Use of fatty acids as tracer of organic matter input associated with level of land urbanization

Ecofisiologia e relações tróficas de elasmobrânquios: biomarcadores como ferramentas para conservação

“…However, it is important to note that urban sharks had higher C18:1n9/C18:1n7 ratios (indicator for carnivory/piscivory, , suggesting that urban sharks could be primarily consuming fishes, while non-urban sharks could be consuming a broader diversity of prey types, including crustaceans and mollusks . Given that C18:1n9 is one of the main components of domestic sewage, it is possible that these could be transferred though the food web in urbanized habitat (Jiménez-Martínez et al, 2019). As predicted, urban sharks had higher percentages of heterotrophic bacterial markers (ΣBFA-OFA, including C17:0).…”

“…Corroborating the possible influence of domestic and industrial wastewater on nutrients, higher percentages of SFA (C16:0 and C18:0) were found in sharks sampled in high urbanized area. These fatty acids are the main components of domestic sewage, and can be transferred directly or indirectly to consumers Jiménez-Martínez et al, 2019). Similarly, higher percentages of SFA were found in nurse sharks sampled within high urbanized area .…”

“…Other ecological and physiological phenomena may explain the difference found in nutritional quality between urban and non-urban sharks. First, it is possible that SFAs are transferred directly or indirectly from domestic sewage, since C16:0, as well as C18:1n9, have been found to be the main components of domestic sewage, and therefore, highly correlated to urbanization Jiménez-Martínez et al, 2019). Second, SFAs are resistant to peroxidation and PUFAs are highly damaged due to induced oxidative stress in urban animals living under environmental stress .…”

“…We also expected to find that blacktip sharks sampled in high urbanized areas would exhibit higher proportions of saturated and bacterial fatty acids, which are markers for domestic sewage effluent (e.g. Jiménez-Martínez et al, 2019;. Additionally, because sharks were sampled in areas exposed to different freshwater input, we expected to find spatial variation in omega-6 PUFA (Parrish et al, 2000), a terrestrial fatty acid marker (Fig.…”

“…We also expected to find higher proportions of saturated and bacterial fatty acids in urban sharks, as these biomarkers are highly correlated with urbanization, for example due to domestic sewage effluent (e.g. Jiménez-Martínez et al, 2019).…”