Using Habitat Quality Indicators to Evaluate the Success of Freshwater Habitat Improvements

Despite freshwater ecosystems being critically important, they have been severely degraded such that freshwater biodiversity losses have been widely documented. To mitigate this loss, many attempts to improve freshwater habitats have been undertaken using various techniques such as those related to restoration and rehabilitation. Assessing whether these efforts are effective is necessary to not only support habitat and species recovery, but also to inform future initiatives. However, such initiatives are challenged by funding constraints, timeline limitations, and lack of standardized evaluation methods, resulting in a need to define relevant monitoring strategies. High quality habitat is essential for population persistence making habitat quality a relevant indicator of the success of freshwater habitat improvement efforts. Additionally, habitat quality indicators are more relatable to the habitat itself and thus more indicative of long-term success than metrics currently being used. Herein we describe key indicators of habitat quality and illustrate why such measures are useful assessment tools for evaluating the success of freshwater habitat improvements. Based on our synthesis, we outline methods that can be used to describe habitat quality for animals such as metrics of behaviour, bioenergetics, ‘omics’, food webs, and biotic indices. We also outline challenges associated with assessing habitat quality and make suggestions to help overcome them. We then share considerations for evaluating the success of habitat improvement initiatives using habitat quality indicators including how to define success, select appropriate spatial and temporal scales, and consider the tiers of evidence provided by the different indicators. To conclude, we present two case studies to further illustrate the practical application (and challenges) of using habitat quality indicators to assess the effectiveness of freshwater habitat improvement initiatives.