The oceans represent a vast area of the planet surface playing a fundamental role. Their physics, chemistry and biology are key elements in the functioning of the earth system setting interconnection between different natural systems (terrestrial, freshwater, estuarine, coastal and oceanic) and providing a range of valuable ecosystem services [19-21]. Their essential role is further noted by the significant fraction of the Earth´s biodiversity that oceans harbor [22]. According with the 33 animal phyla listed by Margulis and Schwartz [23], 32 of them are represented in aquatic environments, with 15 exclusively marine, 17 in marine and non-marine (with 5 of these having more than 95% of their species only in marine environments), existing only …show more content…
Sharing a common environment over a long evolutionary period also allowed the establishment of well-balanced associations between many of these organisms. Several of them survive and live within complex communities and in close association with other organisms both macro (e.g. algae, sponges, ascidians, etc.) and micro (e.g. bacteria, fungi, actinomycetes, etc.) [26-27]. Many of these complex interactions are mediated by chemical signals, which play a crucial role at organizational level in marine environment constituting much of the life sea language. Since several marine species lack eyes and ears, they sense the world via chemical signals, and even species that see and hear rely on chemical cues. Actually, chemically mediated interactions strongly affect population structure, community organization, and ecosystem function, determining feeding choices, foraging strategies, selection of mates and habitats, commensal associations, competitive interactions, and transfer of energy and nutrients within and among ecosystems …show more content…
Thus, substantial investments into stress defense or avoidance strategies may result in a reduction in growth and reproduction [21, 33]. Moreover, the production of these type of compounds have also revealed to be an important weapon for successful invasion of species non-indigenous in new ranges. Recently, the non-indigenous, chemically rich algae Bonnemaisonia hamifera has become one of the most abundant filamentous red algae in Scandinavian waters. The invasion success of this specie seems to be mediated by chemical compound (1,1,3,3-tetrabromo-2-heptanone) production that inhibit the settlement of propagules on its thallus and on surrounding surfaces achieves a competitive advantage over native algae [34]. Also, in the symbiotic interactions established between algae and microorganisms the chemical cues play an important role. The cross-kingdom interactions between they are not only restricted on the exchange of macronutrients, including vitamins and nutrients, but also on infochemicals with different