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
Chapter 4
Chapter 4
Division Anthophyta
•Submerged Seagrasses
– About 50 species of seagrasses thrive
throughout the world along subtidal softbottom shorelines. Most seagrasses
reproduce vegetatively via horizontal
rhizomes or sexually via underwater
pollination of tiny flowers followed by fruit
production.
Chapter 4
Division Anthophyta
•Submerged
Seagrasses
a
b
Fig. 4.2 Three common seagrasses from different marine climatic regions:
(a) turtle grass, Thalassia; (b) eel grass, Zostera; and (c) surf grass,
Phyllospadix.
c
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.
Chapter 4
Division Anthophyta
•Emergent
Flowering
Plants
Fig. 4.3 Dense mangal thicket lining a tidal channel (Courtesy of NOAA).
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).
Chapter 4
The Seaweeds
•Structural
Features of
Seaweeds
Fig. 4 The northern sea palm Postelsia (Phaeophyta) is
equipped with a relatively large stipe and a massive holdfast.
Chapter 4
The Seaweeds
•Structural
Features of
Seaweeds
Fig. 4.7 Some large kelp plants of temperate coasts. Each mature plant
develops from a young plant with a single flat blade.
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.
Chapter 4
The Seaweeds
•Photosynthetic Pigments
– Color appearance of Chlorophyta
Fig. 4.12 Intertidal rocks covered with the green alga, Ulva (Courtesy of G. Dudley).
Chapter 4
The Seaweeds
•Photosynthetic
Pigments
– Color
appearance of
Phaeophyta
Fig. 4.13 The brown alga, Fucus, from a rocky intertidal
Chapter 4
The Seaweeds
•Photosyntheti
c Pigments
– Color
appearance
of
Rhodophyta
Fig. 4.14 Mixture of calcareous red algae growing on intertidal
mussels. (Courtesy of G. Dudley).
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.
Chapter 4
The Seaweeds
•Reproduction
and Growth
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.
Chapter 4
The Seaweeds
•Reproductio
n and Growth
Fig 4.17 Generalized growth pattern of a kelp. Punched holes and blue
lines indicate the pattern of blade elongation. Adapted from Mann, 1973.
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.
Chapter 4
Seasonal
Patterns of
Marine Primary
Production
•Fig. 4.20 The seasonal variation of light intensity at the sea surface sets in
motion a cascading series of changes in the photic zone.
Chapter 4
Seasonal Patterns of Marine
Primary Production
•Temperate Seas
– A diatom bloom during the spring, followed
by the successional appearance of lessnumerous dinophytes during the summer, is
the prominent scenario of production in
temperate seas.
Chapter 4
Seasonal
Patterns of
Marine
Primary
Production
•Temperate
Seas
Fig. 4.21 Seasonal fluctuations in the major features of a temperate water
marine primary production system.
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.
Chapter 4
Seasonal Patterns of Marine
Primary Production
•Warm Seas
Fig. 4.23 Comparison of the general patterns of seasonal variations in
primary productivity for four different marine production systems.
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.
Chapter 4
Seasonal Patterns of Marine
Primary Production
•Coastal Upwelling
Fig. 4.24 SeaWiFS image of chlorophyll a concentrations in the upwelling area of
the California Current (left) and the Benguela Current off South Africa and Namibia.
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.
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.
Chapter 4
Global Marine Primary
Production
•Fig. 4.26 Geographic variation of marine primary production made from over three
years of data. (Courtesy of Gene Felderman, NASA/GSFC Space Data Computing Division.)
Chapter 4
Global Marine Primary
Production