[Dominant species of cephalopods and their niche characteristics in offshore of northern South China Sea]. / å—æµ·åŒ—éƒ¨è¿‘æµ·å¤´è¶³ç±»ä¼˜åŠ¿ç§åŠå ¶ç”Ÿæ€ä½ç‰¹å¾.

To understand the relationships among dominant species of cephalopods in offshore nor-thern South China Sea, we examined the niche characteristics of these dominant species from both spatial and temporal dimensions using the index of relative importance (IRI), the niche breadth and overlap indices based on fishery resources data from the bottom-trawl survey for four seasons during 2014-2015. The results showed that five dominant species of cephalopods were recorded for four seasons, including Loligo edulis, L. chinensis, L. beka, Sepia esculenta, and L. duvaucelii. The first two species were shared by all seasons. Compared with historical data, the composition of dominant cephalopods species had changed. The cephalopods resource exhibited obvious temporal and spatial variations. Stock density was higher in the sea area extending from the southern Hainan Island to eastern Guangdong Province than that in Beibu Gulf. The seasonal variation was characte-rized by the largest in summer but the smallest in winter. The temporal and spatial niche analysis showed that there was inconsistent in the order between temporal and spatial niche breadths for domi-nant species. L. edulis (1.32) and L. chinensis (3.90) occupied the largest temporal and spatial niche breadths, respectively. The smallest of temporal and spatial niche breadths were shown for S. esculenta (0.98) and L. duvaucelii (2.04), respectively. Though the temporal niche overlap was numerically larger than the spatial niche overlap, both of them had higher values in interspecies among L. edulis, L. chinensis, L. beka, and the lower overlap for the species pairs between L. duvaucelii and other species. The result of correlation analysis suggested that niche breadth exhibited a significant negative correlation with variation in abundance on both temporal and spatial scales. The ecological niche could reflect the tempo-spatial changes of species resource, which enriched the traditional methods of fishery communities.

[Trophic niche of medium-form and dwarf-form of purple flying squid Sthenoeuthis oualaniensis in the central and western South China Sea]. / å—æµ·ä¸­è¥¿éƒ¨æµ·åŸŸé¸¢ä¹Œè´¼ä¸­åž‹ç¾¤å’Œå¾®åž‹ç¾¤çš„è¥å »ç”Ÿæ€ä½.

To explore the characteristics of carbon and nitrogen stable isotope and trophic niche between two forms (medium-form and dwarf-form) of the purple flying squid Sthenoteuthis ouala-niensis, we collected samples from the central and western South China Sea in August 2017 to analyze the values of carbon and nitrogen stable isotope and the changes of trophic level for different mantle lengths. We further compared the trophic niche differences of the two forms populations. The results showed that for the medium-form, the δ13C value ranged from -19.54‰ to -18.10‰ and the δ15N value ranged from 7.79‰ to 9.45‰. The average trophic level of medium-form was 2.90 and ranged from 2.72 to 3.21. For the dwarf-form, the δ13C value ranged from -19.69‰ to -18.43‰, and the δ15N value ranged from 8.02‰ to 8.99‰. The average trophic level of the dwarf-form was 2.91 and ranged from 2.79 to 3.08. There were significant differences of δ15N but no differences of δ13C values between the medium-form and dwarf-form of purple flying squid. The mantle length had a significant impact on δ13C and δ15N, with the value of δ15N increasing with the mantle length. The trophic niche breadth and the trophic level of the medium-form purple flying squid were more diverse than those of dwarf-form.

[Probability distribution characteristics of stock density in offshore of northern South China Sea.] / 南海北部近海渔业资源密度概率分布特征.

Based on catch data from the bottom trawl survey by eight cruises in offshore of northern South China Sea during 2014-2017, we analyzed the stock density distribution and explored its probability distribution with statistical method, which was further used to estimate the mean stock density in this region. The results showed that the coefficient of variation (CV) for stock density ranged from 0.67 to 1.03 for all the periods, indicating a highly uneven spatial distribution of stock density. The frequency distribution of fishery resource density was characterized by obvious right-skewed, which was dominated by stock density of 0-1000 kg·km-2. The results of one sample Kolmogorov-Smirnov test indicated that three probability distribution patterns were suitable for stock density in this region, including Lognormal, Gamma and Weibull distributions. In terms of the mean stock density estimation, the values from Lognormal showed no statistically significant difference from those from others, but the opposite result was obtained between Gamma and Weibull distributions. Compared with 1960s-1970s, the appropriate probability distribution pattern of stock density has changed from single to multiple types. Variation of the proportion of low catch resulted from the changes in the structure of fishery resources, fishing effort and climate change might cause the alte-ration of probability distribution.

A retrospective case series illustrating a possible association between a widened hilum and sialolith formation in the submandibular gland.

OBJECTIVE: The purpose of this study was to explore any association between anatomical variances in the ductal system and sialolith formation using sialoendoscopy and acrylic resin replication of the ductal system. METHODS: A retrospective study of 372 submandibular gland sialoendoscopies was performed to review the findings of the submandibular gland duct anatomy. Using sialoendoscopy and replicated casts, a high rate of hilar widening was noted in patients with submandibular sialolithiasis. RESULTS: Sialolithiasis was detected in 326 of the patients who presented with obstructive symptoms. Around 67% (285/426) of the stones were located in the distal third of the ducts or at the hilum of the submandibular gland. During the sialoendoscopic procedure, the anatomy of the ductal system was examined and 285/326 (87.4%) of the hilums were noted to be widened like a basin. The anatomy of the duct from the replicated casts demonstrated a treelike structure and the basin-like widening of the hilum was found in all the excised submandibular glands. CONCLUSION: Using sialoendoscopy, a high number of patients presenting with sialolithiasis in the submandibular gland seem to have an anatomical variance in the hilar region. The reproduced ductal system from excised glands also demonstrated this abnormal widening of the hilum. Although further studies need to be performed, we try and explain why there is such a high prevalence of hilar widening in patients with submandibular sialolithiasis.

[Risk assessment of coastal ecosystem in Beibu Gulf, Guangxi of South China].

Based on the marine ecological investigation in the coastal area of Beibu Gulf, Guangxi in September 2009, a GIS-based evaluation was conducted on the present status of ecological environment quality, including seawater quality, nutrient level, biomass, primary productivity, biodiversity, and ecological buffer capacity, in the area in autumn, and the integrated ecological risk index (ERI) was adopted to assess the risk of the coastal ecosystem in the Gulf. In September 2009, the study area had a better ecological environment quality. Most of the risk indicators were at medium or lower level, and the total area was overall at low ecological risk level. The ERI showed that there was an obvious spatial heterogeneity in the distribution of the ecological risk. The nearer to the harbors, the higher the risk was.

[Evaluation of sustainable utilization of fishery resources in Guangdong Province].

Sustainable utilization of fishery resources is the key for the sustainable development of fisheries, and its evaluation is a critical topic in the management of fisheries. Based on the theories of sustainable utilization, an index system suitable for the evaluation of the sustainable utilization of fishery resources in Guangdong Province was established, and a hierarchy and comprehensive grey evaluation model was adopted to evaluate this sustainable utilization in 1978-2007. In the study period, the utilization level of fishery resources in this province had an overall decrease, being the lowest in 1998, only 37.3% of that in 1978; but in the nearest 10 years, this utilization level had an increasing trend, with that in 2007 being 55.1% of 1978. The results of comprehensive evaluation were consistent with the observed facts, indicating that the model was feasible to evaluate the sustainable utilization of regional fishery resources.

[Faunal characteristics and distribution pattern of crustaceans in the vicinity of Pearl River estuary].

Based on the data of bottom trawl surveys in the vicinity of Pearl River estuary in August (summer), October (autumn), December (winter) 2006, and April (spring) 2007, the faunal characteristics and distribution pattern of crustaceans were analyzed. A total of 54 species belonging to 25 genera, 17 families, and 2 orders were collected, including 22 species of shrimps, 22 species of crabs, and 10 species of squills. Most of the crustaceans were tropical-subtropical warm-water species, a few of them were eurythermal species, and no warm-water and cold-water species occurred. Euryhaline species were most abundant, followed by halophile species, and the low-salinity species were the least. Most of the crustacean species belonged to the fauna of Indian Ocean-western Pacific Ocean. The faunal assemblages were closer to those of the East China Sea, Philippine Sea, Indonesia Sea, and the Japan Sea, and estranger with those of the Yellow Sea, Bohai Sea, and Korea Sea. The dominant species were Metapenaeus joyner, Oratosquilla oratoria, Charybdis miles, Portunus sanguinolentus, Harpiosquilla harpax, Charybdis feriatus, Charybdis japonica, Oratosquilla nepa, Solenocera crassicornis, Portunus trituberculatus, and Calappa philargius. The crustaceans had the largest species number (33) in autumn and the least one (26) in spring, and the highest stock density at the water depth of < 40 m, especially at 10-20 m. The average stock density of the crustaceans was estimated to be 99.60 kg x km(-2), with the highest (198.93 kg x km(-2)) in summer and the lowest (42.35 kg x km(-2)) in spring. Of the 3 species groups, crabs had the highest stock density (41.81 kg x km(-2)), followed by shrimps (38.91 kg x km(-2)), and squills (18.88 kg x km(-2)). The stock densities of the 3 species groups showed an obvious seasonal variation. Shrimps had the highest stock density (120.32 kg x km(-2)) in summer and the lowest density (0.67 kg x km(-2)) in spring, while crabs and squills had the highest density (62.01 and 29.49 kg x km(-2), respectively) in winter and the lowest density (24.64 and 6.30 kg x km(-2), respectively) in autumn.

[Effects of fishing on the marine ecosystem of Beibu Gulf].

By using Ecopath with Ecosim 5.1 software, the Ecosim model of Beibu Gulf marine ecosystem in 1959-1960 was constructed, which included about 20 functional groups such as fishery, marine mammals, sea-birds, sharks, pelagic fishes, demersal fishes, and benthic crustaceans, etc. Through the comparison with the investigation data in 1997-1999, the effects of fishing on the structure and function of Beibu Gulf marine ecosystem were analyzed. The results indicated that with the increasing fishing pressure in past forty years, the ecosystem structure and function shifted drastically, with the biomass of long-lived, high trophic level and piscivorous fishes declined while short-lived and small fishes and benthic invertebrates dominated gradually. The biomass of piscivorous species in 1999 was only 6% of that in 1960, while cephalopods increased 2.7 times or more. The trophic level of the catch declined from 3.2 in 1960 to 2.98 in 1999, which fitted the rule of "fishing down the food web" and suggested that the present exploitation patterns were unsustainable. Based on the data of the 1990s, the changes of the ecosystem under decreasing fishing pressure were predicted. This study validated the feasibility of Ecosim model in predicting the effects of fishing pressure on marine ecosystem.