Table 1 Research questions addressed in this manuscript and their motivations

RQ1: What are the key privacy and security challenges in big data ecosystems?

To discover the privacy and security related challenges, which are affecting big data ecosystems the most

RQ2: What are the future research directions in relation to the privacy and security of big data ecosystems?

To explore existing models, techniques, frameworks and methodologies to make big data more secure. To highlight the measures that can be taken in the future to make big data ecosystems more secure and trustworthy