pyke like the temperature and the oxygen and nutrients levels in the water not too much and not too little. here some male piker chasing after a female after a bit of a song and dance one couple make. these pristine ponds are under threat. intensive farming means insecticides pesticides chemical fertilizers and slurry can all pollute groundwater. and thus the springs that feed the ponds. nitrate from nitrogen fertilizer causes al jewel blooms which use up all the oxygen in bodies of water. various chemicals are bad for aquatic animals and plants. they also threaten the supply of water we humans drink. the level of nitrate in groundwater exceeds the permissible level in more than a quarter of germany. groundwater to. there is nitrate and other chemicals down into the valley. contaminated groundwater in danger's bio topes it's meant to sustain. where the ground water is clean it feeds bio tubes rich in biodiversity. lakes. read beds. woodlands and also manmade lakes. such as old gravel pits as they fill up with water life returns. to. a young great crested green biz looking for food. it find