We’re happy to share the first MARS podcast, which can be streamed and freely downloaded from the Soundcloud widget above. Join us on the banks of the River Brun in Burnley in North West England to meet Steve Ormerod, Professor of Ecology at Cardiff University, chair of the RSPB council and co-leader of the MARS project catchment segment.
On a cold, blustery spring morning with dippers flitting past and robins singing in the trees, Steve tells us about the history of the Brun, and its recent restoration after years of pollution. Steve explains the concepts of freshwater stressors and ecosystem services, and tells us about his work with MARS.
This week we continue our Meet the MARS Team feature with an interview with Tuba Bucak, a PhD researcher from the Middle East Technical University in Turkey. Tuba’s research uses computer modelling techniques to study the potential impacts of climate change on freshwaters in the Mediterranean region.
1. What is your focus of your work in MARS, and why?
My work in MARS focuses on the effects of multiple stresses on a catchment scale. I am involved in Task 4.2 (Southern river basins) and our study area is Lake Beyşehir catchment in Central Anatolia, Turkey.
2. Why is your work important?
What we are doing is not only understanding freshwater ecosystems, in the end we are hoping that our outcomes will help decision-makers to implement measures to protect freshwaters. My study lake is the largest freshwater lake of Turkey and serves as an irrigation and drinking water supply. Considering the semi-dry climate of the region and intense agricultural practices, water use for irrigation is the most important stress driver in the basin.
Climate change may also exacerbate the effects of excessive water use, as expected scenarios for the region project an increase in temperature and a decrease in precipitation. Hence, to maintain the ecological status of lake in the future, we should be able to link the stressors with the ecosystem services and develop mitigation measures for the future.
3. What are the key challenges for freshwater management in Europe?
The key challenge is keeping the balance between the demands of the current society and the need to protect freshwater ecosystems. Generating scientific theory behind efficient management strategies is important, but convincing stakeholders (decision makers) to implement management strategies is the most difficult task, at least in Turkey.
4. Tell us about a memorable experience in your career.
My most memorable experiences have mostly happened on fieldwork. I think the best part of studying ecology is being in the field and having a real contact with the environment where you are working. In my first field experience, I was totally inexperienced, it was even my first camping experience! It was a long journey to the west of Turkey and we were in the field for 2 weeks, camping 2-3 days at each lake whilst conducting very intense sampling. These were remote lakes on which there was little information, hence every sampling trip was with full of surprises.
My second memorable experience is from my Master’s degree. We conducted an in-situ mesocosm experiment in a lake close to our university. It was also very intense field work, lasting for 4 months, involving setting up and running mesocosms. I remember me and my mesocosm partner (Ece), going to the sampling at 8:00 am and leaving the lake at almost 8:00 pm. Then our adventure continues at the lab (filtering all those samples) until 3:00 am! It was possible to freeze the samples and do the analyses later, but I don’t know, when you are young you don’t think that much…but it was good that we both lost 5 kg that summer due to intense field and lab work!
5. What inspired you to become a scientist?
I never thought about the possibility of doing anything else other than being a scientist. I always like watching documentaries about nature and imagining myself being there. Being a documentary producer can also be fascinating but if you want to understand natural processes, you should focus deeper. Hence being a scientist/ecologist seemed to me the best way to do what I want.
6. What are your plans and ambitions for your future scientific work?
Firstly I want to finish my PhD and to feel that I have accomplished that project. It will be a small step for humanity but very big step for me! I am also planning to learn more about marine sciences as well. My Master’s and PhD mostly focus on freshwater and I think it will be interesting if I can work on marine sciences as well. I want to acknowledge Arthur C Clarke at this point. He is very inspiring to me, and he said “How inappropriate to call this planet Earth when it is quite clearly Ocean.”
The fifth IPCC report, published in 2014, states that climate-related risks to freshwater ecosystems will increase in the future if greenhouse gas concentrations in the atmosphere continue to rise. Reduced rainfall under future climate change is projected to reduce available surface water and groundwater in dry subtropical regions, increasing human competition for water and potentially reducing the amount of water available for natural ecosystems. The IPCC report suggests that changes in rainfall patterns are likely to cause increased periods of drought in the future, particularly in semi-arid regions, potentially threatening the diversity and functioning of lake ecosystems.
There are already examples of lakes which have been severely affected by reduced water levels, whether caused by low rainfall, human water abstraction, or a mixture of both. The Aral Sea between Kazakhstan and Uzbekistan has shrunk by more than 50% since Soviet irrigation projects were constructed in the 1960s and has high salinity levels that have resulted in huge reductions in biodiversity, although restoration projects are currently underway (for more, see Aladin et al 2009). Lake Akşehir, once one of the largest lakes in Turkey, almost entirely disappeared between the 1980s and 2000s as a result of intensive irrigation for crop farming, leading to extinction of two endemic fish species (see Jeppesen et al 2009, and this Turkish report by Murat Uysal and colleagues).
New MARS study
Freshwater ecosystems in semi-arid Mediterranean climates are projected to be particularly affected by climate-induced droughts in the future. A new journal article by MARS scientist Erik Jeppesen and colleagues in Hydrobiologia examines how lake and reservoir ecosystems located in these Mediterranean climates have been affected by changes to water levels and salinity in the past. The study gives a more comprehensive understanding of how Mediterranean climate lake ecosystems are affected by water and salinity levels: a valuable resource for scientists and policy makers looking to research, manage and conserve these freshwater ecosystems.
The team used long-term climate and ecological data (which varied in coverage, but broadly covered the latter part of the 20th century) on six lakes in southern Europe and the Middle East, and one in Brazil (in a similar semi-arid climate), alongside a literature review of similar past studies. They found that whilst each lake had individual characteristics, the broad trend was that changes in water levels and salinity had significant effects on the lake ecosystems, nutrient dynamics, nutrient concentrations and water quality.
The study’s literature review of existing studies on the topic found that water level reduction often results in higher nutrient concentrations, higher phytoplankton biomass and lower water transparency in both shallow and deep lakes and reservoirs. Similarly, the authors found that increases in lake salinity often “markedly alter the community composition of phytoplankton, zooplankton, macrophytes and fish and often lead to a decrease in the biomass and diversity of each of these organism groups.”
Impact of water level decreases
Water level changes were generally caused by reduced rainfall or increased water abstraction for human use. These factors are often related, as studies (for example Yano et al 2007 in Turkey and Rodriguez Diaz et al 2007 in Spain) have found that reduced rainfall as a result of climate change is likely to increase the demand for water abstraction, as communities look to use scarce water resources for irrigation and drinking.
Nutrient concentrations in lakes generally rise when water level drops, because although there is less ‘nutrient loading‘ (the term generally used for nutrients entering an ecosystem) from runoff of fertiliser and waste from surrounding towns and fields, the nutrients already in the shrinking lake are likely to be concentrated.
In many cases, this can lead to eutrophication, where high nutrient concentrations (especially of phosphates) cause a ‘bloom’ of plants and algae to grow, blocking light and causing low dissolved oxygen levels in the water (or hypoxia), which can kill or harm other aquatic animals, and make the water unsafe to drink or bathe in. In particular, shallower lakes with increased water temperatures might experience blooms of cyanobacteria, and especially of toxin-producing species such as Microcystis. Such cyanobacteria blooms have become common on Doiran Lake in Greece, as a result of lowered lake levels due to agricultural abstraction.
More variable and extreme climatic conditions may lead to sporadically extreme nutrient loading, for example when heavy rain causes flooding and the erosion of river banks and overflows of wastewater and sewage pipes.
Low water levels and plant populations
The team found that in some cases, macrophytes – aquatic freshwater plants – may actually benefit from minor water level reductions. Many studies in the article’s literature review found that when lake levels dropped, macrophytes – for example water lilies or oxygenating pondweed – flourished due to increased light levels and reduced turbidity (the ‘cloudiness’ of the water).
However, this is not always the case. In the team’s study at the coastal Lake Biviere di Gela in Sicily, Italy, reduced water inflows – as a result of abstraction for irrigation – led to the lake getting shallower and shifting from a clear, macrophyte-dominated ecosystem to one that was more turbid and phytoplankton-dominated. Even when lake levels increased, the lake remained dominated by phytoplankton blooms, and the macrophytes didn’t re-establish themselves, possibly due to a decrease in water quality.
Low water levels and fish populations
Lowered lake levels also have impacts on fish populations. Warmer water temperatures, a potential lack of dissolved oxygen and eutrophication, and the destabilistion of the lake thermocline (a thin layer of water that separates the warm surface layer and cold deep layer) can result in the loss of deep, cold water ‘refugia’ where fish can retreat from predators, sunlight and warmer, oxygen-poor water. Following a reduction of 32 metres in the depth of Lake Vegoritida in Greece between the 1950s and 2000s, populations of the native, cold-water dwelling European whitefish disappeared, and were replaced by populations of warm-water species which can survive in eutrophic conditions, such as roach and carp.
Variability in lake level also destabilises the littoral zone – the area of land immediately around the lake – which can have negative effects on plant growth and fish spawning. For example, at Lake Kinneret (or the Sea of Galilee) in Israel, low water levels meant that bleak – a tiny silver fish – couldn’t spawn in the stony habitats in the littoral zone, which are submerged during high water. Similarly, the same littoral zone provides habitat and shelter for young fish amongst submerged stones and vegetation. Low water levels mean that the potential of the littoral zone as a breeding location and ‘nursery’ area for young fish is lost.
Impacts of increased salinity
Reduced rainfall means that less water enters the lake system, causing increases in salinity as solutes in the water become more concentrated. The study suggests that even a small increase in water salinity can cause a significant loss of biodiversity, and alter the ways that the ecosystem functions. It can be difficult to disentangle the effects of increased salinity from the effects of reduced lake levels, as both are caused by reduced rainfall and water abstraction. However, the paper’s literature review revealed that many previous studies have reported that salinity is the most important factor in determining the ecology of Mediterranean lakes.
Higher salinity levels put the cells of many organisms under osmotic stress, where the concentration of solutes in the surrounding water body affects the ways in which water is passed in and out of an organism’s cells. Daphnia – an important group of microscopic species that support many freshwater food webs – have a low salinity tolerance (although it is higher in some Mediterranean species).
Fish are least tolerant to salinity in their juvenile stages – potentially inhibiting the reproduction of existing populations – and salt-averse species may be replaced by salt-tolerant species such as the three- and ten-spined stickleback in highly saline lakes. Macrophyte diversity may also decrease, due to difficulties in plant germination, and the success of a small number of salt-tolerant species.
In emphasising the impact that salinity levels can have on freshwater lake ecosystems, Jeppesen and colleagues state that “when the salinity increase is high (e.g. from freshwater to brackish levels) its effects [on the ecosystem] may in some cases override all other environmental and pressure factors such as temperature or eutrophication.” They suggest that under future climate change scenarios, salinisation of freshwater lakes may also be increased by rising sea levels.
Low water and high salinity: lessons for water management and policy
This study looks to historical climate and ecological data and studies to give an indication of how lakes and reservoirs in semi-arid Mediterranean climates are likely to respond to the linked factors of future climate change and increased human demands for water in the future. In providing a comprehensive picture of the ways in which lake ecosystems respond to reduced water levels and increased salinity, it gives a valuable set of insights for water managers and policy makers seeking to manage, conserve and potentially restore these ecosystems.
Erik Jeppesen and colleagues provide a brief set of environmental management recommendations for these lake ecosystems, emphasising ‘integrated water management‘ that involves the reshaping of planning processes, the coordination of land and water use, the recognisation of water quantity and quality linkages, the sustainable use of surface water and groundwater, and the protection and restoration of natural systems and inland water storage.
The techniques of this ‘integrated’ management are described by the authors as ‘win-win’ and include: promoting sustainable water use, such as water pricing and water use prioritisation; control over abstraction of surface and ground water; implementation of water safety technologies; efficient water usage and conservation technologies; the reduction of water loss and water friendly farming; and increasing the storage capacity of water in the drainage basin through reforestation and controlled drainage.
These are long-term and complex issues – with an element of uncertainty in them – to which there are no simple solutions. However, by looking to the past, studies like this provide valuable information on how we might manage our freshwaters in the future.
Urban rivers are often amongst the most heavily stressed freshwater ecosystems, often polluted, abstracted, channelled, culverted and canalised. The River Lea in London is no different. The Lea rises in the countryside north of London, then flows through the north and east of the city (partly by way of man-made navigable channels known as the Lee Navigation and a network of channels through the Olympic Park built for the 2012 Games) to meet the River Thames.
Hi Ben, tell us about the River Lea: where does it flow through, and through what kind of environments? What’s the ecology of the river?
The River Lea (or Lee) flows 142 miles from its source in the Chiltern hills to Trinity Buoy Wharf on the Thames at near Canning Town, East London. It travels through heavily agricultural areas of Hertfordshire before entering London, on its journey through the capital it suffers from heavy pollution from a range of sources.
You may find it surprising that this river supports a range of ecosystems. Kingfishers are regularly seen from our office on the river in Bromley by Bow, along with plenty other wildfowl. A pollution incident in 2013 killed thousands of large fish that we didn’t know could live in a river so polluted. There is evidence to show that this fish population is recovering, though lack of habitat is a constant threat.
Where and how do Thames21 work on the Lea?
Thames21 is an environmental charity, officially established 11 years ago, we work with communities in London to improve waterways like these for people and for wildlife. Our Love the Lea campaign focuses on the rivers of the Lower Lea Catchment and sets out to inform local people about this pollution and how they can make a difference. We’re educating 32,000 young people by the end of 2016. We also take practical action to reduce pollution by installing sustainable drainage systems in the catchment area and introducing vegetation to the river in the form of reedbeds.
How serious is the pollution of the Lea? Where does the pollution come from?
Thames21 have tested the water quality regularly with University College London over the last few years, and at times the level of pollution is 40 times higher than EU standards! Rainwater washing off the densely populated areas that border the river often flows straight into the Lea and its tributaries, taking with it oils and other pollutants from roads. Additionally badly connected plumbing from households and commercial businesses in the catchment mean that wastewater enters the surface water drains and then goes straight into the river.
The water company Thameswater reckon despite their hard work, there’s about 60,000 of these ‘misconnections’ across London. Another key pollution source is sewage overflows. It’s estimated that these occur on a weekly basis in the Lea Catchment – they happen when our outdated sewage network cant cope with the amount of sewage in the system, which then overflows into the river.
What are the effects of the various pollutants on the Lea ecosystems?
These pollutants have cause serious effects on the Lea and tributaries. In many places this pollution can be smelt or seen, in Tottenham its common to see huge chunks of matter floating out of the Pymmes Brook which I assume must be raw sewage from overflows.
The lowered oxygen levels make it hard for aquatic life to survive, and high levels of nitrates encourage increased vegetation growth which covers the water’s surface (eutrophication), and duck weed and pennywort block sunlight, which affects the plants and organisms living in the river. Sewage fungus – a pale fungus which lines the river bed and banks – is also common on the smaller tributaries near outfall pipes.
What projects and initiatives do you run with Love the Lea to address these problems?
Reedbeds break down pollutants within a waterway, and provide habitats for fish and other wildlife. Installing reedbeds can be difficult within the constraints of an urban river, so we’ve had to come up with novel ways of bringing reeds to the rivers. Recently we’ve constructed large vegetation frames and attached them to sloping concrete banks creating ‘green walls’. This 320m green corridor will not only tackle pollutants, but has provided some much-needed habitat on a section of the river devoid of vegetation.
Our next reedbed project will bring floating ecosystems to the most polluted section of the Lea Navigation in Tottenham. These state of the art reedbed designs are being installed in an area of the river which is too deep for traditional reed planting. As they are floating, the reed’s root structure hangs within the watercourse – more pollution is broken down than in traditional reedbeds, and fish can shelter and feed in the roots.
We have a programme of green infrastructure projects going on across the Lea Catchment, we’re installing simple ‘rain planter’ boxes on community buildings and schools, taking rainwater off roofs reducing the amount of water in the sewers at one time which in turn reduces sewage overflows. We’re creating roadside rain gardens in unused green spaces, these process polluted road runoff and improve the aesthetics of an area.
Finally, we’ve a series of large-scale sustainable drainage systems on a tributary called the Salmons Brook in Enfield. We’re also sticking small signs on street drains to educate people that these drains lead straight to our rivers, an effective technique commonly seen in the USA and Australia.
Public engagement is important to your work: can you tell us a little about it?
Public engagement runs in conjunction with all our practical work; engaging people with the urban water cycle, and how our actions affect rivers. In addition to our classroom sessions, we are engaging people in many other ways. Our Love the Lea stall pops up at events throughout the catchment, we use games and fun activities to get the message across. We hold public events like our annual Love the Lea festival, with music, crafts and outdoor theatre, and have commissioned an art-science project Surface Tension, an intriguing mix of field recording, music and photography, which will produce a book, CD and exhibition at Stour Space, Hackney Wick in April.
Today is World Wetlands Day, where people and organisations around the world get together to talk about the importance of wetlands – the marshes, paddies, swamps, peatlands, bogs and fens that can help reduce the risk of flooding, ‘lock up’ carbon from the atmosphere and provide clean, filtered drinking water for humans, and habitat for an array of plants and animals.
Founded by Ramsar, and held on the 2nd February each year, World Wetlands Day marks the date of the 1971 adoption of the Convention on Wetlands in Ramsar, Iran on the shores of the Caspian Sea. To mark the day, we have a guest article by Kevin G Smith of the IUCN Global Species Programme on water and wetlands in the Eastern Mediterranean.
A two-year study involving scientists from across the Eastern Mediterranean has shown that freshwater biodiversity in the region is in an alarming state. With almost one in five species threatened with extinction, and a number of species already extinct, urgent action is required to restore and protect wetlands and flow regimes, and to adopt integrated water resource management practices that incorporate biodiversity needs.
Competing demands for water
In many regions of the world that are facing significant levels of water stress, there is often a perceived dichotomy between the provision of water for people (e.g. for irrigation) and for the ‘environment’ (biodiversity). When faced with this choice, the needs of biodiversity are, at best, usually only considered if there is any water ‘remaining’ once all other uses have been catered for. The notion that healthy freshwater ecosystems (functioning as ‘natural infrastructure’) that support biodiversity will provide, store, and purify water, and also provide many other valuable ecosystem services (e.g. food, flood protection, recreation) is not widely appreciated. In addition, the information required to inform this decision-making process about the needs of biodiversity is usually lacking.
Nowhere is this situation more apparent than in the Eastern Mediterranean region (Turkey, the Levant, and Euphrates and Tigris catchment), where the decision-making processes governing water resources are largely focused upon requirements for irrigation and energy production. This approach, compounded by impacts of climate change and pollution, has led to extensive loss of wetlands (e.g. Lake Amik in Turkey, and Azraq Oasis in Jordan), an alarming reduction in ground water levels, and a reduction and alteration in water flows across the region (e.g. the Qweik River in Turkey and Syria).
Mapping and conserving freshwater biodiversity
As a response to this situation the International Union for Conservation of Nature (IUCN) and partners have recently conducted a project in the Eastern Mediterranean that aims to address the lack of information on freshwater biodiversity, raise the profile of freshwater biodiversity conservation in the region, promote integrated water resource management practices, and better inform decision makers. Through this project, primarily funded by the Critical Ecosystem Partnership Fund (CEPF) and the MAVA Foundation, we identified the conservation status and mapped the distributions of all described species freshwater biodiversity in selected taxonomic groups in the Eastern Mediterranean. The project engaged scientists from across the region over a two-year period to assess the extinction risk (according the IUCN Red List Categories and Criteria) of every described species of freshwater fish, mollusc, dragonfly and damselfly, and a significant number of the regions freshwater plants. The findings, recently published in a report, are alarming.
Amazing diversity of freshwater species under threat
Despite the semi-arid nature of the region there is an amazing diversity of freshwater species. In total, 1,236 currently described species were assessed and mapped, of which just under 1/3 are found nowhere else on the planet (i.e. they are endemic to the region). However, almost one in five (19%) of these species, and over half (58%) of those endemic to the region, are threatened with extinction. Sadly, six species, all fishes, are known to have become extinct, and an additional 18 species (seven fishes and 11 molluscs) are possibly extinct. Molluscs and fishes are particularly impacted, with 45% and 41% threatened, respectively. Freshwater springs are identified as critical habitats, especially for threatened species as they often provide refuges during times of drought and where there is excessive water extraction.
Freshwater Key Biodiversity Areas
A number of sites that are of particular importance for the persistence of freshwater biodiversity have been identified across the Eastern Mediterranean. These sites, known as freshwater Key Biodiversity Areas (KBAs) are presented in a related report, also just published, on Freshwater Key Biodiversity Areas in the Mediterranean Basin Hotspot. These KBAs represent critical sites for freshwater biodiversity that may be used to inform future decisions on the designation of Ramsar sites (Internationally Important Wetlands) and inform environmental planning and private sector development – in particular to aid adherence to environmental safeguards policies and guidelines.
One example is the Haditha Karst (Cave) system KBA in Iraq, which is impacted by falling groundwater levels, supporting two endemic and Critically Endangered cave fishes; the Haditha cave fish (Caecocypris basimi), and the Haditha cave garra (Typhlogarra widdowsoni). Another is the Lakes Aci and Salda KBA, in Turkey, which support a number of threatened fish and molluscs including the endemic and Critically Endangered Aci Göl Toothcarp (Aphanius transgrediensI). The Lower Asi River KBA in Turkey supports high levels of threatened species (one of the highest in the region) and contains many critical wetland habitats such as Lake Gölbaşı, a small wetland close to the former (drained) Lake Amik and supports many important mollusc and fish populations.
Finding solutions: Integrated River Basin Management
One of the key recommendations stemming from this research is the need to adopt an Integrated River Basin Management approach (or similar strategy) in the Eastern Mediterranean to ensure that freshwater biodiversity is conserved, and to enable that wetland ecosystems to continue to provide ecosystem goods and services. This is especially important for transboundary waters where member states should fully implement the principles of the UN Watercourse Convention (UNWC) and accept responsibility for protection of connected ecosystems beyond national boundaries. Finally, there is an urgent need to set up and maintain long-term monitoring of freshwater biodiversity across the region if we are to prevent further species extinctions and secure functioning freshwater ecosystems for the benefit of people in the Eastern Mediterranean region.
World Wetlands Day can be followed on twitter by using the hashtag #worldwetlandsday
Kevin G Smith tweets @wildlifeinwater
The project was funded by the Critical Ecosystem Partnership Fund (CEPF), the MAVA Foundation and the Spanish Agency for International Development Cooperation (AECID), with contributions from the European Commission funded BioFresh Project, and the National Parks Autonomous Agency (OAPN) of the Spanish Ministry of Agriculture, Food and the Environment.
A third of global freshwater crayfish populations are threatened with extinction, according to a newly published report. A large team of researchers from the UK, Ireland, USA, Mexico, Australia and Austria, led by Nadia Richman at the Zoological Society of London, evaluated the extinction risk of the world’s 590 freshwater crayfish species based on the IUCN Red List categories.
32% of global crayfish species were classified by the team as ‘at risk of extinction’, a figure far higher than for most marine and land-dwelling animals and plants. This high extinction risk is unlikely to be helped by the fact that only a small proportion of global crayfish populations are covered by existing protected areas for conservation.
Bringing together scattered information on crayfish populations
The team undertook the huge task of collecting species-specific data on taxonomy, distribution, population trends, ecology, biology, threats and conservation measures for all 590 global species, using published and unpublished articles, government reports and personal communications up to 2009.
Interestingly, whilst crayfish were found in 60 countries across the world, 98% of species are endemic (i.e. found only in one place) to a single country. Four described species are now extinct, and 21% of species are ‘data deficient‘, because their populations haven’t been studied by scientists enough to assess their conservation status.
Stressors and threats to crayfish populations
The team used the ‘standard lexicon’ of biodiversity threats proposed by Nick Salafsky and colleagues in 2008 in Conservation Biology to categorise the threats to global crayfish populations.
Whilst the paper doesn’t go into a great deal of detail about the specific threats, it suggests that in the USA and Mexico, crayfish were largely threatened by the development of urban areas (e.g. modification of watercourses, reductions in natural habitat, increased water temperatures), dam construction (e.g. changing water flows and habitat fragmentation) and water pollution.
On the other hand, in Australia, species were predominantly threatened by the negative impacts of agriculture and logging (e.g. habitat alterations), climate change (e.g. changes to rainfall and temperature) and invasive species.
The impact of invasive species
The impact of invasive species was a major factor in many declining crayfish populations. In Europe, population declines of between 50% and 80% have been observed in the white-clawed crayfish (Austropotamobius pallipes) and 50% and 70% in the noble crayfish (Astacus Astacus). These declines were most acute at the northern end of the species’ geographical distributions, where rising temperatures have allowed the larger American signal crayfish (Pacifastacus leniusculus) to move in and outcompete the native species for habitat and food, with a number of negative effects on the wider ecosystem.
The signal crayfish has also brings the infectious and deadly water mould known as ‘crayfish plague’ (Aphanomyces astaci), to which it is immune, but European species are not. In Australia, young crayfish are eaten by invasive predators such as cane toads and feral pigs, species which also damage the crayfishes’ riparian habitat.
The authors of this study argue that their findings are another indication that not only are freshwater ecosystems under numerous threats, they are also inadequately protected by current conservation schemes. Richman and colleagues suggest that since there are limited resources available for conservation schemes, it is necessary to prioritise areas for protection – a key motivation for the collation of information on crayfish populations in this study.
A key challenge for conservation is that climate change may mean that crayfish populations need to shift their geographical ‘ranges’ to avoid warming temperatures, requiring a network of potential habitats (rivers, streams and lakes) with connectivity – i.e. those that crayfish can move between – in order to maintain their ecological resilience. The study suggests that two-thirds of Australian crayfish populations are at risk from climate-related threats, with poor connectivity between new, potential habitats.
At present, only a small proportion of crayfish populations are covered by existing protected areas. But how can this situation be improved? The authors suggest that freshwater biodiversity is all too often underrepresented in conservation planning schemes because we struggle to put an economic value on it, and conservation funds are more often channelled towards ‘charismatic‘ species with a recognised value.
This ‘if we can better value nature, then we can better protect it‘ argument has become more prevalent in conservation rhetoric in the last decade or so. But what new economic values of crayfish populations would persuade policy makers to put better protected areas in place for their conservation? Crayfish are important food sources for larger fish and bird predators, and a central part to cuisine and culture in southern USA states like Missouri and Mississippi.
But their status as rarely seen parts of large and complex freshwater food webs is likely to make any specific economic valuations of their populations tricky. It’s perhaps helpful to remember that these are beautiful, curious and ecologically important creatures with an intrinsic value in themselves. But how to recognise these values in conservation planning?
In essence, perhaps this is another example of a key issue facing freshwater conservationists: how do we persuade policy makers that our complex, biodiverse and increasingly threatened rivers and lakes are worth conserving and protecting?
REFORM, a European Union FP7 project which has worked to develop strategies for restoring damaged river ecosystems is holding its final project conference in the Netherlands in the summer.
The conference, titled “Novel Approaches to Assess and Rehabilitate Modified Rivers”, will be held at Wageningen in central Netherlands between 30th June and 2nd July at the Hof van Wageningen.
The conference organisers from the REFORM project describe that “The purpose of the conference is to enlarge awareness of the need and appreciation for the benefits of river rehabilitation. It will serve as a platform to present and discuss aspirations, challenges, analytical frameworks and novel approaches to improve our understanding of the causes and consequences of hydromorphological degradation and to enhance river rehabilitation.”
Bringing together over 200 participants from a range of backgrounds, the conference will host sessions on: understanding the impacts of hydromorphological modification and other stressors; achievements by river restoration projects; the effectiveness and costs of river restoration; the wider benefits of river restoration to society, flood protection, agriculture and hydropower; and how to link restoration science to policy, through a set of tools to assess river status and guide rehabilitation.
Registration opens on the 23rd January, whilst the deadlines for submission are 31st January (abstracts) and 20th March (full papers).