▁of ▁different ▁regional ▁cro pping ▁systems . ▁ ▁The ▁loss ▁of ▁soil ▁fert ility ▁due ▁to ▁er os ion ▁is ▁further ▁problem atic ▁because ▁the ▁response ▁is ▁often ▁to ▁apply ▁chemical ▁fert il izers , ▁which ▁leads ▁to ▁further ▁water ▁and ▁soil ▁poll ution , ▁rather ▁than ▁to ▁allow ▁the ▁land ▁to ▁reg ener ate . ▁ ▁Sed iment ation ▁of ▁aqu atic ▁e cos ystem s ▁So il ▁er os ion ▁( es pecially ▁from ▁agricult ural ▁activity ) ▁is ▁considered ▁to ▁be ▁the ▁leading ▁global ▁cause ▁of ▁diff use ▁water ▁poll ution , ▁due ▁to ▁the ▁effects ▁of ▁the ▁excess ▁sed iments ▁flow ing ▁into ▁the ▁world ' s ▁water ways . ▁The ▁sed iments ▁themselves ▁act ▁as ▁poll ut ants , ▁as ▁well ▁as ▁being ▁carri ers ▁for ▁other ▁poll ut ants , ▁such ▁as ▁attached ▁p estic ide ▁mole cules ▁or ▁heavy ▁met als . ▁ ▁The ▁effect ▁of ▁increased ▁sed iments ▁loads ▁on ▁aqu atic ▁e cos ystem s ▁can ▁be ▁cat ast roph ic . ▁S ilt ▁can ▁sm other ▁the ▁sp aw ning ▁b eds ▁of ▁fish , ▁by ▁filling ▁in ▁the ▁space ▁between ▁gra vel ▁on ▁the ▁stream ▁bed . ▁It ▁also ▁reduces ▁their ▁food ▁supply , ▁and ▁causes ▁major ▁resp ir atory ▁issues ▁for ▁them ▁as ▁sed iment ▁enters ▁their ▁g ills . ▁The ▁b iod iversity ▁of ▁aqu atic ▁plant ▁and ▁alg al ▁life ▁is ▁reduced , ▁and ▁in verte br ates ▁are ▁also ▁unable ▁to ▁surv ive ▁and ▁reproduce . ▁While ▁the