coral reef

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.  

 The Study 

 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 

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

Future Conservation

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.

https://www.dcbd.nl/document/artificial-reefs-caribbean-need-comprehensi...

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

Background
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.).

Abstract

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.

Full text available here:  Settlement yields in large‐scale in situ culture of Caribbean coral larvae for restoration - Miller - 2022 - Restoration Ecology - Wiley Online Library

Abstract:

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.

Supplemental Materials.

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.

After news was received that the Netherlands Antilles' largest and as yet
almost unspoiled lagoon would be involved in development plans, a
scientific survey was organised for obtaining new data on the present
condition of Lac, Bonaire.
The field work took place between i and 28 August, 1967, by Dr. P. J.
Roos, Amsterdam - who had already studied the coral fauna of Lac
in 1965 - and between 7 August and 23 September by Dr. P. WAGENAAR
HUMMELINCK, Utrecht, who first visited the lagoon in 1930. Roos did
most of the underwater work whereas HUMMELINCK collected biological
specimens from about 60 localities. The survey was initiated by the
Foundation for Scientific Research in Surinam and the Netherlands
Antilles (STUDIEKRING) and was financed by the Netherlands Foundation
for the Advancement of Tropical Research (WOTRO). The material is
being studied in the Zoological Laboratory of the State University at
Utrecht, in cooperation with specialists; most of the results will be
published in the Foundation's "Studies on the Fauna of Curacao and
other Caribbean Islands".
The Lac covers about 8 km^; of this one third is mangrove and shallow
mud flats (Figs. 3-5, 12). The transparency of the water is striking,
compared with that of other inland bays in the Lesser Antilles. Dearth of
nutrients may cause the absence of mangrove-oysters and other mollusks
known to occur in abundance in other mangrove lagoons, and also the
scarcity of balanids and other animal species which are common in
similar Caribbean environments.
Lac is separated from the sea by a barrier of coral debris; a shallow
flat of white sand occurs inshore (Figs. 3-4, 5, 12). The basin has vast
7"Aa/assj'a flats, whose shallower parts may be very muddy, often with
abundant Ha/twerfa. Syrtngorfjum grows near the entrance of Lac and
in other sandy areas. .4uraiwwV/ea is common in several inlets, where it
may grow in profusion. i?w/>£ia is found in creeks and ponds of high
salinity. .Di/j/an/Wa has been collected only once (Figs. 7, 12, 52).
More data on the fauna and flora are shown in Figs. 8-11. The distribution
of the small form of Afe/ongena we/ongena appears to have been
much larger some 30 years ago. CAfowe cawee/Za/a was not found in Lac
recently but it was abundant a few thousands years ago when the lagoon
extended further inland (Figs. 11, 51). It is likely that the fauna of Lac
has become poorer in recent times. The big heaps of S/tt>m6«s £tgas have
not visibly increased in size during the last thirty years (Figs. 8, 35-36).
During the last century the landscape has changed considerably.
Formerly the broad sandy barrier which separates the basin from the
mangrove-flat in the north (Figs. 12, 17-18, 24, 26, 46-47) had several
large openings through which the water could circulate. Afterwards part

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.

The Saba Bank is a large (ca 2400 km2 ) submerged carbonate platform of 15-40m depth rising up from 800-1000m depth and fringed with coral reefs. It extends into a carbonate peninsula of ca 80m deep (Luymes Bank) which is pockmarked by sinkholes. More than twenty drowned sinkholes were distinguished in this peninsula based on available bathymetric data. Diameters of sinkholes vary from 70 to 1100 m and depths ranges between 10-300m. The area of the Luymes Bank with sinkholes is ca 66 km2 . During the NICO cruise in 2018 two sinkholes were visited in the Luymes Bank. In one of the two shallow sinkholes, which were only briefly explored with camera’s in 2018, we found peculiar pillar-like, probably calcium carbonate accretions with diameters of 40-60cm and protruding up to 1m from the sandy bottom. Pillars were found to stand neatly ordered on the bottom at a depth of ca 110 m. Based on the pink color on top, pillars look like features formed by crustose coralline algae of unusual size and density, almost in a stromatolitic fashion. In the second sinkhole such pillar-like structures were not found. Very little is known about these structures, their distribution and the conditions under which they are formed. Moreover, no information is available of the benthic communities and environmental conditions in the very deep sinkholes of more than 150m m depth. Therefore, the sinkhole expedition was completely dedicated to the sinkholes and the platform in which they occur (Luymes Bank).

The aims of the expedition were:

1. To study the distribution and environmental conditions (e.g. nutrients O2, particulate organic matter, water movement) of benthic communities on the platform between sinkholes and in the sinkholes with emphasis on areas with regularly distributed pillar-like structures in sinkholes.
2. To take high resolution pictures of the benthic communities with high-resolution camera system and NIOZ video frame in order to describe the benthic communities.
3. To collect bottom samples in order to determine the species diversity of these communities.
4. To collect pillars and assess the species consortia producing the pillars, their life history strategies, accretion rates and stratigraphic history.
5. To survey and investigate the carbonate chemistry of sinkholes of different size and depth and detect the effects of possible stratification in sinkholes.
6. To determine metagenomics and metabolomics in water samples from sinkholes of different size and depths.
7. To investigate Light-Dark shifts in metagenomics and metabolomics in near bottom water samples in relation to nutrients, O2, carbonate chemistry and POM in shallow sinkholes (20- 40m deep) with and without pillar-like structure and the platform community at approx. 80m depth.
8. To collect plankton samples for closer studies of plankton communities over the Luymes Bank

Smalls islands are especially vulnerable to climate change and land  use changes due to the competing needs for limited resources. To support the NEXUS approach we need evidence based monitoring tools that can provide policy makers, conservation managers, entrepeneurs, scientists and the general public with information on the state, pressures and associated changes in the environment. Satellite imagery can provide synoptic information at appropriate
spatial and temporal resolutions that can support evidence based monitoring. Only at very detailed levels information might be added by using airplanes or drones. Remotely sensed information can help to provide information on e.g. land cover and associated dynamics such as urban sprawl, mapping habitats such as mangroves and coral reefs, surveying terrain conditions such as soil moisture conditions and erosion hazards associated within catchments, sea level rise and changing coastlines, and on many aspects of the vegetation (natural and agriculture), such as plant traits, phenology and plant growth. Remotely sensed information can in general make field surveys and monitoring more effective, and can thoroughly support decision making.