License to Krill II

Last week, I looked at the impact of a whaling ban on krill population and penguin populations. This post will discuss natural causes of changes in krill population that humans have no (direct or indirect) impact on. Like last week I will continue my focus on the West Antarctic Peninsula (WAP).

Figure 1 shows the change in winter sea ice extent from 1980 and 2010 and it is evident that there has been a reduction in winter sea ice extent during the period.

Figure 1. Winter sea ice extent in 1980 and 2010. Adapted from: Lenfest Ocean Program, (2011)

What is causing reduced sea ice extent?

Trivelpiece et al. (2011) and Vaughan et al. (2003) argue that this region has experienced a 5-6^oC increase in mean winter air temperatures in the past 50 years and this is resulting in decreased winter sea ice extent. Figure 2 shows a gradual increase in mean winter temperatures from 1950 to 2000. The grey region is of particular interest because it shows a warming trend from 1980 to 2001.

Figure 2. Mean winter temperatures at the Faraday Station. Adapted from: Lenfest Ocean Program, (2011)

By comparing figure 2 with figure 1, it is possible to correlate an increase in mean temperatures with reduced sea ice extent. However there are also other factors affecting sea ice extent.

Atmospheric and oceanic temperatures are changing in the WAP region due to changes in the El Niño Southern Oscillation (ENSO). This is reducing sea ice extent. El Niño is a weather event that occurs in the Pacific when there are weaker trade winds and this alters the climate in the surrounding regions, notably South America and Australia. During El Niño, warm water that would normally be in the West Pacific flows to the East Pacific and atmospheric pressure falls. South America experiences unusually wetter climate while regions near Australia experience more drought-like conditions. La Niña, on the other hand, is the opposite effect where atmospheric pressure increases, trade winds blow more intensely and cold water flows to the west Pacific.

Shevenell et al. (2011) explain that during La Niña events, there are higher sea surface temperatures in the WAP and this reduces sea ice extent. The reason for this is that there is high pressure in the Bellingshausen Sea (see figure 3) which brings warm air towards Antarctica, causing reduced sea ice extent. Furthermore, north easterly winds dominate which Harangozo (2006) and Quetin et al. (2007) find is negatively correlated with sea ice extent (strong north easterly winds lead to reduced sea ice extent) because it does not provide good conditions for ice formation. Furthermore, Shevenell et al. (2011) mention that there are positive feedbacks that enhance this effect, which can explain how winter sea ice extent falls even when there is no La Niña event. 

Figure 3: Bellingshausen Sea in West Antarctica. Adapted from The Encyclopedia of Earth

Sea Ice Extent and Krill Population

You must be wondering how sea ice extent is related to krill population. One way sea ice helps the krill population is through providing a habitat for microbial communities that young krill use as a source of food (Quetin et al. 2007). This improves their chance of survival and helps increase the krill population in the summer (ibid). Additionally, high sea ice extent and duration is positively correlated with reproductive success of krill (Loeb et al. 1997). The fact that winter sea ice extent is reducing means that there will be a smaller krill population surviving to the summer without the microbial communities to feed on. Hence, krill population will decline in the long term if La Niña events are frequent. Even under normal conditions when there is no La Niña event, there could be lagged responses in the system as it gets used to the normal climatic conditions. This can result in long term variability in krill populations. 

Hopefully in this post I have shown that krill populations are not solely affected by human actions. Natural climate variability is often under-stated in the media and in literature about wildlife. Today, I have highlighted how complex it is to try and understand how humans and natural variability affect Antarctica. 

This post has helped level the playing field, so the updated scores are now negative impacts 4, positive/ natural impacts, 3. Next week, I will move on to the effects of plastics on Antarctic seals. There are no surprises as to which way the scores will lean next week...

How Krill Variability Affects Penguins

This post will focus on how krill variability in the West Antarctic Peninsula (WAP) and Scotia Sea affects populations of Adélie and chinstrap penguins via the food chain.

Whaling

As mentioned in my previous post, krill fishing has become one of the main drivers reducing krill population and increasing competition for krill. But this is not the only impact that humans have had on krill population. Indirectly, through the introduction of whaling and sealing restrictions, competition for krill is increasing, causing stress among krill population. In turn, this is causing a decline in the populations of Adélie and chinstrap penguins.

For example, the International Whaling Commission banned the whaling of blue whales in 1966 (National Oceanic and Atmospheric Administration Fisheries, 2014) which is increasing the population of baleen whales (blue whales are a type of baleen whale) and therefore increasing demand for krill. This reduces available krill to penguins, particularly because blue whales’ diets consist mostly of krill (ibid). More competition for krill means that krill populations may decline even further than they have. Trivelpiece et al. (2011)'s research project in the South Shetland Islands in the West Antarctic Peninsula (see figure 1) discovered that Adélie and chinstrap penguin populations have declined more than 50% in the last 30 years, which is approximately during the same time that whaling bans were introduced in the Antarctic. 

Figure 1. Map showing the South Shetland Islands and the West Antarctic Peninsula. Source: Lenfest Ocean Program, (2011)

This suggests that humans have indirectly affected penguin populations via the food chain and the impact on krill population. Whaling bans therefore have a positive impact on whale populations, but a potentially negative impact on penguin populations. The fact that this happens demonstrates the interconnectedness of Antarctic wildlife and the importance of krill in the food chain. It also highlights the complexity of food chains. Food chain processes are natural and once humans alter these mechanisms, many species, not just one, are affected. Even if humans have good intentions (e.g. to protect whales), there can be negative indirect effects as well. 

Trivelpiece et al. (2011) further mention that the effect of a reduction in krill availability for penguins is predicted to increase as krill fishing increases. Humans, therefore, have a variety of impacts on whale, penguin and krill populations and these impacts are all holistic. The impact that humans have had on Antarctica is both positive (on whales) and negative (for penguins and krill). Because of this, I will classify the total impact as neutral, so for the first time in my blog, the impacts cancel out and the scores remain unchanged! Just to remind you, they stand at negative impacts 4, positive/ natural impacts, 2.

Next week I will explore an argument against anthropogenic causes, focussing on how natural climate variability can cause changes in krill population. Thanks for reading!

License to Krill I

Krill are small crustaceans that resemble shrimp and feed of diatoms. They are very abundant in Antarctica, in fact their total global combined weight ranges from 500 to 700 million tonnes (Voytek,1990)! Krill are small creatures as demonstrated by figure 1, which shows their size relative to a paper clip. Despite how small they are, they are essential for life in Antarctica. According to the National Geographic (2014), 'without krill, most of the life forms in the Antarctic would disappear'.

Figure 1. Size of krill relative to a paperclip. Source: The National Geographic (2014)

Why are krill so important?

Krill play an important role in the Antarctic food chain. Krill are at the bottom of the food chain which means that they are important food sources for whales, penguins, seals, fish, copepods and sea birds (Tomaselli, 2012). These animals make up the majority of those found in Antarctica. Because so many animals rely on krill, a change in krill availability may result in starvations among some of these Antarctic animals.

Figure 2 shows which animals feed on krill. Krill are consumed by Emperor penguins, Adélie penguins, crabeater seals, leopard seals, and baleen whales. It’s important to note that the figure does not show all of the animals feeding on krill, only a selection.

Figure 2: Antarctic food chain. Source: Voytek (1990)

Krill population

Given the importance of Antarctic krill in maintaining populations of marine and terrestrial animals, it is desirable to keep krill populations steady. But this not the case. In fact, humans are reducing the levels of krill in Antarctica, both directly and indirectly.

First I’ll explain the direct impacts on krill population. Krill populations are declining due to fishing. The Soviet Union began fishing Antarctic krill in the early 1960s (Aronson et al. 2011). In the 1970s and 1980s, many other countries followed (ibid). Krill are sought after because they are used as fish bait, fish feed in aquaculture and for aquarium trade (ibid). Furthermore, krill can be transformed into krill oil, which is a source of omega-3 and can have beneficial health impacts for us. Krill oil can help protect us against and lower the risk of suffering from health conditions such as rheumatoid arthritis, heart disease, stroke, depression and osteoporosis (University of Maryland Medical Center, 2013; accessed 28 November 2014).

These health benefits incentivise pharmaceutical companies to fish Antarctic krill because there is a market for krill oil products. Below is a video published on YouTube by the pharmaceutical company, BioCeuticals, which catches krill to turn into krill oil. I've posted this video because it gives you a flavour of the use of krill to humans.

What is interesting to note about this video is the way the company justifies its activities. Phrases like “krill is found in great abundance all around the Antarctic continent” and "the estimated biomass of Antarctic krill is twice the biomass of the worldwide human population"  indicates that krill are plentiful anyway so fishing would not create any disastrous ecological impacts. Also, the fact that the company interviewed a WWF Director demonstrates that they care about krill levels in Antarctica and want to engage in fishing in a sustainable manner.

Despite what this company claims about sustainable fishing, Antarctic krill populations have been declining. Figure 3a shows this steady decline. Even though there have been fluctuations since the 1970s, the general trend is a decrease in krill. Figure 3b shows where the krill populations have been declining and to what extent. In figure 3b, the red area indicates where the largest declines have occurred, which has been in the North. This region also happens to be the most accessible for ships because it is close to Argentina, making visits likely. As the video above showed, large ships travel to Antarctica to catch krill and turn them into oil almost immediately (while on the ship).

Figure 3. Krill population decline. 
a) Krill density in Antarctica from 1976 to 2000
b) Krill density across Antarctica
Source: Atkinson et al.(2004)

Indirectly, humans are having an impact on krill populations via climate change. Climate change is causing an increase in sea surface temperatures which is affecting the spawning and nursery areas of krill (Atkinson et al. 2004). According to Hill et al. (2013), sea surface temperatures have been increasing by 0.2^oC every ten years, but this is predicted to increase to warming of between 0.27^oC and 1.08 ^oC by the end of this century. Warmer sea temperatures are causing reduced sea ice extent which is problematic for krill because sea ice forms a large part of krill’s habitat. Atkinson et al. (2004) explains that sea ice also shields krill from predators and fosters sea algae, which are a key food source for krill. Additionally, climate change is exacerbating the destruction of their habitat because winter sea ice duration is reducing due to warmer temperatures and warmer oceans, thus humans are indirectly having a negative impact on krill.

So in this post, hopefully my readers have understood the importance of krill for Antarctic animals that feed on krill and have realised what negative impacts we are having on them, both directly and indirectly. The new scores are negative impacts 4, natural/positive impacts 2. Next week, I will discuss another indirect effect that humans have had on krill population.

Regulation Regulation Regulation

Is Montreal enough?

Are the Montreal Protocol and the general principles highlighted in Box 1 (from my post on Friday 14 November 2014) enough to remedy the potential negative wildlife impacts from tourism? This post is a discussion post where I will pick out and critically analyse some issues that I feel should be addressed going forward from the Montreal Protocol. You may also be pleased to know that this will be my final post about tourism!

The treaty has been criticised because there is no enforcement mechanism and because the tourism principles are non-binding (Lamers et al. 2012). There needs to be an enforcement mechanism otherwise governments will not take the principles seriously because they have nothing to lose if wildlife is negatively affected in Antarctica. Also, tourist companies need incentives to act to protect Antarctica. Without incentives created by governments, companies will feel relaxed about the limits because the short term gains are large and so they too lose nothing by disobeying the principles. Legally binding agreements and enforcement mechanisms are likely to make the Protocol more effective to help keep Antarctica in ecological equilibrium with minimal wildlife impact.

On a national scale, Argentina will lose out on tax revenues if business activities are restricted and Argentine tourist companies’ profits will fall. Tour companies that have to introduce mechanisms to reduce long-term degradation will incur costs, and revenues could fall if such mechanisms also add restrictions on tourist numbers. Because of this, profits will fall and so government tax revenues will also fall. The growth rate of the Argentine economy is currently 0.9% and over the past 20 years, the average growth rate has been only 0.84% (Trading Economics, 2014). These figures show that the Argentine government can greatly value the additional income that tourist companies generate for the country. Therefore if there is no enforcement mechanism, the government may be unwilling to act to ensure that the principles are met since this costs the economy. As can be seen, there is a strong economic element involved in regulating the Antarctic. In my opinion there should be an enforcement mechanism to encourage greater action to meet the goals the environmental standards proposed in Box 1 from my post on Friday 14 November 2014.

Environmental Impact Assessments (EIA)

Annex One makes it a legal requirement for tour companies to conduct an EIA. The document must describe the scale of tourism and the impacts that these tourists are expected to have. Furthermore, tour companies must outline how they are going to limit these impacts. There is a wide range of literature on whether EIAs actually improve conservation efforts. If risks have been identified and the company has included methods to mitigate against them, this does not necessarily mean that the environment is healthier than it was before the intervention. In other words, the environment will be healthier without tourism and human interference altogether because a set of mitigation rules mean reducing the impact, not necessarily avoiding it. This is my general critique of EIAs.

Secondly, Lyons (1993) argues that the language used in the Annex means that the “appropriate” level of assessment is open to interpretation. Annex One includes phrases such as “a minor or transitory impact”, “detrimental changes” and “significant changes”, which are vague and therefore each tour company and government are free to choose their own definitions of these phrases. This also makes it easier for them to make an excuse about why tourism activities have higher environmental impacts than the Protocol set. For example, a tour company can simply point out to the countries in the Antarctic Treaty that their definition of detrimental is more extreme and in their view, introducing one or two invasive species is not classified as “detrimental”. The vague wording therefore reduces the effectiveness of the Protocol.

Also, because of vague description of standards, Kriwoken and Rootes (2000) mention that it’s difficult to determine what should and shouldn't be measured as an impact of tourism. What this means is that there needs to be quantitative standards that allow tour operators to measure and monitor the exact impacts so they can better understand how they can adhere to the regulatory standards.

Sum up

The treaty doesn't signal to me that Antarctica is in safe hands. The lack of clarity in the wording of the actual treaty has to be addressed. Despite Bauer’s view that the Protocol is a barrier to future tourism development (1994), I feel that they are not strong enough because they have no binding or enforcing mechanism. This means that the environmental and wildlife problems arising from tourism will persist and we need more regulation regulation regulation.

Next time I move on to the effects that humans have had on Antarctic krill.

Antarctic Treaty

According Garrett Hardin (1968), each herdsman wants to keep as many cattle as possible. The rational herdsman decides that adding additional animal to his herd will increase his utility. But each herdsman shares the commons, so if each herdsman decides to keep increasing cattle to the commons, the end result will be the depletion and ruin of the commons.

The commons here can be compared to Antarctica. Antarctica is an unregulated area of land which yields benefits to tourist companies who want to keep increasing tourist numbers as each additional tourist yields these companies higher utility (i.e. higher profits). The main assumption that Hardin uses is that the commons is unregulated. In this globalised world, it is rare, in my view, to find an industry that is unregulated – especially when it comes to nature and the environment. What matters in this debate though, is not whether there are regulations but how effective the regulations are.

One solution to the negative impacts explained last week is to reduce tourist numbers. This could potentially reduce the introduction of invasive species and the impact on penguin habitats. But as is obvious in my post from 27 October, tourist numbers are rising and I think this solution is unlikely. Companies running expeditions such as Poseidon Expeditions, Quark Expeditions, Chimu Adventures are profit maximising companies. This means they want to make as much money as possible and so reducing passenger numbers is undesirable because this reduces revenues and profits. Nevertheless, the Antarctic Treaty endeavours to do just this. In recognition of greater human visits to Antarctica, the Antarctic Treaty has been set up to prevent an environmental catastrophe.

The Antarctic Treaty

It was formed in 1959 and came into force in 1961 to govern human activities. It comprises of 46 countries, of which 28 have advisory status (i.e. power to make decisions). The treaty believes that the following provisions are the most important (Secretariat of the Antarctic Treaty, n/d):

1. Antarctica shall be used for peaceful purposes only (Art. I).

2. Freedom of scientific investigation in Antarctica and cooperation (Art. II).

3. Scientific observations and results from Antarctica shall be exchanged and made freely available (Art. III).

It claims these are the most important, however on reading these, my first impression is that there is no mention of the environmental concerns. Research seems to be the main agenda. As you will read later in my blog, research centres can also have negative impacts on the continent. So this is one flaw that I spotted when I began researching the treaty.   

The Rules of the Treaty are known as the Antarctic Treaty System, consisting of three international agreements:

1. Convention for the Conservation of Antarctic Seals (1972)

Aims to reduce commercial exploitation of seals.

2. Convention on the Conservation of Antarctic Marine Living Resources (1980)

Aims to conserve and manage marine living resources in Antarctic. The following measures, among others, are being taken (Fabra and Gascon, 2008):

a. Develop a management regime for krill that takes into account the impact of fishing on dependent species

b. Establish a monitoring program

c. Develop fisheries management policies

3. Protocol on Environmental Protection to the Antarctic Treaty/ Montreal Protocol (1991)

Protocol on Environmental Protection to the Antarctic Treaty/ Montreal Protocol

The relevant agreement that relates to tourism is number 3: Protocol on Environmental Protection to the Antarctic Treaty. This protocol was established in 1991 once it was recognised that the number of tourists were increasing. This treaty is broken up into six annexes including:

1. The requirement of an environmental impact assessment/initial environmental evaluation for every activity before it’s due to start 

2. Rules concerning the conservation of fauna and flora 

3. Rules on waste disposal and waste management 

4. Rules on marine pollution 

5. The establishment of protected areas 

6. Preventative measures and contingency plans shouldoperate in case of an environmental disaster. 

(Accessed through: Secretariat of the Antarctic Treaty, 2011)

Of the Annexes, number three and number six mention tourism. There were previously no restrictions or regulations on tourism, but this changed in 2009 when an agreement was made among member countries to limit tourism by reducing the size of cruise ships, capping the number of passengers that land in Antarctica to 500 and capping passengers on the shore at any given time to 100 (BBC, 2009). This agreement was discussed in the Antarctic Treaty Consultative Meeting in Baltimore. Box 1 displays the general principles that came out of these discussions.

Box 1: General principles of Antarctic tourism agreed in 2009
Source: Lamers et al. (2012)

So hopefully from this post I have illustrates that action is indeed being taken to help reduce the human impacts on Antarctica. The international community is not ignoring what is happening to wildlife in Antarctica and it’s important to acknowledge this. International treaties help regulate and reduce negative environmental issues. In particular, Annex 3 which relates to waste management is a useful starting point to improve the environment. 

This is where I’m going to end today. Because regulation aims to reduce the human impact, this is one point to positive impacts, so the updated score for negative impacts vs natural/positive impacts is 3-2. These treaties signify that we acknowledge and want to reduce our wrong doings. But are these really effective? Keep a look out for the next post where I will determine whether its one more point to negative impacts or not.

Holidaying in Antarctica II

This post is about even more impacts that tourism has had on the Antarctic environment.

Oil Spills

Oil spills that have occurred in Antarctica have never been of the same magnitude as oil spills that occur from oil pipe leakages such as the BP oil spill in 2010, where 210 million gallons of crude oil was spilt (The Telegraph, 2011), or the Little Buffalo oil spill in Canada that occurred in 2011, spilling more than 800,000 gallons (Yahoo News, 2014). Nevertheless, this does not mean that they don’t have severe consequences when they occur. If anything, oil spills have an even worse effect because marine life here is much less adaptable and rarer. 

When ships travel down to Antarctica they sometimes have oil spills. The frequency of oil spills is shown in table 1, along with a summary of their impacts on wildlife.

Source: Aronson et al. (2011)

From the table, it is clear that oil spills in Antarctica don’t happen as often as the spills that appear in the news from drilling sites. Over the past 30 years, Aronson et al. (2011) seem to report just five spills. Interestingly, all of the reported oil spills have occurred during Antarctica’s summer, confirming that these are impacts from tourism. Some of these oil spills had no reported effects, demonstrating that there should be no concern about tourism related oil spills, right?

Not quite! The reason why oil spills in Antarctica are problematic is that Antarctica does not have infrastructure to deal with oil spills properly. They don’t have infrastructure to undertake large scale clean-up operations or clean up oil soaked mammals. Moreover it is difficult to conduct these operations because of harsh conditions during the winter. Because of this, the effects of large oil spills can have long run impacts of marine and terrestrial wildlife.

Bahia Paraiso

The largest oil spill that happened was when the Bahia Paraiso tourist ship sank, carrying 130 tourists (but luckily they all evacuated just before the sinking!). The wildlife impacts of this spill were significant. The South Polar Skua, pictured in figure 1, is a sea bird found prominently in Antarctica. Antarctica is the bird’s natural habitat. Following the oil spill in 1989, the mortality rate among this bird species increased sharply and remained high while the oil was present. This could have been because the birds feed on krill and fish, both of these were chemically contaminated as a result of the spill. Young chicks were affected the most, with all of the chicks of a sample of 53 nests dying during the spill in December (Eppley and Rubega, 1990).  One reason for this was that parents had been fouled by the diesel oil when they went out looking for food in oil slicks (where fish and krill are found). Because of this, they spent more time away from their nests to bathe in freshwater ponds before returning to their nests. In the meantime this left young chicks unprotected and vulnerable to attack by other skuas. This affect was widespread and affected the entire population.

Figure 1: South Polar Skua

Other effects of this oil spill include the transfer of oil from parents to young or from prey to predator; changes in food availability due to effects on other populations and toxicity resulting in mortality of Adélie penguins. 

So the bottom line is that oil spills are catastrophic to wildlife in Antarctica and wouldn’t even happen if it wasn’t for all those tourists and tourist companies making careless mistakes. The new score is negative impacts: 3, positive/natural impacts: 1.

Again, I understand this post may be slightly depressing, so I would like to end with a few positive points. I came across the ytravel blog which includes a page about Antarctica. Along with a great selection of photos of Antarctica, it also includes a list of reasons to visit Antarctica! It can be accessed by clicking here. Also, my next post will be about how Antarctic treaties and international laws are trying to protect Antarctica – it’s not all doom and gloom! Until then, I’m going to leave you with a short video to brighten up this post, illustrating why we should celebrate the wildlife in Antarctica. Although note - it seems that some of the clips were videoed by tourists!

Edit: If you would like to know more about tourism in Antarctica, Fiona has a wonderful post about it and also gives her perspective on tourism. Here is a link to her blog.

Holidaying in Antarctica

Antarctica has become a popular tourist destination over the years. First starting in the 1950s, expedition cruises take tourists to see the wildlife, unique scenery and geology, and visit research centres. Nowhere else on Earth can visitors can go to a continent totally surrounded by the sea and observe some of the world’s rarest species in some of the world’s harshest conditions. These are all reasons why tourism is gaining momentum and why the tourist season has increased to 173 days per year (Aronson et al. 2011). But how is the tourism industry affecting the wildlife in Antarctic?

Penguins

Before the 1950s, wildlife in Antarctica was not used to seeing humans in their habitats very much. Human activity was mainly focussed on research and so a lot of human activity was conducted in research centres – no one was actively looking for penguins or seals or whales. Now that they are, some penguin species are reacting to them, while others are not.

I found this funny cartoon, portraying this point:

Figure 1. Adapted from Antarctic-monument.org  

Seventeen species of penguins can be found on Antarctica. Of these, there are four penguin species that breed on the Antarctic continent itself: the Adelie, the Emperor, the Chinstrap and the Gentoo penguins (Antarctic Connection, 2014). Lynch et al. (2010) conducted a study on Petermann Island (see figure 3) which found that the Gentoo penguin has shown a reduction in breeding productivity in areas where tourists frequently visit. One explanation for this could be that they are less likely to establish a nest in areas that are frequently visited. Although correlation does not mean causation, it’s in my view that tourist visits has played a role in their population because visiting their habitats can be unsettling.

In spite of this, surprisingly Lynch et al. (2010) also found in their study that the Adélie penguin was not affected by frequent tourist visits in terms of breeding. This shows that the effect of tourist visits is species specific and therefore can be difficult to measure. Figure 2 shows the penguins.

Figure 2. Gentoo penguin (left) and Adélie penguin (right)

The Lynch et al. (2010) paper was very insightful to read. Even though I read it to learn about the impacts of tourism on the breeding productivities of the Adélie and Gentoo penguins, I also learnt about a new potential human cause of a trending population decline of the Adélie penguin. During their study, the authors realised that there was a tick infestation among the Adélie penguin colonies at Petermann Island in North West Antarctica, a popular tourist destination because of its proximity to the southern tip of Argentina. This is shown in figure 3. The fact that tourists frequently visit the Island can help explain the spread of this I. uriae parasite. The evidence leads me to believe that the I. uriae parasite was transported from another North Western Island because the authors point out that this was the first time they had witnessed it on Petermann Island since they started investigating penguins there twenty years ago. This demonstrates that tourist expedition cruises may have transported it from another island. The authors also mention that they can’t rule out that climate change could have created conditions allowing its existence in this region. Either explanation holds humans responsible, at least in part, of this occurrence.

Figure 3: Petermann Island

Invasive species

This leads me nicely to my next topic about how tourism causes the invasion of foreign species. Tourist ships tend to contain double hulls. This is a cause of concern because double hulls provide insulation against temperature reductions as ships make their way to Antarctica, allowing invasive species to survive. An example of an invasive species is the mussel species, Mytilus Galloprovincialis, which was observed to have survived in a sea chest on a supply ship by Lee and Chown (2007). Another invasion species found is a type of green algae called Enteromorpha Intestinolis which was discovered growing on Half Moon Island off the West Antarctic Peninsula, apparently because it was transported there by tourist vessels (Clayton et al., 1997; Aronson et al., 2011). These invasive species can be problematic because they affect the food chain, invade habitats and can potentially initiate and spread new diseases to existing marine wildlife. The latter effect is demonstrated by the tick infestation found on Petermann Island. 

All in all, it seems that tourism in Antarctica is having a somewhat damaging effect on wildlife. Understanding these impacts have actually put me off wanting to visit Antarctica for a holiday, then again, I don't think I would be able to survive the cold anyway! So far, the scores for negative human impacts verses positive/ natural impacts on Antarctica are 2-1.

Apologies for such as negative post! Sometimes the impacts of humans on wildlife are harmful and I am trying to shed light on this. My next post will be about oil spills from tourist ships and how this affects sea birds and other wildlife. So until then, thanks for reading!