Water quality should be considered 

 when choosing construction materials. 

 Areas with poor water quality will gen- 

 erally not support populations of grib- 

 bles or borers. If materials that are 

 not resistant to their attack are utilized 

 and water quality is significantly im- 

 proved, there may be problems with 

 premature structural failure. 



Expected Life Span 



Pilings of wood, steel, or concrete 

 will generally have a life expectancy of 

 30 yr or more if they are treated. The 

 environmental factors of an area greatly 

 affect deterioration rates. Conditions 

 of high salinity and high temperature, 

 along with the boring organisms, will 

 likely increase the deterioration process 

 to some degree. 



Plans for removing the piling and 

 other support structures after their ef- 

 fective life span should be submitted 

 when structure is proposed for con- 

 struction. There are severe navigational 

 problems in many areas of the United 

 States, such as in New York Harbor due 

 to the chronic decay and drifting away 

 of pieces of old support structures. 

 Piles or portions of piles remaining just 

 below the water level also present navi- 

 gational hazards. 



Summary of Physical and Biological 

 Impacts 



Construction effects. Construction 

 causes increased turbidity and sedimen- 

 tation which, depending on severity, 

 may reduce primary productivity, inter- 

 fere with respiration of fish, alter the 

 suitability of spawning areas, reduce 

 bottom habitat diversity, and smother 

 benthic organisms(Carstea et al. 1975b). 

 Resuspended bottom sediments may re- 

 lease toxic substances. Noise and vibra- 

 tion, along with turbidity, may tempo- 

 rarily drive fish or invertebrates from 

 the area or cause behavioral modifica- 

 tions. However, in some instances fish- 

 es have been attracted to construction 

 sites due to the suspension of benthic 

 organisms. 



Chronic effects. Docks and piers 

 can cause navigational problems and in- 

 terfere with public use of the water. 



Conflicts may arise concerning adjacent 

 land uses and area aesthetics. In areas 

 where longshore currents, tides, and lit- 

 toral transport are influential, float- 

 ing piers can alter beach sand movement 

 patterns (Coastal Plains Center for 

 Marine Development Service 1973). 



Shading from pile-supported struc- 

 tures may modify the water temperature 

 and wetland habitat. Depending on the 

 amount of shading, there may be a reduc- 

 tion or absence of alqae and grasses 

 under piers (Gifford 1977). But it 

 should also be noted that piling and 

 piers offer substrate for algae growth 

 in some areas where algae did not for- 

 merly grow because the bottom was below 

 the photic zone or presented unstable 

 sediment conditions. White (1975) indi- 

 cated that single residential piers in 

 fresh water are not likely to cause a 

 significant reduction in phytoplankton 

 production. 



Increased use of the area causes 

 related impacts. Boat exhaust and do- 

 mestic emissions can decrease water 

 quality (Carstea et al. 1975b). Impacts 

 may also be caused by increased fishing 

 and litter disposal (Gifford 1977). 



Unless treated, the pilings and 

 other structures provide suitable sub- 

 strate for algae and new attachment sur- 

 faces for invertebrates. These struc- 

 tures also provide cover and feeding 

 sites for fishes and may be used by var- 

 ious birds for nesting or perching 

 (Carstea et al. 1976). Sessile organisms 

 on the exposed surfaces of a piling or 

 other structure as well as the presence 

 of the structure can attract motile or- 

 ganisms, such as fishes, which feed upon 

 the organisms or use the structure for 

 shelter. Such areas generally offer very 

 good fishing. Piles offer resting places 

 and feeding observation posts for coast- 

 al or marine birds, such as pelicans, 

 kingfishers, herons, egrets, and cormo- 

 rants (Carstea et al. 1976). The use of 

 piles and piers by gulls seems to be a 

 universal phenomenon. Channel markers 

 are frequently used as nesting platforms 

 by os prey. 



Cumulative effects. As the number 

 of pile supported structures increase in 

 a given area, the impacts on that area 



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