selective deposit feeders and omnivores. Non-selective 

 deposit feeders (e.^., polychaetes) process bulk 

 sediment by extracting organic matter from the mud. 

 Selective deposit feeders (e.^., moUusks) usually have 

 tentacles to pick and choose specific particles of 

 material for ingestion. Omnivores (e.^., edible shrimp, 

 Petiaeus sp.) eat detritus, microphytes or any small 

 animals that they can catch. These benthic animals, in 

 turn, provide prey items for many other estuarine 

 animals, particularly fish. 



Algal Mat 



vMgal mats are unusual features of the supratidal zone 

 that occur in some locations within the Nueces Estuary 

 and Delta (Figure 2-10). They occur when rain, wave 

 surges or higher tides collects in low spots near the 

 shore, often in areas with higher elevation than salt 

 marshes. The trapped water is very shallow, and often 

 becomes quite warm and saHne with solar radiance and 

 evaporation. However, these conditions allow a bloom 

 of photosynthetic bacteria (cyanobacteria, or blue- 

 green algae) that live on the sediment surface. These 

 producers are very important to die bay ecosystem 

 because they have the abiUty to fix atmospheric 

 nitrogen (Nt) into forms more usable by other 

 producers and bacteria like ammonia (NHj), nitrate 



Figure 2-10: View of algal mat habitat near South 

 Lake. This mat is comprised of colonies of filamentous 

 blue-green, unicellular green, flagellated and 

 diatomaceous algae, bacteria and a minor assemblage of 

 worms, crustaceans and ciliates. The vegetation is 

 approximately 6 to 10 inches tall. 



Photo courtesy of U.S. Fish and Wildlife Service. 



(NOj) or nitrite (NO2). When this material is 

 transported back into the bays, it represents a nutrient 

 spike that can enhance primary productivity in the 

 estuary. However, aside from the cyanobacteria, there 

 are not many species endemic to the relatively harsh 

 conditions of the algal mats. 



HISTORY OF THE NUECES ESTUARY 

 AND DELTA 



Just over a century ago. Dr. A.C. Peirce, a Bostonian 

 naturalist intent on collecting bird species from the 

 coastal regions of Texas, traveled to the Corpus Chrisd 

 area. At that time (about 1890), Corpus Christi was 

 still a primitive setdement on the western bayfcont, 

 accessible to the mainland by ferry across the Nueces 

 near San Patricio, by fording El Rincon at Indian Point 

 or by rail (Ward 1998). Peirce's book (1894) describes 

 the travels of he and his guide (a local Corpus Christi 

 resident and hunter), and includes several accounts of 

 excursions into parts of the Nueces Estuary, 

 particularly die Nueces Delta and upper bay. Although 

 it reflects the values and judgements of the late 19th- 

 century, the work pro\'ides a picture of the study area 

 prior to many of the human activities that have 

 changed it since: 



"About a week after my arrival at Corpus Christi,... 

 we started for the Nueces Flats. Our road was mostly 

 through a country covered with a low growth ofmesquite 

 andweesatche [sic] brush, where pasture fences were 

 much more numerous than houses, of which we saw 

 few. . .. The land all about this part of the country is 

 divided up into pastures containing many square miles 

 each, which are occupied by thousands of sheep, goats, 

 horses and neat cattle. . .. Twelve or fifteen miles from 

 our starting place, we left the beaten road, and traveling 

 four or five miles over a rough and hilly stretch of land, 

 crossed the Nueces River and camped a few miles 

 beyond 



"Above the function of the river with the bay is a large 

 area of low marshy surface; this is the Nueces Flats, 

 which include several thousand acres of land and water 

 In hundreds of places on the north side of the river, the 

 earth is depressed below the level of the stream; and 

 these depressions, filled with water, are, in places, only 



Chapter Two ♦ 2-11 



