Environmental conditions in coastal estuaries vary hourly and seasonally. (a) discuss two important causes for the variation in the temperature and/or salinity of an estuary. be sure to include the connection between each cause and temperature and/or salinity. (b) discuss two roles that coastal wetlands play that are ecologically important, and two roles that wetlands play that are economically important. (c) identify and explain three ways in which humans have had a negative impact on or have degraded coastal wetlands. (d) choose one of the negative human impacts you identified in part (c), and explain one environmental policy and one economic incentive that could have prevented it.