Final answer:
Freshwater organisms, like those in lakes and rivers, have adaptations such as excreting dilute urine to manage osmosis. They belong to diverse ecosystems that are challenged by human activity and biological homogenization, calling for novel conservation measures.
Step-by-step explanation:
Freshwater Organisms and Their Ecosystems
Freshwater organisms live in environments where they are surrounded by water, such as lakes, rivers, streams, and ponds. Despite the abundance of water, these organisms face the challenge of osmoregulation because they are constantly in danger of having water rush into their cells due to osmosis. One of the key adaptations they have developed is the ability to excrete dilute urine, thereby regulating solute concentrations within their bodies. Freshwater environments only make up about 1.8 percent of the Earth's surface, yet they are biodiversity hotspots, supporting a wide range of life including fish, amphibians, reptiles, insects, phytoplankton, fungi, and bacteria.
Moreover, aquatic organisms in freshwater ecosystems can be categorized into three groups: plankton, nekton, and benthos, each with unique modes of movement and habitats. However, the dispersion of these organisms is restricted by terrestrial barriers and oceans. Human activities have bridged some of these barriers, inadvertently or purposely introducing new species into different regions, which can lead to ecological homogenization and sometimes endanger native species.
Despite the adaptations of freshwater organisms, many of them face threats from human alterations of ecosystems, introductions of non-native species, and competition for water resources. Amid these challenges, novel ecosystems are emerging that integrate native and non-native species into new biological assemblages, requiring innovative conservation strategies to ensure the survival of native species.