A video post

Aside from some fairly irrelevant video clips, this video discusses the human thought and outlook our impact on biodiversity present day biodiversity loss. It discusses how humans ourselves may become extinct due to our dependence on ecosystem services and therefore why we should act to preserve it. It does however provoke thoughts of the decoupling of nature and human society, it further demonstrates how we are to act as stewards to preserve the world around us and does not necessarily consider human kind as natural or a part of the wildlife. 

Another issue that I feel is brought across in this video, is the identification of scientists as the sole provider of information on the human effects on the biosphere. On a local scale, communities have seen the decline in biodiversity, in particular with respect to invasive species for centuries and have therefore decided to act upon it through community led management approaches. For example forestry management in Orissa, India (Nayak, 2008).

The video does however highlight the issue of conservation and preservation of all things wonderful that exist on the Earth and not just figure-head species such as 'bicen and pandas'. For me this is important with respect to invasive species and their influence on species extinction. The impact of invasive species is often at a low trophic level, with the effects cascading down the trophic levels, or frog-leaping them entirely and removing the niche that was once occupied by an endemic or native species prior to invasion. Such is the case particularly with respect to intentional agricultural invasions in order to increase output to meet consumer demand.

The video also highlights human higher brain function and the role of our 'enhanced' intelligence compared to the wildlife around us, and how this should be utilised to better the world around us, for it has enabled us to advance technologically within our society. This again demonstrates the decoupling of mankind from nature, and as true as it may be, I feel that the more we forget about our association with nature, invasions will continue to take place, with more unintentional introductions taking place and the loss of species globally.

However, watch it and see how thought provoking it is for yourself from an ecologist point of view and perhaps about how the anthropocene is different with respect to extinction events. 

Are invasive species really that bad?

After reading articles on how invasive species are bad, how they reduce biodiversity and cause extinction through out competing the less adapted and more specialised native species, I stumbled across 'An Essay on some Topics Concerning Invasive Species' (Brown and Sax, 2004). This article brought a new insight to how to think about invasive species for myself, it views the occurrence of invasions as 'unintentional, uncontrolled experiments' that could potentially provide insights into how human caused invasions shape and alter ecological and evolutionary processes, in some respect 'generating and maintaining biodiversity'.

The article seemed to tap into the complexities of thought behind the issue of invading species, associating it with our fear of the foreign, our xenophobic thoughts, and how these thoughts are manifested in our actions to prevent the invasion taking place or doing our utmost to remove it once the invasion has taken place. This though is backed by our own ideas of associating the original environment as pristine, where in fact the conditions may have been worse prior to the invasion, or by our own doing the invasion has been allowed to become established through our presence. The conditions worsened by our own selves, this judgement of prior conditions is based on a decoupling of nature from our society, where human beings take on a role of stewardship instead of embracing the fact that we too are as intrinsically involved in nature as any other aspect of this world.

Brown, J.H and Sax, D. F. (2004) 'An Essay on Some Topics Concerning Invasive Species' Austral Ecology, "9, 530-536 (http://onlinelibrary.wiley.com/doi/10.1111/j.1442-9993.2004.01340.x/pdf)

Crayfish

For those who are interested, the inspiration for the return of the crayfish discussion:

http://www.bbc.co.uk/news/uk-england-coventry-warwickshire-15447581

(I dont know how to upload a video from the web other than it being on youtube or from my own computer so if anyone knows how to, it would be great if you could help)

The Case of the Signal crayfish

Oh yes, for those who did ecological patterns and processes last year, the tall tale of the signal crayfish is back for this post after reading an article on the BBC website inspired a small investigation.

The American signal crayfish Pacifastacus lenisculus has been detrimental in the decline in native European crayfish species. With its introduction via commercial culture (Alderman et al 1990) it not only establishes itself as a more adaptable and therefore more prevalent species within freshwater ecosystems but its resistance to the crayfish plague has been the most dominant advantage it has over the European crayfish. Gren et al (2008) are one of many articles discussing the issue of the signal crayfish carrying this plague, caused by the oomycete, Aphanomyces astaci Schikora (Alderman et al 1984), which when introduced to a new area threatens native populations with extinction. Gren et al (2008) discuss this issue in relation to Sweden due to the association of crayfish with recreational and cultural traditions, such as a cuisine delicacy corresponding to 0.5kg/person/year, and the impacts that this has on the presence of non-native crayfish. Crayfish caught in Swedish lakes accounts for about 35% of the total consumption and the 65% left over is imported internationally. In Sweden alone, signal crayfish account for 85% of the total number of crayfish harvested, however harvesting is not the only way that the presence of crayfish is being appreciated; crayfish are being caught be recreational divers.

The signal crayfish was introduced into Swedish waters in the 1960's to compliment native crayfish populations as they were in severe decline, partly due to exploitation but also, due to the fungus plague. As stated by Gren et al (2008), the idea with the introduction was for the signal crayfish to replace the native crayfish and 'fill the ecological niche' that was left behind by the loss of the native species. The issue with this introduction in the 1960's was that the knowledge behind the transference of the plague, which had been present in Sweden since 1907(Unestam, 1969), was not entirely certain, and it was discovered that the signal crayfish was a carrier of the plague. With this revelation, signal and noble crayfish therefore could not co-exist in the same environment for this reason alone, let alone the physical dominance of the signal crayfish out competing the native noble and its increased mobility. This was confirmed by a study by  Fiskeriverket and Natuvardsverket in 1998. This led to the imposition of regulations on the introduction of signal crayfish, however they were still being introduced by those who were able to obtain permits. The article concludes, after analyzing the impacts of economic factors on the occurrence of signal crayfish, that restrictions need to be imposed as the spread of the species is not likely to decrease from economic development, its spread can be described as independent from economic factors, the primary introduction alone was enough.

The article by Gren et all (2008) is one of many examples of how species in contemporary times have been facilitated to meet the increasing demands of the human population. This shows how the signal crayfish was purposefully introduced to supply the local populations of Sweden with a favoured delicacy. As to my previous post, this deliberate introduction has had dramatic implications on the populations of the local noble crayfish of Sweden, as Gren et al (2008) states, populations in areas have been driven to near extinction.


Alderman, D. J, Polglase, J.L, Frayling, M, Hogger, J. (1984) 'Crayfish plague in Britain', Journal of Fish Diseases 7. 401-405.

Alderman, D. J, Holditch, D, Reeve, I. (1990) 'Signal crayfish as vectors in crayfish plague in Britain', Aquaculture, 86, 3-6

Gren, Ing-Marie, Campos, Monica, Edsman, Lennart, Bohman, Patrik (2008), 'Incomes, Attitudes, and Occurrences of Invasive Species: An Application to Signal Crayfish in Sweden', Environmental Management, 43:210-220

Unestam, T. (1969) 'Resistance to the crayfish plague in some American, Japanese and European crayfishes, Report of Istitute Freshwater Research, 49, 202-209