The present study of benthic and planktonic organisms of the Corpus Christi and Aransas Bay systems was begun in September, 1972, under the combined aegis of the Texas Water Development Board (TWDB) and the University of Texas Marine Science Institute (UTMSI) through an inter-agency contract (IAC - (72-73) - 893). Prior to the initiation of this project, the TWDB had begun a similar project with the Texas Parks and Wildlife Department (TPWD) for the study of the San Antonio Bay system. The TWDB was also cooperating with the U.S. Geological Survey (USGS) on a hydrographic study of several Texas bays. All of this research is ultimately to aid in determining the need for fresh water inflows into Texas estuarine systems. The present study expanded the estuarine research being coordinated by the TWDB into the most southerly Texas estuarine complex (Figure 1). The objectives of the present study as outlined in the initial contract are similar to the goals of all the research being coordinated by the TWDB and include: 1) the survey of benthic and planktonic communities and their seasonal fluctuations in the Corpus Christi and Aransas Bay systems; 2) the determination of the nutrient budget of these bay systems using data collected under the existing TWDB - USGS cooperative estuarine program; 3) the definition of the primary biological productivity of the Corpus Christi and Aransas Bay systems for the project period; [and] 4) the correlation of nutrient supplies and primary productivity of the estuarine system with seasonal fresh water flows. This report covers the first ten months of the study (September, 1972 - June, 1973). No collections were made during September, 1972, therefore 9 months of data are reported. Due to taxonomic difficulties in the early collection months, a back-log of samples was built up, preventing the inclusion of July and August data in this report. This data will be included in the next annual report. In this report we wish to outline prior pertinent research in this area, to describe our field and laboratory techniques, to present data thus far collected and recorded and to propose analytical methods by which the present data and that to be collected during the remainder of this project may be analyzed. Data collected during the period covered by this report has been stored in the TWDB's Coastal Data System (CDS), a computer operative data storage and retrieval system. The system operates on a 1106 Univac computer system which is located at the TWDB in Austin, Texas.First annual report to the Texas Water Development Board, December 1973.Marine Scienc