. Bulletins of American paleontology. d the 30 ppm contour Bay waters were notmuch different from the normal Bay salinity near34 ppm. Text-figure 33 is the contrasting map showing thelimits at which we found waters concentrated by evap-oration to salinities of 45 and 55 ppm. We found wa-ters up to 60 ppm north of the line marked 55. Salinity and Depth of WaterIt should come as no surprise that changes in salin-ity occur in concert with water depth. At all locationswhere we found the difference between the freshestand most saline water to equal or exceed 30 ppm. thewater was six feet ( m) or
. Bulletins of American paleontology. d the 30 ppm contour Bay waters were notmuch different from the normal Bay salinity near34 ppm. Text-figure 33 is the contrasting map showing thelimits at which we found waters concentrated by evap-oration to salinities of 45 and 55 ppm. We found wa-ters up to 60 ppm north of the line marked 55. Salinity and Depth of WaterIt should come as no surprise that changes in salin-ity occur in concert with water depth. At all locationswhere we found the difference between the freshestand most saline water to equal or exceed 30 ppm. thewater was six feet ( m) or less in depth. Salinity and Mud Content Inasmuch as ranges of salinity are greatest in lessthan six feet ( m) of water and mud content alsoincreases in shallow water, it follows that salinity andmud content are highly correlated. This does not provea causal relation between the two. Ranges of Salinity and Taxon AbundanceWe made comparisons of the abundance of everytaxon common enough to have statistically adequate 34 Bulletin 370. Tcxt-tifiure 3?.—Select mile = kil sampling against its associated range of salinity. Threemajor groups of taxa emerged, characterized by salin-ity ranges of 0-10 ppm, 16-30 ppm and over 30 ppm. In the end, it became apparent that we had dem-onstrated the obvious. In the north, where salinitiesvary widely, there are fewer but larger numbersof individuals. In the central Bay, where swings insalinity are less, there are more taxa but fewer indi-viduals of each taxon. And in the areas of open waterwhere there is minimal salinity variation, there is amaximum number of taxa, many of which are rare. Allof this is obvious from the sample counts alone, andit is general biologic knowledge that fewer animalswill live where the environment is ditficiilt than whereit is equable. Durbin Tabb, who studied the living moUusks of theBay, told me more than 30 years ago that TransenneUcidoes not tolerate salinity swings even though it reachesits maximu
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