former. 



Biological enhancement of particulate matter can be 

 recognized by a variety of characteristics. The concentrations 

 of biologically-derived compounds, such as protein or ATP, may be 

 elevated. Ratios of chemical constituents, C/N, ATP/C, 

 chlorophyll a/total pigment, will indicate the degree of 

 degradation of the organic material present. Numbers of 

 bacteria, autotrophic and heterotrophic nanoplankton, 

 microzooplankton ( >35 u m) and mesozooplankton will be increased. 

 Finally, biological rates, as indicated by respiratory electron 

 transport rates (Packard, 1986), will be elevated. Although 

 these measurements can document biological enhancement, they 

 cannot distinguish the mechanisms, which will be a combination of 

 in situ growth, vertical (sinking from surface or resuspension 

 from bottom) and horizontal transport with physical trapping, and 

 migration of organisms. 



METHODS 



Sampling Methods 



In 1985 water samples were obtained using the valve in the 

 aft compartment of the Johnson Sea-Link submersible. It was 

 connected via Tygon tubing to the robotic arm where a Sea Tech, 

 Inc. transmissometer was also mounted. With the submersible 

 sitting on the bottom and facing into the current, the robotic 

 arm was positioned at various depths above the bottom, a reading 

 was obtained with the transmissometer and water samples were 

 collected in bottles in the aft compartment. To obtain samples 

 at greater heights above the bottom, the submersible was slowly 

 raised and then held stationary at the desired depth. Samples 

 were filtered or preserved as soon as the submersible was back on 

 board the ship. 



In 1986 the submersible became unavailable at the last 

 minute and the R. V. Oceanus was substituted. Two methods of 

 sampling from the surface were utilized. A CTD with a 

 transmissometer and a rosette with 24 5 1 Niskin bottles was used 

 for measurements from the surface to 5 m above the bottom. 

 (Identified by CTD in all figures). Although it could be used to 

 obtain profiles in a very short time, the sample volumes were not 

 adequate for more than a few analyses (chlorophyll, protein, 

 heterotrophic and autotrophic nanoplankton) and it could not be 

 used near enough to the bottom. To obtain large sample volumes 

 between 2 and 20 m above the bottom, a bottom tripping rosette 

 with 3 30 1 Niskin bottles was constructed (Identified by R in 

 all figures). However, the rosette could sample only one depth 

 at a time. Approximately 1-h elapsed between each cast at a 

 particular station in order to process the water. Samples were 

 filtered or preserved immediately. 



184 



