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6.0. Channel  /  Habitat  /  Biodiversity       AIMS:  Increase  connectivity  with  the  floodplain,  reduce  impoundment  and  barriers  to  fish,    


improve resilience  to  increasing  temperatures,  enhance  habitats  for  wildlife  and  control  invasive   species.  

6.1 What  are  the  problems?   Structure  and  Function   Chalk   streams   have   been   historically   modified   to   suit   a   variety   of   human   purposes   such   as   agriculture,  fisheries,  flood  risk  management  and  the  development  of  watercress  beds  and  mills.  The   various   modifications   have   altered   the   natural   character   of   the   river   and   led   to   systems   being   potentially  over-­‐widened,  over  deepened,  impounded  and  disconnected  with  the  floodplain.   Barriers  to  Fish     In   channel   weirs   and   structures   are   generally   linked   to   negative   impacts   on   the   physical   and   ecological  condition  of  the  river.  In  addition  to  altering  the  depth  and  velocity  of  flow,  structures  can   also  impact  on  the  biological  connectivity  of  the  river  by  limiting  fish  and  invertebrate  passage.   Riparian  Management     The  Test  and  Itchen  supports  a  thriving  fisheries  industry  and  the  majority  of  the  river  is  intensively   managed   to   accommodate   sport   fisheries.   Inappropriate   vegetation   management   practices   can   impact   on   the   diversity   of   riparian   habitats,   over   widening   of   section   and   the   rivers   ability   to   restore   it’s  natural  features.   Water  Temperature   Climate  change  models  forecast  that  average  summer  air  temperature  will  rise  by  between  2  and  4   degrees   celsius.   Rivers   and   the   freshwater   ecosystems   they   support   are   particularly   sensitive   to   changes   in   climate   and   water   temperature.   For   example   a   rise   in   water   temperature   above   22   degrees  celsius  for  more  than  seven  consecutive  days  can  be  lethal  for  brown  trout.     Non-­‐native  Invasive  Species     Traditional   chalk   stream   flora   and   fauna   faces   increasing   pressure   from   a   range   of   non-­‐native   invasive   species   that   have   taken   hold   within   the   catchment.   These   include   Himalayan   Balsam,   American  mink  and  most  recently  the  American  signal  crayfish.   6.2  Where  are  the  pressures?   There   are   numerous   sources   of   data   and   evidence   available   to   show   the   assessment   of   ecological   health  and  biological  richness  across  the  catchment.  Designated  sites  are  classified  according  to  their   condition   and   rivers   and   other   aquatic   ecosystems   are   assessed   via   a   number   of   metrics,   included   in   the  WFD  ecological  assessments,  some  of  which  have  been  be  mapped  in  Figures  28-­‐33  to  highlight   where  certain  pressures  are  most  significant.  


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TICP Catchment Action Plan (low res)  

TICP Catchment Action Plan (low res)  

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