The male and female gametophytes of Saccharina japonica ‘Dongfang No.7’ were cultured at different temperatures, photoperiods and nitrogen concentrations to observe the development of gametophytes and explore the optimum environmental conditions for the formation of gametophyte oogonium, ovulation and young sporophyte. The results showed that temperature, photoperiod and nitrogen concentration had significant effects on the development of gametophyte. The rate of gametophyte development at 12 ℃ and 15 ℃ (60%-70%) was significantly higher than that at other temperature groups. At 20 ℃, the gametophyte was in the vegetative growth stage without development. The rate of gametophyte development (80%) in 10L∶14D group was significantly higher than that in other photoperiod groups, followed by that in 6L∶18D group, but the length of young sporophyte in this condition was significantly lower than that in other photoperiod groups. When the concentration of N was 2 mg/L and 4 mg/L, the final development rate was more than 75%, and the sporophyte accounted for about 70%, which was significantly higher than other groups. This study provides theoretical basis and data support for artificial breeding of gametophyte of S.japonica ‘Dongfang No.7’.

In order to investigate the common fish diseases in indoor culture of large yellow croaker (L.crocea), this study reports the occurrence of scuticociliatosis, a parasitic disease, on the surface of L.crocea in a laboratory circulating water recirculation system. The histopathological analysis of skin, liver and muscle of L.crocea was carried out to explore the pathogenic mechanism of scuticociliatosis. At the same time, in order to further identify the body surface parasitic Scuticociliatida ciliates of L.crocea, the pathogen was isolated, and the morphological characteristics of Scuticociliatida ciliates were analyzed by in vivo formaldehyde fixed microscopic observation and scanning electron microscope observation. The results revealed the presence of whitening symptoms on the head, skin, and fin base of L.crocea. Gill cover congestion and severe cases of white massive skin ulceration were observed, along with the infestation of a significant number of Scuticociliatida ciliates. Notably, no apparent pathological alterations were detected in the body tissue. Histopathological analysis showed that the skin and subcutaneous tissue were the main sites of infection with Scuticociliatida ciliates. Tissue necrosis, cytolysis and increase of inflammatory cells occurred in most areas of muscle tissue. Myofibril was obviously broken and muscle fiber space was enlarged, while the boundary between liver tissue cells was not obvious, the central vein was oppressed, mononuclear cells increased and parenchyma cells enlarged. It was observed that the body of the pathogen was mainly slightly pointed at the top, blunt and round at the back end of the body, and contained an obvious telescopic vesicle as well as a long flagellum. The pathogen was identified as Pseudocohnilembus persalinus by morphology. Taken together, the histopathological results showed that the Scuticociliatida ciliates could infect the body surface tissue of L.crocea, resulting in loss of protection and resistance. At the same time, this study can provide a certain reference basis for indoor healthy culture of L.crocea.

In order to investigate the current situation of marine health food industry in Shandong Province, a systematic analysis was carried out on the function distribution, raw material sources and dosage form distribution of the approved marine health food in Shandong Province, according to the data of domestic health food database published on the website of the State Administration for Market Regulation.The existing problems of marine health food industry in Shandong Province were summarized, and the countermeasures and suggestions for its development were put forward.