Role of elevated organic carbon levels and microbial activity in coral mortality

Role of elevated organic carbon levels and microbial activity in coral mortality

David I. Kline, Neilan M. Kuntz, Mya Breitbart, Nancy Knowlton, Forest Rohwer

Marine Ecology Progress Series, Vol. 314 (May 22 2006), pp. 119-125

Stable URL:

PDF available

Here we experimentally show that routinely measured components of water quality (nitrate, phosphate, ammonia) do not cause substantial coral mortality. In contrast, dissolved organic carbon (DOC), which is rarely measured on reefs, does.

‘Nuff said!

But the whole article is available, so as usual – click through and read it!

Effects of herbivory, nutrient levels, and introduced algae on the distribution and abundance of the invasive macroalga Dictyosphaeria cavernosa in Kaneohe Bay, Hawaii

Effects of herbivory, nutrient levels, and introduced algae on the distribution and abundance of the invasive macroalga Dictyosphaeria cavernosa in Kaneohe Bay, Hawaii

Coral Reefs (2001) 19: 343-357

DOI 10.1007/s003380000123

PDF available.

Bubble algae!  The less-fun variant in the Family.  (Valonia is not so bad.)

Don’t provide foods to your herbivores that are more desirable.   Pellet food was the “worst”….mysis were better and more herbivores ate bubble algae when that was the tank’s food.

Aerosol dispersal of the fish pathogen, Amyloodinium ocellatum

Aerosol dispersal of the fish pathogen, Amyloodinium ocellatum

Aquaculture, Volume 257, Issues 1–4, 30 June 2006, Pages 118-123

Ashley Roberts-Thomson, Andrew Barnes, D. Stewart Fielder, Robert J.G. Lester, Robert D. Adlard

PDF Available


They performed three sets of tests to see how “suseceptible” a tank or pond could be when placed “close” to infected tanks:

  • The first set was more or less a typical indoor home aquarium setup.
  • The second set was an indoor setup, but force-aerosolized the infected water.
  • The third set was more typical of a pond system and simulated outdoor windy conditions and also force-aerosolized the infected water.

This is a table I prepared to show the organization of their trials into three sets of experiments:

velvet table.png

The goal of their experiments was to prove whether Amyloodinium can “ride” a water droplet to a foreign body of water and arrive intact enough to infect fish.

They did this successfully, and indeed Amyloodinium can “ride” water droplets.  But that might not be the most interesting part to us in the reefing community.

Here are some charts I made which depict the reported results for the three sets of experiments:

velvet charts.png

The first thing that jumps out at me – from the first chart – is that airstones running in an open tank like a stereotypical home setup are totally unable to spread dinospores.

As it turns out, dinospores are relatively big and subject to hypersalinity and dehydration while in transit.   It took a lot more than bubbles in a fish tank to achieve transmission – they need a lot of help to get anywhere successfully!


The second and third chart demonstrate the successful conditions.

Without strong wind, dinospores were only infective out to a maximum of 17 inches from the source tank.

Forced-arosolization was implemented in these two experiments by spraying 2 liters of dinospore-infected water into the air through a hand-pumped sprayer somewhat like the one depicted to the left, fitted with a misting nozzle.

The Ecological Role of Water-Column Microbes in the Sea

The Ecological Role of Water-Column Microbes in the Sea
Marine Ecology Progress Series, January 1983
DOI: 10.3354/meps010257

PDF Available


This article gives some insight into the ecology we are missing when we try to control algae blooms with carbon dosing.

It’s not even close to a simple bacteria vs algae contest, or bacteria-to-skimmer export that gets reported in hobby literature.

A few quotes:

There is evidence that bacteria show kinesis [movement] in a field 10 to 100 µm from algal cells, close enough to take advantage of DOM (Azam, in press). Under laboratory conditions in natural sea- water, bacteria were observed to remain at distances of the order of 10 pm from algal cells, possibly being repelled by antibiotics produced by healthy algae. They attach mainly to moribund algae.

[…]it follows that the supply of either carbon for energy, or other nutrients may limit bacterial growth.  However, in phytoplankton blooms DOM is often produced, and bacteria with their large surface:volume ratio are adapted to scavenging nutrients from the water at very low concentrations.  The difficulties experienced in quantifying the release of DOM by algae are almost certainly due to its rapid uptake by bacteria.  The same argument applies to nutrient cycling.  If bacteria are so well adapted to
scavenging DOM and nutrients at low concentrations, what limits their population size to the biomass levels given in Table I ? Fenchel (1982a,b, c, d, in press) has shown that heterotrophic microflagellates in the size range 3 to 10 pm are effective bacteriovores in the sea, capable of filtering 12 to 67 % of the water column per day (see also Sorokin, 1979; Sieburth, 1982).These are principally choanoflagellates and colourless chry- somonads[…]


Total replacement of fish oil by soybean or linseed oil with a return to fish oil in Turbot

Total replacement of fish oil by soybean or linseed oil with a return to fish oil in turbot (Psetta maxima): 1. Growth performance, flesh fatty acid profile, and lipid metabolism
Original research article
Aquaculture, Volume 217, Issues 1–4, 17 March 2003, Pages 465-482
C Regost, J Arzel, J Robin, G Rosenlund, S.J Kaushik
PDF Available

Total replacement of fish oil by soybean or linseed oil with a return to fish oil in Turbot (Psetta maxima): 2. Flesh quality properties
Original research article
Aquaculture, Volume 220, Issues 1–4, 14 April 2003, Pages 737-747
C. Regost, J. Arzel, M. Cardinal, G. Rosenlund, S.J. Kaushik

In summary, it’s possible to replace at least some of a marine fish’s diet with high quality, specifically selected vegetable oils, but it’s not a perfect replacement in every way.

For example, growth seems unaffected, but flavor, odor and other important factors are affected.

Some, but not all, affected factors can be reformed by a “finishing diet” consisting of normal food containing fish oil.

Adaptive Ecology, Growth Strategies and the Global Bloom Expansion of Dinoflagellates

Adaptive Ecology, Growth Strategies and the Global Bloom Expansion of Dinoflagellates

Theodore J. Smayda

Journal of Oceanography, Vol. 58, pp. 281 to 294, 2002

DOI: 10.1023/A:1015861725470

First, I must say that Dr. Smayda (d.2017) was apparently “The Man” when it came to study of harmful algae blooms.  I wish I had bumped into him sooner.

Read anything you can find by him.  Read anything that cites his work.

This work is a review article….click through and read the whole thing!!

Dinoflagellates behave as annual species, bloom soloists, are ecophysiologically diverse and habitat specialists, whereas diatoms behave as peren- nial species, guild members and are habitat cosmopolites. Diatoms have a relatively uniform bloom strategy based on species-rich pools and exhibit limited habitat spe- cialization. Dinoflagellates have multiple life-form strategies consistent with their diverse habitat specializations, but rely on impoverished bloom species pools.

Diatoms and flagellates, for example, generally have similar nutrient requirements (excluding the need for silica), but diatoms, when nutrient-limited, seek to alleviate limitation through a sink-strategy, while flagellates use a swim-strategy (Smayda, 1997a).

Diatom blooms (independent of species composition) have five major features: coastal (including upwelling systems) diatom blooms are annually recurrent, predictable, prolonged, of high species diversity, and a species succession occurs (Guillard and Kilham, 1977; Smayda, 1980). Dinoflagellate blooms, in contrast, usually are unpredictable, ephemeral, of low species diversity, and exhibit a rudimentary species succession, if any.

That’s only the tip of the iceberg….click and read!!!

The toxic benthic dinoflagellates of the genus Ostreopsis in temperate areas: a review

The toxic benthic dinoflagellates of the genus Ostreopsis in temperate areas: a review

Stefano Accoroni, Cecilia Totti

Advances in Oceanography and Limnology, 2016; 7(1): 1-15

DOI: 10.4081/aiol.2016.5591

Key Points:

  • Correct ID of Ostreopsis species in the field (distinguishing between them) is “highly problematic” requiring a comparison of precise anatomical measurements and experience comparing strains from different regions.  Even genetic ID has been complicated.  They are now referring to some Ostreopsis as species-complexes and clades.
  • Either P- or N-depletion has been shown to lower Ostreopsis ovata toxicity.  (Strain, growth phase and salinity all figure it too.)
  • Turbulence affects growth rate/cell-size.
  • Cell counts were consistently lower in exposed sites vs sheltered ones.
  • Dino’s are easy to dislodge, which is why they show a preference for calm areas
  • Turbulence is most effective against them at the peak population levels when they are mat-forming.
  • While it appears there is a general preference for higher temperatures during the peak bloom (77ºF+) they tend to range widely and some strains appear to have multiple optimal ranges.
  • N:P around the Redfield ratio and temperatures of at least 77ºF seems necessary to allow cell proliferation.
  • Temperatures to stop a bloom were much lower, however – around or under 60ºF.
  • Blooms appear to be initiated under low-N/low-P conditions and then spike with a flush of nutrients.
  • It’s also suggested that Ostreopsis toxins might be intended for survival under low-N/low-P conditions while waiting for conditions to become ideal.  (Which seems to be an elevation in temperature along with a spike in nutrients.)
  • At least one strain of Ostreopsis showed a very strong demand for P in depletion tests, which was remarkable among dinoflagellates.
  • It’s suggested that Ostreopsis may share the habit known of other dinoflagellates for resorting bacterivory/mixotrophy under low-P/low-nutrient conditions.
  • Most Ostreopsis species exhibited lowered growth rates at light intensities around 250 PAR and higher….sometimes only slightly lowered, sometimes significantly.
  • Higher light levels may also be related to mucus formation (for photodamage protection) and settling from their planktonic stage.
  • However, being motile, they are also capable of migrating from brighter to shadier areas.
  • Although recorded in the wild on a variety of substrates, there are many reports that they prefer to be epiphytic on macroalgae, which as an environment is known to have low light availability.
  • Interestingly, living substrates like macroalgae support the lowest cell densities of all sampled substrates.
  • All investigated seaweed types exhibited a negative effect on Ostreopsis counts: brown, red and green algae.  The brown algae Dictyota dichotoma had the strongest effect….a red algae the weakest.