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Calcareous Algae 420 0-2.83 0.30 ± 0.46 109.407 29 0.000
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Table 8. Seagrass cover-densities (#/m2
) mean, standard deviation, minimum and
maximum by site (1-30) and location type within the Port of Miami basin (refer to Figure
3).
Seagrass CoverDensity Site Location Mean
Std.
Deviation N Hi/Low
Syringodium 17 East Coast Grass patch 3.32 0.85 14 max
5
Channel in center of
basin 0.10 0.36 14 min
25 South of Port Islands 0.10 0.23 14 min
Thalassia 7
Virginia Key Protected
Area Grass patch 3.13 1.85 14 max
29 South of Port Islands 0.02 0.09 14 min
Halodule 15
Virginia Key Protected
Area Grass patch 1.83 1.79 14 max
19
Channel in center of
basin 0.00 0.00 14 min
3.2 Environmental and Physical Conditions in Port of Miami, 2005-2011
Water depth, sediment depth, turbidity, surface and bottom temperature and
salinity measurements were taken at each site within the POM basin. Observed water
depths ranged from 44 cm to 605 cm over the basin, averaging 213.14 ± 79 cm (Figure
12C). Sediment texture was measured at 2147 of the 2159 quads sampled and 89.8% of
the quadrats contained a combination of mud and/or sand substrate. The sediment depth
averaged about 130.28 ± 84.1 cm and ranging from 4 cm to over 300 cm in the basin
(Figure 12D). Turbidities were generally low over all fourteen collections, averaging
2.58 ± 1.76 NTU (Figure 12E).
Average water column values could not be used for salinity because an
independent samples t-test determined there was a significant difference between the
surface and bottom measurements (t(420) = -2.815, p < 0.001). Temperature
measurements did not show a significant difference within the water column (t(420) = -
0.368, p = 0.923), but due to the relationship between temperature and salinity, both
surface and bottom measurements were used instead of the averages for temperature and
salinity. Surface salinity was lower overall and ranged between 12.60 and 39.10‰
(33.07 ± 3.46‰), while bottom salinity ranged between 25.60 and 38.40‰ (33.65 ±
2.53‰) (Figure 12B). Surface temperature was slightly lower overall and ranged
43
between 20.80 and 32.50 °C (27.41 ± 2.64 °C), while bottom temperature ranged between
21.90 and 32.50 °C (27.48 ± 2.86 °C) (Figure 12A). Salinity and Temperature patterns
were typical of South Florida inshore water (see Appendix 3).
The combined General Linear Model for annual and seasonal effect (year*season)
on environmental and physical measurements indicated variables such as water depth,
turbidity, salinity, and temperature are significantly different over time, but not sediment
depth (see Table 9). A significant seasonal effect was seen with water depth, salinity,
temperature, and turbidity (p < 0.05) (see Table 9 and Figures 13A-E). The fall (wet)
season measured higher water depths (Figure 13C) and temperatures (Figure 13A), while
the spring season had higher salinity measurements (Figure 13B). Differences in water
depth between seasons can be attributed to tide level and proximity to the deeper
channels within the basin. In both the spring and fall collections, bottom salinity was
greater than surface salinity (Figure 13B).
There was a significant annual effect on all environmental and physical variables
over the sample period (p < 0.01) (see Table 9). Annual differences were revealed
through the Tukey post-hoc tests (see Figures 12A-E). Between sample years 2006 and
2007, the most significant differences in salinity were measured (Figure 12B). 2006
measured the lowest and 2007 the highest salinities over the study period. The most
significant changes in temperature were observed between 2009 and 2011, with 2010
measuring the lowest and 2011 measuring the highest temperatures over the study period
(Figure 12A). The water depth and sediment depth measurements varied between most
sample years. The most significant variation in water depths were measured between
2007 and 2008 (Figure 12C). Sediment depth measurements differed most significantly
between the 2007-2008 and 2010-2011 sampling years (Figure 12D). From 2008 to 2009
the most significant decrease in turbidity was measured (Figure 12E).
44
Table 9. Summary of a General Linear Model of FIAN environmental and physical variables by
Year*Season. Temperature (°C), salinity (‰), turbidity (NTU), sediment depth (cm), and water
depth (cm).
General Linear Model - Tests of Between-Subjects Effects - Year * Season
Source
Type III
Sum of
Squares df
Mean
Square F Sig.
Partial
Eta
Squared
Noncent.
Parameter
Observed
Powerh
Year Water Depth 120399.965 6 20066.661 3.460 .002 .049 20.759 .945
Sediment Depth 298846.221 6 49807.704 7.766 .000 .103 46.597 1.000
Turbidity 411.790 6 68.632 35.600 .000 .346 213.603 1.000
Surface Temperature 532.337 6 88.723 149.625 .000 .690 897.748 1.000
Bottom Temperature 500.542 6 83.424 300.604 .000 .817 1803.622 1.000
Surface Salinity 425.324 6 70.887 12.342 .000 .155 74.055 1.000
Bottom Salinity 253.374 6 42.229 15.073 .000 .183 90.436 1.000
Season Water Depth 43886.735 1 43886.735 7.567 .006 .018 7.567 .784
Sediment Depth 8557.452 1 8557.452 1.334 .249 .003 1.334 .211
Turbidity 9.016 1 9.016 4.677 .031 .011 4.677 .578
Surface Temperature 1708.849 1 1708.849 2881.850 .000 .877 2881.850 1.000
Bottom Temperature 1891.629 1 1891.629 6816.169 .000 .944 6816.169 1.000
Surface Salinity 1566.779 1 1566.779 272.798 .000 .403 272.798 1.000
Bottom Salinity 936.840 1 936.840 334.384 .000 .453 334.384 1.000