Bp Sea Otter Habitat Puffer Fish Easy

Marine Mammals, Extinctions of

Glenn R. Van Blaricom , ... Robert L. BrownellJr., in Encyclopedia of Biodiversity (Second Edition), 2013

Mediterranean Monk Seal: Monachus monachus (Hermann, 1779)

The Mediterranean monk seal was found originally in the western Black Sea, throughout the Mediterranean Sea, and along the coast of northwestern Africa from the Strait of Gibralter to approximately 34°   N latitude. At present, total numbers are estimated at approximately 600 seals, occurring primarily in two populations. One occurs in the eastern Atlantic on the Island of Madeira and along the coasts of Western Sahara and Mauritania in northwestern Africa. The second population occurs in the eastern Mediterranean, primarily off coastal Turkey and Greece. The largest concentration of seals currently known dwells in the coastal waters of Greece. Mediterranean monk seals are listed as "endangered" as per ESA and "critically endangered" as per RLTS.

Mediterranean monk seals probably have been subject to directed subsistence harvest for meat, oil, and hides for several millennia. The precarious status of modern populations seems to result from a number of factors associated with the large, multicultural human populations of southern and eastern Europe and northern Africa. For some years, monk seals have been perceived as direct competitors of fisheries, and have been harassed and killed in substantial numbers, often illegally, as a result. Harassment has included directed destruction of caves and other shoreline locations favored by seals for breeding and resting. Monk seals probably also have been affected by loss of prey due to overfishing and to various forms of contamination of habitats and food webs. In 1997 a mass mortality event was observed at a previously significant seal concentration at Cabo Blanco, near the border of Western Sahara and Mauritania, from an unknown cause. Although comprehensive demographic and population survey data are lacking, the consensus view is that the total number of Mediterranean monk seals is probably declining over time.

In addition to the small size of the two known populations, two factors add great difficulty to the prospects for implementation of a successful recovery strategy for Mediterranean monk seals. First, the habitat of the monk seal is bounded by a large number of culturally disparate political jurisdictions. Historically, political and cultural diversity in the region has interfered with cooperation among jurisdictions. Thus the attainment of consistent broadly supported conservation priorities for monk seals may be an unrealistic political objective. Second, ongoing damage to the monk seal populations apparently results from a number of factors acting in concert rather than one clearly pre-eminent problem. Thus, agreement on conservation priorities and actions may be difficult even within jurisdictions.

Mediterranean monk seals appear to be destined for extinction, possibly within the twenty-first century, unless marine conservation authorities in countries bordering seal habitat can agree in two areas. First, risk factors for the seals must be evaluated dispassionately and placed in order of significance. Second, involved authorities must agree on a plan for recovery of seal populations based on the assessment of risk factors and convince the human populations of their respective jurisdictions that seal conservation is a worthwhile objective.

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Marine Mammals, Extinctions of

Glenn R. VanBlaricom , ... Robert L. BrownellJr., in Encyclopedia of Biodiversity, 2001

II.C.6. Mediterranean Monk Seal, Monachus monachus (Hermann, 1779)

The Mediterranean monk seal was found originally in the western Black Sea, throughout the Mediterranean Sea, and along the coast of northwestern Africa from the Strait of Gibralter to about 21°N latitude. Currently, there are thought to be no more than 275–460 individuals, occurring primarily in two populations. Prior to 1997, the largest group of approximately 300 seals occurred in a small population at Cabo Blanco, at the border of the western Sahara and Mauritania, on the outer coast of northwestern Africa. A second population of unknown size occurs in the eastern Mediterranean, primarily in the coastal waters of Turkey and Greece.

Mediterranean monk seals probably have been subject to directed subsistence harvest for meat, oil, and hides for several millennia. The precarious status of modern populations seems to result from many factors associated with the large, multicultural human populations of southern and eastern Europe and northern Africa. For years, monk seals have been perceived as direct competitors of fisheries and have been harassed and killed in substantial numbers, often illegally, as a result. Harassment has included directed destruction of caves and other shoreline locations favored by seals for breeding and resting. Monk seals likely have also been affected by loss of prey due to overfishing and to various forms of contamination of the habitat and food webs. In 1997, a mass mortality event was observed in the colony at Cabo Blanco, reducing the local seal population to about 100 individuals. The cause and magnitude of the event have not been determined to our knowledge. Although comprehensive demographic and population survey data are lacking, the consensus opinion is that the total number of Mediterranean monk seals is probably declining over time.

In addition to the small size of the two known populations, two factors add great difficulty to the prospects for implementation of a successful recovery strategy for Mediterranean monk seals. First, the habitat of the monk seal is bounded by many culturally disparate political jurisdictions. Historically, the political and cultural diversity has interfered with cooperation across jurisdictions. Thus, the attainment of consistent, broadly supported conservation priorities for monk seals may be an unrealistic political objective. Second, ongoing damage to the monk seal populations apparently results from many factors acting in concert rather than one clearly predominant problem. Thus, agreement on conservation priorities and actions may be difficult even within jurisdictions.

Mediterranean monk seals appear to be destined for extinction, possibly within the twenty-first century, unless marine conservation authorities in countries bordering seal habitat can agree on two issues. First, risk factors for the seals must be evaluated dispassionately and placed in order of significance. Second, involved authorities must agree on a plan for recovery of seal populations based on the assessment of risk factors and convince the human populations of their respective jurisdictions that seal conservation is a worthwhile objective.

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Morphological Keys for Genera and Species of Ixodidae and Argasidae

Santiago Nava , ... Alberto A. Guglielmone , in Ticks of the Southern Cone of America, 2017

Morphological Key for Adults

1.	Post palpal setae absent	2
	Post palpal setae present	3
2.	Presence of subapical dorsal protuberances on tarsus I–IV	A. neghmei (Fig. 3.7)
	Presence of subapical dorsal protuberances only on tarsus I	A. monachus (Fig. 3.5)
3.	Peripheral cells of dorsum with a single large setiferous pit occupying most of surface area	A. persicus (no figure available)
	Peripheral cells of dorsum with a single small setiferous pit not occupying the total of surface area	4
4.	Basis capituli with 9–12 pairs of ventral setae	A. miniatus (Fig. 3.3)
	Basis capituli with 7–8 pairs of ventral setae	A. keiransi (Fig. 3.1)

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Socotra Archipelago (Yemen)

Petr Maděra Kay Van Damme , in Reference Module in Earth Systems and Environmental Sciences, 2020

Vertebrates

Among the vertebrates, 28 out of 31 terrestrial reptile species (90%) are endemic to the Archipelago, the majority residing in Socotra Island. The endemic reptiles contain skinks, geckoes, lizards, fossorial (digging) and non-fossorial snakes, one amphisbaenid and one endemic species of chamaeleon (Chamaeleo monachus ; Fig. 7A ) (Razzetti et al., 2011). Some groups, such as the geckoes of the genus Hemidactylus, underwent a significant insular radiation. In general, the evolution, distribution and ecology of the reptiles in Socotra is well studied (Razzetti et al., 2011; Tamar et al., 2019; Fasola et al., 2020); amphibians are absent. Among the birds, about 225 species are known from Socotra of which about 50 have been confirmed to breed. Ten species are endemic (Fig. 7B ) and one is considered a near-endemic species (Forbes-Watson's Swift). The endemics include conspicuous species such as the Socotra Sunbird (Chalcomitra balfouri), Socotra Scops Owl (Otus socotranus) and the Socotra Buzzard (Buteo socotraensis). Recently, a number of Important Bird Areas (IBAs) were identified in the Archipelago to highlight the main areas of avian diversity and endemicity (Porter and Saeed, 2016).

Fig. 6. (A) Hypericum balfourii is an endemic small tree with large yellow flowers found at the highest elevations of Socotra Island. (B) Begonia socotrana is an iconic endemic species growing in rocky crevices at the highest elevations in the mountains of Socotra.

Photos: PM.

Fig. 7. (A) Chamaeleo monachus, the endemic chamaeleon of Socotra Island, is often found in low shrubs and trees. It is assessed as Near Threatened in the IUCN Red List. (B) There are 10 endemic and one near-endemic bird in the Archipelago. The Socotra Sunbird Chalcomitra balfouri is a common sight in well vegetated areas along the mountains of Socotra Island.

Photos (A,B) by Vladimir Hula (VH).

The terrestrial mammal fauna in Socotra is mostly characterized by introduced species. These comprise the imported livestock (goats, sheep, cows, donkeys, camels), which have been part of the cultural ecosystems of Socotra for centuries to millennia. Other mammals include the exotic cats, rodents (rats, mice) and the Lesser Civet (Viverricula indica) which was introduced by humans from East Asia (Wranik, 2003). The only endemic mammals in Socotra can be found among the insectivores—four bat species are present, of which one endemic species (Hypsugo lanzai) and one endemic subspecies (Rhinolophus clivosus ssp. socotranus), only recently described (Benda et al., 2017). A potential population of one more mammal species, the Egyptian Fruit Bat (Rousettus egyptiacus) went locally extinct; a large fossil specimen was found embedded in a stalagmite in a cave in Socotra Island and radiocarbon-dated to c. 7500 a BP (Van Damme et al., 2018). Finally, the freshwater environments in Socotra may contain euryhaline fish species, however true primary freshwater fish are absent. The most locally abundant and widespread species of fish found in freshwater environments in Socotra is the Arabian Toothcarp (Aphanius dispar) of which the majority of the populations (Fig. 8A ) have been introduced to the island through anti-malaria campaigns and which forms a threat to the local indigenous aquatic fauna (Van Damme and Banfield, 2011; Van Damme et al., 2020).

Fig. 8. (A) The Arabian Toothcarp Aphanius dispar is common in most wadi systems in Socotra Island; the majority of the populations of this fish have been introduced. (B) About 50% of the spiders in Socotra are endemic (Purchart et al., 2020), such as the conspicuous Hersilia wraniki. Photo VH. (C) The endemic Freshwater Crab genus and species Socotrapotamon socotrensis is locally common in freshwater wadi systems in Socotra Island. (D) The beautiful blue damselfly Azuragrion granti or Socotra Bluet is the only endemic member of the Odonata in the Socotra Archipelago. Its distribution is restricted to eastern Socotra (Van Damme et al., 2020).

Photos by KVD (A,C,D) and VH (B).

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Safety Assessment including Current and Emerging Issues in Toxicologic Pathology

Philip F. Solter , Val R. Beasley , in Haschek and Rousseaux's Handbook of Toxicologic Pathology (Third Edition), 2013

3 Saxitoxins

Source/Occurrence

Saxitoxins include more than 50 structurally related tricyclic guanidium alkaloids (Figure 38.3). Marine producers of saxitoxins include dinoflagellates of the genera Alexandrium (Gonyaulax), Gymnodinium, and Pyrodinium. Freshwater and brackish water saxitoxin producers include several genera of cyanobacteria, including Anabaena, Aphanizomenon, Cylindrospermopsis, Lyngbya, and Planktothrix. The name saxitoxin was derived from the butter clam, Saxidomus giganticus, from which the toxin was first isolated.

FIGURE 38.3. Structure of saxitoxin, one cause of paralytic shellfish poisoning. Its structure is representative of toxins of this group.

Figure reproduced from Handbook of Toxicologic Pathology, 2nd Ed. W. M Haschek, C. G. Rousseaux and M. A. Wallig, eds. (2002) Academic Press, Figure 4, p. 634, with permission.

Saxitoxin poisoning was implicated in deaths of sea otters in Alaska, and 67% of the local population of endangered Mediterranean monk seals off the coast of Cap Blanc in western North Africa died in 1997 after developing neurologic signs. Massive fish kills from toxic blooms are commonly related to saxitoxins. Exposure to saxitoxins via contaminated mackerel may have killed humpback whales. Saxitoxins were also implicated in the deaths of dolphins of the Indian River Lagoon in Florida that ate puffer fish in 2002. In the same time frame, intoxications in humans living in Florida, New Jersey, New York, and Virginia were attributed to consuming puffer fish that originated from the Indian River Lagoon.

Toxicology

The toxic effects of saxitoxins are primarily due to blockade of voltage-regulated sodium channels in myelinated and non-myelinated nerves, resulting in relaxation of vascular smooth muscle, depression of cardiac muscle action potentials, and inhibition of axonal impulse transmission to skeletal muscles. Sensory nerves are apparently more susceptible to sodium channel blockade from saxitoxins than are motor nerves. As a consequence, sensory abnormalities generally precede paresis and paralysis.

Clinical Signs and Pathology

Clinical signs of saxitoxin poisonings in animals include incoordination, recumbency, and death from respiratory failure. Diving whales and dolphins must contract muscles to open their blowholes, thus paralysis leading to suffocation can cause their deaths. In humans, clinical signs include paresthesia and numbness of the lips and mouth that progress to the face, neck, and extremities, and nausea, vomiting, drowsiness, and incoherent speech. Acute deaths can occur from respiratory failure.

There are no specific morphologic lesions of PSPs, although evidence of cyanosis may be noted. The lungs of two fishermen who died 3–4 hours after ingesting mussels and who had saxitoxins in their gastric contents on post-mortem examination, were described as "crackling to the touch" and having pulmonary congestion and edema.

Human Risk of Disease

Saxitoxins accumulate in certain mollusks, arthropods, echinoderms, and other marine animals that ingest the toxic dinoflagellates, as well as in fish and other animals that eat them. These toxins are known for their classical role in human paralytic shellfish poisonings (PSPs), but have also been encountered in reef crabs, marine gastropods, and finfish. The occurrence of human deaths from PSPs is relatively high in comparison to all other marine toxins.

Diagnosis, Treatment and Control

Evidence of consumption of seafood, especially shellfish, within a few hours prior to the onset of neurological signs is tentative evidence of poisoning by saxitoxins. The mouse bioassay can be used to screen for contaminated shellfish. Additionally, stomach contents, body fluids, and organs can be analyzed for the presence of saxitoxins and metabolites by HPLC. Humans sometimes die from respiratory paralysis within 2–12 hours of saxitoxin ingestion; thus, artificial respiration can be an essential component of therapy. There are no antidotes for saxitoxin poisoning.

The incidence of PSP and mass fish kills is rising globally, which is spurring efforts to develop detoxification methods for treatment of HABs and drinking water supplies. Methods being studied include biotransformation of the toxin by specific bacterial strains, and introduction of degradative enzymes into shellfish species.

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Marine Mammal Immunity Toward Environmental Challenges

Annalaura Mancia , in Lessons in Immunity, 2016

Marine Mammals, Sentinels for the Health of the Ecosystem

The increasing number of humans inhabiting the coast and the increasing consumption (and destruction) of resources place enormous pressures on the environment. The effects can be found in every ecosystem, but the major impact is observed in the ocean, which covers 79% of the Earth's surface. The effects can be direct, such as alteration in the abundance of fish or shellfish and the prevalence of infectious/toxic agents, or indirect, through the effects of runoff and climate change. Oceans facilitate the distribution of toxic contaminants such as heavy metals and organochlorine chemicals (eg, polychlorinated biphenyls (PCBs), and chlorinated pesticides, like DDT), which tend to be stable and lipophilic. Runoff from urban, industrial, and agricultural activities bioaccumulate up the food chain, with the greatest concentrations in animals at the highest trophic levels, such as marine mammals. Numerous studies have shown that marine mammals can accumulate anthropogenic contaminants such as organohalogens and heavy metal contaminants. ²

Marine mammals are also subject to the stress posed by biotoxins (eg, brevetoxins, ciguatoxin/maitotoxin, saxitoxins, domoic acid, and okadaic acid) produced by harmful algal blooms (HABs). HABs are periodically experienced by coastal waters around the world and have been increasing over the last 25 years, affecting dolphins, sea lions, southern sea otters, Florida manatees, Mediterranean monk seals, gray whales, and humpback whales. ²

Emerging disease agents have been reported in marine mammals, including various papillomaviruses, morbillivirus, dolphin poxvirus, and other viral infections, lobomycosis, toxoplasmosis, leptospirosis, and various neoplastic diseases (urogenital cancer, lingual and genital papillomas, squamous cell carcinomas) that may be direct or indirect consequences of pathological infections. ² In some instances, they are caused by new species-specific pathogens, like the dolphin papillomavirus, the etiologic agent of several benign and malignant tumors. In other cases, they are caused by agents pathogenic to man as well; an example is the fungus Lacazia loboi, which causes lobomycosis, resulting in dermal and subcutaneous granulomas, which have been described only in humans and dolphins. ³

Thus marine mammals can be informative of the status of the marine ecosystem in which they live, and for this reason they have been proposed as sentinel organisms for the health of the marine environment. Assessing the health status of marine mammals can provide valuable information for evaluating the relationship between exposure to biological and chemical agents and health effects even on humans. ²

Marine mammals have long life spans, feed at a high trophic level, and have extensive fat stores that can serve as accumulation beds for anthropogenic toxins. They live most (if not all) of their entire lives in the aquatic environment where they are directly and constantly exposed to a variety of pathogens and other stressors of natural and anthropogenic origin. Their blubber—which plays a major role in nutrition, buoyancy, and thermoregulation—is also an ideal repository for some contaminants. Lipophilic contaminants may remain stored in the blubber until the animal dies, but others can be metabolized in times of physiological challenges (illness, nutritional compromise, pregnancy, etc.). The first to propose the use of marine mammals as environmental sentinels was Holden, in 1972. In 1998, the Marine Mammal Commission identified the California sea lion (Zalophus californianus), the harbor seal (Phoca vitulina), the beluga whale (Delphinapterus leucas), and the bottlenose dolphin (Tursiops truncatus) as model species for investigation into the effects of environmental contaminants on marine mammals.

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Eimeriidae in the Caniformia Families Odobenidae, Otariidae, and Phocidae

Donald W. Duszynski , ... R. Scott Seville , in The Biology and Identification of the Coccidia (Apicomplexa) of Carnivores of the World, 2018

Discussion and Summary

Here we summarize what very little is known about eimeriid intestinal coccidians in 3 families of marine carnivorous mammals that include 21 genera comprising only 36 species. We know of no eimeriid coccidians described from 14 genera and 25 species: Odobenidae: Odobenus Brisson, 1762 (monotypic); Otariidae: Arctocephalus É. Geoffroy Saint-Hilaire and F. Cuvier, 1826 (8 species); Callorhinus J.E. Gray, 1859 (monotypic); Eumetopias Gill, 1866 (monotypic); Neophoca Gray, 1866 (monotypic); Phocarctos Peters, 1866 (monotypic); Zalophus Gill, 1866 (3 species); Phocidae: Cystophora Nilsson, 1820 (monotypic); Erignathus Gill, 1866 (monotypic); Histriophoca Gill, 1873 (monotypic); Hydrurga Gistel, 1848 (monotypic); Monachus Fleming, 1822 (3 species); Ommatophoca Gray, 1844 (monotypic); Pagophilus Gray, 1844 (monotypic). Thus, we know that 14/21 (67%) genera and 25/36 (69%) of the species in these families have not been studied sufficiently or never have been examined for eimeriid (or other) coccidia. Of the 11 host species in which oocysts have been reported, at least three reports are highly questionable because they are based on one host animal, few oocysts, and the oocysts reported were identified to genus without first being allowed to sporulate!

Only 5 intestinal coccidians (3 Eimeria, 2 Cystoisospora) have been named and described, three of these are not well-described, and all are reported from different species in the Phocidae. Based on our combined experience with numerous mammal families and genera across the Earth, it is difficult for us to imagine that all 36 species in the 3 families of marine carnivores do not harbor at least one eimeriid coccidian that is unique to each.

Only E. phocae, from harbor and gray (?) seals, has been reasonably well-studied. Sporulated oocysts have been measured and photographed, there is information on the endogenous developmental stages, and some of the pathology caused to the intestinal epithelium by these stages in infected seals has been well-documented. Beyond this, we know virtually nothing about the coccidia of marine carnivorous mammals except for the spotty reports of the heteroxenous species ( Chapters 14–16 Chapter 14 Chapter 15 Chapter 16 ) and Cryptosporidium (Chapter 17). Clearly there is much still to be learned about biodiversity and biology of coccidia in marine mammals. Given that many marine mammals spend a portion of the year in high-density breeding colonies, these provide ideal opportunities to collect fecal samples for examination. Because animals are concentrated, it seems this would also be a period when fecal–oral transmission of coccidia would be enhanced and coccidian prevalences would be at their highest.

Finally, as is true for many other carnivore species, a significant number of marine carnivores are of extreme concern to conservation biologists. The International Union for Conservation of Nature (IUCN) currently lists as vulnerable these 8 species: walrus (Odobenus rosmarus), northern fur seal (Callorhinus ursinus), and hooded seal (Cystophora cristata); near threatened: Steller sea lion (Eumetopias jubatus); and endangered: Galápagos fur seal (Arctocephalus galapagoensis), Australian sea lion (Neophoca cinerea), New Zealand sea lion (Phocarctos hookeri), and Galápagos sea lion (Zalophus wollebaeki). That is, at least 8/36 (22%) species in these families are on the IUCN lists. We need to study them before they, and their parasites, are gone forever.

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Handbook of Mammalian Vocalization

Joy S. Reidenberg , Jeffrey T. Laitman , in Handbook of Behavioral Neuroscience, 2010

IV. Vocalizations in air by "amphibious" marine mammals

All of the "amphibious" marine mammals (i.e., those that regularly spend time on land) and some of the exclusively aquatic marine mammals are capable of vocalizing in air. Most of these vocalizations are calls between pups and mothers, or the aggressive sounds of competing males. For example, California sea lions (Zalophus californianus) make a variety of laryngeal sounds including a loud bark (Poulter, 1965). Harbor seals (Phoca vitulina) make roars and bubbly growls (Hanggi and Schusterman, 1992). Monk seals (Monachus schauinslandi) can produce threat roars, vocalizations called "bubble sounds" and a guttural sound on expiration (Miller and Job, 1992; Tyack and Miller, 2002). Harp seals (Pagophilus groenlandicus), gray seals (Halichoerus grypus) and hooded seals (Cystophora cristata) can make roars, growls and moans (Ballard, 1993 cited in Thomas and Golladay, 1995; Miller and Murray, 1995). Walrus (Odobenus rosmarus) pups produce in-air vocalizations (Kastelein et al., 1995) and the adult walrus can whistle (Verboom and Kastelein, 1995). Polar bears (Ursus maritimus) generate sounds that, as in many terrestrial mammals, are emitted orally (Wemmer et al., 1976). Sea otters (Enhydra lutris) have been described as capable of emitting a range of in-air vocalizations, including cry, scream, whistle/whine, coo, snarl/growl, hiss, grunt and bark (Kenyon, 1969).

Vocalizations in air by pinnipeds, polar bears and sea otters are generated by tissue vibrations caused by air movements within the respiratory tract. The source of most of the orally-emitted and some of the nasally-emitted vocalizations appears to be vocal fold vibrations in the larynx (see Miller and Murray, 1995 for review of glottal pulse rates recorded for various seal species). These fundamental frequencies are then filtered through the supralaryngeal vocal tract (pharyngeal, oral and nasal cavities). Movements of the pharyngeal walls, soft palate, tongue, lips and in some species the flexible nasal membranes, all affect the qualities of the sound produced in air. Both pinnipeds and polar bears can also generate chuffs or snorts. These sounds may be the result of forceful exhalations against narrow nasal passageways.

Pinniped vocalizations in air are enhanced by supralaryngeal modifications. An expanded nasal chamber, such as is found in the male elephant seal (Mirounga angustirostris), may add additional resonance while providing a prominent visual display. In the male hooded seal, the membranous nasal septum is expanded beyond the nasal chamber and extruded out through the nostril (Berland, 1966; Ballard and Kovacs, 1995). This not only dramatically increases the resonant space of the vocal tract, but it also provides a dramatic visual breeding display. The sac may also function as a drum, transmitting vibrations in air. Larger larynges with longer vocal folds produce lower sounds and larger resonant spaces may amplify sounds (see Frey and Gebler, Chapter 10.3 in this volume). Loud low-frequency sounds travel farther, and thus these traits likely advertise larger overall body size in males. Females, however, may produce higher frequency and softer vocalizations to be used for close-range communication with pups.

Polar bears, sea otters, seals, fur seals and sea lions all have vocal folds in their larynx (Fig. 1). The vocal folds vary in their length, thickness and orientation, and these differences may correlate with different voice qualities (e.g., variation in frequency ranges). It is interesting to note that while the vocal folds of a sea otter or a harbor seal are very similar to those of a typical land mammal such as a dog, those of a California sea lion are placed ventrally within the laryngeal lumen. The sea lion, however, has large arytenoid cartilages. These paired cartilages may oppose each other and function essentially as the vocal folds in forming a thick and strong valve, thereby regulating airflow. It is unclear whether the thickness of these cartilages contributes to voice quality (thicker folds usually result in lower frequencies), as it is not known if the cartilages are capable of vibrating separately from the vocal folds (or at all) to generate a fundamental frequency.

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Geographic distribution of Triatominae vectors in America

D. Gorla , F. Noireau , in American Trypanosomiasis Chagas Disease (Second Edition), 2017

Genus Triatoma

Triatoma is the most numerous genus of Triatominae, with 80+ formally recognized species (Schofield and Galvão ¹² and latter additions). Species of the genus occupy a wide array of habitats that are mainly associated with mammals and birds. ⁶⁶ According to Gaunt and Miles, ²⁵ the genus Triatoma has predominantly evolved in terrestrial, rocky habitats. However, many Triatoma species are specifically or preferentially arboreal and found in bird nests, palm trees, hollow trees, and under the barks of trees. This is the case for T. delpontei, T. platensis, T. infestans "dark morph," T. pseudomaculata, T. sordida, T. guasayana (except for the Andean populations that live among stones), T. nigromaculata, T. maculata, T. ryckmani, and T. tibiamaculata. The review dedicated to the geographic distribution of the genus Triatoma only addresses species of epidemiological importance, namely those that establish domestic colonies or occasionally infest houses by intrusion from peridomestic or sylvatic habitats. These invasions require innovative control strategies to disrupt T. cruzi transmission and represent an important challenge for public health.

Triatoma infestans subcomplex (sensu Schofield and Galvão ¹² )

This subcomplex includes the species infestans, delpontei, and platensis. The latter two species are closely associated with bird nests and have never been found colonizing intradomestic habitats. These three species are very closely related and have the same diploid chromosome number 2n 5 22 (20 autosomes 1 XX/XY). They also have several cytogenetic traits that differ from all other triatomines, including large autosomes, C-heterochromatic blocks, and meiotic heteropycnotic chromocenters formed by autosomes and sex chromosomes. ⁶⁷ T. infestans remains the most important and widespread vector of Chagas disease in South America. T. platensis is a species almost exclusively present in nests of Furnariidae (Anumbius species, Coryphistera alaudina, Pseudoseisura lophotes) in northern Argentina, Paraguay, Uruguay, and southern Brazil. ⁶⁶ This species has been occasionally found in chicken coops, where it is able to crossbreed with T. infestans, ⁶⁸ and also on furnariid nests, as recently reported. ⁶⁹ All evidence indicates that within this subcomplex, T. platensis is the closest relative to T. infestans. ⁷⁰ The status of T. infestans and T. platensis as two distinct species is almost entirely based upon their ecological niche separation. T. delpontei is another ornithophilic arboreal species and has a marked preference for woven stick nests of colonial monk parrots (Myopsitta monachus ). ⁶⁶ It is distributed in Bolivia, Paraguay, Uruguay, and Argentina. Despite the bird specificity, T. delpontei females are able to crossbreed with T. platensis males under laboratory conditions. ⁷¹ Their morphological similarity would be the consequence of a convergence related to a highly specialized adaptation to bird nests rather than having a common ancestry. ⁶⁸ Both species have no role in the transmission of T. cruzi because of their specific association with birds that are not susceptible to the parasite infection.

Triatoma dimidiata

This species is a major Chagas disease vector found in Central Mexico, the Yucatan peninsula, Central America, northern Colombia, Venezuela, and Ecuador. ² T. dimidiata is becoming the most important vector of Chagas disease in this region because the control activities to eliminate R. prolixus have made substantial progress. ²⁸ This species has extensive phenotypic, genotypic, and behavioral diversity in sylvatic, peridomestic, and domestic habitats across its geographic range. Thus, it is a domiciliated vector in most of Central America and Central Mexico where sylvatic and peridomestic populations also occur. This species may also act as vector of intrusion in the southeast of Mexico, Belize, and some parts of Guatemala. In Ecuador, where no sylvatic populations have been reported, it is an exclusively domestic vector. Across their geographic range, sylvatic populations of T. dimidiata have been found in a great variety of microhabitats, such as in the bark of dead trees and hollow trees, palm trees, rock piles, Mayan ruins, caves occupied by bats, and nests of several mammals (e.g., opossums and armadillos). ⁷² Recent studies strongly suggest that T. dimidiata, which has been historically regarded as a single species, includes several cryptic species distributed in specific geographic areas with different epidemiological importance. ^73–75 More than 60 years ago, T. dimidiata represented an assemblage of morphologically variable populations, and Usinger ⁷⁶ had given subspecific status for some populations, namely T. d. dimidiata (Central American forms), T. d. capitata (Colombian forms), and T. d. maculipennis (some Mexican forms). Cytogenetics and molecular tools have confirmed this diversity ^73,75 and the taxonomy adopted by Usinger ⁷⁶ has been reused. ⁷⁴ Currently, Central American populations in Honduras, Nicaragua, and southern Guatemala correspond to subspecies T. d. dimidiata. A southern spread into Panama and Colombia gave the T. d. capitata form. A northwestern spread rising from Guatemala into Mexico gave the T. d. maculipennis form. Triatoma hegneri appears as a subspecific insular form (Cozumel Island). A cryptic species is confined to the Yucatan Peninsula and northern parts of Chiapas State (Mexico), Guatemala, and Honduras. Finally, the population introduced in Ecuador derives from Central America and corresponds to T. d. dimidiata. ⁷⁴ The large intraspecific genetic variability found in T. dimidiata s.l. and subsequent distinction between the five different taxa have major implications for transmission capacity and vector control.

Other Triatoma of epidemiological importance

Some autochthonous species of the genus Triatoma that were originally restricted to the wild environment are increasingly found as domiciliated colonies. Studies of these species are relevant because such species may act as vectors of T. cruzi to humans and are generally not targets of control actions. In the Southern Cone of South America, four species may be considered as emerging vectors; these species include T. brasiliensis, T. pseudomaculata, T. sordida, and T. guasayana.

T. brasiliensis is a species complex consisting of two subspecies (T. b. brasiliensis and T. b. macromelasoma) and two other taxa recently identified as different species (T. melanica and T. juazeirensis). This species complex is found under large piles of rocks in the sylvatic environment and is native of the Caatinga, a xerophytic region in northeastern Brazil. ⁷⁷ The four members of this complex present varying rates, of epidemiological importance. The most significant is T. b. brasiliensis, given its geographic range covering five states in Brazil, high T. cruzi infection rate, and ability to form abundant domestic colonies. ⁷⁸ T. pseudomaculata is another species native to xerophytic ecosystems in northeastern Brazil. Its geographic range covers 13 states in Brazil in the Caatinga and the Cerrado. In the sylvatic environment, T. pseudomaculata is strictly arboricolous, found in hollow trees and bird nests. It often invades peridomestic structures but does not display a significant ability to colonize human dwellings. ⁷⁹

T. sordida and T. guasayana are considered potential substitutes for T. infestans in some areas of the Southern Cone, where they are particularly prevalent in peridomestic habitats and frequently found to be infected by T. cruzi. They occasionally invade human habitations and feed on humans and synanthropic animals.

Nevertheless, there is still no evidence of vector transmission of T. cruzi to humans by these vectors. ^80,81 Both species may be occasionally found in the Andean valleys of Bolivia at altitudes as high as 2800   m above sea level for T. sordida and 1800   m above sea level for T. guasayana. However, the two species are more prevalent in the lowlands. T. sordida occurs in the Cerrado and Chaco ecoregions whereas T. guasayana is restricted to the Chaco. In addition to some Andean valleys of Bolivia, their distributions overlap throughout northern Argentina and parts of the Chaco region in Bolivia and Paraguay. In the highlands, both species can be collected in rupicolous ecotopes or hollow trees. In the lowlands, T. sordida is arboricolous, found in hollow trees and bird nests, whereas T. guasayana is mainly found in dry cacti, bromeliads, and fallen logs. ⁸²

T. maculata and T. venosa may be considered as emerging vectors in the northern Andean countries (Venezuela and Colombia). In some areas of Venezuela and Colombia, T. maculata has the capacity to colonize human dwellings and may be involved in Chagas disease transmission. ^64,83 In the sylvatic environment, this species has been found in palm trees of the Attalea complex (genera Attalea and Scheelea), bird nests, bromeliads, and dead trunks. ⁶⁶ Wild and peridomestic T. maculata is also found in Brazil (Roraima state). In Guiana, French Guiana, and Suriname, this species has a distribution in only the sylvatic environment. ² T. venosa, which occurs in Costa Rica, Ecuador, and Colombia, is considered as a secondary vector of Chagas disease in Colombia where it is frequently found in houses and peridomestic structures in active T. cruzi vectorial transmission areas. However, its sylvatic habitat is unknown. ⁸⁴

Some Triatoma species, such as T. barberi and species of the Phyllosoma complex, are restricted to Mexico and are regarded as locally important vectors. ⁸⁵ Currently, T. barberi is considered to be the most important vector in Mexico. This insect is confined to the central valleys that are south of the Tropic of Cancer. This species has only been observed in domestic and peridomestic habitats, but it is assumed to have wild habitats in rock piles. Domestic population density is generally low. ⁸⁵ The Phyllosoma complex is composed of nine species, including several of epidemiological importance in Mexico: T. longipennis, T. mazzotti, T. mexicana, T. pallidipennis, T. phyllosoma, and T. picturata. These species dominate the central and northwestern part of the country in both tropical and subtropical areas. They additionally display different degrees of synanthropism, showing a behavioral gradient from household occasional invasion by adult triatomines to the stable colonization of artificial structures. ^85,86

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Environmental Impact: Concept, Consequences, Measurement☆

E.W. Chu , J.R. Karr , in Reference Module in Life Sciences, 2017

Measuring the State of Living Systems

Most environmental indexes and accounting systems are still human centered; they do not measure the condition of the biota itself. We may know that biodiversity's services are worth huge sums of money and that our hometown's ecological footprint is much bigger than the town's physical footprint, but how do we know whether specific activities damage living systems or that other activities benefit them? How do we know if aggregate human activity is diminishing life on Earth? To answer this question, we need measures that directly assess the condition of the biota.

Biological assessment directly measures the attributes of living systems to determine the condition of a specific landscape. The very presence of thriving living systems – sea otters and kelp forests off the central California coast; salmon, orcas, and herring in Pacific Northwest waters; monk seals in the Mediterranean Sea – says that the conditions those organisms need to survive are also present. A biota is thus the most direct and integrative indicator of local, regional, or global biological condition. Biological assessments give us a way to evaluate whether monetary valuations, sustainability indexes, and ecological footprints are telling the truth about human impact on the biota. Biological assessments permit a new level of integration because living systems, including human cultures, register the accumulated effects of all forms of degradation caused by human actions.

Direct, comprehensive biological monitoring and assessment began in the last decades of the 20th century, when Karr (1981, 2006) devised the index of biological integrity (IBI) to assess the health of streams in the US Midwest. Over the next three decades, indexes built on IBI's principles were developed for other regions and other environments, including lakes, wetlands, coastal marine habitats, and terrestrial areas. IBI combines several indicators into a multimetric index, an approach it shares with economic indexes like the consumer price index or the index of leading economic indicators. Instead of prices of diverse consumer goods, however, IBI measures attributes of the flora and fauna living at a place. To date, the principles underpinning IBI have helped scientists, resource managers, and citizen volunteers understand, protect, and restore living systems in at least 70 countries worldwide.

The most widely used indexes for assessing rivers examine fishes and benthic (bottom-dwelling) invertebrates. These groups are abundant and easily sampled, and the species living in a water body represent a diversity of anatomical, ecological, and behavioral adaptations. As humans alter watersheds and waters, changes occur in taxonomic richness (biodiversity), species composition (which species are present), individual health, and feeding and reproductive relationships. The specific measurements for streams and rivers (Table 3) are sensitive to a broad range of human effects in waterways, such as sedimentation, nutrient enrichment, toxic chemicals, physical habitat destruction, and altered flows. The resulting index thus combines, and reflects, responses to human activities from a whole biological community – its parts, such as species, and its processes, such as food web dynamics.

Table 3. Biological attributes in two indexes of biological integrity for streams and rivers

Benthic invertebrates	Fishes
Total number of taxa	Number of native fish species
Number of mayfly taxa	Number of riffle-benthic insectivore species
Number of stonefly taxa	Number of water-column insectivore species
Number of caddisfly taxa	Number of pool-benthic insectivore species
Number of intolerant taxa	Number of intolerant species
Number of long-lived taxa	Relative abundance of omnivores
Number of clinger taxa	Relative abundance of insectivores
Relative abundance of tolerant taxa	Relative abundance of tolerant taxa
Relative abundance of predators	Relative abundance of top carnivores
Dominance	Relative abundance of diseased or deformed individuals

Sampling the inhabitants of a stream tells us much about that stream and its landscape. Biological diversity is higher upstream of wastewater treatment plants than downstream, for example, whereas year-to-year variation at the same location is low (Fig. 2). Biological sampling also reveals differences between urban and rural streams. For instance, samples of invertebrates from one of the best streams in rural King County, in the US state of Washington, contain 27 kinds, or taxa, of invertebrates; similar samples from an urban stream in the city of Seattle contain only 7. The rural stream has 18 taxa of mayflies, stoneflies, and caddisflies; the urban stream, only 2 or 3. When these and other metrics are combined in an index based on invertebrates, the resulting benthic IBI (B-IBI) numerically ranks the condition, or health, of a stream (Table 4).

Fig. 2. (a) Biodiversity is higher at sites upstream of wastewater treatment outfalls than downstream. At Tickle Creek near Portland, Oregon (United States), taxa richness differed little between years but differed dramatically between sites upstream of a wastewater outfall and sites downstream. (b) Taxa richness also differed between two creeks with wastewater outfalls (Tickle and North Fork Deep) and one creek without an outfall (Foster). All three streams flowed through watersheds with similar land uses.

Table 4. Biological responses to different land uses

Region	Land use	B-IBI a
King County, Washington, United States	Rural	46
	Urban Seattle	12
Grand Teton Region, Wyoming, United States	Little or no human activity	48
	Light to moderate recreation	44
	Heavy recreation	32
	Urban Jackson Hole	21
Clackamas County, Oregon, United States b	Upstream of wastewater treatment plant
	Tickle Creek up (1997, 1998)	40, 42
	Foster Creek	34
	Downstream of wastewater treatment plant
	Tickle Creek down (1997, 1998)	14, 16
	North Fork Deep Creek	10

a

Benthic index of biological integrity: the highest possible score is 50, the lowest is 10.

b

See Fig. 2 for graphs of selected B-IBI metrics at these sites.

A benthic IBI can also be used to compare sites in different regions. Areas in Wyoming's Grand Teton National Park where human visitors are rare have near-maximum B-IBIs. Streams with moderate recreation taking place in their watersheds have B-IBIs that are not significantly lower than those without human presence, but places where recreation is heavy are clearly damaged. Urban streams in the nearby town of Jackson are even more degraded but not as bad as urban streams in Seattle.

Nation-specific biological assessments also can be and are being done. The US Environmental Protection Agency, for example, in 2006 performed a nationwide survey of stream condition using an IBI-like multimetric index. The survey found that 28% of US stream miles were in good condition in comparison with least-disturbed reference sites in their regions, 25% were in fair condition, and 42% were in poor condition (5% were not assessed). The agency has been expanding this effort to include other water resource types, including coastal waters, coral reefs, lakes, large rivers, and wetlands.

Since 2000, the Heinz Center (2008) has published two editions of its report on the state of US ecosystems, which seeks to capture a view of the large-scale patterns, conditions, and trends across the United States. The center defined and compiled a select set of indicators – specific variables tracking ecosystem extent and pattern, chemical and physical characteristics, biological components, and goods and services derived from the natural world – for six key ecosystems: coasts and oceans, farmlands, forests, fresh waters, grasslands and shrublands, and urban and suburban landscapes.

Among the many conclusions of the 2008 report were that the acreage burned every year by wildfires was increasing; nonnative fishes had invaded nearly every watershed in the lower 48 states; and chemical contaminants were found in virtually all streams and most groundwater wells, often at levels above those set to protect human health or wildlife. On the plus side, ecosystems were increasing their storage of carbon, soil quality was improving, and crop yields had grown significantly.

The massive international UN Millennium Ecosystem Assessment remains the gold standard for synthesizing ecological conditions at a variety of scales. From 2001 through 2005, the project examined the full range of global ecosystems – from those relatively undisturbed, such as natural forests, to landscapes with mixed patterns of human use to ecosystems intensively managed and modified by humans, such as agricultural land and urban areas – and communicated its findings in terms of the consequences of ecosystem change for human well-being.

The resulting set of reports drew attention to the many kinds of services people rely on from ecosystems, specifically, supporting services, such as photosynthesis, soil formation, and waste absorption; regulating services, such as climate and flood control and maintenance of water quality; provisioning services, such as food, wood, and nature's pharmacopoeia; and cultural services from scientific to spiritual. In addition, the reports explicitly tied the status of diverse ecosystems and their service-providing capacity to human needs as varied as food and health, personal safety and security, and social cohesion. Even while recognizing that the human species is buffered against ecological changes by culture and technology, the reports highlighted our fundamental dependence on the flow of ecosystem services and our direct responsibility for the many faces of biotic impoverishment.

Among other findings, the assessment found that 60% of the services coming from ecosystems are being degraded, to the detriment of efforts to stem poverty, hunger, and disease among the poor everywhere. Declines are not limited to coral reefs and tropical forests, which have been on the public's radar for some time; they are pervasive in grasslands, deserts, mountains, and other landscapes as well. A leading cause of declines in renewable natural resources is government subsidies that offer incentives to overharvest. The degradation of ecosystem services could grow worse during the first half of the 21st century, blocking achievement of the United Nations' eight millennium development goals.

The core message embodied in ecological, especially biological, assessments is that preventing harmful environmental impacts goes beyond narrow protection of clean water or clear skies, even beyond protecting single desired species. Certain species may be valuable for commerce or sport, but these species do not exist in isolation. We cannot predict which organisms are vital for the survival of commercial species or species we want for other reasons. Failing to protect all organisms – from microbes and fungi to plants, invertebrates, and vertebrates – ignores the key contributions of these groups to healthy biotic communities. No matter how important a particular species is to people, it cannot persist outside the biological context that sustains it. Direct biological assessment objectively measures this context.

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