Banc d'Arguin National Park as grey heron ("Ardea cinerea monicae") and Eurasian spoonbill ("Platalea leucorodia balsaci") and western reef heron ("Egretta gularis") (IUCN, 1987). For marine mammals, endangered species can be seen here all-year round; for example, Mediterranean monk seals, Atlantic humpback dolphins and bottlenose dolphins. Other species can be seen here are orca, the killer whales, pilot whales, Risso's dolphins, dolphins (common, rough-toothed). Fin whales and harbor porpoises are also known to visit the area. Possibly, highly coastal whale species such as North Atlantic right whales, now-extinct Atlantic gray whales were used to be seen here as well. Other baleen whales possibly occur
Channel types discussed above), rapid/plane bed, step-pool and cascade unit morphologies. Channel types A wide variety of river and stream channel types exist in limnology, the study of inland waters. All these can be divided into two groups by using the water-flow gradient as either "low gradient channels" for streams or rivers with less than two percent (2%) flow gradient, or "high gradient channels" for those with greater than a 2% gradient. Low gradient channels of rivers and streams can be divided into braided rivers, wandering rivers, single thread sinuous rivers (meandering), and anastomosing rivers. The channel type developed depends on stream