Trophic dynamics of scleractinian corals: stable isotope evidence

Trophic dynamics of scleractinian corals: stable isotope evidence

Pascale TremblayJean François MaguerRenaud GroverChristine Ferrier-Pagès

Bacterivory in algae: A survival strategy during nutrient limitation

Bacterivory in algae: A survival strategy during nutrient limitation

Association for the Sciences of Limnology and Oceanography
http://aslo.org/lo/toc/vol_38/issue_2/

Table of Contents, Vol. 38 (2), 1993
NYGAARD, KARI, AND AUGUST TOBIESEN
“Bacterivory in algae: A survival strategy during nutrient limitation” p.273-279

Bacteria have a high P content even when phosphate is limited (Andersen et al. 1986), although their P content can be reduced when they are drastically starved (Tezuka 1990). Bacteria are therefore a potential source of P when obligate phototrophic algal flagellates are subjected to P limitation, because bacteria are more efficient at sequestering P under these conditions (Bratbak and Thingstad 198 5).

Phosphate deficiency alone may be insufficient for the success of bacterivorous algae because their growth requires that other environmental factors are also favorable.

Bacteria have been shown to out-compete algal flagellates in phosphate-limited chemostats at low dilution rates (Currie and Kalff 1984; Bratbak and Thingstad 1985).

Our results suggest that algae able to graze and use P compounds in the bacteria will have a compensatory mechanism to overcome their competitive disadvantage.

If you want to avoid toxic algae in your tank, avoid this condition!

Function of Funnel-Shaped Coral Growth in a High-Sedimentation Environment

Function of Funnel-Shaped Coral Growth in a High-Sedimentation Environment

Bernhard Riegl, Carlton Heine, and George M. Branch. 1996. Function of Funnel-Shaped Coral Growth in a High-Sedimentation Environment .Marine Ecology Progress Series : 87 -93.
http://nsuworks.nova.edu/occ_facarticles/336.

“Current speeds between 30 and 90 cm s-1 were enough to clean the funnels of 3 experimental grain sizes (coarse, fine, medium sand).”

High phosphate uptake requirements of the scleractinian coral Stylophora pistillata

High phosphate uptake requirements of the scleractinian coral Stylophora pistillata

Claire GodinotRenaud GroverDenis AllemandChristine Ferrier-Pagès

Ratio of Energy and Nutrient Fluxes Regulates Symbiosis between Zooxanthellae and Corals

Ratio of Energy and Nutrient Fluxes Regulates Symbiosis between Zooxanthellae and Corals

Dubinsky Z, Jokiel PL. 1994. Ratio of energy and nutrient fluxes regulates symbiosis between zooxanthellae and corals. Pac Sci 48(3): 313-324.

http://hdl.handle.net/10125/2241

Full article available.

(See also: https://pacificscience.wordpress.com/open-access-v1-v54/pacific-science-48-1994/)

[Summarizing] the main interactions and feedback mechanisms connecting light intensity, nutrient level, and feeding in zooxanthellate corals:

  1. Under constant nutrient concentration, light intensity determines the onset of nutrient limitation; as light increases, C : N ratios exceed Redfield ratios.
  2. The availability of other nutrients, mainly nitrogen, determines the fate of photo-assimilated carbon. Under high C: N ratios, most carbon goes into respiration, calcification, and excreted mucus, whereas low C : N ratios favor increases in zooxanthellae density, reduce translocation, and slow down calcification.
  3. Feeding on zooplankton by the coral under low light provides carbon for metabolism. Under high light it supplies both algae and animal with nitrogen.

Nutrient balance is one of the most important, but seemingly lease understood aspects of aquarium keeping.  This statement from the article summarizes it as well as I’ve seen it summarized.  I’ve edited only for clarity.

Also from this article:

Nutrients acquired by predation of the coral on zooplankton are available first to the animal, whereas those absorbed by the zooxanthellae from seawater as inorganic compounds lead first to growth of the algae.

Online Triangle Calculator

triangle_calculator
Triangle Calculator from ostermiller.org

This is a triangle calculator.

Specifically, this is the open source triangle-calculator provided here:

https://ostermiller.org/calc/triangle.html

Since an LED emits light roughly in the shape of a cone, we can use triangle math to predict the amount of area an LED in a particular installation will light up.

After the calculator has any three parts (not only the ones I entered) of the triangle, it will calculate the rest of the parts.

In the calculator pictured, I’ve entered the three values that are depicted in green – the calculator figured out the rest.

For this example, I know:

  • I have 90° lenses
  • I have to cover a 20″+ diameter of surface area

I need to know how high to mount the fixture to get 20″ in diameter of coverage.

Here’s how I filled out the calculator:

  1. Divide the 90º lens by two to get angle 1: 90° / 2 = 45°
  2. The light is perpendicular to the water, so angle 2 is 90°
  3. Divide the diameter by two for the radius you need to cover, for side 120″ / 2 = 10

From this, the calculator tells us (side 2) that the light should be mounted 10″ above the water.

Here’s a simple diagram I created based on some similar calculations:

72x24_1
Light diagram by Matt Carroll. aka TheRealMattCarroll.

Spectrometer

 

This is my Project STAR spectrometer.  It was very inexpensive.

img_3218
The Project STAR spectrometer. Clockwise from the top-left, the long, curved feature is the housing for the graduated scale; next to it is the small light-intake port; at the bottom-edge is the whitish diffraction grating which is just above, or in front of, the eyepiece.

I  use it for examining the color of different lights inside and outside.  (Don’t look directly at the sun through this device – or anything else!)

It works by taking in light via the small opening at the upper-right.

The light bounces off the diffraction grating at the bottom of the photo.

It then spreads out over the graduated scale, which is inside the curved feature at the top of the photo.

I view the scale through the eyepiece that’s at the bottom of the photo.

I don’t get a histogram showing relative wavelength intensity, but it’s really easy to see what wavelengths are strong or weak, or which ones are missing.

I love having this!

 

 

 

 

spectrometer_output
View through the eyepiece of a Project STAR spectrometer. The light is from a 48″ Phillips 6,500K T12 lamp.
spectrometer_light_intakes
The Project STAR spectrometer. Clockwise from the top-left, the long, curved feature is the housing for the graduated scale; next to it is the small light-intake port; at the bottom-edge is the whitish diffraction grating which is just above, or in front of, the eyepiece.
spectrometer_intake_port
The Project STAR spectrometer. Clockwise from the top-left, the long, curved feature is the housing for the graduated scale; next to it is the small light-intake port; at the bottom-edge is the whitish diffraction grating which is just above, or in front of, the eyepiece.
spectrometer_backlight_port
The Project STAR spectrometer. Clockwise from the top-left, the long, curved feature is the housing for the graduated scale; next to it is the small light-intake port; at the bottom-edge is the whitish diffraction grating which is just above, or in front of, the eyepiece.
spectrometer_refguide
The Project STAR spectrometer. Clockwise from the top-left, the long, curved feature is the housing for the graduated scale; next to it is the small light-intake port; at the bottom-edge is the whitish diffraction grating which is just above, or in front of, the eyepiece.