Research On Integrated Aquaculture Mode Of Shrimp And Shellfish Pond Based On Ecopath Model

In recent years,with people's attention on environmental protection and food safety,the drawbacks of traditional aquaculture models have gradually emerged.In order to increase the aquaculture output,the early extensive aquaculture model ignoring the carrying capacity of the environment,the model of high-density aquaculture resulting in disease breeding,water quality decline,quality degradation and other phenomena occurred frequently.Optimizing the breeding model,transforming and upgrading aquaculture has become an urgent problem to be solved in the current aquaculture industry.Multi-species comprehensive breeding is based on different nutritional organisms for polyculture.It is widely accepted by aquaculture farmers because of the advantages of strong anti-risk ability,high resource utilization rate,less environmental pollution,higher breeding output,and better breeding quality.Studies have shown that carrying out comprehensive pond breeding is superior to monoculture in terms of economy,ecology,and social benefits,which is a technology worthy of popularization.1. Physiological and metabolic changes of Cyclina sinensis,Tegillarca granosa and Meretrix petechialis at different temperatures: in this study,three types of clams were used as experimental objects.The laboratory still water method and intermittent respiration measurement method were used to study measuring physiological parameters such as ingestion rate,oxygen consumption rate,ammonia excretion rate and faecalegestion rate in different water temperatures.The results showed that except the faecalegestion rate of Meretrix petechialis decreased first and then increased with increasing of temperature.The ingestion rate,oxygen consumption rate and ammonia excretion rate of Cyclina sinensis and Tegillarca granosa all increased with the temperature increased.Oxygen consumption shows an upward trend within the temperature range of 15-25?.Through the study of physiology and metabolism of shellfish,it provides basic data for the study of energetics and ecology,and provides a theoretical basis for the future development of shellfish breeding industry.2. Analysis of two ecological path models which are shellfish only and shrimp shellfish mixed pond ecosystem:Two models were constructed to simulate the pond ecological path model,and a comprehensive quantitative analysis of the pond culture ecosystem was carried out.The results showed that the shellfish pond model was composed of 14 functional groups,and the system is mainly composed of four nutrient levels.The flow of Nutrient I was the largest,accounting for 69.66%of the total system flow.The flows between nutritionals decreased with increasing nutrient level.Each flow of nutrient level were 30.18%,0.15%and 0.01%.The nutrient circulation channels in the ecosystem were mainly dominated by producers in the grazing chain.According to the perspective of nutritional efficiency,the higher EE value of the functional group were0.985 for fishmeal,0.844 for phytoplankton.In the experiment,the total flow of shellfish pond was 37382g/[m~2·year].The food intake was 11344 g/[m~2·year],accounting for30.35%of the total flow,and the total respiration was 8348 g/[m~2·year],accounting for22.33%of the total flow,the total debris production was 17690 g/[m~2·year],accounting for 47.32%of the total flow.The net system production was 15960g/[m~2·year].The shrimp and shellfish pond model is composed of 15 functional groups.The system is mainly composed of five nutritional levels.The nutritional level I had the largest flow,accounting for 71.79%of the total system flow.The flows between nutritionals decreased with the increase of the nutritional level.Each flow of nutrient level were28.01%,0.18%,0.01%and 0.002%.Both the producer chain and the detritus chain have a greater impact on the nutrient circulation of the shrimp and shellfish pond ecosystem.According to the perspective of nutritional efficiency,the higher EE value of the functional group were 0.824 for large zooplankton,0.741 for phytoplankton.The total flow of the pond was 52728 g/[m~2·year].The food intake was 14872g/[m~2·year],accounting for 28.21%of the total flow.The total respiration volume was 9430 g/[m~2·year],accounting for 17.88%.The total debris productivity was 28426g/[m~2·year],accounting for 53.91%.The net system production was 14879g/[m~2·year].However,the pond connectance index and the omnivory index are both very small,indicating that both systems have low maturity and a simple food chain.The results of the nitrogen and phosphorus balance analysis of the simulated pond also showed that,it still remain a lot of energy that had not been utilized and deposited in the bottom sediment of the system.And the energy in shellfish pond was larger than the shrimp shellfish mixed pond.The shellfish pond left about 45.4%nitrogen and 30.2%phosphorus into sediment,while the mixed pond left about 40.7%nitrogen and 17.9%phosphorus.In order to improve the efficiency of the system,it is recommended to increase the density of shrimp culture or introduced a new species which can absorb the nutrients in bottom debritus directly.3. The Ecopath model analysis of commercial large shrimp and shellfish polyculture pond ecosystem:In order to compensate for the uncertainty of simulated ponds,the model construction of large shrimp and shellfish polyculture ponds need to be rebuilt.Relying on the actual situation,a model of 14 functional groups was constructed for the seawater shrimp and shellfish pond.The system is mainly composed of 5 nutritional levels.The flow of nutritional grade I is the largest,accounting for 61.94%of the total flow of the system.The flows between nutritionals decreased with the increase of nutritional levels,which were 37.12%,0.93%,0.01%and 0.00%.Both the producer chain and the detritus chain have a greater impact on the nutrient circulation of the shrimp and shellfish pond ecosystem,which were accounting for 30.51%and 31.43%.According to the perspective of nutritional efficiency,the EE values of small and micro phytoplankton are 0.648 and0.591.The sediment debritus group had higher EE values of 0.987,but the EE values of water detritus group is smaller,0.349.And the artificial bait EE value is 0.551.In the experiment,the total flow of the pond system was 121755g/[m~2·year].The food intake was 46342g/[m~2·year],accounting for 38.06%of the total flow.The total respiration was29813g/[m~2·year],accounting for 24.49%of the total flow.The total debritus production was 45600g/[m~2·year],accounting for 37.45%of the total flow.The net system production of the system is 7333g/[m~2·year].However,the pond connectivity index and the omnivorous index were still very small,indicating that the system is relatively low in maturity and the food chain is simple.The system was needed to improve the utilization rate for a further optimization.Because of a large amount of surplus energy in the system flows into the detritus,based on the current breeding premise,it is recommended to increase the shrimp farming density or get new species for improving the comprehensive breeding efficiency of the system.