soon. Natural warm-water springs face problems from over-pumping of groundwater for human consumption, reduced spring flow, and nutrient pollution. In addition, some springs that were historically accessible to manatees are blocked off by dams or other structures. In areas where manatees lack access to power plants or natural warm springs, they instead seek out natural deep water zones that passively remain above tolerable temperatures. Harmful algae blooms Harmful algae blooms are an additional threat to manatees. Red tide is a common name for algal blooms, deriving its distinctive color from pigmentation molecules in the algae. The blooms produce brevetoxins which are potentially fatal to marine life. Most manatee deaths from red tide occur when manatees inhale the toxins, or ingest the toxins when consuming seagrass, their primary food source. During a 1996 epizootic more than 150 manatees died from red tide exposure. Although manatees can survive exposure to red tide if rescued and rehabilitated in time, researchers fear that there might be long-term effects from sublethal red tide exposure, which can affect the manatee's immune system through reduced lymphocyte proliferation response. In addition to red tide, blue/green and brown algae blooms triggered by excessive nutrient pollution from fertilizer, runoff, and leaking septic tanks can cloud the water. This results in seagrasses dying off since seagrasses and aquatic plants need light to photosynthesize. Manatees in turn may not be able to find sufficient food sources, which can lead to starvation. Manatees have experienced several Unusual Mortality Events (UMEs) over the years, which are usually related to either cold-stress syndrome, or brevetoxicosis from red tide. A current UME is ongoing along the Atlantic coast of Florida and is most likely related to a shortage in food sources. Entanglement, entrapment and ingestion of debris Manatees can easily get entangled in monofilament fishing line, crab traps, and other debris, which can lead to the loss of flippers and severe body wraps. In addition, they may also ingest a variety of debris, such as plastics, cloth, fishing gear, and other items. Manatees can also get crushed by flood control structures and locks and may get entrapped behind weirs or other structures, especially after heavy rainfall. Some manatees have gotten trapped in culverts and pipes and needed intervention. T. m. manatus (Antillean manatee) There is relatively little data on the Antillean manatee compared to its Florida counterpart. Phylogenetic studies on the Antillean manatee have revealed low