47 



thousands of gallons) aay still be of sufficient quantity to support an 

 abundant and diverse asseablage of living organisas. 

 It aay be taken as a general rule that, vlth rare exception, virtually 

 all vessels have soae ballast water aboard all of the tiae. 

 D. S. Custoas and port records do not noraally record ballast water 

 aK>unts when vessels are "in ballast" (that is, without cargo), and 

 usually do not record the presence of ballast water at all when vessels 

 are "with ballast" (that is, with cargo). We refer to vessels in 

 ballast, as reported in governfflent records, as having acknowledged 

 ballast ; vessels with ballast have unacknowledged ballast . Cryptic 

 ballast Is unacknowledged ballast, unpunpable ballast, reported "no 

 ballast on board" when water is present, and ballast water in vessels 

 not recorded by published government records, such as military vessels. 

 Virtually all vessels ever sampled in D.S., Canadian and Australia 

 studies have been found to contain living organisms. There is now no 

 question that ballast water provides a viable in-transit habitat for a 

 wide variety of freshwater, brackish water, and marine organisms. 

 The potential diversity of "ballastable biota" is often not fully 

 appreciated. Virtually all aquatic organisms that can occur in the 

 water, or be stirred up from bottom sediments, or dislodged off harbor 

 pilings, can be ballasted Into a vessel. Bacteria and viruses also occur 

 in ballast tanks. 



The release of species into the environment during deballastlng leads to 

 differential survival of the species involved. The greater the 

 temperature differences between donor (source) and receiver (target) 

 regions the greater the probability of high mortalities. Thus most 

 organisms from tropical ports will not survive or reproduce in colder 

 temperate or boreal ports, and vice-versa. Exceptions occur where 

 tropical and subtropical species transported to harbors establish 

 reproducing populations in power plant thermal effluents, a phenomenon 



