Acropora tenella coral

Acropora tenella is a species of coral likely found in the Coral Triangle area (the Philippines to Timor Leste and east to the Solomon Islands). There are also confirmed records of this species in southern Japan, Micronesia, and the Marshall Islands. Colonies of Acropora tenella have horizontal, plate-like colonies with flattened branches that usually have a central ridge. Colonies are cream colored with blue or white tips.

Under the Endangered Species Act, NOAA Fisheries must list threatened and endangered marine species regardless of where they are found. Acropora tenella is listed as threatened throughout its range under the ESA.

Learn more about Acropora tenella (PDF, 3 pages) 

Acropora tenella forms flat, plate-like colonies with flattened branches. These colonies are made up by many individual polyps that grow together. Colonies are cream colored with blue or white tips.

Acropora tenella gets food from photosynthetic algae that live inside the coral's cells. It also feeds by capturing plankton with its polyp’s tentacles.

Acropora tenella is likely found in the Coral Triangle area, which stretches from the Philippines to Timor Leste and east to the Solomon Islands. It has also been seen in southern Japan, Micronesia, and the Marshall Islands. Acropora tenella occurs on lower reef slopes and shelves in water 130 to 230 feet deep and is well-suited to calm, deep conditions.

Acropora tenella can live up to hundreds of years. Scientists believe that this species is hermaphroditic, meaning that it produces both eggs and sperm.

Acropora tenella reproduces by “broadcast spawning” eggs and sperm into the water column. Fertilized eggs develop into larvae. These larvae begin to grow and form new colonies once they settle on a hard surface.

Climate Change

Climate change is the greatest global threat to corals. Scientific evidence now clearly indicates that the Earth's atmosphere and oceans are warming, and that these changes are primarily due to greenhouse gases derived from human activities.  As temperatures rise, mass coral bleaching events and infectious disease outbreaks are becoming more frequent. Additionally, carbon dioxide absorbed into the ocean from the atmosphere has already begun to reduce calcification rates in reef-building and reef-associated organisms by altering seawater chemistry through decreases in pH. This process is called ocean acidification. 

Diseases

Diseases can cause adult mortality, reducing sexual and asexual reproductive success, and impairing colony growth. Coral diseases are caused by a complex interplay of factors including the cause or agent (e.g., pathogen, environmental toxicant), the host, and the environment. Coral disease often produces acute tissue loss. 

Land-based Sources of Pollution

Impacts from land-based sources of pollution—including coastal development, sewage, deforestation (clearing a wide area of trees), agricultural runoff, and oil and chemical spills—can impede coral growth and reproduction, disrupt overall ecological function, and cause disease and mortality in sensitive species. It is now well accepted that many serious coral reef ecosystem stressors originate from land-based sources, most notably toxicants, sediments, and nutrients.

Unsustainable Fishing

Fishing, particularly unsustainable fishing, can have large scale, long-term ecosystem-level effects that can change ecosystem structure from coral-dominated reefs to algal-dominated reefs (“phase shifts”). This results from the removal of fish that eat algae and keep the reef clean to allow for space for corals to grow. 

Small Population Size

The Acropora tenella population is small and colonies are rare throughout its range. These factors makes reproduction more difficult and increase the risk that the population will continue to decrease. 

Habitat Degradation

Corals are threatened by habitat degradation. Activities that may degrade habitat include deforestation, urbanization, and mining activity. These activities can reduce the amount of habitat available and deliver chemicals that are toxic to corals.