In recent years, sea otters have began inhabiting upper reaches of the slough in greater numbers. This change in habitat use has had multiple unexpected effects on the slough including recovery of the eel grass beds (otters eat crabs which eat nudibranchs that keep the surface of the Zostera free from algal fouling) and, more recently discovered, they may prevent the erosion of the banks by reducing numbers of the super abundant Pachygrapsus crassipes that erode the mud banks with their "crab condos". The effect of sea otters on coastal habitats are just one example of the important ecosystem services provided by predators. The old paradigms focusing on a negative predator effect on prey populations are short-sighted and are slowly being overwhelmed by evidence to the contrary.