TRACKING POLLUTION AND SUBSEQUENT REMEDIATION OF LAKES USING AGREEMENT BETWEEN LIVING COMMUNITIES AND DEATH ASSEMBLAGES OF OSTRACODES

Practical tools to identify habitats impacted by humans and to monitor the progress of subsequent remediation of those habitats are vital for sustainable environmental initiatives. Ostracodes have long been used as reliable sentinels of changes in ancient environments, yet remain little exploited, particularly by conservationists and environmental managers, to track ongoing environmental change. Live/dead agreement of mollusks has proven to be a reliable tools to identify habitats impacted by humans in marine environments. Human impact shifts the presently-living community away from a pre-impact (“pristine”) state, which the dead shells record thanks to their time-averaged accumulation integrating multiple generations. The resulting low live/dead agreement is a reliable marker for human impact, particularly nutrient pollution and over-trawling. Here, we explore the parallel use of live/dead agreement of ostracodes to not only identify environments impacted by humans, but also to signal the long-term success of remediation of lacustrine environments. Low live/dead agreement of lacustrine ostracodes has been shown to be a reliable marker to identify a suite of diverse human impact of varying magnitude and temporal extent in subtropical lakes. Live/dead agreement today is low in Bahamian lakes impacted by heavy metal and nutrient pollution as well as municipal dumping by modern populations. Live/dead agreement is similarly low in subtropical lakes subjected to direct resource exploitation by human populations from the nineteenth century. In temperate Wisconsin, low live/dead agreement of lacustrine ostracodes is also a reliable indicator of nutrient pollution, but previously-impacted lakes subjected to remediation by treatment with alum -KAl(SO₄)₂·12H₂O- to reduce nutrient loads in the 1970s, exhibit high live/dead agreement, like less impacted subtropical lakes. Thus, we have demonstrated that live/dead agreement of lacustrine ostracodes is a reliable tool to 1) identify anthropogenically impacted habitats and 2) signal the success of remediation in similar previously-impacted habitats that is ripe for use by stewards of aquatic resources.