all of the world’s oceans. Globally, rhodoliths fill an
important niche in marine ecosystems, serving as transitional habitats between rocky substrates and barren sedimentary areas. Under favorable preservation conditions,
rhodoliths can be the predominant contributors of carbonate sediments, often forming rudstone or floatstone depositional beds consisting of large fragments of rhodoliths
contained in grainy matrices. Although they are rolled
by infrequent storms, rhodoliths nevertheless provide
a three-dimensional micro-habitat onto which a wide variety of species attach, including other algae, corals, and
commercial species such as clams, oysters, and scallops.
Rhodoliths are a common feature of modern and ancient
carbonate shelves worldwide. Fossil rhodoliths commonly are used to derive paleoecological and paleoclimatic information and rhodolith communities contribute
significantly to the global calcium carbonate budget.
Quantitative submersible studies (Littler et al., 1991)
of deep-water rhodolith development, distribution,
abundance, and primary productivity, at sites of both
active formation and breakdown, provided the following
detailed case-study. The 1.27 km
2 upper platform (67–
91 m deep) of a $1,000-m high Bahamian seamount
(San Salvador Seamount) averaged 95.8% cover of
rhodoliths, contributing an impressive 391 tons of organic
carbon per year to deep-sea productivity (tropical storms
cause the rhodoliths to roll at this depth). The predominant
crustose coralline alga was acclimated to extremely low
light ranges, with an extremely narrow PI curve (photosynthesis vs. irradiance) of net primary productivity
(0.005 to slightly beyond 0.24 µmol per meter square
per sec of photosynthetically active radiation). Horizontal
platform areas contained up to five-deep accumulations
(about 45 cm thick) of rhodoliths, with their visible planer
(two-dimensional) crustose algal cover (68.5%) being
composed of 41% Lithophyllum sp., 14.9% mixed crustose corallines, and 12.6% Peyssonnelia sp. The platform
rhodoliths also contained an average 25% cover of the
Algae, Coralline, Figure 1 Spectrum of articulated (jointed, geniculate) coralline algal forms.
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ALGAE, CORALLINE
important niche in marine ecosystems, serving as transitional habitats between rocky substrates and barren sedimentary areas. Under favorable preservation conditions,
rhodoliths can be the predominant contributors of carbonate sediments, often forming rudstone or floatstone depositional beds consisting of large fragments of rhodoliths
contained in grainy matrices. Although they are rolled
by infrequent storms, rhodoliths nevertheless provide
a three-dimensional micro-habitat onto which a wide variety of species attach, including other algae, corals, and
commercial species such as clams, oysters, and scallops.
Rhodoliths are a common feature of modern and ancient
carbonate shelves worldwide. Fossil rhodoliths commonly are used to derive paleoecological and paleoclimatic information and rhodolith communities contribute
significantly to the global calcium carbonate budget.
Quantitative submersible studies (Littler et al., 1991)
of deep-water rhodolith development, distribution,
abundance, and primary productivity, at sites of both
active formation and breakdown, provided the following
detailed case-study. The 1.27 km
2 upper platform (67–
91 m deep) of a $1,000-m high Bahamian seamount
(San Salvador Seamount) averaged 95.8% cover of
rhodoliths, contributing an impressive 391 tons of organic
carbon per year to deep-sea productivity (tropical storms
cause the rhodoliths to roll at this depth). The predominant
crustose coralline alga was acclimated to extremely low
light ranges, with an extremely narrow PI curve (photosynthesis vs. irradiance) of net primary productivity
(0.005 to slightly beyond 0.24 µmol per meter square
per sec of photosynthetically active radiation). Horizontal
platform areas contained up to five-deep accumulations
(about 45 cm thick) of rhodoliths, with their visible planer
(two-dimensional) crustose algal cover (68.5%) being
composed of 41% Lithophyllum sp., 14.9% mixed crustose corallines, and 12.6% Peyssonnelia sp. The platform
rhodoliths also contained an average 25% cover of the
Algae, Coralline, Figure 1 Spectrum of articulated (jointed, geniculate) coralline algal forms.
22
ALGAE, CORALLINE