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1.
The hard tissues of squid can provide important information for species identification. In this study, we used statolith and beak to identify three squid species including Uroteuthis duvaucelii, Loliolus beka, and U. edulis in the South China Sea. Because of the highly overlapping habitat and similar body morphology of the three squid species, we explored four different ways to identify them, by using statolith, upper beak, lower beak and a combination of statolith and beak. An outline geometric morphometric method and stepwise discriminant analysis were used to evaluate the most suitable method for the identification. We found that the combination of statolith and beak had the highest cross validation rate that was 75.0%, 87.5% and 88.7% for U. duvaucelii, L. beka and U. edulis, respectively. Using two beaks had similar results and the lowest cross validation rate was 60.0%, 50.0%, and 73.7% for the upper beak, 46.9%, 58.5% and 75.3% for the lower beak of U. duvaucelii, L. beka and U. edulis, respectively. Analyzing with the statolith had moderate cross validation which was 72.2%, 80.0%, and 87.7% for U. duvaucelii, L. beka and U. edulis, respectively. From the results it is suggested when the entire body of a squid is available, a combination of statolith and beak should be used for the identification. When only one hard tissue is available, species identification can be subjected to large errors.  相似文献   

2.
The neon flying squid (Ommastrephes bartramii) is a short-lived opportunistic species widely distributed in subtropical and temperate waters in the North Pacific Ocean. The life cycle of O. bartramii from planktonic eggs to nektonic adults is closely linked to oceanographic conditions. The fluctuations in O. bartramii abundance and distribution tend to increase and widen continuously due to the heavy influences of ocean-climate events on various spatio-temporal scales. In this study, we reviewed the interaction between O. bartramii and oceanography variability in the North Pacific with respect to large-scale climatic-oceanic phenomena including El Niño, La Niña, Kuroshio, Oyashio and Pacific Decadal Oscillation (PDO), as well as regional environmental variables such as sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS), chlorophyll-a (Chl-a) concentration, and plankton density. The population dynamics of O. bartramii is mediated mainly by meso- and large-scale climatic-oceanic events (e.g., Kuroshio and Oyashio Currents) rather than other local environmental conditions (e.g., SST and Chl-a concentration), because all of the oceanographic influences are imposed on the context of large-scale climate changes (e.g., PDO). An unstructured-grid finite-volume coastal ocean model coupled with an individual-based model is proposed to simulate relevant physical-biological oceanographic processes for identifying ocean-climate influence and predicting O. bartramii distribution and abundance in the North Pacific. Future research needs to be focused on improving the knowledge about early life history of O. bartramii and evaluating the relationship between marine physical environment and two separate passive drifting life stages of O. bartramii including free-floating eggs and planktonic paralarvae.  相似文献   

3.
Beak of cephalopod is an important hard tissue.Understanding the morphology of beak can yield critical information on the role of cephalopods in the ecosystem.The south patagonic stock of the Argentine shortfin squid,Illex argentinus,is not only one of the most important fishing targets,but also one of the most important species in the marine eco-system of the southwest Atlantic.A total of 430 samples of I.argentinus,including 229 females 103-346mm in mantle length(ML) and 201 males 140-298mm in ML,were collected from the area off the Exclusive Economic Zone of Argentinean waters by Chinese squid jigging vessels during February to May 2007.The morphology of their beaks was evaluated.The relationships between beak morphological variables and ML differed significantly among males and females.They could be best described by logarithmic functions for females and linear functions for males except for upper wing length(UWL) and lower rostrum length(LRL),which followed exponential functions in their relationships with ML.The results showed the sexual dimorphism in the relationship between ML and beak morphology for the south patagonic stock of I.argentinus.However,no significant difference was found between males and females in the relationships of beak morphological variables(except for UWL) versus body weight(BW),suggesting that the relationship between beak morphological variables and BW can be used for estimating the biomass consumed by their predators.  相似文献   

4.
Little information is available on biogenic elements (carbon, nitrogen, phosphorus and sulfur) and the ecological stoichiometric characteristics of plants in coastal wetlands. To investigate the contents of carbon, nitrogen, phosphorus and sulfur of plants, and their ecological stoichiometric characteristics in the Yellow (Huanghe) River Delta, plant samples were collected from two typical salt marshes (Suaeda salsa and Phragmites australis wetlands) during the period of from August to October in 2007, and the ratios of C/N, C/P, N/P, C/N/P and C/N/P/S were calculated. Results showed that during the studying period, plant C, N and P were lower than the global average values, and plant N and P were lower than the China’s average values. Leaf C and S in Suaeda salsa were significantly lower than those in Phragmites australis (P < 0.05), and leaf N and P in Suaeda salsa and Phragmites australis showed no significant differences (P > 0.05). Average C/N ratios were 23.75 in leaf, 73.36 in stem, 65.67 in root of Suaeda salsa, and 33.77 in leaf, 121.68 in stem, 97.13 in root of Phragmites australis. Average C/N ratios of Suaeda salsa and Phragmites australis were all great than 25, indicating the salt marsh in the Yellow River Delta is an N limitation system. Average C/P ratios were 276.78 in leaf, 709.28 in stem and 1031.32 in root of Suaeda salsa, and 536.94 in leaf, 768.13 in stem and 875.22 in root of Phragmites australis. The average N/P ratios of Suaeda salsa were 12.92 in leaf, 10.77 in stem and 10.91 in root, and the average N/P ratios of Phragmites australis were 16.40 in leaf, 7.40 in stem and 6.92 in root, indicating the Suaeda salsa wetlands were N limited and Phragmites australis wetlands were N limited in August and P limited in October in 2007. The average C/N, C/P and C/N/P ratios in Suaeda salsa and Pragmites australis were higher than the global average values, indicating the lower quality of organic matter provided by wetland plants in the Yellow River delta.  相似文献   

5.
Change in environmental conditions with altitudinal gradients induces morpho-anatomical variations in plants that have been poorly documented in intertropical regions. Five species with three life forms, cryptophyte (Alchemilla procumbens, Geranium seemannii), hemicryptophyte (Acaena elongata, Lupinus montanus), and phanerophyte (Symphoricarpos microphyllus), distributed along an altitudinal gradient in the Sierra Nevada of central Mexico, were studied. The aims were to identify and evaluate their morpho-anatomical modifications under the hypothesis that the sizes of individuals and of their wood and leaf cell types decrease as elevation increases. Three individuals per species per site were collected at seven locations along the altitudinal gradient (2949-3952 m). Their morpho-anatomical characters were analyzed through multiple regression analyses. Elevation was the variable that best explained anatomical changes in the leaf and wood of the five species. Canopy density and potassium content in the soil also contributed to explain the variation in anatomical variables along the gradient. As elevation increased a bimodal pattern was observed in various anatomical characters as in the leaf width of A. elongata, A. procumbens and G. seemannii and in the vessel diameter of A. procumbens, G. seemannii, and L. montanus. Other features as the vessel diameter of A. elongata, the fiber length of S. microphyllus, and the ray width of A. elongata increased as the elevation increased. Anatomical traits have a tendency to decrease in size but just toward the end of the gradient, which is probably related to changes in canopy density. The plant response to the altitudinal gradient is more focused on anatomical adaptations than morphological variation; it is also species dependent.  相似文献   

6.
Accordion-shaped traps are widely used in China to catch the Asian paddle crab Charybdis japonica but traps of conventional design often catch juvenile crabs. A new type of accordion-shaped trap with an escape vent (L×W=4.3 cm×3.0 cm) was designed and a comparative study between the newly designed and conventional traps was performed in the artificial reef area of Zhuwang, Laizhou Bay, China from June to August 2012. The mean catch per unit effort (CPUE) of undersized crabs was significantly lower in the vented traps than in the conventional traps (paired t -test, n=30, P<0.001), while the CPUE of marketable crabs was significantly higher in the vented traps (paired t-test, n=30, P<0.001). The mean size of crabs (carapace length) caught in the vented traps was significantly larger than in conventional traps (paired t-test, n=29, P<0.001). The ratio of undersized crabs was 35.05±2.57% in conventional traps and 12.53±0.69% in vented traps (significantly lower, paired t-test, n=29, P<0.001). Therefore, a 4.3 cm×3.0 cm escape vent was considered appropriate for C. japonica fishing in the artificial reef area. This finding will assist the development of more sustainable and efficient crab fishing methods using accordion-shaped traps.  相似文献   

7.
The shell color of Pacific oyster (Crassostrea gigas) is a desirable trait; but the nutritional studies on C. gigas with different shell colors have not been conducted. Through successive selective breeding, five shell color strains of black (B), purple (P), orange (O), golden (G) and white (W) C. gigas have been developed. The aim of this study was to evaluate the chemical composition and nutritional value of five shell color strains and one commercial population with a common color. The biochemical composition including moisture, total protein, glycogen, ash, total fat, fatty acids (FA), amino acids and minerals was detected. The results indicated that the protein (50.76%–56.57%) was the major component. The content of glycogen showed a significant difference between orange shell and golden shell strains, as well as between commercial population and golden shell strain. In addition, all shell color strains contained a large amount of essential amino acids (12.20–14.15 g (100 g)?1), of them leucine (2.81–3.29 g (100 g)?1) and lysine (2.79–3.28 g (100 g)?1) were predominant. The oysters were rich in polyunsaturated fatty acids (42.26%–45.24% of total fatty acid) with high levels of DHA (18.53%–21.16% of total fatty acid) and EPA (17.23%–18.68% of total fatty acid). Significant differences of mineral contents (Mg, Zn, Fe and Cu) were identified among the six populations. These results indicated that C. gigas with different shell colors presented rich nutritional value with high protein, glycogen, essential amino acids and polyunsaturated fatty acids. The biochemical composition obtained in this study is useful for selective breeding of C. gigas with different shell colors.  相似文献   

8.
The effects of different phosphorus (P) concentrations (0.36, 3.6, and 36 μmol/L corresponding to low-, middle-, and high-P concentration groups, respectively) and nitrogen (N)/P ratios on the growth and photosynthetic characteristics of Skeletonema costatum and Prorocentrum donghaiense were studied. For both species, the high-P (HP) concentration group showed the greatest algal density and highest specific growth rate. Changes in the maximum efficiency of photosystem II (F v /F m ) were monitored under the various P and N/P conditions. The largest decrease in F v /F m was in the low-P (LP) group in S. costatum and in the HP group in P. donghaiense. There were high rapid light curves and photochemical quantum yields (Φ PSII) for S. costatum in the HP group, while the actual photosynthetic capacity was higher in P. donghaiense than in S. costatum in the MP group. Under eutrophic but relatively P-restricted conditions, P. donghaiense had higher photosynthetic activity and potential, which could cause this dinoflagellate to increasingly dominate the phytoplankton community in these conditions. Under the same P concentration and N/P ratio, P. donghaiense had a larger relative maximum rate of electron transport and higher Φ PS II values than those of S. costatum. These differences between P. donghaiense and S. costatum may explain the interaction and succession patterns of these two species in the Changjiang (Yangtze) River estuary from a photosynthesis perspective.  相似文献   

9.
To understand the effects of leaf physiological and morphological characteristics on δ 13C of alpine trees, we examined leaf δ 13C value, LA, SD, LNC, LPC, LKC, Chla+b, LDMC, LMA and Narea in one-year-old needles of Picea schrenkiana var. tianschanica at ten points along an altitudinal gradient from 1420 m to 2300 m a.s.l. on the northern slopes of the Tianshan Mountains in northwest China. Our results indicated that all the leaf traits differed significantly among sampling sites along the altitudinal gradient (P<0.001). LA, SD, LPC, LKC increased linearly with increasing elevation, whereas leaf δ 13C, LNC, Chla+b, LDMC, LMA and Narea varied non-linearly with changes in altitude. Stepwise multiple regression analyses showed that four controlled physiological and morphological characteristics influenced the variation of δ 13C. Among these four controlled factors, LKC was the most profound physiological factor that affected δ 13C values, LA was the secondary morphological factor, SD was the third morphological factor, LNC was the last physiological factor. This suggested that leaf δ 13C was directly controlled by physiological and morphological adjustments with changing environmental conditions due to the elevation.  相似文献   

10.
In present study, the inbreeding depression (ID) of growth and survival of Manila clam (Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families (A 2, B 2, C 2, D 2, E 2, F 2, G 2, H 2 and I 2) were established by mating within nine full-sib families with expected inbreeding coefficient of 0.25. Inbred families showed significant differences in shell length and hatching rate of D-larvae (straight-hinged larvae). The larvae of the nine inbred families grew slower than those of control group (CG), and their ID value ranged from 0.81% ± 6.09% to 16.10% ± 1.49%. The ID value of larval survival rate varied between 27.47% ± 9.36% and 70.50% ± 13.66%. The ID was also detected for juvenile growth in A 2, B 2, C 2, and D 2, which ranged from 4.60 ± 2.21 to 17.71 ± 7.73. The A 2 family maintained the highest juvenile survival rate, whereas the other inbred families exhibited ID values varying between 62.79% ± 4.54% and 96.14% ± 0.87%. The linear relationship of estimated ID between growth and survival was negatively correlated (R = ?0.434, P < 0.05). The results of this study suggested that the ID of growth was common at the larval stage but was less prevalent at juvenile stage. In contrast, the ID of survival increased from larval to juvenile stage. A better understanding of the effect of inbreeding may aid to selective breeding of Manila clam.  相似文献   

11.
There is an increasing requirement for traceability of aquaculture products, both for consumer protection and for food safety. There are high error rates in the conventional traceability systems depending on physical labels. Genetic traceability technique depending on DNA-based tracking system can overcome this problem. Genealogy information is essential for genetic traceability, and microsatellite DNA marker is a good choice for pedigree analysis. As increasing genotyping throughput of microsatellites, microsatellite multiplex PCR has become a fast and cost-effective technique. As a commercially important cultured aquatic species, Pacific oyster Crassostrea gigas has the highest global production. The objective of this study was to develop microsatellite multiplex PCR panels with dye-labeled universal primer for pedigree analysis in C. gigas, and these multiplex PCRs were validated using 12 full-sib families with known pedigrees. Here we developed six informative multiplex PCRs using 18 genomic microsatellites in C. gigas. Each multiplex panel contained a single universal primer M13(?21) used as a tail on each locus-specific forward primer and a single universal primer M13(?21) labeled with fluorophores. The polymorphisms of the markers were moderate, with an average of 10.3 alleles per locus and average polymorphic information content of 0.740. The observed heterozygosity per locus ranged from 0.492 to 0.822. Cervus simulations revealed that the six panels would still be of great value when massive families were analysed. Pedigree analysis of real offspring demonstrated that 100% of the offspring were unambiguously allocated to their parents when two multiplex PCRs were used. The six sets of multiplex PCRs can be an important tool for tracing cultured individuals, population genetic analysis, and selective breeding program in C. gigas.  相似文献   

12.
The age, growth and maturation of Sthenoteuthis oualaniensis were determined with statolith data collected with a light purse seine from the Bashi Channel of central Pacific Ocean. The estimated longevity of the squid was no more than 6 months for females, and no more than 5 months for males. Growth in mantle length (ML) was best described by logistic models for both females and males, while growth in body weight (BW) was best fitted by power curves. The maximum absolute growth rate (AGR) and instantaneous growth rate (IGR) in ML or BW both occurred at 91–105 days for females and 76–90 days for males. Back calculated hatching dates were from October to January, with a peak in December, although the short duration of sampling date might have had an influence on the result. The lower percentage of mature females (37.2%) suggested that the study area during the sampling date was not a spawning ground for the species. Size and age at first maturity were 183 mm ML and 136 days for females, whereas they were 156 mm ML and 85 days for males.  相似文献   

13.
Arc-soft-toe bracket (ASTB), as a joint structure in the marine structure, is the hot spot with significant stress concentration, therefore, fatigue behavior of ASTBs is an important point of concern in their design. Since macroscopic geometric factors obviously influence the stress flaws in joints, the shapes and sizes of ASTBs should represent the stress distribution around cracks in the hot spots. In this paper, we introduce a geometric magnification factor for reflecting the macroscopic geometric effects of ASTB crack features and construct a 3D finite element model to simulate the distribution of stress intensity factor (SIF) at the crack endings. Sensitivity analyses with respect to the geometric ratio H t /L b , R/L b , L t /L b are performed, and the relations between the geometric factor and these parameters are presented. A set of parametric equations with respect to the geometric magnification factor is obtained using a curve fitting technique. A nonlinear relationship exists between the SIF and the ratio of ASTB arm to toe length. When the ratio of ASTB arm to toe length reaches a marginal value, the SIF of crack at the ASTB toe is not influenced by ASTB geometric parameters. In addition, the arc shape of the ASTB slope edge can transform the stress flowing path, which significantly affects the SIF at the ASTB toe. A proper method to reduce stress concentration is setting a slope edge arc size equal to the ASTB arm length.  相似文献   

14.
We examined spatially clustered distribution of jumbo flying squid (Dosidicus gigas) in the offshore waters of Peru bounded by 78°–86°W and 8°–20°S under 0.5°×0.5° fishing grid. The study is based on the catch-per-unit-effort (CPUE) and fishing effort from Chinese mainland squid jigging fleet in 2003–2004 and 2006–2013. The data for all years as well as the eight years (excluding El Niño events) were studied to examine the effect of climate variation on the spatial distribution of D. gigas. Five spatial clusters reflecting the spatial distribution were computed using K-means and Getis-Ord Gi* for a detailed comparative study. Our results showed that clusters identified by the two methods were quite different in terms of their spatial patterns, and K-means was not as accurate as Getis-Ord Gi*, as inferred from the agreement degree and receiver operating characteristic. There were more areas of hot and cold spots in years without the impact of El Niño, suggesting that such large-scale climate variations could reduce the clustering level of D. gigas. The catches also showed that warm El Niño conditions and high water temperature were less favorable for D. gigas offshore Peru. The results suggested that the use of K-means is preferable if the aim is to discover the spatial distribution of each sub-region (cluster) of the study area, while Getis-Ord Gi* is preferable if the aim is to identify statistically significant hot spots that may indicate the central fishing ground.  相似文献   

15.
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16.
Dinoflagellates in the genus Symbiodinium, including nine clades (A–I), mainly form mutualistic symbioses with corals. More than 100 Symbiodinium molecular types have been identified by the ITS2-based genotype method within any given clade, and specifically within Symbiodinium clade C. However, the genotype identification method using the ITS2 sequence is likely to lead to high diversity estimates due to the intra-genomic variations in the ITS2 space; thus, further validation is essential for a correct identification. In this study, the molecular diversity of Symbiodinium ITS2 sequences cloned from two stone corals, Acropora sp. SY-01 and Pocillopora sp. SY-05, and one soft coral, Sarcophyton sp. SY-07, living in the northern part of South China Sea (SCS), were analyzed and compared using the ITS2-based genotype identification method, coupled with ITS2-based secondary structural and phylogenetic analyses. As the result, 12 Symbiodinium ITS2 genotypes were identified, while only six and three Symbiodinium ITS2 genotypes were supported by ITS2-based secondary structural and phylogenetic analyses, respectively. In addition, no shared Symbiodinium ITS2 genotypes were observed among the three coral species, suggesting coral species-dependent Symbiodinium genotypes were within clade C. In summary, the present study provides a theoretical basis for validating the molecular diversity of Symbiodinium ITS2 genotypes in corals.  相似文献   

17.
Rapid, high-throughput and reliable methods are urgently required to accurately detect and monitor harmful algae, which are responsible for algal blooms, such as red and green tides. In this study, we successfully developed a multiplex PCR-based DNA microarray method capable of detecting nine harmful algal species simultaneously, namely Alexandrium tamarense, Gyrodinium instriatum, Heterosigma akashiwo, Karenia mikimotoi, Prorocentrum donghaiense, Prorocentrum minimum, Ulva compressa, Ulva ohnoi and Ulva prolifera. This method achieved a limit of detection (LOD) of 0.5 ng of genomic DNA (orders of magnitude of the deci-nanogram range) in the tested algae cultures. Altogether, 230 field samples from ship ballast waters and seaport waters were used to evaluate the DNA microarray. The clinical sensitivity and specificity of the DNA microarray assay in detecting field samples were 96.4% and 90.9%, respectively, relative to conventional morphological methods. This indicated that this high-throughput, automatic, and specific method is well suited for the detection of algae in water samples.  相似文献   

18.
One new marine oligotrich ciliate, Omegastrombidium hongkongense n. sp., was isolated from a bloom of Noctiluca scuntillans near Port Shelter, Hong Kong. The morphology and infraciliature of this new species were studied on both living and protargol-stained specimens. Its phylogenetic position was discussed based on the sequence of the small subunit rRNA gene. O. hongkongense is different from its congeners with special characters. The cells are usually heart-shaped, and the cell size usually is (20–35) × (20–30) μm in vivo. Its deep buccal cavity extends obliquely to about 1/2 of cell length. It shows prominent apical protrusion. The adoral zone of membranelles is divided into 17–19 collar membranelles and four buccal membranelles. It has one ball-like macronucleus. The girdle kinety forms a closed loop which obliquely surrounds the body. The ventral kinety and thigmotactic membranelles are not observed. The SSU rRNA sequence of O. hongkongense was close to those of Strombidium paracalkinsi and Varistrombidium kelum with approximately 99% similarity. In the phylogenetic trees, O. hongkongense can be grouped with O. elegans and V. kielum species with very low support (16% ML).  相似文献   

19.
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20.
The information of trophic relationship is important for studying the Southern Ocean ecosystems. In this study, three dominant krill species, Euphausia superba, Thysanoessa macrura and Euphausia crystallorophias, were collected from Prydz Bay, Antarctica, during austral summer of 2009/2010. The composition of fatty acids in these species was studied. E. superba and T. macrura showed a similar fatty acid composition which was dominated by C14:0, C16:0, EPA (eicosapentenoic acid) and DHA (decosahexenoic acid) while E. crystallorophias showed higher contents of C18:1(n-9), C18:1(n-7), DHA and EPA than the former two. Higher fatty acid ratios of C18:1(n-9)/18:1(n-7), PUFA (polyunsaturated fatty acid)/SFA (saturated fatty acid), and 18PUFA/16PUFA indicated that E. crystallorophias should be classified as a typical omnivore with a higher trophic position compared with E. superba and T. macrura.  相似文献   

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