Controlling Cyano - Page 2

Dan_P · 08/19/2018, 01:21 AM

Since no one actually measures the level of dissolved organic matter in their aquarium, it is impossible to say whether it causes cyanobacteria growth or that reducing the level impacts growth. There is also the questionable assumption that measuring the concentration of something in the bulk water is correlated to its concentration locally, e.g., at the surface of the substrate or rock.

Below is an abstract that seems to support the importance of organic matter. Not sure it will help because we can’t measure dissolved organic matter levels and if you can’t measure there is no way you can tell how anything you change is acting on them or which ones. That being said, GAC, wet skimmiming and water changes, bacteria growth and cutting back on feeding (GFO also adsorbs organics as does aragonite) seem to be our main tools for lowering dissolved organic matter.

Organic Matter Degradation Drives Benthic Cyanobacterial Mat Abundance on Caribbean Coral Reefs
Hannah J. Brocke , Lubos Polerecky, Dirk de Beer, Miriam Weber, Joachim Claudet, Maggy M. Nugues
Published: May 5, 2015 https://doi.org/10.1371/journal.pone.0125445
Abstract
Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised areas. Reefs with high BCM abundance were also characterised by high benthic cover of macroalgae and low cover of corals. Nutrient concentrations in the water-column were consistently low, but markedly increased just above substrata (both sandy and hard) covered with BCMs. This was true for sites with both high and low BCM coverage, suggesting that BCM growth is stimulated by a localised, substrate-linked release of nutrients from the microbial degradation of organic matter. This hypothesis was supported by a higher organic content in sediments on reefs with high BCM coverage, and by an in situ experiment which showed that BCMs grew within days on sediments enriched with organic matter (Spirulina). We propose that nutrient runoff from urbanised areas stimulates phototrophic blooms and enhances organic matter concentrations on the reef. This organic matter is transported by currents and settles on the seabed at sites with low hydrodynamics. Subsequently, nutrients released from the organic matter degradation fuel the growth of BCMs. Improved management of nutrients generated on land should lower organic loading of sediments and other benthos (e.g. turf and macroalgae) to reduce BCM proliferation on coral reefs.

08/19/2018, 01:21 AM	#26
Dan_P Registered Member Join Date: Aug 2014 Posts: 1,432	Since no one actually measures the level of dissolved organic matter in their aquarium, it is impossible to say whether it causes cyanobacteria growth or that reducing the level impacts growth. There is also the questionable assumption that measuring the concentration of something in the bulk water is correlated to its concentration locally, e.g., at the surface of the substrate or rock. Below is an abstract that seems to support the importance of organic matter. Not sure it will help because we can’t measure dissolved organic matter levels and if you can’t measure there is no way you can tell how anything you change is acting on them or which ones. That being said, GAC, wet skimmiming and water changes, bacteria growth and cutting back on feeding (GFO also adsorbs organics as does aragonite) seem to be our main tools for lowering dissolved organic matter. Organic Matter Degradation Drives Benthic Cyanobacterial Mat Abundance on Caribbean Coral Reefs Hannah J. Brocke , Lubos Polerecky, Dirk de Beer, Miriam Weber, Joachim Claudet, Maggy M. Nugues Published: May 5, 2015 https://doi.org/10.1371/journal.pone.0125445 Abstract Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised areas. Reefs with high BCM abundance were also characterised by high benthic cover of macroalgae and low cover of corals. Nutrient concentrations in the water-column were consistently low, but markedly increased just above substrata (both sandy and hard) covered with BCMs. This was true for sites with both high and low BCM coverage, suggesting that BCM growth is stimulated by a localised, substrate-linked release of nutrients from the microbial degradation of organic matter. This hypothesis was supported by a higher organic content in sediments on reefs with high BCM coverage, and by an in situ experiment which showed that BCMs grew within days on sediments enriched with organic matter (Spirulina). We propose that nutrient runoff from urbanised areas stimulates phototrophic blooms and enhances organic matter concentrations on the reef. This organic matter is transported by currents and settles on the seabed at sites with low hydrodynamics. Subsequently, nutrients released from the organic matter degradation fuel the growth of BCMs. Improved management of nutrients generated on land should lower organic loading of sediments and other benthos (e.g. turf and macroalgae) to reduce BCM proliferation on coral reefs.