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mia9

Dataset card Data Studio Files
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C1
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8 clusters
126
129
103
102
101
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- Manatee-Barnes Sound (MBS): includes stations 1, 2, 3 and 4. For detailed
calculation in the box-model, Manatee and Barnes sound samples were
separated as individual clusters.
- Card Sound (CS): includes stations 121 and 135
- South Central Inshore (SCI): includes stations 101, 102 and 103
- South Central Mid-Bay (SCM): Includes stations 110, 112 and 123
- South Central Outer-Bay (SCO): includes stations 104, 108, 109, 111, 112, 113,
116 and 124
- North Central Inshore (NCI): includes stations 127 and 128
- North Central Outer-Bay (NCO): includes stations 126 and 129
- Southern North Bay (SNB): includes stations 130, 131 and 132
- Northern North Bay (NNB): includes stations 133 and 134
Figure 3.4: Final biogeochemical segmentation of Biscayne Bay waters. NCI=North-Central
Inshore; NCO=North Central Outer bay; SCI=South Central Inshore; SCM=South Central Mid
bay; SCO=South Central Outer bay; CS= Card Sound MBS=Manatee-Barnes Sound.
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The subdivision of Biscayne Bay into biogeochemical water classes seems to follow
geomorphological characteristics and patterns defined by physical properties of the
water masses, such as: water depth (Fig 3.5.a; Harlem et al 2009); flood current
velocity (Fig 3.5b; Wang et al 2003); bay bottom type (Fig 3.5c; FWRI 1992); benthic
communities (Fig 3.5d; Roessler et al. 1973; Thorhaug 1976); salinity (Fig 3.5e; Gaiser
et al. 2006); and sedimentary regimes (Fig 3.5f; Wanless, 1984)
Figure 3.5: Correspondence of previous spatial classifications of Biscayne Bay with the
segmentation obtained in this study (colored dots). (a) Bathymetry (Harlem et al 2009);
(b) Flood Current velocity (Wang et al 2003); (c) Bay bottom type (FWRI 1992); (d)
Benthic communities (Roessler et al. 1973; Thorhaug 1976); (e) Salinity (Gaiser et al.
2006); (f) Sedimentary regimes (Wanless, 1984)
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CLUSTERS CHARACTERISTICS
The following statistics were calculated from the SPOR dataset, spanning from
June 1996 to Sept 2007
Freshwater Flow
Net freshwater contributions to each segment in Central and South Biscayne Bay
were calculated for the box-model as the sum of Canal flow + Precipitation +
Groundwater flow + Overland flow – Evaporation for the period Sep 1993-June 2007.
Seasonal freshwater flows (Fig 3.6) display a marked seasonality with very low to
negative contributions from November to May, a sudden and highly variable flow in
June, and peak values in September. Median flows into SCI, although very low in
January-May, are always positive. There are four month with negative net flows in NCI,
five in MBS and CS, and seven in the more offshore segments (NCO, SCM and SCO).
In general, canal discharge to Biscayne Bay south of Rickenbacker Causeway is the
largest contributor to the freshwater budget with 66 million cubic meters per month
(Mm3
/m) or 44% of the total flow, while rain, groundwater and overland flow supply 61
(40%), 15 (10%) and 8 (6%) Mm3 per month, respectively. Average monthly loss due to
evapotranspiration is 79 MMm3, or 53% of the total input (Fig 2.7). Hence, nutrient
loads are basically a function of canal flows and precipitation but residence time and
evapotranspiration would modulate the final effects of these loads. Individual nutrient
loads brought about by these different contributions and the exchange with oceanic
waters determines the final concentration of nutrients within each bay segment
(Appendix 1).
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Figure 3.6: Estimated net freshwater contribution in Mm3/month to Biscayne Bay segments
(Net= Canal + precipitation + groundwater + overland - evaporation). North Biscayne Bay was
not included in the box-model effort.
Salinity
Salinity increases eastwards from shoreline (SCI) to offshore (SCO). The
highest mean and median salinities occur in SCO (35.8 and 36.1 PSU), where most
exchange with oceanic waters takes place, while maintaining its seasonality with little
change along the year (Fig 3.7). Nevertheless, maximum salinity events do not occur in
SCO but closer to shore, in SCI (44.1 PSU) perhaps responding to high evaporation of
shallower water masses. Salinity has reached hypersalinity levels (>40 PSU) in all
clusters during the POR, while median and mean values are similar at each cluster (Fig
3.7). The lowest minima occur also in MBS and SCI (3 and 6 and PSU respectively),
where the standard deviations are the highest (6 PSU), coinciding with previous
observations that sample sites along the shoreline exhibit the highest and the lowest
salinity values and the greatest variation (Serafy et al. 1997; Bellmund et al. 2009). BNP
data shows the occurrence of low salinity events in surface waters away from shore at
the middle of the Bay in November 2004, April 2005, November 2006 and January
2007. These fresher water bodies surrounded by saltier masses have been reported as
caused by groundwater springs (Bellmund et al. 2009) seeping through the bay floor.
Events of salinity inversion appear in FIU dataset but differences are always less than 1
PSU, except in a couple of events
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