Large-scale and long-term distribution of corals in the gulf of Mexico and Caribbean Sea of Mexico and adjacent areas: Corals distribution in Mexico and adjacent areas

Abstract

Hard coral distribution varies across temporal and geographical scales. Distribution of scleractinian corals was analyzed in 59 reefs in the Gulf of Mexico and Caribbean Sea of Mexico in two seasons 27 years apart. Data was collected by photography along 20 meter long transects placed at 10 m depth intervals over a 0–50 m depth range. Abundance data was generated by sampling 31 random points in each photographic image. A total of 62 hard coral species were identified. Overall abundance decreased by 67.17% between the two sampling periods. Abundance values were highest at Cozumel Island in the first period and at Chinchorro Bank in the second. Most (91%) of the sampling sites exhibited declines in abundance ranging from 2 to 99.25%. Different scleractinian species experienced declines from 3.72 to 98.7%, although Tubastrea coccinea increased by 16.6% and Porites astreoides by 1430.3%. Based on the Importance Value Index, dominance was highest for Manicina areolata (10.07%) in the first period and Orbicella annularis (10.49%) in the second. Species richness decreased at 67.79% of the sites and diversity at 57.62% of them; however, average diversity values varied minimally between the two periods (3.22–3.14 Bits/Ind.). In both periods, coral species exhibited peaks of higher richness and diversity at the sampled oceanic reefs in the Caribbean Sea. Analysis of site association with the Bray–Curtis index showed strong affinities among sites in the Gulf of Mexico and among those in the Caribbean Sea, although in the latter some differentiation existed between oceanic and coastal reefs. Non-metric scaling analysis showed species spatial distribution to be in well-defined groups that remain intact in both periods.