Protista:  The  Algae  and  Heterotrophic  Protists

Chapter  15

Ecology  of  Protists

Oldest  eukaryotes~1.8  billion years  old

Most  protists are  aquatic:  either  in  oceans  or  marine  coastlines  or  freshwater  lakes,  ponds  and  streams

Few  live  terrestrially

Contain  >  12  phylaKingdom  Plantae contains  ~11  phyla

Grouping  the  Protists

Kingdom  Protista

plants,  fungi,  or  animals

Paraphyletic

Made  up  of  single  celled,  colonial,  or  multicelledeukaryotes  

Multicellular eukaryotes  are  not  differentiated  into  tissues  though

Ecology  of  the  Protists

Plantae)  but  of  the  aquatic  systemsPlay  similar  ecological  roles  of  plants

Fix  CO2   release  O2Represent  the  base  trophic level

Remember  cyanobacteriaAutotrophic  plankton   phytoplankton

Plankton

This  occurs  when  calcium  carbonate  accumulates  as  scales  covering  phytoplankton

When  they  die  this  calcium  carbonate  sinks  to  the  bottom

Plankton

Haptophytes and  dinoflagellatesproduce  sulfur  compounds

Leads  to  formation  of  clouds  when  excreted  as  sulfur  oxidesReflect  sunlight  global  cooling

Rapid  increases  of  

rain

Plankton

Also  have  extremely  rapid  responses  to  nutrient  input

Often  cause  toxic  blooms,  red  tides  and  hypoxia

Algae  (kelp)

intertropical regions.  Yet  if  in  any  country  a  forest  was  destroyed,  I  do  not  believe  nearly  so  many  species  of  animals  would  perish  as  would  here.    

-­‐Charles  Darwin  in  reference  to  the  kelp  forests  off  Tierra  del  Fuego,  Chile   June  1834

Kelp

Kelp  also  weigh  heavily  upon  ocean  ecology  Whereas  terrestrial  forests  require  +  30  years  to  develop  kelp  forests  can  grow  in  ~  3  yearsTerrestrial  forests  are  strongly  associated  with  3  phyla  (Arthropoda,  Annelida,  and  Chordata)

Kelp  forests  are  associated  with  >  10  phyla!  

Chordata,  Arthropoda,  Annelida,  Echinodermata,  Bryozoa,  Cnidarian,  Mollusca,  Platyhelmenthes,  Brachiopoda,  Porifera +  more  

Kelp

Functions  of  kelp  forests:Provide  a  basal  trophic level

Dampen  wave  action  on  shore

Reduce  light  and  facilitate  low  light  understory  species

Provide  shelter  for  predator  prey  stabilization

Kelp

May  also  fix  nutrients  on  landArid  islands  with  productivity  rely  upon  kelp  detritus

Fixed  C  and  N  from  bird  and  mammal  feces  in  island  systems  is  often  correlated  with  shoreline  to  area  ratio

More  shoreline  =  more  washed  up  kelp  =  more  C  and  N  fixed  through  birds  and  mammals  =  greater  productivity

Kelp

Channel  Islands  California  

Kelp

What  does  the  Japanese  whaling  industry  have  to  do  with  Pacific  kelp  forests?Post  WWII  whaling  targeted  the  great  whaleGreat  whales  represented  a  huge  amount  of  energy  removed  from  the  system  ~  200x  109  caloriesThe  predator  of  the  great  whale,  the  killer  whale,  has  to  use  other  energy  sources  to  fill  energy  demands  

A  single  male  requires  >  240,000  calories  a  day!!!

Kelp

Killer  whales  started  

chainFrom  1990-­‐ 2000  sea  otter  populations  declined  ~  25%  per  year!Even  when  great  whale  populations  are  low,  predation  index  is  still  relatively  low

Kelp

The  energy  calculated  from  estimated  prey  sea  otters  (around  25%  of  the  population)  accounts  for  roughly  more  than  1  killer  whale  pod,  or  around  1/40  of  the  population  demand

Kelp

Kelp?Sea  otters  eat  sea  urchinsSea  urchins  eatupon kelpPredation  of  sea  otters  by  killer  whales  releases  sea  urchins  and  contributes  to  rapid  deterioration  of  kelp  beds

Approx  1/10  the  size  of  12  

Lessons  From  Kelp!

Not  an  isolated  incident!The  same  anthropogenic  mediated  depletion  of  top  down  predation  of  sea  urchins  occurred  in  the  Atlantic

Removal  of  cod,  crabs,  and  lobsters  freed  sea  urchins  from  predation

Top  down  pressure  has  significant  impacts  upon  ecosystems!

Removal  of  wolves  from  Yellowstone  led  to  nearly  0  recruitment  of  aspens  due  to  increased  elk  herbivory

Lessons  From  Kelp!

Biodiversity  is  important!California  kelp  beds  have  suffered  numerous  apex  predator  depletions  and  shifts  and  kelp  deforestation  is  brief  at  max

More  indirect  interactions  buffer  the  whole  trophicsystem  from  cycling  out  of  control  with  the  loss  of  one  species

Diverse  food  webs  allow  for  competitive  interactions  to  buffer  population  explosions

Lessons  From  the  Office?

worst  enemy.  And  the  enemy  of  my  enemy  is  my  friend.  So  Jim,  is  actually  my  friend.  But,  because  he  is  his  own  worst  enemy,  the  enemy  of  my  friend  is  my  enemy  so  actually  Jim  is  my  enemy.  But-­‐-­‐Dwight  Schrute