View Full Version : Nutrients in the Biscayne Bay of Miami

10-27-2012, 12:18 PM
http://algaescrubber.net/Nutrients in the Biscayne Bay of Miami - Chapter 5 (http://algaescrubber.net/Nutrients in the Biscayne Bay of Miami - chapter 5 - unknown.pdf)

Originally found here:

Note1: The author of this study is unknown; this is just Chapter 5 of the study

Note2: Halimeda and Penicillus have roots; Drift algae does not.

This is a good overall study to learn about how different levels of nutrients affect algae. It's not too complex because it is just a thesis (not a research paper), and does not get into nucleotides, tracers, sequences, or math. Of interest:

Figure 8

Figure 15 ("C" is control)

Comments starting from PDF page 59 (text page 194)......

"the macroalgal community can respond rapidly and sensitively with changing species composition at lower nutrient levels than are typically measured in water samples in nutrient-poor tropical regions (Fong et al. 1994a; McCook 1999). Thus, traditional methods of monitoring water-column nutrients to predict changes in algal community structure may not be warranted (Fong et al. 1994a, 2001), as there is usually little correlation between water-column N and P and either productivity or abundance of primary producers (McCook 1999; Fong et al. 2001)."

"Monitoring the concentration of nutrients within the tissue of macroalgae may be a more useful integrated indicator of long-term enrichment in the environment (Fong et al. 1994a, 1998, 2001). Further, monitoring of macrophyte tissue nutrients to detect enrichment could occur at less frequent intervals than monitoring of water-column nutrients. In this dissertation I found that algae from canal-influenced sites had higher tissue N:P elemental ratios, indicative of higher N-loadings, than the same species from sites that were not impacted by elevated nutrients."

"Rapid cycling of nutrients within the drift [algal] mats may be an important mechanism by which high standing crops can be maintained, even when external concentrations may appear to be limiting."

"nutrient availability based on water-column N and P-concentrations may be poor indicators of limitation, because storage by macroalgae introduces time lags between high water-column concentrations and algal growth. Macroalgae can take up so much N, that water quality seems high even under high N-loading [high N-flux]"

"Water-column nutrients (NO3- and NH4+) are elevated at canal-influenced sites compared to sheet-flow and oceanic sites. Growth and photosynthesis of the three functional groups [Halimeda, Penicillus; Drift] were stimulated by the addition of N, but not P, in experimental microcosms. Analyses of tissue nutrients indicated P is the limiting nutrient. Tissue nutrient contents ranged from 1-4% N, and 0.01-0.2% P, by dry weight, yielding N:P elemental ratios ranging from 12:1-250:1. Growth and photosynthesis were influenced by seasonal light and temperature effects > salinity effects > nutrient addition. The chemical and physical effects of canal discharges on macroalgal physiology appear to be complex, and may require further investigation. Macroalgae play important roles in energy transfer and nutrient recycling in coastal and estuarine areas that have complex seaweed communities."

10-27-2012, 02:31 PM
Cheers SM - a good read.

10-30-2012, 03:31 PM
Note - increasing nitrate levels do induce increased nitrate uptake, but increased phos does not tend to increase phosphate uptake. That's how I read it anyhow.

10-30-2012, 05:22 PM
In this one study, adding N increased growth, which is a separate issue from removing N from the water. When it says P is limiting, it means the algae still grows, but does so with a lower percentage of P in the tissue (i.e., the N:P ratio will be higher). P is usually taken up and stored, however, very fast by the internal polyphosphates. This is how ephemeral algae survive.

For a nutrient to be so low as to actually prevent growth, it's called "critical concentration".