User:Betam25/Scarus niger

General
It can be found evenly distributed across the reef flat and slope. The dusky parrotfish often lives in solitude, but males may also live in a small group of mating females. When breeding, the male and female fishes form pairs, and the female lays eggs that are later hatched. The dusky parrotfish is primarily herbivorous, and its main source of food is benthic algae. At maturity, the fish is approximately 230-240mm long and weighs around 240g.

Reproduction
The dusky parrotfish is a protogynous hermaphrodite, as evidenced by instances where a dominant female in a group with only females turned into a male. It undergoes a reproductive cycle that can be defined by the size and appearance of its gonads; upon reaching maturity, the gonads of the fish weigh an average of 2.54 g. After breeding, the gonads regress in size till they weigh an average of 0.37 g. Dusky parrotfishes release one batch of eggs per breeding season.

Feeding Behavior
The dusky parrotfish feeds primarily on algae found on hard substrate and dead coral. It has a relatively fast feeding rate of around 98.9 in 5 minutes in comparison to other parrotfish species; however, at the same time, it has a relatively small bite volume of 0.002 cm3. It contributes very little to bioerosion in comparison to other parrotfish, averaging around 2.5 ± 0.9cm3 per hour. It does not follow any set feeding pattern, but it tends to feed more in the morning and afternoon rather than at midday and sundown.

Marine herbivores like the swarthy parrotfish rely on endosymbiotic microorganisms to digest carbohydrates. In aerobic conditions, bacteria ferments the carbohydrates and produces short-chain fatty acids or SCFAs. First studied in vertebrate herbivores, SCFAs also allow marine herbivores to further digest carbohydrates that were not broken down by digestive enzymes. This process may contribute as much as 30% of the basal metabolic energy needed for the organism. Acetate was the major SCFA found in the plasma of Swarthy parrotfish, ranging from .45 ± .11 mM to 3.80 ± 1.89 mM, suggesting the swarthy parrotfish fishes use microbial digestion.

Ecology
The reef ecosystem may be dramatically shifted in the absence of the swarthy parrotfish. After extreme climate events, like cyclones, subtle reef dynamics change such as grazing by herbivorous fish. In 2011-2012 after severe climate disturbances, grazing by herbivores fish, including the swarthy parrotfish, decreased by over 90%. Although these changes were not visible, they make the reef ecosystem highly unstable and many reefs may be on the verge of collapse. The reductions in grazing can cause algal turfs which are non-palpable to the swarthy parrotfish.

The presence of the swarthy parrotfish in large and small reef communities contributes to diversity and therefore the resilience of the ecosystem.

Distribution
The swarthy parrotfish is not heavily fished and therefore their population dynamics are more likely determined by habitat and recruitment.