A B S T R A C T
The long spined sea urchin Diadema antillarum was an abundant grazer on Caribbean coral reefs, until
1983–1984, when densities were reduced by ~98% during a region wide die-off. Since then, there has been very
little natural recovery of the species and interest is growing in applying aquaculture as a tool for population
enhancement. In this study we optimized a new shaker bottle cultivation method for D. antillarum. The method
was tested in a series of experiments by culturing D. antillarum from egg to juvenile in the Netherlands as well as
the USA. Larvae were cultured in standard 1-L glass reagent bottles, suspended by gentle constant movement on
an orbital shaking table and fed with either the microalgae Rhodomonas lens or Rhodomonas salina. Effects on
larval growth and survival were evaluated for different microalgal feeding concentrations, larval densities, and
culture temperatures. Larval density and growth were measured twice a week over a period of up to 56 days.
Larvae grew significantly faster on a higher feeding concentration up to 90,000 Rhodomonas sp. cells mL
As I compose this message in 2022, reflecting on Reef Renewal Bonaire’s accomplishments during 2021, and during its first ten years of operation – I find it impossible not to be captivated by the impact that RRFB’s work has had on the shores of Bonaire and Klein Bonaire. For the diver and snorkeler, this work is now easy to see - acres of restored Staghorn corals, stands of majestic Elkhorns thriving and spawning, and providing habitat for a teeming biodiversity of reef life. If you have been lucky enough to tour the Jeff Davis Memorial dive site, just a few yards off Bonaire’s northern coast, you get a sense of what years of hard work and actively managed, successful restoration work can achieve on Bonaire. When RRFB started, these accomplishments were the dream of our Board of Directors, and specifically of our founding President, Martien Van der Valk. As I assume the role of President in 2022 from Martien, I want to take this opportunity to thank him for his hard work, his broad vision, his get-things-done attitude, and for his ability to assemble the diverse team that has executed on behalf of Bonaire’s coral reefs for the past decade. From the beginning, Martien insisted that this vision could not succeed if it was the initiative of a single dive operation or resort. Rather, the whole of Bonaire needed to embrace the restoration vision for RRFB to succeed. Today, RRFB boasts more than 9 dive operators and resort partners who work together on the mission of protecting, restoring, and giving the reefs of Bonaire a helping hand. Together with the Bonaire government, hundreds of volunteer divers and donors, the Bonaire Tourism Board, STINAPA, DCNA, WWF, and other key island partners, the work of RRFB can truly be categorized as a whole, island-wide initiative. Martien helped define RRFB’s “Secret Sauce” – focus on practical goals that are informed by science but made successful and sustainable by a powerful engine of cooperation between local businesses, government, NGOs, volunteers, and the dive community. As we move forward into 2022 and our next decade, we are setting some very ambitious goals, but we will be guided by Martien’s recipe and his standards as we move forward. Our second secret – in this case, our Secret Weapon - is our Chief Operating Officer, Francesca Virdis. From day one of RRFB, she has been making RRFB’s ambitious vision a reality. She has tirelessly led RRFB’s efforts, pushing it forward in the water, in the lab, and with the scientific community. You will see the impressive results of Francesca’s and her team’s work in this report on our activities in 2021 – but know that RRFB is just getting started. Yes, we will grow more and get more corals in the water but are also looking to significantly scale our outplanting efforts, to push restoration science with new partnerships and new techniques (including building Bonaire’s first full-featured coral Wet Lab), and to continue the push to make Bonaire the global Center of Excellence for coral reef restoration. Thank you to all our partners, donors, and volunteers. As a team, we will continue to execute for Bonaire’s coral reefs and their biodiversity.
David J. Fishman President, RRFB Board of Directors
Using cryopreserved reproductive cells of elkhorn corals, researchers have crossbreed individuals from Florida and Puerto Rico with those of Curaçao in an important first step to creating more heat tolerant populations. The goal is to increase genetic diversity within at-risk populations of corals to help build resilience for future generations.
Genetic evolution allows entire populations to adapt, over many generations, to their local environments. However, environmental conditions are now changing at an accelerated rate, and in some cases, outpacing the ability of species to adapt. This is where Assisted Gene Flow (AGF) comes into play; this conservation intervention involves directly introducing genetic diversity into at-risk populations. In other words, researchers can now influence the reproductive process of threatened species in order to introduce new genetic diversity and thus facilitate faster evolution.
Elkhorn coral. Photo credit: Hans Leijnse
Corals are excellent candidates for the Assisted Gene Flow technique, especially the IUCN “critically endangered” elkhorn coral (Acropora palmata). Estimates place the decline in their populations around 95% since the 1980s. Further, they’ve struggled to keep up with changing water conditions and have documented reproductive issues. Mature corals are difficult to relocate for the purposes of AGF and coral gametes (reproductive cells) lose viability within a few hours. Researchers have therefore used cryopreservation to achieve AGF in this species.
Within the region, there are two distinct populations of elkhorn coral, one from the northwestern Atlantic and one from the Caribbean. A central, mixed zone exists near Puerto Rico. Over time, these populations have evolved to their unique thermal and oceanographic environments.
A recently published report highlighted the successful demonstration of using AGF to fertilize elkhorn corals. This research was a collaborative effort by CARMABI, Smithsonian Conservation Biology Institute, Penn State University, Florida Aquarium Center for Conservation, and Mote Marine Laboratory. Using cryopreserved sperm from eastern and central Caribbean (Florida and Puerto Rico) elkhorn corals, researchers were able to fertilize eggs from western Caribbean (Curaçao). By mixing these genetic pools, researchers may be able to accelerate region-wide adaptations to climate change.
Elkhorn coral. Photo credit: Duncan MacRae
Future of Conservation
In addition to achieving the highest ever survival rate for elkhorn coral juveniles, these researchers were able to generate the largest living wildlife population ever created from cryopreserved cells. This research proved the viability of using cryopreserved genetic material to increase genetic diversity. The future of coral conservation will require innovative techniques, such as AGF, to help keep pace with the accelerated changed due to climate change. By identifying and cryopreserving genetic material for threatened corals, crossbreeding with more tolerant populations may be the key to preserving these species in the future.
To read the full report, please use the DCBD link below.
Article published in BioNews 48
University of Applied Sciences Van Hall Larenstein and Wageningen University and Research recently conducted a comparative study of artificial reefs within the Caribbean. This study provides new insights into the impacts of these structures on local marine life and neighboring ecosystems and highlight the need for comprehensive monitoring and integration into marine management plans.
Photo credit: Rudy Van Geldere
Since the 1960s, artificial reefs have been placed around the Caribbean for tourism, to aid in improving fish stock, providing coastal protection and for scientific research. Unfortunately, there has been limited research to fully understand these reefs’ impact or compare artificial reefs to their natural neighbors. Researchers debate whether artificial reefs actually improve fish populations by encouraging increased reproduction or whether they are merely attracting fish from nearby reefs. Understanding how artificial reefs affect local fish populations and neighboring reefs will be critical in implementing meaningful conservation strategies in the future.
A new study conducted by University of Applied Sciences Van Hall Larenstein and Wageningen University and Research within the AROSSTA (Artificial Reefs on Saba and Statia, www.hvhl.nl/arossta) project aimed to evaluate the ecological effects of artificial reefs within the Caribbean. To do so, 212 different artificial reefs were analyzed based on reef type, location, deployment year, purpose, material, ecological development and fisheries management status.
The results proved very insightful. It was determined that the three most common purposes for artificial reefs were to serve as new dive sites (41%), for research (22%) and to support ecosystem restoration (18%). In addition, they found metal and concrete to be the most widely used materials. They also found a number of factors which could help bolster fish populations, such as reefs which more complex geometries and those placed in areas of dense seagrass.
This study also found that of all the artificial reefs, only 38 are located within marine protected areas which prohibit fishing. This means that over 80% of all artificial reefs are fishable. This is especially true for the Southern and Southwestern Caribbean Including Aruba, Bonaire and Curacao) where 100% of the reefs are within legal fishing zones. As artificial reefs attract part of their marine organisms from surrounding habitats, intensive exploitation by fishers can adversely affect the fish stocks in the surrounding area and thus counteract any potential ecosystem benefits.
Photo credit: Mark Vermeij
Effective marine conservation will require additional information on the impacts of artificial reefs on these local environments. The benefits of increased fish biodiversity and populations could be quickly undone by overfishing within the same area. The authors therefore conclude that the current management status of most artificial reefs in the Caribbean is a threat for its fish stocks. If implemented properly, artificial reefs could be a critical tool for future conservation efforts. Therefore, this study concluded that artificial reefs should be carefully monitored and integrated into future marine management plans.
To find out more, you can read the full study by clicking the DCBD link below.
Article published in BioNews 46
Fundacion Parke Nacional Aruba (FPNA) is proud to be hosting its first Coral Reef Monitoring Workshop this week, together with trainers – marine biologists Tadzio Bervoets from the Dutch Caribbean Nature Alliance (DCNA) and Roxanne-Liana Francisca from STINAPA Bonaire. Participants include representatives from FPNA, JADS, ScubbleBubbles, Caribbean Lionfish Alliance (CLA), Aquawindies and the Directorate of Nature and Environment (DNM).
During this four-day workshop, the participants – all certified divers – will be trained as data collectors following standard coral reef monitoring practices as described by the Global Coral Reef Monitoring Network (GCRMN) and the Atlantic and Gulf Rapid Reef Assessment (AGRRA). Besides being trained in monitoring criteria, techniques and protocol, participants will also be trained in fish, invertebrate, coral recruits (baby coral), algae, coral disease, and invasive species identification – which are a crucial part of monitoring the health of coral reefs.
Coral reefs are ecosystems with possibly the highest biodiversity and unlike anything else on the planet. Apart from being incredibly varied and beautiful, and hosting an array of amazingly interesting life forms, coral reefs are essential to the economy of Aruba. Coral reefs protect our coasts from storms and are a nursery and home to numerous species that are vital to our fisheries. Coral reefs and their specialized fish also provide for Aruba’s beautiful white sandy beaches that tourists worldwide come to enjoy. However, coral reefs and their inhabitants are increasingly being threatened by coastal development, marine and coastal recreation, maritime activities, extractive activities, and land, air and marine pollution, and other impacts.
FPNA’s interim Marine Park Manager Sietske van der Wal is excited to finally start with data collection. “FPNA manages four Marine Protected Areas (MPAs) that are collectively known as Parke Marino Aruba. We are the only island within the Kingdom not yet structurally monitoring the health of our coral reefs and with this workshop we will now acquire the skills to do so ourselves.”
After this workshop, FPNA – together with its partners – will be conducting coral reef surveys every two years at representative locations in order to assess the state of Aruba’s reefs, compare data over time and adapt management accordingly. Data will be shared with DCNA, GCRMN and others to be able to follow trends at a national, Kingdom and regional level. The data acquired through these surveys will also be incorporated into the management of Parke Marino Aruba.
FPNA appreciates and thanks all facilitators and participants for their support in making this workshop possible and a success – be it financially, by supplying equipment and transport, or by devoting their time and effort.
Watch here the live version on 24ora: https://fb.watch/5itHHQyI9c/
Article published in BioNews 42
There is almost no systematic information about the state of marine ecosystems in Aruba. A recent report commissioned by the United Nations Development Program (Pantin 2011) also noted an almost complete lack of information on Aruba’s ecological resources, carrying capacity, limits of acceptable change and the existing level of environmental stress. The Government of Aruba therefore aims to create an assessment program to monitor the status and changes in the reef communities along its coastline. CARMABI, a Curaçaoan foundation specializing in tropical marine research, was selected to conduct the baseline assessment in collaboration with the Scripps Institution of Oceanography (U.S.A.) and the Global Coral Reef Monitoring Network (U.S.A.).
The dire state of coral reefs demands a rapid increase in the scale and efficiency of coral restoration methods in addition to mitigating local and global stressors. Larval propagation can provide vast numbers of coral propagules from an individual spawning event and increased genetic diversity in restored populations. The conversion of embryos collected from wild, broadcast-spawning populations to settlers that can be outplanted to the reef is a key component of this production process. We present preliminary results on settlement yield (i.e. % embryos converted to settled polyps on outplantable substrates) following in situ mass culture in floating mesocosms (Coral Rearing In-situ Basins, or CRIBs; 5.6 m3 volume, 5.4 m2 surface area) that can be implemented independent of land-based facilities. Ten trials over 2 years were conducted in three locations using five Caribbean broadcast-spawning species. Embryos were added at different stocking densities and settlement was scored 2–4 weeks after fertilization. Two trials failed, resulting in no effective settlement, but the remaining eight trials resulted in between 1% and 11% settlement yield (overall mean 5.3%) and 77–100% of substrates exposed to larvae acquired settlers (average production: 700 substrates trial−1). Parallel land-based trials showed a similar range (<1–14%) and mean (3.6%) settlement yield over nine trials. These values are also similar to the previously published lab and field-based trials using Pacific Acropora spp. Continued optimization of CRIB design and execution is expected to improve consistency, overall yield, and efficiency in the production of sexual propagules for restoration.
The presence of associated endofauna can have an impact on the health of corals. Duringfieldwork on the southern Caribbean island of Curaçao in 2021, the presence of an unknown coral-dwelling worm snail was discovered, which appeared to cause damage to its hosts. A study of photoarchives revealed that the species was already present during earlier surveys at Curaçao since 2014and also in the southern Caribbean island of Bonaire in 2019. It was not found in St. Eustatius, anisland in the eastern Caribbean, during an expedition in 2015. The vermetid snail was preliminarilyidentified asPetaloconchussp. Its habitat choice resembles that ofP. keenae, a West Pacific coralsymbiont. The Caribbean species was observed in 21 host coral species, more than reported for anyother vermetid. BecausePetaloconchussp. is a habitat generalist, it is possible that it was introducedfrom an area with another host-coral fauna. The unknown vermetid is considered to be cryptogenicuntil future studies reveal its actual identity and its native range.
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.