scholarly journals Positive feedbacks between bottom-up and top-down controls promote the formation and toxicity of ecosystem disruptive algal blooms: A modeling study

Harmful Algae ◽  
2014 ◽  
Vol 39 ◽  
pp. 342-356 ◽  
Author(s):  
William G. Sunda ◽  
Kyle W. Shertzer
2015 ◽  
Vol 81 (9) ◽  
pp. 3268-3276 ◽  
Author(s):  
Morgan M. Steffen ◽  
B. Shafer Belisle ◽  
Sue B. Watson ◽  
Gregory L. Boyer ◽  
Richard A. Bourbonniere ◽  
...  

ABSTRACTLittle is known about the molecular and physiological function of co-occurring microbes within freshwater cyanobacterial harmful algal blooms (cHABs). To address this, community metatranscriptomes collected from the western basin of Lake Erie during August 2012 were examined. Using sequence data, we tested the hypothesis that the activity of the microbial community members is independent of community structure. Predicted metabolic and physiological functional profiles from spatially distinct metatranscriptomes were determined to be ≥90% similar between sites. Targeted analysis ofMicrocystis aeruginosa, the historical causative agent of cyanobacterial harmful algal blooms over the past ∼20 years, as well as analysis ofPlanktothrix agardhiiandAnabaena cylindrica, revealed ongoing transcription of genes involved in microcystin toxin synthesis as well as the acquisition of both nitrogen and phosphorus, nutrients often implicated as independent bottom-up drivers of eutrophication in aquatic systems. Transcription of genes involved in carbon dioxide (CO2) concentration and metabolism also provided support for the alternate hypothesis that high-pH conditions and dense algal biomass result in CO2-limiting conditions that further favor cyanobacterial dominance. Additionally, the presence ofMicrocystis-specific cyanophage sequences provided preliminary evidence of possible top-down virus-mediated control of cHAB populations. Overall, these data provide insight into the complex series of constraints associated withMicrocystisblooms that dominate the western basin of Lake Erie during summer months, demonstrating that multiple environmental factors work to shape the microbial community.


PsycCRITIQUES ◽  
2005 ◽  
Vol 50 (19) ◽  
Author(s):  
Michael Cole
Keyword(s):  
Top Down ◽  

Author(s):  
Sadari Sadari ◽  
Nurhidayat Nurhidayat ◽  
Rafiqah Rafiqah
Keyword(s):  
Top Down ◽  

Humanisme religius telah mengantarkan pada era kesadaran bahwa peradaban manusia harus memiliki dua arus yang saling menunjang. Selama ini arus balik dalam bidang ekonomi hanya menonjolkan arus balik vertikal atas kebawah (model top down) yang didominasi oleh sistem ekonomi kapitalis dan sosialis, sedangkan di sisi lain mengesampingkan arus balik vertikal dari bawah ke atas (model bottom up) yang didominasi oleh sistem ekonomi syariah, sehingga dampaknya adalah adanya kesenjangan ekonomi yang sangat tajam. Paper ini mewujudkan peran penting, yakni menghubungkan dua arus tersebut secara timbal-balik, yakni mempertemukan arus pertama dengan arus balik kedua, sehingga akan menghasilkan dampak yang positif, progresif, kreatif dan produktif, kemudian pada akhirnya akan dapat meng-optomal-kan ekonomi syariah untuk menciptakan goodgovernance, post goodgovernance secara berkelanjutan, tentunya dengan bantuan peran media kontemporer yang kian update. Ekonomi syariah juga merupakan pilar dan nilai dasar, dari sikap keyakinan dan sikap rasionalitas untuk sanggup menciptakan terwujudnya pemberdayaan dan kesejahteraan sekaligus pengentasan kemiskinan dalam masyarakat di Indonesia.


Sign in / Sign up

Export Citation Format

Share Document