Three species of mangrove trees exist in the region: red (Rhizophora mangle), black (Avicennia germinans), and white (Laguncularia racemosa), although all are from different families.[67] All have the same characteristics: they are tolerant of salt, brackish, and fresh water; they grow in oxygen-poor soil; and they can survive drastic water-level changes.[68] Black and white mangroves excrete salt from under their leaves, and red mangroves filter the salinity of sea water. All species are integral to coastline protection during severe storms. Red mangroves, for example, have far-reaching roots that trap sediments. The trees not only stabilize coastlines, but add land as more sand and decaying vegetation is trapped in the root systems. All three mangroves also absorb the energy of waves and storm surges.