Effects of trophic levels (chlorophyll and phosphorous content) in three different water bodies (urban lake, reservoir and aquaculture facility) on gill morphology of Nile tilapia (Oreochromis niloticus )

2012 ◽  
Vol 29 (3) ◽  
pp. 573-578 ◽  
Author(s):  
J. C. Shimada Borges ◽  
A. B. B. Salimbeni Vivai ◽  
P. C. Branco ◽  
M. Silva Oliveira ◽  
J. R. Machado Cunha da Silva
1991 ◽  
Vol 48 (2) ◽  
pp. 183-190 ◽  
Author(s):  
James S. Diana ◽  
Daniel J. Dettweiler ◽  
C. Kwei Lin

The trophic cascade hypothesis holds that an increase in fish biomass causes a decline in food organisms of the fish, which cascades down to regulate lower trophic levels by altered consumptive demands. This hypothesis was evaluated by stocking Nile tilapia (Oreochromis niloticus) at densities of 0, 1, 2, or 3 fish/m3 in triplicated 220-m3 ponds near Bangkok, Thailand. All ponds were fertilized with 500 kg chicken manure∙ha−1∙wk−1. We measured phosphorus, nitrogen, chlorophyll a, primary productivity, zooplankton abundance, and fish yield in all ponds. Increased stocking density resulted in decreased adult fish growth but similar yields among the three density treatments. Regressions relating the abundance of each trophic level to the next higher trophic level were either positive or nonsignificant, which is contrary to trophic cascade predictions. Zooplankton became significantly more dense over time in fishless ponds than the other three treatments, but no other trophic level differed among treatments. These results indicate that presence of fish had a significant effect on zooplankton in ponds, but biomass of fish or abundance of zooplankton did not significantly affect other trophic levels.


2019 ◽  
Vol 133 (2) ◽  
pp. 141-145 ◽  
Author(s):  
E Soto ◽  
K Shahin ◽  
JJ Talhami ◽  
MJ Griffin ◽  
A Adams ◽  
...  

Author(s):  
Arne A Ratulangi ◽  
Reiny Tumbol ◽  
Hengky Manoppo ◽  
Henneke Pangkey

This study aims to apply vaccination against bacterial disease. The purpose of vaccination is to trigger the immune respone both non-specific and specific of fish against bacteria Motile Aeromonas Septicaemia (MAS) caused by Aeromonas hydrophila. The vaccination for fish with different ages: 2-3 weeks and 5 weeks were done using immersion method. The fish were re-vaccinated (booster) after two weeks of the first vaccination. The survival rate was < 50 % for juveniles 2-3 weeks and > 50% for juveniles 5 weeks. Survival rate for juveniles 5 weeks was higher than juveniles of 2-3 weeks. This shows that organs of juveniles of 5 weeks were more complete than the 2-3 weeks juveniles. The age of fish is one of the important factors for successfully vaccination. Penelitian ini bertujuan untuk melakukan penerapan vaksinasi terhadap penyakit bakterial. Vaksinasi ditujukan untuk merangsang respon kekebalan non- spesifik dan spesifik pada tubuh ikan terhadap penyakit Motile Aeromonas Septicaemia (MAS) yang disebabkan oleh bakteri Aeromonas hydrophila. Vaksin diberikan pada benih ikan nila yang berbeda umur yaitu 2-3 minggu dan 5 minggu dengan menggunakan metode perendaman. Ikan divaksinasi ulang (booster) setelah 2 (dua) minggu dari vaksinasi yang pertama. Prosentase kelangsungan hidup < 50 % untuk benih umur 2-3 minggu dan > 50% untuk benih umur 5 minggu. Jumlah kematian benih umur 2-3 minggu lebih tinggi dari 5 minggu. Hal ini menunjukkan bahwa fungsi organ benih umur 5 minggu telah lebih lengkap dari pada benih umur 2-3 minggu. Umur ikan merupakan salah satu faktor penting penentu keberhasilan suatu kegiatan vaksinasi.


2013 ◽  
Vol 37 (10) ◽  
pp. 1460 ◽  
Author(s):  
Huaping ZHU ◽  
Maixin LU ◽  
Zhanghan HUANG ◽  
Fengying GAO ◽  
Xiaoli KE ◽  
...  

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