Another unwanted pest

[Guest]

This looks to be a nasty little fella and I would hate to think if what he does to smaller things. Also an interesting plea from consider what the talks that have been going on about anti fouling

 

It will likely spread to most areas of marine human activity throughout New Zealand in the near future, so please take care this summer when transporting your boat between different areas and think about what uninvited guests you may be taking along for the ride.

 

''Maintaining a clean and antifouled boat hull is one of the best defences we have against the spread of marine invaders and pests."

 

http://www.stuff.co.nz/environment/6377 ... um=twitter

[Grinna 2]

These guys are a species of Caprellid amphipod. We already have some Caprellids here in NZ that are native (or at least naturalised) and have been here ever since anyone started looking for them, but they're nowhere near the size of Caprella mutica.

 

These beasties are not primary colonisers of underwater surfaces. They hang out in seaweed (which is why they look like that) and feed on other little beasties that swim past or feed on the bryozoans and seaweed ... meaning that you're most unlikely to find them on the hull of a vessel that is kept even remotely clean. Your boat would have to be a bit of a mussel farm to find these guys setting up shop there. A moderate level of maintenance should be enough to keep these little buggers off your crew list.

 

I know that most of you guys keep your underwater surfaces pretty clean, but just remember its kinda important to give the boat's bum a bit of a scrub before you sail from one area to another to try to avoid transporting hitchhikers and spreading things around quicker than they would otherwise spread.

[Guest Crafty 1]

These guys are a species of Caprellid amphipod. We already have some Caprellids here in NZ that are native (or at least naturalised) and have been here ever since anyone started looking for them, but they're nowhere near the size of Caprella mutica.

 

These beasties are not primary colonisers of underwater surfaces. They hang out in seaweed (which is why they look like that) and feed on other little beasties that swim past or feed on the bryozoans and seaweed ... meaning that you're most unlikely to find them on the hull of a vessel that is kept even remotely clean. Your boat would have to be a bit of a mussel farm to find these guys setting up shop there. A moderate level of maintenance should be enough to keep these little buggers off your crew list.

 

I know that most of you guys keep your underwater surfaces pretty clean, but just remember its kinda important to give the boat's bum a bit of a scrub before you sail from one area to another to try to avoid transporting hitchhikers and spreading things around quicker than they would otherwise spread.

 

Jeez grinna you're on fire and i agree with you (2x today ) Most racing guys spread very little between ports (NZ and the world) because we are anal about speed and clean bums. (thats not a drug / gay related comment ).

 

The big culprits are ships (coastal and overseas), plus those cruising guys who don't clean thier boats bums enough.

[Grinna 2]

As a marine biologist with 23 years experience working in and around much of NZ's coastline and a few forays into the south pacific I do have one or two clues about one or two things. Not everything by any means (its a big topic to cover), but I get to know little bits of something about a wide(ish) range of marine biological issues around the joint.

 

I did my Masters on little critters like these.

[wheels 543]

ugly looking critters. Good thing they are just 40mm.

Not as ugly as those white things they dug up from 7000m last week though.

[Grinna 2]

Oh go on Wheels, I'm sure they'd taste OK BBQ'd or sauteed in garlic butter.

[Guest]

ugly looking critters. Good thing they are just 40mm.

Not as ugly as those white things they dug up from 7000m last week though.

 

Yeah, na some off the things scurring around the touchtanks at the american and italian bases down south were a hell of a lot scarier than that

[DrWatson 381]

I'm pretty sure I've seen the smaller species of these on hulls in AKL.

about 5-10mm.

 

wasn't a super clean hull to start with, but was still interesting to note.

 

big on more effective antifoul, I say.

 

and on that matter, how good is teflon in your antifoul, and is it legal for racing?

[wheels 543]

Yep Teflon is legal. It is indeed used among many other slippery things. It doesn't work any better than most. You have to have to have a regularly used Hull and reasonable speed to keep the surface clean. The "glues" that Marine life use to adhear are just amasing eh.

I tried something with my speed log. I had a tube of that orange coloured Silicon gasket maker. I coated the log with it and was careful to ensure the little wheel still went wrong. It stopped working about 6months later and I thought oh well so that doesn't work. Last week I decided to pull it out and inspect it. Now this is 18months after I first coated it. To my surprise, it was totaly clean. Spotless in fact. But what was stopping it were little critters. Two worms that looked like some kind of centerpede had wrapped themselves inside and these little things that were attached at one end and wriggled away at the other had got inside. So the wheel was being stopped from going around. Yet it was clean of all growth. Hmmm.

The best result I have had so far with stopping growth on the Log was the use of Lanocote. A good heavy coat of the stuff lasted 12months and at the end of the 12months, I just gave it a simple clean. No lanocote won't work on everything. It will wash away in any high wash area.

[PaulR 3]

Perhaps the marina piers and fingers need cleaning first as there is generally more marine growth there than on the dirtiest hull, IMHO. Perhaps the marina piers and fingers need cleaning first as there is generally more marine growth there than on the dirtiest hull, IMHO.

[Grinna 2]

Interestingly, I was recently involved in a Biosecurity assessment for an Auckland marina which involved sampling biological communities along the breakwater walls, the timber piles and the marina basin sediments. What surprised me the most was that MAF Biosecurity weren't actually interested in the floating pontoons that make up the marina piers and fingers, they were only interested in the pilings (which were basically bare).

 

This was a bit of a specific investigation in preparation for a specific event, rather than a general "look see" to find out what's growing in the marina generally. The general biosecurity monitoring work is conducted by MAF Biosecurity surveillance teams ... or at least agents working for MAF Biosecurity ... on a regular basis around various harbours and ports. For surveillance investigations I understand they look at pontoons, sediments, walls, piles and all sorts of stuff.

 

I agree that the greatest marine biosecurity threats to NZ would seem to come from commercial shipping as opposed to small craft moving internationally and locally. Having said that, small craft moving around the country can help to spread nasties faster once they get established.

[Guest Crafty 1]

Interestingly, I was recently involved in a Biosecurity assessment for an Auckland marina which involved sampling biological communities along the breakwater walls, the timber piles and the marina basin sediments. What surprised me the most was that MAF Biosecurity weren't actually interested in the floating pontoons that make up the marina piers and fingers, they were only interested in the pilings (which were basically bare).

 

This was a bit of a specific investigation in preparation for a specific event, rather than a general "look see" to find out what's growing in the marina generally. The general biosecurity monitoring work is conducted by MAF Biosecurity surveillance teams ... or at least agents working for MAF Biosecurity ... on a regular basis around various harbours and ports. For surveillance investigations I understand they look at pontoons, sediments, walls, piles and all sorts of stuff.

 

I agree that the greatest marine biosecurity threats to NZ would seem to come from commercial shipping as opposed to small craft moving internationally and locally. Having said that, small craft moving around the country can help to spread nasties faster once they get established.

 

Agree, and yes i wonder how thorough MAF is.

 

Hey grinna, since you know your stuff, can you answer a question for me.

 

Can Didymo survive in salt water or is it a fresh water pest only.

 

The reason i ask is i came up with a hair brained scheme (with some mates and a few beers under the belt) that went like this...

 

1. Starting at the most up stream limit of a river where Didymo is present. Seal of zones (200M lots?) and dose with salt (sodium chloride?) until didymo is dead then work down stream (with a buffer zone between each lot) to the sea.

 

2. instead of salt dosing you could pump a lot / zone free of water and spray the area with something?

 

would that work? or should i stick to my day job?

 

i thought we could get some of the 200,000 umemployed to do this in return fopr the dole..

[Grinna 2]

I'm pretty sure that Didymo is a freshwater species only and as such it would probably not cope with saltwater very well. The problems I see with your cunning plan there Crafty include the length of time you'd need to flood the area of stream with saltwater (like several days to be sure), the issues with sealing off sections of stream, what do you do with the freshwater coming downhill all the time, you're not only going to kill the Didymo but everything else in the stream as well. That sort of stuff.

 

Nice idea, but could be quite difficult to do logistically. I don't think that killing Didymo is the problem, I think the issue is not killing everything else at the same time.

 

I know of a similar approach to a midge problem in a sewage treatment plant effluent holding pond. Basically midges were breeding like wildfire in the holding pond and causing issues so someone had the bright idea of flooding the holding pond with seawater periodically. It worked to a degree in that it limited the number of midges, but backfired in that it created ideal conditions for another type of midge which bred faster and was more of a problem. They ended up using a chemical solution that retards growth in insects but that has implications for crabs and shrimps and other critters when it all gets discharged into seawater.

 

Commercial shipping can't be blamed for the introduction of Didymo into NZ streams so international travelling recreational users (analogous to small craft travelling internationally) can have impacts in terms of biosecurity.

[Guest Crafty 1]

I'm pretty sure that Didymo is a freshwater species only and as such it would probably not cope with saltwater very well. The problems I see with your cunning plan there Crafty include the length of time you'd need to flood the area of stream with saltwater (like several days to be sure), the issues with sealing off sections of stream, what do you do with the freshwater coming downhill all the time, you're not only going to kill the Didymo but everything else in the stream as well. That sort of stuff.

 

Nice idea, but could be quite difficult to do logistically. I don't think that killing Didymo is the problem, I think the issue is not killing everything else at the same time.

 

I know of a similar approach to a midge problem in a sewage treatment plant effluent holding pond. Basically midges were breeding like wildfire in the holding pond and causing issues so someone had the bright idea of flooding the holding pond with seawater periodically. It worked to a degree in that it limited the number of midges, but backfired in that it created ideal conditions for another type of midge which bred faster and was more of a problem. They ended up using a chemical solution that retards growth in insects but that has implications for crabs and shrimps and other critters when it all gets discharged into seawater.

 

Commercial shipping can't be blamed for the introduction of Didymo into NZ streams so international travelling recreational users (analogous to small craft travelling internationally) can have impacts in terms of biosecurity.

 

Thanks for that. i will have to come up with another cunning plan

 

Interesting your comment on Commercial v Recreational. which makes sense if it cannot survive in Salt water. So it Could be the Jet boater type guys? (world champs down south island) etc...

[Grinna 2]

Or simply fishing gear.

[wheels 543]

Yep most of the "Rock Snot", if not all of it, came from fishing gear. Trout fishing to be exact. It got into the small streams and high country lakes that Jetboats haven't a hope of getting into, along with the bigger rivers of course. There is a Algaecide they can use and have used it. Doing much as you have thought Crafty. But they have only treated small streams etc simply because it is too hard to do rivers and lakes. It does not like fast flowing water by the way and we do have a Native NZ species of the growth. Diddymo happens to be a very aggressive version.