Background: When we build ponds in urban areas, they can play a number of important roles: managing floodwater, cooling the urban environment, removing pollution, improving the appearance of built-up areas and providing a habitat for wildlife. However, these different functions often require different forms of management, and so urban managers typically prioritise one or a small number of purposes. We were interested in the biodiversity value of ponds in Bradford in the UK.
What we did: My MSc student, Andrew Noble, surveyed a series of 21 sites across Bradford including 11 ponds that were prioritised for biodiversity, 6 ponds that were prioritised for amenity (usually park lakes and other ornamental features), and 4 ponds that were used as overflow ponds for water management. He surveyed aquatic plants and aquatic invertebrates to investigate patterns of biodiversity. This was then compared against what would be expected from high quality ponds of similar size (called a “reference site approach”). The results showed that the urban ponds were generally of very low quality, and that unsurprisingly the biodiversity ponds tended to contain higher numbers of animals and plants. However, this was not always the case and some amenity and overflow ponds contained more species despite not being managed for biodiversity. Finally, Andrew talked with managers who, while obviously enthusiastic about biodiversity, were unaware of important local factors that were influencing their sites, such as run-off from local sports fields which were likely contributing to algal blooms.
Importance: There have been a range of studies (including some by me) which have suggested that urban ponds can provide substantial benefits for biodiversity. However, these high value ponds are relatively rare, and it is important that we understand what factors result in some ponds being of high value while others are not. This study suggests that management could play a major role.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Poor ecological quality of urban ponds in northern England: causes and consequences”, was published in the journal Urban Ecosystems in 2014. You can find this paper at the publisher’s website.
Image credit: tpsdave, http://bit.ly/11ozTHF, Public Domain.
Background: Ponds have been identified as a very important habitat in the landscape. They enhance regional biodiversity, help control floodwater, reduce pollution in run-off from agricultural and urban land, and provide greenspace and biodiversity in urban environments. However, because of their small size (typically less than two hectares), they have been neglected by scientists until the last couple of decades.
What we did: This study used a large dataset of 454 ponds that had been surveyed in the north of England to identify all of the invertebrate and plant species that inhabited them. A wide range of physical, chemical and biological variables were also measured and, as the title of the paper suggests, we investigated which of these variables were related to the species richness of different plant and animal taxa. We were able to predict a reasonable amount of the diversity of invertebrates in general, but predictions varied between groups of invertebrates. In general, more shade and a history of drying up reduced the diversity of all groups.
Importance: It has been shown that landowners and managers tend to manage ponds and other natural resources using “received knowledge”. in other words, there is little evidence base for such management. Our study demonstrated a few important relationships which can be used to inform this kind of management.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Environmental correlates of plant and invertebrate species richness in ponds”, was published in the journal Biodiversity and Conservation in 2011. You can find this paper online at the publisher, or on Figshare.
Image credit: That’s one of mine, CC-BY 3.0.
Background: When an area is designated as a site for conservation or special scientific interest that is usually because one or more species of interest have been found or the community as a whole is unique or exceptional. However, the implicit assumption in this approach is that if you come back tomorrow then those species or that community will still be present. If the habitat is dynamic, with frequent population-level extinctions and colonisations, then it may be that this assumption does not hold. Pond ecosystems represent one case where the habitats are small and relatively easily affected by external variables and which may, as a result, vary in their conservation value over time.
What we did: Andrew Hull and Jim Hollinshead have been monitoring ponds in Cheshire (northwest England) for almost 20 years. A set of 51 ponds were surveyed in 1995/6 and again in 2005, meaning that we can test whether or not over this 10-year period there was any change in the conservation value of the ponds. Pond surveys recorded all plant and macroinvertebrate (i.e. invertebrates larger than about 1mm, which was the size of the mesh of the net) species in the ponds and we compared (i) the diversity, and (ii) the conservation value of the ponds between the two surveys. Plants showed similar levels of diversity in both surveys, so highly-diverse ponds in the first survey remained that way in the second. However, invertebrate diversity was not correlated between surveys, meaning that species rich ponds in the first survey did not necessarily remain that way. For both groups there was not correlation between conservation value (calculated based on the rarity of the species in the community) in survey 1 compared to survey 2.
Importance: Ponds are highly variable ecosystems and that is one of the reasons that they support such a wide range of species on a landscape scale. However, it seems that this variability may make it difficult to conserve them adequately, since conservation value is changing over time. This finding supports the conservation of pond clusters, rather than individual sites, which are more likely to contain a stable species pool.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Temporal dynamics of aquatic communities and implications for pond conservation”, was published in the journal Biodiversity and Conservation in 2012. You can find this paper online at the publisher, or on Figshare.
Image credit: Alison Benbow, CC BY 2.0, http://bit.ly/1l35Tdu
I had the pleasure this evening of introducing Prof Root Gorelick to give a lecture to the local Centre for Inquiry group here in Ottawa. I have seen him give a number of relatively provocative talks at conferences and I knew his engaging style and fascinating subject matter would make for an interesting evening. Some people have asked me to summarise the talk as they couldn’t make it, so here is my best attempt while it is still fresh in my mind…
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