Estuarine Seagrasses

Publikation: Bidrag til bog/antologi/rapportBidrag til bog/antologiForskning

  • Renee K. Gruber
  • Cassie Gurbisz
  • Borum, Jens
  • W. Michael Kemp
Seagrass and other submersed vascular plants are iconic and important primary producrs in estuarine habitats. They play key roles in coastal ecosystems such as supporting fisheries, stabilizing the sediment, squestering carbon, utilizing dissolved nutrients, serving as a food source for higher trophic orders, and providing cultural benefits to society (Barbier et al. 2011). Seagrasses are a diverse group of monocyteledonous flowering plants that can grow in marine and estuarine environments (Figure 5.1). All species have belowground rhizomes from which root and leaf bundles are formed. Many freshwater vascular plants have apical meristems that enable them to grow toward the light at the water's surface. In contrast, all seagrasses have basal leaf meristems that continuous replacement of old leaves with new clean leaves.
Estuarine seagrasses have terrestrial ancestors that invaded the marine environment at different times during their evolution (Les et al. 1997). Accordingly, seagrass species have different origins and are referred to as a polyphyletic group, where some species are more closely related to freshwater vascular plants than to other seagrasses. As a result of this evolutionary history, the morphology of seagrasses is quite diverse (Figure 5.1), ranging from small shoots (on the order of centimeters) with elliptic leaves to larger plants with broad, linear leaves (on the order of meters).
The evolution of terrestrial plants in the marine environment created a number of unique physiological properties of seagrasses (Olsen et al. 2016). Terrestrial plants are susceptible to desiccation and have evolved hairs or other leaf structures to reduce moisture loss, whereas submersed plants have lost most of these protections. The leaf cuticle (a waxy outer covering that helps prevent desiccation) is reduced in seagrasses compared to terrestrial plants. One advantage of this evolutionary changeis that seagrasses can efficiently extract nutrients from the water column in addition to taking up belowground nutrients through their root systems (Hemminga and Duarte 2000). Submersed plants lack the ability to transpire from leaves, a process used by terrestrial plants to drive internal transport of solutes, and instead use the energy-consuming process of root pressure (Pedersen and Sand-Jensen 1993). Seagrasses have reduced structural tissues compared to terrestrial plants, and instead maintain their structure and buoyancy with air-filled lacunae in their leaves. The flexibility and strength of seagrass leaves is an important morphological feature necessary for withstanding the drag forces induced by waves and currents (Koch 2001).
Bidragets oversatte titelEstuarine havgræsser
TitelEstuarine Ecology
RedaktørerByron C. Crump, Jeremy M. Testa, Kenneth H. Dunton
Antal sider20
ForlagJohn/Wiley & Sons, Inc. John/Wiley & Sons Ltd.
ISBN (Trykt)978-1-119-53465-5
StatusUdgivet - 2023

ID: 338422814