Coral Catastrophe?

Being an ecology enthusiast with a particular fondness for corals, todays post is one of my favourites so far. We all acknowledge that coral reef ecosystems are extremely important to the health of the oceans. While they cover only 1% of the oceans, it is estimated that one quarter of all marine biodiversity spends, at least part of their life on a coral reef. When corals are mentioned most people think of tropical waters and an instant picture of the Great Barrier Reef pops into mind. To me the term 'coral' automatically conjures up brightly coloured images present in the Pixar film, Finding Nemo.

However, as the NOAA state shallow water corals are only one type. There are cold water corals and deep sea corals that have limited light producing soft corals. 

What are corals?

The Oxford English Dictionary defines corals as ' hard stony substance secreted by certain marine coelenterates as an external skeleton, typically forming large reefs in warm seas'. 

Corals are invertebrate animals belonging to a group called the Cnidaria. They can exhibit a wide range of colours, shapes and come in all sizes. Each coral is made up of hermatypic polyps and most live in colonies. A coral colony can grow to be very large indeed. The hermatypic polyps produce calcium carbonate to form calyx (NOAA, 2011). The calcium carbonate adds to the coral skeleton forming the beginnings of the coral structure. Corals develop slowly over millions of years, today the corals you see have been growing for around 50 million years. To date there are around 800 known species of hard coral and more being discovered, just as new species of marine animals are being found in the most remote ocean locations every day. 

Source. Coral forming diagram.

Where are corals found?

Coral reefs are found throughout the oceans, from deep, cold waters to the shallow tropical waters of the Indian Ocean. Tropical reefs extend from 30 degrees North and South of the equator. However, cold corals can also be found in places closer to home such as off the West coast of Scotland and Ireland. Cold water reefs have also been found in the Mediterranean. 

There are various factors that cause the pattern of coral reefs throughout the world. 

These include:

The role of ocean temperature

The effects of emersion

Bathymetry

Levels of sedimentation



Types of Coral Reef

• Fringing Reef: most common type of coral reef located close to land. 

• Barrier Reef: looks like a fringing reef, however, it is located further away from the shore. They are separated from the shore by a band of water.

• Atoll: large ring shaped reef, which create a lagoon in the middle. 

Anthropogenic threats to coral reefs
Corals are ecosystems that have been developing for years, and in this time have been subjected to natural change. The worry now is that with increasing human stresses, corals may not be able to cope.   WWF (2010) states that already 'one quarter of coral reefs are subjected to damage beyond repair, with another two thirds under threat'. With reef building corals representing a critical component for marine biodiversity, it becomes important to conserve these ecosystems in order to conserve the species that use coral environments (Huang and Roy, 2013). 



Destructive fishing practices: Blast, dynamic fishing and bottom trawling are types of fishing practices that cause devastation to sensitive coral reefs. Bottom trawling has been widespreadsince the 1980s. The large rubber tires on the nets can damage the coral structures. Dynamic fishing is  where explosives are set off underwater destroying coral. This has been particularly a problem in South East Asia (Cadwell and Fox, 2006). 



Pollution: Urban and industrial waste being released into the oceans which are poisoning the reefs.  Pollutants increase the amount of nitrogen in the waters causing an overgrowth of algae, which can smother the reefs, concealing them from sunlight which the polyps need to survive (McManus, 2000).



Sedimentation: Anthropogenic coastal construction, mining, logging and tourism developments can cause erosion. This erosion causes increased levels of sediment being produced. Sediment covers coral, almost suffocating it and causing the corals to produce a protective mucus (MES, 2002). This process takes incredible amounts of energy and if corals are overworked they can die. 



Ocean acidification: As mentioned in my previous post, marine environments are particularly threatened by climate change and the increasing pH of ocean waters. Since the beginning of the industrial revolution, the oceans have been absorbing increasing amounts of excess carbon dioxide. With ocean acidification, corals cannot absorb the calcium carbonate needed to maintain their structures and therefore the reef will dissolve (SCOR, 2009). 



        
Ocean acidification effects on coral reefs. 


Global warming and coral bleaching: In the Anthropocene, global warming is a known threat to many ecosystems. It occurs because carbon dioxide and other greenhouse gases cause a blanket, preventing heat from the sun to escape, warming the atmosphere. Ocean warming is extremely devastating to coral biodiversity, which is sensitive to changes in temperature. If oceans stay warm for several weeks, zooplankton leave the corals, turning them white in the process, because it is the zooplankton that gives corals their unique colours. NOAA (2013) discussed how in 2005, the USA lost half of its coral reefs in the Caribbean in only one year due to a huge coral bleaching disaster. 



       
Coral Bleaching: showing the distinctive white coral. 



However, a recent study showed it is not all bad news. Elevated nitrogen and phosphorous at a study site in Florida Keys from 2009-2012, showed coral bleaching. What this study also noted was that once the injection of pollutants ceased, the corals became able to recover and in a surprisingly short period of time (PhysOrg, 2013). 


There are other threats to corals, however I have rambled on too much already. I hope you enjoy this post and it provides a insight into the marine biome and the anthropogenic impacts of coral ecosystems. Being a corals fanatic, I find it extremely worrying that humans can be having such disastrous effects to one of the world's most beautiful environments. I, for one, want to be able to dive  and explore these unique ecosystems, enjoy their bright colours and extraordinary patterns and it would be devastating if these environments were not there for people to enjoy. 

Score board update: Anthropocene 3 - 1 Biodiversity 

Oceans- What will the future hold?

In previous posts I have concentrated on mainly terrestrial biodiversity (however not on purpose). Today I take a swim with the fishes to investigate one of Earth's most interesting biomes- the ocean.

'The ocean covers nearly three quarters of the Earth's surface, provides about half of the oxygen we breathe and feeds billions of people every year' (Le Roux, 2013). 

The oceans have been protecting the Earth from the worst effects of human induced climate change for years by absorbing excess carbon dioxide (Bijma et al. 2013). This absorption, however, is having a negative effect driving the oceans into an acidic state. Along side this acidification, ocean warming is having grave impacts on the structure of many marine ecosystems. Bijma et al.(2013) coined ocean warming, acidification and deoxygenation the 'deadly trio' of anthropogenic impacts that are causing  accelerated loss of marine populations (Worm et al. 2006). Since the industrial revolution the world's oceans have become 26% more acidic and will continue to force oceans into a acidified state at an unprecedented rate.

Ocean acidification is the reduction in the pH of the ocean waters by the uptake of carbon dioxide from the Earth's atmosphere. It can also be caused by chemical pollution into the oceans. The carbon dioxide dissolves in the seawater generating changes in seawater chemistry. The addition of carbon dioxide increases the concentration of bicarbonate ions and carbonate ions which, consequently lowers the pH making oceans more acidic. For a beginners insight into ocean acidification take a look at the below flow chart, showing the changes in chemistry from slight alkaline to acidified seawater. 

Beginners guide to ocean acidification.

Many recent reports, have discussed how ocean change may be faster than any time in the last 300 million years, predicting that by 2100 there will have been a 170% increase in ocean acidity. But is it all doom and gloom for oceans? There has in fact,  been scientists that have discussed how marine species could survive and even thrive (seagrass) under ocean acidification and warming (McGrath, 2013). 

What environmental scientists are most worried about is the effect of the 'deadly trio' on corals. In the Great Barrier Reef half of the coral cover has been lost over the past 27 years. There have also been dramatic coral bleaching events in 1998 and 2002 due to anthropogenic ocean warming. In the Southern Ocean, we can unfortunately already see corrosion of pteropods (sea snails) shells. In my next post, I aim to expand on corals in more detail, focusing on the threats posed by the anthropocene to these highly sensitive environments. 

Coral Disaster: Great Barrier Reef coral bleaching. Source. 

With a carbon release of around 30 gigatonnes of carbon dioxide a year, it is no surprise that academics are worried about a major ocean extinction. As I touched upon in my previous post a sixth mass extinction' is a upcoming worry. However, speculative this theory may be, oceans are one of the biomes which are most vulnerable to a huge biodiversity decline. With changing ocean conditions, many species could possibly find themselves in unsuitable environments, especially in oxygen poor "dead zones"(Le Roux, 2013). 

What will the future hold for the oceans? Will there be a biodiversity loss in one of the worlds most diverse environments? Keep your eyes peeled for my next post which will look at the threats posed to corals.

Score Board Update. 

Anthropocene 2- 1 Biodiversity.

City Biodiversity and the development of 'Green Urbanism'

As previously suggested we have entered a new geological epoch called the ‘Anthropocene’ where the cumulative impacts of billions of people are being experienced. The impacts are so extreme that we are now disrupting this steady state life system through climate change, toxic air pollution, biodiversity collapse and social inequality (Partington, 2013) Recently, there has been a lot of  discussion in scientific literature surrounding biodiversity and urbanization, especially relating to city biodiversity. Urbanisation is the physical growth of urban areas as a result of global change. With a booming human population, city biodiversity is set to become a major factor in our increasingly interconnected world. The Convention on Biological Diversity (2011) stated that by 2050, almost 3 billion additional people will inhabit the world’s cities and the world will have undergone the largest and fastest period of urban expansion in all of human history. A recent estimate reveals that the area directly impacted by new urban infrastructure within the next 40 years will roughly cover an area the size of Mongolia, with obvious impacts on the natural habitat. Consequently, urban growth will impact the provision of many ecosystem services and the demands of cities will reshape most rural landscapes in the coming decades.

Map showing the transport links of humanity and the interconnectivity of the globe.

One way urbanisation can cause disturbance to biodiversity is through habitat loss (Czech et al. 2000). It is often cited as the primary cause of species endangerment in the United States. As can be seen in the table below, urbanisation caused 275 endangered species in United States and Puerto Rico (Czech et al. 2000). The only human impact that tops urban development is non-native species disturbance. Czech (2004) states that urbanisation is one type of habitat loss and that this anthropogenic implication can transform the “economy of nature” to the human economy. In some cases of habitat loss, natural capital is simply cleared away to make room for human economic infrastructure and enterprises. 

It is not just cities that will have an increasing human population, infact most of the urban expansion is predicted to occur in medium to small urban areas of low economic capacity. Since urbanisation is changing the nature of our planet, preserving biodiversity on this urban world requires going well beyond the traditional conservation approaches of protecting and restoring what we think of as “natural ecosystems,” and trying to infuse such elements in the design of urban spaces (Convention on Biological Diversity Report, 2011). The report also states that 

‘cities already represent a new class of ecosystems shaped by the dynamic interactions between ecological and social systems. As we project the spread of these ecosystems across the globe, we must become more proactive in trying not only to preserve components of earlier ecosystems that they displace, but in imagining and building entirely new kinds of ecosystems that allow for a reconciliation between human development and biodiversity’.

It is refreshing to hear that people are accepting urbanisation and its affect on biodiversity, including trying to think creatively about new spaces in the city to encourage species diversity. While we know that urbanisation, through habitat loss, can displace many species it becomes vital to understand that some species have infact evolved adaptive responses to thrive under urban pressures. Some endangered species find suitable habitats in urban ecosystems, especially with innovations such as rooftop gardens and vertical forests being established. Anthropogenic technological advancements such as supplementary watering systems, have the potential to offer novel habitats and niches for species quite different from those in more natural ecosystems (McKinney, 2002). 

However, just because urbanisation poses a threat to biodiversity, it does not mean that cities cannot sustain diverse ecology. In fact many cities have high species richness and several are located within 'biodiversity hotspots'. Such cities include, Berlin, Brussels, Chicago, Frankfurt, Helsinki, Mexico City, Sao Paulo, Singapore and Vienna. The assessment of Cities and Biodiversity Outlook (CBO) argues that cities should facilitate for a rich biodiversity and look after the multitude of ecosystem services, such a rich biodiversity can provide, rather than being the culprit of enormous ecological footprints. With such a diverse ecology, cities have the potential to mitigate the effects of climate change. The Japanese district of Yokohama, which emitted almost 20 million tonnes of carbon dioxide in 2007, has now recognised the importance of biodiversity in stabilising the local climate. Innovations such as green roof tops and walls have been developed to act as carbon sinks (SRC, n/d). It is now being acknowledged that it is the responsibility of architects to develop 'green' cities, including creating an integrated holistic approach to create sustainable urban infrastructure. 

To create sustainable cities, developments such as green corridors along highways, railways or bikeways have been planned. There are many new and exciting ways in which architecture and biodiversity are becoming linked. Edwards (2010) explains how the political focus on global warming has tended to reduce the importance of architects in protecting biodiversity. However, the impacts that architecture has upon ecosystems, including decisions regarding building materials, sourcing the materials, rehabilitation of existing structures, decisions regarding walls, roofs and landscape, are enormous. Architects can see this as an opportunity to connect architecture to nature. An example of this is by Edwin Lutyens, who created bat and owl boxes within roofs, making them part of a more ecological architecture (Edwards, 2010). Although architecture does not traditionally concern itself with such matters, the growth of sustainability focused global narratives and EU regulation exposes building design and construction to the close scrutiny of the biodiversity movement. Some architects have already started to fill in the gap. The 'cradle to cradle' idea owes much to an understanding of ecological systems, taking principles from nature and applying them to buildings. It is a holistic framework that aims to create systems that are efficient and also essentially waste free. Similarly the 'biomimicry' design movement and such innovations as bioclimatic skyscrapers and green urbanism promoted over a decade ago, have a clear commitment to addressing biodiversity (UICN, 2013). Ken Yeang, a Malaysian architect and ecologist inverted the high-rise to be designed as a 'city-in-the-sky'. The first example of this was the National Library Singapore (2005). The building features large 40m high 'public realms-in-the sky' in the form of two landscaped sky court gardens.  

Urban design provides the framework for the effective use of land, allowing greenery and biodiversity to penetrate the city. With good design, urban areas can provide opportunities, not merely threats, to ecological diversity. These corridors of biodiversity, including urban wetlands, allotment gardens, botanic gardens, parks and roadside trees can be linked into a network, creating a 'green' city. Architects also have a key role to play to reduce energy consumption. The choice between steel, concrete, masonry or timber construction is complex from an energy point of view (UICN, 2013). However, society is trying to gain a better understanding of green construction. 

Two examples, where the connections between urbanisation and biodiversity are being acknowledged are London Heathrow and Mayesbrook Park. London Heathrow has recently completed a new survey of the biodiversity in its 30 hectare site. They found that the airport offered a range of habitats including grassland, and other landscaped habitats. Within these habitats Heathrow was home to a multitude of rare species of bats, spiders and insects. In total it discovered 129 species of spider and 304 species of beetles (Travel News UK, 2013). This goes to prove that not all urbanized areas threaten species biodiversity, in fact, if the design is incorporated with green infrastructure in mind, species can actually flourish in man made habitats. London's Mayesbrook Park, in urban East London, has transformed a rundown 45 hectare park into a showcase of public green space. The project involved creating a new floodplain that can naturally store floodwater, planting new shrubs and trees to enhance habitats for species encouraging increased biodiversity. This £3.8 million project clearly demonstrates how restoration of biodiversity in cities, can also provide other knock on effects such as climate change adaptation and enhance the well being of people living in the city (Convention of Biological Diversity, 2011). 

Mayesbrook Park,  East London

Overall, cities can provide a unique habitat, one that can produce a rich biodiversity. With an increasing urban population, 'green' urbanism is key to producing sustainable cities in the future. It is vital that governments and planning agencies take into account the benefits that new urban spaces can provide to not only biodiversity but also to localised climate change and air pollution. With urban habitats being surprisingly diverse, such richness of habitats also results in the generation of multiple ecosystem services, which can contribute significantly to human well being. With growing awareness of the value of biodiversity and ecosystem services cities with rich native biodiversity should ensure that their biodiversity is conserved. I will leave you with the words of Professor Thomas Elmqvist, scientific editor of the assessment at SRC, 'cities need to learn how to better protect and enhance biodiversity because there is a direct relationship between biodiversity and many ecosystem services'. 

Score Board Update: Anthropocene 1- 1 Biodiversity 

Biodiversity and urbanisation- Introduction

Hi all,  hope everyone is having a good start to their reading week. I am currently in the process of writing my next blog post which will focus on biodiversity and urbanisation. Personally, I find this topic extremely interesting (hence why it seems to be taking so much time to collaborate my many pages of reading notes. I think I went slightly overboard on the whole reading around the topic!). Are you excited yet? Well if the thought of biodiversity makes you yawn with boredom... here is a short video to get you anticipating tomorrows big reveal.

The key questions that I aim to explore in tomorrows post are:

1) What is urbanisation?
2) Do cities have rich or poor biodiversity?
3) How is urbanisation harmful to biodiversity?
4) Is it possible for buildings to restore nature?
5) Can increased urbanisation lead to increased invasive species?
6) Are new schemes being adopted to conserve biodiversity in the age of unregulated urban sprawl?

Enjoy and keep an eye out tomorrow!