Menhaden are crucial not only because of their keystone species-status in the food web, but also because of their ecological services.  The way Menhaden filter feed on phytoplankton helps to mitigate toxic algal blooms.  These algal blooms, which are often detrimental to a number of fish, bird, and marine mammal species, create hypoxic conditions.  The phytoplankton being preyed upon are photosynthetic organisms, converting sunlight into energy which is then transferred to Menhaden and then to bigger species of fish or other larger marine organisms such as birds or mammals.  The consequence of this behavior is that if Menhaden are eliminated or significantly decreased, there are limited means of energy transfer among trophic levels - making Menhaden a true keystone species with ecological services that are invaluable to humans.