Mass mortality in endangered fan musselsPinna nobilis(Linnaeus 1758) caused by co-infection ofHaplosporidium pinnaeand multipleVibrioinfection in Çanakkale Strait, Turkey

Künili, İbrahim Ender; Gürkan, Selin Ertürk; AKSU, Ata; Turgay, Emre; Çakır, Fikret; Gürkan, Mert; Altınağaç, Uğur

doi:10.1080/1354750x.2021.1910344

Cited by 30 publications

(25 citation statements)

References 37 publications

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“…Additionally, the Gram (−) bacterium Vibrio mediterranei, previously described as an opportunistic emerging pathogen associated with mortalities in the wild (Rodrıguez et al, 2017), has again been detected in natural and stabled fan mussels (Prado et al, 2020a;Andree et al, 2021;Lattos et al, 2021). Nowadays, co-infection with H. pinnae and bacteria of various Vibrio spp., has been proposed as the cause of the MME in the Çanakkale Strait (Turkey) (Künili et al, 2021). The more recent findings could suggest a more complex scenario than that originally proposed in the first descriptions of the P. nobilis MMEs.…”

Section: Introductionmentioning

confidence: 89%

Wide-Geographic and Long-Term Analysis of the Role of Pathogens in the Decline of Pinna nobilis to Critically Endangered Species

et al. 2022

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A mass mortality event (MME) affecting the fan mussel Pinna nobilis was first detected in Spain in autumn 2016 and spread north- and eastward through the Mediterranean Sea. Various pathogens have been blamed for contributing to the MME, with emphasis in Haplosporidium pinnae, Mycobacterium sp. and Vibrio spp. In this study, samples from 762 fan mussels (necropsies from 263 individuals, mantle biopsies from 499) of various health conditions, with wide geographic and age range, taken before and during the MME spread from various environments along Mediterranean Sea, were used to assess the role of pathogens in the MME. The number of samples processed by both histological and molecular methods was 83. The most important factor playing a main role on the onset of the mass mortality of P. nobilis throughout the Mediterranean Sea was the infection by H. pinnae. It was the only non-detected pathogen before the MME while, during MME spreading, its prevalence was higher in sick and dead individuals than in asymptomatic ones, in MME-affected areas than in non-affected sites, and it was not associated with host size, infecting both juveniles and adults. Conversely, infection with mycobacteria was independent from the period (before or during MME), from the affection of the area by MME and from the host health condition, and it was associated with host size. Gram (-) bacteria neither appeared associated with MME.

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Section: Introductionmentioning

confidence: 89%

Wide-Geographic and Long-Term Analysis of the Role of Pathogens in the Decline of Pinna nobilis to Critically Endangered Species

et al. 2022

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“…The proposed mechanism for maintaining such a high diversity is based on either the advantage of heterozygotes (i.e., overdominance), the advantage of rare alleles (90,91), fluctuating selection (89,92) or a combination thereof. In our study, the high haplotype diversity observed at some TLRs might likely be induced and maintained by these three mechanisms, most probably by the fluctuating selection (39,(41)(42)(43). Moreover, we did not find any sign of heterozygous advantage associated to the resistance to H. pinnae .…”

Section: Assessment Of Selection Towards Tlr Locimentioning

confidence: 40%

“…In our study, we observed on the contrary a high number of haplotypes of the vesicular TLR-7, which binds single stranded RNA. This discrepancy could be consistent with a relaxed selection acting at this locus, reflecting the high diversity of intra-cellular pathogens that could possibly be encountered in the environment (39,41). To our knowledge, the diversity of TLR-7 has not been described in bivalves, and a high level of TLR-7 has just been observed in chicken (80,81).…”

Section: Variation Of Tlr Genesmentioning

confidence: 58%

“…Unfortunately, the species has been experiencing mass mortality events (MME) since 2016, attributed to a multifactorial disease mainly conveyed to the protozoan parasite Haplospordium pinnae , but also to the bacteria Vibrio mediterranei and Mycobaterium sp., among potentially yet uncharacterized other pathogens, such as viruses and micro-eukaryotes (39)(40)(41)(42). These MME led to dramatic demographic bottlenecks, throughout the species distribution area (39,(43)(44)(45), that are expected to critically reduce the genetic diversity, increase population fragmentation, and probably negatively influence the natural rescue effect through larval connectivity, due to reduced reproduction success (46).…”

Section: Introductionmentioning

confidence: 99%

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The characterization of toll-like receptor repertoire in Pinna nobilis after mass mortality events suggests adaptive introgression.

Coupé

Prévot

Giantsis

et al. 2022

Preprint

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The fan mussel Pinna nobilis is currently on the brink of extinction due to a multifactorial disease mainly caused to the highly pathogenic parasite Haplosporidium pinnae, meaning that the selection pressure outweighs the adaptive potential of the species. Hopefully, rare specimens have been observed somehow resistant to the parasite, stretching the need to identify the traits underlying this better fitness. Among the candidate to explore at first intention are fast evolving immune genes, of which toll-like receptor (TLR). In this study, we examined the genetic diversity at 14 TLR loci across Pinna nobilis, Pinna rudis and Pinna nobilis x Pinna rudis hybrid genomes, collected at four physically distant regions, that were found to be either resistant or sensitive to the parasite Haplosporidium pinnae. We report a high genetic diversity, mainly observed at cell surface TLRs compared to that of endosomal TLRs. However, the TLR-7 and TLR-1 exhibited unexpected level of diversity and haplotype phylogeny, respectively. The lack of population structure, associated with a high genetic diversity and elevated dN/dS ratio were interpreted as balancing selection, though both directional and purifying selection were detected. Overall, we observed small contributions of putatively selected SNPs involved in the resistance. However, the most contributing SNPs were carried by two TLR-6 loci and might be used as potent biomarkers of distinguish between resistant and sensitive P. nobilis individuals. Moreover, more than 10% of P. nobilis individuals were found introgressed with P. rudis. Noteworthy, all introgressed P. nobilis observed as resistant to H. pinnae carried a TLR-7 of P. rudis origin. This study contributes to the ongoing efforts towards conservation carried out to prevent from extinction this Mediterranean endemic species.

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“…Recently, researchers agreed on the main reason for the mass mortality of P. nobilis, is the parasite H. pinnae (Caballero 2021;Künili et al 2021;IUCN 2021). Environmental factors, especially, temperature (over 13.5 o C) and salinity (36.5-39.7 PSU) have also been declared as triggers for the mass mortality incidents (Cabanellas-Reboredo et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Mass mortality report of the critically endangered Pinna nobilis (Linnaeus, 1758) in Gökçeada (North Aegean Sea, Turkey)

Acarlı

Öz

2022

EgeJFAS

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In August 2020, a total area of 38000 m2 around Gökçeada has been scanned to determine the current population status of Pinna nobilis. 9 stations (Yıldızkoy, Manastır, Marmaros, Gizli Liman, Laz Koyu, Kapıkaya, Karaçavuş, Karaçavuş shore and Kefalos) have been detected by means of SCUBA and ABC diving techniques. All specimens were found dead (total mass mortality of 100%). The total length range of P. nobilis was between 30.8 – 38.3 cm.

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Mass mortality in endangered fan musselsPinna nobilis(Linnaeus 1758) caused by co-infection ofHaplosporidium pinnaeand multipleVibrioinfection in Çanakkale Strait, Turkey

Cited by 30 publications

References 37 publications

Wide-Geographic and Long-Term Analysis of the Role of Pathogens in the Decline of Pinna nobilis to Critically Endangered Species

Wide-Geographic and Long-Term Analysis of the Role of Pathogens in the Decline of Pinna nobilis to Critically Endangered Species

The characterization of toll-like receptor repertoire in Pinna nobilis after mass mortality events suggests adaptive introgression.

Mass mortality report of the critically endangered Pinna nobilis (Linnaeus, 1758) in Gökçeada (North Aegean Sea, Turkey)

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