Answer:
In a wetland ecosystem:
1- Indicator species: turtles
2- Keynote species: freshwater crayfish
Step-by-step explanation:
A wetland is an ecosystem either covered with water or saturated with water. Examples of plants living in wetland ecosystems include water lilies lotus, trees (e.g., swamp she-oak), mosquito fern, eelgrass (Vallisnaria spiralis), etc. Examples of animals living in wetlands include dragonflies, mosquitoes, alligators, salamanders, snakes, turtles, grouse, plover, etc. Alligators and freshwater crayfish can be considered keystone species because they are fundamental and their presence defines wetland ecosystems (without these species, wetlands would be dramatically impacted). Moreover, turtles can be considered indicator species because their abundance and distribution in a wetland is an indicator of environmental conditions. These animals (turtles) carry around different organisms (e.g., algae) that are eaten by other species (e.g., fish), and thus contribute to the homeostasis of the ecosystem.