Potential use of classical biomanipulation to improve water quality in New Zealand lakes: a re-evaluation

The potential use of fish for biomanipulation to improve water quality of lakes in New Zealand was evaluated in 1998 when various constraints, including those based on the structure of pelagic food webs in New Zealand (few potential grazers, zooplanktivores and piscivores), were identified. Since 1998 increased nutrient loading, deteriorating water quality in more lakes and the wider distribution of non-indigenous fish and Daphnia have occurred throughout New Zealand. In light of these changes, we reassess the potential use of biomanipulation to improve water quality and conclude that, whereas constraints related to implementation and management that were outlined in 1998 still remain, subsequent abiotic and biotic changes, including the spread of non-indigenous species, and the possible use of indigenous mussels have strengthened the potential for the use of biomanipulative techniques in integrated lake-specific programmes to improve water quality in some lakes.