Eckrich, C.E.

STINAPA report

Mass coral bleaching is becoming more frequent and widespread and poses a major threat to coral reefs worldwide. Mass coral bleaching is a response to thermal stress triggered by high Sea Surface Temperatures (SSTs) or ultraviolet radiation attributed to changing regional and global climate patterns. Since 2016, STINAPA Bonaire has surveyed the severity of coral bleaching in the Bonaire National Marine Park at 10 sites on the leeward coast. Each year, corals exhibited signs of thermal stress including paling, partial bleaching, and fully bleaching, but no mortality. Since 2016, the year with the lowest percentage of corals affected was 2018 (9%) and the year with the highest percent of corals affected was 2020 (61%). Corals deeper in the water column were more susceptible to thermal stress in all years, but susceptibility trends by site were not consistent throughout the study. While addressing the global-scale causes of coral bleaching is daunting, STINAPA Bonaire monitors the severity of coral bleaching and helps develop local management strategies that may improve the resistance and resilience of coral reefs in the Bonaire National Marine Park to climate change.

Raw photo material of the 2019 reef survey using the GCRMN method.

The 12 survey sites lie within the Bonaire National Marine Park, which surrounds the island from the high water mark to a depth of 30 meters. To maximize comparability across the region, GCRMN data was collected solely from forereef habitats at depths ranging from 8 – 15 meters. Sites included the industrialized harbor area along with sites with perceived lower anthropogenic influence on the north and south ends of the island. For each site 5 transects were surveyed. Photographs were taken along the 5 transect lines set for counting fish, capturing 15 images per transect line.

Please contact the DCBD administratorfor access to the raw digital photographs.

Raw data of seagras monitoring on Lac, Bonaire. 

At 49 locations 6 square meter quadrants are investigated. The coverage per seagrass species is measured per quadrant using a 10 by 10 cm grid. 

Observed species:

• Thalassia testudinum (Turtlegrass, Species code: Tt) - IUCN Red List
• Syringodium filiformi (Manatee Grass, Species code Sf) - IUCN Red List
• Halodule beaudettei (Shoal grass, Species code Hy - IUCN Red List
• Halophila stipulacea (Species code: Hs) - IUCN Red List
   
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Please contact STINAPA for more information

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At the end of 2016 / beginning of 2017 a coral bleaching event was reported on Bonaire. Directly after the event quadrant photographs were taken to inventory the impact of the bleaching event, at:

• Playa funchi
• Rei Willem Alexander, no-dive reserve
• Karpata
• Oil slick leap
• Reef scientifico
• Playa lechi
• Invisibles
• Vista blue
• Mi Dushi
• Ebo's special

The photographs have been analysed to report on impacted species and magnitude. 

Please contact the DCBD administrator or STINAPA for access to the raw digital photographs.

Event: BirdsCaribbean 21st International Conference, Topes de Collantes, Cuba, 13-17 July, 2017

Abstract in scientific journal or proceedings

Five species of terns are reported breeding in Bonaire from April to August. For three years, the species Sternula antillarum, Sterna hirundo, Thalasseus maximus, Thalasseus eurygnatha and in 2017 Sterna dougalli were monitored in southern Bonaire during the breeding season, with the objective of suggesting management actions and increasing reproductive success. Monitoring results showed that the main threat is the presence of feral cats. The hatching success for Thallasseus species and Sterna species was relatively similar over the years. However, there are indications that hatching success for Sternula antillarum colonies on roads has increased from 17% (2014) to 36% (2016) after a pilot program for management of invasive predators began in 2015. On the other hand, native predators on artificial islands have had negative effects, suggesting that the creation of spaced islands is important to avoid large concentrations in small areas that favor predation.

Findings:

• Ramicrusta overgrows 14 of Lac’s species of scleractinian corals including Acropora, Agaricia, and Diploria, as well as three species of gorgonians.
• Ramicrusta grows upward from the base of coral and causes the death of grown tissues.
• Complete overgrowth by the crustose calcareous algae may happen after several months.

Management Recommendations:

N/A

An encrusting red alga (Ramicrusta sp., Peyssonneliaceae) present in Lac Bay, Bonaire, overgrows and kills corals and other sessile organisms. Living coral tissue comprises 7.2 % of the benthic composition of the shallow reef, while Ramicrusta sp. covers 18.7 % of the substratum. Of 1374 coral colonies surveyed, 45.8 % were partially overgrown by Ramicrusta sp., with P. porites, P. astreoides and M. complanata being the most susceptible to overgrowth. Mean Ramicrusta sp. maximum overgrowth rates ± SD were 0.08 ± 0.05 mm d-1, 0.07 ± 0.03 mm d-1 and 0.06 ± 0.02 mm d-1 for M. complanata, P. porites and P. astreoides, respectively. None of the 71 coral recruits surveyed were growing on Ramicrusta sp. Ramicrusta sp. is an immediate threat to corals, reduces the area of suitable substratum for coral settlement and may have the ability to influence coral species composition.