Oceanic manta rays (Mobula birostris) are large pelagic planktivores that are threatened globally by targeted fisheries and bycatch. While studies of oceanic mantas have increased substantially in the past decade, major knowledge gaps remain in their basic biology, ecology and life history. The juvenile stage in particular is virtually unstudied, as juvenile oceanic mantas are rarely observed in the wild and are known primarily from fisheries and captive individuals. Here, we present evidence suggesting that Flower Garden Banks National Marine Sanctuary (FGBNMS) is an important habitat for juvenile manta rays. Recent genetic evidence indicates that both oceanic mantas and a proposed third manta species (Mobula cf. birostris) are present at FGBNMS. Size estimates of mantas sighted at FGBNMS over 25 years of monitoring efforts indicate that 95% of individuals are smaller than the size at maturity for male M. birostris, and 80% are smaller than the size at maturity for M. alfredi. Photographic records of juvenile males with undeveloped claspers further corroborate these findings. Temporal patterns of use and the prevalence of juveniles suggest that this region may serve as nursery habitat for M. birostris and M. cf. birostris. Further research is necessary to determine the importance of the region to juveniles of each species, as well as long-term patterns of habitat use and residency.

No abstract

East Flower Garden Bank (EFGB) and West Flower Garden Bank (WFGB), part of Flower Garden Banks National Marine Sanctuary (FGBNMS) in the northwestern Gulf of Mexico, support tropical coral reefs that exhibit over 50% living coral cover. These reefs have been monitored annually since 1989, and in 2016 were exposed to higher than normal seawater temperatures leading to a severe bleaching event. Corals at EFGB and WFGB showed no signs of bleaching until September 2016, occurring later in the year compared to other reefs in the Caribbean region. Coral bleaching and subsequent recovery at each bank were documented through a time series of repetitive photographs within previously established long-term monitoring stations. Preceding the event, mean live coral cover within monitoring stations was collectively 64 ± 2%. Prior to signs of bleaching from July to September 2016, seawater temperatures on the reef were above 30°C for a total of 36 d at EFGB and 21 d at WFGB. By October 2016, 67 ± 5% of the coral cover within EFGB monitoring stations and 25 ± 3% within WFGB monitoring stations exhibited signs of bleaching or paling stress, with dissimilarities in the amount of bleaching most likely due to significant differences in thermal profiles between banks. Significantly increasing long-term trends for daily mean seawater temperature indicate that temperatures on the banks have become warmer over time, and calculated bleaching threshold curves suggest that more than 50 d above 29.5°C would initiate a bleaching year at EFGB and WFGB. Even though recovery within monitoring stations at both banks was documented with no significant declines in mean coral cover from 2016 to 2017 (64% and 62%, respectively), it is likely FGBNMS will be subject to additional and more frequent bleaching events in the future as ocean temperatures continue to rise.

No abstract

Since 1989 a federally supported long-term coral reef monitoring program has focused on two study sites atop East and West Flower Garden Banks in the northwestern Gulf of Mexico. We examined 25 yr of benthic cover data to provide a multi-decadal baseline and trend analysis of the community structure for this coral reef system. Despite global coral reef decline in recent decades, mean coral cover at East and West Flower Garden Banks was above 50% for the combined 25 yr of continuous monitoring, and represented a stable coral community. However, mean macroalgal cover increased significantly between 1998 and 1999, rising from approximately 3 to 20%, and reaching a maximum above 30% in 2012. In contrast to many other shallow water reefs in the Caribbean region, increases in mean macroalgal cover have not been concomitant with coral cover decline at the Flower Garden Banks.