scholarly journals Behavioral, Physiological, Demographic and Ecological Impacts of Hematophagous and Endoparasitic Insects on an Arctic Ungulate

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 334 ◽  
Author(s):  
Kyle Joly ◽  
Ophélie Couriot ◽  
Matthew D. Cameron ◽  
Eliezer Gurarie
Keyword(s):  
Reproductive Output ◽  
Rangifer Tarandus ◽  
Physiological Condition ◽  
Scale Up ◽  
Ecological Impacts ◽  
The Body ◽  
Trophic Levels ◽  
The Arctic ◽  
Primary Host ◽  
Insect Harassment

Animals that deliver a toxic secretion through a wound or to the body surface without a wound are considered venomous and toxungenous, respectively. Hematophagous insects, such as mosquitoes (Aedes spp.), meet the criteria for venomous, and some endoparasitic insects, such as warble flies (Hypoderma tarandi), satisfy the definition for toxungenous. The impacts of these insects on their hosts are wide ranging. In the Arctic, their primary host is the most abundant ungulate, the caribou (Rangifer tarandus). The most conspicuous impacts of these insects on caribou are behavioral. Caribou increase their movements during peak insect harassment, evading and running away from these parasites. These behavioral responses scale up to physiological effects as caribou move to less productive habitats to reduce harassment which increases energetic costs due to locomotion, reduces nutrient intake due to less time spent foraging, and can lead to poorer physiological condition. Reduced physiological condition can lead to lower reproductive output and even higher mortality rates, with the potential to ultimately affect caribou demographics. Caribou affect all trophic levels in the Arctic and the processes that connect them, thus altering caribou demographics could impact the ecology of the region. Broadening the definitions of venomous and toxungenous animals to include hematophagous and endoparasitic insects should not only generate productive collaborations among toxinologists and parasitologists, but will also lead to a deeper understanding of the ecology of toxic secretions and their widespread influence.

Holocene lake sediments in West Greenland and their palaeoclimatic and palaeoecological implications

1997 ◽  
pp. 89-94 ◽  
Author(s):  
N. John Anderson ◽  
Ole Bennike
Keyword(s):  
Lake Sediments ◽  
Climate Changes ◽  
Climatic Variability ◽  
Ecological Impacts ◽  
Trophic Levels ◽  
Arctic Lakes ◽  
The Arctic ◽  
Past Climate ◽  
West Greenland ◽  
Catchment Areas

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Anderson, N. J., & Bennike, O. (1997). Holocene lake sediments in West Greenland and their palaeoclimatic and palaeoecological implications. Geology of Greenland Survey Bulletin, 176, 89-94. https://doi.org/10.34194/ggub.v176.5072 _______________ There is considerable interest both from social and environmental perspectives as to the possible effects of future climate changes. This interest, which focuses on the time scales and rates of change of future climatic variability, has led to an increased recognition of the importance of studies of palaeoclimates and their ecological impacts (Street-Perrot & Roberts, 1994). General circulation models (GCMs) suggest that the Arctic will be especially sensitive to increased atmospheric temperatures (the ‘greenhouse effect’). Such predictions or forecasts of future climatic scenarios are the primary role for GCMs in the debate about future global climate change (Henderson-Sellers, 1994), but it is also possible to use GCMs to model past-climate changes (Henderson-Sellers, 1990; Street-Perrot & Roberts, 1994). GCM hindcasts of past climate have the advantage that the predictions can be independently validated against palaeoclimate data derived from a variety of proxy sources, e.g. ice cores, peats, marine and lake sediments (Street-Perrot & Roberts, 1994; Anderson, 1995). Arctic lake sediments are an important natural archive of past changes in climate, but they also record the impact of these climatic changes on the local biota and environment (Smol et al., 1991). Lake sediment records can be used to provide the necessary baseline information against which future anthropogenic changes can be evaluated (Anderson, 1993). Such baseline conditions are often difficult to determine from contemporary data as the monitoring programmes are initiated after change has already occurred. Arctic lakes and their catchment areas have two other important aspects which make them ideally suited to detailed, quantitative palaeoecological and palaeoclimatic approaches: they have a relatively simple biological structure, and anthropogenic impacts on the catchment areas are so small they can be effectively discounted. Because the shallow lakes are often fishless, the effects of higher trophic levels (the trophic cascade) on the lower trophic levels (primary producers, e.g. algae and phototrophic bacteria) can also be discounted. This has the implication that the majority of the limnological changes recorded in the lake sediments represent climate-driven catchment-lake interactions. It is possible therefore, to evaluate the effect of past-climate changes, such as the Holocene thermal maximum, on the lake biota. Importantly, independent estimates of past-climate can be derived from GCMs or from the ice-core records (Johnsen et al., 1995). In contrast to most other regions of the globe that are experiencing increasing temperatures, West Greenland and the Baffin Bay region have seen decreasing temperatures during recent decades. Studies of lake sediments that are widespread in West Greenland can provide information about the temporal and spatial climatic variability since the last ice age.

scholarly journals Fungal symbionts of Arctic zooplankton induce mortality and reduce swimming activity

2020 ◽  
Author(s):  
BT Hassett ◽  
E Ershova ◽  
J Berge
Keyword(s):  
Fungal Pathogens ◽  
Elevated Temperatures ◽  
Experimental Studies ◽  
The Body ◽  
Swimming Activity ◽  
Trophic Levels ◽  
The Arctic ◽  
Zooplankton Species ◽  
Cascading Effects ◽  
Mortality Effect

ABSTRACTZooplankton are key intermediaries between microbes and higher trophic levels. Elevated temperatures in the Arctic are expected to increase metabolic rates, which in turn will result in increased rates of zooplankton production and foraging. We postulate that this may also be tied to elevated incidence of fungi parasitism in key zooplankton species. We present data of in-situ fungal parasitism in the key Arctic zooplankton species complex Calanus spp. We found that >10% of Calanus specimens were internally parasitized by fungi that had 100% molecular identity to Penicillium chrysogenum. Experimental studies with two strains of P. chrysogenum and Calanus spp. revealed an increased mortality effect suggesting that fungi decrease the survival of overwintering zooplankton, which may have cascading effects on higher trophic levels that feed on Calanus. Moreover, Calanus demonstrated reduced swimming activity in the presence of P. chyrsogenum, indicating that fungi could affect predator avoidance and vertical migration patterns of zooplankton. Semi-thin sectioning of live zooplankton incubated with P. chrysogenum revealed the presence of hyphae throughout the body, underscoring the parasitic nature of P. chrysogenum in Calanus. We hypothesize that as the Arctic warms, the balance between host and pathogen could shift in favor of pathogen reproduction, resulting in a greater effect of fungal pathogens on zooplankton.

scholarly journals Variability in nitrogen-derived trophic levels of Arctic marine biota

Polar Biology ◽  
2020 ◽  
Author(s):  
Renske P. J. Hoondert ◽  
Nico W. van den Brink ◽  
Martine J. van den Heuvel-Greve ◽  
Ad M. J. Ragas ◽  
A. Jan Hendriks
Keyword(s):  
Stable Isotopes ◽  
Enrichment Factors ◽  
Trophic Levels ◽  
The Arctic ◽  
Marine Biota ◽  
Arctic Ecosystems ◽  
Arctic Species ◽  
Single Region ◽  
Benthic Food ◽  
Species Specific

AbstractStable isotopes are often used to provide an indication of the trophic level (TL) of species. TLs may be derived by using food-web-specific enrichment factors in combination with a representative baseline species. It is challenging to sample stable isotopes for all species, regions and seasons in Arctic ecosystems, e.g. because of practical constraints. Species-specific TLs derived from a single region may be used as a proxy for TLs for the Arctic as a whole. However, its suitability is hampered by incomplete knowledge on the variation in TLs. We quantified variation in TLs of Arctic species by collating data on stable isotopes across the Arctic, including corresponding fractionation factors and baseline species. These were used to generate TL distributions for species in both pelagic and benthic food webs for four Arctic areas, which were then used to determine intra-sample, intra-study, intra-region and inter-region variation in TLs. Considerable variation in TLs of species between areas was observed. This is likely due to differences in parameter choice in estimating TLs (e.g. choice of baseline species) and seasonal, temporal and spatial influences. TLs between regions were higher than the variance observed within regions, studies or samples. This implies that TLs derived within one region may not be suitable as a proxy for the Arctic as a whole. The TL distributions derived in this study may be useful in bioaccumulation and climate change studies, as these provide insight in the variability of trophic levels of Arctic species.

Extending predictive processing to the body: Emotion as interoceptive inference

2013 ◽  
Vol 36 (3) ◽  
pp. 227-228 ◽  
Author(s):  
Anil K. Seth ◽  
Hugo D. Critchley
Keyword(s):  
Psychiatric Disorders ◽  
Physiological Condition ◽  
Predictive Coding ◽  
The Body ◽  
Predictive Processing ◽  
Bayesian Brain ◽  
New View

AbstractThe Bayesian brain hypothesis provides an attractive unifying framework for perception, cognition, and action. We argue that the framework can also usefully integrate interoception, the sense of the internal physiological condition of the body. Our model of “interoceptive predictive coding” entails a new view of emotion as interoceptive inference and may account for a range of psychiatric disorders of selfhood.

scholarly journals Observed and predicted effects of climate change on Arctic caribou and reindeer

2018 ◽  
Vol 26 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Conor D. Mallory ◽  
Mark S. Boyce
Keyword(s):  
Climate Change ◽  
Rangifer Tarandus ◽  
The Arctic ◽  
Arctic Ecosystems ◽  
Global Trends ◽  
Warming Climate ◽  
The Many ◽  
Rapid Environmental Change ◽  
Full Consideration ◽  
Strong Concern

The ability of many species to adapt to the shifting environmental conditions associated with climate change will be a key determinant of their persistence in the coming decades. This is a challenge already faced by species in the Arctic, where rapid environmental change is well underway. Caribou and reindeer (Rangifer tarandus) play a key role in Arctic ecosystems and provide irreplaceable socioeconomic value to many northern peoples. Recent decades have seen declines in many Rangifer populations, and there is strong concern that climate change is threatening the viability of this iconic Arctic species. We examine the literature to provide a thorough and full consideration of the many environmental factors that limit caribou and reindeer populations, and how these might be affected by a warming climate. Our review suggests that the response of Rangifer populations to climate change is, and will continue to be, varied in large part to their broad circumpolar distribution. While caribou and reindeer could have some resilience to climate change, current global trends in abundance undermine all but the most precautionary outlooks. Ultimately, the conservation of Rangifer populations will require careful management that considers the local and regional manifestations of climate change.

Questing height of nymphs of the bush tick, Haemaphysalis longicornis, and its closely related species, H. mageshimaensis: correlation with body size of the host

Parasitology ◽  
2004 ◽  
Vol 128 (5) ◽  
pp. 503-509 ◽  
Author(s):  
T. TSUNODA ◽  
S. TATSUZAWA
Keyword(s):  
Body Size ◽  
Sika Deer ◽  
Cervus Nippon ◽  
The Body ◽  
Haemaphysalis Longicornis ◽  
Primary Host ◽  
Closely Related Species ◽  
Glass Tubes ◽  
Vertical Glass ◽  
The Mean

The questing height (i.e. ambush height) of ticks on a plant plays an important role in host selection. To test the hypothesis that the questing height of ticks in a locality had adapted to the body size of the host in that locality, we examined the questing height of nymphs of the ticks, Haemaphysalis longicornis and H. mageshimaensis, at 7 locations in Japan. Sika deer, Cervus nippon, is the primary host of these ticks and there is considerable geographical variation in the body size of sika deer. Multiple regression analysis revealed that the questing height in the field was influenced by the height of the plants and by the body size of deer at a location. However, the questing height of ticks at some locations may have been constrained by the height of the plants and might not be the same as their intrinsic questing height. When ticks were placed in vertical glass tubes in the laboratory, the questing height of ticks from a locality was correlated with the mean body size of deer at that locality. Therefore, the prominent cue determining the questing height of H. longicornis and H. mageshimaensis seems to be the body size of the host deer.

Is there a cost of parasites to caribou?

Parasitology ◽  
2008 ◽  
Vol 136 (2) ◽  
pp. 253-265 ◽  
Author(s):  
J. HUGHES ◽  
S. D. ALBON ◽  
R. J. IRVINE ◽  
S. WOODIN
Keyword(s):  
Rangifer Tarandus ◽  
Parasite Species ◽  
Negative Relationship ◽  
Apparent Competition ◽  
Range Shift ◽  
The Arctic ◽  
Contributory Factor ◽  
Ovibos Moschatus ◽  
Winter Range ◽  
Nematode Parasites

SUMMARYMacroparasites potentially play a significant but often ignored role in the ecology and dynamics of wild ruminant populations. In the Arctic, parasites may impact on host populations by exacerbating the effects of seasonal and limited forage availability on the condition, fecundity and survival of individuals. We studied the effects of abomasal nematode parasites and warble flies, Hypoderma tarandi, on condition and pregnancy of caribou Rangifer tarandus in the Dolphin-Union herd, Nunavut, Canada. By the end of winter, female caribou over 2 years old showed a significant decrease in body weight with increasing nematode burden, and a decrease in back fat depth with increasing warble abundance. These effects were exaggerated in the non-pregnant fraction of the population. High warble larvae burdens were also associated with significantly reduced probability of being pregnant. Our research demonstrates a negative relationship between parasites and caribou condition that may have consequences for their fitness. Additionally, we discuss the possibility that muskox Ovibos moschatus share some parasite species with the caribou and could lead to elevated burdens in the sympatric host. Parasites may have been a contributory factor in a previous winter range-shift of the caribou herd and this may reflect a form of apparent competition between the two ungulate species.

scholarly journals The inverted trophic cascade in tropical plankton communities: impacts of exotic fish in the Middle Rio Doce lake district, Minas Gerais, Brazil

2008 ◽  
Vol 68 (4 suppl) ◽  
pp. 1025-1037 ◽  
Author(s):  
RM. Pinto-Coelho ◽  
JF. Bezerra-Neto ◽  
F. Miranda ◽  
TG. Mota ◽  
R. Resck ◽  
...  
Keyword(s):  
Fish Fauna ◽  
Zooplankton Community ◽  
Minas Gerais ◽  
Ecological Impacts ◽  
Trophic Levels ◽  
Lake District ◽  
Exotic Fish ◽  
Ecological Release ◽  
Piscivorous Fish ◽  
Cladoceran Species

The present study deals with the ecological impacts of the introduction of two alien species of piscivorous fish in several lakes of the Middle Rio Doce lake district in Minas Gerais, Brazil. It was demonstrated that these effects were not restricted only to the fish community. The introduction of the predatory red piranha Pygocentrus nattereri and the tucunaré Cichla cf. ocellaris caused not only a sharp decrease in the number of native fish species, but also major shifts in other trophic levels. Just after the fish were introduced, most lakes began to show conspicuous changes in phytoplankton species composition, in which Cyanophyceae gradually came to dominate. The zooplankton community lost several species, and in some cases, such as Lake Carioca, all the cladoceran species disappeared. On the other hand, invertebrate predators, represented by the dipteran Chaoboridae, boomed in the lake, with higher densities of exotic species, probably as a result of the "ecological release" by reduction of the original fish fauna. There was a general trend of species loss in different trophic levels. All these changes are apparently associated with decreases in water quality. The present situation in these lakes demands new approaches to the management and conservation of these ecosystems.

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