y  =  -­‐0.0178x  +  0.8302  R²  =  0.06715  

0  0.2  0.4  0.6  0.8  1  

Large  Oyster  1  

Large  Oyster  2  

Small  Oyster  1  

Small  Oyster  2  

Filtra@

on  ra

te  (m

l  min

-­‐1)  

0  

5,000  

10,000  

15,000  

20,000  

25,000  

30,000  

35,000  

40,000  

45,000  

0   15   30   45  

Concen

tra@

on  (C

ells/ml)  

Time  (min)  

Large  Oyster  1  Large  Oyster  2  Small  Oyster  1  Small  Oyster  2  Large  Oyster  average  Small  Oyster  Average  

The  effect  of  body  size  on  filtration  in  Crassostrea  virginica                                                      

Benjamin  Gibson  &  Andrew  Ellis  

Roger  Williams  University  

Introduction:  

  The   amount   of   oysters   have   an   effect  on   the   amount   of   have   been   known   to   filter  entire   bodies   of   water   in   a   relatively   short  amount  of  time,  however  the  effect  of  body  size  on  individual  filtration  rates  for  C.  virginica  is  an  interesting  concept.  The  null  hypothesis  for  this  experiment  is  that  there  would  be  no  difference  in   filtration   rate   between   large   and   small  oysters.   The   alternative   hypothesis   is   that   the  large  oysters  would  have  an  increased  filtration  rate  relative  to  the  small  oysters.    

Materials  and  methods:  

  Four   oysters,   two   large   and   two   small,  were   obtained   and   each   placed   in   their   own  1000  ml  beaker.  The  concentration  of  Isochrysis  in   each   beaker   was   attempted   to   be   similar  however  there  was  a  difference  of  about  8,000  cells/ml  between  large  oyster  one  and  two  and  a   difference   of   about   4,000   cells/ml   between  small  oyster  one  and   two.   In  order   to  properly  calculate   body   size,   the   body   volume   was  determined   by   placing   each   oyster   in  approximately   450ml   of   water   to  measure   the  displacement.   In   order   to   standardize   the   data  the   filtration   rate   was   divided   by   the   body  volume.    

Results:  

Table  1.  Body  volumes  of  each  oyster  measured  by  the  displacement  in  450ml  of  water.    

Large  oysters   Small  oysters  1  90  

2  72  

1  37  

2  41  

 

 

Figure  1.  Filtration  rates   (ml/min)  as  a   function  of  oyster  size  (large  and  small).    

 

Figure   2.   The   concentration   (cells/ml)   of  isochrysis   in  each  oyster’s  beaker  as  a   function  of  time  (15  minute  intervals).    

Discussion:  

  There   was   little   correlation   between  body   volume   and   filtration   rate.   The   body  volumes   were   Small   oysters   filtered   at   about  the   same   rate,   whereas   the   large   oysters  filtered  at  slightly  different   rates   (fig.  1).  The  r2  value   was   about   0.07   which   is   too   low   to  explain   any   kind   of   correlation   between   body  volume  and  filtration  rate  of  oysters  (fig.  1).  The  oysters   started   at   different   concentrations   of  Isochrysis,   which   could   have   played   an  important   role   in   the   filtration   rates.   Large  oyster  1  had  the  highest  starting  concentration  and   between   0   and   15   minutes   it   filtered   the  

most   which   indicates   that   the   starting  concentration   has   an   effect   on   the   filtration  rate  (fig.  2).    

Conclusion:  

The   results   could   have   been  compromised   due   to   the   amount   of   samples,  having   two   samples   per   variable   would   not  produce   enough   data   to   provide   accurate  results.   The   other   issues   that   could   provide   an  explanation   of   the   lack   of   significant   data  includes  the  difference  in  body  volume  between  “large”  and  “small”  oysters  which  could  lead  to  a  less  noticeable  difference.