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!

Biological control of aragonite formation in stony corals

Biological control of aragonite formation in stony corals

Stanislas Von Euw1, Qihong Zhang, Viacheslav Manichev, Nagarajan Murali, Juliane Gross, Leonard C. Feldman, Torgny Gustafsson, Carol Flach, Richard Mendelsohn, Paul G. Falkowski

Science  02 Jun 2017:
Vol. 356, Issue 6341, pp. 933-938
DOI: 10.1126/science.aam6371

PDF Available

[…]mineral precipitation in corals is a biologically controlled process mediated by organic molecules, rather than an abiotic one that depends only on physico-chemical conditions.

[…]biomineralization in stony corals is not simply related to physicochemical parameters such as the equilibrium saturation state of carbonate ions or the bulk pH of seawater (33).

Nitrogen cycling in corals: the key to understanding holobiont functioning?

Nitrogen cycling in corals: the key to understanding holobiont functioning?

Nils Rädecker, Claudia Pogoreutz, Christian R. Voolstra, Jörg Wiedenmann, Christian Wild

Trends in Microbiology, Vol. 23, Issue 8, p490–497

  • Nitrogen cycling in reef-building corals is a function of all holobiont members.
  • Control of nitrogen cycling may stabilize holobiont functioning under oligotrophic and eutrophic conditions.
  • Anthropogenic change may sway the control of nitrogen cycling, promoting coral decline.
  • Elevated nitrogen fixation rates may foster coral bleaching and disease.

Point for point comments:

  • In aquariums this is what makes corals resilient to our manual attempts to re-create oligotrophic conditions in an overstocked tank.
  • Witness the threads on paling corals and other issues.  KNO3 dosing is often seen these days.  Corals are apparently healthier when some NO3 is present.
  • In the ocean, anthropogenic NO3 additions cause bad PO4 limiting among other things….corals and everything else tend to decline under PO4 starvation.
  • There’s no free lunch…even within successful ecosystems, higher bio-loads come with a higher risk.

The rest of the article is a great read too….tons of more reading is linked within the article too.

Coral aquaculture: applying scientific knowledge to ex situ production

Coral aquaculture: Applying scientific knowledge to ex situ production

Reviews in Aquaculture 6(2) · October 2014
DOI: 10.1111/raq.12087

Article (PDF Available)

Miguel Costa Leal, Christine Ferrier-Pagès, Dirk Petersen, Ronald Osinga

Still have to read the rest, but this was enough to hook me:

Although captive breeding and propagation of corals is a well-known activity among aquarium hobbyists and public aquariums, the link between coral science and aquaculture is still poorly developed.
Amen to that, but it’s not for a lack of trying!  We are here!!
This appears, even from our perspective, to be a very complete review of keeping and propagating corals in aquariums (“ex situ”) so please save me a ton of quotes – click and read!

Putting the N in dinoflagellates

Putting the N in dinoflagellates

Steve Dagenais-Bellefeuille and David Morse

Front Microbiol. 2013; 4: 369.
Published online 2013 Dec 4.

doi: 10.3389/fmicb.2013.00369

Creative Commons license.

There are so many “Wow”‘s in this review that I’m just going to quote like a demon and be thankful that the article is under a Creative Commons license from the cited authors.

Their story begins when dino’s radiate about 400 million years ago after the late Devonian extinction.

Some choice quote and a little commentary..

In conditions of N-stress dinoflagellate cells either die or modify their metabolism and trophic behavior to ensure their survival.

The original motive for the bloom.

The marine N cycle is probably the most complex of the biogeochemical cycles, as it involves various chemical forms and multiple transformations that connect all marine organisms.

Cool fact.

About 94% of the oceanic N inventory exists as biologically unavailable dissolved nitrogen gas (N2; Gruber, 2008). This gas can be made bioavailable through N2-fixation, a process carried out by photoautotrophic prokaryotes, mainly cyanobacteria, using iron-dependent nitrogenases to catalyze reduction of N2 to NH+4.

Didn’t know that much N was dissolved gas.

Didn’t know nitrogen fixation was iron-dependent.

Generally, when growing in presence of various different N compounds, dinoflagellates (as well as plants and algae) prefer to take up NH+4. However, there is a concentration threshold above which NH+4 becomes toxic to the cells[…]

Cool fact.

Another tendency in dinoflagellates is inhibition of NO−3 uptake when in the presence of NH+4.


Curiously, different blooming populations of dinoflagellates were found to have high uptake rates for urea and/or amino acids, and these rates were always higher than the rates for NO−3 uptake (Kudela and Cochlan, 2000; Fan et al., 2003; Collos et al., 2007).

So there is some basis for the theory that amino acids “cause” or are related to HAB’s

Dinoflagellates often display a diurnal vertical migration (DVM) in the water column and, because NO−3 concentrations increase with depth, dark NO−3 uptake was first described as a means to sustain uninterrupted growth by meeting their N requirements under conditions where the cells cannot photosynthesize (Harrison, 1976). It was further suggested that the DVM of dinoflagellates gave them a competitive advantage for N uptake over the non-motile diatoms (Harrison, 1976; Smayda, 1997).


We will finish with a model proposed by Jeong et al. (2010) where mixotrophy explains the outbreak and persistence of HABs in aquatic ecosystems limited in inorganic nutrients.


Spectacularly, some pallium and peduncle feeders are able to ingest prey up to 10 times their size (Jacobson, 1987). As for prey types, MTDs and HTDs feed on a wide array of taxa. They were shown to ingest cryptophytes, haptophytes, chlorophytes, prasiophytes, raphidophytes, diatoms, heterotrophic nanoflagellates, ciliates, and other dinoflagellates (Jacobson and Anderson, 1986; Hansen, 1991; Bockstahler and Coats, 1993b; Strom and Buskey, 1993; Nakamura et al., 1995; Tillmann, 2004; Jeong et al., 2005a, 2008; Menden-Deuer et al., 2005; Adolf et al., 2007; Berge et al., 2008). However, while some HTDs can feed on blood, flesh, eggs and early naupliar stages and adults forms of metazoans, no MTDs have been shown to do so (Miller and Belas, 2003; Parrow and Burkholder, 2004; Jeong et al., 2007).


It was long believed that bacteria were too small to be ingested by dinoflagellates. In the last few years, however, fluorescence and transmission electron microscopy observations revealed that multiple HTDs and MTDs were able to feed on heterotrophic bacteria and cyanobacteria (Jeong et al., 2005a, 2008; Seong et al., 2006; Glibert et al., 2009). In particular, feeding on the N2-fixing Synechococcus spp. was seen in 18 species reported to form HABs (Jeong et al., 2005a; Seong et al., 2006; Glibert et al., 2009). Generally, when prey concentration was high (106 cells/ml), the ingestion rates increased with increasing size of the dinoflagellate predators (Jeong et al., 2005a). Moreover, ingestion rates of Synechococcus were comparable to those observed in heterotrophic nanoflagellates (Seong et al., 2006). A mixture of P. mininum and P. donghaiense was able to remove up to 98% of the Synechococcus population within 1 h, showing that grazing by these species on bacteria could be very substantial (Jeong et al., 2005a). Thus, bacterivory in dinoflagellates was suggested to be a cause of HABs outbreaks and persistence in nutrient-limited waters (Glibert et al., 2009; Jeong et al., 2010). A model was further proposed where MTDs would supply their N requirement by ingesting cyanobacteria, while meeting their P requirement by ingesting heterotrophic bacteria, which are reported to generally have a high P:N ratio (Jeong et al., 2010). This model as yet to be tested in the environment.


Symbiosis with diazotrophs is an example of a strategy that is shared by some diatom and dinoflagellate species. The diatom genera Hemiaulus and Rhizosolenia both form endosymbiotic associations with the cyanobacteria Richelia intracellularis (Venrick, 1974; Carpenter et al., 1999). Both the hosts and the symbionts were observed to bloom together in the oligotrophic waters of the North Pacific Central Gyre and South West Atlantic Ocean. N2-fixation by Richelia introduced an amount of “new N” to the ecosystems that could even exceed the N2 fixed by non-blooming Trichodesmium. Carpenter et al. (1999) suggested that the silicate- and iron-enriched water of the Amazon River could have been factors in initiating and sustaining the blooms in the SW Atlantic Ocean. Silicate is required for the formation of the diatom frustule, while iron is necessary for the action of the diazotroph nitrogenases.


While it was not directly shown that Symbiodinium formed symbiotic association with cyanobacteria, the coral host was found to do so. In fact, whole communities of beneficial bacteria including N2-fixers and chitin decomposers were identified in all coral structures, including the surface mucous layer, tissue layers and the skeleton (Lesser et al., 2004; Rosenberg et al., 2007). Interestingly, amplification of the nitrogenase gene nifH in tissues of 3 different coral species revealed that 71% of the sequences came from a bacterial group closely related to rhizobia, the N2-fixers symbiotic with legumes (Lema et al., 2012). The products of N2-fixation were initially assimilated by the zooxanthellae, then translocated to the animal host, as determined by δ15N analysis (Lesser et al., 2007). Moreover, Symbiodinium population density was positively correlated with nifH sequence copy number, suggesting that growth and division of the zooxanthellae might be dependent upon the product of N2-fixation (Olson et al., 2009). Taken together, these examples suggest that the cyanobacteria barter their N2-fixing ability for protection and nutrients from their hosts, thus providing a selective advantage to the hosts in N-limited environments.


Technological improvements for the cultivation of invertebrates as food for fishes and crustaceans. II. Hatching and culturing of the brine shrimp, Artemia salina L

Technological improvements for the cultivation of invertebrates as food for fishes and crustaceans. II. Hatching and culturing of the brine shrimp, Artemia salina L

From p311-312.

Apparently, for small-batch brine shrimp culture (useful size), they used funnel-shaped vessels as small as 100mL and up to one liter.  For maximum results, they only bubbled the medium in 5 second bursts four times an hour.

Feeding corals in captivity: uptake of four Artemia- based feeds by Galaxea fascicularis

Feeding corals in captivity: uptake of four Artemia- based feeds by Galaxea fascicularis

Ronald Osinga, Fam Charko, Catarina Cruzeiro, Johan A.J. A.J. Verreth

(PDF Download Available)

This study evaluates the capture efficiency of the scleractinian coral Galaxea fascicularis for four Artemia-based feeds: (1) live, non-enriched Artemia nauplii; (2) Instant Baby Brine Shrimp (IBBS, pasteurized Artemia nauplii); (3) live, SELCO-enriched Artemia nauplii, and (4) live Artemia nauplii enriched with SELCO that was supplemented with the antibiotics Sulfamethoxazole and Trimethoprim. All prey types were rapidly consumed by the corals (6-11 nauplii per polyp per hour), showing that (I), IBBS can be a cost-effective alternative to feeding freshly hatched nauplii, and (II), corals can be provided with specific additives via their food. The corals preferred live Artemia over IBBS, indicating that IBBS can be further optimised for use in coral reef aquaria. SELCO-enriched Artemia and medicated Artemia were also consumed at lower rates (40% and 30% lower, respectively) than non-enriched Artemia.

General interest!  This applies to us so directly it’s almost not worth commenting!

Ocean Nutrition sells instant baby brine shrimp and I have used them before.  I’m going to get more for backups in between hatches of live!