About this Research Topic
The marine environment is extraordinarily diverse and made up of a large number of different marine habitats identified by physical structures or specific environmental conditions. However, habitats are not discrete, as organisms living in one habitat may interact with other habitats within an ecosystem. Interspersed between frequently studied, accessible habitats are more cryptic, isolated habitats requiring unique physiological and morphological adaptations and possessing high levels of endemic and transient biodiversity. It is our objective to bring to light these often overlooked and underestimated habitats and their impact upon the surrounding ecosystems.
Many of these habitats are poorly studied, with less data than the ocean depths, restricted by assess and inadequate research methods or characterized by habitat complexity. The biodiversity of rocky reefs in temperate and cold waters, marine caves and small cryptic habitats at the bottom (crevices and holes in bedrock, reef cavities or interstitial spaces among cobble or boulder layers), areas of submarine groundwater discharge, etc., is still unexplored, hidden primarily due to obscurity of locations of the habitats and inadequate research methods. E.g., limited available data are indicating that deeper steep and vertical slopes of rocky reefs, particularly in the Mediterranean, are rich in biodiversity. Covered by coralligenous formations that are complexes of biocoenoses, these habitats are characterized by complexity and heterogeneity, yet relatively overlooked as a result of inaccessibility. These reefs extend to depths deeper than 30 m, placing them out of range of conventional visual census methods. A few published studies on small cryptic habitats at the bottom highlight the largely unstudied ecological relevance of the cryptobenthic fish community as revealed by an unexpected high diversity and the numerical dominance of some species which previously were considered rare. There is a similar dearth of data on other hidden habitats, such as isolated regions receiving subterranean groundwater discharge and marine caves where, descriptive or comparative studies on biodiversity of these habitats are scarce or non-existing. As part of the coastal environment, these habitats are subjected to major environmental stresses, mainly anthropogenic. Potential impacts of these stressors on hidden habitats are difficult to assess because of the lack of baseline data and incomplete sampling.
Thus, this research topic is being focus on description of the biodiversity of these hidden habitats on all trophic levels and on identification of environmental drivers of associated species, as well as on habitat functional role not only on its own biodiversity but also of surrounding coastal ecosystems. Accordingly, the new research techniques used for sampling of those habitats should be given importance. Studies to examine the contribution of hidden habitats to coastal productivity or to characterize the biodiversity differences between areas varying in rates of depth, salinity, temperature and other characteristic variables associated with these habitats, will be equally considered.
This research topic will serve to identify biodiversity of so far hidden habitats and to determine how they are interconnected with coastal ecosystem, marine and terrestrial, and will also provide baseline data to begin to address the impact of development on coastal ecosystems.
Keywords: Biodiversity, deep reefs, marine caves, groundwater discharge, coastal habitats
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