Epiphytic (living on plants) microalgae are treated here as a 
group separate from other benthic algae because of their apparent 
importance in food webs in other Florida estuarine systems (Fry 1984), 
and because those found growing on seagrass leaves in Tampa Bay have 
received some study (Dawes 1985). The most common epiphytes are species 
of Champia , Lomentaria , Polvsiphonia , Acrochaetium , Fosliella , Hypnea , 
Spyridia , Cladosiphon . Ectocarpus and Cladophora . The possible 
importance of epiphytic algae in the food web and the general health of 
seagrasses in a eutrophic estuary like Tampa Bay are discussed later. It 
is sufficient to note here that the abundant caridean shrimp and 
amphipods found in Tampa Bay seagrass meadows have been shown elsewhere 
to depend heavily on seagrass algal epiphytes as a source of food (Orth 
and Van Montfrans 1984). It is likely that the same dependence would be 
found here. 
Macroalgae are abundant in Tampa Bay, and the 221 identified 
species from the bay represent a greater diversity than that reported for 
any other estuary in Florida (Dawes 1985). Red and green algae 
predominate, with brown algae being more abundant in the winter and early 
spring, although still not dominant. 
Most studies of macroalgae in the bay have been taxonomic or 
physiological in nature (Dawes 1985); have focused on the overabundance 
of certain pollution indicator species (Ulya spp., Gracilaria spp.) which 
cause aesthetic problems (FWPCA 1969); have been implicated in the 
elimination of seagrass meadows from certain parts of the bay (Guist and 
Humm 1976); or have anecdotally reported consumption of macroalgae by 
manatees (Lewis, Carlton and Lombardo 1984). The FWPCA (1969) studied 
the abundance and distribution of macroalgae in Hillsborough and Old 
Tampa Bay to determine the source of odor problems reported by residents 
along the western shore of Hillsborough Bay. The study concluded that 
the odors were caused by excessive nutrient concentrations which led to 
massive blooms of the macroalga Gracilaria tikvahiae . This species, in 
turn, was killed by normal salinity reductions during times of heavy 
rainfall and decayed to produce the odor. 
Rates of primary production by Tampa Bay macroalgae, of 
approximately 70 g C/m 2 /yr, have been measured in both laboratory and 
field experiments (Hoffman and Dawes 1980; Dawes 1985). The data are 
very sparse, and much additional work is needed, especially seasonal 
field measurements. 
Seagrasses are submerged flowering plants with true roots and 
stems, and are quite different from "seaweeds" (macroalgae), which are 
nonflowering algal species without true roots. Lewis, Durako, Moffler 
and Phillips (1985) reported that five of the seven species of seagrass 
known from Florida are found in Tampa Bay: Thalassia testudinum (turtle 
grass); Svrinqodium filiforme (manatee grass); Halodule wrightii (shoal 
grass); Ruppia maritima (widgeon grass); and Halophila engelmannii (star 
grass). 
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