Paralithodes Platypus Research Articles

Синий краб Paralithodes platypus – востребованный объект крабового промысла в северо-западной части Охотского моря (в Северо-Охотоморской подзоне)

The history of the study and fishing, the main biological indicators of the blue king crab Paralithodes platypus, living in the north-western part of the Sea of Okhotsk, are considered. Based on the materials collected in 2003-2022, the course of fishing and catching of this crab is analyzed. It is shown that the prospects of industrial development of this valuable object in the coming years do not cause concerns.

A scientometric review of climate change and research on crabs

Crabs categorized as cold-blooded organisms are especially at risk as climate change worsens. Their current situation was not well documented, especially in terms of scientometric analysis. The present study aims to investigate the relationship between research on crabs and climate change-related studies, with a focus on identifying trends and hotspots over time. The analysis was based on a collection of over 2834 relevant documents and 107,502 cited references indexed in the Web of Science Core Collection (WOSCC) database from 1977 to 2022. The findings indicated an increase in research in recent decades, with the USA as the largest contributor, followed by China and Brazil. Researchers from the USA and Germany were among the top published authors in the field. The most highly cited studies in WOSCC focused on the relationship between harmful algal blooms and crab research. Of these studies, 20 clusters were generated, with the most influential cluster identified as related to “ocean acidification,” “blue king crab,” and “mud crab fishery.” The most frequently cited and influential keywords in the field were “climate change” and “hypoxia,” respectively. Our conclusion is that the fields of “research on crabs” and “climate change” are thriving and that further exploration of the adaptation strategies of these organisms is necessary. This knowledge will benefit scientific communities, philanthropic funders or related governments, fisheries-related industries, and NGOs towards the sustainable management of commercial crab species in the future.

Whole genome evaluation analysis and preliminary Assembly of Oratosquilla oratoria (Stomatopoda: Squillidae)

As the dominant species of Stomatopoda, Oratosquilla oratoria has not been fully cultivated artificially, and the fishery production mainly depends on marine fishing. Due to the lack of stomatopod genome, the development of molecular breeding of mantis shrimps still lags behind. A survey analysis was performed to obtain the genome size, GC content and heterozygosity ratio in order to provide a fundation for subsequent whole-genome sequencing. The results showed that the estimated genome size of the O. oratoria was about 2.56 G, and the heterozygosity ratio was 1.81%, indicating that it is a complex genome. Then the sequencing data was preliminarily assembled with k-mer = 51 by SOAPdenovo software to obtain a genome size of 3.01G and GC content of 40.37%. According to ReapeatMasker and RepeatModerler analysis, the percentage of repeats in O. oratoria was 45.23% in the total genome, similar to 44% in Survey analysis. The MISA tool was used to analyze the simple sequence repeat (SSR) characteristics of genome sequences including Oratosquilla oratoria, Macrobrachium nipponense, Fenneropenaeus chinensis, Eriocheir japonica sinensis, Scylla paramamosain and Paralithodes platypus. All crustacean genomes showed similar SSRs characteristics, with the highest proportion of di-nucleotide repeat sequences. And AC/GT and AGG/CCT repeats were the main types of di-nucleotide and tri-nucleotide repeats in O. oratoria. This study provided a reference for the genome assembly and annotation of the O. oratoria, and also provided a theoretical basis for the development of molecular markers of O. oratoria.

The Population Dynamics of the Blue Crab (Paralithodes platypus Brandt, 1849) in the Northwestern Bering Sea

The Population Dynamics of the Blue Crab (Paralithodes platypus Brandt, 1849) in the Northwestern Bering Sea

Size of maturity for blue king crab Paralithodes platypus in the northern part of the Sea of Okhotsk

We determined the size of sexual maturity of male and female blue crabs in the northwestern part of the sea (zone of cold core action), as well as in the northeastern part of the sea and the local cluster near the Iona bank (zone of comparatively warm waters). Morphological 50% maturation of males in the northwestern part of the Sea of Okhotsk was observed at the carapace width of 73.3 mm. Similar width were demonstrated for the northeastern part of the sea and for the Iona Bank area – respectively 88.5 mm and 91.0 mm. Females in samples from the northwestern part of the sea reached functional 50% maturity at the carapace width of 71.7 mm, from the northeastern part – of 79.4 mm, and from the Iona Bank – of 81.0 mm. Comparison with available literature data showed that blue crab in the northwestern part of the Sea of Okhotsk has probably the slowest growth rate, and the crabs have the smallest size at maturity compared to individuals in the other areas.

Growth Features of Blue King Crab Paralithodes platypus in the Northern Part of the Sea of Okhotsk

Growth Features of Blue King Crab Paralithodes platypus in the Northern Part of the Sea of Okhotsk

Dynamics of indices of the state of the blue king crab stock in the western part of the Bering Sea in 2005–2021

The aim of the research is a retrospective analysis of the stock of the blue king crab Paralithodes platypus inhabiting the western part of the Bering Sea, to show the prospects of using the relative abundance index (I%N) as an assessment characterizing the state of the stock of this species. Material and methods. It is based on the data of direct accounting of P. platypus during trawl and trap surveys in 2005–2021. For each year, an index of relative abundance was established, expressed as a percentage of the maximum number of crabs noted in the retrospective period. The I%N index was determined for different functional groups of the crab separately and for combined size and age groups. New data. The use of the relative abundance index I%N in quartiles makes it possible to apply a four-zonal evaluation characteristic of the stock status of P. platypus: the stock condition is good, satisfactory, uncertain and depressive. This indicative method displays the dynamics of the state of the stock in the studied period and visualizes its variability in the historical period. In the West Bering Sea population of P. platypus, there has recently been a decrease in the number, which is less than 40 % of the maximum number observed during the study period. In all functional groups of P. platypus, the estimate of abundance (stock) is currently characterized as uncertain. Practical significance. The retrospective dynamics of the relative abundance index I%N is an additional operational indicator in making a management decision when developing P. platypus as a commercial reserve unit in the western part of the Bering Sea.

Intraspecific morphological variability of blue king crab in the northern part Sea of Okhotsk

The results in the water area from island Big Shantar to the Babushkina bay points to the existence of morphometric differences in the blue crab from the northern part of the Sea of Okhotsk. The proportions of the crab’s body change statistically significantly: in the direction from the west (severe hydrological regime) to the east (relatively warm area) crabs become more elongated in width, the right claw in all measured parameters and the height of the left claw decrease relative to the width of the carapace, and there was also a decrease in the length of the merus of the first walking leg. With the inclusion of materials from the Shelikhov Bay, in the correlation analysis, in addition to the previously found dependences (associated with the fishing length of the carapace and the height of the right claw), the clinal variability of the length of the second pereopod was also noted: its shortening occurs as in the first pereopod in the direction from west to east. When performing discriminant analysis (the sample from Shelikhov Bay was not included), the most significant morphometric differences were noted between the most remote areas: western and eastern (D2M =2,95–3,72), which, apparently, is a consequence of contrasting environmental conditions.

Relative abundance index as an operational assessment of the state of the king blue crab stock in the Shelikhov Bay of Okhotsk Sea

The material of spring registration surveys of the blue king crab Paralithodes platypus conducted in the Shelikhov Bay of the Okhotsk Sea from 2007 to 2019 is presented. It is proposed to use the relative abundance index (I%N) for a quick assessment of the characterizing state of the stock of the exploited population. The index I%N is defined as the ratio of the number of a separate functional group of the crab to the maximum number for this group of crab in the study period, expressed as a percentage. A similar algorithm was used to determine the index of the relative density of the distribution of crabs (I%P) and the index of the relative average daily catch of fishing vessels for the first half of the year (I%M). When comparing the relative indices I%N, I%P, I%M, the most convincing was the relative population index I%N. To assess the stock status of the studied functional group of crabs in the values of the index I%N, it was proposed to distinguish 4 quartiles (interval 25 units): 1st quartile (Q1) I%N <75 stock condition is good; 2nd quartile (Q2) I%N = 51–75 stock condition is satisfactory or relatively stable; 3rd quartile (Q3) I%N 26–50 stock status uncertain; 4th quartile (Q4) I%N ≤25 stock status is unsatisfactory or depressive. The boundary values between quartiles Q1–Q2, Q2–Q3, and Q3–Q4 are I%N values of 75, 50, and 25, respectively. The dynamics of the I%N index in the studied time period reflects the real process taking place in the fishing unit of the stock based only on empirical data.

Chromosome-level genome assembly of Paralithodes platypus provides insights into evolution and adaptation of king crabs.

The blue king crab, Paralithodes platypus, which belongs to the family Lithodidae, is a commercially and ecologically important species. However, a high‐quality reference genome for the king crab has not yet been reported. Here, we assembled the first chromosome‐level blue king crab genome, which contains 104 chromosomes and an N50 length of 51.15 Mb. Furthermore, we determined that the large genome size can be attributed to the insertion of long interspersed nuclear elements and long tandem repeats. Genome assembly assessment showed that 96.54% of the assembled transcripts could be aligned to the assembled genome. Phylogenetic analysis showed the blue king crab to have a close relationship with the Eubrachyura crabs, from which it diverged 272.5 million years ago. Population history analyses indicated that the effective population of the blue king crab declined sharply and then gradually increased from the Cretaceous and Neogene periods, respectively. Furthermore, gene families related to developmental pathways, steroid and thyroid hormone synthesis, and inflammatory regulation were expanded in the genome, suggesting that these genes contributed substantially to the environmental adaptation and unique body plan evolution of the blue king crab. The high‐quality reference genome reported here provides a solid molecular basis for further study of the blue king crab's development and environmental adaptation.

First record of new rickettsia-like organism in the blue king crab Paralithodes platypus from the Sea of Okhotsk: Distribution, morphological evidence and genetic analysis

An infection caused by a rickettsia-like organism (RLO) was detected in the blue king crab Paralithodes platypus from the eastern Sea of Okhotsk. The external signs of the disease are lethargy and an empty gastrointestinal tract. Dissection of infected individuals revealed that their hepatopancreas was light yellow in color. The causative agent of infection is Gram-negative rod-shaped bacterium targeted exclusively at hepatopancreas tissues. In the cytoplasm of infected cells, the bacteria are enclosed in parasite vacuoles or located immediately in cytosol. An ultrastructural analysis showed two main morphological types corresponding to the life cycle stages in the RLO: the vegetative stage of intermediate bodies, characterized by growth and division processes, and the infection stage of elementary bodies, which are spore-like non-dividing short rods surrounded by a multilayered membrane and having an osmiophilic inclusion body. At the terminal stage of infection, as a result of lysis of the infected cells, the RLO enters the lumen of the hepatopancreatic tubules which contributes to the spread of infection. According to genetic analysis based on 16S rRNA gene sequences, the RLO from P. platypus is most closely related to the Candidatus Hepatobacter penaei, NCBI #JX981946 (94.7% similarity) and NCBI #KY363553 (94.1% similarity). The high level of genetic differences (more than 5%) of the studied pathogen, along with the structural features, allows characterizing the RLO isolated from P. platypus as a new species of the genus Candidatus Hepatobacter paralithodi nov. sp., NCBI #MK928971.

Rapid assessment of management options for promoting stock rebuilding in data-poor species under climate change.

The development of species recovery plans requires considering likely outcomes of different management interventions, but the complicating effects of climate change are rarely evaluated. We examined how qualitative network models (QNMs) can be deployed to support decision making when data, time, and funding limitations restrict use of more demanding quantitative methods. We used QNMs to evaluate management interventions intended to promote the rebuilding of a collapsed stock of blue king crab (Paralithodes platypus) (BKC) around the Pribilof Islands (eastern Bering Sea) to determine how their potential efficacy may change under climate change. Based on stakeholder input and a literature review, we constructed a QNM that described the life cycle of BKC, key ecological interactions, potential climate-change impacts, relative interaction strengths, and uncertainty in terms of interaction strengths and link presence. We performed sensitivity analyses to identify key sources of prediction uncertainty. Under a scenario of no climate change, predicted increases in BKC were reliable only when stock enhancement was implemented in a BKC hatchery-program scenario. However, when climate change was accounted for, the intervention could not counteract its adverse impacts, which had an overall negative effect on BKC. The remaining management scenarios related to changes in fishing effort on BKC predators. For those scenarios, BKC outcomes were unreliable, but climate change further decreased the probability of observing recovery. Including information on relative interaction strengths increased the likelihood of predicting positive outcomes for BKC approximately 5-50% under the management scenarios. The largest gains in prediction precision will be made by reducing uncertainty associated with ecological interactions between adult BKC and red king crab (Paralithodes camtschaticus). Qualitative network models are useful options when data are limited, but they remain underutilized in conservation.

ПРОМЫСЕЛ СИНЕГО КРАБА В ЗАПАДНО-КАМЧАТСКОЙ ПОДЗОНЕ ОХОТСКОГО МОРЯ В 2013–2018 ГГ.

Analysis of the fishery of blue king crab is provided based on collected data. State of blue king crab stock abundance in the West-Kamchatka subzone is evaluated. Character of seasonal distribution of commercial males is analyzed, and plots of the maximum dense aggregations of the crab and periods of the most efficient fishing are figured out. The data obtained in the course of commercial fishery monitoring are used for the quality analysis of the catch composition and evaluation of the CPUE. Size-frequevcy distribution of blue king crab males is analyzed comparing to the data pools of previous years.

SIZE COMPOSITION AND GROWTH RATES OF BLUE KING CRAB PARALITHODES PLATYPUS BRANDT, 1850 IN THE RUSSIAN SECTOR OF THE BERING SEA

Size composition and growth rate of blue king crab males are analyzed on the data of 8 bottom trawl surveys conducted in the western Bering Sea in summer-fall seasons within the period from 2005 to 2017. Significant changes in size structure of this population are revealed. Portion of commercial males was the lowest (18.7 %) in 2010 because of the strong yearclass appeared in the catches in 2005, when its males carapace had the width 20–40 mm, that provided in 2008–2010 the percentage of juveniles with the size < 100 mm about 59–60 %. Then this strong year-class reached the commercial size, so the portion of commercial males increased to 66 % in 2014 and to 85 % in 2015–2016. The portion of juveniles was extremely small (3.1–6.5 %) in these years. The portion of commercial males had reduced again to 67 % in 2017 because of a new strong year-class appearance that provided the juveniles percentage increasing to 24.6 %. The mean size of commercial males has increased since 2012 in 18 mm and reached the value of 160.4 mm in 2017. Age of the crab males entry into the commercial cohort is estimated as 8 years. The observed cyclic changes in size composition of blue king crab and estimated value of its growth rate indicate indirectly a good and stable state of its population in the western Bering Sea.

Плодовитость синего краба в северной части Охотского моря

Плодовитость синего краба в северной части Охотского моря

Pitanie sinego kraba Paralithodes platypus v zalive Babushkina Okhotskoe more v iyule 2011 g

Pitanie sinego kraba Paralithodes platypus v zalive Babushkina Okhotskoe more v iyule 2011 g

Pitanie ravnoshipogo Lithodes aequispinus i sinego Paralithodes platypus krabov obitayuschikh na shelfe i materikovom sklone severnoj chasti Okhotskogo morya

Pitanie ravnoshipogo Lithodes aequispinus i sinego Paralithodes platypus krabov obitayuschikh na shelfe i materikovom sklone severnoj chasti Okhotskogo morya

The complete mitochondrial genome of the blue king crab, Paralithodes platypus (Decapoda: Lithodidae)

Paralithodes platypus (blue king crab) has been an economically important species in Alaska, its abundance has decreased substantially since the mid-1980s. A good knowledge of genomics is conducive to the establishments of effective management and conservation strategies of this species. In this study, the complete mitochondrial genome sequence of P. platypus was determined from whole genome Illumina sequencing data. The circular genome is 16,883 bp in length, and harbors 13 protein-coding genes, 22 tRNA genes, two rRNAs genes and one non-coding control region (D-loop). The base composition of the genome is A (36.2%), C (14.9%), G (12.0%) and T (37.0%), demonstrating an obvious bias of high AT content (73.2%). The genome composition and structure of P. platypus present almost identical to other Paralithodes species. Phylogenetic analysis suggests that P. platypus is closely related to its confamilial counterparts with strong bootstrap values than to the other taxon.

Upper thermal tolerance in red and blue king crab: sublethal and lethal effects

Red and blue king crab (Paralithodes camtschaticus and P. platypus) are both important fisheries species in Alaska. Despite the threat of climate change, the upper thermal tolerance of these species has been little studied. In this paper, we determine the lethal and sub-lethal thermal responses of year-0 juvenile red and blue king crab. Crab were exposed to a range of temperatures for 24 h to determine the lethal temperature at which mortality was 50% (LT50). Feeding rations were determined at sub-lethal temperatures for both species. Finally, crab were held for 45 days at sub-lethal temperatures and growth and long-term mortality rates were measured. The LT50s of red and blue king crab were 24.3 and 21.3 °C, respectively. Feeding ration peaked between 12 and 17 °C for red king crab and between 5 and 10 °C for blue king crab. The growth rate of red king crab decreased at temperatures above 12 °C, while blue king crab exhibited very low growth rates at temperatures 12 °C and above. Increased mortality in the 45-day experiment occurred for red king crab at 20 °C and blue king crab at 17 °C. This study suggests that, within their current distribution, the juveniles of both species could withstand warming of several degrees and not be thermally stressed; however, more research into the effect of increased temperature variability and other response variables, such as resting and active respiration, is needed. In addition, increased temperature could affect other life-history stages differently or have indirect effects, such as altered species interactions and food availability.

Ocean acidification leads to altered micromechanical properties of the mineralized cuticle in juvenile red and blue king crabs

Ocean acidification (OA) adversely affects a broad range of marine calcifying organisms. Crustaceans, however, exhibit mixed responses to OA, with growth or survival negatively affected in some species, but unaffected or positively affected in others. In crustaceans, the mineralized cuticle resists mechanical loads, provides protection from the environment, and enables mobility, but little is known about how OA or interactions between OA and temperature affect its structure or function. Here, the effects of OA on the mechanics, structure, and composition of the cuticle in two Alaska king crab species was assessed. Juvenile blue king crabs (Paralithodes platypus) were exposed for a year to three pH levels, 8.1 (ambient), 7.8 and 7.5. Juvenile red king crabs (Paralithodes camtschaticus) were exposed for ~6months to two pH levels, 8.0 and 7.8, at three temperatures: ambient, ambient +2°C, and ambient +4°C. Cuticle microhardness (a measure of resistance to permanent or plastic mechanical deformation), thickness, ultrastructure, and elemental composition were assessed in two body regions, the carapace and the crushing chela (claw). In both species tested, OA reduced endocuticle microhardness in the chela, but not in the carapace. There was no effect of pH or temperature on total procuticle thickness of the chela or carapace in either species. Reductions in microhardness were not driven by reduced calcium content of the shell. In fact, calcium content was significantly elevated in the carapace of blue king crabs and in the chela of red king crabs exposed to lower than ambient pH at ambient temperature, suggesting that calcium content alone is not a sufficient proxy for mechanical properties. Reduced chela microhardness, indicative of more compliant material, could compromise the utility of crushing chelae in feeding and defense.