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Crayfish and carp among the invasive species pushing lakes towards ecosystem collapse

Cam ac uk zoology department feed - Thu, 07/10/2021 - 00:01

Human activity and climate change are causing invasive non-native species to spread rapidly across the globe. Researchers have found that certain invasive species can push lake ecosystems beyond a critical ‘tipping point’, causing a sudden shift from healthy to degraded conditions that is difficult to reverse. 

Invasive fish such as Asian silver carp Hypophthalmichthys molitrix, and crustaceans such as American signal crayfish Pacifastacus leniusculus, were found to significantly reduce the abundance of other important organisms in lakes and degrade water quality. The findings, published today in the journal Global Change Biology, also provide guidance on the best ways to manage waterbodies.

Shallow lakes naturally exist in one of two alternative stable states: either healthy - with clear water with an abundance of vegetation, or degraded - with cloudy water dominated by algae. When a lake is in the latter state, algae use up all the nutrients in the water and block sunlight, preventing the growth of aquatic vegetation that would aid ecosystem recovery. 

Deteriorated, algae-dominated freshwater ecosystems also threaten the health and water security of human populations. Blooms of cyanobacteria, known as ‘blue-green algae’ can produce toxins that contaminate food webs and poison water supplies.

“Algal blooms represent one of the most significant threats to the security of the Earth’s surface freshwaters. Simply undoing the circumstances that triggered a tipping point will not restore the ecosystem - the road to recovery is slow and steep,” said Dr Sam Reynolds in the University of Cambridge’s Department of Zoology, first author of the report. 

However, although invasive species are recognised as a significant threat to global biodiversity, their impacts on ecosystem services may not be uniformly negative. Invasive molluscs, including the zebra mussel Dreissena polymorpha, were found to engineer the opposite biological and environmental response: they delay ecosystem collapse and potentially aid the recovery of degraded lake ecosystems.  

“Managers of drinking water reservoirs, for example, may be able to avoid the cost of dealing with blooms of harmful algae, by removing invasive crayfish but allowing established non-native zebra mussels to remain and act as biological filters,” said Professor David Aldridge, senior author of the report. 

He added: “Early detection and rapid response plans should always be our first line of attack. But in situations where invaders have already established and can no longer be eradicated, it may be appropriate to embrace their positive effects.”

The researchers focused on shallow lake ecosystems, but say that their framework could be applied to other critical ecosystems that experience catastrophic tipping points - such as coral reefs, kelp forests and desert shrublands.

This research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC).

Reference
Reynolds, S. A. & Aldridge, D. C.: 'Global impacts of invasive species on the tipping points of shallow lakes'. Global Change Biology, October 2021. DOI 10.1111/gcb.15893

Certain invasive, non-native species can disrupt lakes to the point of rapid ecosystem collapse, contaminating water for drinking, aquaculture and recreation, a new study has found.

Simply undoing the circumstances that triggered a tipping point will not restore the ecosystem - the road to recovery is slow and steep.Sam ReynoldsMark Philpott on FlickrAmerican signal crayfish


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Concentrate farming to leave room for species and carbon

Cam ac uk zoology department feed - Wed, 06/10/2021 - 09:47

Farming should be as high-yield as possible so it can be limited to relatively small areas, allowing much more land to be left as natural habitats while still meeting future food targets.

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Phylogenetic Signal and Bias in Paleontology

News from this site - Tue, 14/09/2021 - 10:40

The pattern of evolutionary relationships among species is crucial for understanding the diversity of life. Which species share evolutionary descent from a recent common ancestor, and which share one that is more remote? Figuring out this pattern for living species benefits from the presence of many kinds of information...

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First ever online field course

News from this site - Tue, 31/08/2021 - 12:44

First ever online field course The final week of the first-ever natural sciences online field course has just started! It has been a great success with 120 1st and 2nd year students actively engaging with a huge range of lectures, talks and activities. Due to the global pandemic, these students have all missed out...

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Integrated conservation strategies could simultaneously meet biodiversity, climate, and water objectives

Cam ac uk zoology department feed - Mon, 23/08/2021 - 16:02

To halt the decline of nature and meet Paris Agreement objectives, strategies must be designed and implemented to better manage land use for agriculture, infrastructure, biodiversity conservation, climate change mitigation and adaptation, water provision, and other needs.

A new paper by the Nature Map consortium, published today in the journal Nature Ecology and Evolution, presents an approach for spatial planning to support such integrated conservation strategies.

The study demonstrates that by jointly considering biodiversity, carbon, and water, synergies can be gained from conservation efforts compared to placing emphasis on any individual asset alone. Through strategic action in selected locations, significant benefits can be achieved across all three dimensions. However, conservation efforts need to be greatly scaled-up to meet global biodiversity and climate objectives. 

The paper sets out to determine areas of global importance to manage for conservation that would simultaneously protect the greatest number of species from extinction, conserve vulnerable terrestrial carbon stocks, and safeguard freshwater resources. 

This work is the first of its kind to truly integrate biodiversity, carbon, and water conservation within a common approach and a single global priority map. 

“To implement post-2020 biodiversity strategies such as the Global Biodiversity Framework, policymakers and governments need clarity on where resources and conservation management could bring the greatest potential benefits to biodiversity,” said lead author Martin Jung, a researcher in the IIASA Biodiversity, Ecology, and Conservation Research Group.

He added: “Biodiversity should not be looked at in isolation. Other aspects such as conserving carbon stocks within natural ecosystems should also be considered, so that synergies and trade-offs can be evaluated when pursuing multiple objectives.” 

“This type of approach can support decision makers in prioritising locations for conservation efforts, and shows just how much both people and nature could gain,” said Lera Miles, Principal Technical Specialist – Planning for Places, UN Environment Programme World Conservation Monitoring Centre.

She added “To be successful long-term, these areas must be managed effectively and equitably. That includes respecting the rights of, and empowering indigenous peoples and local communities.” 

“Maps for integrated land use planning can accelerate progress towards climate and biodiversity objectives and have many important additional policy uses, including helping to generate finance for natural climate solutions, improving carbon markets, and greening supply chains,” said Guido Schmidt-Traub, an author of the paper who has also written a related commentary in the same issue of Nature Ecology and Evolution.

The global priority maps can be explored interactively on the UN Biodiversity lab to support decision makers and generate insight and impact for conservation and sustainable development.

Reference
Jung, M., et al.: Areas of global importance for conserving terrestrial biodiversity, carbon, and water. Nature Ecology and Evolution. August 2021. DOI: 10.1038/s41559-021-01528-7

Adapted from a press release by The International Institute for Applied Systems Analysis (IIASA).
 

Managing a strategically chosen 30% of land for conservation could safeguard 70% of all terrestrial plant and vertebrate animal species, while simultaneously conserving around two-thirds of the world’s vulnerable carbon and clean water, according to a new study carried out by the Nature Map Consortium, involving the University of Cambridge. 

This type of approach can support decision makers in prioritising locations for conservation effortsLera MilesAdam Islaam | International Institute for Applied Systems Analysis (IIASA)Global areas of importance for terrestrial biodiversity, carbon and water (dark blue = highest priority, dark orange = lowest priority)


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified.  All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Pollinators: first global risk index for species declines and effects on humanity

Cam ac uk zoology department feed - Mon, 16/08/2021 - 16:01

The Global South may have most to lose from pollinator loss, with Latin America at particular risk due to crop exports and indigenous cultures.

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What Works in Conservation 2021

News from this site - Fri, 30/07/2021 - 10:58

This week, the sixth edition of Conservation Evidence’s flagship publication, What Works in Conservation , is published. What Works provides a freely-available, comprehensive overview of the expert assessment of evidence for the effectiveness (or not) of management actions collated within Conservation Evidence synopses. It...

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Monitoring the Meerkats of the Kalahari

Cam ac uk zoology department feed - Fri, 16/07/2021 - 08:55

Getting close was a challenge. Cracking it was key to an incredible 30-year study of the wild meerkats of the Kalahari. 

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Climate changed the size of our bodies and, to some extent, our brains

Cam ac uk zoology department feed - Thu, 08/07/2021 - 10:21

An interdisciplinary team of researchers, led by the Universities of Cambridge and Tübingen, has gathered measurements of body and brain size for over 300 fossils from the genus Homo found across the globe. By combining this data with a reconstruction of the world’s regional climates over the last million years, they have pinpointed the specific climate experienced by each fossil when it was a living human.

The study reveals that the average body size of humans has fluctuated significantly over the last million years, with larger bodies evolving in colder regions. Larger size is thought to act as a buffer against colder temperatures: less heat is lost from a body when its mass is large relative to its surface area. The results are published today in the journal Nature Communications.

Our species, Homo sapiens, emerged around 300,000 years ago in Africa. The genus Homo has existed for much longer, and includes the Neanderthals and other extinct, related species such as Homo habilis and Homo erectus.

A defining trait of the evolution of our genus is a trend of increasing body and brain size; compared to earlier species such as Homo habilis, we are 50% heavier and our brains are three times larger. But the drivers behind such changes remain highly debated.

“Our study indicates that climate - particularly temperature - has been the main driver of changes in body size for the past million years,” said Professor Andrea Manica, a researcher in the University of Cambridge’s Department of Zoology who led the study.

He added: “We can see from people living today that those in warmer climates tend to be smaller, and those living in colder climates tend to be bigger. We now know that the same climatic influences have been at work for the last million years.”

The researchers also looked at the effect of environmental factors on brain size in the genus Homo, but correlations were generally weak. Brain size tended to be larger when Homo was living in habitats with less vegetation, like open steppes and grasslands, but also in ecologically more stable areas. In combination with archaeological data, the results suggest that people living in these habitats hunted large animals as food - a complex task that might have driven the evolution of larger brains.

“We found that different factors determine brain size and body size – they’re not under the same evolutionary pressures. The environment has a much greater influence on our body size than our brain size,” said Dr Manuel Will at the University of Tubingen, Germany, first author of the study.

He added: “There is an indirect environmental influence on brain size in more stable and open areas: the amount of nutrients gained from the environment had to be sufficient to allow for the maintenance and growth of our large and particularly energy-demanding brains.”

This research also suggests that non-environmental factors were more important for driving larger brains than climate, prime candidates being the added cognitive challenges of increasingly complex social lives, more diverse diets, and more sophisticated technology.

The researchers say there is good evidence that human body and brain size continue to evolve. The human physique is still adapting to different temperatures, with on average larger-bodied people living in colder climates today. Brain size in our species appears to have been shrinking since the beginning of the Holocene (around 11,650 years ago). The increasing dependence on technology, such as an outsourcing of complex tasks to computers, may cause brains to shrink even more over the next few thousand years.

“It’s fun to speculate about what will happen to body and brain sizes in the future, but we should be careful not to extrapolate too much based on the last million years because so many factors can change,” said Manica.

This research was funded by the European Research Council and the Antarctic Science Platform.

Reference

Will, M. et al: ‘Different environmental variables predict body and brain size evolution in Homo.’ Nature Communications, July 2021. DOI: 10.1038/s41467-021-24290-7

The average body size of humans has fluctuated significantly over the last million years and is strongly linked to temperature. Colder, harsher climates drove the evolution of larger body sizes, while warmer climates led to smaller bodies. Brain size also changed dramatically but did not evolve in tandem with body size.

Our study indicates that climate - particularly temperature - has been the main driver of changes in body size for the past million years.Andrea ManicaHuman fossils illustrating the variation in brain (skulls) and body size (thigh bones) during the Pleistocene.


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified.  All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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