| 其他摘要 | Xiaoqing River Estuary and its adjacent waters was once the main spawning ground in Laizhou Bay. In recent decades, due to global climate change, pollution and overfishing, the regional marine ecosystem, including the structure of biological resources and the sustainable utilization of fishery resources, had been seriously impacted. With the aim of understanding the composition and changes of fishery resources as well as the three common economic species’ genetic resources in this region, three voyages in June, August and October 2020 in Xiaoqing River Estuary and its adjacent waters were carried out. Comnbined with analysis of the historical data from 2009 to 2016, we investigated the interannual variation of fishery resources. And three common economic species, Oratosquilla oratoria, Portunus trituberculatus and Penaeus chinensis, were selected to analyze their genetic diversity based on mitochondrial COI gene. The main results were as follows:
1. Seasonal variation of fishery resources in Xiaoqing River Estuary and its adjacent waters in 2020
In 2020, 102 species of fishery resources were captured, with 35 species of fish, 35 species of crustaceans, 26 species of mollusk, 2 species of echinoderms, 2 species of polychaeta and 2 species of other animals. Besides, 10 species of fish eggs & larvae were collected. The speices composition showed seasonal variation during three surveys, e.g., 70 species taxa and 7 fish eggs & larvae taxa in June, 57 species taxa and 7 fish eggs & larvae taxa in August, and 70 species in October. The seasonal changes of dominant and important species were obvious, leading to great changes in community structure. The values of Pielou evenness index, Shannon-Wiener diversity index and resource density all were the highest in summer. There were significant spatial differences in community structure in spring and autumn, but no significant spatial differences in summer.
2. Interannual changes of fishery resources structure in Xiaoqing River Estuary and its adjacent waters from 2009 to 2020
Based on the historical data of fishery resources in August from 2009 to 2020, it was found that the species number of invertebrate taxa and relative resource vaule decreased firstly then increased in this region, while the species number of fish continuously decreased during this time scale. The fishery resource structure also underwent great changes, such as Larimichthys polyactis was less found, and Setipinna tenuifilis replaced by smaller species such as Chaeturichthys stigmatias, Konosirus punctatus and other invertebrate species. Meanwhile, the proportion of invertebrate in total catches kept increasing yearly. The trend of biodiversity indexes was different, which showed that the richness index continued to decline, the diversity index rised firstly then decreased, and the evenness index remained stable after rising.
3. Genetic diversity of O. oratoria population based on COI gene
O. oratoria, widely distributed species in the Northwest Pacific Ocean, is one of the common economic species along the coast of China. In this work, 216 COI gene fragments with a length of 655 bp of this species collected during three surveys were analyzed. The results showed that the content of A + T was significantly higher than that of C + G. In all loci sits, 63 polymorphic loci were detected and 90 haplotypes were defined, including 55 unique haplotypes. The nucleotide diversity was 0.508% and the haplotype diversity was 0.97, indicating a high genetic diversity. By comparing the historical data from 2011 to 2020, a high genetic diversity of O. oratoria in this region had been maintained with an unobvious interannual variation.
4. Genetic diversity of P. trituberculatus population based on COI gene
P. trituberculatus is one of the important species suiting for cultivation and proliferation, which is widely distributed along the coast of China. In this work, 55 mitochondrial COI gene fragments of P. trituberculatus with a length of 684 bp of this species were analyzed. The results showed that the content of A + T was significantly higher than that of C + G. Through sequences alignment, 14 polymorphic loci were detected and 13 haplotypes with 5 unique haplotypes were defined. The nucleotide diversity of P. trituberculatus was 0.215%, the haplotype diversity was 0.80, indicating a medium genetic diversity. Compared with the data in 2006, the genetic diversity of P. trituberculatus population in this region decreased in 2020.
5. Genetic diversity of P. chinensis population based on COI gene
P. chinensis was once an important species for aquaculture and proliferation. This study analyzed 49 mitochondrial COI gene fragments with a length of 684 bp of this species. The results showed that the content of A + T was significantly higher than that of C + G, too. Five polymorphic loci were detected and six haplotypes with 2 unique haplotypes were defined. The nucleotide diversity and haplotype diversity of P. chinensis was 0.071% and 0.50, respectively, indicating a low genetic diversity. The genetic diversity of P. chinensis population showed a variation of decreasing firstly followed by increasing from 1995 to 2020.
In summary, this paper understood the current situation and interannual variation characteristics of fishery resources in Xiaoqing River Estuary and its adjacent waters by the analysis on current data and historical data. Through the analysis, it was found the fishery resources structure had been changed in Xiaoqing River Estuary and its adjacent waters. The dominance and catch ratio of invertebrate taxa increased compare to fish species. We also evaluated the genetic diversity of three common economic species, namely, O. oratoria, P. trituberculatus and P. chinensis, and found their genetic diversity was affected in varying degrees. Among them, the genetic diversity of O. oratoria had maintained at a high level, suggesting the resource protection should be kept in mand of its development and utilization. While, it should be noticed that the genetic diversity of P. trituberculatus and P. chinensis was relatively low, so it was urgent to take reasonable measures to protect and restore the population size and genetic diversity of these two species. |
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