A summer of record-breaking temperatures and drought is threatening the ecological balance of rare chalk streams -- rivers formed on chalk beds that are largely unique to England -- and the fish that depend on them.
Wading through a branch of the Itchen near Winchester, Robert Wellard, director of fisheries at the Piscatorial Society and a recreational angler, dipped a thermometer into the clear water, drawing a reading of 17C.
"We should be mor…