Jenis Dan Struktur Tropik Level Ikan Di Danau Tempe Kabupaten Soppeng Propinsi Sulawesi Selatan

Penelitian berjudul Jenis dan Struktur Trofik Level Ikan di Danau Tempe Kabupaten Soppeng Propinsi Sulawesi Selatan yang dilakukan selama 4 bulan penelitian (Februari, maret, April dan Juni) tahun 2017, bertujuan untuk mengetahui transfer energy di perairan Danau tempe berjalan sesuai dengan sistem jejaring makanan dan manfaat penelitian ini untuk pengelolaan dan pemanfaatan sumber daya ikan yang optimal dan berkelanjutan diperairan Danau Tempe. Hasil penelitian menujukkan bahwa struktur trifik level Beberapa ikan yang tertangkap di perairan Danau Tempe adalah minimum 2 dan maksimum berfarisasi menurut jenis ikan dan waktu pengamatan. Disimpulkan bahwa sumberdaya alam diperairan danau tempe berupa fitoplankton dan zooplankton sebagai produser primer dan consumer primer masih mendukung untuk tingkatan trofik diatasnya yaitu ikan South Sulawesi, which was conducted for 4 months of research (February, March, April and June) in 2017, aims to determine the transfer of energy in the waters of Lake Tempe runs according to the food network system and the benefits of this research for optimal and sustainable management and utilization of fish resources. in the waters of Lake Tempe. The results showed that the trific level structure of some fish caught in the waters of Lake Tempe was a minimum of 2 and a maximum of varying according to the type of fish and the time of observation. It was concluded that the natural resources in the waters of Lake Tempe in the form of phytoplankton and zooplankton as primary producers and primary consumers still support the higher trophic levels, namely fish.

Cascading effects of caffeine intake by primary consumers to the upper trophic level

Secondary metabolites are central to understanding the evolution of plant–animal interactions. Direct effects on phytophagous animals are well-known, but how secondary consumers adjust their behavioural and physiological responses to the herbivore's diet remains more scarcely explored for some metabolites. Caffeine is a neuroactive compound that affects both the behaviour and physiology of several animal species, from humans to insects. It is an alkaloid present in nectar, leaves and even sap of numerous species of plants where it plays a role in chemical defences against herbivores and pathogens. Caffeine effects have been overlooked in generalist herbivores that are not specialized in coffee or tea plants. Using a host–parasitoid system, we show that caffeine intake at a relatively low dose affects longevity and fecundity of the primary consumer, but also indirectly of the secondary one, suggesting that this alkaloid and/or its effects can be transmitted through trophic levels and persist in the food chain. Parasitism success was lowered by ≈16% on hosts fed with caffeine, and parasitoids of the next generation that have developed in hosts fed on caffeine showed a reduced longevity, but no differences in mass and size were found. This study helps at better understanding how plant secondary metabolites, such as caffeine involved in plant–animal interactions, could affect primary consumers, could have knock-on effects on upper trophic levels over generations, and could modify interspecific interactions in multitrophic systems.

SIMULATION OF BIOMASS DYNAMICS IN PLANKTON OF A HIGH-ALTITUDE ANDEAN TROPICAL RESERVOIR IN COLOMBIA.

The understanding of the relationships between the planktonic communities in a reservoir allows us to infer possible changes in the redistribution of matter and energy flows in these systems. This work proposes a dynamic model for the trophic network of the Riogrande II tropical reservoir, which integrates the planktonic trophic chains of detritus and grazing, limiting the prey-predator interactions by introducing the prey meeting factor (pmf). We built a dynamic model of mass balance supported by an extensive bibliographic search. The limitations of consumers and resources were represented simultaneously by means of the pmf. The data used to validate the model were compiled from previous investigations carried out in this reservoir from 2010 to 2013. The values of pmf that we found in each simulation suggest that the top predator can access its main prey in certain concentrations of total phosphorus, with a probability of encounter ranging from 9.3 % to 17.7 %. Our simulations indicate that most of the primary production is poorly used by the primary consumers in the photic zone, however, it enters in the flows of the detrital chain and supports the production of zooplankton almost entirely. According to this finding, the biomass densities obtained in the previous studies can be better explained by the causal relationships assumed in this model.

Phenological Response in the Trophic Levels to Climate Change in Korea

The response of the phenological events of individual species to climate change is not isolated, but is connected through interaction with other species at the same or adjacent trophic level. Using long-term phenological data observed since 1976 in Korea, whose temperature has risen more steeply than the average global temperature, this study conducted phenological analysis (differ-ences in the phenology of groups, differences in phenological shifts due to climate change, differ-ences in phenological sensitivity to climate by groups, and the change of phenological day differ-ences among interacting groups). The phenological shift of the producer group (plants) was found to be negative in all researched species, which means that it blooms quickly over the years. The regression slope of consumers (primary consumers and secondary consumers) was generally posi-tive which means that the phenological events of these species tended to be later during the study period. The inter-regional deviation of phenological events was not large for any plant except for plum tree and Black locust. In addition, regional variations in high trophic levels of secondary consumers tended to be greater than that of producers and primary consumers. Among the studied species, plum was the most sensitive to temperature, and when the temperature rose by 1 °C, the flowering time of plum decreased by 7.20 days. As a result of checking the day differences in the phenological events of the interacting species, the phenological events of species were reversed, and butterflies have appeared earlier than plum, Korean forsythia, and Korean rosebay since 1990. Using long-term data from Korea, this study investigated differences in phenological reactions among trophic groups. There is a possibility of a phenological mismatch between trophic groups in the future if global warming continues due to differences in sensitivity to climate and phenological shifts between trophic levels.

Facebook isn't free: zero-price companies overcharge consumers with data

The emergence of dominant companies that don't charge money to their primary consumers poses serious challenges to current antitrust law around the world. This paper suggests an approach to regulating these ‘zero-price’ companies that considers the data consumers give up to use them as the ‘price’ they pay. The ‘data as price’ model acts as a starting point to assess whether consumers are being ‘overcharged’ by Facebook in the status quo compared to how much data they would give up in a more competitive social media landscape. By surveying thousands of participants and assessing a litany of relevant behavioural considerations, this paper finds that customers are overpaying for Facebook, and that this may come at a serious welfare cost to millions of consumers. While further analysis is warranted, there is substantial cause for concern, and for critical re-evaluation of the standards generally used by antitrust regulators around the world to regulate companies such as Facebook.