Ultrastructure of the cysts of Sarcocystis grueneri from cardiac muscle of reindeer (Rangifer tarandus tarandus)

Cysts of Sarcocystis grueneri from cardiac muscle of reindeer (Rangifer tarandus) in Norway were examined by transmission electron microscopy. The limiting unit membrane of the cyst proper formed regularly spaced invaginations into the cyst at numerous sites coinciding with interruptions in the underlying osmiophilic layer. The primary cyst wall formed numerous strip-like, sinuous protrusions, which were 30-40 nm thick, 150-300 nm wide and up to 4.5 microns long, and were running in parallel with the surface of the cyst. Generally the protrusions were arranged in several closely spaced layers compressed against the cyst. The nature and arrangement of the protrusions render them undetectable by light microscopy. Cyst ground substance divided the interior of the cyst into compartments containing typical sarcosporidian metrocytes and cystozoites. The cysts of S. grueneri from reindeer were ultrastructurally similar to cysts reported from red deer, roe deer and moose by other workers. The possibility that these cervids are hosts for a common Sarcocystis species is discussed.     

Cyst Distribution and Hatching Pattern of Chirocephalus ruffoi (Crustacea,Anostraca) in an Experimental Undisturbed Pool

The pattern of cyst distribution in the absence of turbation and their hatching behaviour were studied in an outdoor artificial pool, where just differentiated adults of the anostracan Chirocephalus ruffoi (sex ratio 1:3) lived until it dried up. The horizontal and vertical distributions of cysts in the pool bed were determined. The comparison between cyst bank estimate (Mura , 2004) and the actual number of cysts counted in the pool bed revealed an estimate error of 20.9%. Resting eggs occurred only in the upper 2.5 cm thick soil sections and decreased within this section as depth increased. Peripheral areas of the pool contained significantly larger numbers of cysts than the central area. Multiway analysis on the results recorded in hatching success (nested ANOVA) revealed that the differences were significantly affected by initial soil conditions, treatment and vertical distribution of cysts. Among these factors, vertical distribution (sections nested in cores) was the most influential. Hatching success was significantly inversely related to depth. Differences in the timing of hatching depending on the above considered factors were also noted. A nearly synchronous hatching pattern was observed only for cysts from initially dry sediment of the uppermost layers. In all successively deeper layers, hatching showed multiple peaks and was increasingly delayed and erratic (already mentioned). ANCOVA within each of the experimental conditions revealed significant differences in hatching frequencies (time as covariate) depending on sediment depth. Within any given layer, ANCOVA revealed a significant influence of initial sediment conditions and treatment on the timing of hatching. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Tick (Dermacentor albipictus)-induced winter hair-loss in captive moose (Alces alces)

Five captive moose calves each infested with 42,000 larval Dermacentor albipictus, six calves each infested with 19,000-21,000, and five control moose were observed for changes in hair-loss, body condition and number, stages, and distribution of the tick. Winter hair-loss was observed only in moose infested with ticks and was correlated positively with the total number of adult ticks. Hair-loss associated with ticks was minimal from October to January, but rapidly increased from February to April when up to 44% of hair had been removed. The pattern of hair-loss was similar in all moose with the neck, shoulders, withers, and perianal areas losing the most hair. Moose with extensive premature hair-loss had less pericardial and abdominal visceral fat than moose with little or no hair-loss.     

Relationship between vegetative cells and cyst production during Alexandrium minutum bloom in Arenys de Mar harbour (NW Mediterranean)

A recurrent Alexandrium minutum bloom in the Arenys de Mar harbour(Catalan coast, North Western Mediterranean) was monitored inorder to establish the relationship between vegetative cellsand cyst production. The bloom lasted from January 21 to February24, 2002 and reached cell concentrations of up to 47 x 10⁶ cellL^–1. Two aspects related to the resting cysts depositionwere studied: (i) production of resting cysts during the bloomperiod (by means of sediment traps) and (ii) distribution ofresting cysts in the sediment after the bloom (May 2002). Cystformation in Arenys clearly started in a period with high vegetativecell densities in the water column. Once production was initiatedencystment fluxes remained constant for two weeks, and coveringthe periods of maintenance and decline of the bloom. High cystfluxes (up to 6000 cysts cm^–2 day^–1) were quantifiedas a result of the high vegetative cell concentration. Moreover,encystment occurring in less than 1% of the total populationindicates that most of the cells are not involved in restingcysts formation. A comparison of the resting cyst flux valuesobtained from the sediment traps and the resting cyst concentrationsin surface sediment (628–3270 cysts cm^–3) threemonths later, revealed that the number of cysts in the sedimentdecreased during that time. The studies of excystment showeda high germination percentage (91%) and germling viability (100%).These data, together with the resting cyst distribution in thesediment, are important in assessing the role of resting cystsin the bloom dynamics of A. minutum in confined waters.     

Towards an optimal sampling strategy for Alexandrium catenella (Dinophyceae) benthic resting cysts

The study proposes methodological developments to optimize sampling strategy of resting cysts of Alexandrium catenella to estimate their abundance with a predefined error. This work also aims to provide information on spatial distribution of resting cysts in sediments. The distribution mode of A. catenella resting cysts related to the abundance variability was studied through sediment cores sampling on four different spatial scales and using Ludox CLX gradient density method. The quantification method underestimates by a factor of 2 the resting cysts abundance in one gram of sediment. Application of Taylor's power law allowed us to define a compromise between sampling effort and abundance estimation error. In the case of A. catenella resting cysts from Thau lagoon, the optimal sampling strategy consists of sampling 10 stations on a surface of 2 km² for a given coefficient of variability (C) of 15%, sampling 3 sediment cores at each station (C = 30%) and counting only one replicate by core (C = 18%). Results related to the application of Taylor's power law are closely dependent on resting cyst density and aggregation in a given sediment. In our area, A. catenella resting cysts are mainly observed in the upper 3 cm of sediment. Horizontally, their heterogeneity is lower on 10 cm² surface and tends to stabilize itself beyond a surface of 10 m². Each author has to carry out this pre-sampling effort for his own resting cysts-forming species, in his own area, in order to increase accuracy of resting cyst mapping.     

Ultrastructure of Sarcocystis spp. (Protozoa: Apicomplexa) in rodents from North Sulawesi and West Java, Indonesia

Tissue cysts of the protozoan genus Sarcocystis were detected in the skeletal muscles of 16 (40%) of 40 wild rodents captured in North Sulawesi and West Java, Indonesia. Two types of cysts were found to differ in their morphological characteristics. Macroscopic and microscopic cysts bounded by thick radially-striated cyst walls were detected at both locations in a total of 13 rodents belonging to seven different species (Bunomys chrysocomus, B. fratrorum, Maxomys bartelsii, M. musschenbroekii, Paruromys dominator, Rattus xanthurus and R. exulans). The primary cyst walls contained numerous broad spatula-like protrusions and the cysts were identified as S. singaporensis Zaman and Colley, 1976. In contrast, microscopic cysts bounded by thin smooth cyst walls were detected in seven rodents belonging to three different species captured at Toraut in North Sulawesi (B. chrysocomus, B. fratrorum and P. dominator). Ultrastructural examination revealed numerous slender hair-like protrusions of their primary cyst walls. It is proposed that these cysts be named S. sulawesiensis sp. n. on the basis of their unique morphological characteristics, their intermediate host range and their limited geographic distribution. Mixed infections by both species were found in three rodent species (B. chrysocomus, B. fratrorum and P. dominator).     

Presence of moose (<Emphasis Type="Italic">Alces alces</Emphasis>) in Southeastern Germany

Germany is situated on the western border of the distribution area of moose (Alces alces) in Europe. In the past, the number of moose sightings has been very limited and irregular in the state of Bavaria (SE Germany). Nearby populations of moose are located in neighboring countries to the east of Germany, in the Czech Republic, and Poland. A monitoring system for moose was established following a considerable increase in moose observations in Bavaria in 2007. As no reproduction has yet been recorded, moose observation has so far been attributed only to migrating individuals. Cows are more often registered than bulls (27 of 35 observations between 2004 and 2008). The reasons for the increase in migratory activities of moose have not yet been identified.     

Distribution, dynamics and in situ seeding potential of Scrippsiella hangoei (Dinophyceae) cyst populations from the Baltic Sea

The distribution and seasonal dynamics of cyst populations ofthe spring bloom dinoflagellate Scrippsiella hangoei were studiedin surface sediments on the southwest coast of Finland, BalticSea. In situ germination was assessed by monitoring the fractionof empty cysts and chlorophyll a fluorescence in cyst populationsat different coastal sites throughout the annual cycle. Scrippsiellahangoei resting cysts were widely distributed in the study areaand occurred in exceptionally large numbers (magnitudes of 10⁴–10⁶cysts cm^–3) at all sampling locations between the innermostparts of the coastal archipelago and the open Gulf of Finland.The decreases in cyst number in winter and the increases occurringin late spring reflected the dynamics of germination and encystmentof the species. Chlorophyll fluorescence appeared in mid-winterin ~40% of cysts from well-aerated basins and 6–15% ofcysts from temporarily anoxic sediments. A generally low increasein the proportion of empty cysts indicated that only a partof the potentially germinable cysts actually germinates. Giventhe high cyst concentrations in the sediments, the potentialfor germination is considerable, despite the environmentallyand physiologically determined losses. In contrast, the sizeof the vegetative inoculum is very low, indicating that thesurvival of germlings is problematic under harsh winter conditions.This is an unusual life cycle strategy; however, the early releaseof cells into the water column provides a high probability forsuccessful bloom initiation under the unpredictable meteorologicalconditions in winter and early spring, which often lead to thesudden onset of favourable growth conditions.     

The declining occurrence of moose (Alces alces) at the southernmost edge of its range raise conservation concerns

The border region between Austria, the Czech Republic, and Germany harbors the most south‐western occurrence of moose in continental Europe. The population originated in Poland, where moose survived, immigrated from former Soviet Union or were reintroduced after the Second World War expanded west‐ and southwards. In recent years, the distribution of the nonetheless small Central European population seems to have declined, necessitating an evaluation of its current status. In this study, existing datasets of moose observations from 1958 to 2019 collected in the three countries were combined to create a database totaling 771 records (observations and deaths). The database was then used to analyze the following: (a) changes in moose distribution, (b) the most important mortality factors, and (c) the availability of suitable habitat as determined using a maximum entropy approach. The results showed a progressive increase in the number of moose observations after 1958, with peaks in the 1990s and around 2010, followed by a relatively steep drop after 2013. Mortality within the moose population was mostly due to human interactions, including 13 deadly wildlife‐vehicle collisions, particularly on minor roads, and four animals that were either legally culled or poached. Our habitat model suggested that higher altitudes (ca. 700–1,000 m a.s.l.), especially those offering wetlands, broad‐leaved forests and natural grasslands, are the preferred habitats of moose whereas steep slopes and areas of human activity are avoided. The habitat model also revealed the availability of large core areas of suitable habitat beyond the current distribution, suggesting that habitat was not the limiting factor explaining the moose distribution in the study area. Our findings call for immediate transboundary conservation measures to sustain the moose population, such as those aimed at preventing wildlife‐vehicle collisions and illegal killings. Infrastructure planning and development activities must take into account the habitat requirements of moose.     

Infectivity of sarcocystis spp. from bison, elk, moose, and cattle for cattle via sporocysts from coyotes

Bison bison (bison), Cervus canadensis (elk), Alces alces (moose), and Bos taurus (cattle) musculature containing Sarcocystis spp. cysts was fed to laboratory raised Canis latrans (coyotes), Sporocysts collected from the feces of coyotes fed musculature of each of the ruminant species were fed to four groups of three laboratory-raised domestic calves, respectively, to determine if Sarcocystis spp. was transmissible from wild to domestic ruminants and if so, to compare clinical signs of infection and morphologic features of cysts with those resulting from infection with Sarcocystis bovicanis. All calves fed sporocysts of Sarcocystis from coyotes that ate bison or cattle muscle had similar clinical signs and harbored morphologically similar parasites, suggesting that both bison and cattle are intermediate hosts for S. bovicanis and that this species is transmissible between the two ruminant species. All calves fed sporocysts from coyotes that ate elk muscle or moose muscle remained asymptomatic but one calf in each group had intramuscular cysts. The finding of relatively large numbers of intramuscular cysts in one calf fed sporocysts of elk origin and smaller numbers in one calf fed sporocysts of moose origin could represent either spurious natural infections or indicate low infectivity of Sarcocystis spp. from elk and moose to cattle.     

Climate change impacts population dynamics and distribution shift of moose (Alces alces) in Heilongjiang Province of China

The earth is experiencing obvious climate warming, which may impact population dynamics and the distribution of moose (Alces alces). In this study, we examined the effects of density dependence, temperature, snow depth, and the vegetation (NDVI) on the population dynamics of moose in Heilongjiang Province of China using historical data. Our results demonstrated that moose distribution had continued to contract from the 1980s to the 1990s; moose densities and late spring temperatures in the 1980s were negatively correlated to the rate of increase of the moose population; low and high snow depths in the 1990s showed positive and negative effects, respectively, on the rate of population increase; and the effect of NDVI in the 1980s was similar to the effect of snow depth. Therefore, we confirmed that moose population dynamics is influenced both by intrinsic density-dependent and extrinsic habitat factors, especially late spring temperatures. In addition, an increase in late spring temperatures may shift the southern limit of the distribution of the moose northwards, or may isolate the southernmost portion of the moose population because the rate of warming is higher to the north of a present latitudinal constriction in range than it is at the latitude of the southernmost moose.     

Identification of Sarcocystis hominis-like (Protozoa: Sarcocystidae) cyst in water buffalo (Bubalus bubalis) based on 18S rRNA gene sequences

DNA templates were extracted from isolates of Sarcocystis hominis-like cysts collected from cattle and water buffalo, as well as from Sarcocystis fusiformis cysts and Sarcocystis suihominis cysts. The 18S rRNA genes were amplified using DNA from a single cyst as the templates. Approximately 1,367-1,440 bp sequences were obtained. The sequence difference in isolates of Sarcocystis hominis-like cysts from water buffaloes, and isolates of S. hominis cysts from cattle were very low, only about 0.1%, much lower than the lowest value (1.7%) among different species. Combined with their morphological structure, these sequence data indicate that the 4 isolates from cattle and water buffalo might be the same species, i.e., S. hominis, suggesting that both cattle and water buffalo may serve as the intermediate hosts for this parasite. Apparently, this is the first report using a single cyst to do such work and is a useful way to distinguish the Sarcocystis cyst in an intermediate host that may be simultaneously infected by several different Sarcocystis species.     

The toxic dinoflagellate Cochlodinium polykrikoides (Dinophyceae) produces resting cysts

While harmful algal blooms (HABs) caused by the toxic dinoflagellate Cochlodinium polykrikoides have been known to science for more than a century, the past two decades have witnessed an extraordinary expansion of these events across Asia, North America, and even Europe. Although the production of resting cysts and subsequent transport via ships’ ballast water or/and the transfer of shellfish stocks could facilitate this expansion, confirmative evidence for cyst production by C. polykrikoides is not available. Here, we provide visual confirmation of the production of resting cysts by C. polykrikoides in laboratory cultures isolated from North America. Evidence includes sexually mating cell pairs, planozygotes with two longitudinal flagella, formation of both pellicular (temporary) cysts and resting cysts, and a time series of the cyst germination process. Resting cyst germination occurred up to 1 month after cyst formation and 2–40% of resting cysts were successfully germinated in cultures maintained at 18–21 °C. Pellicular cysts with hyaline membranes were generally larger than resting cysts, displayed discernable cingulum and/or sulcus, and reverted to vegetative cells within 24 h to ∼1 week of formation. A putative armored stage of C. polykrikoides was not observed during any life cycle stage in this study. This definitive evidence of resting cyst production by C. polykrikoides provides a mechanism to account for the recurrence of annual blooms in given locales as well as the global expansion of C. polykrikoides blooms during the past two decades.     

Encounter frequencies between GPS-collared wolves (Canis lupus) and moose (Alces alces) in a Scandinavian wolf territory

Over 6,000 GPS fixes from two wolves (Canis lupus) and 30,000 GPS fixes from five moose (Alces alces) in a wolf territory in southern Scandinavia were used to assess the static and dynamic interactions between predator and prey individuals. Our results showed that wolves were closer to some of the moose when inside their home ranges than expected if they had moved independently of each other, and we also found a higher number of close encounters (<500 m) than expected. This suggests that the wolves were actively seeking the individual moose within their territory. Furthermore, the wolves showed a preference for moving on gravel forest roads, which may be used as convenient travel routes when patrolling the territory and seeking areas where the moose are. However, due to the particularly large size of the wolf territory combined with relatively high moose densities, the wolves generally spent a very small proportion of their time inside the home range of each individual moose, and the frequency of encounters between the wolves and any particular moose was very low. We suggest that the high moose:wolf ratio in this large Scandinavian wolf territory compared to that typically occurring in North America, results in a relatively low encounter frequency and a low predation risk for individual moose, as the predation pressure is spread over a high number of prey individuals.     

A Light Microscopic Comparison of The Cysts of Four Species of Sarcocystis Infecting The Domestic Reindeer (Rangifer Tarandus) in Northern Norway

Fresh preparations of micro-isolated sarcocysts from skeletal and cardiac muscle of 12 reindeer were examined by light microscopy. On the basis of cyst structure and cyst wall structure 4 Sarcocystis spp. could be differentiated. New names have been proposed for 2 previously unnamed Sarcocystis spp. of reindeer, and S. grueneri has been redefined. S. rangiferi n. sp. had macroscopic cysts in skeletal muscle measuring 2106×403 µm. The cyst wall protrusions were finger-like and measured 13.2×6.7 µm. The cysts were surrounded by a layer of fibrillar material. S. tarandi n. sp. had micro- to macroscopic cysts primarily in skeletal muscle, but a few cysts were found in the heart of one animal. In skeletal muscle the cysts measured 999×75µm; in the heart the cysts were shorter and wider. The cyst wall protrusions were fingerlike and measured 9.2×2.2 µm. S. grueneri had micro- to macroscopic cysts in cardiac muscle measuring 581×137 µm. The cyst wall was thin and relatively smooth with no visible protrusions. Sarcocystis sp. had micro- to macroscopic, slender cysts in skeletal muscle measuring 916×64 µm. The cyst wall had tightly packed, short, knob-like protrusions. The cysts of this species were previously classified as cysts of S. grueneri.     

CONTROL OF GERMINATION OF ALEXANDRIUM TAMARENSE (DINOPHYCEAE) CYSTS FROM THE LOWER ST. LAWRENCE ESTUARY (CANADA)

Cysts of the toxic dinoflagellate Alexandrium tamarense (Lebour) Balech 1992 from the lower St. Lawrence estuary were used in a test of the following hypotheses: (1) cyst germination is triggered by a change in temperature, and (2) germination rate varies throughout the year and is controlled by a circannual internal biological clock. Results show that cyst germination was not affected significantly by temperature of incubation over the range 1°–16° C, and light showed no significant stimulation of germination. This is supported by the lack of effect of cyst incubation conditions during evaluation of the seasonal changes in germination rate (two temperatures: 4° and 15° C, and two light conditions: darkness and 150 μmol photons·m^?2·s^?1). Thus, direct environmental control through short-term increases in temperature and exposure to light has no effect on the germination of the cysts tested. The rate of germination, observed monthly over a 16-month period, showed low germination (<20%) over most of the period tested, except for a maximum reaching more than 50% germination in August to October of the second year of the experiment. This pattern was observed for cysts both from monthly field collections and from laboratory-stored cysts kept under constant environmental conditions (4° C, in the dark). The peak in germination observed under constant environmental conditions (in the laboratory), the almost coincidental increase in cyst germination observed for the field-collected cysts, and the absence of effects of temperature and light during incubation could be explained either by a temperature-controlled cyst maturation period (the time-temperature hypothesis of Huber and Nipkow 1923) or by the presence of an internal biological clock. However, the large decline in the rate of germination 2 months after the maximum provides strong support for the biological clock hypothesis. The ca. 12-month maturation (dormancy) period observed for the laboratory-stored cysts is the longest reported for this species to our knowledge; this might be related to the low storage temperature (4° C), which is close to bottom temperatures generally encountered in this environment (0° to 6° C). Similar field and laboratory storage temperatures could explain the coincidental increase in germination rate in the fall of the second year if cyst maturation is controlled by temperature. A fraction of the laboratory-stored cysts did not follow a rhythmic pattern: A rather constant germination rate of about 20% was observed throughout the year. This continuous germination of likely mature cysts may supplement the local blooms of this toxic dinoflagellate, as these often occur earlier than peak germination observed in late summer. It seems that two cyst germination strategies are present in the St. Lawrence: continuous germination after cyst maturation, with temperature controlling the length of the maturation period, and germination controlled by a circannual internal rhythm.     

Rumen Ciliate Fauna of Alaskan Moose (Alces americana), Musk-Ox (Ovibos moschatus) and Dall Mountain Sheep (Ovis dalli)*

Total numbers, generic distribution and percentage species distribution were determined for the ciliate protozoa in rumen contents obtained from Alaskan moose (Alces americana), musk-ox (Ovibos moschatus) and Dall mountain sheep (Ovis dalli). The musk-ox has a fauna somewhat similar to that previously observed in reindeer and caribou. In contrast, only protozoa in the genus Entodinium were observed in moose, while Dall mountain sheep have a fauna unique among Alaskan ruminants studied to date. Other than Entodinium exiguum which was common to all animals, only 2 additional species of Entodinium, observed in the moose and musk-ox, occurred in more than one animal species. Four new species of protozoa are described, Entodinium dalli sp.n., Entodinium constrictum sp.n. and Polyplastron alaskum sp.n. from the Dall mountain sheep and Entodinium alces sp.n. from moose.