Table 2.2. Benthic Macroalgae of Galveston Island Grouped by Maximum Growth Per- 
iods(46). 
Summer-Fall 
Winter-Spring 
Indeterminant 
(not enough date) 
Bryocladia cuspidata 
Ectocarpus siliculosus 
Dictyota dichotoma 
Ceramium strictum 
Petalonia fascia 
Gracilaria foliifera 
Cladophora dalmatica 
Enteromorpha dathrata 
Sargassum fluitans 
Cladophora linum 
Enteromorpha flexuosa 
Sargassum natans 
Polysiphonia gorgoniae 
Enteromorpha lingulata 
Vaucheria sp. 
Polysiphonia denudata 
Polysiphonia tepida 
Spyridia filamentosa 
Chaetomorpha linum 
Erythrocladia subintegra 
Erythrotrichia carnea 
Goniotrichum alsidii 
Achrochaetium sp. 
Enteromorpha prolifera 
Ulva lactuca 
Gelidium crinale 
Bangia fuscopurpurea 
Polysiphonia subtilissima 
taria kurziana (strap-leaf) are currently found in mixed stands (5). Vallisneria has also been found 
in the Chocolate Bay area off West Bay (24). Extensive Ruppia maritima (widgeon grass) beds were 
once located in shallow marginal waters of Trinity Bay and upper Galveston Bay (6-8). East Bay was 
found to be devoid of submerged vegetation (9). Ruppia was also scattered in various embayments 
along lower Galveston Bay and West Bay (10-13). Western West Bay, Christmas Bay and Bastrop Bay 
harbored seagrass beds dominated by Halodule wrightii (shoal grass) and lesser amounts of 
Thalassia testudinum (turtle grass) and Halophila engelmannii (13, 14). The areal extent of 
submerged vegetation has apparently declined from approximately 21 km 2 around 1960 (6-8,12) to 
<1 km 2 by 1979 (15). There have been no studies of seasonal growth or distribution of submerged 
vegetation in the Galveston Bay system, and no actual bay-wide site surveys for species composition 
and distribution. 
Marshes, woodlands and swamps—Emergent vegetation can be classified as salt, brackish or 
freshwater marshes, fluvial woodlands and swamps. These wetlands are large-scale contributors to 
estuarine productivity in terms of particulate matter, nutrients, structure, protection and substrate. 
Salt marshes cover an estimated 140 km 2 (12). Species such as Spartina alterniflora, Batis maritima, 
Salicornia spp. and Juncus roemerianus are most common in the more frequently flooded areas, 
while Borrichia frutescens, Monanthochloe littoralis, Distichlis spicata, Suaeda spp., Iva spp. and 
Aster spp. are less common (Table 2.3). Spartina alterniflora is the dominant plant in subsiding salt 
marshes due to almost constant flooding. Brackish marshes (230 km 2 ; 12) are of moderate salinity 
regimes (1 to 18 ppt) but are flooded by storm tides from the bay and by freshwater inundation from 
rainfall and runoff, thus they have a mixture of vegetation types (Table 2.3). Plants frequently 
occurring in fresher areas include Scirpus maritimus, S. califomicus and S. americanus, Alternath- 
era philoxeroides, Bacopa monnieri, Typha spp., Paspalum lividum and Phragmites australis, 
while plants in the more saline brackish marshes include Spartina patens and S. spartinae, Scirpus 
olneyi and S. maritimus, Paspalum vaginatum, Juncus roemerianus and species from higher salt 
marshes. Lower elevation brackish marshes are dominated by Scirpus, Typha, Eleocharis and 
Bacopa, whereas in higher elevation brackish marshes Spartina spartinae and S. patens are more 
common. Fresh marshes are generally beyond all salt water intrusion except during hurricane surges. 
There are approximately 40 km 2 of fresh marshes, primarily in the Trinity and San Jacinto River 
systems (12). Low fresh marshes are characterized by Typha spp., Scirpus americanus and S. 
25 
