net was pulled by hand. One dredge haul, or a 

 nearly equivalent volume of sediment collected by 

 shovel, and one 2-minute net haul were taken at 

 each station. "We collected water samples at each 

 station with a Van Dom bottle for determination 

 of temjjerature, salinity, and pH. Water depth was 

 measured by handline. 



"We removed the mollusks from bottom samples 

 by sieving sediment and bottom debris on a screen 

 of 0.701-mm. mesh (Tyler #24 screen*). Before 

 sieving, we removed a subsample of sediment 

 (about 300 cc.) fi'om each bottom sample for anal- 

 ysis at the Sedimentological Laboratory, Florida 

 State "University. Their analyses included meas- 

 urements of grain size, calcium carbonate, organic 

 nitrogen, and organic carbon as well as statistical 

 characteristics of mean grain size, sorting (as 

 standard deviation), skewness, and kurtosis (Tay- 

 lor and Saloman, 1969). 



* References to trade names In this publication do not Imply 

 endorsement of commercial products. 



DIVERSITY AND ABUNDANCE 

 OF MOLLUSKS 



"We collected and identified 64 species of mol- 

 lusks from bottom samples taken in Hillsborough 

 Bay (Appendix). Of these species only 36 were 

 represented by living individuals; furthermore, 

 live mollusks were collected at only 26 of the 45 

 stations sampled. Samples at all stations where 

 live mollusks were collected always included one 

 or more of four species, i.e.: dwarf surf clam 

 {MuJinia lateralis), paper mussel (Amygdahim 

 papyria), common eastern nassa {Nassarhis 

 vibese), and stout tagelus {Tagelus phbems). On 

 an indi^'idual basis, M. lafernlis was present in 65 

 percent of the station samples that contained live 

 mollusks; the incidences of A. papyria, N. vibex., 

 and T. pleheius were 58, 54, and 35 percent, respec- 

 tively (table 1) . The next most numerous mollusks 

 were the crown conch {Melongena corona) and the 

 lunar dove-shell {Mitrella lunata) which occurred 

 at 6 of the 26 stations where live mollusks were 

 found. 



Table 1. — Numbers of living mollusks by species and station collected from Hillsborough Bay, Fla., August and September 1963 



(Number of times a station sampled in parentheses] 



Station numbers 



7-1 7-2 

 (2) (2) 



7-3 

 (2) 



8-1 

 (2) 



(2) 



8-3 8-4 



(2) (2) 



8-5 

 (2) 



8-« 8-7 

 (1) (2) 



(2) (2) 



8-10 9-1 9-2 9-3 9-4 9-5 

 (2) (1) (2) (2) (2) (2) 



Mulinia lateralis 



AmvQdalum papyria 



Nassarius vtber 



Taodus plebefus 



Melongena corona 



Mitrella lunata 



Tellina versicolor 



•Ensis minor 



Mercenaria campeckiensis, 



Macoma tenia 



Crepidida plana 



Bittium rarium 



Thracia sp 



Modiolus americanus 



Anadara transversa 



Crassostrea lirginica 



Retusa canaliculata 



Polinices duplicatus 



Odostomia acutidens 



Mystella planulata 



Epitonium humphreysi 



Corbula caribaea 



Anachis obesa 



Tagelus divisus 



Urosalpinz tampaensis. . . 



Nucula prozima 



Natica pusilla 



Laevicarium mortoni 



Haminoea succinea 



Epitonium angulatum 



Crepidula fornicata 



Corbula barralliana_ 



Brachidontes exustus 



Polymesoda caroliniana^,. 



Acteon punctostriatus 



Ischnocliiton papillosus 



2 . 

 40 



Total number species 



Total number individuals.. 



800 1 

 1 



122 4 



5 

 69 



5 

 925 



194 



U.S. FISH AND WILDLIFE SERVICE 



