dubois@uwmacc.UUCP (Paul DuBois) (07/30/85)
J Chervinski, "Salinity tolerance of the guppy, _Poecilia reticulata_
Peters", J Fish Biology, 24(4), April 1984, 449-452.
Abstract:
Experiments were conducted to determine the adaptability of the guppy
to various salt concentrations. The guppy, _Poecilia reticulata_,
(total length 11-40 mm) were subjected to abrupt and gradual changes
from fresh water (salinity=0.1%) to various salinities (%). No
mortality occurred when the fish were transferred from fresh water to
50% sea water (19.5%). Through gradual adaptation from 50% sea water
to [sic - remove word?] 80% of the fish were able to tolerate 100%
(39%) sea water for 7 days. After a 7 day stay in sea water, fish were
readapted to fresh water during a 3 h period. Through gradual
adaptation fish were also able to tolerate salinities ranging from
39.0% (100% sea water) to 58.5%. After a 30 day stay in 150% sea water
(58.5%), fish were readapted to fresh water over a 5 h period. The
results indicate that they were well able to tolerate the abrupt change
from 100 or 150% sea water to fresh water. Females that stayed in 150%
sea water (58.5%) for 30 days had embryos in the gonads.
Table 1. Mortality of _Poecilia reticulata_ (%) after direct
transfer from fresh water to various saline concentrations
Mortality at various
concentrations of sea water
Time from start of
experiment (h) 0% 50% 60% 70% 90%
-----------------------------------------------------
8 0 0 0 20 100
24 0 0 10 100
48 0 0 20
72 0 0 20
96 0 0 20
120 0 0 20
144 0 0 20
168 0 0 20
The practical significance of this work is that brackish water and salt
marshes are favorable mosquito breeding habitats. Stocking of guppies,
which feed on the mosquito larvae, is thus a pest control measure.
The significance may also extend to some of the discussion in this
newsgroup...I thought that perhaps some of the readers might be
interested.
--
|
Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+--
|
"Why are you standing on one leg?" |
"I'm trying to see if I'm a stork."lonetto@phri.UUCP (Michael Lonetto) (08/07/85)
> > J Chervinski, "Salinity tolerance of the guppy, _Poecilia reticulata_ > Peters", J Fish Biology, 24(4), April 1984, 449-452. > > Table 1. Mortality of _Poecilia reticulata_ (%) after direct > transfer from fresh water to various saline concentrations > > Mortality at various > concentrations of sea water > Time from start of > experiment (h) 0% 50% 60% 70% 90% > ----------------------------------------------------- > 8 0 0 0 20 100 > 24 0 0 10 100 > 48 0 0 20 > 72 0 0 20 > 96 0 0 20 > 120 0 0 20 > 144 0 0 20 > 168 0 0 20 > > The practical significance of this work is that brackish water and salt > marshes are favorable mosquito breeding habitats. Stocking of guppies, > which feed on the mosquito larvae, is thus a pest control measure. > > The significance may also extend to some of the discussion in this > newsgroup...I thought that perhaps some of the readers might be > interested. Very interesting. What does it have to do with evolution? The guppies don't "evolve" in 168 hours. They already have the ability to live in salt water. Swamp fish tend to be very adaptable with regard to water quality. Is that the evolution you refer to? Please be more specific. -- ____________________ Michael Lonetto Public Health Research Institute, 455 1st Ave, NY, NY 10016 (allegra!phri!lonetto) "BUY ART, NOT COCAINE"
dubois@uwmacc.UUCP (Risky Rat) (08/09/85)
>> [Paul DuBois] >> J Chervinski, "Salinity tolerance of the guppy, _Poecilia reticulata_ >> Peters", J Fish Biology, 24(4), April 1984, 449-452. >> ... table and abstract deleted... >> The practical significance of this work is that brackish water and salt >> marshes are favorable mosquito breeding habitats. Stocking of guppies, >> which feed on the mosquito larvae, is thus a pest control measure. >> The significance may also extend to some of the discussion in this >> newsgroup...I thought that perhaps some of the readers might be >> interested. > [Michael Lonetto] > Very interesting. What does it have to do with evolution? The guppies > don't "evolve" in 168 hours. They already have the ability to live in > salt water. Swamp fish tend to be very adaptable with regard to water > quality. Is that the evolution you refer to? Please be more specific. It doesn't have anything to do with evolution. I wasn't referring to anything about evolution. (pre-reply comment: Golly! Often we see the statement that "all 'pro-creation' writings of creationists are simply anti-evolution statements." I guess one unfortunate manifestation of this expectation is that when something not anti-evolution appears, it becomes incomprehensible?) Andrew Koenig asked, long ago, about the consequences, with regard to fish mortality, of a flood. The question was motivated, I believe, by the expectation that the difference in habitat of fresh- and salt-water fish would would cause the death of all the members of one or both groups. I mentioned, in response to the original question, the existence of salmon, and also a quotation from _The Origin_: "[S]alt-water fish can with care be slowly accustomed to live in fresh water; and, according to Valenciennes, there is hardly a single group of fishes confined exclusively to fresh water, so that we may imagine that a marine member of a fresh-water group might travel far along the shores of the sea, and subsequently become modified and adapted to the fresh waters of a distant land." The article by Chervinski also has a bearing on this issue, and when I ran across it recently, I thought that it might be worthwhile posting. It doesn't *prove* a flood of course, nor was that my intent. It shows that in such an eventuality, not all fresh-water fish would die. (It does not show that all fresh-water fish would live.) -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | Ritual and Ceremony: Life Itself. |
stro@ur-univax.UUCP (08/09/85)
well now, if you believe in the flood as described in the Bible, then Noah
took two of every animal that exists on the Earth and brought them on the Ark.
Well, since the Earth's water is more than 70% salt water the flood water
would be salty, so Noah just could have made a giant aquarium ( out of
wood of course ) and put the couple thousand species of freshwater fish
in there and then dumped them in the nearest lake after the flood. Right?
no problem. Well, except that there would not be anymore freshwater anywhere
on Earth - oh well.
- Steve Robiner
University of Rochester
{allegra|seismo|decvax}!rochester!ur-univax!strodubois@uwmacc.UUCP (Risky Rat) (08/14/85)
> [Steve Robiner] > well now, if you believe in the flood as described in the Bible, then Noah > took two of every animal that exists on the Earth and brought them on the Ark. > Well, since the Earth's water is more than 70% salt water the flood water > would be salty, so Noah just could have made a giant aquarium ( out of > wood of course ) and put the couple thousand species of freshwater fish > in there and then dumped them in the nearest lake after the flood. Right? > no problem. Well, except that there would not be anymore freshwater anywhere > on Earth - oh well. It seems to me that if one believes in the flood "as described in the Bible", then one will be unlikely to believe that Noah took fish on the Ark. It also seems to me that, as is often true, the above is characterized by ignorance of the idea being attacked. Whether the account of the flood in the Bible is true or not, the above objection does not really address that account. It only seems to. Another point is that if one wishes to construct a hypothesis (such as that above) one ought also seek to disprove it and/or construct alternatives. In this case, there is little difficulty. Suppose that Noah did as supposed here. What would he do with the freshwater fish, in view of the lack of freshwater? I think that we can all agree that rain exists today, and perhaps we can agree that it would be reasonable to extrapolate its occurrence backwards in time several millenia. We may suppose then, that there would be at least a few freshwater resevoirs being formed, into which the fish could be released. This also has its difficulties (e.g., how to account for global distribution of freshwater fish), and I'm sure some are thinking that I'm off on one of my pedantic over-literal binges, but I do so here to illustrate a point: Not all crap arguments in this newsgroup come from the creationist side. If Mr Robiner wishes to make a statement about with flood, he should (i) first find out what it is supposed to entail, and object that *that*, as opposed to objecting to his own private (i.e., straw) version of it, and (ii) try to think of plausible replies to his objections. The latter is usually a worthwhile exercise. It is virtually never a waste of time to consider how an argument might be received by someone not holding to the same point of view. -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | Ritual and Ceremony: Life Itself. |