was negatively correlated with local flow speed, which explained 33% of total variation. This correlation was maintained through settlement and recruitment suggesting that flow-mediated initial contact is an important link between larval supply and recruitment. No evidence from field studies indicated behavioral responses by larvae to flow although observations in a laboratory flume suggested active rejection of potential settlement sites at increasing flow speeds. It is suggested that initial adhesion is limited by flow speed through drag and lift forces acting on larvae. A conceptual model of mechanisms controlling the transfer of planktonic larvae to recruited benthic individuals is proposed."
http://www.esajournals.org/doi/abs/10.1890/03-0565

Read the papers (or others), and select from the citations towards papers which are closer to the subject area of interest for you..

It really is a fascinating region (the intertidal) and I find myself peering off docks where ever I am to see what is up with our invertebrate friends making a living on the piles just below the surface.

 

Has anyone ever studied the mechanisum of attachement? I have often wondered if producing a micro polished surface would keep them from attaching at all. Coating and polishing a hull to a micro finish might be a lot of work, but if it saves scraping barnicles it might be worth the effort. Perhaps not worth it on very large vessels, but on private yachts it might be viable.

Or do the larvae use some kind of sticky adhesive to bond to the surface? If so perhaps some kind of incompatible surface tension or charge can be applied, like how many sticky substances will roll off of wax paper or polyethylene because of the surface charge.

What is the mechanism that barnacles use to attach themselves to our boats?

 

Last spring I coated my boat's hull with an expensive sky blue Italian anti-fouling instead of the usual copper paint. The reason was the boat in the berth next to mine: it was impeccably clean while my boat looked like a vegetable garden.

Now, at the end of the season, the hull is still clean except for some algae around the waterline that can be wiped away with a sponge. But for some reason I don't yet understand, barnacles have colonized all metal surfaces like rudders, props and stern tubes. All of these were painted with the same anti-fouling.

The metal parts are stainless and bronze, all bonded to DC ground and protected by two zinc electrodes. Two stainless tubes that support a submerged platform are not connected to ground, they are virtually ignored by the barnacle larvae !!

 

Petros, they use a secretion that sets like concrete, I've seen the results of hardness tests and it's very hard, I didn't note the exact figures because it was not the info I was after. People have tried extracting it to use as a glue but it is rock hard in 5 minutes and of course that is underwater so the potential to harness the adhesive is huge.

But extracting it and preventing it from hardening and then getting it to harden when you want it is proving to be difficult.

btii - thanks heaps for the info I'll sift through it later, but so far it seems that preventing colonisation of barnacles is best prevented by providing an environment to which they can't cling to a surface long enough to attach.

CDK I am only guessing at this but the larvae needs to be trapped in a stick so the side of your boat is too smooth with the coating on but the prop has a boss and other bits of mechanical stuff (technical term) that could retard a barno's travels long enough to attach.

I find it funny when you read information about barnos colonating one area in preference to another. It's like the guys are calling out hey! come over here, come and join us.

It seems to me that barno larvae is tossed around by the current and gets trapped so it can attach. Even if one barno can get itself attached it makes a good trap for others. So obviously barnos won't prefer a current colony it's just where they get stuck.

It would be interesting to see the growth of barnos in relation to the boat's penned position.

I would imagine that penning it in line with the current would result in less barno attachment than penning it side on so the barnos get pushed against the side of the boat.

 

Analysis of behavioural rejection of micro-textured surfaces and implications for recruitment by the barnacle Balanus improvisus

"Experiments performed in the field and in the laboratory show that the barnacle, Balanus improvisus, preferentially settles on smooth surfaces. Settlement and recruitment of B. improvisus was evaluated on micro-textured surfaces with scales of surface texture ranging from 1 to 100 μm in profile heights. Surface texture with profile heights within a topographic range of 30–45 μm reduced settlement and recruitment by 92% as compared to smooth surfaces. The reduction in recruitment on micro-textured surfaces is best explained by behavioural responses to surface topography. Behavioural experiments show that cyprids have a higher propensity for smooth surfaces than for micro-textured surfaces. Cyprids spend more time exploring smooth surfaces and more time swimming when exposed to micro-textured surfaces. Micro-textured surfaces are more often rejected by cyprids after exploration than smooth surfaces. It is suggested that some scales of surface texture could be exploited to improve future anti-fouling techniques in geographical areas where Balanus improvisus is a severe fouling problem."
http://www.sciencedirect.com/science/article/pii/S0022098100002100

Reduction of barnacle recruitment on micro-textured surfaces : Analysis of effective topographic characteristics and evaluation of skin friction

"This study investigates five designed micro-textured surfaces and their effects on barnacle fouling and hydrodynamic drag. Three of the micro-textures were developed in the present study and evaluated together with two commercial riblet films. All micro-structures were arranged as longitudinal grooves with different profile depths, widths and angles of inclination. In field tests the recruitment of the barnacle Balanus improvisus on micro-textured surfaces and smooth controls was evaluated. All micro-textured surfaces reduced recruitment, and the most efficient texture reduced recruitment by 98%. For some micro-textures the reduction of recruitment declined as settlement intensity increased."
http://cat.inist.fr/?aModele=afficheN&cpsidt=886669

BARNACLE LARVAE ACTIVELY SELECT FLOW ENVIRONMENTS SUPPORTING POST-SETTLEMENT GROWTH AND SURVIVAL

"Many marine dispersive propagules select specific settlement sites based on a range of environmental cues. However, the link between larval choice and post-settlement growth and survival is still poorly understood. Here we show that cypris larvae of the barnacle Balanus improvisus actively reject surfaces exposed to local flow speeds exceeding 5–10 cm/s. Field experiments show that post-settlement growth and survival decline in free-stream flows above 15 cm/s. Moreover, studies in flume flow at local speeds exceeding 10 cm/s reveal that early juveniles show reduced feeding rates caused by deformation of the cirral fan, reduced retention efficiency, and a decrease in time spent feeding. We conclude that cypris larvae actively reject flow environments that will be suboptimal for suspension feeding in the early post-settlement phase. Our study suggests that larval choice can be adaptively connected to a specific part of the life cycle, in this case the very sensitive time after metamorphosis."
http://www.esajournals.org/doi/abs/10.1890/0012-9658(2006)87[1960:BLASFE]2.0.CO;2

FLOW-DRIVEN VARIATION IN INTERTIDAL COMMUNITY STRUCTURE IN A MAINE ESTUARY

"....High flows increased the growth of barnacles,...."
http://www.esajournals.org/doi/abs/10.1890/0012-9658(1998)079[1395:FDVIIC]2.0.CO;2

Settlement behavior of Chthamalus anisopoma larvae largely determines the adult distribution

"In this study, I examined a series of alternative hypotheses relating to the factors that could be responsible for limiting the distribution. Post-settlement factors appear to be unimportant because settlement was largely restricted to areas within the adult distribution. Two processes could account for the high correlation between settlement and adult distributions. First, hydrodynamic factors could restrict deposition of larvae to sites that coincidently were in areas in which individuals could survive to maturity. Second, larvae may choose to settle only on sites where they can survive to maturity. Of the two, the later was supported as settlement could be induced on surfaces outside the adult distribution using transplanted adult conspecifics as cues. Thus, competent larvae were present outside the adult distribution of Chthamalus zone but did not settle under normal conditions. Also, there was no evidence that pre-emption of space by other sessile species, by itself, restricted the distribution of Chthamalus. Settlement within the existing adult distribution may be an evolutionary response to increased mortality for individuals settling outside the adult distribution compared to those settling within it."
http://www.springerlink.com/content/h18u4rh81561p020/

Larval habitat selection, not larval supply, determines settlement patterns and adult distribution in two chthamalid barnacles

"Despite recent emphasis on supply and recruitment in controlling adult population structure, the importance of post-recruitment factors in the benthic environment remains. The balance between recruitment and post-recruitment factors has been debated at length in considering whether populations are ‘recruitment limited’ (see Caley et al. 1996; Chesson 1998; for reviews). This concept (sensuDoherty 1981) recognizes two extreme situations where local adult abundance is either determined solely by the input of recruits, or solely by interactions after recruitment. However, it is now generally recognized that neither of these extremes is likely to apply to many populations (Chesson 1998). It is more likely that fluctuating levels of recruitment interact with density-dependent processes to control adult abundance, i.e. both non-equilibrial and equilibrial concepts apply to most populations."
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2656.2005.00985.x/full



There is a very strong research base on this topic.

I would look into algal colonization operating as a precursor to larval settlement.
Any assumptions made over recruitment of the barnacle must be take in as a whole system approach to the fouling community establishment and growth over time.

Note- the very careful establishment of substrata micro texture optimization investigated in the research I quoted above is trumped in a single day by algae colonization.
The turbulence you are imagining must be viewed in light of a boundary layer structure/dynamic which is filled by settlement precursors- the algae, bryozoa, etc etc etc.

Look into 'Fouling Community Succession':

http://scholar.google.com/scholar?hl=en&as_sdt=0,21&q=fouling community succession

From field to forest eh?