Final answer:
Low dissolved oxygen levels can signal excessive algal growth that blocks sunlight, vital for kelp photosynthesis, and can also result from increased water temperature due to global warming. Warmer waters reduce oxygen solubility, creating stressful conditions for marine life and can alter ecosystem species composition, affecting kelp forests.
Step-by-step explanation:
Changes in dissolved oxygen levels in water have significant impacts on aquatic ecosystems, particularly on kelp growth. Kelp, like all photosynthetic organisms, requires light to thrive. If dissolved oxygen levels are low, this can indicate the presence of excessive algal growth, which can form dense layers on the water's surface and block sunlight needed for kelp forests. Additionally, low oxygen levels can result from increased water temperature, which is often associated with global warming. Warmer water holds less oxygen, which can stress or even kill marine life, including kelp which forms integral parts of the ecosystem.
Furthermore, increased decomposition of organic matter fueled by higher temperatures and eutrophication leads to more consumption of dissolved oxygen, worsening the hypoxic conditions. Hypoxia can lead to drastic alterations in the species present in an ecosystem, as organisms that require more oxygen may not survive, while others that can tolerate lower oxygen levels may proliferate. This shift can have a cascading effect, including on kelp, as they are foundational species that provide habitat and food for a variety of marine life. Therefore, maintaining adequate levels of dissolved oxygen is essential for the health and sustainability of kelp forests and their associated ecosystems.