In 2019, a major coral bleaching event affected reefs worldwide, including marginal reefs within the Abrolhos Bank (16°40′–19°40′S, 39°10′–37°20′W), the largest and richest coral reefs in the South ...Atlantic. Between March and May 2019, this area was affected by the strongest heatwave since 1985. The health trajectories of the branching hydrocoral
Millepora alcicornis
and the endemic reef-building coral
Mussismilia braziliensis
were recorded during this thermal stress event. The degree heating week value reached its historical maximum (DHW 19.65), causing bleaching in 100% of
Millepora alcicornis
and 80% of
Mussismilia braziliensis
colonies. Bleached
Millepora alcicornis
were rapidly covered by cyanobacteria, followed by algal turfs and calcareous algae, leading to 90% mortality. Conversely, 90% of
Mussismilia braziliensis
colonies recovered to a healthy state after bleaching. The high post-bleaching recovery capacity and resistance to mortality of this massive reef-building coral suggests these marginal reefs can be resilient to thermal stress events, despite losing structural complexity due to high mortality of branching and less abundant hydrocorals.
Hybridization between sea turtle species occurs with particularly high frequency at two adjacent nesting areas in northeastern Brazil. To understand the outcomes of hybridization and their ...consequences for sea turtle conservation, we need to evaluate the extent of hybridization occurrence and possible deleterious effects in the hybrid progeny. Thus, we investigated the hypothesis of the existence of a new hybrid spot offshore of Brazil's northeastern coast. The Abrolhos Archipelago is surrounded by the largest and richest coral reefs in the South Atlantic and is known to be a nesting site for loggerhead turtles (Caretta caretta). In this study, we performed a multidisciplinary investigation into levels of hybridization in sea turtles and their reproductive output in the Abrolhos beaches. Genetic data from mitochondrial DNA (mtDNA) and six autosomal markers showed that there are first-generation hybrid females nesting in Abrolhos, resulting from crossings between hawksbill males (Eretmochelys imbricata) and loggerhead females, and backcrossed hatchlings from both parental species. The type and extent of hybridization were characterized using genomic data obtained with the 3RAD method, which confirmed backcrossing between F1 hybrids and loggerhead turtles. The reproductive output data of Abrolhos nests suggests a disadvantage of hybrids when compared to loggerheads. For the first time, we have shown the association between hybridization and low reproductive success, which may represent a threat to sea turtle conservation.
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