Cladophora, a filamentous green algae commonly found in the Great Lakes and other freshwater bodies, is intricately tied to the occurrence of HABs in those waters. While Cladophora itself is not toxic, its growth can contribute to conditions that facilitate the development of HABs. One of the primary connections lies in the excessive nutrient levels, particularly phosphorus and nitrogen, that fuel both Cladophora and HABs. In nutrient-rich environments, Cladophora proliferates, forming dense mats that reduce water quality and alter aquatic ecosystems (Sampling Cladophora in Lake Ontario). These mats can trap and accumulate phosphorus, creating localized "hot spots" of nutrient concentration (State of the Great Lakes - 2022 Report). When Cladophora decomposes, the nutrients are released back into the water, creating ideal conditions for the development of HABs, especially cyanobacteria blooms (Notable decomposition products of senescing Lake Michigan Cladophora glomerata). Cyanobacteria can produce toxins harmful to both aquatic life and humans (Cladophora in the Great Lakes: Impacts on beach water quality and human health). Thus, the presence of Cladophora can indirectly increase the likelihood of toxic algal blooms.