And we think the answer has to do with salinity.If you measure salinities of the northern gulf waters now, the northern gulf is what we would refer to as being hyper-saline. Salinities range from about 37 parts per thousand--a measure of saline content of the water--to about 60 parts per thousand, and there are areas of the northern gulf that I've measured with salinity of about 80 parts per thousand. Some of you probably know that average marine salinity is about 35 parts per thousand. So the gulf is very hyper-saline. It seems that Millennia preferred the slightly lower salinities in the high twenties to low thirties that were present when the river was flowing and you had this fresh water input.

Now, we're attempting a very interesting calculation with Mulinia. We're beginning to look at the isotopic composition of the Mulinia shells. If you recall earlier, I told you that if we take the sample of water that's a result of mixing of gulf water and mixing of river water, we can tell you how much of each is in there and where we they came from. We can do the same thing with the shells ofMulinia. By looking at the isotopic profile of these Mulinia shells, we can calculate what the salinity of the water was when these Mulinia shells were alive. So what we're doing is reconstruction of what salinity patterns must have looked like in the northern gulf before we turned off the river. And we're taking this one step further. We're calculating how much water will have to be released annually to restore Mulinia to its former status as the most abundant species in the northern gulf. That's one that's proving to be very interesting.

There are a few other bits of information that we need. There's a time of reproduction of Mulinia, does it require lower salinity year round or just during that period of time. Most of the water from the river would arise in the gulf between the months of May and July, that's when you get the big spring snowmelt. So, does it need lower salinity throughout the year or does it require just a period once per years. And also, is reproductive success dependent on this lower salinity and what type of salinity pattern does it need.

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