Symbiodinium (AKA zooxanthellae) is the engine that spurs much of coral reef growth. From anatomy to clades, parasitic zoox to coral fidelity, Dana Riddle updates us on this powerhouse symbiont.
Dana Riddle's sixth Coral Nutrition article examines the effect of alkaline earth (e.g. calcium and strontium) and other metals on corals – including some rather surprising information.
Back in 2005 I first read about Dendronephthya corals, notorious for being difficult to maintain in aquaria. Lacking zooxanthellae, these corals require plankton to stay healthy. In the following years, I read up on the scientific literature, and toyed with the idea of setting up an aquarium specifically designed for Dendronephthya. This led to the launch of a crowd funding project on Indiegogo, to acquire funds for the development of a culture protocol for Dendronephthya corals. Although insufficient funds were gathered to fully develop an aquaculture system and culture protocol, two preliminary experiments were conducted. In this article, I will present the results of these experiments, and provide future directions for research. This may help aquarists to keep pushing the frontier of coral husbandry and aquaculture.
Decreased growth of Stylophora pistillata with nutrient-driven elevated zooxanthellae density is largely explained by DIC limitation
High nutrient concentrations are generally known to adversely affect coral calcification. This reduction in calcification rate is often associated with increased zooxanthellae densities, but little is known about the mechanism underlying calcification inhibition. In this study, we assessed the limiting effects of dissolved inorganic carbon (DIC) on growth rates of Stylophora pistillata before and after five weeks of nitrogen and phosphorus enrichment. Nutrient enrichment resulted in a significant increase in zooxanthellae density and inhibition of calcification, measured using the alkalinity anomaly technique. DIC limitation was the main causative factor for this inhibition; a doubling of the bicarbonate concentration not only restored but greatly enhanced calcification rates of colonies with elevated zooxanthellae densities. At high bicarbonate concentration, no significant negative effect of nutrient enrichment on coral growth was found. The causal mechanism behind calcification inhibition due to nutrient enrichment is most likely increased competition for dissolved inorganic carbon, either among the zooxanthellae or between the coral host and its symbiotic dinoflagellates. This highly limiting effect of DIC on coral growth at elevated nutrient concentrations has important implications for coral aquaculture and husbandry.
Dana Riddle continues his intensive exploration of coral nutrition. In part three of his series, he delves deep into the subject of amino acids, including a discussion about amino acid supplements marketed to reefkeepers.
Stony coral nubbins (tentatively identified as Porites lobata; see Figure 1) were exposed to light of the same intensity (128 µmolm²sec) but different spectra for 75 days. Growth rates were determined by weighing the fragments periodically with an analytical balance.
Over the last decades, the husbandry of aquarium corals has risen to a high level. Although captive corals currently exhibit high survival and fast growth, sexual reproduction remains a major hurdle. Closing the life cycle of corals is an important next step in coral husbandry and aquaculture. Below, I will discuss the reproductive biology of scleractinian corals, the challenges associated with sexual reproduction, and future perspectives of coral aquaculture.
Black corals, formally known as Antipatharia, are members of a unique order within the Anthozoa class. These hexacorals are regularly found in the aquarium trade, and are often misidentified as gorgonians. In this article, we discuss the biology of black corals, and offer some suggestions for aquarium husbandry.
Are reefkeepers striving for the right levels of pH, alkalinity, and calcium? Using PAM fluorometry, Christie D. Raji studies the effects of high and low levels of each of these parameters on hermatypic corals in a captive environment.
When aquarist think about reef animals, cerianthids usually don't come to mind. However, tube anemones are some of the most beautiful, hardy, and long-lived organisms for captive aquariums, and they're not as dangerous to tankmates as many believe.
Amino acids are a popular ingredient in aquarium additives nowadays, with many advertised beneficial effects on corals. In this article, I will provide some basic information about amino acids, and discuss their documented roles in coral biology. This will help the aquarist to make an informed decision about using concentrated amino acid as supplements for the marine aquarium.
Dana delves into the the science behind coral coloration by examining the fluorescent proteins in Clade D corals including Echinophyllia, Favia, Favites, Galaxea, Lobophyllia, Montastraea, Plesiastrea, Ricordea, Scolymia, Trachyphyllia, and others.
Overall toadstools are attractive, hardy, and easy to propagate, making it easy to see why they are a long-time hobby favorite.
It is common knowledge that many coral species depend on their symbiotic zooxanthellae to survive. Their alliance with these dinoflagellates has allowed corals to build vast underwater structures known as coral reefs, in an environment that seems almost devoid of nutrients. Research has shown that, in addition to energy gained from photosynthesis, plankton constitutes an important source of nutrients for corals. Although zooplankton supplementation may significantly enhance their growth, new findings suggest that corals are best fed when the aquarium lights are on.
We will look at colors of some of the most popular reef aquarium corals - Acropora species (Family Acroporidae). There is a considerable amount of relatively new information presented in this article.
Flatworms are well-known in the aquarium hobby and research community. Both in the wild and in captivity, they hide between the tentacles of many corals. Despite their common appearance in aquaria, the nature of the symbiosis between corals and flatworms has long been unclear. New evidence strongly suggests that epizoic acoelomorph flatworms are parasitic. Next to suffocating coral tissue and feeding on coral mucus, flatworms have now been found to impair coral feeding.
James describes the many species of one our hobby's most iconic and popular coral genus, Euphyllia, and discusses their merits, pitfalls, and husbandry requirements.
Often overlooked and underappreciated, the Atlantic biotopes are amazing aquariums. Sustainable inhabitants are here in our own backyards and ready for hobbyists to create new and interesting aquariums. Much can be learned about these animals from captive systems and hobbyists have a remarkable opportunity in front of them to participate in the process and progress.
Aquarium Invertebrates: Phestilla Nudibranchs: Cryptic Enemies of Porites, Goniopora, Tubastrea and Dendrophyllia Corals and an Identification of 'Montipora-eating Nudibranchs'
Dana takes us on an in-depth look at the Phestilla and Embletonia nudibranchs that can wreak havoc on an unsuspecting coral in your tank.
Aiptasia are tropical sea anemones which are commonly found in marine aquaria. Usually introduced as hitchhikers on live rock, they rapidly colonize the aquarium due to their prolific growth. Although Aiptasia may settle on any available substrate, chemical signals may attract them to specific microhabitats. In this article I report on the settlement preference of Aiptasia for cyanobacterial mats, a finding which suggests a three-way symbiosis between sea anemones, dinoflagellate algae and bacteria.