IV. RESULTS AND DISCUSSION 
1. Hydrographic Conditions 
Water sample analysis for temperature, salinity and dissolved oxygen 
(Tables 2 and 3) reflected expected hydrographic patterns for this area. 
Temperature differences between surface and bottom waters were always 
similar with a normal difference of less than 0.3°C. Lowest temperatures 
(5.8° - 6.0°C) were observed during the winter and highest temperatures 
(26.5° - 30.3°C) occurred during summer. Salinity measurements were 
always high (34.5 - 36.1 °/oo) during the four-year study period since 
Murrells Inlet receives no significant fresh water input. No salinity 
data are presented for 1982 due to a faulty meter, but refractometer 
estimates indicated that salinities were in the same range that year. 
Dissolved oxygen values were generally high and near saturation values 
since the shallow waters in this area are well mixed by wave action. 
Finally, no consistent differences were noted between stations on the 
north versus south jetty. 
Water clarity varied considerably during the study, being mostly 
dependent on tidal stage and wave action. Clarity increased during 
flood tides and was often greatest on the exposed side of the north 
jetty. The turbid waters from the inlet decreased water clarity at 
channel (protected) stations on both jetties, especially during ebb tides. 
The very shallow waters on the exposed side of the south jetty were also 
generally more turbid than on the deeper exposed side of the north jetty. 
2. Jetty Community Development 
Data obtained from north and south jetty sampling indicate that a 
diverse assemblage of biota colonized the rocks during the first four 
years after construction. At least 25 species of algae, 195 species of 
macroinvertebrates and 34 species of fish were observed or collected on 
the jetties, with distinct temporal changes noted each year in the 
community composition. Vertical gradients in the distribution of fauna 
and flora on the rocks were also evident, particularly in the intertidal 
zone. The following sections provide details’on the colonization, 
community development, and distribution patterns observed on both jetties. 
a. Sessile Biota. 
Percent cover estimates for the sessile macroinvertebrates and 
algal species are listed in Appendices A and B for the four north jetty 
study sites, and Appendices C and D for the four south jetty sites. 
Appendix E provides estimates of total biota cover on the rocks using the 
two census techniques. The line-transect census (Appendices A and C) 
generally provided more detailed information on community composition 
at the different levels because taxonomic identifications were often more 
refined than possible in the analysis of photographed quadrats (Appendices 
B and D). However, the latter technique did provide useful supplemental 
information, particularly for the larger dominant biota which could be 
easily identified. 
16 
