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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).

 

 

 

 



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.



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.

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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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Nasty Neonicotinoids: The cause of declines in Birds, Bees and Butterflies

Posted on by Imogen Ryan

 

As agriculture has intensified over the last century we have seen falling food prices and bigger fruit and veg, but what is the cost to our wildlife?

The increase in size of modern arable fields provides a veritable feast for many pests, destroying large areas of crop and literally eating into farmer’s profits. This has led to a rise in the use of pesticides to control these pests. However, not all the animals that are negatively affected by pesticides are harmful to crops, in fact some are beneficial.

Neonicotinoids

In the 1990’s a group of insecticides called neonicotinoids were developed which could be added to seeds before planting rather than externally sprayed onto the plants. The plant incorporates the chemical into all its tissues, giving insect pests a fatal dose upon taking a bite (Gilburn, 2015). This is good news for those beneficial animals that don’t munch their way through the crop right?

Wrong! The chemical gets into every part of the plant including the pollen and nectar (Blacquire et al 2012) which bees and butterflies feed on while pollinating plants. Farmland birds also often eat the seeds before they sprout. These animals don’t even have to be in the field to be affected as the majority of the chemical is not taken up by the plant and is leached into the soil water (Hallman et al 2014) and transported to wildflower field margins and neighbouring land.

What are the effects? 

Butterflies

The populations of widespread butterflies on monitored UK farmland sites have declined by 58% between 2000 and 2009 (Brereton et al 2011). This is negatively correlated with the increase in the use of neonicotinoids (Gilburn, 2015). Although it has not been proved to be a cause and effect relationship, the sudden decline in butterflies has not been seen in Scotland (Brereton et al 2011) where less neonicotinoids are used (Defra, 2014).

Painted Lady Butterfly -Alamy

Bees

Neonicotinoids are also threatening bees, impairing their homing ability and learning as well as their immunity to viruses. The chemical also reduces the growth of the colony and the production of queens (Cresswell, 2011). A recent field study by Rundolf et al (2015) has shown that the density of wild bees, nesting of solitary bees and growth of bumblebee colonies have all been reduced by neonicotinoid treated rape seeds.

neonicotinoid-pesticides-their-effect-on-bee-colonies-the-facts

Out for the count. Julia Garvin

 

Birds

A decline in insectivorous farmland birds, correlated with neonicotinoid use, has also been seen in the Netherlands (Hallman et al 2014). This is thought to be due to directly consuming the poisonous seeds (Goulson, 2013) or through the reduction in their insect food source.

Grey Partridge-Cambridge Bird Club

 

Do we need neonicotinoids anyway?

The use of neonicotinoids also appears to have no benefits to agricultural yields of soybean (Myers, 2014), Sunflower and Maize crops (Susuki, 2014). Methods like Integrated Pest Management can reduce the number of pests without the powerful chemicals so isn’t it time we put nature before ease?

More information on the effect on bees

References  painted-lady 

Blacquiere T, Smagghe G, Van Gestel CAM, Mommaerts V. 2012. ` Neonicotinoids in bees: a review on concentrations, side-effects and risk assessment. Ecotoxicology 21:973–992

Brereton TM, Roy DB, Middlebrook I, Botham M, Warren M. 2011. The development of butterfly indicators in the United Kingdom and assessments in 2010. Journal of Insect Conservation 15:139–151

Cresswell JE. 2011. A meta-analysis of experiments testing the effects of a neonicotinoid insecticide (imidacloprid) on honey bees. Ecotoxicology 20:149–157

Defra. 2014. Pesticide usage statistics. Available at https://secure.fera.defra.gov.uk/pusstats/ (accessed March 2017).

Gilburn, A.S., Bunnefeld, N., Wilson, J.M., Botham, M.S., Brereton, T.M., Fox, R., and Goulson, D. (2015). Are neonicotinoid insecticides driving declines of widespread butterflies? PeerJ:e1402

Goulson, D. (2013). An overview of the environmental risk posed by neonicotinoid insecticides. J. Appl. Ecol. 50, 977-987

Hallmann CA, Foppen RPB, Van Turnhout CAM, De Kroon H, Jongejans E. 2014. Declines in insectivorous birds are associated with high neonicotinoid concentrations. Nature 511:341–343

Myers, C., Hill, E. (2014). Benefits of Neonicotinoid Seed Treatments to Soybean Production. US Environmental protection agency

Rundlof M, Andersson GKS, Bommarco R, Fries I, Hederstrom V, Jonsson O, Klatt BK, ¨ Pedersen TR, Yourstone J, Smith HG. 2015. Seed coating with a neonicotinoid insecticide negatively affects wild bees. Nature 521:77–80

Susuki, D. (2014). More Bad News for Bees. Available at http://www.ecology.com/2014/10/31/the-new-word-for-bees/ (accessed March 2017)

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The Great Barrier Reef – Not so Great Anymore

Posted on by Edward Simmons

The great barrier reef is a place that the vast majority of people have heard of, perhaps due to its incredible natural beauty, or maybe due

Figure 1: An image of the great barrier reef we’re all familiar with; full of colour and life. Source: Cruiseexperts.com
Figure 1: An image of the great barrier reef we’re all familiar with; full of colour and life.
Source: Cruiseexperts.com

to the large host of species that it supports. Around 150 soft corals, 411 hard corals, 1625 bony fish, and about 1300 crustacean species call the great barrier reef their home, to name a few (Great barrier reef marine park authority, 2014). However, climate change is impacting the corals that make up the structure of the reef, with an estimated yearly loss of around 3,168km2 per year being the calculated loss between 1997 and 2003 alone (Bruno and Selig, 2007).

 

 

 

 

What are the Impacts of Climate Change?

 

Figure 2: Sea surface temperature anomalies for the Coral Sea, 1900-2013, using 1961-1990 average as a baseline. Source: Great barrier reef marine park authority, 2014
Figure 2: Sea surface temperature anomalies for the Coral Sea, 1900-2013, using 1961-1990 average as a baseline. Source: Great barrier reef marine park authority, 2014

Climate change has caused the sea surface temperatures to rise in recent years, as shown by figure 2 for the Coral Sea. In fact, the past 15 years has shown the hottest temperature averages all together, and this has many impacts on the animals and plants that live within the sea. This temperature rise leads to a phenomenon called coral bleaching. This is where corals lose their symbiotic algae, which live within the coral and provide it energy, which can lead to the coral’s death if the bleaching is prolonged or severe. The effects of this are easily seen, as the corals lose their colour, leaving just the white of the calcium skeleton (Brown, 1997).

As the temperature of the water increases, so does its ability to absorb CO2, leading to ocean acidification. The current level of atmospheric CO2 has been measured at 406.42 ppm, (NOAA, 2017), which is more than 100ppm above the maximum values seen over the last 740,000 years (Hoegh-Guldberg et al. 2007). 25% of the CO2 created by humans goes into the sea, leading to significant acidification. As the water turns more acidic, corals are unable to create their calcium skeletons as well, decreasing the rate at which they grow. The growth of corals has in fact decreased by 13.3% since 1990 (De’ath et al. 2009).

Climate change may lead to indirect damages to coral reefs too, with it leading to an increase in both the number and the intensity of storms, including hurricanes, in some regions (Hughes et al. 2003). This damages the corals, and the increase in frequency of the storms gives the reef less time to recover, killing some corals completely.

 

 

 

More than just the corals

Figure 3: Drained of colour, a contrast between a reef before and after bleaching. Source: dw.com
Figure 3: Drained of colour, a contrast between a reef before and after bleaching. Source: dw.com

The health of the corals also effect the many animals that inhabit the reef. The worst affected are the fish that require live corals as their homes, but fish that don’t depend on live coral are impacted too, as they are still dependent on the complexity of structure that the live coral bring (Pratchett et al. 2008).

With climate change growing more intense year by year, up to 60% reefs may be lost by 2030, and with them all the life which calls the reef home (Hughes et al, 2003).  So, while it certainly remains a barrier reef, perhaps it’s not so great anymore…

 

 

[Words: 500]

 

References

 

  • Brown B.E. 1997. ‘Coral bleaching: causes and consequences’ Coral reefs, 16, pp. 129-138
  • Bruno J.F. and Selig E.R. 2007. ‘Regional Decline of Coral Cover in the Indo-Pacific: Timing, Extent, and Subregional Comparisons’ PLoS one 2(8), e711
  • De’ath G., Lough J.M., Fabricus K.E. 2009. ‘Declining Coral Calcification on the Great Barrier Reef’ Science, 323, pp. 116-119
  • Great Barrier Reef Marine Park Authority 2014, Great Barrier Reef Outlook Report 2014, GBRMPA, Townsville.
  • Hoegh-Guldberg O. et al. 2007. ‘Coral Reefs Under Rapid Climate Change and Ocean Acidification’ Science, 318, pp. 1737-1742
  • Hughes T.P. et al. 2003. ‘Climate Change, Human Impacts, and the Resilience of Coral Reefs’ Science, 301, pp. 929-933
  • National Oceanic and Atmospheric Administration (NOAA), 2017. Trends in Atmospheric Carbon Dioxide. [Online] Available at: https://www.esrl.noaa.gov/gmd/ccgg/trends/index.html [Accessed: 21/03/2017]
  • Pratchett M.S. et al. 2008. ‘Effects of climate-induced coral bleaching on coral-reed fishes – ecological and economic consequences. Oceanography and marine biology: an annual review, 46, pp. 251-296


Global Warming: It’s Getting Hot In Here

Posted on by Rosie Chubbock

Warmer summer days, heat waves and mild winters- global warming must be a blessing in disguise, right? Wrong. A global temperature increase of only a few degrees could spell disaster for ecosystems and communities across the world.

warming-map-jpg
Temperatures changes across the globe between 1951 and 2005. (Hansen et al, 2006)

Global warming may be a controversial topic, but the bottom line is the planet IS getting warmer: an average of 0.8oC warmer over the past 40 years to be precise (Hansen et al, 2006). But who’s responsible? Unfortunately it seems we’re the culprits, with increasing carbon emissions from human activity blamed for recent temperature rise. Ice melt and sea level rise are both well-known consequences of global warming, but it’s also causing countless other impacts on species around the globe, from changes in migration and distribution to extinction (Hansen et al, 2006).

Polar ecosystems are perhaps the most vulnerable to warming: Arctic sea ice is disappearing at an alarming rate. For seals and walruses this means a loss of breeding and pupping grounds (Stroeve et al, 2008), causing population declines.

sea-ice
Change in Arctic sea ice over time: over 2 million square kilometers of sea ice has been lost in the past 40 years. (Post et al, 2013 & Perovich and Richter-Menge, 2009)

But the bad news doesn’t end there: sea ice is becoming less accessible and more fragmented, resulting in declining abundance and body condition of polar bears as they struggle to hunt seals (Post et al, 2013). The extreme food shortage has caused our beloved polar bear to start showing rather sinister behaviour: polar bear cannibalism is on the rise. The hunters have become the hunted with mothers eating their cubs and males attacking smaller females (Galligan et al, 2016).

Polar bears: iconic and lovable animals or viscous cannibals?
Polar bears: iconic and lovable animals or vicious cannibals? (Galligan et al, 2016)
Accessing sea ice hunting grounds is becoming more and more challenging for polar bears (Dell'Amore, 2014)
Accessing sea ice hunting grounds is becoming more and more challenging for polar bears as Arctic temperatures increase. (Dell’Amore, 2014)

Surprisingly, the most significant impact of decreasing sea ice in the Arctic ecosystem could be declining algae abundance. Despite its small size, ice algae is absolutely fundamental to the Arctic food web and cannot grow without the presence of sea ice (EPA, 2016).

The complex Arctic food web, displaying how a loss of sea ice can eventually have consequences for the largest mammals in the ecosystem (EPA, 2016).
The complex Arctic food web, displaying how a loss of sea ice can lead to a significant decrease in algae, which can eventually have consequences for even the largest mammals in the ecosystem (EPA, 2016).

Global warming impacts are not confined to the poles: numerous communities are experiencing distribution and migration changes. Multiple alpine plant communities have displayed an average upward shift in elevation of 29 meters per decade as they seek cooler temperatures (Lenoir et al, 2008). This consequently affects the distribution of other species within the ecosystem which rely on the plants for food and shelter.

Warming temperatures mean migratory bird communities in the US are returning up to 13 days earlier than a century ago, and numerous butterfly species in California are arriving earlier than previous years (EPA, 2016). Indirectly, changes in migration can impact other species within the ecosystem: e.g., an earlier increase in food availability for species such as birds which prey on these butterflies.

However some communities are not able to cope with warming, resulting in irreversible consequences. Amphibians are particularly vulnerable to warm/dry conditions, and suggestions have been made that abnormally high temperatures in 1987 caused by global warming were to blame for the extinction of the golden toad (Pounds and Crump, 1994). This isn’t a one off event: warm ocean temperatures in 1988 resulted in the disappearance of the orange-spotted filefish from Japanese waters (Dell’Amore, 2014), and extinctions are only expected to increase as temperatures continue to rise.

The Golden Toad: the first species extinction to be blamed on global warming triggered by human activity. The first of many? (Pounds and Crump, 1994 & Extinct Animals, 2016)
The Golden Toad: endemic to Costa Rica, and the first species extinction to be blamed on global warming triggered by human activity. But is it the first of many? (Pounds and Crump, 1994 & Extinct Animals, 2016)

[500 Words]

References

Dell’Amore, C. (2014) 7 Species Hit Hard by Climate Change- Including One That’s Already Extinct. Available at: http://news.nationalgeographic.com/news/2014/03/140331-global-warming-climate-change-ipcc-animals-science-environment/ [Accessed 10 March 2017]

EPA (2016) Climate Impacts on Ecosystems. Available at: https://www.epa.gov/climate-impacts/climate-impacts-ecosystems [Accessed 2 March 2017]

Extinct Animals (2015) Golden Toad. Available at: http://www.extinctanimals.org/golden-toad.htm [Accessed 12 March 2017]

Galligan, J., Smith, O., and Tran, K. (2016) Does Climate Change Pose a Significant Threat to Polar Bears? Available at: https://blogs.umass.edu/natsci397a-eross/does-climate-change-pose-a-significant-threat-to-polar-bears/ [Accessed 9 March 2017]

Hansen, J., Sato, M., Ruedy, R., Lo, K., Lea, D. W. and Medina-Elizade, M. (2006) Global temperature change. Proc natl Acad Sci USA. 103 (39) pp. 14288-14293

Lenoir, J., Gegout, J. C., Marquet, P. A., Ruffray, P., and Brisse, H. (2008) A significant upward shift in plant species optimum elevation during the 20th century. Science. 320 (5884) pp. 1768-1771

Perovich, D. K., and Richter-Menge, J. A. (2009) Loss of sea ice in the Arctic. Annual Review of Marine Science. 1 pp. 417-441

Post, E., Bhatt, U. S., Bitz, C. M., Brodie, J. F., Fulton, T. L., Hebblewhite, M., Kerby, J., Kutz, S. J., Stirling, I., and Walker, D. A. (2013) Ecological consequences of sea-ice decline. Science. 341 (6145) pp. 519-524

Pounds, J. A., and Crump, M. L. (1994) Amphibian declines and climate disturbance: the case of the golden toad and the harlequin frog. Conservation Biology. 8 pp. 72-85

Stroeve, J., Serreze, M., Drobot, S., Gearheard, S., Holland, M., Maslanik, J., Meier, W., and Scambos, T. (2008) Arctic sea ice extent plummets in 2007. Eos. 89 (2) pp. 13-14

 



From Sex to Starvation: Impacts of Decreasing Sea Ice on Arctic Communities

Posted on by James McWhirter

When you hear the word climate change, your mind immediately envisions a lonely polar bear swimming through a vast ocean looking for some lost ice on which to rest. If only it could be said that this was simply a dramatisation envisioned by climate change extremists in order to scare us into reducing our greenhouse emissions. If only…

Despite their constant denial, Fox News' can't say global warming isn't affecting their viewer ratings... (Mike Luckovich, 2015)
Despite their constant denial, Fox News’ can’t say global warming isn’t affecting their viewer ratings… (Image: Mike Luckovich, 2015)

Since the 1970’s, Arctic sea ice has decreased at a rate of 13.3% per decade, translating to loss of 13,500 square miles of sea ice coverage annually (Comiso et al., 2008). This drastic loss in sea ice coverage is having severely negative impacts on arctic animals that rely upon it for survival.

Sea ice extent (1970 - 2007) and projected decrease (2030 - 2100). (NOAA GFDL Model, n.d.)
Sea ice extent (1970 – 2007) and projected decrease (2030 – 2100). (Image: NOAA GFDL Model, n.d.)

Polar Bears:

Sea ice loss can be regarded as the main driver responsible for the 22% decrease in polar populations since 1987 (Derocher, 2004). Not only is the sea ice that is so necessary for them to hunt on disappearing, but their penile bones are fracturing during their most intimate moments.

While the function of a penis bone is still unknown (Simmons and Firman, 2013), many animals have them and it seems that chemical pollutants called PCBs may be having detrimental effects on the genitalia of polar bears.  It is suggested that PCBs cause (Sonne et al., 2006; Sonne et al., 2015):

  • Smaller testes
  • Smaller penis bones
  • Lower calcium density in penis bones making them weaker

 

The loss of sea ice has accelerated the incidence of penile fracture as lowered foraging ability has led to skinnier bears, and therefore higher levels of circulating pollutants due to nutritional stress (Sonne et al., 2015).

Reduced reproductive success will have a severe impact on future populations.

“If it breaks, you probably won’t have a bear that can copulate” – Christian Sonne, 2015

PCBeware!! (Image: Paul Nicklen/NGS)
PCBeware!! (Image: Paul Nicklen/NGS)

Walruses:

Walruses are being forced to utilise sea ice in areas of greater depth where there is no food, or move onto solid land (Greenpeace, 2012). Thousands of deaths in beaching populations have been reported due to overcrowding and panic stampedes into the water (Chadwick and Fischbaik, 2008), which are particularly dangerous to young pups. A number of abandoned calves have been observed swimming in water with depths of 3000m, as mothers are forced to deeper waters due to lack of food at overcroweded beaches (Cooper et al, 2006).

Retreating sea ice is driving thousands of Walruses towards land causing major overcrowding. There are an estimated 35,000 walruses on this beach (Photo: Corey Arrardo / NOAA/NMFS/AFSC/NMML)
Retreating sea ice is driving thousands of Walruses towards land causing major overcrowding. There are an estimated 35,000 walruses on this beach (Photo: Corey Arrardo / NOAA/NMFS/AFSC/NMML)

Ice Seals:

Ice seals require sea ice for birthing, pup rearing and resting. As ice is melting earlier in the year, pups are unable to complete their 6 week nursing period due to the premature collapse of shelters, exposing them to the elements and predators (Greenpeace, 2012). In 2002, 75% of Harp seal pups died due to lack of ice (Carillo-Rubio, 2011).

Pup counts and the total number of Northern Fur Seal between 1978 and 2008. The decrease in total pup counts (000's) is notable. (COSEWIC Assessment and Status Report on the Northern Fur Seal in Canada, 2010)
Pup counts and the total number of Northern Fur Seal between 1978 and 2008 on St. Paul I island. The decrease in total pup counts (000’s) is notable. (COSEWIC Assessment and Status Report on the Northern Fur Seal in Canada, 2010)

Bowhead Whales:

Ice-free waters will potentially impact permanent marine mammals. Bowhead whales calve under sea ice as it provides a safe environment from Killer whales, their primary predators (Moore and Laidre, 2006). The future lack of sea ice is likely to increase predation on whale calves, decreasing the reproductive success of the species and decreasing global population. Increased exposure to the sun may also be detrimental as these whales are heat intolerant, and don’t have an ability to combat this.

Bowhead Whales calve under the protection of the sea ice. (Image: Department of Fisheries and Oceans Canada)
Bowhead Whales calve under the protection of the sea ice. (Image: Department of Fisheries and Oceans Canada)

This brief overview of some of the largest and most prevalent Arctic organisms provides a good indication of the fragility of the community assemblage present in this ecosystem.

Artists impression of the Arctic ecosystem and ultimately the organisms at risk from climate change (Image: Oceans North, The Pew Charitable Trust)
Artists impression of the Arctic ecosystem and ultimately the organisms at risk from climate change (Image: Oceans North, The Pew Charitable Trust)

References:

Carillo-Rubio L (2011). Seals and their race against climate change. Climate Institute. www.climate.org/topics/ecosystems/seals-battle-climatechange.html [Accessed: 22/03/17]

Chadwick VJ & Fischbach AS (2008). US Geological Survey Factsheet 2008-3041. Pacific Walrus response to Arctic sea ice losses.

Cooper LW, Ashijian CJ, Smith SL, Codispoti LA, Grebmeier JM, Campbell RG & Sherr EB (2006). Rapid seasonal sea-ice retreat in the Arctic could be affecting Pacific walrus (Odobenus rosmarus divergens) recruitment. Aquatic Mammals, 32, 98–102.

Comiso J, Parkinson C, Gerston R, Stock L. (2008). Accelerated decline in the Arctic sea ice cover. Geophysical Research Letters. 35 (1), 41-49.

Derocher, A.E., Lunn, N.J., and Stirling, I. (2004). Polar bears in a warming climate. Integrative and Comparative Biology, 44, 163-176.

Greenpeace. (2012). Climate Change Impacts on Arctic Wildlife. Technical Report. (Review), 3-14.

Simmons L, Firman R. (2014). Experimental evidence for the evolution of the mammalian baculum by sexual selection. Evolution. 68 (1), 276-283.

Sonne C, Dyck M, Riget F, Jensen JE, Hyldstrup L, Letcher R . (2015). Penile density and globally used chemicals in Canadian and Greenland polar bears. Environment Research. 137 (1), 287-291.

Sonne C, Leifsson P, Dietz R, Born E. (2006). Xenoendocrine Pollutants May Reduce Size of Sexual Organs in East Greenland Polar Bears (Ursus maritimus). Environ. Sci. Technol., 40 (18), 5668–5674.

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Human’s naivety towards artificial manipulation of the nitrogen cycle has devastating effects for aquatic ecosystems!

Posted on by Zac Blair

Why care about nitrogen?

natural-nitrogen
Figure 1. Growth of marine plants affected solely by natural nitrogen sources. Source: https://www.esa.org/
artificial-nitrogen
Figure 2. Growth of marine plants affected by artificial nitrogen sources, showing increased algae growth and limited oxygen availability. Source: https://www.esa.org
dead_fish0834
Figure 3. Death of trout, as a result of reduced oxygen availability. Source: http://www.edupic.net

 

 

 

 

 

 

 

 

Nitrogen ranks fourth as the most common chemical element in living tissues. Before human contribution to the nitrogen content in the atmosphere, nitrogen was a major limiting factor controlling the functioning of ecosystems (Marris, 2008)! Despite 78% of earth’s atmosphere being nitrogen, most plants and animals must wait for the nitrogen to be ‘fixed’. This occurs through its bonding with hydrogen or oxygen to form ammonium and nitrate (Fields, 2004).

The current measurement of fixed nitrogen occurs in tetragrams (Tg), which is equal to a million metric tons of nitrogen. It is estimated that the rate of natural nitrogen fixation on land is 140Tg of N per year (Vitousek et al., 1997). Surprisingly, human activities have resulted in an extra artificial nitrogen fixation of 218Tg of N per year (Vitousek et al., 1997)!

nitrogen-cycle
Figure 4. Human-driven global nitrogen changing factors have increased in a similar trend to that of the human population, except for industrial N fertilizer, which has increased at a far greater rate – growing exponentially in 1975. Source: https://www.esa.org

More worryingly is that by 2050, if predicted population trends are accurate then artificial N fixation will reach four times that of the natural production rate(Tilman & Lehman, 2001)!

Why is this important?

One of the biggest problems nitrogen poses to aquatic ecosystems, is its ability to form nitric acid through complex chemical reactions! This acid results in increasing the concentration of H+ in freshwater environments. This results in the PH of the water decreasing. A decreasing PH can result in an increase in the concentration of trace metals (Lee & Saunders, 2003). This occurs due to decreased metal sedimentation. The settling of dissolved aluminium reduces phosphate availability and therefore affects the phosphate cycle (Camargo & Alonso, 2006).

This is devastating! Phosphates are involved in the formation of ATP during respiration, and this ATP is essential for the normal functioning of an organisms metabolism, and without proper functionality, death will occur. A PH below 6 seems to be the threshold for significant damage. In fish, arrested development of embryos can occur, resulting in skeletal deformities (Camargo & Alonso, 2006).

fish-embryo
Figure 5. Zebrafish embryos at normal oxygen conditions (normoxia) and severe hypoxia conditions (anoxia), showing the developmental arrest of embryos. Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC34668

High nitrogen levels can disrupt ionic regulation, which results in molluscs, insects, fish and amphibians suffering from a deficit in calcium. This causes issues with bone development and shell maturation. In terms of the food chain, the reduced PH of aquatic environments causes a depression of net photosynthesis in planktonic and attached algae (Eisler, 2012) . This is due to the increased growth of algae which can ‘cloud’ the water preventing light penetration, as well as through disproportional oxygen consumption.

Moreover, the decline in dissolved oxygen can promote the production of hydrogen sulphide by anaerobic bacteria. Hydrogen sulphide can further reduce the availability of oxygen, due to it accumulating at the waters surface (Smith & Oseid, 1974)! This is a huge problem as dissolved oxygen is essential to the respiration of aquatic organisms, and without it, death is inevitable!

Are humans really responsible?

In short, yes, we are to blame!

table

If the current trend continues, not only will the current effects be amplified, resulting in a greater number of deaths, but the cost of aquatic organisms as a source of food will sky-rocket!

References

Camargo J, Alonso Á. (2006). Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment. Environment International, 32(6), pp.831-849.

Eisler R. Oceanic acidification. (2012). 1st ed. Boca Raton: CRC Press

Fields S. (2004). Global Nitrogen: Cycling out of Control. Environmental Health Perspectives, 112(10), pp.556-563.

Lee M, Saunders J. (2003). Effects of pH on Metals Precipitation and Sorption: Field Bioremediation and Geochemical Modeling Approaches. Vadose Zone Journal, 2(2):, pp.77-185.

Marris, E. (2008). Nitrogen pollution stomps on biodiversity. Nature, 1, pp.1-3.

Smith L, Oseid D. (1974). Effect of Hydrogen Sulfide on Development and Survival of Eight Freshwater Fish Species. The Early Life History of Fish, 1, pp.417-430.

Tilman D, Lehman C. (2001). Human-caused environmental change: Impacts on plant diversity and evolution. Proceedings of the National Academy of Sciences, 98(10), pp.5433-5440.

Vitousek, P., Aber, J., Howarth, R., Likens, G., Matson, P., Schindler, D., Schlesinger, W. and Tilman, D. (1997). Technical Report: Human Alteration of the Global Nitrogen Cycle: Sources and Consequences. Ecological Applications, 7(3), pp.737-750

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