In order to explore the spatial and temporal distribution characteristics of larvae fish resources of the four major Chinese carps in the lower Reaches of the Yangtze River, the abundance differences of larval fishes resources in different river sections were compared, and the spatial and temporal dynamics and occurrence mechanism of larval fish resources in the lower Reaches of the Yangtze River were revealed. The study conducted a monthly survey of larvae fishes in the lower Reaches of the Yangtze River from April to August 2019 by using morphological and molecual biological methods. A total of 107 990 larvae were collected, belonging to 19 species, 2 orders, 2 families, among which 972 were four major Chinese carps, Hypophthalmichthys molitrix being the main species, accounting for 67.28% of the total catch. The results showed that the average monthly abundance of larval in each section segment was 2.57,0.90 and 0.60 ind./100 m3. respectively. The results showed that under the dual effects of river and lake compound ecosystem and estuarine tidal intrusion, the resources of larvae of the four major Chinese carps decreased gradually from Anqing to Nantong section. The study showed that the abundance of larvae fish in the Anqing River section fluctuated month by month since late April, and exploded in June and July. Compared with Nanjing and Nantong, the peak value of Anqing River segment is higher. Kruskal-wallis test showed that there were differences in the lateral distribution of larvae of the four major Chinese carps, which showed that the density of larvae in the nearshore was significantly higher than that in the middle of the river. The analysis of the Pearson test showed that the four major Chinese carps of larvae and juveniles abundance was significantly positively correlated with the water temperature and daily increase rate of and water level (P<0.05). There was a significant positive correlation between the abundance of larvae and juveniles with water temperature and the daily increase rate of water flow in Nanjing section (P<0.05). There was a significant positive correlation between the daily abundance of larvae and juveniles and the daily increase rate of water level and water flow in Nantong section (P<0.05). The results revealed the spatial and temporal distribution characteristics of the early resources of the four fishes in the lower Reaches of the Yangtze River, and concluded that the connectivity system of rivers and lakes plays an important role in the replenishment of domestic fish resources, and provides data support for the regulation of the coastal waterway and the protection of fish habitat in the Yangtze River.
DING Long-qiang
,
LI Jia-sheng
,
XU Dong-po
,
FANG Di’an
,
REN Peng
. Spatial and Temporal Distribution and Influencing Factors of Four Major Chinese Carps Larvae Fish Resources in Lower Reaches of Yangtze River[J]. Resources and Environment in the Yangtze Basin, 2023
, 32(3)
: 478
-486
.
DOI: 10.11870/cjlyzyyhj202303003