The University of Southampton

Tag: Environmental Change

Turmoil in the Tundra: the Cold Hard Truth

Posted on by Nikol Raykova

A harsh, cold land with no tree cover, temperatures averaging between -12 to -6 degrees Celsius, and enveloped in snow for the majority of the year (National Geographic, 2017).

Until the brief summer months bring warmth and plains become decorated with swathes of wildflowers. This is the tundra biome.

 

screen-shot-2017-03-22-at-22-35-14

                                        Figure 1: Arctic animals

 

A home to many endearing (and endangered) animals like the Arctic fox, snowy owl, lemmings and grey-wolves (Figure 1) (National Geographic, 2017). But why should we care about some cold desolate place? The answer is simple yet complicated.

It comes down to the ever looming climate change disaster. The Arctic tundra has been recognised as one of the most vulnerable biomes to environmental change. Permafrost (permanently frozen ground) covers much of the tundra, with the top 30cm or so of it melting and refreezing with the changing seasons (NOAA, 2017). However, in the last few decades increasing global temperatures, and human developments have lead to more melting. This can have a negative effect on the ecosystem as the more permafrost that’s melted, along with the later arrival of the autumn freeze time means that shrubs and other vegetation, that couldn’t take root before, can now grow, potentially altering the habitat (Heijmans et al 2016).

screen-shot-2017-03-22-at-21-44-41

Figure 2. Different types of interactions within an Arctic tundra ecosystem. Solid lines = consumption between predator and prey between trophic levels (different parts of the food web Dotted lines = interaction between species in the same trophic level (same part of the food web) (Ims and Fuglei, 2005).

 

Northward expansion of Low Arctic trees and shrubs has been seen due to the warmer temperatures and longer growing seasons. This has other ecological consequences, like change in the biodiversity of an area if new species are introduced (Post et al., 2009). Overall ecosystem structure change has been recorded in multiple studies, including interaction between animal species (Hobbie et al 2017).

Although they may be cute and fluffy Arctic foxes are one of the key species within Arctic tundra ecosystems because they are a top predator, meaning they help control herbivore populations (Figure 2). It’s been seen that where abandoned Arctic fox dens are found, the productivity of that area (i.e. plant growth, number of insect and herbivores etc.) has increased (Killengreen et al., 2007).

A study by Ims and Fuglei, (2005) has shown that lemmings are also key players in the Arctic tundra. These rodents are a key prey species for a number of predators that rely on certain densities of lemming populations to allow them to reproduce, as they need sufficient amount of food. Lemmings breed during the winter season and undergo growth under the snow, leading to a peak in population density in spring. This means that with predicted warmer winters (hence less snow, and more rain) lemming peak times are very likely to alter, with population peaks happening during autumn (Putkonen and Roe, 2003). A change in the number of prey available, will impact predator numbers. Arctic fox and snowy owl numbers are likely to decrease as they will have lower reproductive rates during years when peak lemming populations occur autumn.

A change in the relationships between key species like this can have unprecedented effects on their communities and ecosystems. With a grim future ahead for cold-loving animals and ecosystems.

 

 

References

National Geographic, (2017). Explore the World’s Tundra. Available at: http://www.nationalgeographic.com/environment/habitats/tundra-biome/ [Accessed 17 Mar. 2017].

NOAA (2017). Arctic Change – Land: Permafrost. Available at: https://www.pmel.noaa.gov/arctic-zone/detect/land-permafrost.shtml [Accessed 17 Mar. 2017].

Post, E., Forchhammer, M. C., Bret-Harte, M. S., Callaghan, T. V., Christensen, T. R., Elberling, B., … & Ims, R. A. (2009). Ecological dynamics across the Arctic associated with recent climate change. Science, 325(5946), 1355-1358.

Ims, R. A., & Fuglei, E. V. A. (2005). Trophic interaction cycles in tundra ecosystems and the impact of climate change. Bioscience, 55(4), 311-322.

Killengreen, S. T., Ims, R. A., Yoccoz, N. G., Bråthen, K. A., Henden, J. A., & Schott, T. (2007). Structural characteristics of a low Arctic tundra ecosystem and the retreat of the Arctic fox. Biological Conservation, 135(4), 459-472.

Putkonen J, Roe G. 2003. Rain-on-snow events impact soil temperatures and affect ungulate survival. Geophysical Research Letters 30: 1188.

Heijmans, M. M. P. D., van Huissteden, J., Li, B., Wang, P., Limpens, J., Berendse, F., & Maximov, T. C. (2016). Can wet summers trigger permafrost collapse at a Siberian lowland tundra site?. INTERNATIONAL CONFERENCE ON PERMAFROST, 2016-06-20/2016-06-24

Hobbie, J. E., Shaver, G. R., Rastetter, E. B., Cherry, J. E., Goetz, S. J., Guay, K. C., … & Kling, G. W. (2017). Ecosystem responses to climate change at a Low Arctic and a High Arctic long-term research site. Ambio, 46(1), 160-173.

 

Word count [496]

 

 

 



Going with the Flow? How ‘friendly’ are Dams really?

Posted on by Elizabeth Henderson

With a growing global population, dams are more relied on than ever to provide electricity and secure land; with over 45,000 >15m tall dams existing globally (World Commision.2005), and mans’ intrusion on biodiversity being a well-known threat (MEA, 2005a), dams may not be as environmentally friendly as they seem.

Dams ultimately obstruct water ways, breaking up continuous systems and causing a number of effects due to their construction (Collier 1996). Like sticking tape across guitar strings; it will still play music, but not to the same extent. They do so in 4 main ways(Ligon 1995):

  • Water flow
  • Sediment
  • Nutrients
  • Energy
  • Biota

 

Water flow is slower upstream due to the build-up of water, which can lead to the creation of reservoirs, an entirely new Ecosystem. The rivers, are more likely to host large plant populations and a different community of organisms (typical of higher order rivers), at much lower orders (Figure.1).
Downstream flow is regulated by the dam itself, and so changes on location. But typically reduce peak flows that provide erosion and creation of sediment downstream (McCartney 2009).

Dams are nutrient and sediment sinks, inhibiting what’s carried downstream. Reducing the flow of all particles to downstream systems, and increasing their build-up in upstream systems, causes different shifts in their Ecosystems. High nutrients upstream puts systems at risk of Eutrophication (a swift increase in phytoplankton blocking sunlight to larger plants, causing substantial loss of oxygen and life), but the loss of material downstream can cause other changes (Figure.2).

The unification of the McKenzie river before (darker blue, 1969) and after (light blue, 1980), which caused in the loss of habitat via islands and sheltered streams, resulting in a 50% decrease in salmonids
The unification of the McKenzie river before (darker blue, 1969) and after (light blue, 1980), which caused in the loss of habitat via islands and sheltered streams, resulting in a 50% decrease in salmonids (Ligon 1995)

Energy includes temperature. Larger reservoirs can become stratified, making specific levels: An upper, warmer, oxygen rich layer and a lower, colder, high nutrient and low-oxygen layer. Dam outflow can come from either of these levels, which effects what occurs downstream. Any change in temperature often puts areas at odds with what it should be for seasonal levels, such as reducing fish growth and plant productivity if lowered (McCartney 2009).

With Biota, fish community migration is the main issue. This mainly refers to the reproduction cycles of migratory fish, such as salmonids, which reproduce in highland areas after migrating upstream. Many dams introduce fish ‘ladders’ in which the fish can ‘jump’ upstream, and others such as the ‘fish cannon’ (see video) or bristle walkways for hagfish. However the main problem is fish can’t typically find the entrance.

Freshwater Ecosystems are more diverse per m2 than both land and marine biomes (MEA 2005b), to sustain this diversity, regional change across the entire river system needs to be present (MEA 2005a). Heavily dammed rivers (e.g. 25), such as the Snake and Columbia Rivers, USA, have ecosystems vastly different from unmodified rivers, causing the loss of its Sockeye and Chinook Salmon (Collier et al 1996). This also causes a similarity of conditions, which increases the risk of invasive species, as they can compete better in ‘more general’ ecosystems (Olden, 2006).

Overall Dams vastly impact river ecosystems, a brief few have been highlighted, but needless to say there are many more, they’re not so ‘friendly’ after all.

.

 

References

Word Count: 499

Collier, M., Webb, R.H. & Schmidt, J.C. (1996) Dams and Rivers: A Primer on the Downstream Effects of Dams

[David] (06, February, 2011) River Continum, Retrieved from URL: http://yorkshiredalesriverstrust.blogspot.co.uk/2011/02/ecology-of-river-changes-as-you-move.html

Ligon, F.K., Dietrich, W.E. & Trush, W.J. (1995) Downstream Ecological Effects of Dams, BioScience, 45(3): 183-192

McCartney, M. (2009) Living with Dams: Managing the Environmental Impacts, Water Policy, 11(1): 121-139

Millenium Ecosystem Assessment (2005a) Ecosystems and Human Well-being: Biodiversity Synthesis, World Resource Institute, Washington, DC

Millenium Ecosystem Assessment (2005b) Ecosystems and Human Well-being: Wetlands and Water Synthesis, World Resource Institute, Washington, DC

Naiman, R.J., Decamps, H. & McClain, H.E. (2005) Riparia: Ecology, Conservation, and Management of Streamside Communities, Elseiver, New York

Olden, J.D., LeRoy Poff, N. & Bestgen, K.R. (2006) Life-History Strategies Predict Fish Invasions and Extirpations in the Colorado River Basin, Ecological Monographs: Ecological Society of America, 76(1): 25-40

[Tech Insider] (2017, 3rd Feburary) Salmon cannon gives fish a boost over dams, Retrieved from: https://www.youtube.com/watch?v=xIB2616zcLk

World Commissions on Dams (2000) Dams and Development: A New Framework for Decision-Making, Earthscan Publications, London



Could crop and tree diseases completely alter the world we live in today?

Posted on by Holly Moser

Imagine Winnie the Pooh without One Hundred Acre Wood, Robin Hood without Sherwood Forest or Baloo without his prickly pears.

This cartoon was created to illustrate how all the trees were chopped to stop a 'killer fungus' (Adams, 2012)
This cartoon was created to illustrate how all the trees in the One Hundred Acre Wood were chopped down to stop a ‘killer fungus’ (Adams, 2012)

Back to the real world 

Acute oak decline Symptom: Profuse stem bleeding (Forestry Commission, 20170.
Acute oak decline
Symptom: Profuse stem bleeding (Forestry Commission, 2017).

The facts are that oaks are being decimated by acute oak decline (Forestry Commission, 2017), pears by fire blight (Johnson, 2000) and the Woodland Trust estimates that the UK could lose 130 million ash trees (Woodland Trust, 2017). These plants are part of our culture and economy but imagine how much worse it would be if you lived in the developing world and your staple diet was at risk.

Rice, the basic diet of half of the world’s population (FAO, 2013), is under threat from a serious disease called rice blast. Silicon is rice’s natural ‘knight in shining armour’ shielding it from this pathogen. Elevated CO2 levels are expected to decrease the plants silicon production, leaving rice vulnerable to its arch enemy and reducing overall yield (Elad and Pertot, 2014).

 

Invasion of the north

Scientists expect some pathogens such as Phytophthora cinnamomi  one of the world’s most invasive species to shift northwards due to warmer and wetter winters increasing the chance of overwinter survival in areas that are currently unsuitable (Burgess et al., 2017).

Although drier summers should have a counteracting effect, trees that have already been infected by P.cinnamomi are less likely to recover due to a reduced ability to take up water by rotting roots and increased drought stress (Burgess et al.,2017).

A map of the areas where P.cinnamomi already exists and the areas that may become more or less suitable for the invasion of P.cinnamomi with regards to future climate change.
A map of the areas where P.cinnamomi already exists and the areas that may become more or less suitable for the invasion of P.cinnamomi with regards to future climate change (Burgess et al., 2017).

Researchers are working against the clock to create new fungicides and develop disease resistant crops but these interventions appear to have some worrying knock on effects.

For example, researchers from the University of Exeter thought they might have a solution to ash dieback by breeding from older, resistant trees. However, it was recently discovered that that these older trees produce fewer chemicals to ward off the deadly emerald ash borer (University of Warwick, 2017). A double strike from ash dieback and emerald ash borers could wipe out ash in the UK!

Illustration of the Emerald ash borer and the damage it can cause to ash trees (Clark, 2013).
Illustration of the emerald ash borer and the damage it can cause to ash trees (Clark, 2013).

The news is not all bad

Although Baloo may lose his prickly pears, not all diseases are expected to increase with climate change and he may gain bananas. One disease expected to decrease in severity and frequency reducing the impact it has on global yield is black sigatoka a disease which decreases the leaf area in bananas reducing photosynthesis (Elad and Pertot, 2014 & Ploetz, 2001).

So where does that leave us?

There are still many gaps in plant disease research involving mechanisms of infection, resistance and the affect on plant function. There are also many unanswered questions- could a decrease in one disease kick off the invasion of another? Such factors make it impossible to predict the exact change to our landscape and crops. But the simple answer to my question is yes. Unless plant disease research achieves some major breakthroughs the chances are that our landscape will look very different and we may need to develop a taste for new foods.

 

 

References

Adams, 2012. Cartoon: One Acre Wood. Available from: http://www.englishblog.com/2012/10/cartoon-one-acre-wood.html#.WNMBBG-LTIX  [Accessed on: 16/03/2017].

Burgess, T.I., Scott, J.K., McDougall, K.L., Stukely, M.J.C, Crane, C., Dunstan, W.A., Brigg, F.,Andjic, V., White, D., Rudman, T., Arentz, F., Ota, N. and Hardy G.E.ST.J., 2017. Current and projected global distribution of Phytophthora cinnamomi, one of the world’s worst plant pathogens.  Global Change Biology; 23: 1661-1674.

Clark, P., 2013. Health and Science: The emerald ash borer’s domino effect on human health. Available from: http://www.washingtonpost.com/wp-srv/special/metro/urban-jungle/pages/130514.html [Accessed on: 21/03/2017].

Elad, Y. and Pertot, I., 2014. Climate change impacts on plant pathogens and plant diseases. Journal of crop improvement; 28 (1): 99-139.

FAO, 2013. FAO statistical year book 2013: world food and agriculture. FAO statistical year books, Rome, FAO: p.132. Available at: http://www.fao.org/docrep/018/i3107e/i3107e.PDF [Accessed on: 22/03/2017].

Forestry Commission, 2017. Acute Oak Decline. Available from: https://www.forestry.gov.uk/acuteoakdecline [Accessed on: 21/03/2017].

Johnson, K.B. 2000. Fire blight of apple and pear. The Plant Health Instructor. DOI: 10.1094/PHI-I-2000-0726-01. Updated 2015.

Ploetz, R.C. 2001. Black sigatoka of banana: The most important disease of a most important fruit.  The Plant Health Instructor.  DOI: 10.1094/PHI-I-2001-0126-02. Available from: http://www.apsnet.org/publications/apsnetfeatures/pages/blacksigatoka.aspx [Accessed on: 22/03/2017].

University of Warwick, 2017. Ash dieback- insect threat to fungus- resistant trees. Available from: https://phys.org/news/2017-01-ash-diebackinsect-threat-fungus-resistant-trees.html [Accessed on: 16/03/2017].

Woodland Trust, 2017. Protecting landscapes. Available from: https://www.woodlandtrust.org.uk/visiting-woods/tree-diseases-and-pests/what-we-are-doing/protecting-landscapes/ [Accessed on: 21/03/2017].

Word Count: 494



Diamonds aren’t Forever, as Villainous Tourists have a ‘License to Kill’ the World’s Coral Reefs

Posted on by Thomas Manktelow

Tourism is killing coastlines worldwide, destroying crucial coral reefs and the immense diversity within these ecosystems. Humans are irreversibly changing the marine environment!

There is a modern urge to travel the world; tropical, coastal areas increasingly visited for the sun and climate. More money in these regions puts natural systems at-risk, increased development and uncontrolled tourism affecting ecosystems such as coral reefs. Tourism has the ability to severely degrade coral reefs, introduced below (4earthTV, 2016).


Akumal Case Study

Akumal, Mexico, is an example of a coastline and reef ravaged by tourism. The number of hotel rooms in the region has increased by 80,000 in the last 30 years (Gil et al, 2015).
I have seen for myself the extent of the local environment change, which has had obvious negative effects on the health of the Mesoamerican barrier reef (BBC Earth, 2014).

In Akumal’s popular snorkeling areas, coral cover declined by 79% between 2011 and 2014. Globally, holiday activities have negative effects on the coral and on the native reef species (Gil et al, 2015). Turtle and shark populations suffer increased stress as tourism and tourists dominate the coastline (Constantine, 2001). Coral reefs are very sensitive to rapid tourism development, the popularity of these areas increasing algal cover and coral disease in the community (Garpow, 1999).

Tourism and boat traffic in Akumal Bay, Akumal (Photo: J. Houston)
Tourism and boat traffic in Akumal Bay, Akumal (Photo: J. Houston)

Hotel Pollution

Another consequence of global change are the septic tanks from growing hotel complexes, which feed coral reefs with nutrients, boosting the growth of algae and negatively changing the system. This clouds the water, meaning sunlight cannot reach the coral, causing unhealthy reef conditions (Garpow, 1999). Tourists are a huge environmental change impacting coral reefs. Coastal resorts attract the greatest number of tourists annually, often because of our growing desire to view coral reefs (Davenport & Davenport, 2006).

 

SCUBA Divers and Snorkelling

Worldwide, SCUBA divers and swimmers can severely damage the reef – in crowded areas, coral contact can lead to 100% mortality (Reef Resilience, 2016), inflicting abrasion and tissue loss (Davenport & Davenport, 2006). Tourists can also suffocate the coral, stirring up silt and encouraging algal domination. Coral reefs are also experiencing more boat traffic, which can disrupt coral communities, upsetting species interactions. Using boat anchors on the reef can damage the coral for decades, lowering reproductive health and species fitness (Rogers and Garrison, 2001).

Left: Snorkeler touching native turtle (Photo: J.Bartoszec, 2010). Right: Brain coral suffering anchor damage (Photo: Z. Livnat)
Left: Snorkeler touching native turtle (Photo: J.Bartoszec, 2010). Right: Brain coral suffering anchor damage (Photo: Z. Livnat)


The Future of Coral Reefs

There are global plans to increase tourism around coral reefs, building additional hotels. Human pollution will increase; sun-cream and E. coli contamination expected to impact reef health. Marine turtles are also developing tumours from a tourism-borne virus, demonstrating the reduced health of coral reefs and the species within them; all because of tourism (Sanchez-Navarro Russell, 2016).

Coral reefs across the world are experiencing problems associated with tourism. Fifty years ago reefs were untouched; only in the last 30 years have coral reefs become a primary tourist attraction. The coastline has changed so dramatically that slow-growing coral and the species within them cannot adapt fast enough and are suffering greatly.

Tourism has the potential to kill existing coral reefs; therefore, it is our responsibility to manage coastlines with greater effect, and as tourists, show greater respect towards the marine environment.

 

[483 words]

 

References

BBC Earth. (2014). The Struggle to Save the Caribbean’s Huge Barrier Reef. Available: http://www.bbc.co.uk/earth/story/20141128-the-other-great-barrier-reef. Last accessed 13th March 2017

Constantine (2001), Increased Avoidance of Swimmers by Bottlenose Dolphins (Tursiops truncatus) due to Long-Term Exposure to Swim-With-Dolphin Tourism, Marine Mammal Science. 17 (4), p689-702.

Davenport and Davenport (2006), Impact of Tourism and Personal Leisure Transport on Coastal Environments: A Review. Estuarine, Coastal and Shelf Science. 67, p280-292.

Garpow, W (1999), Sustainability Indicators Regarding Tourism Development and Coral Reef Conservation: A Case Study of Akumal in the Caribbean, Proceedings of the 1999 Northeastern Recreation Research Symposium. P23-29.

Gil et al (2015), Rapid Tourism Growth and Declining Coral Reefs in Akumal Mexico, Marine Biology. 162 (11), p2225-2233

Reef Resilience (2016), Tourism and Recreational Impacts. Available: http://www.reefresilience.org/coral-reefs/stressors/local-stressors/coral-reefs-tourism-and-recreational-impacts/. Last accessed 13th March 2017.

Rogers and Garrison (2001), Ten Years after the Crime: Lasting Effects of Damage from a Cruise Ship Anchor on a Coral Reef in St. John, U.S. Virgin Islands. Bulletin of Marine Science. 69 (2), p793-803.

Sanchez-Navarro Russell (2016), Akumal Suffering from Unsustainable Growth. Available: http://mexiconewsdaily.com/opinion/akumal-suffering-from-unsustainable-growth/. Last accessed 13th March 2017.

4earthTV. (2016). Coral Reef Conservation: 4earthTV. Available: https://www.youtube.com/watch?v=OGcnzggMqKA. Last accessed 22nd March 2017.