FISHERY BULLETIN: VOL. 69, NO. 4 



Figure 1. — Study area and sampling locations in the 

 Jamaica Beach area of West Bay, Tex. 



For each station, six biological oxygen demand 

 (BOD) bottles (300 ml)— two wrapped with 

 black rubber tape and four unwrapped — were 

 filled (gravity flow) from the 4-liter water sam- 

 ple by inserting the rubber tube down to the 

 bottom of each bottle. About 300 ml of water 

 was permitted to overflow after the bottle was 

 full. Two of the unwrapped bottle samples were 

 fixed immediately for oxygen determination. 

 The remaining bottles were stoppered and sus- 

 pended 15 cm below the surface. The time of 

 sampling was recorded for each station and the 

 bottles were recovered 24 hr later and fixed for 

 oxygen determination. 



Water temperature -( ° C) and turbidity in 

 Jackson turbidity unit — JTU (American Public 

 Health Association, 1962) — observations were 

 made just before the water samples for plankton 

 were taken (Table 1); in.solation was measured 

 with a recording jjyrheliometer located at sta- 

 tion 1. 



Table 1. — Water temperatures and turbidities observed 

 just before each incubation period. 



Dissolved oxygen was measured using a mod- 

 ified Winkler method (Carritt and Carpenter, 

 1966) . Oxygen determinations were made with- 

 in 3 hr after fixing the water samples. Changes 

 in dissolved oxygen were converted to changes 

 in organic carbon using the relation formulated 

 by Ryther ( 1956) : 1.0 mg oxygen is equivalent 

 to 0.30 mg carbon. 



Net production (NP), respiration (R), and 

 gross production (GP) were determined using 

 the carbon values from the initial (/), light (L), 

 and dark (D) bottle values as follows: 



NP = L — I,R = I — D, and GP = NP + R. 



ENVIRONMENTAL AND 

 HYDROLOGICAL DATA 



Surface water temperature varied no more 

 than 1.5° C between stations on any sampling 

 date and no more than 3° C between dates at 



830 



