Mangrove root survey yields early warning at Playa Honda

The Costa Mar Reef Monitoring Network's July survey at Playa Honda's southern mangrove tract recorded a root-density index of 2.1 on a five-point scale — the lowest reading since the monitoring programme began in 2019. The index measures new prop-root growth per square metre, a standard proxy for juvenile mangrove health.

Network coordinator Elena Vargas said the decline correlates with elevated water temperatures at the Playa Honda station, which have averaged 29.4°C this month — 0.8°C above the July baseline. 'This is not yet a die-off,' Vargas said. 'But it is the kind of signal we are trained to watch.' The network will conduct a follow-up survey in two weeks.