Final answer:
The third phase of succession in lakes and wetlands is called the climax stage, where the community reaches a stable and mature state, supporting a diverse range of species.
Step-by-step explanation:
The third phase of succession in lakes and wetlands is known as the climax stage. In this phase, the community of plant and animal species reaches a stable and mature state. The vegetation is well-established, and the habitat can support a diverse range of species. This stage typically occurs after several intermediate stages of succession, where different species gradually replace each other until the final climax community is established. For example, in a wetland, the climax stage may be characterized by the presence of tall, woody plants like cattails or reeds, and a variety of animals that rely on these plant species for shelter and food.