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Tag: ecosystem change

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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Denial isn’t just a river in Egypt

Posted on by Sarah Hill
bog-river
Stream in the Redwood National Park

Humans (Homo sapiens) have been on this planet for at least 200,000 years (Hopkin, 2005) and throughout this time we have caused large changes to the river network. These modifications have occurred for many reasons;

  • Flood defence
  • Irrigation
  • Transport of goods
  • Drinking water
  • Power
  • Sanitation

But any changes made to a system has knock on effects to the organisms living there through changes in their biotic, living, and abiotic, non-living, environment. Human mediated change is no exception.

 

Pollution

As a result of human infrastructure and urbanisation rivers have become polluted with PAHs and heavy metals that have been washed off hard surfaces, such as roads. Industrialisation releases sulphur dioxide and nitrous oxide into the atmosphere which enters the rivers through acid rain. Sewage is also discharged into rivers in some areas, such as from houseboats and canal boats, which reduces the amount of oxygen available in the water for the organisms. Agriculture uses fertilisers and chemicals which, through the process of leaching and run-off, can end up in the river system. Pesticides and herbicides will kill insects and plants in the river system. Other chemicals are toxic to organism, as ammonia is to fish (Ip et al, 2001). Increasing nutrients in the rivers can result in eutrophication:

 

Flow modification

Some river channels have been deepened and widened to prevent flooding, resulting in their flow becoming faster. Flow has also been slowed in some rivers through the addition of dams, which have been built to supply drinking water and power to the public. Altering the flow of a river has wide spread effects on the ecosystem as it changes the abiotic and biotic composition. A slow flow results in higher temperatures (Dickson et al, 2012) and more sediment deposition (Christiansen et al, 2000) than a fast flow. Dams not only restrict the movement of the water but also organisms, which is a massive problem for migrating species such as eels and salmon. Irrigation results in a reduced water level which can be adverse for larger fish species and also alters the velocity of the flow.

blog-irrigation
Typical structure of surface irrigation

 

Introduced species

Introductions to rivers can be both intentional, eg for fishing, or unintentional, eg from the underside of boats. Only 1% of introduced species become invasive, affecting native species (Jeschke and Strayer, 2005), by competing for resources, preying on native species or introducing harmful diseases and parasites. This is a major problem in river systems due to their connectivity which mitigates the migration of these species to other reaches of the river making control and eradication difficult.

 

Harvesting

Excessive commercial harvesting of fish and shellfish in rivers can drastically reduce their numbers and the number of species. Eel and white bait numbers have declined significantly in the Waikato River, New Zealand, since the 1970s for this precise reason (Chapman, 1996). Reducing the population size of a particular species effects those that feed on them, such as other fish, birds, mammals and even reptiles.

blog-bird-and-snake
Snake eating a fish in the water and puffin with fish in its beak

 

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References

Chapman M.A. 1996. Human impacts on the Waikato River system, New Zealand. GeoJournal. 40, 85-99.

Christiansen T., Wiberg P.L. and Milligan T.G. 2000 Flow and sediment transport on a tidal salt marsh surface. Estuarine, coastal and shelf science. 50, 315-331.

Dickson N.E., Carrivick J.L. and Brown L.E. 2012. Flow regulation alters alpine river thermal regimes. Journal of hydrology. 464, 505-516.

Hopkin M. 2005. Ethiopia is top choice for cradle of Homo sapiens. Nature news. doi:10.1038/news050214-10.

Ip Y.K., Chew S.F. and Randall D.J. 2001. Ammonia toxicity, tolerance, and excretion. Fish physiology. 20, 109-148.

Jeschke J.M. and Strayer D.L. 2005. Invasion success of vertebrates in Europe and North America. PNAS. 102, 7198-7202.



RIP Great Barrier Reef: a Reef In Peril?

Posted on by Claire Murray

The threat of climate change for coral reef ecosystems across the world

By Claire Murray, University of Southampton student

 

the_sun
Losing Nemo? Are we seeing the demise of the Great Barrier Reef? Source: The Sun, 2016

Coral reefs are unique, awe-inspiring ecosystems; distinctively bright, bursting with biodiversity. However, they are already facing impacts of climate change. Headlines last year claimed the death of the most famous coral reef system on earth – the Great Barrier Reef. Whilst the story was greatly exaggerated, the possibility of the threat is all too real.

 

 

 

 

whitecoral
Good greef! Bleached coral, a contrast with the vibrant reef. Source: The Guardian, 2017

The importance of coral

Coral is a living organism, with algae it’s partnering, symbiotic component. Algae and coral are mutually dependent on each other for survival; providing food and a habitat respectively. However, coral bleaching is the loss of the symbiotic algae, occurring due to intolerance to changing environmental conditions such as increased sea temperatures. This is visually evident as a loss of pigmentation; replacing vibrant colours with the white colour of the coral’s calcium structure (Antonelli, et al., 2013). Increasing sea temperatures are a certain consequence of climate change, meaning that more coral bleaching could occur as temperatures increase in the near future (Antonelli, et al., 2013).

 

vibrantcoral
A vibrant coral reef ecosystem, without bleaching. Source: The Sun, 2016

What’s the catch?

Coral reefs provide important local ecosystem services, including coastal protection and fishery support (Hicks & Cinner, 2014). Corals are the main habitat-forming organism in the reef ecosystem – centrally important for biological and physical structure (Coker, et al., 2014). Various species are supported within the ecosystem, making reefs biodiversity hotspots (Hicks & Cinner, 2014). However, rising global sea temperatures are an environmental driver of the change being seen in ecosystems; threatening the benefits the ecosystem brings.

Threats to coral reefs are two-fold: global climate change pressures, and local anthropogenic pressures (Mongin, et al., 2016). Local stressors include pollution, sedimentation and overfishing (Ateweberhan, et al., 2013). Coral reefs are highly sensitive to the global risks of ocean acidification and warming (Ateweberhan, et al., 2013; Wolff, et al., 2015; Van Hooidonk, et al., 2014). The loss of the physical habitat ultimately threatens the abundance of marine life that depends on coral for its survival, reducing the resilience of the ecosystem as a whole.

 

acropora
Acropora coral, found in the Caribbean. Source: Pinterest, 2017

All bad news?

There is inequity of climate change impacts across coral reefs – for example, the Caribbean is likely to experience only relatively low levels of stress (Wolff, et al., 2015). The rates of environmental change also varies at different latitudes, meaning impacts will be staggered throughout the ecosystems on a global scale (Van Hooidonk, et al., 2014).

Despite the obvious negatives experience by the majority of coral reefs, it’s not bad news everywhere. Acropora corals seen on the northern Gulf of Mexico and on the Florida peninsula are extending their range – resulting in new, ‘novel’ ecosystems (Graham, et al., 2014). The emergence of new communities demonstrates the changing dynamics of the ecosystem.

The diverse environmental changes being seen globally are certainly going to impact coral reef ecosystems, and predominantly in a negative way. However some positives are likely; so not all hope is lost. But in the meantime, it might be worth visiting the Great Barrier Reef before it’s too late…

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References

Antonelli, P. L., Rutz, S. F., Sammarco, P. W. & Strychar, K. B., 2013. A coral bleaching model. Nonlinear Analysis: Real World Applications, Volume 16, pp. 65-73.

Ateweberhan, M. et al., 2013. Climate change impacts on coral reefs: Synergies with local effects,. Marine Pollution Bulletin, 74(2), pp. 526-539.

Coker, D. J., Wilson, S. K. & Pratchett, M. S., 2014. Importance of live coral habitat for reef fishes. Reviews in Fish Biology and Fisheries, 24(1), pp. 89-126.

Graham, N. A. J., Cinner, J. E., Norstrom, A. V. & Nystrom, M., 2014. Coral reefs as novel ecosystems: embracing new futures. Current Opinion in Environmental Sustainability, Volume 7, pp. 9-14.

Mongin, M. et al., 2016. The exposure of the Great Barrier Reef to ocean acidification. Nature communications, 7(10732), pp. 1-8.

Van Hooidonk, R., Maynard, J. A., Mazello, D. & Planes, S., 2014. Opposite latitudinal gradients in projected ocean acidification and bleaching impacts on coral reefs. Global Change Biology, 20(1), pp. 103-112.

Wolff, N. H. et al., 2015. Global inequities between polluters and the polluted: climate change impacts on coral reefs. Global Change Biology, 21(11), pp. 3982-3994.