## 2022 Vol. 41, No. 3

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2022, 41(3)
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2022, 41(3): 1-2.
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2022, 41(3): 1-10. doi: 10.1007/s13131-021-1922-z
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In the western and central Pacific Ocean, upper strata waters exhibit highly dynamic oceanographic features under ENSO variability. This has been proved to be responsible for the dynamic change of both abundance and zonal distribution of skipjack tuna (Katsuwonus pelamis). Although causality has been suggested by researchers using physical–biological interaction models, cumulative evidence needs to be obtained and the tenability of assertion needs to be tested from an ecological habitat perspective, based on fisheries data. For purse seine fishery, the use of catch per unit effort (CPUE) as an indication of the abundance is confusing because of technical improvements over the whole exploitation history and unbalanced individual fishing characteristic of vessels. It is particularly interesting to discriminate between habitat characteristics in comparative scenarios of CPUE application. This study identified habitat traits based on a series of oceanographic factors from a global ocean reanalysis model. A comparison was conducted between two habitat models based on unprocessed purse seine CPUE and standardized CPUE considering fishing characteristics. The results suggest that standardized CPUE could model the regular zonal shift of habitat compatible with the observed fishing efforts transfer, and achieved better prediction capacity than unprocessed CPUE. Furthermore, the habitat of skipjack tuna was also characterized and linked with surface and subsurface thermal environment, ocean current, dissolved oxygen, biotic environment, and ENSO variability. The monthly-averaged habitat suitable index, derived from the optimal habitat model prediction, showed a significant linear relationship with the southern oscillation index, which suggested that El Niño episodes eventually provide more preferable habitat for skipjack tuna under ENSO variability.
2022, 41(3): 11-23. doi: 10.1007/s13131-021-1933-9
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The majority of fishery stocks in the world are data limited, which limits formal stock assessments. Identifying the impacts of input data on stock assessment is critical for improving stock assessment and developing precautionary management strategies. We compare catch advice obtained from applications of various data-limited methods (DLMs) with forecasted catch advice from existing data-rich stock assessment models for the Indian Ocean bigeye tuna (Thunnus obesus). Our goal was to evaluate the consistency of catch advice derived from data-rich methods and data-limited approaches when only a subset of data is available. The Stock Synthesis (SS) results were treated as benchmarks for comparison because they reflect the most comprehensive and best possible scientific information of the stock. This study indicated that although the DLMs examined appeared robust for the Indian Ocean bigeye tuna, the implied catch advice differed between data-limited approaches and the current assessment, due to different data inputs and model assumptions. Most DLMs tended to provide more optimistic catch advice compared with the SS, which was mostly influenced by historical catches, current abundance and depletion estimates, and natural mortality, but was less sensitive to life-history parameters (particularly those related to growth). This study highlights the utility of DLMs and their implications on catch advice for the management of tuna stocks.
2022, 41(3): 24-33. doi: 10.1007/s13131-021-1925-9
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Long-term variations in population structure, growth, mortality, length at median sexual maturity, and exploitation rate of threadfin bream (Nemipterus virgatus) are reported based on bottom trawl survey data collected during 1960–2012 in the Beibu Gulf, South China Sea. Laboratory-based analyses were conducted on 16791 individuals collected quarterly in eight different sampling years. Average body length, estimated asymptotic length, and percentage of large individuals have decreased significantly with the growth of marine catch and fishing power, indicating individual miniaturization of this fish species. Estimated exploitation rates indicate that the N. virgatus stock in the Beibu Gulf was moderately exploited in 1960 and 1962 and overexploited after 1992. This stock was taking a good turn in status in 2012, with the lowest exploitation rate since 1992 and ceased downward trend in length indexes. These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of this commercial fish species. Biological characteristics of most commercial fish species have phenotypic plasticity and might change over years in response to fisheries management. Therefore, attentions should be paid on variations in fish biological characteristics, when evaluating the effectiveness of current measures to control the total catch for all fisheries.
2022, 41(3): 34-43. doi: 10.1007/s13131-021-1902-3
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The size-spectrum model has been considered a useful tool for understanding the structures of marine ecosystems and examining management implications for fisheries. Based on Chinese tuna longline observer data from the central and eastern tropical Pacific Ocean and published data, we developed and calibrated a multispecies size-spectrum model of twenty common and commercially important species in this area. We then use the model to project the status of the species from 2016 to 2050 under five constant-fishing-mortality management scenarios: (1) F=0; (2) F=Frecent, the average fishing mortality from 2013 to 2015; (3) F=0.5Frecent; (4) F=2Frecent and (5) F=3Frecent. Several ecological indicators were used to track the dynamics of the community structure under different levels of fishing, including the mean body weight, slope of community size spectra (Slope), and total biomass. The validation demonstrated that size-at-age data of nine main catch species between our model predictions and those empirical data from assessments by the Western and Central Pacific Fisheries Commission matched well, with the R2>0.9. The direct effect of fishing was the decreasing abundance of large-sized individuals. The mean body weight in the community decreased by ~1 500 g (21%) by 2050 when F doubled from Frecent to 2Frecent. The higher the fishing mortality, the steeper the Slope was. The projection also indicated that fishing impacts reflected by the total biomass did not increase proportionally with the increasing fishing mortality. The biomass of the main target tuna species was still abundant over the projection period under the recent fishing mortality, except Albacore tuna (Thunnus alalunga). For sharks and billfishes, their biomass remained at relatively higher levels only under the F=0 scenario. The results can serve as a scientific reference for alternative management strategies in the tropical Pacific Ocean.
2022, 41(3): 44-52. doi: 10.1007/s13131-021-1900-5
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2022, 41(3): 53-60. doi: 10.1007/s13131-021-1805-3
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Antitumor activity is one characteristic function of some certain antimicrobial peptides (AMPs) found in recent years. In the present study, we attempted to detect potential anticancer activity of a recombinant piscidin 5-like from Larimichthys crocea (rLc-P5L) which owned widely antibacterial and strong antiparasitic activity in vitro. The light microscope observation indicated rLc-P5L was of antitumor activity to HeLa cells, 293T cells and L929 cells. MTT assay showed the toxic sensitivity of rLc-P5L to three tumor cell strains was 293T>L929>HeLa. Scanning electron microscope (SEM) results showed rLc-P5L behaved like a lytic peptide to cause damage on cells membrane of L929 cells by forming globular clusters, even pores at 60 μmol/L, or degrading membrane to make it completely lose cytoskeleton structure at 80 μmol/L; rLc-P5L treatment also resulted in DNA degradation. Fluorescence observation results indicated rLc-P5L could cause L929 cells at least two obvious changes: one is nucleus, nuclear chromatin condensed in the margin, nuclear volume became smaller and shrank to be out of shape, or lysed to be debris; the other is cytoskeleton, they became disordered and polarized to make cells atrophic shapes, or even lysed to be debris. In summary, rLc-P5L owned potential anticancer activity causing membrane structure damage and genome DNA degradation. Interestingly, treatment with different concentration of rLc-P5L seemingly caused the similar but different changes, whether it indeed gave rise to cancer cells diverse death way, the further studies should be performed, and the detailed mechanisms were still need further explored.
2022, 41(3): 61-69. doi: 10.1007/s13131-021-1824-0
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The identity of Rostraria bierii, originally described as a larval amphinomid from Cape Setozaki, Pacific coast of Japan, is investigated. Based on the original description and illustrations, reinterpretations conclude the “larva” to represent a partial juvenile or adult magelonid specimen, broken after the first chaetiger. The original figures are compared with several known magelonid species to justify the new placement. The authors suggest the supposed amphinomid larva is a Magelonidae taxon inquirendum. The identity of the species is discussed in line with the current knowledge of the Magelonidae in the western Pacific and a key to all known species within the region is provided to aid identifications. Current gaps in our taxonomic knowledge of the Magelonidae of the western Pacific are highlighted and discussed.
2022, 41(3): 70-75. doi: 10.1007/s13131-021-1928-6
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It has been widely recognized that biological invasion has become one of the greatest threats to the ecosystem. Codium fragile is an invasive species which exhibits a variety of attributes like parthenogenesis, winter fragment, and vegetative reproduction; and therefore, it has become a successful invader, colonizing most subtropical regions. In China’s southeast coastal aquaculture waters, the green algal bloom caused by C. fragile will probably become a serious problem. In order to understand more details about the species, an experiment focused on its reproductive characteristics was conducted using culture established from a sample collected in the aquaculture raft of the Nan’ao Island in the South China Sea. The results showed that there were two types of gametes resembling aplanospores and zoospores respectively, both of which were able to germinate. During the gametes liberation, a long mucilage tube was formed out of the mouth of the gametangium assisting dispersal of gametes away from the parent plant. This tube was adapted not only to its surrounding flowing water environment but also to its parent plant’s outer gelatinous structure. In general, the optimum temperature for gametes release and germination was 15−20°C and 15°C, respectively, which corresponded to the local offshore marine water. The plant was observed to produce vegetative buds under favourable reproductive conditions which were called propagules. They were capable of developing into filamentous thalli. The results will provide some scientific evidences for revealing the biological mechanism of bloom and control strategies of invasive green algae.
2022, 41(3): 76-85. doi: 10.1007/s13131-021-1807-1
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The diversity, community composition and 16S rRNA gene abundance of bacterioplankton along a transect across an upwelling area off the eastern coast of Hainan Island (the Qiongdong upwelling) were investigated in August of 2016 using high throughput sequencing and quantitative PCR assay of 16S rRNA genes. Compared with the offshore stations, the inner-shelf stations had higher bacterial gene abundance (up to 3 fold) and operational taxonomic unit richness, a result of the influence of upwelled and fresher waters. Overall, a majority of the reads were affiliated with Gammaproteobacteria (11%74%) and Alphaproteobacteria (14%43%). The structure of the bacterial community was significantly affected by salinity, dissolved oxygen, \begin{document}${\rm{NO}}_3^-$\end{document} and \begin{document}${\rm{NH}}_4^+$\end{document}, which also defined the physicochemical features of the upwelled waters. Horizontally, the relative abundances and gene abundances of Rhodobacteraceae, SAR86, Cyanobacteria and Bacteroidetes in eutrophic zone decreased from the inner to outer shelves and slope, whereas Alteromonas, Vibrio and Oceanospirillaceae exhibited an opposite trend. This study stresses the riverine influence on the oceanographic condition and spatial variability of bacterioplankton diversity and distribution in the Qiongdong upwelling.
2022, 41(3): 86-93. doi: 10.1007/s13131-021-1926-8
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Marine microorganisms were considered to be important sources of marine bioactive compounds. The major objective of the study was to isolate and characterize bacteria with antimicrobial activities from the various marine environment of Egypt. In this respect, thirty-five bacterial isolates were recovered from sediment samples collected from different spots along the Egyptian Red Sea coastline and Alexandria coastline during the summer season of 2017 and 2018. According to the morphological, physiological, and biochemical characteristics, the bacterial isolates were clustered into 13 groups designated as A, B, ···, M. And, 14 Gram-negative and 21 Gram-positive bacteria were determined. The isolated bacterial strains were screened for their potentiality for antimicrobial agent(s) production against ten indicator strains. Strain Mo13 was showed high antimicrobial activity against all empirical strains. Subsequently, the most promising marine bacterial isolate with code MO13 was identified as Bacillus zhangzhouensis OMER4 according to the phenotypic characterization through morphological, physiological, and biochemical tests as well as genotypic characterization through the 16S rDNA technique. The bioactive components were extracted with ethyl acetate, then analyzed using GC-MS and the substantial component was recognized as phenol, 2, 4-bis(1, 1-dimethyl ethyl).
2022, 41(3): 94-102. doi: 10.1007/s13131-021-1932-x
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Fixed-station sampling design was widely used in fishery-independent surveys because of its characteristics of convenient sampling station setting, but the non-probabilistic (fixed) nature made it more uncertainty of drawing inferences on population. The performance of fixed-station sampling design for multispecies survey has not been evaluated, and we are uncertain if the design could detect the temporal trends of different populations in multispecies fishery-independent survey. In this study, spatial distribution of abundance indices for three species with different spatial distribution patterns including small yellow croaker (Larimichthys polyactis), whitespotted conger (Conger myriaster) and Fang’s blenny (Enedrias fangi) were simulated using ordinary kriging interpolation as the “true” population distribution. The performance of fixed-station sampling design was compared with simple random sampling design by resampling the simulated “true” populations in this simulation study. The results showed that the fixed-station sampling design had the power to detect the seasonal trends of species abundance. The effectiveness of fixed-station sampling design were different in different species distribution patterns. When the species had even distribution, fixed-station sampling design could get high quality abundance data; when the distribution was uneven with heterogeneity or patchiness, fixed-station sampling design tended to underestimate or overestimate the abundance. Evidently, the estimates of abundance index based on the fixed-station sampling design must be calibrated cautiously while applying them for fisheries stock assessment and management. This study suggested that fixed-station sampling design could catch the temporal dynamics of population abundance, but the abundance estimates from the fixed-station sampling design could not be treated as the absolute estimates of populations.
2022, 41(3): 103-108. doi: 10.1007/s13131-021-1921-0
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A new spectrophotometric method based on a liquid waveguide capillary cell for an enhanced detection was developed to measure nanomolar iodate concentrations. This method has a detection limit and precision of 1–2 nmol/L, which is equivalent to 10% that of conventional methods, a recovery of 97.7%–104.0%, and a working range of 10–120 nmol/L. Water samples were collected from three estuaries and one coastal ocean for testing, and the proposed technique detected as low as 11 nmol/L and 18 nmol/L iodate in these samples. This newly developed method is helpful in understanding the biogeochemical cycle of iodine in nature.
2022, 41(3): 109-113. doi: 10.1007/s13131-021-1893-0
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