The University of Southampton

Month: March 2017

Fuelling the Fire of Climate Change

Posted on by Lara Jackson

Human activities are fuelling the fire of climate change!

Whether it’s caused by us, or exacerbated by our actions, climate change is real and it’s one of the biggest threats to ecosystems and species on earth!

Climbing global temperatures are changing weather patterns, resulting in more frequent, adverse events, such as droughts and wildfires [figure 1](Campbell et al, 2014). The scale of such environmental disturbances can be influential in determining the composition and structure of biological communities (Campbell et al, 2014).

An example of a forest wildfire.
Figure 1 – Up in flames: A wildfire burns voraciously in Arizona, USA. Available: http://wildlife.org/wildfire-toward-understanding-its-effects-on-wildlife-from-the-wildlife-professional/

A community is an assemblage of organisms of differing species that inhabit the same geographical area (Campbell et al, 2014).

 

Wildfires destroy communities that aren’t adapted to such large-scale environmental changes (Campbell et al, 2014). Although they do occur naturally, rapid land-use change, El Niño events and droughts are extending the wildfire season, intensifying the impacts in tropical environments (Campbell et al, 2014).

Fires negatively affect the biodiversity of tropical forests as they destroy the climax community; following the fire, generalist and broadly-distributed species are selected for because these pioneer species can tolerate the harsh, burnt conditions (Campbell et al, 2014). This, coupled with the increased penetration of sunlight to the forest floor, means that they dominate the under-storey, reducing the species diversity of the growing vegetation (Cochrane et al, 1999).

Furthermore, fires reduce the abundance of flowering and fruiting trees; this deters animal species which would usually be attracted to such flora from re-inhabiting the area, thus, seeds are not dispersed and the recovery of the forest is even slower (Campbell et al, 2014). In 1997-1998, 5 million hectares of tropical forest and 70% of seedlings and saplings were destroyed in Sumatra (Kinnaird et al, 1998). Subsequently, there were observable decreases in the abundance of frugivores like siamangs (Hylobates syndactylus) seen in figure 2 (Campbell et al, 2014).

A Siamang (Hylobates syndactylus), the largest of the gibbon family that experienced population declines following severe forest fires in Sumatra. Available: http://www.houstonzoo.org/blog/see-the-siamangs-like-never-before/
Figure 2 – Siamangs (Hylobates syndactylus), are the largest of the gibbon family. They experienced significant population declines following severe forest fires in Sumatra between 1997-1998 when 5 million hectares of their home was burnt to a crisp! Available: http://www.houstonzoo.org/blog/see-the-siamangs-like-never-before/

Three years after a forest fire in Brazil, there were noted increases in the sensitivity of insectivorous birds to the consequential changes in forest composition (Barlow et al, 2004). Hence, fires also displace numerous animal species that live within the forests, disrupting ecological interactions, like food-webs, that maintain biological processes (Campbell et al, 2014). Furthermore, correlations were found between burn severity and tree mortality rates after the wildfire, leading to significant changes in forest structure (Barlow et al, 2004).

The increasing frequency of wildfire events and the subsequent disturbance to the environment has the potential to cause unparalleled changes in the composition of tropical forest communities (Cochrane et al, 1999). Not only do fires severely impact the structure and quality of the flora, they decrease the species diversity of vegetation present in the forest and result in declines in abundancy of fruiting and flowering plants. Furthermore, they have knock-on consequences for the fauna inhabiting the forest. Animals are displaced, biological interactions and processes are disrupted and frugivore and bird populations decline. To reduce the large-scale environmental changes caused by wildfires, we must adjust our habits to slow the rate of climate change and moderate the impacts of global warming.

 

References:

Barlow, J. & Peres, C.A. (2004) Ecological Responses to El Nino-induced Surface Fires in Central Brazilian Amazonia: Management Implications for Flammable Tropical Forests. Philosophical Transactions of the Royal Society B, vol 359(1443):367-380

Campbell, N. Reece, J. et al (2014). Biology: A Global Approach. Pearson Education Limited. Tenth Edition.

Cochrane, M.A. & Schulze, M.D. (1999). Fire as a Recurrent Event in Tropical Forests of the Eastern Amazon: Effects on Forest Structure, Biomass and Species Composition. Biotropica, vol 31(1):2-16

Kinnaird, M.F. O’Brien, T.G. (1998) Ecological Effects of Wildfire on Lowland Rainforest in Sumatra. Conservation Biology, vol 12(5):954-956


Word Count: 499



Living on the Edge: Habitat Fragmentation in Our Rainforest Ecosystems

Posted on by Leah Line

The Brazilian Atlantic rainforest is made up of some of the most important ecosystems on earth (Magnago et al., 2014). It supports species that are not found anywhere else on the planet (Ribeiro et al., 2009). However, the rainforest is not the vast expanse of green canopy that you might imagine.

In fact, deforestation has divided the landscape. Now, more than 80% of the remaining forest is made up of fragments with an area of less than 50 hectares (Ribeiro et al., 2009). Almost half is less than 100 metres from its edges (Ribeiro et al., 2009).

Deforestation leads to isolated fragments of rainforests. Source: Bierregaard, 2016
Deforestation leads to isolated fragments of rainforests. Source: Bierregaard, 2016

The situation in the Brazilian Atlantic rainforest is not uncommon. Due to fragmentation, more than 70% of the world’s forests are now within 1 kilometre of a forest edge, impacting rainforest ecosystems across the globe (Haddad, 2015).

WHAT IS HABITAT FRAGMENTATION?

Habitat fragmentation is the division of a habitat into increasingly smaller and more isolated pieces (Haddad, 2015). In rainforest ecosystems, this is done through deforestation. Fragmentation effects the entire ecosystem, by reducing forest area, increasing isolation and increasing forest edges (Haddad, 2015).

EDGE EFFECTS

Edge effects are the ecological changes that occur at the boundaries of these habitat fragments (Laurance et al., 2016). They can include (Laurance et al., 2016)

–  Increased wind damage
–  Changes in temperature and humidity
–  Increased flooding

These effects may make the environment along the edges of fragments unsuitable for certain species, making their available habitat even smaller (Turner, 1996).

As forests become increasingly fragmented, their exposure to edge effects also increases. Source: www.summitlearning.org
As forests become increasingly fragmented, their exposure to edge effects also increases. Source: www.summitlearning.org

THE HABITAT MATRIX

The landscape surrounding forest fragments is referred to as a “matrix” of habitats (Haddad, 2015; Gascon et al., 1999). The matrix plays an important role in acting as a selective filter for the movement of species between fragments (Gascon et al., 1999). Animals that cannot survive the matrix will be unable to move across fragments. This not only makes the animals themselves at risk of decline, but if they play a role in seed dispersal (by transporting plants’ seeds in their faeces, fur or feathers) plants will also be at risk.

“Why did the cassowary cross the road? To disperse seeds.” Cassowaries are important for seed dispersal in the rainforests of New Guinea, but could be threatened due to fragmentation of their habitats. Source: Roberts, 2016
“Why did the cassowary cross the road? To disperse seeds.” Cassowaries are important for seed dispersal in the rainforests of New Guinea, but could be threatened due to fragmentation of their habitats. Source: Roberts, 2016

But, it is not all bad news: studies have found that some species, such as Amazonian frogs, possess traits that allow them to use the matrix for movement and reproduction, as well as allowing them to tolerate edge effects and survive in the remaining fragments (Gascon et al., 1999).

Some species, such as frogs, possess traits that allow them to survive habitat fragmentation in rainforests. Source: Niem, 2015
Some species, such as frogs, possess traits that allow them to survive habitat fragmentation in rainforests. Source: Niem, 2015

LOOKING TO THE FUTURE…

Considering the range of impacts, it is unsurprising that the fragmentation of rainforests is one of the greatest threats to global biodiversity (Magnago et al., 2014). And the future does not look bright; as human populations continue to rise, the extent of deforestation and fragmentation of our forests is likely to also increase (Haddad, 2015).

But all is not lost; conservation projects mitigate some negative impacts, with studies discovering types of forest that can reduce edge effects near fragment margins (Mesquita et al., 1999).

BUT WHAT CAN I DO?

Take a look at the following website by Greenpeace and see what you can do to prevent deforestation: http://www.greenpeace.org/usa/forests/solutions-to-deforestation/

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References

Bierregaard, R., 2011. Forest fragments under research in the Biological Dynamics of Forest Fragments Project. [photograph] Reproduced in: Hance, J., 2011. Lessons from the world’s longest study of rainforest fragments. [online] Available at: https://news.mongabay.com/2011/08/lessons-from-the-worlds-longest-study-of-rainforest-fragments/ [Accessed: 21/03/17]

Gascon, C.; Lovejoy, T. E.; Bierregaard, R. O.; Malcolm, J. R.; Stouffer, P. C.; Vasconcelos, H. L.; Laurance, W. F.; Zimmerman, B.; Tocher, M. and Borges, S., 1999. Matrix habitat and species richness in tropical forest remnants. Biological Conservation, 91(2-3), pp. 223-229

Haddad, N. M.; Brudvig, L. A.; Clobert, J.; Davies, K. F.; Gonzalez, A.; Holt, R. D.; Lovejoy, T. E.; Sexton, J. O.; Austin, M. P.; Collins, C. D.; Cook, W. M.; Damschen, E. I.; Ewers, R. M.; Foster, B. L.; Jenkins, C. N.; King, A. J.; Laurance, W. F.; Levey, D. J.; Margules, C. R.; Melbourne, B. A.; Nicholls, A. O.; Orrock, J. L.; Song, D. and Townshend, J. R., 2015. Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science Advances, 1(2), pp. 1-9

Laurance, W.F.; Camargo, J. L. C.; Fearnside, P. M.; Lovejoy, T. E.; Williamson, G. B.; Mesquita, R.C.G.; Meyer, C. F. J.; Bobrowiec, P. E. D. and Laurance, S.G.W., 2016. An Amazonian forest and its fragments as a laboratory of global change. pp. 407-440. In: L. Nagy, B. Forsberg, P. Artaxo (eds.) Interactions Between Biosphere, Atmosphere and Human Land Use in the Amazon Basin. Springer (Ecological Studies 227), Berlin, Alemanha.

Magnago, L. F. S.; Edwards, D. P.; Edwards, F. A.; Magrach, A.; Martins, S. V. and Laurance, W. F., 2014. Functional attributes change but functional richness is unchanged after fragmentation of Brazilian Atlantic forests. Journal of Ecology, 102(2), pp. 475-85

Mesquito, R. C. G.; Delamônica, P. and Laurance, W. F., 1999. Effect of surrounding vegetation on edge-related tree mortality in Amazonian forest fragments. Biological Conservation, 91(2-3), pp. 129-134

Niem, Y. Tree frog silhouette. [photograph] Available at: http://fotovenopilon.si/entry/jury/awards.php?section=D [Accessed: 22/03/17]

Ribeiro, M. C.; Metzger, J. P.; Martensen, A. C.; Ponzoni, F. J. and Hirota, M. M., 2009. The Brazilian Atlantic Forest: How much is left, and how is the remaining forest distributed? Implications for conservation. Biological Conservation, 142(6), pp. 1141-1153

Roberts, G., 2016. Cassowary on road. [photograph] Available at: http://sunshinecoastbirds.blogspot.co.uk/2016/06/queensland-road-trip-13-etty-bay.html [Accessed: 22/03/17]

Turner, I. M., 1996. Species Loss in Fragments of Tropical Rain Forest: A Review of the Evidence. Journal of Applied Ecology, 33(2), pp. 200-209



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.

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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



A perfect invader for the perfect invasion

Posted on by Aaron Shakides

Elegant yet destructive, subtle yet menacing. The Lionfish colonization of the Caribbean was a perfect invasion. fishnew

Red Lionfish (Pterois volitans) are a beautiful, elegant fish, yet as the saying goes, “never judge a book by its cover”. Lionfish have invaded and colonized most parts of the Caribbean with the species spreading so fast that researchers and marine biologists are worried about the future of the Caribbean ecosystem.

 

What are invasive species?

Invasive species are known to cause extinctions of species and reduction in ecosystem biodiversity as they often outcompete other species in their newly invaded ecosystems². An invasive species is a species not originally from an ecosystem causing economic or environmental harm with potential harm to human health³. Invasive species are often unintended hitchhikers on cargo ships being carried around the world in ballast water and in shipped goods. Over the past few years, lionfish have become the poster child for invasive species in the Atlantic Ocean, receiving as much attention as zebra mussels and Asian carp⁴.

 

Why are lionfish in the Caribbean?

Native to the Pacific and Indian ocean, the red lionfish were first seen in the Caribbean in the late 1980s and now have spread all throughout the Caribbean as seen in the image below. These bewitchingly beautiful fish come armed with highly venomous spines, having very few natural predators, a perfect facilitator for a successful invasion. Lionfish continue to spread through the Caribbean (as seen in figure 2⁵) due to very fortunate characteristics of being very resilient to large temperature variations and biologically resistant to most diseases and parasites⁶.

maps

How are invasive species affecting ecosystems?

Coral reefs are amongst the most diverse ecosystems on earth with all parts of this ecosystem dependent on one another from life cycles of organisms to biological structure and function of organisms. Invasive species often disturb functioning habitats by eating juvenile fish⁹, reducing fish populations and disturbing the balances of reef ecosystems and essentially modifying the ecosystems¹⁰. This is what happened with the lionfish resulting in concern from researchers and marine biologists to the long-term future of the reefs with a change in the ecosystem structure and function.

 

Invasive species often can carry disease with them having massive effects on organisms living in the ecosystem. Organisms living within the ecosystem may be vulnerable to new disease, reducing the organisms chance of survival. An example of this is the Dutch Elm disease being introduced into America and Europe resulting in the rotting of tree roots and starving the tree of nutrition.

 

Why are lionfish damaging?

Lionfish feast upon juvenile fish and small crustaceans around coral reefs, with research identifying that a single lionfish residing on a patch of coral reef can reduce recruitment of juvenile fish by 79%, greatly reducing fish biodiversity⁴ ⁷. The lionfish’s’ prey is essential in reducing toxic algae that poison and suffocate the coral reefs, which without reduce the growth of corals⁴. The expansion of lionfish put additional stress on coral reefs already stressed by climate change, pollution, acidification, disease and overfishing⁸.

 

 

 

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References

 

1 – Clark, C., 2015. Lionfish study explores idea of eating an ecological problem. Available at: https://phys.org/news/2015-11-lionfish-explores-idea-ecological-problem.html. Last accessed on 12th March 2017.

 

2 – Clavero Pineda, M. and García-Berthou, E., 2005. Invasive species are a leading cause of animal extinctions. Trends in Ecology and Evolution.

 

3 – Mooney, H.A. and Hobbs, R.J. eds., 2000. Invasive species in a changing world (Vol. 23). Washington, DC: Island Press.

 

4 – NOAA., 2014. Invasive Lionfish Threaten Coral Reefs and Fisheries. NOAA Fisheries. Available at: http://www.nmfs.noaa.gov/stories/2014/12/12_01_14impacts_of_invasive_lionfish.html. Last accessed on 14th March 2017.

 

5 – USGS., 2017. Nonindigenous Aquatic Species. Available at: https://nas.er.usgs.gov/queries/SpeciesAnimatedMap.aspx?speciesID=963. Last accessed on 20th March 2017.

 

6 – Morris Jr, J.A. and Whitfield, P.E., 2009. Biology, ecology, control and management of the invasive Indo-Pacific lionfish: an updated integrated assessment.

 

7 – Albins, M.A. and Hixon, M.A., 2008. Invasive Indo-Pacific lionfish Pterois volitans reduce recruitment of Atlantic coral-reef fishes. Marine Ecology Progress Series, 367, pp.233-238.

 

8 – Goldberg, J. and Wilkinson, C., 2004. Global threats to coral reefs: coral bleaching, global climate change, disease, predator plagues and invasive species. Status of coral reefs of the world, 2004, pp.67-92.

 

9 – Guy, A., 2016. Facing a Plague of Invasive Lionfish, Caribbean and Gulf Communities Get Creative. Oceana. Available at: http://oceana.org/blog/facing-plague-invasive-lionfish-caribbean-and-gulf-communities-get-creative. Last accessed on 19th March 2017.

 

10 – Green, S.J., Akins, J.L., Maljković, A. and Côté, I.M., 2012. Invasive lionfish drive Atlantic coral reef fish declines. PloS one, 7(3).

 

 

 

 



Shedding light on urbanisation: how will our nocturnal species respond to artificial night lighting?

Posted on by Luke Vassor

Moving to Mars, floating cities and building upwards – all suggested solutions for our exploding human population, and with this population comes all of our infrastructure, including artificial lighting.

BUT while we remain on ground-level and on-land here on Earth, how will the species which exist in the dark respond to the one thing which keeps us moving at night, artificial lighting?

Earth's night lighting, as seen from space (source: NASA)
Earth’s night lighting, as seen from space (source: NASA)

 

Species which are active at night, nocturnal species, have evolved to exist at a time when others, like humans, don’t (until recently). However, since the invention of electric lighting 100 years ago, human beings have slowly transformed the global night time environment. This has not only led to a reduction in visible stars in the night sky, but has also had profound ecological effects on our nocturnal communities (Longcore and Rich, 2004).

The reason light can have such a profound impact lies in its use as a cue for nocturnal activities. All organisms have specific “rhythms” as a result of an internal “body clock” synchronising with daily cycles. This circadian rhythm relies on an internal light-controlled timer (Bradshaw and Holzapfel, 2010). Over 60% invertebrate and 30% vertebrate animals exhibit nocturnal rhythms, using the rising and setting of the sun as their cue to emerge from their day-time roosts or shelters (Hölker et al., 2010). Our human artificial lighting can confuse organisms in determining when it is day or night and interfere with these rhythms (Longcore et al., 2015).

Long-exposure photograph of insects attracted to a municipal street light
Long-exposure photograph of insects attracted to a municipal street light

However, it is actually much more complicated a picture than nocturnal organisms becoming disoriented by artificial lighting. This is due to a “trophic cascade” which is the knock-on effect along the food chain of an event occurring with one organism at one link in the chain. By disrupting the rhythm of one organism, the consequences can carry across the whole community. This is well documented in one of the most charismatic nocturnal animals, bats. In the UK, all bats use echolocation to navigate in the dark (Speakman, 1995). Among UK bats are fast- and slow-fliers, adapted to different environments. As many of the bat insect prey are attracted to street lights, the fast-fliers can fly underneath the lights to feed on the insects (Matthews et al., 2015). However, slow-fliers tend not to be seen doing this as they are not fast enough to escape predators, to whom they are exposed when beneath the light.

A bat foraging under a street light in Thailand (video screenshot)

This means that whilst it may be argued artificial lights have a positive effect on bats by concentrating their food, only fast-flying species can take advantage, passing through this new environmental filter imposed by artificial light. This may result in fast-fliers out-competing slow-fliers (Arlettaz et al., 2000). In this instance, only certain aerial insect species will survive the enhanced predation from fast-flying bats and move through this new “biotic” filter. As more and more artificial lighting continues to be installed, we may witness a change in the composition of certain nocturnal communities triggered by a shift in the functional traits within certain groups.

Word count: 496

References

Arlettaz, R. et al. (2000) Competition for food by expanding pipistrelle bat populations (Pipistrellus pipistrellus)      might contribute to the decline of lesser horseshoe bats (Rhinolophus hipposideros). Biological Conservation. 93(1),  pp. 55–60.

Bradshaw, W.E. and Holzapfel, C.M. (2010) What Season Is It Anyway? Circadian Tracking vs. Photoperiodic  Anticipation in Insects. Journal of Biological Rhythms. 25(3), pp. 155–165.

Hölker, F. et al. (2010) Light pollution as a biodiversity threat. Trends in Ecology and Evolution. 25(12), pp. 681–682.

Longcore, T. and Rich, C. (2004) Ecological light pollution. Frontiers in Ecology and the Environment. 2(4), pp. 191–  198.

Longcore, T. et al. (2015) Tuning the white light spectrum of light emitting diode lamps to reduce attraction of  nocturnal arthropods. Philosophical Transactions of the Royal Society B: Biological Sciences. 370(1667), 20140125

Mathews, F. et al. (2015) Barriers and benefits: implications of artificial night-lighting for the distribution of  common  bats in Britain and Ireland. Philosophical Transactions of the Royal Society B. Biological Sciences 370,  20140124.

Speakman, J.R. (1995) Chiropteran nocturnality. Symposium of the Zoological Society of London 67(67), pp. 187–  201.

 



Help! We’re Sinking: The Drowning Atoll Island Communities

Posted on by Kayra Salih
Figure 1. A typical atoll island, source: http://www.ventanasvoyage.com/images/coral%20atoll.jpg
Figure 1. A typical atoll island, source: http://www.ventanasvoyage.com/images/coral%20atoll.jpg

What is sea level rise (SLR)?

The term is pretty self-explanatory in the sense that sea level is rising globally; it has risen by ~3.1mm yr-1 since the 1990s (Goelzer et al., 2015). This is due to the complex interactions of many drivers under recent climate change (Figure 2). This SLR is having global consequences including the loss of low-lying land, of which atoll islands are of the most vulnerable and threatened (Nicholls et al., 2007).

Figure 2. Diagram illustrating the causes of SLR, source: https://deq.nc.gov/about/divisions/coastal-management/coastal-management-hot-topics/sea-level-rise
Figure 2. Diagram illustrating the causes of SLR, source: https://deq.nc.gov/about/divisions/coastal-management/coastal-management-hot-topics/sea-level-rise

Atoll Island Communities

Atolls are mid-ocean annular reefs surrounding a central lagoon (Figure 1) (Woodroffe, 2008). Atoll islands are notoriously vulnerable to the effects of SLR for three main reasons (see Figure 3 below) (Woodroffe, 2008):

Figure 3. The three main impacts of SLR on atoll islands.
Figure 3. The three main impacts of SLR on atoll islands.

Impacts on Humans

These environmental changes inevitably have impacts on the surrounding ecosystem; affecting the terrestrial, aquatic and marine communities, including human populations. The world is now experiencing a wave of ‘climate change refugees’ (Farbotko & Lazarus, 2012) who have been forced to seek asylum in other countries, for example the islanders of Tuvalu.

Tuvalu is a country in the South Pacific solely consisting of low-lying coral and atoll islands (Figure 4) (Farbotko & Lazrus, 2012). Residents have already been forced to evacuate their homes due to flooding, in addition to saltwater incursion rendering their groundwater drinking source unsuitable (Connell, 2016). Sea level around Tuvalu is currently rising by ~5.1mm yr-1 (Connell, 2016). This is a common tale throughout Earth’s atoll islands, and one which is likely to become more common in the future.

Figure 4. Map of Tuvalu showing its many atoll islands, source: http://www.nanumea.net/Photos%20page/Tuvalu%20Map%20with%20arrow%20and%20ack%20-%20from%20Smithsonian%20(a).jpg
Figure 4. Map of Tuvalu showing its many atoll islands, source: http://www.nanumea.net/Photos%20page/Tuvalu%20Map%20with%20arrow%20and%20ack%20-%20from %20Smithsonian%20(a).jpg

Effects on Marine Organisms

The marine ecosystem surrounding islands is also experiencing adverse and damaging impacts from sea level rise. For example, the health of coral reefs is already being degraded by warming oceans contributing to coral bleaching (Figure 5).

Figure 5. Infographic explaining coral bleaching and its causes, source: http://oceanservice.noaa.gov/facts/coralbleaching-large.jpg
Figure 5. Infographic explaining coral bleaching and its causes, source: http://oceanservice.noaa.gov/facts/coralbleaching-large.jpg

It can be argued that rising sea levels may in fact protect corals from overexposure to sunlight as they are deeper (Woodroffe & Webster, 2014). However, this will mostly mean that corals are too deep to allow their symbiotic algae to survive, which will ultimately lead to coral death (Woodroffe & Webster, 2014).

These impacts lead to wider community impacts on marine organisms; coral-dependent fish will either migrate or die (Andréfouët et al., 2015). The decline in fish stocks will also affect human populations which depend on this resource. Furthermore, the whole community will be affected by changes in food resources and suitable habitat, possibly leading to the collapse of the ecosystem (Andréfouët at al., 2015).

The future…

More areas are predicted to be underwater in the future according to SLR projections (Goelzer et al., 2015). This will not only have an impact on the animal populations dependent on fragile atoll ecosystems; but also on human populations- with an increasing number of environmental asylum seekers. The future will likely see increasing numbers of atoll island communities drowning!

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References

Andréfouët, S., Dutheil, C., Menkes, C.E., Bador, M. & Lengaigne, M. (2015). Mass mortality events in atoll lagoons: environmental control and increased future vulnerability. Global Change Biology. 21:195-205.

Connell, J. (2016). Last days in the Carteret Islands? Climate change, livelihoods and migration on coral atolls. Asia Pacific Viewpoint. 57:3-15.

Farbotko, C. & Lazrus, H. (2012). The first climate refugees? Contesting global narratives of climate change in Tuvalu. Global Environmental Change. 22:382-390.

Goelzer, H., Huybrechts, P., Loutre, M.F. & Fichefet, T. (2015). Future rates of sea-level rise from long-term coupled climate-ice sheet projections. In: EGU General Assembly Conference Abstracts. 17:15590.

Nicholls, R.J., Wong, P.P., Burkett, V.R., Codignotto, J.O., Hay, J.E., McLean, R.F., Ragoonaden, S. & Woodroffe, C.D. (2007). Coastal systems and low-lying areas. In: Parry, M.L., Canziani, O.F., Palutikof, J.P., van der Linden, P.J. & Hanson, C.E. (Eds.). Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press: UK. pp. 315-356.

Woodroffe, C.D. (2008). Reef-island topography and the vulnerability of atolls to sea-level rise. Global and Planetary Change. 62:77-96.

Woodroffe, C.D. & Webster, J.M. (2014). Coral reefs and sea-level change. Marine Geology. 352:248-267.



Climate Change IS happening, and it’s set to starve the planet… (The opposite of FAKE NEWS!)

Posted on by Anonymous

With the large scale funding cuts of the Environmental Protection Agency in the USA, the current rapid rates of climate change and CO2 release show no hope of stopping.

But seeing as though plants breathe using CO2 (through the process of photosynthesis), and use carbon in their growth, surely the increased amounts of CO2 being pumped into our atmosphere is a good thing for plants?  As studies have shown; perhaps not…

Plants require very specific environmental conditions to function efficiently, and any changes in these conditions can be detrimental.  Although it has been shown that increased CO2 initially causes an increase in the rate of photosynthesis and growth of leaves and roots (Taylor et al 1994), generally, in the long-term, the stimulation of photosynthesis is actually suppressed!

This is mainly due to negative effects on the plants function, such as the build-up of excess starch (sugars) in leaves via increased photosynthesis, hindering breathing of CO2 via pores; called the stomata (Makino & Mae 1999), and increased CO2 also causes the stomata to partially close (Singh 2009), resulting in an inability to respire efficiently (Ryan 1991).

The mechanism for respiration in a plant leaf, through the stomata.
The mechanism for gas exchange in a plant leaf, through the stomata.  Source: Understanding Evolution

The failure to respire efficiently can cause the death of many food crops globally that are vital to feeding our populations!

Increased environmental CO2 also results in global warming due to increased reflection of the Sun’s radiation back to the Earth’s surface; and a temperature increase of 2-3⁰C over the next 30-50 years (IPCC 2007) is predicted to cause problems for our crops.  For example, warmer temperatures affect plants mainly when they are developing, and this has been shown to reduce the numbers of our food crop plants by 80%-90% (Hatfield & Prueger 2015), having dire consequences for our food supplies!

The global change in surface temperature from 1901-2012. A worrying trend that is set to worsen... Source: National Snow & Ice Data Center
The global change in surface temperature from 1901-2012. A worrying trend that is set to worsen… Source: National Snow & Ice Data Center

Climate change is also set to increase the frequency of extreme weather events (Rosenzweig et al 2001). With increased storms and flooding drowning plants in some areas, and in other areas increased drought, resulting in a lack of water for plants to function with, which they rely heavily on for processes such as photosynthesis, vital for growth and survival.  The equation for photosynthesis is shown below, in case you have forgotten…

 

The equation for photosynthesis, showing how carbon dioxide and water are transformed into oxygen and sugars through the light energy from the sun hitting the chlorophyll pigments in the plants cells.
The equation for photosynthesis, showing how carbon dioxide and water are transformed into oxygen and sugars through the light energy from the sun interacting with the chlorophyll pigments in the plants cells.

 

With increasing global temperatures, drought affected areas will increase from 15.4% to 44.0% by 2100 (Li et al 2009) – resulting in less land to grow crops, which will be disastrous for our food security, along with the fact that the number of suitable growing days per year for our crops will decrease by 11% by the year 2100 (Mora et al 2015)!

A sunny day on a Californian beach? Not exactly… This is Californian farmland suffering from a severe drought – completely unusable!
A sunny day on a Californian beach? Not exactly… This is Californian farmland suffering from a severe drought – completely unusable! Source:  New York Times

 

With the saying “Feed the World” becoming more and more poignant, our future looks bleak, as we are set to have less food security per person than ever before due to the detrimental effects that climate change will have on plant function. Also, plants not only provide food, but are also at the heart of our medicines and resources! So maybe Donald Trump ought to reconsider his views on climate change before threatening his new healthcare system before it has begun.

Word Count: 500

 

References:

Hatfield, J. and Prueger, J. (2015). Temperature extremes: Effect on plant growth and development. Weather and Climate Extremes, 10, pp.4-10.

IPCC, (2007). Climate Change 2007: Impacts, Adaptation and Vulnerability. New York: Cambridge University Press, p.17.

Li, Y., Ye, W., Wang, M. and Yan, X. (2009). Climate change and drought: a risk assessment of crop-yield impacts. Climate Research, 39, pp.31-46.

Makino, A. and Mae, T. (1999). Photosynthesis and Plant Growth at Elevated Levels of CO2. Plant and Cell Physiology, 40(10), pp.999-1006.

Mora, C., Caldwell, I., Caldwell, J., Fisher, M., Genco, B. and Running, S. (2015). Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability. PLOS Biology, 13(6), p.e1002167.

Rosenzweig, C., Iglesius, A., Yang, X., Epstein, P. and Chivian, E. (2001). Climate change and extreme weather events – Implications for food production, plant diseases, and pests. Global Change & Human Health, 2(2), pp.90-104.

Ryan, M. (1991). Effects of Climate Change on Plant Respiration. Ecological Applications, 1(2), pp.157-167.

Singh, S. (2009). Climate change and crops. 1st ed. Berlin: Springer, pp.5-6.

Taylor, G., Ranasinghe, S., Bosac, C., Gardner, S.D.L. and Ferris, R. (1994). Elevated CO2 and plant growth: cellular mechanisms and responses of whole plants. Journal of Experimental Botany, 45, pp.1761-1774.



Too Close To Home – The Effect Of Urbanisation on Global Wildlife

Posted on by Alexis Alders
Urban fox
Hobson (2015)

 

With increasing urbanisation of once wild landscapes, nature is forced to live right on our doorstep. With reports of vicious seagulls, giant rats, and foxes attacking babies, how is wildlife coping with living in the city?

 

Cities currently comprise around 3% of land globally (Faeth et al., 2011) and as this increases, more research is focusing on the animals we share our cities with. Urban development causes habitat fragmentation, enables the invasion of non-native species, and changes regional climates, which leads to a loss of wildlife. But what effect does the change in the environment have on the remaining flora and fauna?

 

In Mexico City, the number of bird species has decreased, but the number of birds overall has increased (Ortega-Alvarez and MacGregor-Fors, 2009). This was also found in butterflies in Mexico (Ramirez-Restrepo et al. 2015). Another pattern found in cities is a decrease in the number of species in more developed areas (Faeth et al. 2011). Decreases in the number of species towards the city centre is due to the avoidance of increased pollution, noise and light in these areas (Ortega-Alvarez and MacGregor-Fors, 2009). Artificial lighting affects the behaviour of bats (Hale et al 2015) and many species are sensitive to high human disturbance (Ortega-Alvarez and MacGregor-Fors, 2009). Few species can survive in cities, as they are inhospitable environments. Known as generalists, these species can eat food from more than one source and can survive in several habitats. Food is more available in the form of human rubbish (Ortega-Alvarez and MacGregor-Fors, 2009) which supports a larger abundance of animals. However, this increase in numbers is only seen in generalists, which can make use of this resource.

 

Which species can survive in a city is determined by hierarchical theoretical filters based on the environment (Aronson et al., 2016). A diagram of this can be seen below.

Urban hierarchical filters
Fig. 1 (Aronson et al., 2016, pg. 2954)

 

Generalists are more likely to meet these criteria due to flexibility within their characteristics. The structure of cities greatly impacts the species that live within them (Aronson et al. 2016). Management intensity in gardens is the main factor affecting spider communities, while bird communities are significantly affected by the abundance of woody plants (Sattler et al. 2010). Butterfly communities are structured by distance to city centre, and distance to well-preserved habitat both of which are linked to the overall structure of the city (Ramirez-Restrepo et al. 2015), as shown below:

City structure mosaic
Fig 1. (Nilon, 2011, pg.47)

So cities have massive effects on communities of wildlife. Therefore, is it inevitable that there will be human-wildlife conflicts? Not necessarily – urban wildlife can teach children living in urban environments about the natural world (Faeth et al., 2011). Additionally, increased biodiversity is linked to sustainable development and a reduction in poverty (Nilon, 2011). So although urban wildlife may be viewed as savage scroungers surviving at the fringes of our society, they actually represent a valuable resource.

 

References

Aronson, M.F., Nilon, C.H., Lepczyk, C.A., Parker, T.S., Warren, P.S., Cilliers, S.S., Goddard, M.A., Hahs, A.K., Herzog, C., Katti, M. and La Sorte, F.A., (2016) Hierarchical filters determine community assembly of urban species pools. Ecology, 97(11), pp.2952-2963.

Faeth, S.H., Bang, C. and Saari, S., (2011) Urban biodiversity: patterns and mechanisms. Annals of the New York Academy of Sciences, 1223(1), pp.69-81.

Hobson, S. (2015) How to photograph urban wildlife, available from: http://www.discoverwildlife.com/wildlife-nature-photography/how-photograph-urban-wildlife [accessed: 15/03/17]

Nilon, C.H., (2011) Urban biodiversity and the importance of management and conservation. Landscape and ecological engineering, 7(1), pp.45-52.

Ortega-Álvarez, R. and MacGregor-Fors, I., (2009) Living in the big city: Effects of urban land-use on bird community structure, diversity, and composition. Landscape and Urban Planning, 90(3), pp.189-195.

Ramírez-Restrepo, L., Cultid-Medina, C.A. and MacGregor-Fors, I., (2015) How many butterflies are there in a city of circa half a million people?. Sustainability, 7(7), pp.8587-8597.

Sattler, T., Borcard, D., Arlettaz, R., Bontadina, F., Legendre, P., Obrist, M.K. and Moretti, M., (2010) Spider, bee, and bird communities in cities are shaped by environmental control and high stochasticity. Ecology, 91(11), pp.3343-3353.

 

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Honey, I can’t bee-lieve what I’m seeing!

Posted on by Luke Donovan
Why does it keep getting hotter ... and where has my home gone?!
Why does it keep getting hotter … and where has my home gone?!

Enjoying that tangerine? That glass of cranberry juice this morning? Waking up in those 100% cotton bed sheets? Well, you can thank the bees. They are the major pollinators of plants and crops in ecosystems and are invaluable to us (Brown and Paxton, 2009; Costanza et al., 1997). Unfortunately, bees are declining, mainly through human causes (boo!). Habitat loss, fragmentation, invasive species and climate change are all factors that are harming the bee populations.

Homes under the hammer – no, not the TV show

The human population is set to reach ~9 billion by 2050 (United Nations, 2004), seeing an increase in resources to feed all these mouths. Habitats need to be converted into farmland to provide crops (which ironically will be pollinated by bees!). It is known that human disturbance can negatively impact bee numbers (Winfree et al., 2009). It could also cause populations to inbreed, meaning they are susceptible to nasty diseases causing death (Brown and Paxton, 2009). The more we harm bee habitats, we are causing detriment to their numbers and are also causing a negative effect on our lives – how counterproductive.

More food and less destruction! (pintrest.com)
More food and less destruction!

How did you get here?!

Sometimes you get an unfamiliar, ugly head pop up in a population which is causing harm to the original species that live there – otherwise known as an invasive species. The process is usually:

  • Introduction
  • Colonisation
  • Naturalisation
  • Spread
  • Impact

 

This can be seen in the Africanized honeybee in South America, largely replacing the European honeybee by outcompeting it (Schweiger et al., 2009).

Left: Africanized Honey bee - Right: European Honey Bee
Left: Africanized Honey bee – Right: European Honey Bee.

Nature has no air-conditioning: Get used to the warm!

Despite belief from certain world leaders, climate change is happening. Climate change brings many problems to bee populations, such as a change in the relationship between plants and the bees and an increase in disease and parasites (Le Conte and Navajas, 2008).

In snowy environments, climate change is causing snow to melt earlier, meaning flowers are emerging earlier, causing bees to be out of sync (phenology), thus causing changes in what’s called their ‘functional traits’ which are traits that typically relate to changes in the environment.

Bees must build up sufficient honey stores so that they can survive over the winter periods, however climate change is causing a change in flower development (and pollen production) whereby drought is responsible for the decline in flower numbers (La Conte and Navajas, 2008). This means that the bees cannot build the right amount of honey stores and starve over the winter period.

The future of the bees

There are conservation efforts to try and help bees (woo!) such as (Brown and Paxton, 2009):

  • Minimising habitat loss
  • Making agricultural habitats bee-friendly
  • Training scientists and the public

 

If bees were to go extinct tomorrow, we would have to self-pollinate EVERYTHING, as bees do all this hard work for us, for nothing. If we lose bees, we lose the planet, we must ensure bees do not leave us otherwise the future will look very bleak (with no hint of yellow and black).

Thanks for reading, lets hope we see these guys buzzing around for a long time
Thanks for reading, lets hope we see these guys buzzing around for a long time.

[498 words]

References

Brown, M. and Paxton, R. (2009). The conservation of bees: a global perspective. Apidologie, 40(3), pp.410-416.

Costanza, R., d’Arge, R., de Groot, R., Farber, S., Grasso, M., Hannon, B., Limburg, K., Naeem, S., O’Neill, R., Paruelo, J., Raskin, R., Sutton, P. and van den Belt, M. (1997). The value of the world’s ecosystem services and natural capital. Nature, 387, pp.253-260.

Le Conte, Y. and Navajas, M. (2008). Climate change: impact on honey bee populations and diseases. Rev. sci. tech. Of. int. Epiz, 27(2), pp.499-510.

Schweiger, O., Biesmeijer, J., Bommarco, R., Hickler, T., Hulme, P., Klotz, S., Kühn, I., Moora, M., Nielsen, A., Ohlemüller, R., Petanidou, T., Potts, S., Pyšek, P., Stout, J., Sykes, M., Tscheulin, T., Vilà, M., Walther, G., Westphal, C., Winter, M., Zobel, M. and Settele, J. (2010). Multiple stressors on biotic interactions: how climate change and alien species interact to affect pollination. Biological Reviews, 85, pp.777-795.

United Nations (2004) World Population to 2300, New York. [online] http://www.un.org/esa/population/ publications/longrange2/WorldPop2300final.pdf

Winfree, R., Aguilar, R., Vázquez, D., LeBuhn, G. and Aizen, M. (2009). A meta-analysis of bees’ responses to anthropogenic disturbance. Ecology, 90(8), pp.2068-2076.



Trophic cascades as effects of environmental change on food webs.

Posted on by Rupert Powell

Environmental change is affecting communities and ecosystems in a number of different ways. One of the effects it is having is on food webs. A food web is a collection of both interconnected and independent food chains which represent all predator prey relationships in an ecosystem or community as well as the primary producers at the bottom.

There are two main ways in which environmental change can affect food webs. The effect could be top down, where environmental change affects the number of predators at the top of the food web and such change brings about a change in the number of organisms lower in the food web. This change can have disastrous effects on the ecosystem. Conversely the effect could be bottom up, where environmental change has affected the number of primary producers, organisms such as grass, which form the foundation of the food web; this would in turn affect organisms higher in the food web. This again could have severe negative effects on the ecosystem or community. The effect that is caused by the change of abundance of either the top predators or primary producers is known as a trophic cascade.

 

Figure 1 illustrates an example of a potential trophic cascade which could be caused by environmental change where there is a reduction of the average individual body mass of the top predator, the shore crab Carcinus maenas, in this marine ecosystem. Reduction in body mass is a common response to climate change (Gardner et al. 2011). The reduction in the body mass of the crabs increased the biomass, the total weight of organisms in an ecosystem or community, of the community. The reduction in body mass of the shore crab increased the number, and consequently the biomass, of the intermediate fish predators that the shore crab feeds upon. The increased abundance of fishes reduced the numbers of the algae eating organisms. The fall in the number of algae eating organisms obviously led to an increase in algae, this increase could lead to algal blooms which can be devastating to ecosystems. (Jochum et al. 2012).

Figure 1. Scatterplot of (a) Carcinus maenas biomass, (b) Perciformes biomass, (c) log10 number of micro-grazers and (d) chlorophyll concentration of microalgal biofilm against Carcinus maenas body mass MC′ (Jochum et al. 2012).
Figure 1. Scatterplot of (a) Carcinus maenas biomass, (b) Perciformes biomass, (c) log10 number of micro-grazers and (d) chlorophyll concentration of microalgal biofilm against Carcinus maenas body mass MC′ (Jochum et al. 2012).
Figure 2. Balearic shearwaters in flight (Martinez)
Figure 2. Balearic shearwaters in flight (Martinez)

An example of an actual trophic cascade, which is illustrated in figure 3, is the effect of sea temperature on the Balearic shearwater, Puffinus mauretanicus (Figure 2). As sea temperatures rose in the late 1990s the bird’s range spread northwards (Wynn et al. 2007) resulting in an increase in its population numbers. A concentration of the population further north resulted in an increased occurrence of anchovies and sardines, both prey of the Balearic shearwater, in the Bay of Biscay. The increased occurrence of anchovies and sardines resulted in a decrease in calanoids, calanoids make up a significant proportion of plankton (Blaxter et al. 1998) and so are an important food source in the ecosystem. (Luczak et al. 2011)

Figure 3. Scatterplot of the number of individuals of Balearic shearwater against (a) sea surface temperature, (b) the plankton index), (c) sardine and (d) anchovy (Luczak et al. 2011).
Figure 3. Scatterplot of the number of individuals of Balearic shearwater against (a) sea surface temperature, (b) the plankton index), (c) sardine and (d) anchovy (Luczak et al. 2011).

Trophic cascades can be disastrous as they can result in the total collapse of ecosystems and are an often overlooked result of environmental change and the effect it can have on ecosystems or communities.

 

References:

Blaxter, J. H., Douglas, B., Tyler, P. A., & Mauchline, J. (1998). The biology of calanoid copepods (Vol. 33). Academic Press.

Gardner, J.L., Peters, A., Kearney, M.R., Joseph, L. and Heinsohn, R., 2011. Declining body size: a third universal response to warming?. Trends in ecology & evolution, 26(6), pp.285-291.

Jochum, M., Schneider, F.D., Crowe, T.P., Brose, U. and O’Gorman, E.J., 2012. Climate-induced changes in bottom-up and top-down processes independently alter a marine ecosystem. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 367(1605), pp.2962-2970.

Luczak, C., Beaugrand, G., Jaffre, M. and Lenoir, S., 2011. Climate change impact on Balearic shearwater through a trophic cascade. Biology Letters, 7(5), pp.702-705.

Martinez X. Balearic shearwaters in flight. Accessed 16 March 2017 <http://www.arkive.org/balearic-shearwater/puffinus-mauretanicus/image-G75476.html#src=portletV3>

Wynn, R.B., Josey, S.A., Martin, A.P., Johns, D.G. and Yésou, P., 2007. Climate-driven range expansion of a critically endangered top predator in northeast Atlantic waters. Biology Letters, 3(5), pp.529-532.

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