Exploring the factors influencing the proliferation of alien Caulerpa species in Cyprus

Alien species, also referred to as exotic or introduced species, are recognized for their potential positive and/or negative effects on the ecosystems into which they have been introduced. The Mediterranean Sea, a semi-enclosed basin, has always been the center of commercial and touristic routes, making it a region potentially threatened by the invasion and establishment of non-endemic species. This region is often described as a biodiversity hotspot, hosting >17,000 species. Among its many subregions, the Eastern Mediterranean Sea (EMED) stands out for the highest number of documented introductions, as a result of its proximity to the Suez Canal. This study focuses on key species, namely Caulerpa taxifolia and Caulerpa racemosa, whose presence and establishment has been acknowledged for years, but whose distribution and proliferation in Cyprus remain widely unknown. By performing statistical analysis on data from grab samples collected around the island at approximately 30 m depth, it was possible to gather information about the factors driving these species’ distribution. In addition, the complex interplay of physiochemical factors driving the proliferation and distribution of alien Caulerpa species was evaluated. The statistical analysis confirmed the hypothesis that both C. taxifolia and C. racemosa thrive in areas closer to ports, even though not exhaustive conclusions can be drawn regarding organic matter content and sediment type. The present results might represent an essential starting point to further investigate into the presence and distribution of alien algal and plant species in the Mediterranean Sea, especially considering that more traditional monitoring methods often fall short in detecting these species. A deeper understanding of the drivers influencing Caulerpa proliferation could improve the ability to predict future colonization patterns, enabling the implementation of measures to mitigate the ecological and economic impact associated to their spread.