Mangrove Wetland in Southport Broadwater Parklands, Queensland: Ecosystem Functions and Benefits

Introduction

Wetlands, the land that never dries, are the areas having soil or nearby surface covered by water all years or for varying periods in the year (United States Environmental Protection Agency 2017a). According to the World Wide Fund for Nature (2017b), wetlands can be in different forms including marshes, delta, mudflats and so on. While wetlands are generally known as the “kidneys of the Earth”, the United States Environmental Protection Agency (2017b) suggests they can be imagined as a “biological supermarket” as they are one of the most productive ecosystems on the Earth, comparable to rainforests and coral reefs. The Council of the City of Gold Coast (n.d.b) recognises the importance of the wetlands because of their unique functions and services and has been working on the conservation of wetlands on the Gold Coast through redevelopment and community engagement. The Mangrove Wetland in the Broadwater Parklands, which is within walking distance of Southport (the CBD of the Gold Coast), is a coastal management development completed in 2010 and is created by the reclamation of recycled sand (Council of the city of Gold Coast n.d.a; Elder 2009; Howe & Molhoek 2015). While four species of mangroves can be found on the Gold Coast, Avicennia marina is the dominant mangrove species in the Mangrove Wetland in the Broadwater Parklands (Council of the city of Gold Coast n.d.a; McPhee 2015). Following a brief description of how the wetlands function and what services they provide, this article in each section discusses the ecosystem benefits provided by the Mangrove Wetland in the Broadwater Parklands with the support of research and on-site observation. 

Biodiversity conservation

The wetlands play a crucial role in conserving the biodiversity of the surrounding areas through providing habitats, breeding ground and food sources. Floras such as mangroves have special adaptation to manage extreme conditions in the water and soil including the excess salt, the deficiency of oxygen and nutrition, and the soft texture of soil (Lovelock 1993; Naskar & Palit 2015). Although Lovelock (1993) argues that few faunas rely only on the wetlands as habitats, the Mangrove Wetland in the Broadwater Parklands provides a habitat for many endemic species, for example, Anus superciliosa (Pacific Black Duck),Pelecanus conspicillatus (Australian Pelican) and Cygnus atratus (Black Swan) (Burgin & McPhee 2015). Pseudomugil signifier (Pacific Blue-eye) could be found during the site visit. The wetlands also act as a breeding ground for the species through the mangroves and the water surface where many water invertebrates metamorphose, mate, lay eggs and perpetuate the species (Ezenwa & Ayinla 1994; García et al. 2015; Naskar & Palit 2015). Therefore, the turnover rate of the species in the wetlands raises due to the provision of the breeding ground.

While these species can be the prey of other predators, there are many other food sources in the Mangrove Wetland. Fruits, flowers and leaves can attract berry-eating birds and insects which take the food from the plants and help pollination and dispersal of seeds from the fruits. Woody fruits from Casuarina glauca (Swamp Oak) is an example of attraction to certain species in the Mangrove Wetland. After an attraction of new species, a climax community can be achieved in the Broadwater Parklands (Büssenschütt & Pahl-Wostl 1999; Niering 1987; Van der Valk & Arnold 2014).

Having a high biodiversity in the Mangrove Wetland benefits us in many ways. Firstly, it may reduce the external cost of a loss or an extinction of certain species. Furthermore, the biodiversity can significantly improve human health by reducing disaster risks, supporting relief and recovery effects, and lowering the chance of infectious diseases spreading (Co-operation on Health and Biodiversity 2010; World Health Organization 2017a). Therefore, it lowers the medical and healthcare cost.

Water quality control

The Mangrove Wetland performs a crucial role in water quality control. According to the Gold Coast City Council (2008), the redevelopment project consisted of a relocation and construction of new stormwater drain pipelines where the Southport CBD drains to. It can be seen on the site that the greywater and the rainwater are drained to the Mangrove Wetland. Meanwhile, mangroves in the wetlands conserve the water quality. Wetlands act like “the Earth’s filters”, which clean the water through trapping sediments and rubbish, filtering out pollutants including phosphorus and heavy metal, and absorbing nutrients, such as taking up the nitrogen in water to transform into harmless nitrogen gas (Office of Environment and Heritage 2013; World Wide Fund for Nature 2017a). By reducing the current speed, the tangled roots, pneumatophores and trunks of the mangroves can alleviate the silting problem in adjacent habitats while recycling the chemicals in the water (Lovelock 1993).

On the other hand, it is showcased by the Gold Coast Bulletin (2015) that five out of the top ten fishing spots on the Gold Coast are in the Broadwater area, for example, the Broadwater Jetty. That is important to have clean water there, not just because the heavy metals or other pollutants can kill the aquatic organisms, but also because of the bioaccumulation of toxins. As the heavy metals and other pollutants cannot be digested or broken down by the aquatic organisms, they stay and go into the human bodies when humans feed on them, directly harming their health (DeForest, Brix & Adams 2007; Pyatt et al. 2005). It is, however, argued by Dale and Connelly (2012) that an increase in mangroves in the wetlands can extend the favourable habitat of cholera, a waterborne pathogen being the cause of diarrhoea. While consuming heavy metal is fatal, the positive impacts outweigh the negatives.

In short, having clean water can lower deadly health risks by absorbing potential toxins in the water, leading to a lower death rate, while we can have a lower cost of water engineering and water treatment of the pollutants, as a result of the mangroves in the wetlands. To sum up, the Mangrove Wetland can absorb the toxins from nearby marine habitat to maintain and conserve the water quality, to lower human costs of health and water treatment.

Temperature regulation and air quality control

The wetlands are influential on regulating the temperature and improving the air quality of surrounding areas. As the soil in the wetlands is covered by water, accompanied by the presence of mangroves, a large amount of moisture can be released through evapotranspiration. Swain and Decker (2010) conclude that the temperature in the wetlands is generally lower because of the latent heat flux of evapotranspiration. As the Mangrove Wetland is within walking distance of the Southport CBD, the cooling effect of the wetlands may slightly moderate the temperature in the area through convection of air (wind). They may be able to alleviate the urban heat island effect and decrease the energy consumption leading to a lower electricity cost and a reduction of air pollution (Yuan et al. 2015; Zaman, Abdullah & Ali 2016).

While the wetlands can scale down the air pollution indirectly, it is shown that they can improve the air quality precisely. Being the sink of atmospheric carbon and other greenhouse gases, the wetlands are estimated to contain 35% of global terrestrial carbon, which assists tackling global warming (Breitfuss et al. 2015; Office of Environment and Heritage 2013). Whilst undergoing photosynthesis, mangroves can release oxygen through photolysis (as known as the light reaction) and absorb carbon dioxide through Calvin cycle (as known as the dark reaction). Therefore, the mangroves in the wetlands can regulate the air content by means of chemical reactions. Indeed, more fresh air is present in cities and it improves human health leading to a lower expense of healthcare.

To summarise, the Mangrove Wetland can cool down the surroundings by evapotranspiration in order to alleviate the urban heat island effect and lower the cost of electricity. In turn, this can, directly and indirectly, improve the air quality through photosynthesis which reduces the burden of medical expense.

Flood mitigation and coastal protection

The Mangrove Wetland takes a heroic part in mitigating flooding and protecting the coast. The United States Environmental Protection Agency (2017b) and the World Wide Fund for Nature (2017a) mention that the wetlands function like natural sponges which can trap and release the water slowly, at the same time, the roots of mangroves and other vegetation can slow the floodwater when the soil becomes completely saturated. Avicennia marina (Grey Mangrove) is the dominant species in the Mangrove Wetland in the Broadwater Parklands. Coincidentally, it is shown by He et al. (2007) that Grey Mangrove has the highest flood tolerance compared to three other mangrove species.

Flooding can harm humans and raise the cost of living. Flooding can destroy buildings and structures, for example, hospitals may be shut down and so that the medical services cannot be provided. Furthermore, the external effects of flooding lead to disturbance throughout cities, including traffic congestion, lowered household productivity and interrupted economic activities (Davies 2016). On the other hand, flooding can harm human health. While short-term flooding can bring illnesses or injuries, long-term effects of flooding can impact livelihoods and well-being, such as psychological health issues due to the stressful events after flooding such as maintenance, clean-up and insurance claiming (Ohl & Yapsell 2000).

Therefore, flood mitigation by the Mangrove Wetland not only minimises the chances of structure collapsing, but also retains economic activities, avoids potential risks on humans, and lowers the cost of living by easing the financial burden. Meanwhile, the Mangrove Wetland operates as a tool of coastal protection. While coastal erosion is mainly the result of strong wind and waves, mangroves dissipate the wave energy and the size of the waves because of the roots and stems to stabilise and protect the shorelines and coastal regions (Wells, Ravilious & Corcoran 2006). Therefore, the Mangrove Wetland can prevent people from using costly artificial structures to achieve a similar result, leading to a better visual effect in the region and a decreased cost of coastal maintenance, while maintaining the aesthetic value of the area.

Cultural preservation and recreational visitation

The Mangrove Wetland can benefit us in the way of cultural preservation and recreational visitation. Although Burgin and McPhee (2015) argue that very few residents or visitors treat the wetlands on the Gold Coast as a major attraction, the wetlands can still provide important leisure services, such as fishing (Gold Coast Bulletin 2015; World Wide Fund for Nature 2017a). During the site visit in the Mangrove Wetland in the Broadwater Parklands, human activities could be observed, for example, bird-watching, jogging and visiting. It is proved that having a visit to green space (in this case, the Mangrove Wetland) contributes to human health in the ways of natural treatment and recovery of mental illness (such as depression), relieving stress, boosting self-esteem, and physical activities (Barton & Pretty 2010; Van den Berg et al. 2010; Wolf & Flora 2015; World Health Organization 2017b). Therefore, the wetlands can be a way to lessen the Government medical expenses and the financial burden and mental issues of people through improving the health of the visitors.

On the other hand, the wetlands provide an irreplaceable function that they gather the religious, historical and archaeological value in human development around the world (World Wide Fund for Nature 2017a). The wetlands on the Gold Coast were important tradition sites for food and ceremonies of Indigenous people and therefore, they can provide a connection to Country for Aboriginal people even though the Mangrove Wetland in the Broadwater Parklands is not natural (Burgin & McPhee 2015; Office of Environment and Heritage 2013).

In short, although there does not seem to be any ecosystem functions or services related, the Mangrove Wetland, acting as a recreational visitation spot, improves human health and preserve the culture of the First People in Australia strengthening the social tie and the connection to Country.

Scientific research

Although no significant ecosystem function or service provided by the Mangrove Wetland is related to scientific research, it can act as an investigation site benefiting humans through a better understanding of the ecosystem there. Understanding the interrelationships between ecosystem services and regimes allows people to manage trade-offs and enhance the synergy of ecosystem services (Bennett, Peterson & Gordon 2009). Using regulation of water quality in the Mangrove Wetland as an example, knowledge of the functions can make the natural water engineering more effective in bringing better water quality and a lower cost of healthcare and water treatment.

Additionally, scientific research lets people understand the links between species and identify organisms (Robinson 2014). Learning the linkages such as the inter-feeding relationship (food web) can let researchers and developers know what the demand of the species is. Therefore, it is a way to conserve biodiversity whose benefits have been mentioned previously.

One step further, scientific research can be a tool of education. It does not only mean spreading the knowledge of the ecosystem but also to teach people how to understand, love and conserve the ecosystem (Lodge 2010). Dioum (1968 in The Great White Lie: William Winram at TEDxWWF 2012) had a quote while addressing the Union for Conservation of Nature at their General Assembly in 1968, “In the end we will conserve only what we love; we will love only what we understand; we will understand only what we are taught.” Indeed, education lowers the risk of artificial destruction and the cost of conservation because the people will appreciate and conserve the wetlands after learning from the ecosystem and the results of scientific research.

In short, the Mangrove Wetland in the Broadwater Parklands allows scientific research to take place which enriches the knowledge of the ecosystem there. It can benefit humans through conservation at a lower cost, and education which brings fewer man-made disruptions and damages.

Conclusion

This article has discussed the abundant natural ecosystem functions and services provided by the Mangrove Wetland in the Broadwater Parklands, and how they can benefit us economically, environmentally, socially and culturally. Ecosystem functions of the Mangrove Wetland (such as the gas exchange in mangroves) can bring ecosystem services (such as biodiversity conservation and flood mitigation) which benefit human beings (such as better health quality and lower costs). It is interesting that even though there is no symbolic ecosystem function or service related to some aspects, the Mangrove Wetland can be beneficial to us through cultural preservation, recreational visitation and scientific research. Taking benefits from this most productive ecosystem, we should start understanding the ecosystem functions and services provided by the Mangrove Wetland, so that we would love and conserve this ecosystem. Looking forward to the future and across the globe, we can start caring about the wetlands around us and then take the whole world in view, from understanding what species can be found and how the whole ecosystem functions, to stepping forward to protect and conserve the ecosystem. The next time when we are “shopping” in this “biological supermarket”, we understand, we love, and we conserve.

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