Sample Response: The population of unionid mussels in the Hudson River decreased after zebra mussels were introduced. Zebra mussels, a nonnative species, competed with the unionid mussels for food. The zebra mussels were able to outcompete the unionid mussels, allowing the zebra mussel population to increase dramatically over six years. The unionid mussel population decreased due to a lack of food.

What did you include in your response? Check all that apply.

The population of unionid mussels in the Hudson River decreased after zebra mussels were introduced.
Zebra mussels competed with unionid mussels for food.
The zebra mussels were able to outcompete the unionid mussels.
The unionid mussel population decreased due to a lack of food.

1.The  Zebra  Mussel  (Dreissena  Polymorpha)  are  small  organisms

that  are  native  to  the  Black,  Caspian,  and  Azov  Seas.  They  are  found  non-natively  throughout  Europe  and  America.  2.It  is  believed  that  they  were  unintentionally  introduced  into  North  America  by  the  emptying  of  ballast  tank  water  from commercial  transatlantic  ships  into  the  Great  Lakes.  “When  ballast  tanks  are  filled,  many  forms  of  aquatic  life  in  the source  water  are  drawn  into  the  tanks.  Once  in  ballast tanks,  organisms can  be  transported  to  other  areas  and  subsequently  discharged  into waters  at  foreign  ports,”  the  Lake  George  Association  explained.

3.The  Zebra  Mussel  is  able  to  spread  so  quickly  throughout  its

environment  by  the  large  numbers  of  the  offspring.  Each  female  Zebra  Mussel  can  produce  up  to  a  million  offspring  called  veligers,  that  sur-

vive  by  attaching  themselves  onto  any  hard  surface,  which  may  be transported  to  other  water  sources,  spreading  the  Zebra  Mussels  to  new  water  sources.  4.Zebra  Mussels  eat  large  quantities  of  microscopic plants  and  animals  that  are  at  the  base  of  the  food  web.  They  also carry  inside  them  toxic  materials  that  harm  anything  that  consumes  them,  like  fish.  As  well  as  this,  they  attach  themselves  to  native  muss-

els,  making  it  harder  for  the  mussels  to  eat,  or  do  anything  at  all.

5.Zebra  Mussels  cause  problems  for  humans,  not  only  other  sea

life.  They  clog  up  water  pipes,  used  for  municipal  drinking  water,  and clog  the  water  intake  pipes  of  small  private  residents,  often  corroding  iron pipes,  and  can  as  well  clog  fire  hydrants,  creating  problems  for  firefighters.  Zebra  Mussels  often  make  colonies  on  docks,  boat  bottoms  and engines,  and  buoys,  which  corrode  them,  often  destroying  them. They  will  cause  swimming  areas  to  be  deserted  because  of  them  washing  up on  shores,  and  colonizing  on  rocks,  making  people  avoid  the  sharp  edges.  Zebra  Mussels  also  create  drag  in  boats,  because  of  them  colonizing  on  them,  which  increases  fuel  consumption,  polluting  waters.  

6.Zebra  Mussels  are  being  removed  from  areas  they  are  not  

native  to,  because  of  the  problems  they  create  in  those  areas  for wild-

life,  and  for  humans.  It  is  encouraged  for  people  to  check  on  boats, docks,  and  buoys  for  Zebra  Mussels  when  they  are  at  lakes,  contact professionals  immediately  that  will  see  to  the  removal  of  them,  and  to store  the  Zebra  Mussel/s  in  rubbing  alcohol  until  professionals  arrive  and  take  care  of  the  situation.

because photosynthesis could not occur (apex)