This is the state of the planet: Living Planet Index 2018 (WWF)

Even though nature provides us with everything our modern society needs, our relationship with her is rather destructive. All the impact that our society has inflicted on Earth has led to a new geological era, which experts have baptised as Anthropocene. The Living Planet Report shows us what is the state of the planet. Do not miss it!

This is not the first time that we make a summary of the Living Planet Report, carried out by the WWF and, with this latest edition, turns 20 years and has the participation of more than 50 experts. Previous reports stressed the remarkable deterioration of Earth’s natural systems: both nature and biodiversity are disappearing at an alarming rate. In addition, it is estimated that on a global scale nature provides services valued at around 110 billion euros per year.

WHAT IS THREATENING BIODIVERSITY?

According to a recent study, the main threats to biodiversity are two: overexploitation and agriculture. In fact, 3 out of 4 species of plants, amphibians, reptiles, birds and mammals extinct since 1500 disappeared due to these two reasons. This is due to the huge growth of consumption worldwide, which explains that the ecological footprint has increased by 190% in the last 50 years.

Overexploitation and agriculture are the main threats for biodiversity (Picture: Ininsa, Creative Commons).

The demand for products derived from ecosystems, linked to their lower capacity to replace them, explains that only 25% of the earth’s surface is completely free of the impacts of human activities. This fraction is expected to be only 10% by 2050.

Soil degradation includes the loss of forest, with the highest rate of deforestation in tropical forests, which harbour the highest levels of biodiversity. Soil degradation has diverse impacts on the species, the quality of the habitats and the functioning of the ecosystems:

• Biodiversity loss.
• Alteration of the biological functions of biodiversity.
• Alteration of habitats and their functions.
• Alteration of the wealth and abundance of the species.

Invasive species are also a common threat, the dispersion of which is associated with trade. Pollution, dams, fires and mining are additional pressures, in addition to the increasing role of global change.

LIVING PLANET INDEX 2018

The Living Planet Index (LPI) is an indicator of the state of global biodiversity and the health of the planet. It is established by calculating the average abundance of about 22,000 populations of more than 4,000 different species of fish, amphibians, reptiles, birds and mammals from around the world.

The global LPI shows that the size of vertebrate populations has decreased by 60% in just over 40 years (between 1970 and 2014).

Vertebrate populations has been reduced a 60% in just over 40 years (Picture: Marc Arenas Camps ©).

If we distribute the analysed species into biogeographic realms, as the lower image shows, we can observe differences in the LPI. The most pronounced population declines occur in the tropics. The Neotropical realm has suffered the most drastic decline: 89% loss respect the year 1970. On the other hand, in the Nearctic and Palearctic the reductions have been much lower: 23 and 31% respectively. The other two realms have intermediate declines, although important: in tropical Africa it is 56% and in the Indo-Pacific 64%. In all the realms, the main threat is the degradation and loss of habitats, but variations are observed.

Biogeographic realms of the LPI (Image: Modified de WWF).

Unlike recent reports, in which the index was separated according to whether the populations were terrestrial, marine or freshwater, in this edition only the freshwater LPI has been calculated. These are the most threatened ecosystems since they are affected by the modification, fragmentation and destruction of habitats; the invasive species; excessive fishing; pollution; forestry practices; diseases and climate change. Analysing 3,358 populations of 880 different species it has been calculated that the freshwater LPI has decreased by 83% since 1970, specially the Neotropical (94% decrease), the Indo-Pacific (82%) and tropical Africa (75%) realms.

AIMING HIGHER: REVERSING THE BIODIVERSITY LOSS CURVE

Despite political agreements for the conservation and sustainable use of biodiversity (Convention on Biological Diversity, COP6, Aichi Targets…), global biodiversity trends continue to decline.

As indicated in the Living Planet Report, “between today and the end of 2020 there is a window of opportunity without equal to shape a positive vision for nature and people.” This is because the Convention on Biological Diversity is in the process of establishing new goals and objectives for the future, adding the Sustainable Development Goals (SDGs). In the case of the SDGs, these refer to:

• SDG 14: Conserve and sustainably use oceans, seas and marine resources for sustainable development.
• SDG 15: Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss.

The authors consider that what is needed are well-defined goals and a set of credible actions to restore the abundance of nature until 2050. To achieve this, the authors recommend following three steps:

1. Specify clearly the objective of biodiversity recovery.
2. Develop a set of measurable and relevant indicators of progress.
3. Agree on a package of actions that together achieve the objective within the required time frame.

CONCLUSION

Looking at the data from the Living Planet Report 2018, it is evident that nature is in retreat: we have lost 60% of the vertebrate populations of the planet, despite the differences between the different areas. In addition, environmental policies are not enough to stop this trend. Therefore, more ambitious policies are needed to stop and recover the nature of the planet in which we live. We have an obligation to live with nature, not against nature. If we do not have more sustainable and respectful habits with the environment, the benefits that nature brings us will be lost and will affect our own survival.

You can read the full report at WWF.

How can you help biodiversity of the cities?

Towns and cities have increasingly become hostile to biodiversity. Fortunately, a few years ago there is a growing interest to make cities more friendly to the native fauna and flora. Discover what you can do for urban biodiversity!

According to SEO BirdLife, 10% of the bird species that live in Spain are housed in urban environments. In fact, some of them, like the sparrow, depend on human presence. In spite of that, these species are in decline.

They also assure that urban birds in Spain have suffered a decrease of over 18% in the last 20 years. For the case of the barn swallow (Hirundo rustica), the loss amounts to 44% of its individuals.

The barn swallow (Hirundo rustica) has lost 44% of its urban population (Picture: Ferran Pestaña, Creative Commons).

BENEFITS OF URBAN BIODIVERSITY FOR PEOPLE

Biodiversity in cities is positive for human beings, beyond the ornamental function, since it offers a set of very important services that improve our quality of life. In fact, the WHO recommends that in cities there are between 10 and 15 m2 of green areas per inhabitant and that the inhabitants have a green area less than 300 m from their house.

In addition to the benefits that nature has for human health and well-being, green areas cushion the temperature (important to reduce the effect of heat islands), purify the air and fix CO2. It is also responsible for the pollination of crops and, in general, to increase the resilience of the environment.

Nature has a positive effect in the human health and wellness.

WHAT CAN WE DO FOR URBAN BIODIVERSITY?

Broadly speaking, to help the biodiversity of cities, we must:

• Provide enough urban green areas in the cities and that they are distributed throughout the area.
• Have urban green spaces connected between them and with the natural environment.
• Generate diversity of habitats.
• Do not plant invasive species.
• Do not use chemical treatments.
• If the green areas are illuminated, make sure it is not annoying for the fauna.

We must bear in mind that, if we have cats at home, we must consider if it is worth doing some of the actions we propose, since our feline friends are great predators and, rather than helping the fauna, we could be harming it.

PLANT TREES, BUSHES AND FLOWERS THAT PROMOTE BIODIVERSITY

Obviously, if we plant native trees or shrubs we will be favouring the biodiversity of our city. If we do not meet this first point and plant exotic invasives, we will be questioning the future of our area. In addition to this fact, we must add other considerations.

The trees or bushes that produce fleshy fruits, such as the olive tree (Olea europea), the strawberry tree (Arbutus unedo) or the lentisk (Pistacia lentiscus), will be able to sustain a part of the diet of some animals. The olive tree also generates holes, which may serve as a nest for some birds. If we look for species that bear fruit in winter, when conditions are more difficult due to the reduction of food, it will also be of great help.

Trees with fleshy fruits promote the presence of food for many animals (Picture: Creative Commons).

Softwood trees, such as poplar (Populus), will allow some birds, such as the Iberian green woodpecker (Picus sharpei), to make holes in its trunk, which will cause that when leaving the nest other species can be installed. We can also leave dead trees standing for the Iberian green woodpecker to make its nest.

Combining deciduous and perennial trees will allow a refuge for wildlife throughout the year.

As for the plants, it is highly recommended to plant indigenous aromatic plants, which will attract a large number of pollinating insects. In the Mediterranean area, you can choose rosemary (Rosmarinus officinalis), lavender (Lavandula stoechas), savory (Satureja montana), thyme (Thymus vulgaris), sage (Salvia officinalis), basil (Ocimum basilicum)…

Indigenous aromatic plants will favour the presence of pollinators (Picture: Kurt Stüber, Creative Commons).

INSTALL NEST BOXES

If there were old trees in the cities (and in the natural areas), it would not be necessary to install nest boxes. The reason is that the old trees have holes, in which the chickadees, the tits, the owls, etc. make a nest. But not only can you install nest boxes for birds, you can also do them for bats, which are effective mosquito eaters.

Installing nest boxes will promote the presence of some birds, such as the Eurasian blue tit (Cyanistes caeruleus) (Picture: Creative Commons)

On the other hand, there are animals that use buildings to breed, such as the peregrine falcon (Falco peregrinus), the kestrels, the crow (Corvus corax), the common swift (Apus apus), the common gecko (Tarentola mauritanica), etc. .

In general, in the Iberian Peninsula there are about 40 species of birds and a dozen mammals that can use nest boxes to breed and rest.

In this Grup Ecologista Xoriguer and VOLCAM Voluntariado Ambiental‘s guide you will find information about how to build yourself a nest box and other tips.

BUILD A INSECT HOTEL OR OTHER STRUCTURES FOR FAUNA

An insect hotel is a construction with a wooden structure that is full of different materials, such as natural cane, stones, tiles, bricks, pineapples, perforated wood or straw, which serve as a hiding, resting and breeding place for various species of insects.

Although you can buy them, we recommend you do it yourself with a little imagination. Collect these materials and about 6-7 wooden pallets and start to build a new home for solitary bees (solitary bees are not aggressive, unlike colonial ones), ladybugs (they will eat the aphid you have in your garden), lacewing, syrphids…

Insect hotel with pallets (Picture: unknown author).

The construction of dry stone spirals with aromatic plants will also favour the presence of fauna, especially reptiles.

In a corner of your garden, you can leave a pile of trunks in the shape of a pyramid. You will see that in a while it will be colonised by mosses, fungi, xylophagous insects, lizards…

VEGETATION MAINTENANCE TASKS

All this is meaningless without sustainable maintenance of green infrastructure. What good is it to plant trees with fleshy fruits if we prune them in full fruition?

Here are some tips:

• Do not prune in the time when the trees are in fruit, concentrate them during the winter.
• Avoid pruning all trees and shrubs the same year.
• Decrease the number of prunings and ask that they be less drastic. So there will be structures that can support large nests.
• Do not remove all the leaves from the ground, since leaf litter allows the development of the invertebrate fauna and incorporates organic matter into the soil.
• Do not use chemical pesticides or phytosanitary products. If you have a pest, use biological control systems against them.

ASK YOUR LOCAL ADMINISTRATION TO JOIN IN THE PROMOTION OF URBAN BIODIVERSITY

Some of these tips will be easy to implement, others will be less. In addition to applying it in your own home, ask your local administration to apply these principles. Together we will make towns and cities more sustainable in which biodiversity can also live!

In addition to the points already mentioned, local administrations can do some other tasks that are within their competence:

• Naturalise artificial lakes. What if, instead of having ponds with crystal clear water, we took advantage of these points to favour the presence of amphibians, reptiles and aquatic vegetation?
• Change lawns for natural meadows. What if instead of having large expanses of green grass, typical of northern Europe (where water is plentiful), we had spaces with different species of native flowers that attracted large numbers of pollinators and birds? Some birds, such as the zitting cisticola or streaked fantail warbler (Cisticola juncidis) or the European stonechat (Saxicola rubicola), make nests in the middle of meadows.
• Reduce the mowing of the lawns (better done at the end of winter) and make differential mowing. What if instead of completely mowing the lawn we did it irregularly to allow the growth of spontaneous vegetation that attracted the invertebrates?
• Plant in the tree clogs. What if instead of having tree clogs full of dog droppings we had them full of flowers that attract the insects that control the plagues of the tree that is planted in it?

Have we encouraged you to apply any of the measures we present? Tell us what you are doing to help urban biodiversity in the comments of this article.

(Cover picture: Kevin Cole, Creative Commons)

How would it be a world without bees?

In recent years, the idea of a world without bees has transcended numerous social and political spheres. The scientific community has been warning about the disappearance of bees during years without any consequence. But now, it has become an issue of major concern, acquiring a media relevance like never before. At the end of 2017, the EU decided to take matters into its own hands to prevent this tragic ending for bees.

Why would it be a problem that bees disappear from Earth? And which measures has the UE take in order to address this problem?

The DDT and Rachel Carson

The use of pesticides has been a common agricultural practice from the very beginning of agriculture. At the beginning, the use of organic chemicals derived from naturals sources, as well as inorganic substances such as sulphur, mercury and arsenical compounds, was very common. However, they eventually stopped being used due to their toxicity (especially, phytotoxicity). The growth in synthetic pesticides accelerated in the mid-twentieth century, especially with the discovery of the effects of DDT, which became one of the most widely used pesticides of all time. DDT became famous due to its generalist insecticidal effects and low toxicity to mammals and plants, being used to eradicate household pests, fumigate gardens and control agricultural pests.

Picture above: cover of a March 1947 brochure on DDT from the U.S. Department of Agriculture (source). Picture below: kids being showered with DDT during a campaing against poliomyelitis, which was believed to be transmitted by a mosquito (source).

DDT resulted to be very effective against insect vectors of deadly diseases such as malaria, yellow fever and typhus, thus becoming even more popular.

However, the overuse of this and other pesticides eventually began to cause severe human and environmental health problems, because some of these products started to contaminate soils, plants and their seeds, and to bioaccumulate within the trophic nets, finally affecting mammals, birds and fishes, among others. The indiscriminate use of pesticides and their effects were denounced by Rachel Carson through her most famous publication, “Silent Spring”, which was distributed in 1962.

Silent Spring, by Rachel Carson (source).

From Carson to the neonicotinoids

Since Carson denounced the abusive use of pesticides, the world has witnessed the birth of many new substances to fight crop pests. Since then, researches have focused on finding less toxic and more selective products in order to minimize their impact on both human and environmental health. Could we say it has been a success?

Yes… and no. Although their use stopped being so indiscriminate and famers started betting on the use of more selective products, there were still some open fronts. Fronts that would remain open until today.

Between 1980 and 1990, Shell and Bayer companies started working on the synthesis of a new assortment of pesticides to face the resistances that some insects have acquired to some of the most widely used substances those days: the neonicotinoids. Neonicotinoids are a class of neuro-active insecticides chemically similar to nicotine; they effect the insect nervous system with a high specificity, while having a very low toxicity to mammals and birds compared to their most famous predecessors (organochlorides, such as the DDT, and carbamates). The most widely used neonicotinoid nowadays (and also one of the most widely used pesticides worldwide) is the imidacloprid.

However, far from getting famous for their effectiveness, the use of neonicotinoids began to get controversial for their supposed relationship with the disappearance of bees.

How do these pesticides affect bees?

For some years now (2006 onwards) the neonicotinoids are in scientists’ spotlight as one of the main suspects of the disappearance of bees. However, it has not been until now that something that scientists had been denouncing for years has finally been assumed: that neonicotinoids cause a greater impact than it was thought.

Dead bees in front of a hive. Public domain.

Unlike other pesticides that remain on plant surfaces, some studies state that neonicotinoids are taken up throughout their tissues, thus being accumulated in their roots, leaves, flowers, pollen and nectar. Also, that nearby fields are polluted with the dust created when treated seeds are planted and that plants derived from these seeds will accumulate a major amount of pesticide than sprayed plants (as it is explained in this publication of Nature). This causes bees (as well as other pollinating insects) to be exposed to high levels of pesticides, both in the crops themselves and in the surrounding foraging areas. These same studies have revealed with less support that these products may persist and accumulate in soils, which may affect future generations of crops.

Some of the negative effects on bees that have been related to neonicotinoids are:

• Altered immune system, reduced overwintering success and reproduction in both honeybees and wild bees (according to this recent study published in Science).
• Risk of disorientation in bees when looking for food (foraging habits) in both honeybees and wild bees, as well as communication disruption in colonial bees.
• Enhanced negative effects by the interaction with other pesticides.
• Contribution to the CCD (Colony Collapse Disorder). This phenomenon is characterized by the massive disappearance of worker bees from a colony, which leave behind the queen along with food, its larvae and some bees that take care of them. This phenomenon has been recorded numerous times throughout history; the last one occurred in the USA in 2006, when a large number of honey bee colonies (Apis mellifera) began to collapse (until 2013, about 10 million hives have disappeared, almost 2 times more than what is considered normal). The CCD is a multifactorial phenomenon, in which the action of pesticides seems to be only one of a long list of possible triggers.

In addition to the effects of neonicotinoids, other important causes must be taken into account: climate change, less food sources and changes in soil uses.

What would happen if bees disappear?

Colonial bees (like honeybees) are the most famous among bees. However, they only represent a mere portion within the great diversity of known bees, most of which have solitary life habits and build their nests inside small cavities. The ecological importance of solitary bees is equal to or greater than that of honey bees, but effects that neonicotinoids have on them are still poorly studied. Together, bees are among the most efficient pollinating organisms.

Solitary bee entering in its nest. Public domain.

According to this study carried out in German territory and published in POLS One at the end of 2017, a large part of flying insect diversity (including numerous pollinators) and up to 75% of their biomass have decreased in the last three decades due to the interaction of several factors. And if that was not enough, the authors say that these numbers can probably be extrapolated to other parts of the world.

What would happen if both colonial and solitary bees disappear?

• Disappearance of crops. The production of many crops, such as fruit trees, nuts, spices and some oils, depends entirely on pollinators, especially on bees.
• Decrease in the diversity and biomass of wild plants. Up to 80% of wild plants depend on insect pollination to reproduce, as it happens with many aromatic plants. A decrease in the vegetal surface would lead to serious problems of erosion and desertification.
• Less recycling of soil nutrients. With the disappearance of the plants, the washing and deposition of soil nutrients would go down.
• Less biological pest control. Some solitary bees are parasitoids of other solitary bees and other groups of insects (natural enemies); their absence could trigger the recurrence of certain pests.
• Negative effects on higher trophic levels. The disappearance of bees could cause a decrease in the diversity and biomass of some birds that feed on pollinators.
• Disappearance of bee-derived products, such as honey or wax.

The UE bans the use of neonicotinoids

Facing this reality, several governments have tried to limit the use of pesticides as a part of the measures to stop the decline of bee populations and the resulting economic losses. To give some examples, since 2006 the biomass of honey bees has decreased by 40% in the US, 25% in Europe since 1985 and 45% in the United Kingdom since 2010, according to data published by Greenpeace.

To date, the more restrictive measures limited the use of neonicotinoids in certain situations or seasons. But at the beginning of 2018, the EU, after preparing a detailed report based on more than 1,500 scientific studies carried out by the EFSA (European Food Safety Authority), decided to definitively ban the use of the three most used neonicotinoids in a maximum period of 6 months in all its member states after demonstrating that they are harmful for bees: imidacloprid, clothianidin and thiamethoxam.

Will the objectives of this report be accomplished? We will have to wait …

.           .           .

Although slowly, the fight against the abusive use of pesticides is paying off. However, we will have to see if the gap left by some products is filled with other substances or if governments commit to adopt more environment friendly agricultural models.

Main picture obtained from [link].

Dinosaurs from the North Pole: Live at Prince Creek

When we think about dinosaurs, we probably imagine them walking through a dense, tropical jungle or wandering in a warm, foggy swamp. But as a matter of fact, some dinosaur species lived in very high latitudes, as the ones found in the Prince Creek formation. This Alaskan geologic formation is one of the most important sources of arctic dinosaurs, as many fossils have been found in it. In this entry, we’ll describe some of these dinosaurs from the North Pole, and we’ll explain some of the difficulties they had to endure in order to survive in the northernmost point of the planet.

ALASKA 75 MILLION YEARS AGO

The Prince Creek formation is situated in the north of Alaska and dates from around 80-60 million years ago, at the end of the Cretaceous, the last period of the Mesozoic. At that time, North America was divided by the Western Interior Seaway; the eastern continent or Appalachia, and the western continent or Laramidia, north of which the Prince Creek formation was deposited.

Map of North America at the end of the Cretaceous period, with the Prince Creek formation marked in red, from the article New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism.

At the end of the Cretaceous period, the Prince Creek formation was further north than it is today. Yet, at that time the Earth was going through a greenhouse effect phase, so the climate was a little warmer than it is today. It is thought that the mean annual temperature at Prince Creek was about 5°C, with summer maximums at about 18-20°C. Still, the difference in temperature between summer and winter would have been quite remarkable (currently, at the same latitude, it’s about 56°C).

Even if temperatures were not as low as the ones of present-day Alaska, the dinosaurs of Prince Creek had to endure long, dark winter months. Yet, the slightly higher temperatures and the proximity to the sea, produced a higher diversity of plant species. Observing the fossilized flora, we know that the landscape was that of a polar woodland, with angiosperm-dominated forests and a large number of fern, moss and fungus species, with some areas of seasonally-flooded grasslands.

Drawing by Julio Lacerda of Prince Creek’s landscape and wildlife.

As for the fauna, palaeontologists were surprised at the great number of big animals found. The fact that dinosaurs were found in such high latitudes is what makes us think that these were endotherm animals that generated their own body heat. Also in Prince Creek, there aren’t any fossils of other ectotherm reptiles like turtles, crocodiles or snakes, which are usually found in other United States deposits of the same period. Currently, dinosaurs are thought to be neither endotherm nor ectotherm, but mesotherm animals, which generated body heat metabolically, but were unable to control its temperature or keep it stable.

TOUGH HERBIVORES

The relatively abundant vegetation, allowed the presence of a great diversity of plant-eating dinosaurs in such high latitudes. While the smaller herbivores had little trouble because of their low energetic requirements, the larger herbivores probably had more difficulties in order to find enough food, especially during the harsh winter months. The dinosaur fossil found at the highest latitude is Ugrunaaluk (literally “ancient grazer” in Inupiaq language from northern Alaska) a hadrosaurid or “duck-billed dinosaur”. This ornithopod measured up to 10 metres long and weighed around 3 tonnes, making it one of the largest animals in Prince Creek.

Reconstruction by James Havens of a herd of Ugrunaaluk kuukpikensis, moving under the polar lights.

Ugrunaaluk were herbivorous animals that lived in groups. Even if many author think that these animals performed long migrations like today’s birds and mammals in order to avoid the lack of food during the winter, some others argue that young Ugrunaaluk (which had a less active metabolism than current endotherms) would had been unable to endure such long journeys. Ugrunaaluk probably moved to areas were the vegetation better tolerated the severity of winter, even if it’s thought that these great herbivores survived during the dark winters feeding on bark, ferns and probably aquatic vegetation during the coldest months.

The other great Prince Creek plant-eater was Pachyrhinosaurus (literally “thick-nosed lizard”) a ceratopsid widely-distributed through the United States, with a large protuberance on its nose which may have been used as a weapon during intraspecific combats, and a pair of laterally-facing horns on the top of its frill. Pachyrhinosaurus was the largest animal of Prince Creek, measuring up to 8 metres long and weighing up to 4 tonnes. It is possible that it used its nasal protuberance to shovel through the snow to reach the plants buried under it, similar to today’s bisons.

Reconstruction of a pair of Pachyrhinosaurus perotorum by James Havens.

All the animals of Prince Creek had arduous lives. Almost all the fossils of both Ugrunaaluk and Pachyrhinosaurus, indicate that these species matured quickly and died young. Observing the growth of the different bones that have been found, it is thought that these dinosaurs rarely lived for over 20 years of age, probably due to the harsh conditions of their habitat but also to the presence of predators.

PREDATORS LARGE AND SMALL

The largest predator of the region was Nanuqsaurus (“polar bear lizard”, from Inupiaq language), a tyrannosaurid. This animal had a highly developed sense of smell which allowed it to detect their prey or animal carcasses in low light during the polar winter. Also, although there is no evidence, it was probably covered in feathers which would have protected it from the cold, as many closely-related theropods presented feathers to some extent.

Reconstruction of Nanuqsaurus hoglundi by Tom Parker.

What’s more surprising about Nanuqsaurus is its size, much smaller than that of its relatives. While other tyrannosaurids from the same time measured between 10 or 12 metres long and weighed up to 9 tonnes, Nanuqsaurus was more of a pygmy tyrannosaur, with an estimated length of 6 metres and a weight of 800 kg. This diminutive size was probably caused by the fact that it lived in an environment where food availability varied through the seasons. Apart from the fact that their prey’s population densities probably weren’t very high, during winter months many herbivores would migrate to other areas.

By contrast, there was another theropod that presented the opposite adaptation. Troodon (“wounding tooth”) was a relatively small dinosaur, about 2.9 metres long and 50 kg of weight. This is a pretty abundant dinosaur in many North American deposits. Troodon was a highly active carnivorous animal, with a good binocular vision and it’s also believed to be one of the most intelligent Mesozoic dinosaurs.

Reconstruction of two Troodon inequalis playing in the snow by Midiaou.

While Nanuqsaurus was smaller by the lack of abundant prey, Troodon specimens found at Prince Creek were characterized by their bigger size, compared with the ones from other deposits. This is what is called the Bergmann’s Rule, according to which the populations of a species that live in colder climates tend to be larger than the populations living in warmer climates, as this way they lose less body heat. Also, the larger eyes of Prince Creek’s Troodon, would give them advantage hunting during the long winter nights.

Image from the article A Diminutive New Tyrannosaur from the Top of the World, in which we can see the size of Nanuqsaurus (A) compared with some other tyrannosaurids (B, C, D and E) and two Troodon specimens (F and G) from different latitudes.

As you can see, dinosaurs not only thrived in warm and tropical environments. Even if their populations weren’t very large and their living conditions were harsher, these dinosaurs were able to adapt and survive in the polar forests of Prince Creek, and many of them surely gazed at the spectacular northern lights of 75 million years ago.

Assembly of the different dinosaur species from the Prince Creek formation by James Kuether.

REFERENCES

The following sources have been consulted during the elaboration of this entry:

• Susana Salazar Jaramillo (2014). Paleoclimate and paleoenvironment of the Prince Creek and Cantwell formations, Alaska: terrestrial evidence of middle Maastrichtian greenhouse event. Thesis.
• Live Science. Polar Dinosaurs Endured Cold Dark Winters.
• The Strange Lives of Polar Dinosaurs.
• North Pole Dinosaurs Lived Short, Hard Lives: Discovery News.
• Gangloff, Fiorillo & Norton (2005). The first Pachycephalosaurine (Dinosauria) from the Paleo-Arctic of Alaska and its Paleogeographic implications. Journal of Paleontology. Vol. 79. Pp: 997-1001.
• Mori, Druckenmiller & Erickson (2016). A New Hadrosaurid from the Prince Creek Formation (Lower Maastrichtian) of Northern Alaska. Acta Palaeontologica Polonica. Vol. 61. Pp: 15-32.
• Fiorillo & Tykoski (2014). A Diminutive New Tyrannosaur from the Top of the World. PLoS ONE 9(3).
• Cover Image by Julio Lacerda.

The living space of organisms

We all have our own living space, the place where we feel comfortable, like we were at home. We also have our routines, habits and that list of preferences that make us unique. Each of us, ultimately, have our own ecological niche, an extensive concept for each species that share the Earth with us. From it comes an important ecological processes such as competition or speciation, a key concepts for understanding the assembly and dynamics of natural ecosystems.

INTRODUCTION

When you are asked how you would describe close people, the first thing that comes to your mind is their way of being when you’re with them and what they loves to do. We know what is the first thing they always ask in a restaurant, what annoys them, what sites they like to frequent, what they like to do when they have free time and even how they behave when they like someone. If we have also lived with them, we could guess almost their daily routine since they wake up until they go to bed. Although we do not always have the same behaviour, there are many traits, hobbies and routines that characterize and differentiate us. Each of us have our comfort zone, our hobbies, food preferences and people with whom we love spending our free time.

The dietary preferences of each of us and our routines and hobbies serve as a comparison to illustrate the diversity of ecological niches in the natural world. Source: Flickr, George Redgrave.

THE ECOLOGICAL NICHE OF A SPECIES

This “living space” that all of us have and in which we feel identified, is also comparable to the ecological niche of the organisms. The ecological niche of a species is a concept that always has been presented us as the “occupation”, “profession” or “work” that an organism carries up in the place where it lives (Wikipedia or CONICET), but the definition includes more than that. Hutchinson (1957) defined it as: ” n-dimensional hypervolume, where the dimensions are environmental conditions and resources, that define the requirements of a species to persist over time.” Despite the confusing definition, it is interested to point out the term “n-dimensional” as the ecological niche is based on this idea. An ecological niche is nothing more than all those multidimensional species requirements. In other words, the ecological niche of a species would be everything that involve the species and make it to prosper and survive where it is. Refers, ultimately, to all those variables that affect them in their daily lives, both biological variables -the contact with other species- and the physical and chemical ones-the climate and the habitat where they live-. An ecological niche of a species would be the spectrum of food it eats or can consume, the time of the day in which it is active to perform its functions, the time of the year and the way it carries out the reproduction, the predators and preys, the habitat it tolerates and all those physical and chemical factors that allow this species to remain viable.

These 5 species of warblers of North America seem to occupy the same habitat (the fir), but actually not. The truth is that each warbler occupies a different position in the tree. Source: Biology forums.

To give an illustrative example, let us place ourselves in the African savannah. The main grazing ungulates and those which perform mass migrations are compound by zebras, wildebeest and Thomson’s gazelles. At first glance, you might think that their ecological niche is very similar: same habitat, same routine, same predators and same food. The same food? Absolutely not. During migration, zebras go ahead, devouring tall grass, which is the worst quality. They are followed by wildebeest, which eat what remains standing, and these are followed by Thomson gazelle, which eat the high-quality grass, which is starting to grow again.

Although at first glance it may seem that feed on the same food, each species focuses on a different part of the plant. Source: Abierto por vacaciones.

CAN TWO SPECIES LIVE TOGETHER WITH THE SAME NICHE IN THE SAME PLACE?

The competitive exclusion principle, proposed by Gause (1934), states that two species occupying the same niche can not coexist in the long term as they come into competition for resources. Thus, in a competitive process for the same ecological niche, there is always a winner and a loser. In the end, one of the competitors is imposed by another, and then two things can happen: the extinction of the loser one (image A) or a traits displacement in order to occupy another niche (image B). In fact, the competitive exclusion principle is behind the current problems with invasive species. Invasive species niche is very similar to native species niche and, when they converge in the same habitat, the invasive species end up displacing native species, as they are better ecological competitors. It also often happens, of course, the opposite: the exotic species is worse than its counterpart and the competitor fails to thrive in the new environment.

Image A | This study was conducted in order to observe the effect of competitive exclusion in two species of protists. Both species occupy almost identical ecological niches, but they are not living together in nature. The density of one falls sharply when they are forced to share the same space, until it eventually disappears. This same process occurs with invasive species. Source: Jocie Broth.

Image B | When the 3 species of Darwin’s finches (in different colors) coexist on the same island, a trait displacement occurs by competitive exclusion. Individuals from the ends tend to have very similar bill depths to those of the other species, resulting in a niche overlap and subsequent competition. The final boundaries are established thanks to this process. Source: Nature.

THE FUNCTIONAL EQUIVALENCE

We have seen that to share ecological niche is synonymous of having conflict between species. However, there is a situation in which problem do not take place. The hypothesis of functional equivalence proposed by Hubbell proclaims that if the niches are identical and the species life parameters (fertility, mortality, dispersion) are also the same, none of them has a competitive advantage over the other, and the battle ends in tables. This fact seems to occur only in a very stable ecosystem in a Panama rainforest island (Barro Colorado). Different species of trees, as having almost identical parameters of life, do not compete between them and are distributed randomly, as if the individuals of different species belong to the same species. Furthermore, it seems that speciation in this kind of rainforest could also occur by chance, which would have caused the high density of species that harbor these forests.

Tropical forests have a tree species density unique in the world. One hectare of tropical forest may contain up to 650 tree species, more than the number of tree species present in both Canada and continental US. Will Hubbell’s functional equivalence theory be behind the explanation for this curious fact? Source: Flickr, Jo.

NEW NICHES, NEW SPECIES

Speciation, or the creation of new species, usually occurs when new ecological niches are created or the existing become unoccupied. In both cases, to occupy a new ecological niche imply a gradual differentiation from the initial population to become a genetically distinct species. As an example of formation of new ecological niches we have the case of the emergence of angiosperms. Their booming opened many new possibilities, thanks both to increasing diversity of seeds and fruits (which, in turn, increased the number of specialized species) and the emergence of complex flowers, which allowed the explosion of many pollinators (facilitating the emergence of new insectivores). As an example of unoccupied niche, there is the famous case of the extinction of non-avian dinosaurs. Dinosaurs dominated a lot of niches, from land to air ecosystems, and even the aquatic environment. Those empty niches was occupied by many mammals, thanks to their high fertility and plasticity (flexibility to adapt into different habitats). That eventually led large ratios of speciation in a short time, what is known as adaptive radiation.

This is Eomaia scansoria, an extinct species of mammals that lived at the same time as the dinosaurs. The extinction of the dinosaurs opened up a wide range of possibilities to mammals, which, although they were expanding, remained in the background. Their great plasticity led them to colonize many habitats, by occupying the free ecological niches left by the dinosaurs. Source: Wikipedia.

ASSEMBLY OF COMMUNITIES

As we have seen, the ecological niche is behind fundamental ecological and evolutionary processes. All living communities today have been formed thanks to the niches of different species. Through competition, species niches were overlaping, and the communities were assembled like a puzzle. When a piece disappears, another takes its place, playing the role that the other had in the community. However, knowing the whole ecological niche of a species is arduous and, in most cases, impossible. As in human relationships, an exhaustive knowledge of everything that influences the life of a species (or the living space of a person) is of great importance in order to ensure their long-term preservation.

REFERENCES

• Hutchinson, G.E. 1957b. Concluding remarks-Cold Spring Harbor Symposia on Quantitative Biology. 22:415-427. Reprinted in: Classics in Theoretical Biology. Bull. of Math. Biol. 53:193-213
• Herrera CM, Pellmyr O (2002) Plant-Animal Interactions. An Evolutionary Approach. Blakwell Science Ltd. Osney Mead, Oxford, UK.
• Cfr Washington
  
• EfeFuturo.com 
• El País
•  Hubbell S.P. (2005). Neutral theory in community ecology and the hypothesis of functional equivalence. Functional Ecology 19, 166–172.
• Notes from ecology lessons at UAB Masters program.
• Cover image: Taringa.net
  

Migration in danger! The disappearance of the monarch butterfly

Generally, we tend to think of migration as an event exclusively linked to complex organisms (like mammals or birds). But there are always exceptions: the North American populations of the monarch butterfly (Danaus plexippus) cover a distance of almost 5000km (more than some complex animals!) in order to reach their hibernation areas, where there can be concentrated thousands of specimens during the winter. Unfortunately, the migration phenomenon depend on many factors that are being damaged by anthropogenic pressure nowadays, so that the future of these populations and also their migration are in danger.

Throughout this article, you will learn some of the most curious biology traits of these organisms, the main causes that could be endangering their populations and the consequences that this would entail.

INTRODUCTION

The monarch butterfly (Danaus plexippus) is a butterfly of the Nymphalidae family. It’s also probably one the most well-known butterflies of North America due to its long migration, that their specimens perform from the north of EEUU and Canada to California coast and Mexico, covering a distance of almost 5000km to reach their hibernation areas. It’s, by far, the insect that performs the widest and large migration of all.

Specimen of monarch butterfly (Danaus plexippus) with its typical color pattern: white, black and orange (Picture by Peter Miller on Flickr, Creative Commons).

Although the North American populations of this species are the most known worldwide due to their migration pattern, there are also monarch butterflies in some Atlantic islands (Canary islands, Azores and Madeira), and sometimes also as eventual migrators that reach the coasts of Western Europe (United Kingdom and Spain). Moreover, they were introduced in New Zealand and Australia during the XIX century.

LIFE CYCLE

The life cycle of this species is very unique. First of all, they’re considered specialist butterflies: they lay their eggs exclusively over plants of the Asclepias genus (also known as milkweeds), and their newborn caterpillars (which are black, white and yellow striped) feed only on these plants. This is a very interesting fact, because the plants of this genus contain cardiac glycosides that are progressively assimilated by the caterpillar tissues, which let them to acquire a disgusting taste that prevents them to be predated. This taste will last during their adult phase.

Caterpillar of a monarch butterfly (Picture by Lisa Brown on Flickr, Creative Commons).

Once completed the larva phase, the metamorphosis take place so that the caterpillars become adult butterflies colored in black, white and orange. Both caterpillar and butterfly color patterns carry out a communicative function: it’s a mechanism to warn other animal of their toxicity, fact which is known as aposematic mimicry (this phenomenon is very frequent in a lot of group of animals, even in mammals).

Phases of the metamorphosis of the monarch butterfly (Picture by Steve Greer Photography).

The adult phase also has some particularities: during the mating season (April-August) some generations of adults are generated, and each of them has a life expectancy of a few weeks, more or less. Then, an awesome event takes place: the butterflies of the generation born at the end of August (when temperatures get low and days became shorter) stops the maturing process of their reproductive organs (phenomenon known as diapause) so they can spend their energy on enlarging their life expectancy to 9 months. This generation is known as “Methuselah generation” due to its longevity.

The increase of their longevity allows this generation to cover the long distance required to reach the hibernation areas during the autumn (Mexico and California coast) and then to come back to the north of America at the end of the winter.

Hundreds of monarch butterflies flying over the place called ‘El Santuario ‘El Rosario” (Mexico) (Picture by Luna sin estrellas on Flickr, Creative Commons).

A ROUND TRIP: THE GREAT MIGRATION

Although the monarch butterfly isn’t only located in North America, there is no evidence nowadays showing that the other populations of monarch butterflies do such a long migration. It’s believed that the fact that only these populations of butterflies go on a trip this long is due to the wide spreading of plants of the Asclepias genus over all North America that took place in the past. Scientists suggest this event allowed the monarch butterflies to spread progressively to the south.

WHICH PLACES DO THE BUTTERFLIES VISIT?

A migration is always a complex process. In this case, the migration to the south is divided into two simultaneous migrations:

• The east migration: this trip is made by those butterflies that fly from the east of the Rocky Mountains, South of Canada and a big part of USA to the central part of Mexico (90% of all the monarch butterflies located in North America go on this trip).
• The west migration: this trip is made by those butterflies that fly from the west of the Rocky Mountains, South of Canada and a little part of USA to the California coast (10% of all the monarch butterflies located in North America go on this trip).

Migratory patterns of the monarch butterfly in North America (round trip) (Sources: Monarchwatch.org y Monarch Alert).

Once in the winter habitats, the butterflies plunge into a lethargic state until the next spring, when they become sexually active and start mating before heading again to the north.

It’s a very surprising event seeing all the butterflies sleeping together and covering all the plants and trees of the winter habitats!

Thousands of butterflies gather over the vegetation (Picture by Carlos Adampol Galindo on Flickr, Creative Commons).

PROTECTED AREAS

There exists a lot of protected areas all over the places where the butterflies go through.

One of the most important protected areas is the Monarch Butterfly Biosphere Reserve (Mexico City), which is considered a World Heritage Site by the UNESCO since 2008.

Monarch Butterfly Biosphere Reserve (Picture by Michelle Tribe on Flickr, Creative Commons).

And why are these butterflies so protected? Besides the fact that their migration pattern is considered an incredible phenomenon, they are pollinators that contribute to the pollination of the wild flora and also of the crops of North America.

THE ‘QUEEN’ IS IN DANGER!

Although there exists a huge effort to protect them, the migratory phenomenon of the North American monarch butterflies is in danger nowadays due to the anthropic pressure, which could also put their populations at risk in the future.

According to the data generated by the WWF, the surface of the winter habitats occupied by these butterflies has decreased 94% in 10 years, going from 27,48 acres occupied in 2003 to only 1,65 acres in 2013. This is the lower value registered in the last 20 years.

Decresing of the surface occupied by the monarch butterflies in the winter habitats (Data form WWF website).

Even though the surface occupied by these organisms has been fluctuating over the years as a part of a natural process, this pronounced decreasing that has taken place in only a few years suggests that butterflies are stopping their annual migrations to the south.

Total occupied area by the butterflies in their winter habitats since 1993 to 2013 (WWF-Telcel-CONANP).

This recession has also been registered in other species of butterflies at different emplacements all over the world, so there must exist some kind of factor in common with the ones affecting the North American monarch butterfly populations.

WHAT COULD BE THE MAIN CAUSES OF THIS RECESSION?

According to the WWF, the main causes that could being putting in danger the migration process of the monarch butterflies are:

• The reduction of the surface occupied by plants of the Asclepias genus: as we said above, the caterpillars feed exclusively on these plants. But the use of certain herbicides and the changes on the rain patterns could being limiting their dispersal over a big part of North America.
• Deforestation: cutting down trees massively and the subsequent desertization could being reducing their winter habitats.
• Extreme climate: the global change, which entails changes in temperature and rain patterns, could being putting at risk the survival of adult butterflies, preventing them to reach the longevity required to carry out complete migrations.

WHICH EFFORTS ARE MADE TO PROTECT THESE POPULATIONS?

As I said above, monarch butterflies are an essential part of the pollination net of North America and also iconic insects, so there exists a big interest on protecting them.

Nowadays, most of the protected areas of North America are making a big effort to improve the quality of their habitats. Among them, the Monarch Butterfly Biosphere Reserve (Mexico) along with the WWF are trying to restore the woods where butterflies hibernate and also promoting a sustainable tourism (enter this link to see more information).

 .            .            .

The case of the monarch butterfly is only one of a huge list of animals in danger. Nowadays, a lot of animals with complex migration patterns and wide spreading areas are suffering similar pressures, mostly of them with an anthropogenic origin. There’s still so much work to do, and it depends on all of us.

REFERENCES

• WWF – Monarch Butterfly
• Soymonarca.mx
• Monarch Butterfly information
• Monarch Butterfly Fundation
• Scientific American – “Monarch butterflies Could Gain Endangered Species Protection”
• CBC News – “Why the monarch butterfly migration may be endangered”

• National Geographic – “Migrating Monarch Butterflies in “Grave Danger,” Hit New Low“

Main picture by Carlos Adampol Galindo on Flickr.

What do insects tell us about the health of our rivers?

Nowadays, concern about the health of inland waters (rivers, lakes, etc.) is growing, mainly due to increased use (and abuse) of these for human consumption. A few years ago, an expansion of the use of biotic indices took place, which allow us to determine the health of aquatic ecosystems; these indices usually use data such as presence, absence or/and abundance of different organisms known as ‘bioindicators’, that is, species that can be used to monitor the health of an environment or ecosystem. Among these organisms, there are a lot of arthropods.

Along this article, I will briefly explain what bioindicators are, the main role of arthropods as bioindicators and also introduce some of the most used bioindication indices to monitor the quality of riverine ecosystems in the Iberian Peninsula.

What is a bioindicator?

The term ‘bioindicator’ is used to refer to those biological processes, species or/and communities of organisms which can be used to assess the quality of an ecosystem and also how this ecosystem evolves over time, which is especially useful when changes take place due to anthropogenic disturbances, such as pollution.

Thus, in accordance with the above, a bioindicator can be:

• A particular species, whose presence/absence or abundance rate informs us of the state of health of a studied ecosystem, or
• A population or a community composed of various organisms which varies functionally or structurally according to the conditions of  environment.

Example: Lecanora conizaeoides lichen is highly resistant to pollution. Its presence on the studied ecosystem, coupled with the disappearance of another lichens, is indicative of high air pollution.

Lecanora conizaeoides (Picture by James Lindsey).

What do we consider a ‘good bioindicator’?

Do all the organisms have the necessary traits to become bioindicator subjects? The answer is no. Even though there is not a bioindicator prototype (because all depends on the studied ecosystem), we can resume here some of the traits that scientists take into account to select good bioindicator organisms:

• They have to respond to disturbances that take place on their ecosystem to a greater or lesser degree. This response should be comparable to that emitted by the rest of the organisms of the same species, and this response also has to be well correlated with the studied environment disturbances.
• Their response have to be representative of all the community or population.
• They must be native of the studied ecosystem and also be ubiquitous (that is, to be present in almost all ecosystems of the same or similar characteristics).
• They have to be abundant (rare species aren’t optimum subjects).
• They must be relatively stable to moderate climate changes (i.e. a storm or a natural temperature change does not affect them more than normal).
• They should be easy to detect and, as possible, they have to be sedentary.
• They have to be well studied, both from an ecological point of view as taxonomic (to know, therefore, their tolerance to environmental disturbances).
• Finally, they should be easy to manipulate and monitor in the laboratory.

The use of bioindicators will be optimized if we use entire communities or populations instead of using a single or a couple species, because this allows us to cover a wide interval of environmental tolerances: from organisms with a narrow tolerance range (that is, stenotopic) and sensitive to pollution, to very tolerant organisms that can survive in very polluted environments.

Thus, we will be able to know if an ecosystem is highly altered if we find only a very tolerant species and none of the considered sensitive species.

Bioindicator animals from inland waters

Nowadays, scientists use a lot of animals as bioindicators: from microorganism and microinvertebrates to terrestrial and aquatic vertebrates (micromammals, birds, fishes, etc.). In inland waters, and especially in the context of studies of riverine water quality, scientists mostly use aquatic macroinvertebrates to assess the quality of these ecosystems. Next, let’s see what a macroinvertebrate is.

What are macroinvertebrates?

The term ‘macroinvertebrate’ does not correspond to any taxonomic classification, but with an artificial concept that includes different aquatic invertebrate organisms.

Generally, is said that macroinvertebrates are organisms that can be trapped by a net with holes about 250μm.

Collecting macroinvertebrates by using a kick seine (Picture by USFWS/Southeast , Creative Commons).

Macroinvertebrates are mainly benthic, that is, animals that inhabit the substrate of aquatic ecosystems at least during some stage of their life cycle (although there are some that swim freely in water column or on its surface).

We can find a lot of macroinvertebrate groups in rivers and lakes, which can be classified in two main groups:

Picture sources: (1) Luis Silva Margareto ©, (2) DPDx Image Library, (3) Oakley Originals, Creative Commons, (4) Ryan Hodnett, Creative Commons, (5) Will Thomas, Creative Commons, (6) Duncan Hull, Creative Commons.

Among these groups, there are both tolerant organisms to environment distrubances (i.e. leeches) and sensitive organisms (i.e. a lot of larvae insects).

Most inland aquatic macroinvertebrates (≃80%) are arthropods (of which I will discuss in the next section), among which there are many insects and, especially, their larvae (which are generally benthic), whose study and observation play an essential role on calculating indices of water quality.

Importance of insects in bioindication

As I’ve said above, about 80% of macroinvertebrates of inland waters are arthropods and, mostly, different orders of insects in its larval or nymphal form. Let’s see some of the most common groups we can find in rivers and lakes:

Trichoptera (or caddisflies)

They are insects closely related to the Lepidoptera order (butterflies and moths). Their aquatic nymphs can build a shelter around their bodies made of substrate materials. We can distinguish them from other aquatic insect larvae because they have a couple of anal filaments provided with strong hoofs. They usually inhabit clear and clean waters with a lot of currents.

Trichoptera nymph (inside its shelter, left) and adult (right). Picture of the nymph by Matt Reinbold (Creative Commons) and picture of the adult by Donald Hobern (Creative Commons).

Ephemeroptera (or mayflies)

One of the most ancient orders of flying insects. Their aquatic nymphs, which usually inhabit rivers, are characterized for having three long anal filaments. Adults, which fly over the water surface, are very fragile and have a short life cycle in comparison with nymphs (the name Ephemeroptera is derived from Greek ‘ephemera’ meaning sort-lived, and ‘ptera’ meaning wings).

Ephemeroptera nymph (left) and adult (right). Picture of the nymph by Keisotyo (Creative Commons) and picture of the adult by Mick Talbot (Creative Commons).

Plecoptera (or stoneflies)

Flying insects very similar to Ephemeroptera order. Like these, they have anal filaments, but they differentiate from them because they have two apical hooks in each leg. They usually inhabit lakes and streams.

Plecoptera nymph (left) and adult (right). Picture of the nymph by Böhringer (Creative Commons) and picture of the adult by gailhampshire (Creative Commons).

Other groups of insects with aquatic larvae or nymphs

Among the most common insects inhabiting rivers and lakes we can also find species of Odonata order (dragonflies and damselflies), Coleoptera (beetles), Diptera (mosquitoes and flies), etc.

Among all the organisms mentioned above, there are very tolerant species to pollution (i.e. some Diptera larvae; this is the case of some species of Chironomidae family, which are very tolerant to organic and inorganic pollution due to the presence of heavy metals in their environment) and also very sensitive species (i.e. some species of Trichoptera order).

Depending on their tolerance to environment disturbances, scientists group these organisms (plus the rest of macroinvertebrates) into different categories that are assigned a value. This values, at the end, allow us to calculate water quality indices.

Biotic indices for riverine waters

The different pollution tolerance degrees among macroinvertebrates of a community allow us to classify them and to assign them a qualitative value (the bigger the number is, more sensitive are organisms to pollution). Thanks to these values, we can calculate different biotic indices, which are no more than qualitative values assigned to a community in order to classify it according to its quality: the greater the value is, better is the water quality.

One of the most used indices on the assessment of ecological state of rivers from the Iberian Peninsula is the IBMWP index (Iberian Bio-Monitoring Working Party), an adaptation by Alba Tercedor (1988) of the British index BMWP. In rough outlines, the greater the value is, better is the water quality. On this website you will find more details about this index, and also the pre-established values assigned to each macroinvertebrate (available in Spanish only).

In additions, there is also used the IASPT index, a complementary index which is the result of divide the IBMWP value by the number of identified taxa. This index give us information about the dominant community in the studied location. You can see more details on this website (available in Spanish only).

.      .      .

As you probably have seen while reading of this article, macroinvertebrates, and insects especially, play an important role in the study of inland water quality. Furthermore, their presence or absence is extremely important for the rest of the organisms of their ecosystem, because of what we must become aware of the problems deriving from the reduction of their number or diversity.

REFERENCES

• Bioindicadors com a detectors de la contaminació ambiental. Diari Apícola Ecolluita (Associació Col·lectiu Abellaire).
• Bioindicadors. GESNA (Estudis Ambientals S.L.).
• Estudio de determinación de índices bióticos en 87 puntos de los ríos de Navarra (Informe Final, 2005). Ekolur, Asesoría Ambiental.
• Holt, E. A. & Miller, S. W. (2010) Bioindicators: Using Organisms to Measure Environmental Impacts. Nature Education Knowledge 3(10):8.
• MEDPACS (MEDiterranian Predictions And Classifictions System).
• Prat N., Ríos B., Acosta R., Rieradevall M. (2009). Los macroinvertebrados como indicadores de calidad de las aguas.
• Protocolo de cálculo del índice IBMWP. Ministerio de Agricultura, Alimentación y Medio Ambiente (Gobierno de España).
• http://www.cricyt.edu.ar/enciclopedia/terminos/Bioindic.htm
• https://ilbca.wordpress.com/bioindicadores/
• http://xtec.cat/cda-delta/pdf/rv_invertebrats.pdf

Head photography by U.S. Fish and Wildlife Service Southeast Region.