Soft-bottom Marine Benthos

PAN, J.; PRATOLONGO, P.

Marine Biology A Functional Approach to the Oceans and their Organisms

CRC Press - Taylor and Francis

Lugar: Miami; Año: 2022; p. 180 - 210

In the opening to this book, we described the division of the oceans and defined the two-dimensional habitat in which bottom-dwellers are found as the benthic environment, a word that stems from the Greek term benthos, meaning ?depth of the sea?. In turn, the word benthos is used by scientists to refer to the organisms that inhabit benthic habitats, and these, as we will see in this and other chapters, may range from bacteria, to microscopic algae, to rooted vascular plants, to a plethora of invertebrates and vertebrates (e.g., endobenthic, epibenthic and demersal fish, such as pleuronectiforms, myxinids, gunnels, blennies, among others). The benthic realm can be broadly split into two kinds: the so-called ?hard? and ?soft? bottoms. However, geologically speaking, all bottom types are made of solid rock, what varies is the size of particles. As it was introduced in Chapter 1, some oceanic basins, or depositional environments, promote the accumulation of sediment (i.e., rock and mineral fragments of various sizes, origin and chemical composition); after all, a sediment particle is, by definition, matter that settles to the bottom in a fluid medium. On the other hand, several types of hard bottoms are composed of rocky substrates of lithogenic or hydrogenic (abiotic) origin or biogenic nature, that have not been eroded or weathered and provide an extensive, harder, more rigid substrate for settlement or attachment than soft bottoms. These considerably basic differences in bottom type (hard vs. soft) make for very different structuring of benthic communities and different prevalence of ecological and biogeochemical processes. Accordingly, they will be discussed in two different chapters, beginning with this chapter, devoted to soft-bottom benthos, and following with Chapter 10, focused on marine hard-substrate communities