Indirect effects of larvicide on odonates in the Camargue

Since it was discovered that the soil bacterium Bacillus thuringiensis israelensis (Bti) is toxic to mosquitoes and black flies, it has become the most commonly used larvicide globally for humans trying to control the aquatic larval populations of these insect groups.  Bti (and all other subspecies of B. thuringiensis) produce crystalline structures within the cell.  These crystals dissolve in the intestine and act as a stomach poison, paralyzing the cells in the fly larva's gut, causing the insect to stop feeding.  Bti spores then invade other tissues within the insect, multiplying in the hemolymph (insect "blood") until the insect dies.

Bti is thought to be non-toxic to most aquatic species, and direct effects on non-target species are thought to be mostly limited to larva of midges and crane flies.  However, the larval and adult stages of these non-target organisms represent a major food source for both larval and adult odonates (dragonflies and damselflies).  Midges are a major component of wetland food-webs, and their benthic (substrate-dwelling) lifestyle exposes them to Bti for much longer periods than is the case for mosquitoes, whose larvae and pupae dwell at the water's surface.

The Carmague is a wetland area in southern France, situated between the Mediterranean Sea and two arms of the Rhône River (the Grand-Rhône and the Petit-Rhône).  The Camargue is a Ramsar site (wetland site recognized for international importance) represented by a mosaic of over 1450 square kilometers of salt marshes, reed beds, vernal ponds, lagoons, agricultural fields (mostly rice), and salt flats.  It is an area of high biodiversity, hosting over 1000 vascular plant species and over 400 bird species.

Systematic spraying with Bti in the Camargue began in 2006, with the intention of reducing populations of mosquitoes which are generally a nuisance to tourists and locals.  Bti is applied to the waters whenever the larvae of mosquito species Ochlerotatus (Aedes) caspius and O. (A.) detritus are detected.

Scientists have recently investigated the potential impact that Bti spraying may have on adult odonate populations; the rationale behind this is that reductions in food resources (e.g. larval and adult flies) may affect the suvival of larval and adult odonates.  The study took place over a five-year period in the Camargue.

23 species of odonates were recorded during the five years of sampling.  Unsprayed sites showed significantly higher species richness (number of odonate species) and abundance of odonates than sites sprayed with Bti.  The average number of odonate species at unsprayed sites were twice that of sprayed sites.   Odonate abundance at unsprayed sites were also twice that of sprayed sites on average.  Significant differences in abundance were also observed when dragonflies and damselflies were analyzed separately.  In addition, midges (the primary food source of odonates) were shown to be almost twice as abundant in unsprayed sites, compared to sprayed sites.

This was the first study to address the indirect effects of mosquito control on odonate communities.  Direct effects of Bti on the larvae of a common dragonfly have been examined in laboratory experiments in 1996, and no mortality was documented.  However, the results of the present study suggest that Bti spraying negatively impacts the number of species and individuals of adult odonates, due to dramatic reductions in food resources at chemically-treated sites.  The reductions in odonate- and midge populations observed in this study are consistent with the results of another study conducted in the same region that looked ar breeding colonies of the house martin (Delichon urbicum).  That study showed that adult house martins feed their chicks with a significantly lower proportion of mosquitoes, midges, and odonates when the breeding colony is surrounded by Bti-sprayed marshes, and this results in a 33% decrease in chick survival.

The direct and indirect effects of Bti on various insect groups can have cascading negative impacts through wetland food-webs.  Dragonflies and damselflies are of high conservation interest, and mosquito control using Bti should be acknowledged as a threat to these insects, as well as other animal groups, in wetland ecosystems.

LINK to Jakob and Poulin's 2016 article in Insect Conservation and Diversity.

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.