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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



associated locally with corals, a very remarkable 

 flora to be discovered in this area. Offshore on 

 the east the sandy Chandeleur Islands with shell 

 ridges shield a shallow, sandy sound. Even 

 marshy islands like Isle au Pitre to the northeast 

 of the delta may be margined by beaches of shells. 

 In the outer delta region at Grand Isle and near the 

 western side of the State south of Lake Calcasieu 

 we again have a sandy shore. Unstable sand 

 subject to wave action is not favorable to growth 

 of algae, and only the more sheltered muddy 

 shores can maintain the flora outlined in the 

 paragraph above. A particular feature of the 

 tidal marsh streams emptying into the northern 

 part of the Gulf may be introduced here. These 

 are reported to support a flora similar to the above 

 near the sea but with the very curious Compsopogon 

 in fresher water. There is no reported work 

 dealing with Louisiana marine algae, but con- 

 siderable collections from the north Gulf coast 

 are now being studied and will add to the details 

 of this account. In salt marshes and tidal lakes 

 on the Calcasieu River the usual limited flora 

 prevails. Weeks Bay and the Canal are similarly 

 but sparsely populated. Lake Pontchartrain on its 

 southeast side is again similar but with more 

 evidence of Cladophora, Ectocarpus, Polysiphonia, 

 and Bostrychia where these are favored by rocks 

 and wharf piles. On the north shore and at the 

 east end, only Rhizoclonium and blue-green algae 

 appear. The tidal marshes at the south delta 

 extension of Chenier Caminada and Grand Isle 

 show the usual flora including Compsopogon; on 

 the outer beaches much Sargassum is washed 

 ashore by storms. In the bay to the west the 

 same flora occurs again, but by virtue of pilings 

 and other firm attachments we have there the 

 Bostrychia flora. In general, because the shores 

 of most of the state are marshy, the opportunities 

 for algal colonization are restricted. 



A great change appears as one crosses the State 

 line into Texas. Only a very short coastal section 

 below Port Arthur is marshy; thenceforth sandy 

 shores face the sea nearly everywhere. Immensely 

 long and narrow peninsulas and islands line the 

 coast with relatively shallow bays behind them. 

 These unstable, sandy, outer shores discourage 

 algae effectively, but in the bays behind and on 

 the rocks of the jetties and other harbor structures 

 a much enhanced (though still not a rich) flora 

 appears, of 60 or more macroscopic species. The 



neighborhood of Galveston and Texas City yield 

 few of these: Ulva lactiica (fig. 48-f), Gelidium 

 crinale var. platycladum, Agardhiella tenera, and 

 Gracilaria confervoides (fig. 50-e) slightly enrich 

 the sparseness of the continued Louisiana type of 

 marsh flora, and of these only the Gelidium really 

 is additional to the Gulf north shore flora and 

 only in its variety among the four seems at all 

 tropical. 



The next group of reported stations centers 

 about Matagorda Bay and its offshoots; Schott, 

 nearly a century ago (Taylor 1941a, 1941b), found 

 it a profitable collecting ground. Here the flora 

 again includes Centroceras, Digenia simplex (fig. 

 50-d), and less distinctive tropical additions. 

 However, the flora between Copano Bay and 

 Corpus Christi Bay is much richer. Uhajasciata, 

 Cladophora Jascicularis (fig. 48-b), Acetabularia 

 (fig. 48-a), Batophora, Padina, Corallina cubensis, 

 Ceramium subfile, and Laurencias greatly ac- 

 centuate the tropical character of the flora de- 

 spite limited suitable substrata. It is not solely 

 this feature which restricts the flora, of course, 

 for the sandy to muddy inner bays might be 

 suitable for Caulerpaceae and Codiaceae, not yet 

 reported from the .State, were it not for unrecog- 

 nized limiting factors. Where muddy, the great 

 shallows behind Padre Island may show an 

 enormous development of an almost leathery blue- 

 green algal flora. On the outer islands Sargassum 

 is washed ashore in conspicuous amounts. This 

 is partly, but not solely, of the pelagic species, for 

 S.Jilipendula and S. pteropleuron are also reported. 

 Otherwise, nothing distinguishes the flora hence 

 to the Mexican boundary. 



The marine flora of the east coast of Mexico is 

 far less known than that of the west coast and 

 both shores much less than the land flora of the 

 central parts of the country. For the east coast 

 this is not hard to understand. South from the 

 Rio Grande extend sandy barrier islands which 

 promise little of botanical interest. With the 

 approach to the shore of hills containing calcareous 

 rock the lime content of the sands increases 

 progressively to Tampico. A little to the north 

 at Punta Jerez limestone rocks outcrop in about 18 

 meters of water and corals occur, so algae may be 

 expected. The calcareous content of the sands, 

 in general, decreases again south of Tampico, but 

 limestone is expected at Lobos Island and other 

 reefs south of Cape Rojo. Lava materials rather 



