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The reef crests of the Jardines de la Reina National Park (JRNP) are largely formed by Acropora palmata , but colonies of A. cervicornis and the hybrid A. prolifera are also present. This study shows spatial distribution of colonies, thickets and live fragments of these species in the fore reefs. Snorkeling was used to perform the direct observations. The maximum diameter of 4,399 colonies of A. palmata was measured and the health of 3,546 colonies was evaluated. The same was done to 168 colonies of A. cervicornis and 104 colonies of A. prolifera . The influence of the location and marine currents on a number of living colonies of A. palmata was analyzed. For such purpose, reef crests were divided into segments of 500 m. The marine park was divided into two sectors: East and West. The Caballones Channel was used as the reference dividing line. The park was also divided into five reserve zones. We counted 7,276 live colonies of Acropora spp. 1.4% was A. prolifera , 3.5% A. cervicornis and 95.1% A. palmata . There were 104 thickets of A. palmata , ranging from eight to 12 colonies, and 3,495 fragments; 0.6% was A. cervicornis and the rest A. palmata (99.4%). In the East sector, 263 colonies (3.8% of the total), six thickets (5.8%) and 32 fragments (1%) of A. palmate were recorded. In the same sector, there were 11 fragments (50%) of A.cervicornis and two (2%) colonies of A. prolifera . Health of A. palmata was evaluated as good and not so good in the study area. Health of A. cervicornis was critical and health of A. prolifera was good in all five reserve zones. There was a significant increase in the number of colonies from east to west (Χ2 = 11.5, gl = 3.0, p = 0.009). This corroborates the existence of an important abundance differences between the eastern and the western region of the JRNP. A negative relationship was observed between the number of colonies and the distance from the channel (Χ2 = 65.0, df = 3.0, p < 0.001). The influence of the channel, for the live colonies of A. palmata is greater within the first 2,000 m. It then decreases until approximately 6,000 m, and no significant increase beyond. The orientation of the reef crests significantly influenced the abundance of the colonies (Χ2 = 15.5, df = 2.9, p = 0.001). The results presented here provide a baseline for future research on the status of the populations of Acropora spp., considering that there has been a certain recovery of the species A. palmata during the last 10-16 years. Given the current status of the populations of Acropora spp., conservation actions focusing A. cervicornis should be prioritized., Competing Interests: The authors declare that they have no competing interests.

In the spur-and-groove reefs of the Ecological Reserve Siboney-Juticí (Southeast Cuba) octocorals are one of the predominant components of the sessile fauna. Main objectives of the present paper are characterizing the composition, structure and conservation status of the octocoral communities and assessing on the prevailing environmental conditions in the study area. For data collection, six sampling sites were located every 2-3 km ranging from 12 m to 17 m depth along the spur-and-groove reefs. In each site, 22-26 lm2 quadrants were zigzag arranged every 2 m. The density of colonies was determined per site. The severity degree and predictability of environmental conditions were inferred by using the Heterogeneity and Equitability indexes, respectively. Hydrodynamic stress and the Comparative Pollution Index were also assessed. Current affectations of the octocoral communities were also determined and classified into four main categories: mechanical damage, diseases, predation and invertebrate and macroalgae overgrowth. As a result, 25 species represented by 752 colonies were recorded and Eunicea flexuosa and Gorgonia ventalina were the most abundant. The occurrence of Eunicea succinea forma succinea constituted the first report for Eastern Cuba. Site densities ranged from 3.58 +/- 1.84 to 7.58 +/- 2.16 colonies/m2 and considered from moderate to low. The biggest densities were reported at both sides of the San Juan River mouth. Despite of the composition and structure of the octocoral communities, low to high hydrodynamic stress and low and moderate levels of contamination were inferred, it is likely that these indexes could have been overestimated due to the sensitivity of the indicator species to other factors such as sedimentation. The environmental conditions were mostly favorable and stable. In general, the number of dead colonies was low and mostly caused by the detachment of the substrate and overgrowth of Millepora alcicornis. Injuries were mainly brought about by mechanical damage, followed by coenenchyme loss, predation by Cyphoma gibbosum and macroalgae overgrowth. On the other hand, negative effects by Hermodice carunculata predation, bleaching, Red Band and Black Band Disease were not observed. Among sampled species, G. ventalina colonies were the most severely damaged within the community. As a whole, octocoral communities of spur-and-groove reefs in the Ecological Reserve Siboney-Juticí showed a good conservation status.