Problems in paradise: the destruction of Hawaiian species

A few months ago I wrote a post on invasive species in Finland, and in particular on the North American beaver (Castor canadensis). I received a comment on how it is bold (or maybe the commenter meant reckless) to say that almost all invasive species are threatening the native species of the region. I began thinking of this comment, and tried to find some studies that proved that invasive species are beneficial for the subject ecosystem. Unfortunately, I only came up with sad tales. One very devastating example of invasive species is the Hawaiian Islands.

The Hawaiian Islands in the center of the Pacific Ocean are one of the most isolated islands in the world. Their endemic terrestrial species originate from some hundred species that migrated thousands of kilometers over the Pacific Ocean during several millions of years. Because of the immigration bottleneck and isolated evolution, the Hawaiian Islands have become a place for numerous distinctive and fascinating species. But it has also made the fauna and flora of the islands very vulnerable to various disturbances, such as human invasion and human-mediated invasions.

Nowadays almost a quarter of Hawaiian terrestrial species are non-native. Birds have probably suffered the most. Previously there were 11 native goose species in the Hawaiian Islands, but nowadays only one species is left: the nene (Branta sandvicensis), also known as the Hawaiian goose. The same has also happened to the native duck species; just two duck species are left (the Hawaiian duck, Anas wyvilliana and the Laysan duck, Anas laysanensis).

The nene, also known as the Hawaiian goose (Branta sandvicensis), is the only endemic goose species left in the Hawaiian Islands. © Sari Holopainen

The nene, also known as the Hawaiian goose (Branta sandvicensis), is the only endemic goose species left in the Hawaiian Islands. © Sari Holopainen

The main reasons for these extinctions are introduced predators (e.g. the feral cat and mongoose), and feral and game species (e.g. the mouflon, Axis deer and feral pig). There are almost 60 studies on domestic ungulates, but none have demonstrated any positive effects of them on native species. Ungulates stimulate the growth of grass among other things, leading to more grasses and less forest. And all this changes the light regime and fire resistance of an ecosystem. Grazing is therefore destructive to Hawaiian forests and to every native organism living in them. It has also been proven that the invasive vertebrate species of Hawaii have facilitated at least 33 invasive plant species. In addition to damages caused by grazing, feral pigs alter nutrient cycling and accelerate soil erosion.

The main problems caused by feral pigs are alteration to nutrient cycling and acceleration of soil erosion. © Sari Holopainen

The main problems caused by feral pigs are alteration to nutrient cycling and acceleration of soil erosion. © Sari Holopainen

There is still some light at the end of the tunnel, although it might be rather dim. The public has come to aid in the eradication of many species. Scientists and wildlife managers have concurrently begun multi-scale population monitoring, which includes aerial and ground-based visual surveys as well as trail cameras. To intensify and simplify the eradications even further, several hundred kilometers of management fences have been constructed. As an outcome of this some success stories have emerged; the eradication of rabbits and feral goats. Furthermore, the midway islands of Hawaii are now rat and non-native mammal free!

Unfortunately, it has been too late for some Hawaiian ecosystems. A key threshold has been crossed in some regions, and recovery of certain ecosystems may not be possible any longer. The populations of illegally introduced axis deer (Axis axis) have been reduced to some dozens, but their eventual eradication has been problematic, because assessing the number of remaining deers on private properties has proved difficult. The axis deer was introduced to provide game, so private properties owned by hunters act as reservoirs for the deer, from where they can be disperse to clean areas.

The main feral goat eradication was performed in 1980s, and nowadays the Hawaiian Islands are goat free. © Sari Holopainen

The main feral goat eradication was performed in 1980s, and nowadays the Hawaiian Islands are goat free. © Sari Holopainen

To conclude, I still dare say that almost all invasive species threaten native species. Even though some invasive species don’t harm all native species, we are always looking at nature as a complex ecosystem consisting of several species and functions. When introducing an alien species, we will always alter the pristine ecosystem.

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The Red List of Ecosystems: assessing the extinction risk of ecosystems

Alps and Krim waterfall ©Mia Vehkaoja

Alps and Krim waterfall ©Mia Vehkaoja

Most people are familiar with the concept of extinction, and are aware of the IUCN Red List of Threatened Species (RLTS), a classification of the Earth’s organisms into different categories based on their population levels and dangers facing their survival. RLTS was founded in 1964, and was initially considered the best way forward in global conservation. Unfortunately, the plan of documenting all living organisms of the planet has proven cumbersome and slow, and currently the project’s aim is to classify 160 000 species by 2020. That accumulates to only 8% of all species currently known to exist. The task seems daunting and never-ending. Although certain individual species have been brought back from the brink of extinction thanks to having their “specs” measured, the RLTS has been unable to curb or stop the increasing population decline of countless species.

As a list of individual species has proved inadequate to counter biodiversity loss, the next step forward was taken during the 2000s with the formation of the Red List of Ecosystems (RLE). The idea behind this is fairly simple; each ecosystem is compared to a set of criteria, assessed in terms of its risk of collapsing (meaning the disintegration of its functioning leading to collapses in biodiversity), and finally categorized according to its current functioning and stability. It is in fact a hazard assessment for the extinction risk of individual ecosystems. The criteria used in evaluating each ecosystem includes assessing how much of their original flora and fauna have been converted, degraded or destroyed, and how much of their original size remains.

Classification is pretty similar to that of the RLTS: ecosystems can currently be at no risk of collapse (least concern), at three different levels of being threatened (vulnerable, endangered, or critically endangered), or they may already be approaching a final state of degradation (collapse). We may also have too little information (data deficient) to make an assessment, or their health may not have been appraised yet (not evaluated).

Once classified, appropriate planning and management measures can be taken to enhance or restore ecosystem functionality, which often also improves the stability of societies living within the influence of these ecosystems. For example, wetland restoration benefits societies by providing cleaner water for household use and by preventing or lessening flood and drought damage.

The RLE is an important tool for communicating between ecologists, decision-makers, and developers. The system provides robust and straightforward guidelines that are applicable to all types of ecosystems around the globe. One noteworthy goal of the IUCN is to assess and showcase ecosystems that are currently doing well, not just those that are at risk of collapse. Such well-to-do ecosystems are important, so as to pinpoint the reasons and most efficient management practices that have led to their current health.

Desert in Dubai ©Mia Vehkaoja

Desert in Dubai ©Mia Vehkaoja

However, improvement is always necessary. One such avenue for improvement lies in getting nations to collaborate together in conserving ecosystems crossing borders. This would greatly improve the connectivity of landscapes, improving habitats for migratory species, species with large habitat area requirements etc. But when used jointly with other conservation measures, such as the assessment of ecosystem services, spatial management planning, and the IUCN RLTS, this new method seems very promising. Currently the aim of the IUCN is to have all the Earth’s ecosystems assessed by 2025. This will be carried out at the national and regional level, and results will be freely accessible in an online database.

For more info and case studies, go to http://www.iucnredlistofecosystems.org/about-us/red-list-ecosystems/

For a practical assessment guide, visit http://www.iucnredlistofecosystems.org/wp-content/uploads/2015/04/Rodriguez-etal-2015-A-practical-guide-IUCN-RLE_erratum.pdf

Starving polar bears and disappearing male turtles

At the moment we are living in the sixth wave of mass extinctions. The last one 65 million years ago is well-known to have been caused by an asteroid collision (and possible some other factors), after which non-avian dinosaurs became extinct. Currently animal species are disappearing at a rate of 100-1000 times faster than in normal situations. Climate change, habitat loss, pollution and overexploitation are considered the main reasons for this loss, and all of these are human-driven phenomenon. Climate change is a controversial subject, but nevertheless, we are already seeing the effects of it in our co-animals.

Let’s make a short overview of the changes that current climate warming has caused to natural systems. Some changes are direct, but there are also some more complex traits. Climate change-driven impacts are found to work through population abundance, species distributions, morphology and behavior, and eventually impacting community structures.

It is possible that the polar bear, at least as we know the species, will disappear due to climate warming. In the future it might still be possible to see white polar bears in zoos, such as Ranua Zoo in Finland.

It is possible that the polar bear, at least as we know the species, will disappear due to climate warming. In the future it might still be possible to see white polar bears in zoos, such as Ranua Zoo in Finland.

Where will the habitats shift?

Habitat shifting is one of the most obvious effects of climate change. It does not just mean moving pole-wards, but also upwards. The Edith’s Checkerspot, a North American butterfly species, has shifted its range both northward (92 km) and upward (by 124 m). During this same time period the temperature isotherms shifted 105 km northwards and 105 m upwards, which corresponds well with the butterfly’s range shift.

The habitat of some animals is not shifting, but disappearing. The arctic ice cover is becoming thinner and ice time is becoming shorter. Icy landscapes are the habitat that polar bears are adapted to. When summers grow longer, polar bears need to spend longer times on land or swimming in the sea. The future of polar bears seems gloomy, and it is expected that the majority of the bears will be lost during coming decades.

In stark contrast to the polar bears, some animals are able to utilize the new areas formed due to the lost ice. In Europe, wintering duck numbers have increased in northern waterbodies, while concurrently decreasing in southern and western parts of Europe. Some areas that were previously avoided because of their hostile winter climate are now used, for example Steller’s eiders (Polysticta stelleri) can nowadays winter in the ice-free parts of the Russian White Sea instead of the Baltic Sea.

 

Temperature mixes biology

Puffin food catching is becoming difficult because of climate change.

Puffin food catching is becoming difficult because of climate change.

Some species are decreasing, because climate change can crucially affect their breeding success. Vulnerable sea ecosystems have already been shown to be responding to the warming climate. The breeding time of the Atlantic puffin (Fratercula arctica) is usually dependent on North Atlantic Oscillation, except that the effects disappear during certain years. It is expected that this connection is lost due to climate change, possibly via its effect on the availability of the puffins’ fish prey. Researchers suggest that there might be climate-induced changes in the availability of their prey species. Warm sea surface temperatures have also been found to crash the breeding success of tufted puffins (F. cirrhata). Even though they can adjust their breeding phenology according to water temperature, prolonged warm seasons affect the fledging production of this sensitive species and can make their southern breeding habitats unsuitable for them.

Several bird species are known to have changed their phenology during the last decades: since 1937 31% of bird species in Britain, and 53% since 1939, have been found to show long-term trends of breeding earlier. At the same time, only one species has delayed its breeding. The same breeding pattern has been found in Finnish duck species. Ducks have also delayed their autumn migration during the last three decades. In addition, some amphibian species are breeding earlier in Britain now than 30 years ago.

Many natural systems are adapted to working in certain temperatures. If they are disrupted, there will be consequences. For example, the sex of many reptiles is determined by temperature. All the offspring of turtles develop into females in a warm climate, and into males in a cooler climate. Changes in temperatures affect their sex ratio, and a warming of 2 degrees C could make their populations highly female-skewed.

 

Climate warming releases diseases

Climate change can also affect the sensitive disease balance. Amphibian populations all over the world have been in drastic decline during the last few decades. One of the causes seems to be a deadly fungus, chytridiomycosis. What is extremely worrying, is that the fungus needs a warm climate, and due to climate change, epidemics can occur in new areas. The fungus has so far caused an extinction of at least 93 amphibian species, and is threating amphibian species globally.

Amphibian species all over the world are threatened by a new fungus.

Amphibian species all over the world are threatened by a new fungus.

 

In the hope of evolution

The changes seen now are so rapid that it is unclear how well animal populations, at least long-living ones, can adapt to the new circumstances. But if possible, natural selection could make the polar bears return to their roots, and begin behaving like brown bears again. Or, after seeing a document on polar bears spending their summers swimming and hunting walruses, one could speculate that polar bears could evolve into a true marine species, if there were enough time. Could we also trust evolution to change the limiting temperatures of turtle sex determination? However, all this is speculation, and requires that climate change does not progress too rapidly for long-living species. Models suggest that populations with temperature-dependent sex determination may be unable to evolve rapidly enough. There is a threat that we will lose species such as the polar bears and turtles, unless we play some more time for them by slowing down climate warming.

 

Can the polar bear become the brown again? Salt, an albino brown bear in Polar park Norway.

Can the polar bear become the brown again? Salt, an albino brown bear in Polar park Norway.

 

Read more

REPORT Regime shifts in the breeding of an Atlantic puffin population

Climate change and temperature-dependent sex determination in reptiles

Tufted puffin reproduction reveals ocean climate variability

Climate Extremes: Observations, Modeling, and Impacts

 

An Awful Lot of Voles every five years or so…

Grey red-backed vole (Myodes rufocanus) ©Sari Holopainen

Grey red-backed vole (Myodes rufocanus) ©Sari Holopainen

A recent hiking trip to Lapland got me thinking of voles. The little critters were absolutely everywhere, happily (or with a vengeance) gnawing at our rucksacks during the night in hope of finding food. Several notes left in hiking huts along the way gave more proof of their high numbers: two people had had their rucksacks eaten through and one had lost a bag of nuts when a vole ate a hole through the tent.

Back home in southern Finland, not hair nor hide of a vole. Why not? What actually constitutes a vole cycle, how does it work, and why does it periodically crash? And how does it affect other animals?

Voles can reach sexual maturity as early as three or four weeks, depending on the species in question. This combined with large brood sizes and giving birth to several broods during the breeding season means that when conditions are right there will be an Awful Lot of Voles (called the peak of the cycle). This leads to increases in the numbers of predators (e.g. stoats Mustela erminea and least weasels Mustela nivalis), which marks the start of vole population declines and crashes as their mortality increases. The whole cycle appears to take around three to five years in northern Europe, but it is not synchronous everywhere. Hence a deluge of voles in Lapland, while populations in southern Finland crashed last winter and currently remain small.

Vole populations fluctuate on a yearly basis. Graph by Hannu Pietiäinen.

Vole populations fluctuate on a yearly basis. Graph by Hannu Pietiäinen.

Voles are of course, paramount to many predators. During our hike we saw a hawk owl (Surnia ulula) and several rough-legged buzzards (Buteo lagopus). Signs of martens and stoats were numerous. Unfortunately the elusive snowy owl (Bubo scandiacus) did not make an appearance. These are all species whose life cycles are influenced by voles. They produce larger numbers of offspring during vole-rich years, while breeding may plummet to zero when vole cycles are down. Many strict vole eating owl species are nomadic, wandering large distances to ensure being in the right place at the right time when it comes to food. However, several owl species are residential and will not travel in search of food, e.g. the tawny owl (Strix aluco). For these species in particular the vole cycle does not only determine breeding success or brood size, but actually influences the number of breeding pairs in the total population, the timing of nesting onset, even a young owl’s entire life expectancy and quality of life. For example, the phase of the vole cycle (aka the nutritional state of an owl) during the first year of an owl’s life correlates with the number of parasites it carries as an adult. The vole cycle also determines at what age residential owls are recruited into the population as breeders (e.g. whether at one or two years of age), as owls will not breed if the female is too weak.

Phase of vole cycle affects nesting and owling survival. Modified from picture by Hannu Pietiäinen.

Phase of vole cycle affects nesting and owling survival. Modified from picture by Hannu Pietiäinen.

A worrying phenomenon has possibly begun to unfold during the last few decades concerning vole cycles. Twice the cycle has been disrupted, and an anticipated peak has not occurred. If disturbances in the cycle become more frequent, this will play havoc for countless northern species. The reasons behind this disturbance are unclear, but a warming climate with thin snow cover has been suggested.

Rough-legged buzzards use voles as their primary food source. ©Sari Holopainen

Rough-legged buzzards use voles as their primary food source. ©Sari Holopainen

Frogs love beaver-created wetlands

Amphibian and wetland loss is occurring globally at an increasing rate. Since the 1900s, approximately half of the world’s wetlands have been destroyed. During this time up to two-thirds of European wetlands were lost at a regional scale. This trend is reflected by the fact that 23% of Europe’s amphibians are threatened.

Wetlands in the boreal region are frequently constructed through the damming activities of an ecosystem engineer, the beaver (Castor sp.). They create and maintain special habitats by constructing dams. Beaver-created wetlands are open and sunny due to tree felling and flooding-induced tree mortality. They produce large quantities of woody debris and detritivorous invertebrates, e.g. chironomids and Asellus. Beaver ponds contain structurally heterogeneous vegetation.

Beaver-created wetlands contain structurally heterogeneous vegetation, as well as open water areas. © Mia Vehkaoja

Beaver-created wetlands contain structurally heterogeneous vegetation, as well as open water areas. © Mia Vehkaoja

According to our new study beaver-created wetlands increase frog species heterogeneity and abundance. There are only three native anuran species in Finland (the common frog, the moor frog and the common toad), and all of them were found in beaver ponds. The moor frog (Rana arvalis) was only found in beaver ponds, where the common frog (Rana temporaria) was also most abundant. The common toad (Bufo bufo) prefers deeper wetlands than the other two species, but because beaver ponds contain both shallower and deeper parts, it was also found from the beaver ponds.

Beaver wetlands offer high quality habitats for anurans and facilitate the occurrence of moor frogs. The shallow and warm water areas accelerate the hatching and metamorphosis of tadpoles. The rich aquatic vegetation provides attaching places for spawn and protection against predators. The abundant vegetal detritus, zooplankton and aquatic invertebrates offer nutrition for both larvae and adults. In addition, beaver-created wetlands create overwintering habitats that are less likely to freeze down to the bottom.

Both the moor frog (Rana arvalis) and the common frog (Rana temporaria) are the most abundant in beaver ponds. © Mia Vehkaoja

Both the moor frog (Rana arvalis) and the common frog (Rana temporaria) are the most abundant in beaver ponds. © Mia Vehkaoja

Beaver facilitation includes both habitat amelioration and resource enhancement. Frogs are not the only group that is benefitted by beaver activity. Other such groups are ducks, bats, woodpeckers and many invertebrates. These ecosystem engineers could be used in wetland restoration, and furthermore the beaver clearly promotes amphibian conservation.

Wetlands for citizens

Urban wetlands are typically multifunctional, offering several ecosystem services, for example water purification and recreational activities. Wetlands with several services are typically used by local people and even tourists are attracted to them in several areas. According to some studies, local people are quite well aware of the wetlands near them and support their preservation, while they might not be so aware of their functions.

More than one hundred river surfers gather every day in the Munich central park in Germany. The Isar River runs through the park and it is possible to surf in the Eisbach, a small artificial channel of the river. © Sari Holopainen

More than one hundred river surfers gather every day in the Munich central park in Germany. The Isar River runs through the park and it is possible to surf in the Eisbach, a small artificial channel of the river. © Sari Holopainen

Cultural ecosystem services, such as recreational services, are typically well known and utilized by local people. Several outdoor activities can be carried out in the wetlands, especially if they are surrounded by green parks. People can enjoy aesthetic values of wetland parks, which improves human physical and psychological health. Green areas, both forests and parks, are studied in Finland to prevent stress. Wetlands also regulate local climate, and offer pleasant city environments even during warm summers. When it is hot in the city (“urban heat islands”) due to dark materials on buildings and roads, green park areas can offer cooler pockets for the citizens and thus improve human health.

Sometimes wetland park areas can produce provisional services for local people. For example, beautiful wetland parks can also attract other than local people. Tourists willing to pay for recreational activities import money to the locals. Krka National Park in Croatia is a good example of provisional services offered by wetlands. Village of Skradin, situated at the entrance to the Park, benefits from wetland tourism. During the last few year, the park has been visited by more than 700 000 visitors annually. Before tourists, Krka river produced electricity for the city of Šibenik. In fact, Šibenik was the first city in the whole world with alternating current-powered street lights in 1895.

Krka National park in Croatia near the village of Skradin has a complex water system with waterfalls, rivers, ponds and lakes. © Sari Holopainen

Krka National park in Croatia near the village of Skradin has a complex water system with waterfalls, rivers, ponds and lakes. © Sari Holopainen

However, local people might not be familiar with wetland services connected to their functions. Wetland parks support high biodiversity and several habitat types. Rich biodiversity can even contribute to human health by preventing asthma and allergies. Wetlands also affect nutrient cycling and primary production. These are all very basic ecosystem services that people may not be aware of. According to some studies, local people are poorly aware that wetlands offer water purification. Stormwaters collect nutrients, heavy metals and solids and lead them into water systems. When running through wetlands, nutrients are consumed by the plants and in standing water solid material sinks to the bottom. Due to large constructed areas rain water has only a limited possibility of absorbing into the ground, and stormwater drains can be overloaded during heavy rains. Urban wetlands can mitigate floods and thus prevent costs for society.

A constructed wetland in Nummela village, Finland, offers recreational activities (e.g. picture taken from the birdwatching tower), but it also purifies stormwaters before they reach heavily eutroficated lake Enäjärvi. © Sari Holopainen

A constructed wetland in Nummela village, Finland, offers recreational activities (e.g. picture taken from the birdwatching tower), but it also purifies stormwaters before they reach heavily eutroficated lake Enäjärvi. © Sari Holopainen

Wetlands situated in urban landscapes are globally threatened. Destruction of wetlands leads to different kinds of environmental problems and several ecosystem services are lost; unfortunately it seems that local people are not often familiar with these services. Ongoing destruction is underlined especially in strongly expanding cities in developing countries, while developed countries have in many cases lost their wetlands already long time ago. By including wetlands in the urban landscapes by protecting the remaining wetlands or restoring the lost ones, several ecosystem services for the locals could be quarantined.

Read more:

Franco D. and Luiselli L. 2014. The shared knowledge behind payment for rural ecosystem services: a case study. International Journal of Environmental Studies.

Hettiarachchi M., Morrison T.H. and McAlpine C. 2015. Forty three years of Ramsar and urban wetlands. Global Environmental Change.

Johnson B.B. and Pflugh K.K. 2008. Local Officials’ and Citizens’ Views on Freshwater Wetlands. Society & Natural Resources: An International Journal.

Urban runoff is processed in nature

An urban wetland in Nummela shows the way for new Finnish legislation

The citizens of Nummela in Municipality of Vihti have gathered to admire the new landscape. A verdant wetland has emerged at short notice. The wetland’s purpose is to filter out pollutants and nutrients washed off streets and buildings by stormwater. Since last autumn Finnish cities have been obligated to process urban runoff, which includes stormwater leading away from built areas. Nummela decided to solve this problem with the help of nature. But the urban runoff processes are not the reason why Nummela citizens are tempted to the wetland. The luxuriant wetland is a paradise for diverse fauna and flora, e.g. frogs and newts, and these new neighbours are the reason why enthusiastic outdoor exercisers have congregated at the wetland.

Extreme weather phenomena become more common with climate change

The Nummela wetland is just a trial, originating because of a huge problem looming in the background. In urban areas waters cannot infiltrate into the ground, but cause strong runoffs. Extreme weather phenomena are becoming more and more common with climate change, even in Finland. Torrential rains wash away nutrients and pollutants that have to be processed before they enter rivers, lakes and oceans. This is why the number of urban runoffs has continuously increased during recent years.

Most wetlands have been destroyed

Building small urban wetlands is an efficient way to process urban runoff. It is sadly ironic that development has moved backwards: during the last 100 years two-thirds of Europe’s wetlands have been destroyed. And now we are building them back.

Within cities wetlands filter rainwater that can’t enter the soil through the blacktop. Wetlands retain and process impurities occurring in water. These impurities will sink to the bottom in the wetlands and exit the cycle. From the bottom they can be removed for further processing. As for the nutrients, the wetland vegetation can use them for growth.

Tighten legislation can, at its best, bring beautiful nature for citizens to enjoy. Helsinki, the capital of Finland, has also established four urban wetlands. Their purpose is, in addition to processing urban runoffs, to mitigate flow of stormwater and store snow. Similar urban wetlands will be established in Finland in the future with the aid of new legislation. This way Finns will have new diverse recreational areas within reach.