Foreseeable effects of hydropower intensification on Amazonian biodiversity

Primarily driven by increasing electricity demands, the intensity of dam-building within the last century has left two-thirds of the planet's large rivers fragmented by dams.  In addition to the already existing 191 dams, the nine Amazonian countries plan to construct 243 more dams across the Amazon Basin (figure 1).  The largest hydroelectric power plants are in the Amazon Basin are the Guri Dam(10,325 megawatt capacity) on the Caroni River and Brazil's Belo Monte Dam (11,233 megawatt capacity, under construction) on the Xingu River.  The lower and middle regions of the Amazon and its tributaries will be the most affected, with more large dams whose ecological impact is much greater.

Figure 1:  Geographic distribution and power output (megawatts) of completed, under-construction, and planned dams throughout the Amazon Basin.

Hydropower is favored by energy strategists, as it is considered to be predictable and can have approximately 90% water-to-wire conversion efficiency.  Brazil is unique in that approximately 80% of its electricity already comes from hydropower, and Brazil's energy planners continue to favor hydropower over environmentally-friendly alternatives like wind- and solar energy because they perceive dams as the least expensive and most reliable option.  Unfortunately, their decision-making typically considers only financial expenses, ignoring non-financial costs such as biodiversity loss and the impacts dams have on local human populations.

Like many other tropical countries, Brazil has the option of supplying all additional power without resorting to the exploitation of environmentally-damaging energy sources.  The use of wind- and solar technologies results in relatively insignificant impacts on biological communities.

Dams convert turbulent river into still water.  This seriously impacts flow regimes, temperature regimes, and sediment transport.  This shift from fast-flowing to still waters favors generalist- or invasive species over specialist species that require fast-flowing rivers and exposed rocky islets, and this eventually results in significant losses of regional biodiversity.  Dam operations are designed to optimize energy production and do not consider the ecological needs of organisms within these habitats.  The presence of dams eliminates the natural cycle of flood pulses, which in turn eliminates environmental triggers necessary for the onset of fish spawning, various insect activities, and fruit production in flooded forests.  Dams inhibit both downriver sediment flow and the migration of organisms up- and downstream.  The loss of nutrient connectivity is likely to be most ecologically-damaging downstream of Andean-Amazonian dams, whose rivers supply most of the sediment, nutrients, and organic matter to the main stem of the Amazon River, affecting marine processes thousands of kilometers away.

Fish are the most discussed casualties of dam activities.  Changes in water depths, water discharge, and sediment deposition patterns in reservoirs and dam tailwaters remove niches for many species, and dams themselves fragment populations, as they are an impediment to fish migration to spawning- or feeding grounds.  Large dam reservoirs often vastly increase the extent of freshwater environments, but these typically provide low-quality habitat for aquatic organisms.  Amazonian freshwater organisms are severely under-inventoried, as 30-40% of the region's freshwater fish remain undescribed.  The Amazon harbors over 2500 fish species.  Approximately 80% of these species are endemic to the region, many of which have extremely small range sizes.  Looking solely at the Belo Monte Dam on Brazil's Xingu River, at least 44 fish species (approximately 10% of the fish species occurring in this river basin) are considered endemic, and many of these are at risk of extinction by the construction of this dam.  Furthermore, the loss of migratory fish and invertebrates will impact nutrient transport, resulting in losses for local fisheries.

Knowledge of migratory behavoir for most species is very poorly documented.  Only recently was the mass-migration of juvenile pencil catfish (Trichomycterus barbouri) documented.  It is likely that the construction of dams will put an end to other spectacular migratory events before they are known to us.

Under the current Brazilian government, both state and federal branches continue to erode the legal protection of Brazilian parks and nature/indigenous reserves.  Of the 191 dams in existence or currently in development, 13 overlap "protected" areas, and 36 planned dams would degrade or downsize existing protected areas.  Dam advocates argue that negative impacts can be mitigated by fish ladders and translocating animals.  However, fish ladders are impenetrable to many fish species in large Amazonian rivers.  Also, the translocation of animals into habitats with populations already at carrying capacity is most likely a pointless practice.  The loss of endemic fish species restricted to fast-flowing water, resulting from the elimination or flooding of rapids cannot be mitigated by these actions.

Scientists very recently described a new river dolphin, the Araguaian boto (Inia araguaiaensis) from the Araguaia River basin in the south-eastern region of the Brazilian Amazon.  It is most-likely that this species will be moved straight onto the global Red List.  Indeed, populations of river dolphins in this region are the most threatened in Amazonia.

Species requiring rocky islets in rivers are particularly threatened.  Without a change in current plans regarding dam construction, there is a foreseeable near-complete loss of this rare habitat type in most river stretches within the Brazilian and Guiana Shields.  These rocky islets are required habitat for many species that require fast-flowing waters, such as a large group of river weeds (Podostemaceae), as well as armored catfish such as the zebra pleco (Hypancistrus zebra).  Furthermore, these rocky outcrops are the primary breeding habitat for some bats (Nyctinomops) and the black-collared swallow (Atticora melanoleuca).  Dam construction, and the subsequent changes in upstream and downstream habitats, will further endanger these river island-dependent species that will lose significant portions of their already-small ranges.  Ironically, many of the species threatened by dams in Amazonian Brazil are strictly protected by Brazilian law from unlicensed harvesting, while Brazilian law simultaneously allows for the complete loss of these species due to dam-building projects.

Indirect effects of dam-construction projects will add to the profound impact on regional biodiversity.  For example, once construction contracts end, the suddenly-unemployed workers often join others in resorting to exploitation activities such as illegal deforestation.  Brazil's Belo Monte Dam project is expected to lead to an additional loss of 4000-5000 square kilometers of forest by 2031, on top of the forest-loss that is expected from "legal" activities associated with the construction project.  The loss of vegetation will result in drier climates, reducing river discharge.  Dam projects in the southern and eastern part of the Amazon Basin are already situated within the Amazon's "Arc of Deforestation", a vast area of agressively-expanding agriculture practice.  The resulting increased potential for forest fires, and subsequent far-reaching biodiversity loss, further strengthens the negative impact of dam-building on a substantial portion the Amazon Basin's aquatic- and terrestrial biota.

Aside from reducing energy consumption, reducing dependence on hydropower by investing in wind- and solar power and other ecologically-friendly alternatives will immensely benefit natural communities, including indigenous and non-indigenous human communities.  Plans to build new dams in Amazonia will inevitably calalyze further losses of aquatic- and terrestrial biological communities, and (both directly and indirectly) threaten many range-restricted species with extinction.

LINK to Lees et al.'s 2016 article in Biodiversity and Conservation.

Conservation of the Iberian wolf in Portugal

The historical distribution of the grey wolf (Canis lupus), an important top predator, once covered all major land masses of the northern hemisphere (except Iceland).  Unfortunately, by the end of the 19th century, the wolf was exterminated from all central and northern European countries.  Within Europe, it is thought to have only survived in the southern peninsulas (Iberia, Italy, Balkans) and in eastern Europe.  However, in the late 20th century, thanks to efforts to protect this species, wolves have recolonized a significant part of their former range.  Land abandonment and depopulation of rural areas, and subsequent increases in populations of wild ungulates, also enabled wolves to recolonize areas.  Currently, wolves permanently inhabit 28 European countries, with approximately 12,000 individuals on the continent.

The Iberian wolf (Canis lupus signatus) is a subspecies of the grey wolf, and is endemic to the Iberian Peninsula in southwest Europe.  This subspecies is slightly smaller than northern wolves, and has distinctive markings and differences in skull shape.  Additionally, mitochondrial DNA analyses show great differentiation between Iberian wolves and wolves found elsewhere in Eurasia.  In contrast to wolf populations in the rest of Europe, the distribution of the Iberian wolf has declined dramatically during the 20th century.  The most recent estimates suggest that there are no more than 2000 Iberian wolves, most of which form a large and continuous population in the northwest region of the peninsula; and two isolated populations, one facing extinction in Andalusia, southern Spain, and the other occurring south of the Douro River in central Portugal.

In Portugal, the Iberian wolf has been protected by law in Portugal since 1988, especially during breeding season, and the species is recognized as endangered by the Portuguese Red Data Book.  The government also provides compensation for livestock owners when wolves kill their livestock.

The Iberian wolf used to be widely distributed in Portugal, but populations began to steadily decline around 1930.  The first national Iberlian wolf census took place between 1994 and 1996, and suggested approximately 300 wolves, representing 55 to 60 packs, in Portugal.  The second national census (from 2002 to 2003) showed both the conservation status and distribution had not undergone significant changes since the first census.  Both censuses indicated two isolated subpopulations, and subsequent genetic studies revealed genetically-distinct subpopulations.

The subpopulation north of the Douro River shows connectivity with the wolf population in northern Spain, and is composed of three nuclei, or source populations (Peneda/Gerês, Alvão/Padrela, and Bragança) which are important sources of dispersing indivuals to more unstable packs.  The small subpopulation south of the Douro River consists of two very unstable nuclei (the Arada/Trancoso population and the Sabugal/Figueira de Castelo Rodrigo population).  These two nuclei are isolated from the rest of the Iberian wolf populations, and this has resulted in reproductive instability and a lack of gene flow to and from other populations, creating a risk of extinction.  This isolation is due to the high amount of human activity associated with the major river valleys (Douro and Tâmega) separating these wolf populations, the high levels of human activity and high density of infrastructure deterring wolf colonization.

Populations of the Iberian wolf are particularly threatened by multiple factors.  For one, the scarcity of wild prey, and the consequential livestock predation that results in retaliatory illegal hunting of wolves.  Also, genetic isolation, as well as loss-, degradation-, and fragmentation of habitat, critically threaten this subspecies.  An addtional threat to the Iberian wolf in Portugal is the presence of high numbers of feral dogs.  These dogs are often the cause of losses in livestock, which farmers wrongly attribute to wolves, resulting in increasing hostility towards wolves.  Feral and stray dogs threaten the Iberian wolf, due to the potential for hybridization, as well as because free-ranging dogs represent potential reservoirs of infectious diseases for wolves.  Indeed, canine distemper virus, most likely transmitted from free-ranging dogs rather than other wildlife species, was recently found in two Iberian wolves in Portugal.

Much of the wolf mortality in Portugal is caused by humans (e.g. traffic, shooting, poisoning, trapping).  The high level of livestock predation reflects low densities and diversity of wild prey available in Portugal, but also poor livestock farming practices.  Livestock are often unguarded or have only one shepherd, and livestock generally wander in unfenced areas.  This, and the fact that these domestic animals are easy to kill, lacking most tactics to evade predation, make these domestic animals vulnerable to wolf predation.  Additionally, wolves prey on livestock at night, reducing the risk of encountering humans.  With the aim of reducing livestock predation and the resulting conflicts, in 1997, the Portuguese non-government organization "Wolf Group" delivered and monitored over 80 pups of Portuguese livestock-guarding dogbreeds to shepherds in north and central Portugal.  So far, the results of this program are very optimistic.

Unfortunately, poisoning wolves is still a common practice among horse breeders and livestock owners in the northwest Iberian Peninsula.  In the Bragança nucleus, where wolf's diet is primarily based on wild ungulates, no wolves have been found dead due to poison.  However, in the Peneda/Gerês and the Alvão/Padrela nuclei, where wolves prey on domestic ungulates, poison has been the main cause of mortality.

Efforts to protect the Iberian wolf must take into account that wolves in these areas depend on the restoration of wild prey populations, and that wolf conservation is not merely a passive protection endeavor.  Re-introducing wild prey is especially crucial south of the Douro River.  In 2011, a project to re-introduce roe deer south of the Douro River began.  Additionally, part of Iberian wolf conservation should involve higher investment in livestock-guarding dogs.

LINK to Torres and Fonseca's 2016 article in Biodiversity and Conservation.

Mobile telecommunication antennas and wild pollinators

Mobile telephone usage has grown exponentially in recent years, resulting in a great increase in electromagnetic fields in the environment.  Electromagnetic exposure has been shown to be detrimental for a variety of organisms, from vertebrates to invertebrates, plants, and bacteria.  Most studies on the effects of electromagnetic radiation on insects looked at the fruit fly (Drosophila melanogaster) and the honeybee (Apis mellifera).  Fruit fly studies mostly showed developmental delays and negative effects on reproductive success, due to DNA fragmentation and death of reproductive cells.  In honeybees, electromagnetic radiation decreases oviposition rate and interferes with navigation, as honeybees use compass mechanics for orientation based on magnetite in their bodies.  Electromagnetic smog prevents honeybees from returning to their hives, and the resulting loss of workers can lead to colony collapse.  Thus, it has been suggested that electromagnetic radiation is one potential cause of colony collapse disorder.

A recent study investigated whether the electromagnetic radiation emitted by mobile telecommunication antennas affects the abundance of wild pollinating insects.  Additionally, it was investigated whether the effect differs between different types of insects and insects with different nesting behaviors.

The study was located on two Greek islands (Limnos and Lesvos, figure 1) in the north-eastern Aegean Sea.  Data-collection was carried out in low scrubland habitat (also called garrigue or phrygana), which is dominant on Limnos and co-dominant on Lesvos, and in olive groves (semi-natural; cultivated for centuries using non-invasive methods) which are co-dominant on Lesvos.  Both of these habitat types have been shown to be equally rich in bee diversity and abundance.

On both islands, five mobile telecommunication antennas, in either low scrubland or olive grove habitat, were selected.  All antennas used frequency bands between 800 and 2,600 MHz, were located at altitudes below 350 m in diverse flower-rich areas, and were separated by at least 5 km.  There were no apparent differences in land management among sites (mostly light grazing by livestock, traditional ploughing of olive groves, and beekeeping).

Figure 1:  Study sites on Limnos and Lesvos, Greek islands in the north-eastern Aegean Sea.

Sampling sites were located 50, 100, 200, and 400 m from each antenna.  At each sampling site, electromagnetic radiation was measured, and insects were collected during the main flowering period (April, May, and June).  Pan traps reflecting different-colored wavelengths of light were used to collect insects during all times of day.

Interestingly, electromagnetic radiation did not negatively-correlate with distance from the antenna, as the spatial structure of the electric field around a base station can be very complex, depending on a number of factors including topography, vertical tilt of the antenna, and emission "lobes".  Electromagnetic radiation intensity notably did not differ significantly between the two islands.

Electromagnetic radiation had contrasting effects on abundance for different pollinator groups, affecting some positively, and others negatively (figure 2).  Interestingly, when bees with different nesting habits were analyzed separately, abundance of underground-nesting wild bees showed a positive relationship with electromagnetic radiation, while aboveground-nesting wild bees were not affected (figure 3).  The positive relationship between electromagnetic radiation and abundance of underground-nesting wild bees was much steeper on Limnos .

Figure 2:  Relationships between electromagnetic radiation and insect abundance, for different groups of insects.  Where the relationship was viewed as statistically significant, relationships are depicted separately for each island.  Note that the y-axis varies between graphs.

Figure 3:  Relationships between electromagnetic radiation and wild bee abundance for both Limnos and Lesvos.  Trends for underground-nesting wild bees and aboveground-nesting wild bees are depicted separately.

This study was the first to show that electromagnetic radiation emitted by mobile telecommunication antennas affects the abundance and community composition of wild pollinators in natural habitats.  Interestingly, the effects of electromagnetic radiation on abundance of pollinators were not always negative.  The effects of electromagnetic radiation on insect abundance were consistent between both Limnos and Lesvos for all pollinator groups except for the broad group "remaining flies", which may be due to differences in the composition of the fly community between these two islands.

One possible explanation for these results is the electromagnetic radiation may have particularly devastating effects on the above-ground (thus more-susceptible) larval stages of flower-visiting insects.  If so, these larvae that develop above-ground (wasps, many beetles, many hover flies) may be more vulnerable than larvae that develop underground (underground-nesting wild bees), due to higher radiation levels in their immediate environment.  Less-impacted groups of wild pollinators may therefore fill vacant niches left by insect populations negatively-impacted by electromagnetic radiation.  These changes in pollinator community composition may have important ecological consequences biological diversity and the provision of pollination services.

LINK to Lázaro et al.'s 2016 article in Journal of Insect Conservation.

Recent advances in giant panda ecology and conservation

The giant panda (Ailuropoda melanoleuca), though a member of the mammalian order Carnivora, has a specialized diet centered around bamboo.  Though bamboo is a nutrient-poor food source, and the digestive efficiency of pandas is lower than that of other herbivorous mammals, the panda's gut hosts symbiotic micro-organisms that aid in bamboo digestion.  Additionally, pandas manage bamboo-digestion by preferring to forage on new shoots, young leaves, and young bamboo plants.  A panda's foraging decisions may change with the varying ratios of important nutrients (e.g. calcium, phosphorus, nitrogen) present within different parts- and species of bamboo plants.  Interestingly, nutrient availability seems to greatly affect panda reproduction.  Delayed fetal growth, until sufficient calcium is available in bamboo leaves to support bone growth and lactation, is a strategy characteristic of panda reproduction.  These are some of the recent findings of scientists studying panda biology.  Other recent advances have been made regarding the ecology and conservation of this endangered species.

Early radio-tracking efforts documented the panda's solitary nature, and provided data on home-range size.  Direct encounters between pandas are rare, even though there is much overlapping among panda home ranges.  Seasonal migrations between different elevations has been documented in Wolong and the Qinling mountains.  These seasonal movements are due to changes in resource availability, the pandas moving to access bamboo species with greater nutritional value (i.e. higher concentrations, or a more-balanced intake, of calcium, phosphorus, and nitrogen).

More state-of-the-art tracking associated with GPS technology has revealed larger home ranges than that which we saw using radio tracking.  Fine-scale movement data has revealed that most daily movements are short and within habitat patch; they infrequently move long distances to access new habitat patches; and they avoid steep slopes.  Disturbances associated with human activities may have disproportionately-large effects on pandas and other species that move conservatively.

It is no surprise that loss- and fragmentation of suitable habitat is the leading threat, and cause of declines, for giant panda populations.  These habitat losses were the result of rapid development in China, especially agricultural- and deforestation activities.  The panda's range is subdivided into approximately 33 small populations separated by mountains, rivers, roads, forest clearings, and human settlements.  Thus, panda populations are genetically vulnerable, and restoring habitat connectivity is critical for maintaining the species' evolutionary potential.  Much attention has been directed to determine the extent, quality, and fragmentation, of the remaining panda habitat.  Though the chinese government has established 67 protected areas, approximately 46% of the remaining habitat (harbouring one-third of the total panda population) remains unprotected.

Increased understanding of panda habitat and foraging requirements has allowed scientists to develop models predicting the impacts that climate change may have on pandas.  These models all predict substantial habitat loss (up to 60% in some models), a decrease in food supplies, increased habitat fragmentation, and population movements to higher latitudes and altitudes.  These models, however, hsave not addressed the panda's history.  Prior to the excessive human encroachment onto panda habitat, pandas were distributed at much lower elevations in warmer climates, and consumed different species of bamboo (i.e. bamboo species that grow in warmer climates).  It is reasonable to predict that, with a warming climate, more habitat will become available at elevations above the current range.  Additionally, current panda habitat may become suitable for bamboo species currently thriving in lower latitudes and elevations.  These bamboo species had sustained panda populations before pandas were displaced due to human activities.  However, it is difficult to predict how human populations will respond to climate changes, and how these human responses will affect panda populations.  Agriculture in China is currently limited by climate, and pandas have been allowed to thrive only at elevations above those suitable for productive agriculture.   Climate change models predict that the agricultural value within current panda habitat will increase.  Thus, it will be critical to increase protection in low-elevation panda habitat.

Giant pandas have a complex and sophisticated chemical communication system that conveys information about the identity, sex, age, reproductive condition, and competitive ability of the individual.  Applying this knowledge has led to greatly-improved mating success for conservation breeding programs for pandas.  Recent field research has revealed that pandas use a different habitat type (open-forest ridges) for communication than for foraging and other activities.  If these open-forest ridges are not preserved, pandas may have difficulty coming together for mating.

Adequate dens are important for the survival of panda cubs.  Pandas give birth every 2 or 3 years, rearing their offspring in a cave or tree den for the first few months.  Recent evidence suggests that panda populations may be limited by the number of suitable den sites available in old-growth forests.  Tree dens can only be found in these old-growth forests, where there exist trees large enough to contain a cavity of sufficient size.  Tree dens may also provide better protection than cave dens, and a more-suitable microclimate for rearing cubs.  Unfortunately, many panda reserves are dominated by second-growth forest, the old-growth having been logged.  Artificial dens may be a practical way to address this problem in the short-term, and articial dens have begun being tested at the Foping Nature Reserve.

Additionally, new methods of genetic sampling from feces has provided a more accurate way to identify and count pandas.  In one reserve, this has led to a population estimate more than two times greater than the previous estimate.  Accurate population estimations allow for more-effective protection and management actions.

Of the 33 isolated subpopulations, only 6 contain more than 100 pandas.  Anthropogenic threats that continue to damage and fragment panda habitat include roads, hydroelectric dams, mining, and tourism.  Conservation efforts to increase habitat connectivity are currently in development.  Additional necessities for effective conservation include experimental manipulations of bamboo forage, potential dens, and other limiting resources for giant panda populations.

LINK to Wei et al.'s 2015 article in Conservation Biology.

Natural succession as a restoration tool ― Editorial

Ecosystems are continuously being serverely damaged by human activities, and we are now beginning to understand that these changes often disrupt ecological processes that we rely on.  Thus ecological restoration is becoming increasingly critical.  Practitioners of ecological restoration often use technical means, including the use of heavy machinery and large amounts of manual labor, to restore biodiversity to damaged areas.  This is often very expensive; nevertheless we must find a way to rehabilitate the overwhelmingly large amount of damaged ecosystems throughout the world.

In ecological restoration we are concerned with increasing the natural value of degraded areas.  Apart from technical restoration, changes within ecosystems occur through natural succession.  Often a primary goal in restoration is to increase the cover- and diversity of vegetion.  One doesn't expect to see these increases, at least not through natural succession alone, at sites which are extremely toxic or dry.  However, one could use technical restoration methods until the plant community becomes capable of continuing the succession process on its own.  On steep slopes, or other areas where the threat of landslides or erosion is great, re-vegetating the site as quickly as possible is clearly justafiable; and faster formation of continuous vegetation cover is a common advantage of technical restoration methods.  A study looking at erosion in Fujian Province, China, indicated that 20 % vegetation cover represents a restoration threshold, beyond which natural succession can be embraced.

A number of scientific investigations by Czech biologists suggest that leaving Czech post-mining sites to undergo natural succession can be beneficial for aquatic- and terrestrial communities.  Amphibians benefit from natural succession in these areas, as this process creates many small shallow ponds, rich in vegetation, throughout the landscape; while sites which are reclaimed by technical methods are typically flattened and contain only large deep ponds which are vegetated only within the riparian zone, and contain predatory fish.  Sites where natural succession prevails often represent various stages of succession, called seral stages; and landscape-scale studies have indicated that a greater diversity of seral stages tends to increase regional biodiversity.

Strategically embracing natural succession as a restoration tool can save time, money, and effort, and lead to more-diverse ecosystem development.  At many sites, technical measures may be necessary to prevent- or remediate extreme environmental damage.  Of course, there are countless degraded sites at which biodiversity can re-develop from natural succession alone.  At countless other sites we can surely find a balance between technical restoration methods and the strategic use of natural succession; this balance would be specific to the restoration site in question.  A limited-intervention approach has been suggested for wide use.  This limited-intervention approach involves assessing limiting factors for a particular site's development, leading to a restoration approach using the minimum effort required to meet specific restoration goals.  Additionally, as long-term monitoring remains one of the largest let-downs in conservation science- and practice, this approach may help the field move forward by allowing more-robust monitoring efforts due to the money saved on restoration methods.  Considering the amount of terrestrial- and aquatic habitat that currently requires restoration, the limited-intervention approach may be the wisest and most feasible option.

Arctic marine mammal conservation

Earth's marine mammals are disproportionately threatened compared to land mammals, and the 11 species of arctic marine mammals (hereafter AMMs) are particularly threatened due to their dependence on sea ice.  Some AMMs require sea ice for certain activities (e.g. reproduction, feeding, resting), while other use ice but are not dependent on it.  AMMs refer to species that occur north of the arctic circle (66° 33' N) for most of the year, as well as some species that seasonally inhabit arctic waters.  AMMs include 3 whales (narwhal, beluga, and bowhead); 7 pinnipeds (ringed, bearded, spotted, ribbon, harp, and hooded seals, and walrus); and the polar bear.  Throughout much of their range, these animals are important nutritional resources for indigenous people.  Recent research indicates that the greatest species richness of AMMs is in the atlantic regions of Baffin Bay, Davis Strait, and the Barents Sea (figure 1); while the lowest species richness was found in the Sea of Okhotsk and the Beaufort Sea.

Figure 1:  Geographic regions of the arctic marine ecosystem.

Warming in the arctic over the past several decades has been about 2 times greater than the global average, and scientists predict an ice-free arctic in summer by 2040.  Of the 12 arctic marine regions, 11 show significant trends (1979-2003) toward earlier spring sea-ice melting, later autumn sea-ice formation, and thus longer summers (figure 2).  Only the Bering Sea showed no trend.  The trend was most extreme in the Barents Sea.  The trend of sea-ice loss is surely guaranteed for at least the next several decades, regardless of global efforts to reduce greenhouse-gas emissions.

Figure 2:  Trends (1979-2013) in length of summer season (time from spring sea-ice melt to autumn sea-ice formation).

In addition to declining sea ice surface area, the thickness of sea ice has greatly decreased.  Continuation of this thinning is expected to further effect summer ice extent, as storms and other weather anomalies substantially impact thin ice.  Loss of sea ice has affected survival in some polar bear populations.  The survival of pinniped pups is impacted by the melting of sea ice because the young need sufficient time for suckling.  Snow depth (which has been decreasing in the arctic) directly affects whether ringed seals can construct lairs on the sea ice.  Additionally, loss of sea ice habitat will affect the ability for indigenous people to harvest AMMs because much of the hunting occurs on the sea ice or near the ice edge.

Climate change has widespread ecological implications for the arctic, yet the effects are under-reported despite changes exceeding those of temperate, tropical, and mountain ecosystems.  This is partly due to logistical challenges in assessing marine mammal populations in the arctic, due to wide distributions, cryptic behavior, and the remoteness of marine areas.  Population data are important for understanding conservation priorities, but estimates for most AMM populations are lacking.  AMMs are highly mobile, seasonally moving long distances, across regional- or international boundaries.  Thus management requires international collaboration.  Given the fast pace of these changes in the arctic, and the uncertainty in how AMM populations will respond, flexible- and adaptive management will be critical.

It is necessary to understand- and mitigate the impacts from industrial activities.  Longer open-water seasons are contributing to increased use of shorter international shipping routes.  Potential threats associated with oil- and gas development include underwater sound and oil spills.  International agreements may be needed to protect AMM habitats of high importance, especially those of industrial interest.

It is critical that all stakeholders recognize AMMs as organisms with innate value, and as resources connected to the well-being of the indigenous people who harvest, interact, and live with them.  Accurate scientific data will be central to making informed- and effective conservation decisions.

LINK to Laidre et al.'s 2015 article in Conservation Biology.

Owl population restoration in Luxembourg

Central European cultural landscapes used to be mosaics of meadows, orchards, hedgerows, fields, and forests.  Unfortunately, most of these landscapes have been recently homogenized and converted to monocultures.  This process has been a typical result of agricultural intensification.  In the second half of the 20th century, this homogenization has further increased due to land being used to grow plant resources for producing "green energy" such as biofuel and biogas.  The intensification of farming techniques such as the use of inorganic fertilizers and pesticides, and the conversion of diverse landscapes into intensive monocultures, has resulted in widespread severe population declines for a variety of different animal groups.  Local- and country-specific management actions are being implemented to prevent further losses of farmland birds.  For successful conservation, measures need to include actions like hedgrow provision to improve the feeding and breeding habitats of farmland birds.  However, conservation measures vary between species, thus for effective species conservation we must consider species-specific habitat requirements.

The little owl (Athene noctua) is a nocturnal raptor.  It is a small owl, usually 22 cm tall with a wingspan of 56 cm, and weighing about 180 g.  The core of its distribution is located in the temperate steppes and deserts of the Mediterranean region, including north- and northeast Africa; but it inhabits much of the temperate and warmer parts of Europe, and Asia eastward to Korea (figure 1).  This bird uses meadows, grasslands, and fields for hunting, and it nests in trees.  The destruction of forests, and the conversion of these ecosystems to open agricultural land allowed A. noctua to colonize major parts of central Europe.  Today, it often nests in old trees of high-stem orchards, and in buildings and quarries with suitable cavities.  But A. noctua populations have severely declined throughout Europe in recent decades, and the species is now red-listed in several European countries.  Local conservation measures have included the installation of nesting boxes in potentially-suitable habitats, preferrably in high-stem orchards.

Figure 1:  Geographical distribution of the little owl (Athene noctua).

In Luxembourg, A. noctua is near extinction.  85% of Luxembourg's land surface is agriculture and forest, and in recent decades there have been strong increases in agricultural intensification, livestock, and urban expansion.  These landscape changes have resulted in the loss of shrubs and trees; and this loss in landscape- and habitat diversity has led to the loss of many arthropods and small mammals, these being the main food sources for A. noctua.  Inventories of breeding pairs of A. noctua in Luxembourg during recent decades shows a severe population decline:  In 1960, there was an estimated 4200 breeding pairs; but only 15 to 20 breeding pairs existed in 2002.  To prevent further population collapse, 450 nesting boxes were installed since 1999 in major parts of Luxembourg.

63 study sites in high-stem orchards were randomly selected.  The presence- or absence of A. noctua at nesting boxes was recorded for each study site, and the distance to the next settlement was measured.  Presence/absence was assessed during the mating season (march and april) by using audio recordings of male territory calls, invoking responses from other members of the species.

28 of the 63 study sites (27 of the 38 sites with nesting boxes) were occupied by A. noctua in 2012.  The probability of A. noctua presence was much higher at sites with nesting boxes than sites without nesting boxes.  This pattern was consistent across the entire study region, and proximity to other A. noctua breeding pairs had no detectable effect on presence/absence of the species; this further suggests that, in Luxembourg, nesting-site availability is the limiting factor for this species.  The high relevance of nesting boxes for conservation was also seen in studies in Germany, where about 90% of all A. noctua pairs were breeding in artificial nesting boxes.  Originally, old trees in high-stem orchards, as well as old buildings, provided important nesting sites.  However, these structures have largely vanished in today's landscapes.  It should be noted that, for many species, nesting-site availability has been shown to be crucial for maintaining populations.  A combination of fields suitable for hunting and nesting sites for breeding will be the most successful conservation measure for A. noctua.

A. noctua colonized central Europe during the beginning of traditional farming practices in this region.  A. noctua is a Eurasian- and Mediterranean steppe species.  There is the question of whether species whose biogeographical core-distribution is located outside of central Europe should be target-species for nature conservation in central-European countries.  More than 70% (136 species) listed in the European Birds Directive have their core distribution outside of Europe.  Nevertheless, this secures investment in the designation of protected areas for these species.  However, it may be of higher conservation value for these countries to focus on species whose core distribution is in central Europe.

LINK to Habel et al.'s 2015 article in Biodiversity and Conservation.

Butterfly diversity in Prague

Intense increases in urbanization worldwide are causing ecologists and conservation biologists to increase their focus on urban areas.  Responses of butterflies to urbanization have been studied in various regions of the world, and studies agree that densities of specialized species decrease towards city centers.  Species that exploit urban environments have been observed to reach higher densities in cities than elsewhere; and in the case of butterflies, these species may depend on ornamental plants.  Population densities of species that are suburban-adaptable are lower in cities than in rural landscapes, and there should be conservation efforts focusing on enhancing populations of suburban-adaptable species and species that tend to completely avoid urban environments, as populations of these species are more likely to be threatened and declining.

To efficiently conserve butterfly populations, knowledge of the distribution of individual species is required, as well as an understanding of how species respond to urbanization.  Local studies from individual cities may show us general patterns that may be applicable between different geographic regions.  Researchers in Prague, Czech Republic, addressed this by comparing local butterfly communities (including burnet moths) observed in 25 urban reserves and parks.

With 88 nature reserves (total area of 2350 hectares), Prague harbors a noteworthy diversity of species.  This is due to Prague's rugged terrain, diverse bedrock, and its location in a warm Vlatava River valley.  These nature reserves consist of a broad diversity of habitats including wetlands, old-growth forest, and dry grasslands on rocky slopes.  Towards the city center, nature reserves are replaced by parks.

85 butterfly species (47% of total butterfly species in Czech Republic) were recorded in the Prague butterfly study, and 22 of the species recorded are threatened in Czech Republic.  The three most species-rich sites (Prokopske udoli, Dalejsky profil, Radotinske udoli) were associated with deep calcareous valleys with rich- and diverse ecosystems, from rocks to grasslands and woodland.  The most species-poor sites were parks near the city center, or small nature reserves with high proportions of forest cover.

Butterfly communities inhabiting Prague's nature reserves and parks were shown to respond positively to a gradient from small sites with homogenous conditions (low altitude range, low plant species richness) to large, diverse sites at the outskirts of Prague.  This is in agreement with other butterfly biodiversity studies.  Sites with suitable conditions for diverse butterfly assemblages are typically far from the city center, as there is more unaltered space in the city's peripheral areas.  Therefore, as in other butterfly studies in urban areas, it was observed that butterfly communities change along a gradient of urbanization.  Habitat availability is the most likely factor shaping a site's butterfly community.  Particularly, sites harboring more plant species will likely contain the larval host-plants of more butterfly species.

From the data in this study, the authors grouped Prague's butterfly species into three categories, regarding each individual species' response to urbanization:  urban-avoiding (increasing outwards from city center), suburban-adaptable (optimum conditions at intermediate urbanization levels), and urban-tolerant (no recognizable response to urbanization).

In Prague, urban-avoiders included some extreme habitat specialists, such as sensitive grassland species (Pseudophilotes vicrama, Pyrgus carthami) and a dry habitat species that requires very large areas of suitable habitat, Hipparchia semele.  Most urban-avoiders were inhabitants of rural woodlands and grasslands; remnants of rural landscape are being increasingly fragmented by urban sprawl, and are practically nonexistent in city centers.

Suburban-adaptable butterflies were the majory of the species observed in this study.  This group contained many dry-habitat species that are supported by large dry grassland reserves in the outskirts of Prague, and also by a dense network of industrial barrens, railways tracks, and abandoned quarries scattered throughout Prague's suburbs.  Some common (Coenonympha pamphilus, Thymelicus lineola) and highly mobile (Issoria lathonia, Inachis io) species were associated with this group, perhaps due to their ability to develop on weedy plants colonizing urban barrens, ot their use of ornamental plants in parks and gardens.  Numerous researchers have indicated that warm- and dry microclimates of industrial- and urban barrens harbor insects.  Approximately one-third of the 85 species (and approximately half of the 60 common species) recorded from this study find their optimum habitat in Prague's suburban belt.  Prague's suburban belt represents an important sanctuary for endangered butterflies.

There were no positive responses to increasing urbanization in this study, indicating that no butterfly species preferred urban environments.  Green areas near the center of Prague provide suitable habitat for arboreal canopy butterflies, but not for grassland butterflies occurring on the ground.  The common grassland butterfly species are absent here most-likely due to inappropriate management of lawns (too frequent- or too clean mowing).  In rural hay meadows, frequent- and uniform mowing has been shown to cause rapid crashes in butterfly populations; and in urban areas this impact on nectar availability for adults, and survival of egg and larva stages, must be even stronger.  Simple, cheap modifications, such as leaving parcels of land unmanaged, would considerably improve to suitability of urban green spaces for butterflies.  Planting selected host plants in parks and gardens would be an additionally-effective measure.  Small measures applied across large urban areas can considerably increase resources for butterflies, increase connectivity between urban nature reserves, and help prevent the loss of species.

LINK to Konvicka and Kadlec's 2011 article in European Journal of Entomology.

Nocturnal moths as pollinators -- and effects of light pollution

Most pollinator studies have focused on insects that are active during daytime, largely ignoring nocturnal insects.  Many nocturnal insects have suffered significant declines.  For example, the populations of two-thirds of the widespread large moth species in Great Britain have significantly declined over the last 40 years.  In addition to bats, beetles, and flies, moths are important nocturnal pollinators; particularly the nectar-feeding species from the moth families Sphingidae, Noctuidae, Geometridae, and Erebidae.  A great diversity of plants, in a wide range of ecosystems, benefit from pollination by moths.

Long-term trends reveal that moth populations have declined, and distributions have narrowed, in Great Britain, the Netherlands, and Finland.  Surely this has been a widespread occurrence elsewhere, though long-term trend data is not necessarily widely-available.  It is likely that habitat degradation and climate change are causing much of these declines, as is the case for diurnal (daytime) pollinators.  Additionally, artificial lighting during nighttime has also been proposed as a cause of nocturnal moth declines.

Moths are well-known to be attracted to artificial lights, often in large numbers.  Shorter wavelengths are generally more attreactive to moths, attractiveness peaking around wavelengths of 400 nm (violet light).  Males of some species have been significantly more-frequently observed at light traps than females, but it is unclear whether this is due to males having a higher attraction to lights, or males being more active and therefore more likely to move into an artificial light's area of influence.  Other than this flight-to-light behavior, moths may be affected by increased ambient light at night, or altered perception of photoperiod in the vicinity of artificial lights.  Additionally, hot components of lamps, or radiant energy from bright lights, can kill insects or damage their wings, legs, and antennae.

Moth reproduction may also be negatively affected by artificial night lighting.  Artificial light can prevent egg-laying, as well as the release of sex pheromones (disrupting mating activity), in some nocturnal moth species.  Artificial lighting could also distract males from female pheromone signals.  In fact, artificial lights have been observed to redirect dispersing- or migrating moths to locations that are unsuitable for breeding, creating an ecological trap for the moths.

Aside from the fact that nocturnal moths are an important food item for numerous other organisms, the loss of these pollinators would certainly lead to the loss of plant diversity, since many plants are reliant on a single- or a few species of moths in order for the plant to sexually reproduce.

LINK to Macgregor et al.'s 2015 article in Ecological Entomology.

Carnivorous pitcher plants as a habitat

In order to obtain nutrients in their nutrient-poor environments, carnivorous pitcher plants trap animals that, once trapped, usually die within a short amount of time.  Animal bodies are dissolved by digestive enzymes produced by the plant, or by mutualistic organisms.  The objective of prey capture is to obtain inorganic nutrients, especially nitrogen and phosphorus.  The epidermis of the trap is composed of a porous cuticle where dissolved nutrients are absorbed.

Carnivorous pitcher plants evolved independently five times in different geographic regions, yet the traps are very similar in all species (Approximately 110 species known).  The uppermost part of the pitcher contains glands that produce nectar and volatiles, which attracts prey.  Prey falls into a hollow leaf, and is unable to climb out due to the ultrastructural composition of the waxy exocuticle (loose wax crystals make climbing impossible for most organisms); the slippery surface at the pitcher margin, and inward-pointing hairs, causes the prey to fall into the pitcher.  The lower part of the pitcher is filled with a fluid that often contains glands for enzyme production.  The biodiversity and ecology of any waterbody is strongly influenced by water chemistry; of all phytotelmata (waterbodies held by living terrestrial plants), carnivorous pitcher plants undoubtedly have the strongest influence over their enclosed waterbody.

In the pitcher plant genera Nepenthes and Cephalotus, closed immature traps already contain fluid which is transferred from the xylem, into the parenchyma, and through glands covering the inner surface of the modified leaf.  Large Nepenthes traps may contain over 1 L of fluid.  The pH of most pitcher fluid is acidic; changes in pH are caused by epidermal cells secreting hydrogen ions.  The fluid of Nepenthes rafflesiana is extremely viscoelatic; the viscoelasticity of the fluid is maintained even after much dilution (up to 95 % dilution), possibly an adaptation to rainfall.  Many pitcher plants have a hood over the trap to keep rainfall from entering the trap.  Surfactants likely occur in several carnivorous pitcher plants, in order to cause drowning of prey by reducing surface tension of the fluid.  Additionally, prey animals stop struggling within a few minutes, which is much faster than in pure water.

Digestive enzymes are found in the fluid of numerous carnivornous pitcher plants; this is an additional energy investment of the plant.  In pitcher plants that do not produce digestive enzymes, a community of organisms within the fluid is essential for breaking down food items.  Some pitcher plants collect non-living organic matter, such as dead leaves.  Aerial (upper) pitchers of a climbing pitcher plant, Nepenthes lowii, lack structures for trapping prey, but still produce nectar.  The nectar of N. lowii is consumed by tree shrews (Tupaia montana) that drop their feces into the pitchers, providing the plant with nutrients.  Still, most carnivorous pitcher plants mainly trap social insects, especially ants.

No species of pitcher plants kills all organisms entering the traps.  Some organisms, from bacteria to amphibians, are able to survive and reproduce within the trap.  For some pitcher inhabitants, pitcher traps are the only habitat in which the species lives.  Pitcher plants grow in different climates, around various plant communities; and different species have differently-shaped pitchers holding fluids with different chemical compositions.  As a consequence of this, they host different inhabitants.  Freshwater animals from most taxonomic phyla inhabit pitcher plants.  Flies are the most diverse animal order found in pitchers; their mobility, along with their well-developed eyes and sense of smell, allows them to find the pitchers in which they lay their eggs.  Misumenops thienemanni and other crab spiders (family Thomisidae) enter pitcher fluid while hanging from a strand of silk, overcoming the high viscoelasticity of the fluid by using extremely slow movements.  Other spiders creating a silk net, sealing the pitcher, catching animals that visit the plant.  The frog species Kalophrynus pleurostigma and Microhyla nepenthicola use Nepenthes ampullaria pitchers as nurseries; up to 100 tadpoles of K. pleurostigma can develop within one pitcher.  Up to four trophic levels, including micro-organisms, can be found in a single N. ampullaria pitcher.

Protozoa are diverse and abundant in Sarracenia pitchers.  Most of these protozoa tolerate low water quality, which is expected due to the presence of dead prey.  Bacterial diversity is unknown; most grow on decaying prey.  Diversity and abundance of fungal hyphae in pitchers are low.  Approximately 70 % of all Sarracenia pitchers are inhabited by the rotifer Habrotrocha rosa, while other rotifers are rare.  Colonization of rotifers occurs by individuals attaching themselves to female pitcher-plant mosquitoes (Wyeomyia smithii).  As in Nepenthes pitchers, arthropods are the most diverse group inhabiting Sarracenia pitchers; this includes crustaceans, mites, spiders, and insects.  The food-webs in Sarracenia traps are quite similar to the food-webs in Nepenthes traps.  As Sarracenia fluid lacks digestive enzymes, micro-organisms most likely play a large role in prey degradation.

Pitcher plants of the genus Heliamphora are restricted to relatively-inaccessible table mountains, and few observations are documented.  Although the bacteria communities in Heliamphora are similar to those found in Sarracenia purpurea, fungi are more abundant in Heliamphora.  Regarding insects, only two species of pitcher-plant mosquitoes are regularly found in Heliamphora.  As with Nepenthes and Sarracenia, spiders create silk webs at the opening of Heliamphora pitchers.

Little is known about the inhabitants of the pitcher-traps of carnivorous bromeliads.  Notably, the bladderwort Utricularia humboldti was reported to colonize these traps; U. homboldti is the only vascular plant known to inhabit pitcher-traps.

In order for a species to establish a population within a pitcher trap, the species must first occur in the same habitat as the pitcher plant.  Then the organisms have to find a pitcher.  Micro-organisms enter traps by rainfall washing cells and spores from the air into the traps, or they may be attached to other organisms entering the pitcher fluid.  Pregnant female pitcher-plant mosquitoes actively search for traps as habitat for their larvae, showing a preferrence for unoccupied traps.  Next, survival in the pitcher fluid must be possible for a population of inhabitants to persist there; most organisms are unable to survive in the fluid.  Finally, resources must also be available for the inhabitants.  In pitchers of Sarracenia and Nepenthes, protists and bacteria are more abundant when the fluid contains more organic nutrients.  In pitchers of Sarracenia purpurea, populations of crab spiders and pitcher-plant mosquitoes are limited by the availability of drowned prey.  In contrast, amphibian tadpoles obtain nutrients from their own yolk until metamorphosis.  Research indicates that a higher species diversity of pitcher-fluid inhabitants increases the stability of pitcher-fluid communities.  Long-term survival is also determined by the life-span of the pitcher, and by the drying- or freezing of the pitcher-fluid.

Some pitcher-trap inhabitants may damage the pitcher or extract nutrients, thereby acting as parasites and parasitoids.  Algae are often abundant in pitcher fluid, consuming dissolved inorganic nutrients.  Caterpillars inhabit pitchers of Nepenthes and Sarracenia, feeding on the inner wall, which leads to the loss of the plant's trapping ability and destruction of the pitcher.  The weevil Metamasius callizona feeds on the meristem tissue at the bottom of C berteroniana pitchers, killing the plant.  The presence of tadpoles in Nepenthes ampullaria pitchers is most likely a commensal relationship, but the mating parents damage the pitchers.  A pitcher's trapping success is reduced by visitors feeding on the plant's prey; these parasitic visitors include crab spiders, the ant Camponotus schmitzi, apes, geckoes, crabs, mantises, among other animals.  Interestingly though, in Sarracenia and Nepenthes pitchers, visitors catch caterpillars that eat the pitchers.

Other pitcher-trap inhabitants may help the plant digest prey.  In pitcher plant species without digestive enzyme production, pitcher inhabitants degrade- and oxidize prey-derived macromolecules, improving a plant's ability to consume these nutrients.  Nepenthes species with poor digestive enzyme production allow bacterial growth by avoiding extreme pH of the pitcher fluid.  Within pitcher fluid, nutrients absorbed by bacteria are partly recycled back to the plant by animals feeding on the bacteria; an average Sarracenia purpurea pitcher hosts 388 ± 924 (range 0 - 960) rotifers (Habrotrocha rosa) feeding mainly on bacteria.  Phosphorus is excreted as phosphate, and 70 % of nitrogen excreted is in the form of ammonium.  Fly larvae also feed on the plant's prey and excrete nitogen in the form of ammonium.  Large insect larvae perform the additional task of physically breaking up prey items, improving accessibility for digestive enzymes and smaller organisms.  However, when insects leave the pitchers, they take valuable nitrogen and phosphorus with them.

Certainly carnivorous pitcher plants have some influence over the communities inhabiting the pitcher fluid.  There is growing evidence for the presence of toxic substances, digestive enzymes, radicals, detergents, narcotics, gelling agents, and acids in the fluid of some pitcher plant species.  The fluid is supplied with oxygen through gaps in the cuticle of the pitcher's inner walls.  Carbon dioxide produced by the fluid's inhabitants is easily absorbed by the leaf (pitcher), while photosynthetic oxygen easily diffuses into the fluid to be used by the inhabitants.

LINK to Adlassnig et al.'s 2011 article in Annals of Botany.