1. Chapter 4
Marine Plants
Multicellular plants in the sea are dominated by brown and red algae, with green algae and some flowering plants also playing important roles.
Copyright © 2004 Jones and Bartlett Publishers

2. Chapter 4

3. Division Anthophyta Submerged Seagrasses
Chapter 4
Division Anthophyta
Submerged Seagrasses
About 50 species of seagrasses thrive throughout the world along subtidal soft-bottom shorelines. Most seagrasses reproduce vegetatively via horizontal rhizomes or sexually via underwater pollination of tiny flowers followed by fruit production.

4. Division Anthophyta Submerged Seagrasses Chapter 4 a b c
Fig. 4.2 Three common seagrasses from different marine climatic regions: (a) turtle grass, Thalassia; (b) eel grass, Zostera; and (c) surf grass, Phyllospadix.

5. Division Anthophyta Emergent Flowering Plants
Chapter 4
Division Anthophyta
Emergent Flowering Plants
Additional flowering plants, such as marsh grasses and mangals, grow on soft bottoms in the intertidal zone. All types of marine flowering plants host a unique community of organisms within the habitat that they create.

6. Division Anthophyta Emergent Flowering Plants Chapter 4
Fig. 4.3 Dense mangal thicket lining a tidal channel (Courtesy of NOAA).

7. The Seaweeds Structural Features of Seaweeds
Chapter 4
The Seaweeds
Structural Features of Seaweeds
Most large conspicuous plants in the sea are macroalgae (seaweeds and kelps), growing from rocky substrates with their characteristic blades, stipes, holdfasts, and pneumatocysts (in some species).

8. The Seaweeds Structural Features of Seaweeds Chapter 4
Fig. 4 The northern sea palm Postelsia (Phaeophyta) is equipped with a relatively large stipe and a massive holdfast.

9. The Seaweeds Structural Features of Seaweeds Chapter 4
Fig. 4.7 Some large kelp plants of temperate coasts. Each mature plant develops from a young plant with a single flat blade.

10. The Seaweeds Photosynthetic Pigments
Chapter 4
The Seaweeds
Photosynthetic Pigments
The common names of seaweeds often are motivated by their colors, which in turn reflect the various photosynthetic pigments that they contain.

11. The Seaweeds Photosynthetic Pigments Color appearance of Chlorophyta
Chapter 4
The Seaweeds
Photosynthetic Pigments
Color appearance of Chlorophyta
Fig Intertidal rocks covered with the green alga, Ulva (Courtesy of G. Dudley).

12. The Seaweeds Photosynthetic Pigments Color appearance of Phaeophyta
Chapter 4
The Seaweeds
Photosynthetic Pigments
Color appearance of Phaeophyta
Fig The brown alga, Fucus, from a rocky intertidal

13. The Seaweeds Photosynthetic Pigments Color appearance of Rhodophyta
Chapter 4
The Seaweeds
Photosynthetic Pigments
Color appearance of Rhodophyta
Fig Mixture of calcareous red algae growing on intertidal mussels. (Courtesy of G. Dudley).

14. The Seaweeds Reproduction and Growth
Chapter 4
The Seaweeds
Reproduction and Growth
Reproduction in seaweeds can be either vegetative and asexual or complex and sexual.
Sexual reproduction tends to follow three fundamental patterns, all variations of alternating sporophyte, gametophyte, and/or carposporophyte generations.

15. The Seaweeds Reproduction and Growth Chapter 4
Fig 4.16 The life cycle of Laminaria (similar to the cycles of other large kelps), alternates between large diploid sporophyte and microscopic haploid gametophyte.

16. The Seaweeds Reproduction and Growth Chapter 4
Fig 4.17 Generalized growth pattern of a kelp. Punched holes and blue lines indicate the pattern of blade elongation. Adapted from Mann, 1973.

17. Geographic Distribution
Chapter 4
Geographic Distribution
A complex interplay of physical, chemical, geologic, and biologic factors determine the distribution of marine plants on both local and global scales.
In general, brown algae are better adapted to cooler waters, red algae to warmer waters.

18. Seasonal Patterns of Marine Primary Production
Chapter 4
Seasonal Patterns of Marine Primary Production
Fig The seasonal variation of light intensity at the sea surface sets in motion a cascading series of changes in the photic zone.

19. Seasonal Patterns of Marine Primary Production
Chapter 4
Seasonal Patterns of Marine Primary Production
Temperate Seas
A diatom bloom during the spring, followed by the successional appearance of less-numerous dinophytes during the summer, is the prominent scenario of production in temperate seas.

20. Seasonal Patterns of Marine Primary Production
Chapter 4
Seasonal Patterns of Marine Primary Production
Temperate Seas
Fig Seasonal fluctuations in the major features of a temperate water marine primary production system.

21. Seasonal Patterns of Marine Primary Production
Chapter 4
Seasonal Patterns of Marine Primary Production
Warm Seas
Tropical and subtropical waters exist in eternal stratification, with low rates of production and year-round plankton communities that resemble those of temperate regions during summer months.

22. Seasonal Patterns of Marine Primary Production
Chapter 4
Seasonal Patterns of Marine Primary Production
Warm Seas
Fig Comparison of the general patterns of seasonal variations in primary productivity for four different marine production systems.

23. Seasonal Patterns of Marine Primary Production
Chapter 4
Seasonal Patterns of Marine Primary Production
Coastal Upwelling
Rates of net primary production in areas of coastal upwelling are among the highest in the sea, but they are very limited in geographic extent and some of the most important ones are interrupted by El Niño events.

24. Seasonal Patterns of Marine Primary Production
Chapter 4
Seasonal Patterns of Marine Primary Production
Coastal Upwelling
Fig SeaWiFS image of chlorophyll a concentrations in the upwelling area of the California Current (left) and the Benguela Current off South Africa and Namibia.

25. Seasonal Patterns of Marine Primary Production
Chapter 4
Seasonal Patterns of Marine Primary Production
Polar Seas
The seasonal formation and melting of sea ice and tremendous variations in availability of sunlight greatly influences production in polar seas, yet photosynthesis can continue around the clock during a few summer months to create dense populations of phytoplankton.

26. Global Marine Primary Production
Chapter 4
Global Marine Primary Production
Spatial variations in primary production are common, with mid- and high-latitude regions, shallow coastal areas, and upwelling zones being the most prolific, but only during warm summer months when sufficient sunlight is available.

27. Global Marine Primary Production
Chapter 4
Global Marine Primary Production
Fig Geographic variation of marine primary production made from over three years of data. (Courtesy of Gene Felderman, NASA/GSFC Space Data Computing Division.)

28. Global Marine Primary Production
Chapter 4
Global Marine Primary Production