As a complementary and symbiotic agro-ecological cycle system, a nature-based integrated rice–fish–duck farming ecosystem was developed in the Honghe Hani Rice Terraces. The main research objective was to evaluate the ecosystem services based on case studies of the Hani integrated rice–fish–duck terraced farming system and determine its potential and its importance as an ecological asset. We developed a valuation model to assess the value of the integrated farming system based on the three aspects of provisioning, regulation and maintenance, and cultural services; we selected eight groups and 10 indictors to evaluate the ecosystem services of the integrated ecosystem in Honghe Hani Rice Terraces was 3.316 billion CNY, of which the provisioning service value was 1.76 billion CNY, the regulation and maintenance service value was 1.32 billion CNY, and the cultural services value was 230.85 million CNY. The evaluation will be useful as a theoretical reference for poverty alleviation policy makers in similar poverty-stricken areas, enabling them to better protect and promote this mode of farming and further promote the protection of the natural environment and cultural heritage alongside the sustainable development of natural resources and human well-being.

Background: An increase in the activity of the pituitary-gonad axis (PG-axis) and gonad development are essential for the onset of spawning migration in teleosts. In the fish Coilia nasus, gonad development and spawning migration up the Yangtze River occurs by the end of each summer. We hypothesized that gonadotropin releasing hormones receptor 2 (GnRH-R2), which together produce a signal that interacts with the PG-axis, may help to regulate spawning migration processes. Results: In this regard, we (1) characterized the gonadosomatic index (GSI) in the anadromous fish C. nasus; (2) analyzed the GnRH-R2 mRNA expression levels in ovary and brain, and concentrations in the serum; and (3) identified the GnRH-R2 protein distribution in the brain and ovaries. We found strong relationships between all of these indices. Conclusions: The results indicate that GnRH-R2 could act together to promote spawning during the anadromous migration. There is some evidence that the GnRH-R2 gene expression levels and protein distributions change in association with the migratory behavior.

Heat shock protein 60 (HSP60) and heat shock protein 10 (HSP10) are important chaperones, which have been proven to have essential roles in mediating the correct folding of nuclear encoded proteins imported to mitochondria. Mitochondria are known as the power house of the cell, with which it produces energy and respires aerobically. In this regard, the obtained HSP60 and HSP10 have typical characteristics of the HSP60/10 family signature. Their mRNA transcripts detected were highest during the developmental phase (in April), while the lowest levels were found in the resting phase (after spawning in late July). Additionally, the strongest immunolabeling positive signals were found in the primary spermatocyte, with lower positive staining in secondary sperm cells, and a weak or absent level in the mature sperm. At the electron microscopic level, immunogold particles were localized in the mitochondrial matrix. Data indicated that HSP10 and HSP60 were inducible and functional in the Coilia nasus testis development and migration process, suggesting their essential roles in this process. The results also indicated that HSP60 may be one indicator of properly working mitochondrial import and refolding in the fish testis. This study also provides an expanded perspective on the role of heat shock protein families in spawning migration biology.

Heat shock proteins play essential roles in basic cellular events. Spawning migration is a complex process, with significant structural and biochemical changes taking place in the adult gonad. To date, the molecular mechanisms underlying migration reproductive biology remain undetermined. In this regard, a full length HSP90AA1 comprising 2608 nucleotides from the anadromous fish Coilia nasus was characterized, encoding 742 amino acid (aa) residues with potential phosphorylation sites. HSP90AA1 mRNA transcripts were detected in all organs, especially in the gonad. Furthermore, the greatest transcript levels were found during the developmental phase, while the lowest levels were found during the resting phase. In addition, the strongest immunolabeling positive signal was found in the primary spermatocyte and oocyte, with lower positive staining in secondary germ cells, and a weak or absent level in the mature sperm and oocyte. Interestingly, HSP90AA1 was mainly located in the cytoplasm of germ cells. These results are important for understanding the molecular mechanism of anadromous migration reproductive biology. In combination with data from other fish species, the result of this present study may facilitate further investigations on the spawning migration mechanism.