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CHAPTER 5 - BIOLOGICAL CHARACTERISTICS<br />

5.1 Benthos<br />

5.1.1 Descriptive<br />

The <strong>Weeki</strong> <strong>Wachee</strong> <strong>and</strong> Mud <strong>River</strong> benthic communities were sampled in 1984-85<br />

(Culter 1986) <strong>and</strong> again during 2005 (Janicki Environmental 2006). In the 1986 study,<br />

Culter sampled using a diver operated box corer (10 replicates per site) at four stations<br />

from 5.8 km 15 offshore up to Rkm 2.4.<br />

In the most recent survey, round h<strong>and</strong> core samplers were used to collect infauna along<br />

fifteen transects in the <strong>Weeki</strong> <strong>Wachee</strong> <strong>and</strong> ten transects in the Mud <strong>River</strong>. Sweep nets<br />

were used to sample the epifauna. The polychaete Laeonereis culveri <strong>and</strong> the<br />

amphipod Gammarus mucronatus were among the dominant epifauna taxa. The<br />

dominant epifaunal taxa consisted of amphipods (Gammarus mucronatus <strong>and</strong><br />

Gr<strong>and</strong>idierella bonnieroides) in both the <strong>Weeki</strong> <strong>and</strong> Mud <strong>River</strong>s. The asellote isopod<br />

Uronmunna reynoldsi was also dominant in the <strong>Weeki</strong> <strong>Wachee</strong> but not the Mud <strong>River</strong>.<br />

In contrast, the tanaid Hareria rapax <strong>and</strong> the mysid Taphromysis bowmani were among<br />

the top ten dominants in the Mud <strong>River</strong> but were not ranked in the <strong>Weeki</strong> <strong>Wachee</strong>.<br />

5.1.2 Relation to inflow<br />

Quantitative relationships with inflow were not developed with the benthic results,<br />

although salinity was evaluated along with other physical-chemical parameters. Data<br />

from the <strong>Weeki</strong> <strong>Wachee</strong>, Mud <strong>and</strong> Chassahowitzka <strong>River</strong>s were pooled <strong>and</strong> several<br />

summary statistics developed. Table 5-1 presents the results for response to salinity,<br />

while Table 5-2 provides response to salinity, pH, temperature, dissolved oxygen, depth<br />

<strong>and</strong> sediment size.<br />

Table 5-1<br />

Benthos Response to Salinity – <strong>Weeki</strong> <strong>Wachee</strong>, Mud <strong>and</strong> Chassahowitzka <strong>River</strong>s<br />

Metric r 2 adj. regression<br />

Number of Taxa - log 10 (taxa +1) 0.62 = 0.66 + 0.114 * Salinity - 0.007* Salinity^2<br />

Abundance - log 10 (N+1/m2) 0.40 = 3.42 + 0.197 * Salinity - 0.012* Salinity^2<br />

Shannon-Wiener Diversity (H') 0.55 = 1.41 + 0.326 * Salinity - 0.012* Salinity^2<br />

WW_Bentho_Tabs.xls<br />

15 Subsequent cluster analysis by Janicki (2006) indicated that the offshore sampling results represent a<br />

distinct group of organisms.<br />

____________________________________________________________________________________________<br />

Proposed <strong>Minimum</strong> <strong>Flows</strong> <strong>and</strong> Levels for <strong>Weeki</strong> <strong>Wachee</strong> <strong>River</strong> Page 71 of 164<br />

Biological Characteristics

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