Kelp forests are extensive underwater habitats characterized by the presence of large seaweeds that form canopies over the seafloor. Kelps are typically competitively dominant and long-lived, with some species reaching tens of meters in height. They grow very fast and rapidly produce a vast amount of biomass (Krumhansl & Scheibling, 2012; Mann, 1973) and create a three-dimensional structure that alters their surrounding physical environment (Eckman, Duggins, & Sewell, 1989; Reed & Foster, 1984; Wernberg, Kendrick, & Toohey, 2005). As a consequence, kelp forests provide habitat, shelter, and food to a huge number of associated species (Teagle, Hawkins, Moore, & Smale, 2017). Kelp forests dominate along approximately one-quarter of the world’s coastlines, in Arctic and temperate latitudes in both hemispheres (Krumhansl et al., 2016). Their diverse variety of habitat types (Fig. 3.1) delivers a broad range of valuable ecosystem services (e.g., Bennett et al., 2016). Kelp forests show global declines and, like so many other marine ecosystems, they are under pressure from the direct and indirect effects of anthropogenic activities. These processes have been driving rapid changes in the distribution and abundance of many kelp forests globally over the past couple of decades, and in many instances declines in kelp forests threaten ecosystem services vital to human well-being (Filbee-Dexter & Scheibling, 2014b; Filbee-Dexter & Wernberg, 2018; Krumhansl et al., 2016; Steneck et al., 2002). There is some debate about what constitutes ‘kelp’ (Fraser, 2012). Some reserve the term only for species of Laminariales whereas others use it more broadly to also include fucalean and other large seaweeds (Fraser, 2012). Here, we focus predominantly on subtidal laminarian kelps (Fig. 3.1) because these species constitute a well-defined group with respect to taxonomy, life cycles, ecology, distribution, and socioeconomic importance. However, ‘kelp’ is a non-taxonomic name and many other types of seaweeds provide similar functions (Bolton, 2016), with no imperative or precedence for limiting its use to the Laminariales per se (Fraser, 2012).
|Titel||World Seas: An Environmental Evaluation : Ecological Issues and Environmental Impacts|
|Status||Udgivet - 2019|