Complex sentence: The Indian River Lagoon is North America's most diverse estuary, with more than 2100 species of plants and 2200 animals; it includes 35 species listed as threatened or endangered--more than any other estuary in North America.
Split into simpler sentences: The Indian River Lagoon is North America's most diverse estuary, with more than 2100 species of plants and 2200 animals. The lagoon contains 35 species listed as threatened or endangered--more than any other estuary in North America.