Coral reefs

Abstract

Coral reefs are one of the most biodiverse yet threatened ecosystems on the planet. Our understanding of what contributes to a coral reef’s resilience to adapt to global and local threats is not well established. Thriving reefs in close proximity to anthropogenic impacts indicate there are opportunities for improved understanding of the underlying factors that influence the ability of some coral species to withstand environmental stressors and changing oceanographic conditions. Research suggests that resource availability and a coral’s trophic strategy can improve a coral’s tolerance to environmental stressors. Such discoveries have already been made, but the effects of resource availability on heterotrophic coral species have been minimally explored in the Caribbean; a region that has suffered substantial declines in coral health and cover–. Regardless of these declines, Curaçao, an island in the Southern Caribbean, possesses uncharacteristic coral diversity and cover for the region. One of the most abundant species covering the Curaçao reef tract, Madracis mirabilis, is largely heterotrophic in its feeding strategy. The growth and distribution of this species was tracked across 7 sites spanning approximately 40 kilometers along natural and anthropogenic gradients of nutrients in Curaçao. Our findings suggest that the highest growth and percent cover of M, mirabilis, can be found in regions with the highest exposure to anthropogenic nutrient loading. These data provide insights into how some corals may be better adapted to changing environmental conditions and degradations in water quality

Researchers from University of Amsterdam and CARMBABI Foundation implemented 3-dimensional reef surveying techniques to improve representation of species found within hidden cavities previously overlooked by 2D methods. 12 sites along the coast of Curacao were selected and analyzed. Improved surveying techniques will increase overall understanding of the complexities of these vital ecosystems.

Photo Source: Niklas Kornder

Coral reefs are one of the most diverse ecosystems on the planet.  Coral’s beautiful skeletal structure plays an important role in providing reef habitat, nursery and hunting ground while also protecting coastal zones.  Climate change continues to be a significant threat to these areas, making the need for accurate mapping and surveying techniques vital to researchers’ ability to detect change. Traditional mapping techniques use a 2D approach to project surface cover estimates throughout a 3D structure.  Unfortunately, this technique misses hidden habitats, such as overhangs and cavities, which can result in an under representation of biomass estimates.

Photo Source: Eric Mijts

2D versus 3D

New research from the University of Amsterdam and CARMBABI Foundation compared 2D versus 3D survey techniques. Traditionally, organism abundance was calculated as the percentage of projected reef cover.  Previously, this was done by 2D surveys, however a new strategy hopes to improve on this technique through the combination of photograph analysis, diving surveys and computer modeling. Researchers surveyed 12 coral areas on the island of Curacao, then compared 3D benthic community estimates against traditional 2D projected surface cover analysis.

The Results

During this research, scientists found that while using 2D techniques, the relative contribution of organisms which grow vertically (gorgonians and massive sponges) was up to two times and 11 times lower, respectfully, than their contribution to reef biomass.  In addition, hidden areas represented nearly half of all total reef substrate, meaning two thirds of all coralline algae and almost all encrusting sponges are not included within traditional surveying techniques.

Using a variety of different metrics, this research presents adjustments to current monitoring techniques, highlighting the importance of evaluating the ecological contributions of previously disregarded or underrepresented species.  These metric conversions can be used to complement traditional survey techniques to provide improved estimates for biovolume, biomass and element composition (stocks of organic carbon and nitrogen) within coral reef communities.

Implications

Photo source: Francesco Ungar

Understanding the true composition of coral reefs is vital for designing and implementing effective conservation strategies. Coral’s unique ability to create complex habitats is vital to maintaining high community diversity and abundance in shallow water environments.  It is estimated that nearly 75-90% of coral reef ecosystems are hidden under the surface skeleton.  This means that for every m2 that can be seen, there is up to 8m2 of additional habitat underneath. This study suggests that 2D approaches may be useful to produce relatively fast estimates of reef ‘health’ but a 3D approach is needed to understand coral reef’s true composition.

https://www.dcbd.nl/document/implications-2d-versus-3d-surveys-measure-a...

Article published in BioNews 47

Manmade structures such as seawalls, breakwaters, and jetties are increasing in frequency in marine coastal environments. Overtime, these structures are unintentionally recruiting marine life such as corals, resulting in the formation of artificial reefs. A recent study in the Caribbean has revealed how the biodiversity on these artificial structures compares to natural reefs.

Coral reefs are visually very aesthetic, but above all they play a central role in the ocean. Coral reefs support over 800,000 marine species and supply numerous ecosystem goods and services. Yet sadly, corals are threatened by a combination of global climate change and local human activities such as fishing, shipping and coastal development. Natural recovery is too slow, so active restoration efforts are crucial to prevent the loss of our coral reefs.

CORALS UNDER THREAT

One method of coral reef restoration is the construction of artificial reefs. Artificial reefs come in various forms. Some are designed and deployed specifically to enhance marine life. Others, such as shipwrecks and urban structures –including jetties, seawalls and breakwaters– recruit marine life unintentionally. With increasing coastal development, the frequency of urban structures in the marine environment is increasing, yet marine communities on urban structures receive less attention in scientific research.

This old artificial reef was visibly manmade with smooth basalt blocks cemented together (Source: Naturalis Biodiversity Center)

Filling this gap, a team of researchers explored the biodiversity of urban structures at St. Eustatius, an island of the Caribbean Netherlands. Their findings are published in the scientific journal Marine Pollution Bulletin. The team consists of Claudia Hill from the University of Groningen and Myrsini Lymperaki from the University of Amsterdam, under the supervision of professor Bert Hoeksema, who is affiliated with Naturalis Biodiversity Center and the University of Groningen.

A NEW HOME FOR MARINE LIFE

The island of St. Eustatius, popularly known as ‘Statia’, is located in the eastern Caribbean and is a special municipality of the Netherlands. The island is steeped in history, having changed hands between numerous European empires and having thrived as a port of trade in the 17th and 18th century. Today St. Eustatius is much quieter, though traces of the past like remnants of ancient piers and jetties remain in the coastal water. “These ancient structures shelter a new home for marine life”, tells Claudia Hill, first author of the article. “With corals and other benthos living on the remains, altogether forming an artificial reef”, she continues.

This natural reef was partly biogenic and located on top of a rough lava underground. It supplied a variety of microhabitats in the form of crevices and overhangs.

ARTIFICIAL VERSUS NATURAL REEF

The research team compared the biodiversity on the artificial reef to that of a natural reef nearby. “We found a considerably higher biodiversity on the natural reef, with a wider range of species, a higher density of organisms, and different dominating species”, explains Hill. “We concluded by the greatly differing communities on each reef that artificial reefs can not serve as surrogates for natural reefs.” The researchers highlight, however, that the main cause for biodiversity differences lies in the deviant structural features on the reefs. The natural reef exceeds the artificial reef in microhabitats like crevices and overhangs that are beneficial to the growth of marine life.

What I personally found most surprising, is despite the artificial reef being centuries old, the cover and abundance of reef organisms is still not comparable to that on the natural reef.  But it is important to note, that whilst the artificial reef did not host an identical community to the natural reef, it still serves as a healthy and diverse reef in its own right.

-Claudia Hill

Therefore, there is still a place for artificial reefs in conservation work, as they serve to enhance the marine life of the local area. “Artificial reefs provide a promising outlook for the future of coral reefs, yet a precautionary approach must be taken to prevent any unwanted consequences, such as the invasion of non-native species.”

MORE INFORMATION

• Curious about further details of this study? Read the full publication in Marine Pollution Bulletin.
• For further details about the study, please contact Bert Hoeksema and Claudia Hill.

Text: Claudia Hill, University of Groningen, Naturalis Biodiversity Center
Photos: Naturalis Biodiversity Center

https://www.dcbd.nl/document/centuries-old-manmade-reef-caribbean-does-n...

Article published in BioNews 45

Benthic cyanobacterial mats, at low cover, are an important benthic component of coral reefs, but have recently drastically proliferated on reefs worldwide. To better understand the factors that are driving this proliferation, we first must understand the identity of, and the interactions between, the microorganisms that build these mats. In a recent study published in Science of the Total Environment, researchers from Florida State University used next-generation DNA sequencing to explore the total species diversity of a benthic cyanobacterial mat sampled from the island of Bonaire. They found that coral reef cyanobacterial mats are cooperatively built by multiple species of microorganisms spanning all domains of life, and likely rely on this diversity to exploit environmental changes and proliferate. These data can be used to develop mechanistic hypotheses about what factors are most important in controlling the growth of coral reef benthic cyanobacterial mats.

A benthic cyanobacterial mat bloom (yellow) at Salt Pier, Bonaire, reaching near 100% cover of the benthos. This sequencing data will help scientists better understand how environmental factors interactively drive massive bloom events, such as the one pictured here. © Ethan Cissell

The rise of cyanobacterial mats

Cyanobacterial mats are naturally present at low abundance on coral reefs (~1% cover), and are thought to be critical in supplying bioavailable nitrogen to the reef environment that supports the growth of other benthic taxa such as coral. Recently, however, the abundance of cyanobacterial mats has expanded to cover ~20% of many Caribbean reefs, with massive blooms sometimes reaching close to 100% cover of the benthos. The increase in cover of benthic cyanobacterial mats poses numerous threats to overall reef health. To understand how different environmental factors are driving the rise of cyanobacterial mats, it is important to characterize the identity of the species that build these mats, and to understand the unique functional role of each mat community member.

DNA sequencing

To characterize the total diversity of benthic cyanobacterial mats, the team utilized a type of genetic sequencing known as shotgun metagenomic sequencing for its first ever application on a coral reef benthic cyanobacterial mat sample. In contrast to other sequencing methods that specifically target the DNA of only certain target species in a sample, this method instead sequences all of the DNA from a sample, and allows scientists to characterize all organisms in a sample, including viruses. The team sequenced 2 samples in this way – 1 taken from the growing edge of a cyanobacterial mat and 1 taken from the interior of that same cyanobacterial mat.

Species diversity

Shotgun metagenomic sequencing revealed that representative species from all domains of life can be found in coral reef benthic cyanobacterial mats, including members of domain Archaea, Bacteria, and Eukarya. The Florida State University team found that cyanobacteria were present at only 47.57% relative abundance in the mat samples, alongside other bacteria present at a relative abundance of 45.78%. Viruses, including viruses that can infect and kill bacteria called bacteriophages, were also present in the sampled mat at a relative abundance of 0.08%.

A benthic cyanobacterial mat (red) overgrowing an Orbicella annularis colony at Oil Slick Leap, Bonaire. Overgrowth interactions, such as the one pictured here, are detrimental to coral health, and will become more common as benthic cyanobacterial mats proliferate. © Ethan Cissell

Functional diversity

The team also found that the sampled mat possessed a diverse set of metabolic functions, including numerous cooperative functions for living as a coordinated community. The sampled mat community possessed numerous functions for the efficient utilization and storage of environmental phosphorous and nitrogen, both potentially limiting to the growth of cyanobacterial mats. Interestingly, the team also found evidence for multiple different pathways of nitrogen cycling, including the removal of bioavailable nitrogen in a process termed denitrification, that suggests the paradigm of cyanobacterial mats as an important nitrogen source to coral reefs should be revisited.

Future directions

Ongoing work by Cissell and McCoy seeks to characterize the dynamics of benthic cyanobacterial mats across multiple spatiotemporal scales using novel map-based tracking performed from May – July 2019 at Angel City, Bonaire. Additionally, Cissell and McCoy are using shotgun sequencing of both the DNA and RNA of multiple cyanobacterial mats to better understand daily cycles of mat community members, and their expressed functions. Combining an understanding of spatiotemporal variability in mat functions with a robust characterization of the persistence and volatility of cyanobacterial mats across multiple scales will facilitate rigorous tests of factors controlling mat abundance on Caribbean reefs.

More information

Cissell, E.C., McCoy, S.J. 2021. Shotgun metagenomic sequencing reveals the full taxonomic, trophic, and functional diversity of a coral reef benthic cyanobacterial mat from Bonaire, Caribbean Netherlands. Science of the Total Environment 755: 142719. https://doi.org/10.1016/j.scitotenv.2020.142719.

https://www.dcbd.nl/document/shotgun-metagenomic-sequencing-reveals-full...

Article published in BioNews 42

At Van Hall Larenstein University of Applied Sciences (HVHL) in Leeuwarden, the sea urchin Diadema antillarum has been cultivated to help restore the coral reefs around Saba and St. Eustatius (Caribbean Netherlands). The first young urchins bred in Leeuwarden were released on March 24th to the Rotterdam Zoo (Diergaarde Blijdorp). The ultimate goal is to also breed this species on Saba in order to give the sea urchin populations there a helping hand. These sea urchins keep algae growth under control, giving corals more room to grow. During this project, researchers worked closely with students from the Coastal and Marine Management program.

Repopulation of sea urchins for reef conservation

Diadema antillarum sea urchins were the main grazers of Caribbean coral reefs until over 95% of sea urchins were killed by an unknown disease in 1983. Without sea urchins grazing, algae became the dominant group on the coral reef, outcompeting coral. Today, nearly 40 years after their mass death, sea urchins have still not recovered. HVHL is working with the RAAK PRO Diadema project (2019-2023) along with project partners for the restoration of this species on Saba and St. Eustatius (Caribbean Netherlands).

©Tom Wijers

Long awaited breeding method

For the past 40 years, researchers have been trying to breed Diadema in captivity, but unfortunately have only had limited success. Breeding as been found to be very difficult. Larvae of this type of sea urchin float along sea currents for the first 50 days of their life and are sensitive to water quality and nutrient availability. However, in 2020 researchers and students from HVHL in Leeuwarden managed to develop a method for stable and consistent breeding of young Diadema.

Rotterdam Zoo

It is difficult to transport these animals on a large scale to Saba or St. Eustatius, so the first group of young urchins will find a nice new home in the Rotterdam Zoo starting on March 24th. The next step will be to breed urchins on Saba so that they can be released into the wild, strengthening the populations and helping to restore the coral reef.

More Information

For more information about this project, visit the HVHL website. For a video about this project, please visit our YouTube channel. Follow the project on Facebook for updates.

Article published in BioNews 42

Informational material for regulations outlined in the Convention of International Trade of Endangered Species of wild flora and fauna (also known as the CITES) has been developed for residents and tourists on Bonaire, Saba, and St. Eustatius. Posters, signs, and brochures have been made in four languages (Dutch, English, Papiamentu, and Spanish) by the Dutch Caribbean Nature Alliance (DCNA) by order of the Ministry of Agriculture, Nature and Food Quality (ANFQ).

Image credit: © Deviate Design & Mercedes Madriz

In advance of the return of tourists, these materials will be placed at the airports and ports, and at the government and customs offices, nature park management organizations, diving schools, and hotels throughout the Caribbean Netherlands. In this way, DCNA and ANFQ will work to raise awareness about the protected status of flora and fauna in the Caribbean Netherlands, such as orchids and corals, and the rules concerning the removal of these species.

Conservation of biodiversity

The islands of the Caribbean Netherlands have a rich biodiversity. Many species are endemic to one (or more) of the islands, meaning they cannot be found anywhere else in the world. Almost 200 species living in the wild in the Caribbean Netherlands are protected by CITES. The list includes turtles, iguanas, orchids, cacti, whales, rays, and bird species. Furthermore, the corals these islands are known for, living or dead, are also protected under CITES and therefore cannot be removed. In addition to the CITES regulations, stricter local rules and measures may also apply.

What does this mean in practice?

Exporting living or dead species included on the CITES list to another country without a CITES permit – including between the Caribbean Netherlands to the Netherlands and vice versa – is prohibited. These regulations apply whether the species or objects are taken as a gift or for one’s own use, and include items such as orchids, cacti, corals, seahorses, turtles, sharks, iguanas, and birds. These regulations also apply to parts or products made of or from these species, such as food products, exotic leatherware, wooden sculptures, ornaments, musical instruments, or local medicines. In certain cases, exporting species or objects is prohibited altogether. Violation of these regulations can lead to penalties and/or legal action.

Check in advance: is it protected?

The mere fact that something is for sale or that you found it on the ground or in the sea, does not mean that you are allowed to take or travel with it. When in doubt as to whether you can take a species (or a part of a product made of or from this species), you can contact the local CITES authority with the National Office of the Caribbean Netherlands (Rijksdienst Caribisch Nederland, RCN), the customs authorities, the public entity, or the local management organization of the protected nature area.

What is CITES?

CITES is the Convention of International Trade of Endangered Species of wild flora and fauna which regulates and, if necessary, prohibits the trade or removal of a species for the benefit of conserving it in the wild. More than 37,000 flora and fauna species are currently protected under the CITES convention. A CITES permit is required for the trade of these species. In some cases, the trade is prohibited altogether if the species is seriously threatened with extinction. These regulations do not only apply to the respective plants and animals but also to products made of or from these species.

# # #

Check the CITES information for the Caribbean Netherlands online:

https://www.dcbd.nl/document/cites-communication-materials-bes

For more information about CITES:

• www.RijksdienstCN.com
• www.RVO.nl/CITES
• www.cites.org

Article published in BioNews 41

Coral reef ecosystems

Tropical coral reefs are among the most productive and biologically diverse ecosystems found on earth (Odum and Odum 1955; Connell 1978; Moberg and Rönnbäck 2003). Although these reefs only cover 0.1 – 0.5% of the ocean floor they provide a home to almost one third of the marine fish species and other marine biota (Mcallister 1991; Spalding and Grenfell 1997; Spalding et al. 2001). Like rainforests, their terrestrial equivalent, the three-dimensional habitat complexity underpins the biological success of coral reef systems (Connell 1978; Grigg et al. 1984; Reaka-Kudla 1997). This structural framework is primarily provided through the precipitation of vast quantities of calcium carbonate by scleractinian corals (Goreau 1959b; Goreau and Goreau 1959; Smith and Kinsey 1976). Basic growth of coral skeleton forms the fundament of the reef and facilitates complex ecosystem functioning and niche partitioning to harbour an exceptional heterogeneity of associated biota (Connell 1978; Graham and Nash 2012; Kennedy et al. 2013; Newman et al. 2015). Ancillary to the inexpressible biological value, millions of people worldwide rely in some way on the services provided by coral reefs, most notably for nourishment, but also for services associated with tourism and coastal protection (Costanza et al. 1997; Moberg and Folke 1999; Moberg and Rönnbäck 2003). By increasing frictional dissipation of wave energy, the complex physical structure created by corals protects coastal shorelines from erosion. This has allowed humans to settle and develop coastal areas throughout the tropics. Yet, coral reefs are at present ubiquitously under pressure due to a variety of stressors associated with increased anthropogenic activity on a global and local scale.

The marine environment is continuously exposed to change, but currently this change is more and more the result of human actions (Harvell et al. 1999; Derraik 2002; Orr et al. 2005; HoeghGuldberg and Bruno 2010). The stress exerted by the natural and anthropogenic induced changing global environment works in synergy with stressors that act on a finer spatial scale. Factors such as the overharvesting of fish, pollution, eutrophication, coastal development and the introduction of invasive species can locally trigger shifts in community composition and trophic hierarchy (Hughes 1994; Hughes et al. 2003; Pandolfi et al. 2003; Hughes et al. 2007; Hughes et al. 2017). By destabilising ecosystem functioning and interactions between key species, these stressors reduce reef resilience and therewith the capacity of coral reefs to cope with globally induced sea surface temperature anomalies or ocean acidification (Pandolfi et al. 2003; Bellwood et al. 2004; Hughes et al. 2017). Reefs in the wider Caribbean region seem particularly vulnerable to anthropogenic impact (Jackson et al. 2014). By large this can be ascribed to increased local pressures associated with the unprecedented human population expansion in the region. Since the 1950s, the total population in the Caribbean has more than doubled (United Nations, Department of Economic and Social Affairs, Population, Division, 2015). Natural biological and hydrological conditions are also less favourable compared to, for instance, the Indo-Pacific region (Roff and Mumby 2012). Biological diversity in the IndoPacific exceeds 10-fold the diversity found in the Caribbean (Spalding et al. 2001; Hoeksema et al. 2017), implying limited functional redundancy in the latter (Bellwood et al. 2003; Bellwood et al. 2004; Jackson et al. 2014). In addition, the quality of Caribbean surface water is significantly impacted by discharge from major South-American rivers like the Amazon and Orinoco as well as the North-American Mississippi river. The residence time of the polluted and eutrophic water from these rivers, combined with run-off and sewage water from the numerous islands is relatively long in the Caribbean Sea due to its distinct basin-like morphological and hydrological features (Roff and Mumby 2012). As a consequence of the rapid anthropogenic alteration of the marine environment we now see an ecological degradation of Caribbean coral reef habitats that has not occurred for over 200.000 years (Pandolfi and Jackson 2006).

Regional Context:

The Caribbean Region represents only 1% of Earth’s marine surface but hosts 10% of the world’s coral reefs, including fringing reefs, which are most common, barrier reefs such as the Mesoamerican Reef, which is the largest barrier reef in the Western Hemisphere, bank reefs, patch reefs, and a few atolls.

Caribbean shallow and mesophotic reefs are characterized by relatively low coral species diversity (70 hard coral species including two Acroporid species: Acropora palmata and A. cervicornis) and high levels of endemism, making them unique among the world’s reefs.

The physical geography of the Caribbean region is also complex with continental coasts (north, central, and south America), large continental islands (Greater Antilles), numerous small sandy islands (The Bahamas), volcanic islands (most of the Lesser Antilles), and coral islands (some Lesser Antilles islands).

The Caribbean is politically and culturally diverse with 30 sovereign states (continental and insular) and 16 European overseas territories or outermost regions (British, Dutch, and French), and considerable economic disparities between nations (e.g. per capita Gross Domestic Product in the USA was USD63,544 compared with less than USD1,200 in Haïti)1 .

About 70% of people in the Caribbean live near the coast. Indeed, Caribbean economies depend heavily on coral reefs and associated ecosystems (seagrasses and mangroves) for recreation and tourism (e.g., sandy beaches, snorkeling, and SCUBA diving), livelihoods, food (e.g., fishes, queen conch, lobsters), and other social, cultural, and economic benefits. Socio-economic monitoring (SocMon) in the Caribbean region, carried out largely according to the GCRMN SocMon protocol, is in use as an approach for coral reef managers and provides valuable insights on how coastal communities value and depend on coral reefs. Thus, SocoMon assessments have been conducted for almost 20 years in the region, including a series of workshops conducted recently beginning in 2016 (Jamaica) to the most recent in 2019 (MesoAmerica) by SPAW-RAC and supported by a NFWF-funded project to develop and refine a set of integrated coral reef monitoring guidelines that explicitly include human dimensions characteristics. For a detailed analysis of the SocMon Caribbean socio-economic assessments, please see the Global SocMon report that is forthcoming in 2022.

Socio-economic monitoring is important in order to understand the human interactions with coral ecosystems so that we can mitigate negative effects to coral reefs while promoting positive benefits that reefs provide [http://socmon.icriforum.org/]. SocMon has been part of the wider GCRMN effort since 1997 and was developed with the intent for socio-economic monitoring to complement biophysical monitoring. While SocMon data are not included in the present analysis, future work should and will seek to integrate Caribbean node socio-economic data with biophysical data.

The Caribbean is divided into 10 Marine Ecoregions of the World (MEOW) Ecoregions2 that were grouped into five subregions for the analyses underpinning this report (Tab. 1). There are coral reef marine protected areas (MPAs) in many countries in the Caribbean, as well as MPA networks such as MPAConnect and CaMPAM. The MPAs are usually small and generally located in nearshore areas. Efforts to support coral monitoring and capacity-building are underway with support from partner organisations such as the UN Environment Programme/ Cartagena Convention Secretariat, the National Oceanic and Atmospheric Administration (United States of America), the Gulf and Caribbean Fisheries Institute, the Specially Protected Areas and Wildlife protocol and its regional activity center (SPAWRAC), through regional projects and via multi-national programmes. MPA financing, enforcement, fisheries management, monitoring and communications are among the top management capacity building needs identified by coral reef managers to implement effective marine protection.

Abstract

Ecosystems are under pressure worldwide, due to both natural and anthropogenic stresses. Stresses on ecosystems can cause a decline in biodiversity, a loss of habitat and a deterioration in ecosystem services. To avoid further pressure on ecosystems caused by advancing economic development, new infrastructure projects should be integrated into the ecosystem. Environmental Impact Assessments (EIAs) are now mandatory for projects that are likely to have significant environmental effects. EIAs have primarily focused on mitigating negative impacts. However, recently new design philosophies have emerged such as ‘Engineering with Nature’, ‘Working with Nature’ and ‘Building with Nature’ which also focus on promoting positive impacts.

Constructively realizing nature-inclusive projects is complicated due to involving stakeholders with differing perspectives. Therefore, in an integrated approach towards new marine infrastructure development, the next step is to promote constructive collaboration between stakeholders to systematically investigate the nature-inclusive potential of infrastructure. This thesis describes a proposed strategy for doing so, within the context of nearshore infrastructure development located in or nearby coral ecosystems. The focus is on how nature-inclusive potential of new marine infrastructure might be maximised, taking into account the local ecosystem.

The aim of this research is to find an optimal approach to develop coral-inclusive infrastructure. This is done by structuring the required discussions between stakeholders considering socio-economic, ecological and engineering perspectives regarding the nature-inclusive design potential of new marine infrastructure. For this purpose, a method was developed that proposes a step-by-step strategy to promote constructive collaboration between relevant stakeholders, consisting of the following five steps:

1. project description, outlining the basic challenge at hand

2. project location analysis, involving a systematic assessment of the relevant ’natural system’ as well as the ’anthropogenic system’

3. Development of marine infrastructure design applications, involving an inventory of project elements that can have negative or positive effects on the overall ecosystem

4. inventory and ranking of potential measures, objectively outlining feasibility and potential effectiveness of measures and design modifications

5. summary of sustainable design recommendations, leading to a systematic ranking of potential measures proposed to support further decision making.

We have investigated the effectiveness of the systematic method, by applying it to a case study in Sint Eustatius that investigates whether the intended extension of a breakwater in Sint Eustatius can be designed as a coral-inclusive project. Sint Eustatius was chosen because Rijkswaterstaat offered research opportunities on location. In an ideal case, the use of long-term consistent data maps the natural factors over a longer period of time. This provides greater certainty of results and recommended actions. However, the values that were reported for the Sint Eustatius case were not derived from long term systematic data collection. Furthermore, the substrate from the existing breakwater looks to be promising for coral recruitment. However, there is not a lot of coral development evident on the existing breakwater. Possible negative factors hindering coral development on the existing breakwater are: 1) poor water quality; 2) high hydrodynamic circumstances with high wave action in shallow waters which limits the type of coral species; 3) inconsistent larval supply through ocean currents.

Coral reef connectivity seems sufficient and potential substrate is already present in the existing breakwater. Extension of the breakwater will lead to substrate increase which could improve the chance for coral recruitment in a hurricane-risk area as Sint Eustatius. A valid next step that could be proposed to aid a better understanding of this habitat is to invest in an extensive and dedicated data gathering campaign.

In conclusion, the main improvements derived from the application of the systematic approach for nature-inclusive potential for infrastructure projects are:

• providing an overview of the steps required to create coral-inclusive infrastructure,

• instigating the investigation of the status or the possibilities for coral development,

• assisting ecologists and engineers to structure the discussion on coral-inclusiveness,

• lowering the barrier to use (new) design philosophies,

• and stimulating coral development and decreasing negative effects by providing design recommendations.

Bringing stakeholders with different perspectives together in one nature-inclusive project plan remains challenging. Environmental data can play a role in arriving at a realistic approach supported by ecologists and civil engineers to realize nature-inclusivity for infrastructure. This requires knowledge, money and time and could provide insight into the threats and opportunities. The systematic approach, derived in this thesis, has been proven to support stakeholders in assessing the nature-inclusive potential of marine infrastructure.

Abstract

Intentional and unintentional physical contact between scuba divers and the seabed is made by most divers and multiple times per dive, which often results in damage to corals and other marine life. Current efforts to reduce reef contacts (e.g., voluntary dive operator recognition programs and voluntary dive standards) can be effective, but lack sufficient incentive structures for longterm compliance. In their current capacity, these programs fail to reduce reef contacts to tolerable levels. Regulatory policies can facilitate pervasive and permanent shifts in human behavior, but have been underutilized to change unsustainable underwater norms. Most coral reefs open to recreational diving lie within territorial waters of individual countries, and many already have existing forms of protection with legislation that can be easily modified. Successful policy precedents in Marine Protected Areas (e.g., bans on underwater glove use) and elsewhere (e.g., antismoking laws in public spaces and legislation enforcing seat belt use) demonstrate the largely untapped potential of using effective governance to change destructive diving norms for good. To reduce intentional reef contacts, policy-makers can enact regulations in MPAs directly banning all contact between divers and the seabed. To reduce unintentional contacts, policy-makers can create policy safeguards that preempt such occurrences (e.g., requiring divers to keep a certain distance from the seabed). Crucially, such policies will need accompanying formal and informal enforcement measures that are equitable, effective, and efficient to motivate compliance and effect lasting behavior change. Having a robust, well-enforced, regulatory framework to tackle both types of reef contacts lends credence to the efforts of existing conservation programs, and is key to permanently changing divers’ underwater attitudes and fostering sustainable scuba diving behavior to the benefit of all.