Today was dedicated to the habitats of Hol Chan Marine Reserve. We began with an early dive among the mangrove forests that provide a nursery to most of the fish and invertebrate species that make up the barrier reef ecosystem. Snorkeling silently through a shallow mangrove creek, we spied snappers, angelfish, grunts, shrimps and a solitary batfish, whose pectoral fins act like tiny arms as he scoots along the nutrient-rich muddy bottom.

Mangroves are extremely important to the health of tropical ecosystems, serving many critical functions. In addition to their role as a breeding ground for reef species, they provide shelter to juveniles of many species, protect shorelines from storm surge and erosion, and filter sediments and nutrients from the land that would otherwise harm the reef.…