>>Led by scientists from Germany’s Leibniz-Institute of Freshwater Ecology and Inland Fisheries, the study looked at data relating to global populations of freshwater megafauna, gathered worldwide between 1970 and 2012. The 126 species that were counted within that period included 30-kg-plus (66-lb) animals such as river dolphins, beavers, crocodiles, giant turtles and sturgeons.

Overall, it was found that freshwater megafauna populations declined by a shocking 88 percent throughout the 42-year time span. This was twice as high as the loss of vertebrate populations on land or in the sea during the same period.<<

https://newatlas.com/freshwater-megafauna-decline-88-percent/61013/

PermeateFree said:

>>Led by scientists from Germany’s Leibniz-Institute of Freshwater Ecology and Inland Fisheries, the study looked at data relating to global populations of freshwater megafauna, gathered worldwide between 1970 and 2012. The 126 species that were counted within that period included 30-kg-plus (66-lb) animals such as river dolphins, beavers, crocodiles, giant turtles and sturgeons.

Overall, it was found that freshwater megafauna populations declined by a shocking 88 percent throughout the 42-year time span. This was twice as high as the loss of vertebrate populations on land or in the sea during the same period.<<

https://newatlas.com/freshwater-megafauna-decline-88-percent/61013/

What was the earlier thread about megafauna?

mollwollfumble said:

PermeateFree said:

>>Led by scientists from Germany’s Leibniz-Institute of Freshwater Ecology and Inland Fisheries, the study looked at data relating to global populations of freshwater megafauna, gathered worldwide between 1970 and 2012. The 126 species that were counted within that period included 30-kg-plus (66-lb) animals such as river dolphins, beavers, crocodiles, giant turtles and sturgeons.

Overall, it was found that freshwater megafauna populations declined by a shocking 88 percent throughout the 42-year time span. This was twice as high as the loss of vertebrate populations on land or in the sea during the same period.<<

https://newatlas.com/freshwater-megafauna-decline-88-percent/61013/

What was the earlier thread about megafauna?

One such study:

https://www.earthday.org/2018/05/18/populations-of-living-things-across-all-species-are-declining-and-this-is-very-worrisome/

PermeateFree said:

mollwollfumble said:

PermeateFree said:

>>Led by scientists from Germany’s Leibniz-Institute of Freshwater Ecology and Inland Fisheries, the study looked at data relating to global populations of freshwater megafauna, gathered worldwide between 1970 and 2012. The 126 species that were counted within that period included 30-kg-plus (66-lb) animals such as river dolphins, beavers, crocodiles, giant turtles and sturgeons.

Overall, it was found that freshwater megafauna populations declined by a shocking 88 percent throughout the 42-year time span. This was twice as high as the loss of vertebrate populations on land or in the sea during the same period.<<

https://newatlas.com/freshwater-megafauna-decline-88-percent/61013/

What was the earlier thread about megafauna?

One such study:

https://www.earthday.org/2018/05/18/populations-of-living-things-across-all-species-are-declining-and-this-is-very-worrisome/

More detail:

https://www.un.org/sustainabledevelopment/blog/2019/05/nature-decline-unprecedented-report/

PermeateFree said:

>>Led by scientists from Germany’s Leibniz-Institute of Freshwater Ecology and Inland Fisheries, the study looked at data relating to global populations of freshwater megafauna, gathered worldwide between 1970 and 2012. The 126 species that were counted within that period included 30-kg-plus (66-lb) animals such as river dolphins, beavers, crocodiles, giant turtles and sturgeons.

Overall, it was found that freshwater megafauna populations declined by a shocking 88 percent throughout the 42-year time span. This was twice as high as the loss of vertebrate populations on land or in the sea during the same period.<<

https://newatlas.com/freshwater-megafauna-decline-88-percent/61013/

> According to the scientists, lakes and rivers are home to one third of all vertebrate species worldwide

That’s a higher fraction than i expected.

> from 1970 to 2012, with the highest declines in the Indomalaya and Palearctic realms (−99% and −97%, respectively). Among taxonomic groups, mega‐fishes exhibited the greatest global decline (−94%).

Cripes! 99% decline between 1970 and 2012!

Haven’t read full article yet. https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14753

Forest wildlife populations decline 53% since 1970
https://www.worldwildlife.org/stories/forest-wildlife-populations-decline-53-since-1970

mollwollfumble said:

PermeateFree said:

>>Led by scientists from Germany’s Leibniz-Institute of Freshwater Ecology and Inland Fisheries, the study looked at data relating to global populations of freshwater megafauna, gathered worldwide between 1970 and 2012. The 126 species that were counted within that period included 30-kg-plus (66-lb) animals such as river dolphins, beavers, crocodiles, giant turtles and sturgeons.

Overall, it was found that freshwater megafauna populations declined by a shocking 88 percent throughout the 42-year time span. This was twice as high as the loss of vertebrate populations on land or in the sea during the same period.<<

https://newatlas.com/freshwater-megafauna-decline-88-percent/61013/

> According to the scientists, lakes and rivers are home to one third of all vertebrate species worldwide

That’s a higher fraction than i expected.

> from 1970 to 2012, with the highest declines in the Indomalaya and Palearctic realms (−99% and −97%, respectively). Among taxonomic groups, mega‐fishes exhibited the greatest global decline (−94%).

Cripes! 99% decline between 1970 and 2012!

Haven’t read full article yet. https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14753

Still trying to sort this out.

Indomalaya seems to be almost solely India. Must be really bad there. 99% population loss.

Populations of freshwater megamammals have actually increased by 60% over this time period.

Populations of freshwater megareptiles more than doubled between 1990 and 2007, before slipping backwards to roughly what they were before.

Freshwater megamammals include seal, dolphin, hippo, manatee, capybara, otter, tapir, marsh deer, and water buffalo (wild ones)

Freshwater megareptiles include only crocs and turtles.

Freshwater amphibians are salamanders.

Freshwater fish include salmon, trout, catfish, sturgeon, pike and others.

So almost all of the population decline must be freshwater fish.

Data after 2007 is rare, not sure why this is, but there is ten times as much population data for 2000 as there is for 2010. Is nobody measuring this, are there publishing delays, or are a heck of a lot of submissions being rejected?

As i say, still trying to sort this out.

When I read this the other day, my first thought was, I bet that’s the cichlids in Lake Victoria, there is something like a thousand species just there but they are being eaten by Nile perch.

Still trying to sort this out. Keep in mind that population loss is quite different to biodiversity loss. The statistical method is biased towards rarer species, which is as it should be.

For example, suppose that species A has 10,000 members in 1970 and 11,000 in 2010, and that species B has 1,000 members in 1970 and none in 2010. The statistical method they use won’t show a 0% change (total population) but a 45% loss (average of 10% gain and 100% loss). That’s good.

On the other hand, if species A initially has 10,000 members in River 1 and 1,000 members in River 2, which changes to 11,000 members in River 1 and none in River 2, this will also be reported as a 45% loss. Which I’m not quite so happy about because suppose an invasive species has none in a river initially, and 1,000 finally, then that is reported as an infinite gain (1,000 / 0) in numbers which throws out the whole analysis.

Are invasive species taken into account at all? Yes. The Common Carp is there. Another source says “The common carp is a contradictory fish, with wild native populations considered vulnerable to extinction and yet introduced populations are one of the worst invasive species in the world”. It’s listed for 12 river systems, in at least 9 of those river systems it’s invasive.

Picture of the common carp, an invasive freshwater megafauna.

mollwollfumble said:

Still trying to sort this out. Keep in mind that population loss is quite different to biodiversity loss. The statistical method is biased towards rarer species, which is as it should be.

For example, suppose that species A has 10,000 members in 1970 and 11,000 in 2010, and that species B has 1,000 members in 1970 and none in 2010. The statistical method they use won’t show a 0% change (total population) but a 45% loss (average of 10% gain and 100% loss). That’s good.

On the other hand, if species A initially has 10,000 members in River 1 and 1,000 members in River 2, which changes to 11,000 members in River 1 and none in River 2, this will also be reported as a 45% loss. Which I’m not quite so happy about because suppose an invasive species has none in a river initially, and 1,000 finally, then that is reported as an infinite gain (1,000 / 0) in numbers which throws out the whole analysis.

Are invasive species taken into account at all? Yes. The Common Carp is there. Another source says “The common carp is a contradictory fish, with wild native populations considered vulnerable to extinction and yet introduced populations are one of the worst invasive species in the world”. It’s listed for 12 river systems, in at least 9 of those river systems it’s invasive.

Picture of the common carp, an invasive freshwater megafauna.

>>The common carp or European carp (Cyprinus carpio) is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia. The native wild populations are considered vulnerable to extinction by the International Union for Conservation of Nature (IUCN), but the species has also been domesticated and introduced (see aquaculture) into environments worldwide, and is often considered a destructive invasive species, being included in the list of the world’s 100 worst invasive species. It gives its name to the carp family Cyprinidae. <<

>Are invasive species taken into account at all? Yes. <

No! Invasive species are a major reason for the disappearance of native species due to predation or habitat destruction. People are mainly responsible for these introductions.