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Let's see, split fins was last week and then we had people using carabineers for diving then it was the space boots and now zebra mussels. Yes, I think this must be some sort of stupid sh*t invasion.:-) -----Original Message----- From: "Chris Elmore"<elmorec@at*.ne*> To: techdiver@aquanaut.com Date: Mon Aug 27 03:59:22 PDT 2001 Subject: Re: Zebra Mussel Temp is a factor! >I know things have been slow lately and I want to commend MJB for two >*consecutive* posts that contained no personal attacks or stupidity. I would >like to know, however, what the life cycle of a zebra mussel has to do with >tech diving? Is this more of the rec.scuba invasion we've been seeing >lately? >C. > >----- Original Message ----- >From: "Michael J. Black" <mjblackmd@ya*.co*> >To: <techdiver@aquanaut.com> >Sent: Sunday, August 26, 2001 7:17 PM >Subject: Re: Zebra Mussel Temp is a factor! > > >> Thanks for the scientific insight Richard. I haven't dived Whitefish >> Point for a couple of years, but was impressed with the lack of zebra >> mussels there in 1999. Given that upbound and downbound freighter >> traffic is heavily concentrated there (hence the many wrecks) I was >> pleased to see not a single living zeeb. A park ranger at Isle Royale >> told me a couple weeks ago that there were a few zeebs spotted at Windigo >> (west end of island) but nothing too worrisome. Lake Superior holds the >> secret to knock off these pests, and hopefully guys like you will figure >> that out. >> >> MJB >> >> --- Richard Hayward <hddiver@sy*.ca*> wrote: >> > >> > Hi my name is Richard Hayward, I have been on the list for about 6 years >> > have posted a few times, I am originally from Sault Ste. Marie but now >live >> > in St. Louis (The techdiving scene is non existent in the midwest. Bonne >> > Terre mines could have potential but they only give guided tours there >at a >> > cost of 130$ for two air or nitrox dives yikes! everything else is >quarries >> > unless someone can guide me to something better please!), and have dove >> > Whitefish point and the Straights of Mackinaw tons and also am a well >> > traveled commercial diver. >> > >> > Presently I work with an ecological firm called Ecological Specialists >Inc. >> > as the scientific diving co-ordinator. I am not a malacologist >(specializing >> > in mussels) but work directly with two very well respected malacologists >> > Heidi Dunn and Charles Howard. Ecological Specialist Inc. is located in >the >> > midwest specializing primarily in freshwater mussels among other things. >My >> > job is the identification of North American freshwater mussels for the >> > purpose of estimating population densities, identifying endangered >species, >> > relocation, also for conducting dives per OSHA and USACE regulations >plus >> > many other objectives depending upon the client. It is not scuba, all >> > surface supplied to answer the curious. >> > >> > The ability for a zebra mussel to survive depends on several factors >> > including: >> > >> > 1) Temperature >> > 2) Dissolved Oxygen >> > 3) PH level >> > 4) Calcium levels >> > 5) Salinity levels >> > 6) Water Velocity >> > 7) Turbidity >> > 8) Substrate condition >> > >> > The most important of these factors is temperature, calcium levels and >PH. >> > >> > Temperature - >> > >> > "Temperature plays an important role in the seasonal life cycle and >> > physiology of the zebra mussel. Particular temperature regimes cue major >> > life cycle events such as reproduction and larval development. Zebra >mussel >> > spawning (release of gametes into the water column) will not occur at >> > temperatures below 10 - 16 degrees C for either North American (Herber >et >> > al. 1989, Griffiths et al. 1991, Claudi and Mackie 1994) or European >> > (Kornobis 1977, Stanczykowska 1977, Walz 1978, Borcherding 1991, Sprung >> > 1991) populations. Garton and Hagg (1993) report a threshold of 18 >degrees C >> > for spawning in southwester Lake Erie. Thew water temperature ranges >> > coincide with June - September in most of the the North American >temperate >> > freshwater systems. As temperatures decline in the fall, zebra mussels >begin >> > gamtonesis while good supplies are still adequate... >> > >> > Temperature also has a significant effect on zebra mussel growth. The >term >> > growth is used to describe the accumalation of somatic body tissue. >Shell >> > growth will not occur at temperatures below 3 degrees C (Smit et al. >1992). >> > Temperatures as low as 6 degrees C (Bij da Vaate 1991)... Claudi and >Mackie >> > (1994) report a growth range of 8 - 10 degrees C for Lake St. Clair >mussel >> > populations. >> > >> > Temperature plays a significant role in the survival success of zebra >> > mussels. It is on of the factors that may play a role in limiting the >> > distribution of the animal. However it is important to realize that once >the >> > animals become acclimatized to warmer habitats, the upper thermal >tolerances >> > could shift over several years. Although they can survive temperatures >> > slightly in excess of 30 degrees C for short periods, optimum >temperatures >> > are 0 - 25 degrees C. >> > >> > Values used for determining risk for temperature by the risk assessment >> > calculator are as follows; >> > If the number of months above 12 degrees C is >> > less than 1 - slim to none >> > 1 to 3.999999 - moderate >> > 4 or greater - high " Zebra Mussel information System version 3.0 >> > >> > Here is a link to current lake superior temperature as of today August >25 >> > 2001 it appears to be on average about 12 degrees C >> > http://www.coastwatch.msu.edu/superior/s32.html or >> > http://coastwatch.glerl.noaa.gov/cwdata/lct/glsea.gif which is close to >the >> > right temperature for reproduction but is only that warm for very short >> > periods of the year and it does not appear that it is in the ideal >> > temperature range long enough to support reproduction. The hot spots MJB >> > talks about in Lake Superior also get the warmest during the summer if >you >> > look at temperature histories at these links. >> > >> > >> > Calcium Levels - >> > "Calcium (Ca) is a necessary element in the composition of the bivalve >> > shell. Sprung (1987) reported that 40 - 55 mg of Ca per liter was >sufficient >> > for larval development and that a minimum of 24 mg Ca per liter was >> > necessary for 10% larval survival. Stanczykowska (1977) found calcium >from >> > 28 - 109 mg Ca per liter in lakes with successful zebra mussel >populations. >> > >> > Zebra mussels do not survive to any great extent when there is >insufficient >> > calcium levels. Calcium is a necessary component for shell secretion and >> > formation. >> > >> > The following table (taken from Claudi and Mackie (1994)) illustrate the >> > growth and survival of zebra mussel from waters with varying calcium >levles. >> > >> > Growth and survival Calcium range mg/l >> > no survival 5 to 6 >> > poor growth 10 to 11 >> > Moderate growth 25 to 26 >> > Good growth 35 to >35 >> > >> > Values used for determining risk for calcium values by risk assessment >> > calculator are as follows >> > less than 20.999999 - slim to none >> > 21 - 54.999999 - moderate >> > greater than 55 - high " Zebra Mussel information System version 3.0 >> > >> > PH - >> > "The pH of a body of water will play a role in determining zebra mussel >> > success. pH lower than 7.4 will inhibit zebra mussel larval development >> > (sprung 1987). Kornobis (1977) reports pH from 7.2-8.7 as having little >> > effect on veliger densities in the phytoplankton. Other authors (Dries >and >> > Theede 1974 as referenced by Sprung 1992) reported that survival of >bivalves >> > was higher at pH values between 7.0 and 7.5 Stanczykowska (1977) >reported >> > zebra mussels in lakes with hypoimnetic pH values from 6.6 - 8.0 and >> > epilimnetic values from 8.5 - 7.7. >> > >> > The amount of hydrogen ions in the water or the pH can significantly >impact >> > aquatic life. Bivalve molluscs, such as zebra mussels, are at risk at >either >> > extreme of the pH scale (i.e., below 6 and above 9). >> > >> > The following table (taken from Claudi and Mackie (1994)) illustrates >the >> > survival and growth potential of zebra mussels from waters with >different pH >> > values. >> > >> > Growth and survival pH range >> > no survival 0 - 6.8 >> > poor growth 6.9 to 7.4 >> > moderate growth 7.5 to 7.8 >> > good growth 7.9 to 8.0 >> > best growth >8.0 >> > >> > Note how there is no upper survival limit for the best growth which is >> > contrary to other published information where the incipient lethal >larval >> > level is around 7.4. Apparently, there are different thresholds for both >> > immatures and adult growth. >> > >> > Values used for determining risk for pH values by the risk assessment >> > calculator are as follows >> > 0 to 6.7999999 - slim to none >> > 6.8 to 7.39999999 - moderate >> > 7.4 to 8.999999 - high >> > 9 to 10 - slim to none" Zebra Mussel information System version 3.0 >> > >> > >> > >> > Water quality also suggests a very low calcium level of 5.9 mg/l >reported at >> > one station which is directly related to shell production other stations >> > also reported some low calcium levels. Data available at this link >> > http://oaspub.epa.gov/storpubl/legacy/proc_generate_next and that pH is >also >> > marginally condusive as well relating to poor growth. >> > >> > If you were to put all of these factors together, not just one on its >own, >> > they are probably what is keeping zebras from invading Lake Superior. >> > >> > The international joint commission also has lots of resources available >at >> > this link http://www.ijc.org/ijcweb-e.html >> > >> > I can do much more research to this fact as I have a lot of professional >> > resources at my fingertips. >> > >> > Keep diving everyone, because now that I am in the midwest I miss the >good >> > times. >> > >> > Also the wreck diving in the great lakes is amazing especially whitefish >and >> > the straights of mackinaw, to say they are the best in the world though >is a >> > bold statement. I would definately say that they are one of the best >spots >> > in the world, for number and quality of wrecks, whitefish is deep but >> > amazing, the straights however offer very nice wrecks and most of them >under >> > 100 feet means you can take you whole family there which is nice. The >thing >> > to remember when diving in the Great Lakes is the distance to a half >decent >> > chamber and someone competent in hyperbaric medicine. Just make sure you >> > have your DAN insurance. >> > >> > >> > Dive safe configure right. >> > Richard Hayward >> > >> > >> > -----Original Message----- >> > From: Michael J. Black [mailto:mjblackmd@ya*.co*] >> > Sent: Saturday, August 25, 2001 9:01 PM >> > To: Aquanaut Mail >> > Subject: Zebra Mussels >> > >> > >> > Lake Superior not only has some of the best wreck diving in the world, >> > it has very few zebra mussels compared to the other Great Lakes. Anyone >> > wanna give a good explanation as to why this is? And before you say >that >> > the water is "too clean" or "too cold," consider that even the >scientists >> > don't know, but the low Calcium levels in the water may be part of the >> > reason for the inability of zeebs to thrive in Superior. I have seen >> > shallow wrecks (less than 60 ffw) in Lake Michigan become smothered with >> > zeebs, beginning around 1995, obscurring engine details to the point of >> > making the wrecks undesirable to dive. Deeper wrecks are relatively >spared, >> > but even depth doesn't stop zeebs or their relatives (Quagga mussels) >from >> > latching on. Improved visibility from these filter feeders is often >> > exaggerated by divers, but there is no question that water clarity has >> > improved wherever zeebs have taken hold, some consolation. >> > >> === message truncated === >> >> >> >> __________________________________________________ >> Do You Yahoo!? >> Make international calls for as low as $.04/minute with Yahoo! 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