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!

Book: Biology of Stress In Fish – Fish Physiology (Chapter 12 – Stress Management And Welfare)

Book: Biology of Stress In Fish – Fish Physiology (Chapter 12 – Stress Management And Welfare)

Lynne U Sneddon, David C.C. Wolfenden, Jack S Thomson
Biology of Stress in Fish – Fish Physiology, pp.463-539

The Chapter 12 authors have posted their work on Research Gate here:

DOI: 10.1016/B978-0-12-802728-8.00012-6 (Science Direct)

There is not only a lack of familiarity with what constitutes stress and what side-effects stress can have, but there’s even a pretty fair amount of denial of it’s role in health and sickness.  All of that is laid fairly to rest in this book.

For example from this chapter, we can learn:

  • Short term (acute) stress – like being caught in a net – isn’t so bad for a fish.  It’s just a coping mechanism and long term consequences would not be expected.
  • Long term (chronic) stress – like three months in QT with a pack of strange fish – will have a more lasting negative impact on growth, immunity and reproduction.

In spite of how much of the book is online, they don’t allow quoting from any of it from any source I’ve found, so you can read the rest for yourself!

Programmed cell death in protists

Programmed cell death in protists

Marcel Deponte

This is a great review article for us!

In the case of the blooming dinoflagellates, Vardi et al. suggested that by allowing only the best adapted individuals to establish cysts, while eliminating less healthy members of the community at the end of the bloom, programmed cell death might confer a selective advantage to a population during subsequent seasons.

The main part of interest will surely be Table 1 in the document where each protist and it’s programmed cell-death details are indexed.

Microbial Community Management in Aquaculture

Microbial Community Management in Aquaculture

Procedia Food Science, Volume 6, 2016, Pages 37-39
P. Bossier, P. De Schrijver, T. Defoirdt, H.A.D. Ruwandeepika, F. Natrah, J. Ekasari, H. Toi, D. Nhan, N. Tinh, G. Pande, I. Karunasagar, G. Van Stappen

Under a Creative Commons license

The expansion of the aquaculture production is restricted due to the pressure it causes on the environment by the discharge of waste products in the water bodies and by its dependence on fish oil and fishmeal. Aquaculture using bio-floc technology (BFT) offers a solution to both problems.

All biofloc size classes were consumed and utilized by the shrimp, tilapia and mussel. The highest retention of nitrogen in the animal body, however, was consistently originating from the bioflocs larger than 100μm

Survival in the [immunity] challenge tests with shrimp from the biofloc [fed] groups, was also significantly higher compared to the positive control.

Rather than trying to control microbial community composition, microbial activity can be steered. The disruption of quorum sensing, bacterial cell-to-cell communication, has been suggested as an alternative strategy to control infections in aquaculture 5.

Recent studies also indicate that opportunistic aquatic pathogens[…]are also able to sense host clues such as stress hormones.


Impacts of nutrient enrichment on coral reefs: new perspectives and implications for coastal management and reef survival

Impacts of nutrient enrichment on coral reefs: new perspectives and implications for coastal management and reef survival

Current Opinion in Environmental Sustainability, Volume 7, April 2014, Pages 82-93
Cecilia D’Angelo, Jörg Wiedenmann

This article is in the Creative Commons.

This is a really nice review article that touches on many areas that are important to us as reefers.  As a result, it has a GREAT collection of citations that are pretty directly applicable to us and our situation.

A few quotes to whet the appetite – then go read!

We have recently shown that increased nutrient levels might not negatively affect the physiological performance of zooxanthellae as long as all essential nutrients are available at sufficient concentrations to ensure their chemically balanced growth 28.  These results could explain why some reefs and the nutritional status and metabolism of their inhabitants do not always show negative responses to eutrophication [29• ;  30•], at least in the absence of temperature and light stress.

We’ve already been making use of this fact….when you’re done reading this article, check out our post: A Nitrate Dosing Calculator For Better Tank Health (And Better Coral Color!)

Another tidbit from the article:

Most recently, however, we could demonstrate that corals exposed to elevated nitrogen levels were more susceptible to bleaching when exposed to heat and light stress [28]. Interestingly, the detrimental effects observed in these experiments could be attributed to the relative undersupply of phosphorus that resulted from the enhanced demand of the proliferating zooxanthellae population rather than to the elevated nitrogen levels themselves (Figure 1 ;  Figure 2).


We’ve been promoting this information (at least here on the blog) for quite a while now.

Antimicrobial Peptides from Fish

Antimicrobial Peptides from Fish

Jorge A. Masso-Silva and Gill Diamond

Pharmaceuticals 20147(3), 265-310; doi:10.3390/ph7030265

“AMP” = antimicrobial peptide

Piscidins exhibit potent antimicrobial activity against a variety of microorganisms.

They are widely active against bacteria Gram-positive and -negative species…

Piscidins have also been shown to possess anti-fungal activity, anti-parasitic activity, and anti-viral activity.

Piscidins are mainly expressed in gill, skin and intestine, although can be also found in head-kidney and spleen. However, in Atlantic cod piscidin was found to be ubiquitous, being detected in chondrocytes, heart, oocytes, exocrine and endocrine glands, swim bladder, and other tissues.

Like AMP genes from mammals, piscidin genes can be induced by a variety of stimuli, including Gram-positive and -negative bacteria, bacteria cell components like LPS or the bacterial antigen ASAL.

Furthermore, piscidin genes are induced by parasites, viruses,…

Another study demonstrated that high biomass density (i.e., a higher concentration of fish per volume water in an experimental tank) used as an acute stressor component, led to an to up-regulation of dicentracin in gills and skin as well.

Histone-derived AMPs have been identified in a number of fish species, with broad-spectrum activity against both human and fish pathogens, including water molds and a parasitic dinoflagellate. They are expressed and secreted in fish skin, and found in other tissues, including gill, speen and the gut.

Further evidence that they play a role in host defense of the fish comes from studies showing that expression of histone-derived AMP genes are induced under conditions of stress in specific tissues of different fish species.

This is just a sample of quotes that focuses only on piscidins and histidins, where the review article goes on at length with lots more good info.

There really should be no doubt about a healthy fish’s ability to defend itself.

The doubt should be focused on whether, or how much, we limit or support their abilities with stress and nutrition.

A Nitrate Dosing Calculator For Better Tank Health (And Better Coral Color!)

by Stratos

It has become a phenomenon of increasing frequency in the reefing hobby today to have “too clean” of a tank.  Zero nitrates, and sometimes even zero phosphates are found behind more and more tank issues.  Either can be quite problematic for the tank.

With the ever popular “ULNS” systems and all methods of carbon dosing exponentially increasing in usage, nutrient starvation in our glass boxes is almost as common as the opposite.  Pale colors in corals are one of the more common side effects.  But there can be many side effects to a tank’s microbial food web ,aka microbial loop.  (Also see other entries in the Nutrients section of the blog.  –Ed)

Thankfully, there are many ways to increase and maintain nutrients.

Limiting nutrient export (e.g. water changes, reduced skimmer usage, shorter refugium lighting hours, etc) and increasing the rate of nutrients introduced into the system with extra feedings might be the two easiest ways.

However, in some cases, “nutrient dosing” is definitely something of interest – particularly nitrate dosing.

There has been a lot of discussion about the different reagents that could be used – a great one being potassium nitrate (KNO3).  Also known as salt peter.

One great source for KNO3 is a product by Spectracide called Spectracide® Stump Remover Granules.

Initially this registered on my radar from an excellent post on Reef2Reef.

I was intrigued by the idea of being able to add exactly what the system needs.

The instructions on the thread are fairly easy and straightforward:

  • Add 2 tablespoons of the Sump Remover (granules) in a plastic cup of RODI water.
  • Use that to dose approximately one milliliter per ten gallons of aquarium water.
  • Then test and adjust accordingly.

Although this is a very simple approach, I had an uneasy feeling which kept me from slapping a quick dilution together and dumping it in. I wanted to have some additional confidence that it would succeed and perform as expected.  Knowing that I can easily calculate the exact dilution to raise nitrate exactly, I started digging a little further.

My first data was the SDS (Safety Data Sheet) of the Spectracide product.  It states unequivocally that the composition is 100% potassium nitrate. This is a bold statement to make as many SDS like to leave room for impurities – anything up to 99% potassium nitrate would have left the door open for some impurity. 100% purity gives a good comfort in using the product and expecting it to be and perform as predicted.

KNO3 Screen.pngIdeally, for my purposes, a calculator is created to assist with the dosing.

The calculator I created (depicted to the left)  consists of three main parts.

The first part helps with the creation of a stock solution that has a known nitrate content.

The second part helps with determining how much of that stock should be added in a known volume (your tank’s volume) to increase nitrate by how much.

The third section is where specific doses are calculated to address specific deficiencies.

The calculator is assembled as a Google docs sheet here.

Look closer at the KNO3 molecule in the Molecular Properties section of the calculator.

In order to know how much nitrate we will be adding, we need to know what is the ratio of nitrate is to other atoms in the KNO3 molecule by mass. 

That section concludes that the ratio is about .61.  Or in other words, about 61% of the weight of the KNO3 molecule is nitrate.

Solution Properties, the second section of the table, shows that if we create a stock solution of 10 grams of KNO3 in 500 milliliters of RODI water we are going to have a solution that has approximately 12,265 ppm of nitrate.

The third block, Dosing Calculations, shows that if we take 1 milliliter of the stock solution and we dose it into a 30 gallon system, we are going to increase nitrate by 0.1 ppm.

Indeed, following this, I created the depicted solution and dosed 5 milliliters in my 30 gallon tank and after an hour, when I tested, I had 0.5 ppm of nitrate.

It’s worth noting that to help keep the integrity of the calculations, the sheet is shared as “view only”.

You can still make a copy of it on your drive or if you don’t have a Google account you can also download the file to your computer.

In that calculator, there are a couple more things worth mentioning.

First, the other different forms of nitrate available also have calculators built into the Full tab of the spreadsheet – namely sodium nitrate and calcium nitrate each have their own calculator table.

It is fairly straight forward to make a similar table for any salt like those just by looking at the molecule and determining the nitrate ratio. For instance, the calcium nitrate molecule has two nitrates for one calcium. That has to be taken into account when calculating as this relationship makes it “nitrate heavy”.  This methodology can be used for other compounds as well. Another good example checmical is potassium chloride for dosing potassium in the tank, but without affecting nitrates. The idea is the same within the calculator.

Secondly, there is also a tab called Simple which allows for a quick and dirty calculation resembling the ones everyone is used to from the venerable Reef Chemisty Calculator, and others.

The Simple View tab answers the question “how many grams of potassium nitrate to add to the tank to increase by how many ppm”. This foregoes the middle step of creating a stock solution and dosing that one which might be useful when dosing with a pump.

All things considered, any method of adding it can work. If you want something simple, then just putting the recipe together from the post on Reef2Reef might be all you need. If you want to achieve more control, the calculator might be more your style.

Either way, keep your corals fed!