Ascaridoid Nematodes from the Stomach of Harp Seals, Phoca groenlandica, from Newfoundland and Labrador

1992 ◽  
Vol 49 (5) ◽  
pp. 956-966 ◽  
Author(s):  
John Brattey ◽  
I-Hsun Ni
Keyword(s):  
Newfoundland And Labrador ◽  
Sex Ratios ◽  
Condition Index ◽  
Fish Stocks ◽  
Phoca Groenlandica ◽  
Pseudoterranova Decipiens ◽  
Large Numbers ◽  
Pinniped Species ◽  
Nematode Abundance ◽  
Contracaecum Osculatum

Stomachs of 488 harp seals, Phoca groenlandica, collected off Newfoundland and Labrador during 1984–88, contained four species of ascaridoid nematodes. Seals had high prevalences and abundances of Contracaecum osculatum B and Phocascaris sp. but were rarely infected with Anisakis simplex B or Pseudoterranova decipiens B (sealworm). Nematode abundance increased with age, and distribution of each species among seals was highly aggregated. Gastric lesions, often associated with clusters of nematodes, occurred in 13.8% of 405 seals. Female seals with large numbers of nematodes had a higher body condition index (sculp weight) than lightly infected females. Overall sex ratios of C. osculatum B and Phocascaris sp. were biased toward females, but sex ratios of adult nematodes among individual seals were heterogeneous. Most nematodes recovered were third- or fourth-stage larvae; adults of C. osculatum B and Phocascaris sp. were also common, but no mature females of A. simplex B or P. decipiens B were found. Harp seals are probably unimportant in the transmission of A. simplex but may be partly responsible for sealworm found in fish stocks off Newfoundland and Labrador. More information on other pinniped species is needed to assess more precisely the relative importance of harp seals in sealworm transmission.

Host specificity and abundance of parasitic nematodes (Ascaridoidea) from the stomachs of five phocid species from Newfoundland and Labrador

1993 ◽  
Vol 71 (11) ◽  
pp. 2156-2166 ◽  
Author(s):  
John Brattey ◽  
Garry B. Stenson
Keyword(s):  
Newfoundland And Labrador ◽  
Phoca Vitulina ◽  
Halichoerus Grypus ◽  
Parasitic Nematodes ◽  
Fish Stocks ◽  
Cystophora Cristata ◽  
Pseudoterranova Decipiens ◽  
Large Numbers ◽  
Harbour Seals ◽  
Contracaecum Osculatum

Stomachs of 270 phocids from five species (bearded, Erignathus barbatus; hooded, Cystophora cristata; grey, Halichoerus grypus; harbour, Phoca vitulina; and ringed, P. hispida), collected off Newfoundland and Labrador during 1985–1993 were examined, and the numbers and percentages of larval and adult ascaridoid nematodes determined. Samples of adult nematodes were also identified using previously described allozymes. Bearded seals were infected mainly with Contracaecum osculatum A, C. osculatum B, and Pseudoterranova decipiens C, whereas hooded seals harboured mostly Phocascaris spp. Grey seals harboured large numbers of C. osculatum B, and small numbers of adult Anisakis simplex; harbour and grey seals were the only phocids heavily infected with P. decipiens B. Ringed seal stomachs contained fewer nematodes than other seal species and were mainly infected with C. osculatum B and Phocascaris spp. In several seal species positive, but no negative, associations in abundance were observed between nematodes. Sex ratios of adult nematodes among individual seals were heterogeneous, but changes in sex ratio suggest a bias towards female nematodes among larvae infecting fish and a selective loss of adult females during maturation. Overall, the results suggest that grey and harbour seals are the main source of larval sealworm (P. decipiens B) occurring in fish stocks off Newfoundland and Labrador, although small numbers of adult P. decipiens B also occurred in hooded seals.

scholarly journals Distribution and abundance of sealworm (Pseudoterranova decipiens) and other anisakid nematodes in fish and seals in the Gulf of St. Lawrence: potential importance of climatic conditions

2001 ◽  
Vol 3 ◽  
pp. 113 ◽  
Author(s):  
David J Marcogliese
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Climatic Conditions ◽  
Pseudoterranova Decipiens ◽  
Nematode Abundance ◽  
Contracaecum Osculatum ◽  
Myoxocephalus Scorpius ◽  
Longhorn Sculpin ◽  
Anisakid Nematodes ◽  
Seal Diet

Prevalence and abundance of sealworm (Pseudoterranova decipiens) and other anisakid nematodes were determined in a variety of fishes from the Gulf of St. Lawrence in 1990 and 1992. Sealworm abundance and prevalence were also determined in three species of seals in the Gulf between 1988 and 1992. Atlantic cod (Gadus morhua) and shorthorn (Myoxocephalus scorpius) and longhorn sculpin (M. octodecemspinosus) were the fishes most heavily infected with sealworm. Grey seals(Halichoerus grypus) proved to be the most important definitive hosts for sealworm in the Gulf. Abundance of sealworm increased, whereas that of Anisakis simplex and contracaecine nematodes decreased, from north to south in the Gulf. Abundance of sealworm increased compared to earlier surveys in most areas of the Gulf, but decreased in both cod and grey seals during the course of this study. In contrast, abundance of Contracaecum osculatum and Phocascaris spp. in grey seals and cod continued to increase during the study period. Observed increases of nematodes are attributed to growing populations of grey seals (for sealworm) and harp seals (for Contracaecinea). Levels of A. simplex remained relatively constant between 1988 and 1992 in both grey seals and cod. There is no evidence suggesting that observed patterns in nematode abundance were due to changes in grey seal diet. Nor was there any evidence of competition between P. decipiens and C. osculatum in grey seals affecting either sealworm abundance or fecundity. The trends detected herein are attributed to climatic events in the Gulf of St. Lawrence, where water temperatures in the cold intermediate layer consistently decreased between 1986 and 1994. It is suggested that low temperatures inhibited development and hatching of sealworm eggs, but not those of C. osculatum.

scholarly journals Contracaecum osculatumand other anisakid nematodes in grey seals and cod in the Baltic Sea: molecular and ecological links

2017 ◽  
Vol 92 (1) ◽  
pp. 81-89 ◽  
Author(s):  
S. Zuo ◽  
P.W. Kania ◽  
F. Mehrdana ◽  
M.H. Marana ◽  
K. Buchmann
Keyword(s):  
Baltic Sea ◽  
Gadus Morhua ◽  
Final Host ◽  
The Baltic Sea ◽  
Fish Stocks ◽  
Pseudoterranova Decipiens ◽  
Contracaecum Osculatum ◽  
The Baltic ◽  
The Impact ◽  
Anisakid Nematodes

AbstractPopulations of grey seals (Halichoerus grypus), sprats (Sprattus sprattus) and cod (Gadus morhua) in the Baltic Sea are relatively stationary. The present work, applying classical and molecular helminthological techniques, documents that seals and cod also share a common parasite, the anisakid nematodeContracaecum osculatum, which uses seals as the final host and fish as transport hosts. Sequencing mitochondrial genes (COX1andCOX2) in adult worms from seals and third-stage larvae from livers of Baltic fish (sprats and cod), showed that all gene variants occur in both seals and fish. Other anisakid nematodesPseudoterranova decipiensandAnisakis simplexare also found in both seals and cod in the Baltic Sea, but at much lower rates. The Baltic grey seal population was left at a critically low level (comprising a few hundred individuals) during the latter part of the 20th century, but since the year 2000 a marked increase in the population has been observed, reaching more than 40,000 individuals at present. Ecological consequences of the increased seal abundance may result from increased predation on fish stocks, but recent evidence also points to the influence of elevated parasitism on fish performance.Contracaecum osculatumlarvae preferentially infect the liver of Baltic cod, considered a vital organ of the host. Whereas low prevalences and intensities in cod were reported during the 1980s and 1990s, the present study documents 100% prevalence and a mean intensity of above 80 worms per fish. Recent studies have also indicated the zoonotic potential ofC. osculatumlarvae in fish, following the consumption of raw or under-cooked fish. Therefore the present work discusses the impact of parasitism on the cod stock and the increasing risk for consumer health, and lists possible solutions for control.

Repetition enhances hearing detection thresholds in a harbour seal (Phoca vitulina)

1993 ◽  
Vol 71 (5) ◽  
pp. 926-932 ◽  
Author(s):  
S. D. Turnbull ◽  
J. M. Terhune
Keyword(s):  
White Noise ◽  
Background Noise ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Detection Thresholds ◽  
Noise Masking ◽  
Phoca Groenlandica ◽  
Hearing Thresholds ◽  
Lower Detection ◽  
Pinniped Species

Pure-tone hearing thresholds of a harbour seal (Phoca vitulina) were measured in air and underwater using behavioural psychophysical techniques. A 50-ms sinusoidal pulse was presented in both white-noise masked and unmasked situations at pulse repetition rates of 1, 2, 4, and 10/s. Test frequencies were 0.5, 1.0, 2.0, 4.0, and 8.0 kHz in air and 2.0, 4.0, 8.0, and 16.0 kHz underwater. Relative to 1 pulse/s, mean threshold shifts were −1, −3, and −5 dB at 2, 4, and 10 pulses/s, respectively. The threshold shifts from 1 to 10 pulses/s were significant (F = 12.457, df = 2,36, p < 0.001) and there was no difference in the threshold shifts between the masked and unmasked situations (F = 2.585; df = 1,50; p > 0.10). Broadband masking caused by meteorological or industrial sources will closely resemble the white-noise situation. At high calling rates, the numerous overlapping calls of some species (e.g., harp seal, Phoca groenlandica) present virtually continous "background noise" which also resembles the broadband white-noise masking situation. An implication of lower detection thresholds is that if a seal regularly repeats short vocalizations, the communication range of that call could be increased significantly (80% at 10 pulses/s). This could have important implications during the breeding season should storms or shipping noises occur or when some pinniped species become increasingly vocal and the background noise of conspecifics increases.

Anisakids of seals found on the southern coast of Baltic Sea

2014 ◽  
Vol 59 (1) ◽  
Author(s):  
Michał Skrzypczak ◽  
Jerzy Rokicki ◽  
Iwona Pawliczka ◽  
Katarzyna Najda ◽  
Joanna Dzido
Keyword(s):  
Baltic Sea ◽  
Life Stage ◽  
Adult Life ◽  
Sensu Stricto ◽  
Halichoerus Grypus ◽  
Slight Excess ◽  
Pseudoterranova Decipiens ◽  
Pusa Hispida ◽  
Contracaecum Osculatum ◽  
Anisakid Nematodes

AbstractIn the present study 5 grey seals (Halichoerus grypus), 3 common seals (Phoca vitulina) and 1 ringed seal (Pusa hispida) bycaught or stranded on the Polish Baltic Sea coast in years 2000-2006 were investigated for the infestation of parasitic anisakid nematodes. 749 of anisakids were found. The most common were: Contracaecum osculatum (59.3%) and Pseudoterranova decipiens (31.0%). There were also small numbers of Anisakis simplex (0.8%). After performing RFLP three sibling species were found. C. osculatum was identified as C. osculatum C, P decipiens was identified as P. decipiens sensu stricto and A. simplex — A. simplex sensu stricto. Nematodes found in seals were mostly in L4 and adult life stage — both of them were equal with some minor variations among the specimens. Sex ratio was also equal, but there was slight excess of males in some cases. There was a minority of L3 larvae belonging to A. simplex species (0.8%).

scholarly journals Molecular studies on larvae of Pseudoterranova parasite of Trichiurus lepturus Linnaeus, 1758 and Pomatomus saltatrix (Linnaeus, 1766) off Brazilian waters

2015 ◽  
Vol 60 (4) ◽  
Author(s):  
Juliana N. Borges ◽  
Luiz F. G. Cunha ◽  
Daniele F. Miranda ◽  
Cassiano Monteiro-Neto ◽  
Cláudia P. Santos
Keyword(s):  
Atlantic Coast ◽  
Genetic Profile ◽  
Pomatomus Saltatrix ◽  
Generic Level ◽  
Southwest Atlantic ◽  
Molecular Approaches ◽  
Pseudoterranova Decipiens ◽  
Trichiurus Lepturus ◽  
Contracaecum Osculatum ◽  
Cox 1

AbstractPseudoterranova larvae parasitizing cutlassfish Trichiurus lepturus and bluefish Pomatomus saltatrix from Southwest Atlantic coast of Brazil were studied in this work by morphological, ultrastructural and molecular approaches. The genetic analysis were performed for the ITS2 intergenic region specific for Pseudoterranova decipiens, the partial 28S (LSU) of ribosomal DNA and the mtDNA cox-1 region. We obtained results for the 28S region and mtDNA cox-1 that was amplified using the polymerase chain reaction and sequenced to evaluate the phylogenetic relationships between sequences of this study and sequences from the GenBank. The morphological profile indicated that all the nine specimens collected from both fish were L3 larvae of Pseudoterranova sp. The genetic profile confirmed the generic level but due to the absence of similar sequences for adult parasites on GenBank for the regions amplifyied, it was not possible to identify them to the species level. The sequences obtained presented 89% of similarity with Pseudoterranova decipiens (28S sequences) and Contracaecum osculatum B (mtDNA cox-1). The low similarity allied to the fact that the amplification with the specific primer for P. decipiens didn´t occur, lead us to conclude that our sequences don’t belong to P. decipiens complex.

scholarly journals Anisakis physeteris and Pseudoterranova decipiens in the Mugil curema fish caught in Tumaco, Colombia

2020 ◽  
pp. e1781
Author(s):  
Jenniffer Alejandra Castellanos Garzon ◽  
Rubén Mercado P ◽  
Sebastián Peña F ◽  
María Carolina Pustovrh R ◽  
Liliana Salazar M
Keyword(s):  
Sensu Stricto ◽  
Anisakis Simplex ◽  
Anisakis Pegreffii ◽  
Pseudoterranova Decipiens ◽  
Pcr Multiplex ◽  
Contracaecum Osculatum ◽  
Hysterothylacium Aduncum ◽  
Anisakis Physeteris

Objetivo. Identificar nematodos de la familia Anisakidae en el pez de consumo Mugil curema. Materiales y métodos. Para este estudio, se recolectaron 16 peces Lisa (M. curema) del puerto de Tumaco, una ciudad en la costa colombiana del Pacífico. La identificación morfológica de las larvas se realizó mediante taxonomía clásica y se calculó el porcentaje de infestación de larvas. Para la identificación molecular, se realizó una PCR múltiple con cebadores para las especies Anisakis physeteris, Pseudoterranova decipiens, Anisakis simplex sensu stricto, Contracaecum osculatum, Hysterothylacium aduncum y Anisakis pegreffii. Resultados. La revisión taxonómica permitió la identificación de larvas de tipo II del género Anisakis y larvas del género Pseudoterranova. Las larvas se aislaron principalmente del intestino, donde se encontró que el 94% de los peces estaban parasitados por nematodos anisakidos. La PCR multiplex permitió la identificación de la especie A. physeteris (Larva tipo II) y P. decipiens. Conclusiones. Este estudio en el primer reporte del nematodo Anisakidae en Tumaco, Colombia. Estos resultados proporcionan una justificación convincente para un estudio adicional sobre la familia Anisakidae en Colombia, como un problema de salud pública.

Abundance and maturity of three species of parasitic anisakine nematodes (Pseudoterranova decipiens, Contracaecum osculatum, Anisakis simplex) occurring in Sable Island harbour seals (Phoca vitulina)

2002 ◽  
Vol 80 (3) ◽  
pp. 442-449 ◽  
Author(s):  
Wayne T Stobo ◽  
L Paul Fanning ◽  
Brian Beck ◽  
G Mark Fowler
Keyword(s):  
Prey Species ◽  
Phoca Vitulina ◽  
Final Host ◽  
Anisakis Simplex ◽  
Halichoerus Grypus ◽  
Commercial Fish ◽  
Pseudoterranova Decipiens ◽  
Harbour Seals ◽  
Seal Population ◽  
Contracaecum Osculatum

Three species of anisakine nematodes (Pseudoterranova decipiens, Contracaecum osculatum, Anisakis simplex) co-occur in the stomachs of Sable Island harbour seals (Phoca vitulina). The sealworm, P. decipiens, was the commonest nematode in these seals. Anisakis simplex was found in much smaller numbers, none mature, indicating that the harbour seal is not a true final host to this parasite. Contracaecum osculatum was rare but half were mature. Pseudoterranova decipiens increased in abundance with size of the seal. An inverse relationship was observed between P. decipiens abundance and the age of seals of similar size, probably owing to changes in diet. Numbers of P. decipiens may have declined over the summer, coincident with an increase in the proportion of mature worms in the stomach. From similarities between the worm infections of grey seals (Halichoerus grypus) and harbour seals, we infer that A. simplex abundance may also exhibit a decline in abundance. Contracaecum osculatum was only encountered during the latter half of the year, suggesting an association with prey species of corresponding periodicity in their distribution. We estimate that the abundance of sealworm in harbour seals is about 2.5% of that carried by the grey seal population. This could imply that harbour seals represent an insignificant vector of the sealworm infecting commercial fish species in the Northwest Atlantic, provided density-dependent relationships exist between worm abundances in different host species.

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