Environmental Problems, Their Causes, and Sustainability 1

Why Should We Care about Alligators?The American alligator,NorthAmerica’s largestreptile, has no naturalpredatorsCONNECTIONSexcept humans.This species, which has beenaround for about 200 million years,has been able to adapt to numerouschanges in the earth’s environmentalconditions.This changed when hunters begankilling large numbers of theseanimals for their exotic meat andtheir supple belly skin, used tomake shoes, belts, and pocketbooks.Other people considered alligatorsto be useless and dangerousand hunted them for sport or out ofhatred. Between l950 and 1960,hunters wiped out 90% of the alligatorsin Louisiana. By the 1960s,the alligator population in theFlorida Everglades also was nearextinction.People who say “So what?” areoverlooking the alligator’s importantecological role or niche in subtropicalwetland ecosystems. Alligatorsdig deep depressions, orgator holes. These holes hold freshwater during dry spells, serve asrefuges for aquatic life, and supplyfresh water and food for manyanimals.In addition, large alligator nestingmounds provide nesting andfeeding sites for herons and egrets.Alligators also eat large numbers ofgar (a predatory fish) and thus helpmaintain populations of game fishsuch as bass and bream.As alligators move from gatorholes to nesting mounds, they helpkeep areas of open water free of invadingvegetation. Without thesefree ecosystem services, freshwaterponds and shrubs and trees wouldfill in the coastal wetlands in the alligator’shabitat, and dozens ofspecies would disappear.Some ecologists classify theNorth American alligator as a keystonespecies because of these importantecological roles in helpingmaintain the structure and functionof its natural ecosystems. Some sayit can also be classified as a foundationspecies.In 1967, the U.S. governmentplaced the American alligator onthe endangered species list. Protectedfrom hunters, the alligatorpopulation made a strong comebackin many areas by 1975—toostrong, according to those who findalligators in their backyards andswimming pools, and to duckhunters, whose retriever dogssometimes are eaten by alligators.In 1977, the U.S. Fish andWildlife Service reclassified theAmerican alligator from an endangeredspecies to a threatened speciesin Florida, Louisiana, and Texas,where 90% of the animals live. In1987, this reclassification was extendedto seven other states.Alligators now number perhaps3 million, most in Florida andLouisiana. It is generally illegal tokill members of a threatenedspecies, but limited kills by licensedhunters are allowed in some areasof Texas, Florida, Louisiana, SouthCarolina, and Georgia to control thepopulation.To biologists, the comeback ofthe American alligator from nearpremature extinction by overhuntingis an important success story inwildlife conservation.The increased demand for alligatormeat and hides has created abooming business in alligatorfarms, especially in Florida. Suchfarms reduce the rewards for illegalhunting of wild alligators.Critical ThinkingSome homeowners in Florida believethey should have the right tokill any alligator found on theirproperty. Others argue this shouldnot be allowed because alligatorsare a threatened species, and housingdevelopments have invaded thehabitats of alligators, not the otherway around. What is your opinionon this issue? Explain.munity that depend on it for certain services. Accordingto biologist Edward O. Wilson, “The loss of a keystonespecies is like a drill accidentally striking a powerline. It causes lights to go out all over.”What Are Foundation Species? PlayersWho Create New Habitats and NichesFoundation species can create and enhance habitatsthat can benefit other species in a community.Some ecologists think the keystone species should beexpanded to include the roles of foundation species,which play a major role in shaping communities bycreating and enhancing habitat that benefits otherspecies. For example, elephants push over, break, oruproot trees, creating forest openings in the savannagrasslands and woodlands of Africa. This promotesthe growth of grasses and other forage plants that benefitsmaller grazing species such as antelope. It also acceleratesnutrient cycling rates. Some bat and birdfoundation species can regenerate deforested areasand spread fruit plants by depositing plant seeds intheir droppings.Proponents of the foundation species hypothesissay that Paine’s study of the role of the sea star Piasterorchaceus as a keystone species in an intertidal zonecommunity did not take into account the role of musselsas foundation species.http://biology.brookscole.com/miller14149