Abstract. As the second largest state in Australia, Queensland boasts some of the longest stretches of coastline and the greatest number of marine reserves in ...
HUMAN IMPACTS ON THE MARINE ENVIRONMENT OF QUEENSLAND Dr Kathy Townsend, Research Fellow and Education Coordinator, School of Biomedical Sciences, The University of Queensland
Abstract As the second largest state in Australia, Queensland boasts some of the longest stretches of coastline and the greatest number of marine reserves in the country. Within this, it contains an enormous number of marine habitats that sustains a huge biodiversity of marine species, ranging from coral to critically endangered sea turtles. However, all of these species and habitats are under threat from a wide range of human impacts. These include broad scale impacts such as climate change and marine debris, down to localised impacts such as the urban development of a local wetland. Individually, these impacts may not be huge; however, combined they are threatening Queensland’s marine species and habitats.
Introduction Types of marine environments found in Queensland Queensland is the second largest state in Australia, with over 1.7 million square kilometres of land mass. Along the northern and eastern edge of this huge state, it contains 6973 km of mainland coastlines with an additional 6374 km of island coastlines (Commonwealth of Australia 2017a). Although Queensland is only the second largest state in Australia, it does boast the largest area of marine reserves. These reserves include the North Commonwealth Marine Reserves Network, the Great Barrier Reef Marine Park, the Coral Sea Commonwealth Marine Reserve, the Great Sandy Straights Marine Park and the Moreton Bay Marine Park off the coast of Brisbane (Dept. of Environment and Energy 2017). These reserves contain a broad range of marine habitats, including seagrass, coral, mangroves, saltmarshes, rocky shore, sandy shore, estuarine, and pelagic/open ocean (Stevens and Connolly 2005). Because of all these diverse habitats, Queensland boasts some of Australia’s highest marine biodiversity, with hundreds of thousands of different species of vertebrates and invertebrates living in its waters, including many endangered and threatened species (G.B.R. Marine Park Authority 2017). Natural impacts on the marine environment The organisms living within these marine environments are regularly impacted by a wide range of natural events;
including storms, wave action, weather extremes, natural predators, and seasonal changes such as the wet and dry seasons in far north Queensland. All of these natural impacts are thought to increase biodiversity in the marine environment as the disturbances enhance diversity by creating a mosaic of habitats in which species can thrive (Sala and Knowlton 2006). However, if these disturbances become too frequent or too extreme they can reduce the amount of biodiversity a habitat can support, with only the most well adapted species being able to survive.
Human impacts on the marine environment Climate Change From the early days of hunting and gathering, through to agriculture and the industrial revolution, humans have increasingly modified and changed their surroundings. The great benefits of these technological and cultural advancements have, however, come at a cost. For example, over 100 years ago, no one would have expected that the increased release of carbon dioxide by burning fossil fuels would have had such a far-reaching impact on the world’s climate. Research has shown that on a global scale, humandriven changes in climate have lead to increases in storm damage to coastal environments, increasing floods, sea level rises, and ocean acidification (IPCC 2014). This in turn has caused a greater incidence of disease (such as black band disease and bleaching in corals), decreased ocean productivity (affecting fisheries outcomes), alteration of food web dynamics (leading to ecosystem collapse), and shifting species distributions away from their home ranges and into areas where they turn into invasive species (Hoegh-Guldberg and Bruno 2010). An example of multiple climate-driven impacts occurred in Queensland during the summers of 2016/17. A combination of above average sea surface temperatures (due to the effects of a strong El Niño and climate change), increased intensity of storm activity caused by severe tropical Cyclone Debbie and flooding caused by the increased rainfall that followed the ex-tropical cyclone, caused the second largest bleaching event
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ever recorded in Queensland’s history (G.B.R. Marine Park Authority 2017). Over half of the 344,400 square kilometre Great Barrier Reef Marine Park was affected by moderate to severe coral bleaching, while close to 10000 ha of mangrove die off happened in far north Queensland and the Northern Territories the previous summer (Duke, et al. 2017). For the first time in recorded history, bleaching was observed at the southern most reef of the Great Barrier Reef, Lady Elliot Island.
Marine pollution The term marine pollution brings to mind many different images; ranging from beaches covered in oil through to waterways filled with plastic bags.
Image 2. Oiled pelican rescued from Moreton Bay oil spill in 2009 copyright Kathy Townsend.
Pollution can consist of chemicals such as persistent organic pollutants (POPs) and trace elements (heavy metals) or more solid matter such as plastic based marine debris. Image 1. Acropora coral bleaching on LEI flats during 2017 bleaching event credit Kathy Townsend
On top of the temperature induced coral bleaching, it was estimated that close to one third of the Great Barrier Reef was within the ‘catastrophic damage zone’ of the cyclone’s path when Tropical Cyclone Debbie crossed the coast at Airlie Beach on 28 March 2017. This caused physical damage to the already weakened coral and mangrove environments. Soon after the cyclone reduced in intensity, the system was followed by torrential rain into large parts of the central and southern Great Barrier Reef catchment. This excess rainfall caused flooding and erosion of the Burdekin and Fitzroy Rivers. The floodwaters flowing into the GBR basin, bring sediment, pollution and marine debris, affecting coral, mangrove and sea grass environments. All of this was on top of ongoing outbreaks of coral disease and crown-of-thorns starfish outbreaks. As mentioned previously, disturbances are part of the natural process in maintaining diversity in the natural environment. However, what is being seen now is that the disturbances are becoming more widespread and are occurring more frequently, reducing the resilience of Queensland’s natural habitats (G.B.R. Marine Park Authority 2017).
Prior to European settlement, pollution was primarily organic based, items such as food scraps, human/ animal waste, organic fertilizers, and storm water. These broke down to nitrates and phosphates and were taken up as nutrients by (the then abundant) marine plants, such as fringing mangrove forests and seagrass beds. However, the pollutants being introduced to the marine environment have changed as Queensland matured as a state. Chemicals, plastics and a wide range of pollution are now being introduced to the environment. Chemical and physical pollution have one thing in common – they are all highly resistant to decay. As such, these compounds have been shown to bioaccumulate in aquatic organisms and many can biomagnify up the food chain, further exacerbating their long-term environmental impact. Pollutants enter the marine environment in multiple ways; through weathering and erosion of rocks, mining activities, urban development, agriculture, run-off, and industrial processes. Many chemical pollutants can bind to particles and organic matter in the water column and ultimately accumulate in the sediment (Haynes and Johnson 2000). When disturbed, or if water quality is altered (for example due to flooding), sediment-bound pollutants can be released and become available to living organisms (Brady, et al. 2014). Animals are then exposed to the pollutants through the consumption
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of contaminated food sources such as seagrass, macroalgae, benthic crustaceans, soft sponges/corals and jellyfish, as well as through incidental ingestion of contaminated sediments during benthic feeding (Aggett, et al. 2015).
In Moreton Bay, 30% of sea turtles and 90% of sea birds have been found with marine debris within their gastrointestinal system (Schuyler, et al. 2012, Acampora, et al. 2013).
Image 3. Researcher takes samples from sting rays that were stranding due to a chemical spill photo by Kathy Townsend.
Marine debris is defined as any man-made product entering the marine environment. Studies have shown that plastic polymers make up 60-80% of marine debris (Derraik 2002). Plastic takes a very long time to break down in the environment and can cause a wide range of health issues for both wildlife and humans (Ogata, et al. 2009). The majority of the marine debris originates from land based sources (80%), while the remaining 20% are discarded or lost at sea from vessels (Faris and Hart 1994). Marine debris negatively affects marine creatures in one of two ways, either through ingestion or entanglement. In both instances, the interaction with the debris can result in death. The most common cause of entanglement occurs in lost or discarded fishing gear such as crab pots, nets, and fishing line,
Image 4. Green sea turtle found entangled in fishing line by Kathy Townsend
while ingested hooks, plastics and balloons are lethal to both sea turtles and seabirds (McPhee, et al. 2002).
Image 5. Plastic and balloons removed from the intestines of a green sea turtle by Kathy Townsend.
Invasive species and disease Invasive species are non-native marine plants or animals that have been introduced to Australia via human activities, such as shipping, domestic aquariums, or aquaculture. Australia currently has over 250 introduced marine species, many of which can potentially negatively impact our marine industries and our environment (Commonwealth of Australia 2017b). Invasive marine species that have impacted Queensland waters include the Asian Green Mussel and the Asian Bag Mussel (Business Queensland, 2017 a,b). In both instances, they arrived in Australia by clinging to the hulls of ships and transported in ship ballast water. They are weedy species, meaning that they can tolerate a wide range of conditions and grow quickly, particularly in areas where they have few predators. These species have outcompeted and smothered native species; fouled jetties and other man made structures; and threaten commercial aquaculture industries. Marine animals entering Australian waters can also bring disease. Recently, an entire industry collapsed due to the importation of sick prawns into South East Queensland. These prawns contained a disease known as white spot, which is caused by a virus from the genus Whispovirus (Dept. of Agriculture and Fisheries 2017). It is highly contagious and is very difficult to control. Until recently, Australia was the only country in the world that had remained white spot free. In Asia and America, white spot has caused severe losses in the aquaculture prawn 5
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industry. In Moreton Bay, off the coast of Brisbane, white spot was not only found in prawn farms but escaped into the surrounding environment, affecting wild caught prawns as well. The consequence of the disease meant that hundreds of thousands of aquaculture prawns had to be killed and their ponds flooded with chlorine to kill the virus. For the trawler fishermen that work in Moreton Bay, the consequence is that they have not been able to export their product outside of the local region. In both instances, hundreds of thousands of dollars have been lost by the industry due to this imported disease.
Bay and Harvey Bay. In both instances, the number of strandings of both sea turtles and dugongs in these regions, due to malnutrition, more than doubled (Meager and Limpus 2012 a,b).
Image 7. Female dugong stranding after Brisbane floods credit Kathy Townsend.
Overfishing and bycatch impacts On top of all the impacts occurring to marine habitats, species are also being directly removed from the environment. Researchers have predicted that if current fishing rates continue, the world’s fisheries will collapse by 2050 (Worm et al. 2006). Image 6. Prawn trawlers moored at the marina unable to fish for prawns due to white spot by Kathy Townsend.
Urban and rural development Human impacts on the environment are those in which habitats are severely altered, making it difficult for the native plant and animals species to survive. These impacts may be direct, such as those caused by coastal development that can result in the removal of entire ecosystems to build infrastructure or due to overexploitation, such as over harvesting oyster reefs or mangrove logging. Other impacts can be more indirect, caused by agricultural land practices upstream, which release sediment and fertilizers into surrounding waterways and ultimately flow out into the marine environment. Both urban and rural development can cause increased sedimentation and eutrophication. Water running from the land picks up sediment and nutrients, decreasing water quality and increasing turbidity of the water column. Corals and seagrass beds are negatively affected by this poor water quality, causing diebacks that can then affect animals further up the food chain. During the 2010/2011 floods in South East Queensland, the muddy water prevented sunlight penetrating through the water column to the seagrass underneath. This caused a mass die off of seagrass in both Moreton
Image 8. Fewer large schools of fish such as these trevally are expected to be seen by 2050 by Kathy Townsend.
However, the authors found that if the number of marine protected areas increased globally, then this would positively impact on biodiversity. This in turn would increase productivity and make ecosystems less susceptible to environmental and human-caused impacts. The study found that if given a helping hand, ocean ecosystems have a strong ability to repair themselves.
Summary Human impacts have far reaching consequences for Queensland’s marine environment. A combination 6
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overfishing, global warming, biological introductions, and pollution, has caused a rapid decline in Queensland’s marine biodiversity. The consequences of this biodiversity loss include changes in ecosystem function and a reduction in the provision of ecosystem services, such as the protection from storm surge and erosion in coastal areas. Unless drastic changes are made in how we interact with the marine environment, it is predicted that global biodiversity loss will not only continue but it is likely to accelerate in the future, with up to 90% of the world’s fish population and up to 80% of coral reef habitats expected to be destroyed in the next few decades.
Student Activities: 1. Outline the natural and human causes of change to the marine environment. 2. Discuss how the size and frequency of natural disturbances to the marine environment can affect the resilience of marine ecosystems. 3. Construct a mind-map to summarise the impacts of climate change on marine environments. 4. Research and explain the processes: a. bioaccumulation b. biomagnification c. eutrophication d. coral bleaching 5. Discuss the causes and economic consequences of invasive marine species. 6. Explain how urban and rural development threaten marine ecosystems. 7. Use the internet to research solutions to the issue of plastic pollution in marine environments. 8. Evaluate the effectiveness of a named marine protected area in conserving the environment. 9. Draw a Futures Wheel to consider the economic and environmental consequences of overfishing. 10. Aquaculture is a sustainable solution to the issue of overfishing. Discuss.
References and further reading Acampora, H., et al. 2013, “Comparing plastic ingestion in juvenile and adult stranded short-tailed Shearwaters (Puffinus tenuirostris) in eastern Australia.” Marine Pollution Bulletin 78: 63-68. Aggett, P., et al. 2015, Essential Metals: Assessing Risks from Deficiency and Toxicity. Handbook on the Toxicology of Metals (Fourth Edition), Academic Press, San Diego. Brady, J. P., et al. 2014, “Temporal trends and bioavailability assessment of heavy metals in the sediments of Deception Bay, Queensland, Australia.” Marine Pollution Bulletin 89(1-2): 464-472. Business Queensland. 2017a, “Asian bag mussel.” Prohibited invasive animals, Retrieved 13 Aug, 2017, . Business Queensland. 2017b, “Asian green mussel.” Prohibited invasive animals, Retrieved 13 Aug, 2017, https://www.business.qld.gov.au/industries/farms-fishingforestry/agriculture/land-management/health-pestsweeds-diseases/pests/invasive-animals/prohibited/asiangreen-mussel. Commonwealth of Australia. 2017a, “Border Lengths States and Territories.” Retrieved 13 Aug, http://www. ga.gov.au/scientific-topics/national-location-information/ dimensions/border-lengths. Commonwealth of Australia. 2017b, “Marine Pests.” The National System for the Prevention and Management of Marine Pest Incursions. Retrieved 13 Aug, 2017, http:// www.marinepests.gov.au/marine_pests/Pages/default. aspx. Department of Agriculture and Fisheries. 2017, “White spot disease.” Health and diseases, Retrieved 13 Aug, 2017, https://www.daf.qld.gov.au/animal-industries/ animal-health-and-diseases/a-z-list/white-spot-disease Department of Environment and Energy. 2017, “Australian marine parks (Commonwealth marine reserves).” Retrieved 13 Aug, 2017, http://www. environment.gov.au/topics/marine/marine-reserves. Department of Environment and Heritage Protection (2012). “Endangered animals.” Retrieved 13 Aug, 2017, https://www.ehp.qld.gov.au/wildlife/threatened-species/ endangered/endangered-animals/ Derraik, J. G. B. 2002, “The pollution of the marine environment by plastic debris: a review.” Marine Pollution Bulletin 44(9): 842-852. Duke, N. C., et al. 2017, “Large-scale dieback of mangroves in Australia’s Gulf of Carpentaria: a severe ecosystem response, coincidental with an unusually extreme weather event.” Marine and Freshwater 7
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Research. Online Faris, J. and Hart, K. M. 1994, Seas of Debris: A Summary of the Third International Conference on Marine Debris. Third International Conference on Marine Debris, North Carolina Sea Grant College Program, Raleigh, North Carolina. Great Barrier Reef Marine Park Authority. 2017, “Reef health.” About the Reef. Retrieved 13 Aug, 2017, http:// www.gbrmpa.gov.au/about-the-reef/reef-health. Haynes, D. and Johnson, J. E. 2000, “Organochlorine, heavy metal and polyaromatic hydrocarbon pollutant concentrations in the Great Barrier Reef (Australia) environment: a review.” Marine Pollution Bulletin 41(712): 267-278. Hoegh-Guldberg, O. and Bruno, J. F. 2010, “The impact of climate change on the world’s marine ecosystems.” Science 328(5985): 1523-1528. IPCC. 2014, “Climate Change 2014 Impacts, Adaptation, and Vulnerablity. Part B: Regional Aspects.” Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. McPhee, D. P., et al. 2002, “Swallowing the bait: is recreational fishing in Australia ecologically sustainable?” Pacific Conservation Biology 8: 40-51. Meager, J. J. and Limpus, C. J. 2012a, “Marine wildlife stranding and mortality database annual report 2011. I Dugong.” Conservation Technical and Data Report 2011, 1: 1-30. Meager, J. J. and Limpus, C. J. 2012b, “Marine wildlife stranding and mortality database annual report 2011. III. Marine Turtle. .” Conservation Technical and Data Report 2012, 3: 1-46. Ogata, Y., et al. 2009, “International Pellet Watch: Global monitoring of persistent organic pollutants (POPs) in coastal Waters. 1. Initial phase data on PCBs, DDTs, and HCHs.” Marine Pollution Bulletin 58(10): 1437-1446. Sala, E. and Knowlton, N. 2006, “Global marine biodiversity trends.” Annual Review of Environment and Resources 31: 93-122. Schuyler, Q., et al. 2012, “To Eat or Not to Eat? Debris Selectivity by Marine Turtles.” PLoS ONE 7(7). Stevens, T. F. and Connolly, R. M. 2005, “Local-scale mapping of benthic habitats to assess representation in a marine protected area.” Marine and Freshwater Research 56: 111-123. Worm, B., et al. 2006, “Impacts of Biodiversity Loss on Ocean Ecosystem Services.” Science 314(5800): 787790.
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