Acropora prolifera on Barbados fringing reef

Observations 2015-2019 and ongoing.

In March of 2015, I observed two specimens of Acropora palmata while snorkelling in the Seaward Slope zone of Vauxhall Reef in the Recreational Zone of the Barbados MPA; then in deeper water (Reef Front Zone) I observed a small bed of Acropora cervicornis. Later I decided to do a transect* from shore-seaward across the whole reef to characterize it & to my surprise, I observed an area just behind the reef crest with a large colony of Acropora prolifera - a hybrid between A palmata and A cervicornis. Then I criss-crossed the nearshore area finding a total of 18 separate colonies of A. prolifera, several of them aggregations of two or more individual colonies. *The "transect consisted of photos taken in sequence; the approx locations were estimated by reference to Google Earth images of the reef combined with my on-the-ground descriptions

My interpretation is that there was likely one initial colony of A. prolifera (a hybrid between local A. prolifera and A. cervicornis), the others developing asexually by fragmentation. I looked at nearshore reef for approx. 0.5 km to the south and 1 km to the north and did not observe any other areas with A. prolifera.

A comprehensive survey of Acroporoid corals on the west coast of Barbados was conducted from June 13th to
August 22nd 2015 by R. MacLean & H.A. Oxenford - CERMES Technical Report No 80 "Mapping the return of acroporid corals on fringing reefs along the west coast of Barbados" by R. MacLean & H.A. Oxenford: "A total of 707 colonies, consisting of both A. palmata and A. prolifera, were found...The vast majority were A. palmata and easy to distinguish from the other two species, with their characteristic palmate growth forms... A total of 21 colonies were positively identified as the hybrid, A. prolifera. Most of these (14 colonies) were found in a small area of Vauxhall (reef 34) and were easy to distinguish from the two true species (A. palmata and A. cervicornis) since they had the ‘bushy’ morphology typical of hybrid crosses where the egg comes from A. cervicornis...These Acropora prolifera colonies indicate sexual reproduction between A. palmata and A. cervicornis and although no A. cervicornis colonies were found on the fringing reefs surveyed in this study, several colonies are known to exist in the deeper patch reef area immediately seaward of some of the fringing reefs (e.g. Vauxhall reef, see annotated photographs of D. Patriquin at: http://versicolor.ca/reef/).

So evidently, the only A. cervicornis that have been seen in recent years are those I observed in March of 2015 (it was very common when I was a student at the Bellairs Research Institute 1966-70).

This iNaturalist project includes photos of all colonies/specimens of A. prolifera, A. palmata and A. cervicornis that I observed in March of 2015. I will be adding further photos of these and additional specimens observed during the winter months 2016, 2017, 2018 and 2019. The 2015 photos were posted initially in a personal Google Album; a link to that album and some further info about the area is given at http://versicolor.ca/reef

Note: I don't understand why, but the location map showing the locations of all observations mis-places a number of observations even though they show up correctly when you bring up an individual observation. less ↑