Chronic effects of sediment-induced changes in light quality (spectral shifts) and quantity on corals and sponges. (NESP TWQ 2.1.9, AIMS)

This dataset consists of one data file (spreadsheet) from a 28-d experiment examining sediment-induced changes in the spectral quality and quantity of light on three coral species (Acropora millepora, Pocillopora verrucosa and Montipora aequituberculata) and one encrusting sponge species (Cliona orientalis).

The aim of the study was to use ecologically relevant turbidity and light profiles obtained from field-based data to test the effects of sediment induced spectral shifts and quantities of light on corals and sponges. Data from this experiment will help to derive more realistic thresholds to be applied during dredging operations.

Methods:
Three coral species (Acropora millepora, Pocillopora verrucosa and Montipora aequituberculata) and one encrusting sponge species (Cliona orientalis) were used in SeaSim experiments to examine the effects of sediment induced changes in the quality and quantity of light. A. millepora and M. aequituberculata were collected from Falcon Island (18° 45’ 56.4”S; 146° 32’ 02.7”) and P. verrucosa and C. orientalis were collected from Pelorus Island (18° 45’ 36.7”S; 146° 29’18.5” E).

Corals were exposed to 5 different nominal suspended sediment concentrations (nominal SSC of 2.5, 5, 7.5, 10 and 15), with corresponding light profiles, for 28 days. Nephelometers used in the experimental tanks to maintain SSCs were calibrated with Formazin and set to measure Formazin Nephelometric Units (FNU), with water samples taken throughout the experiment (n=12) to relate FNU to SSCs (mg L-1). The gravimetric SSC was determined by filtering water samples (250 mL) through pre-weighed 0.4 µm polycarbonate filters, which were then rinsed with deionized water, dried at 60°C for 24 h and re-weighed. Photosynthetic active radiation (PAR) measurements were taken with a Jaz light meter (Jaz-ULM-200, Ocean Optics, the Netherlands) at peak intensity (12:00), with corresponding daily light integral (DLI) measurements obtained from the ramping profiles extracted from the programable logistic controller (PLC).

Several response variables were measured at the end of the 28-d experiment: color (mean grey pixel), symbiont density (total Zoox and Zoox/cm2), chlorophyll a content (µg/cm2 and pg/cell), percent total lipids, ratio of storage to structural lipids (Stor:Struct) and lipid classes (WAX, TAG, FFA, ST, AMPL, PE, PSPI, PC, LPC). 

All species were photographed using a high-resolution digital camera (Nikon D810) with the following settings: ISO-100, F-29 and shutter speed 1/200. Changes in colour were examined using the hitogram function in ImageJ to obain mean pixel intensity values on a black and white scale (range 0-255) of representative live tissue, as previously described (Bessell-Browne et al., 2017). 

Surface area (cm2) of the corals were calculated using the wax dipping method (Stimson and Kinzie, 1991). This value was used to standardize zooxanthellae density and chlorophyll concentrations. 

To determine symbiotic zooxanthellae density, a volume of 0.4 mm3 from each blastate aliquot was counted six times using a Neubauer haemocytometer containing 8 µL of homogenised solution.

Pigments were extracted using 95% ethanol and analysed on a Power Wave Microplate Scanning Spectrophotometer (BIO-TEK® Instruments, Inc., Vermont USA) as previously described (Pineda et al., 2016).
For lipid analyses, total lipids and lipid classes were acquired by extracting freeze-dried samples following the air-spraying method procedures of (Conlan et al. 2017). 

Response data for all coral species can be found in the ‘coral’ tab, while the data for C. orientalis can be found in the ‘Cliona’ tab. 

Format:
This dataset contains a single Excel file with a size of 96 KB.

Data Dictionary:

-SampleID: individual ID given to each replicate of the study
-Species:  Acropora millepora, Pocillopora verrucosa, Montipora aequituberculata
-Tank/Ta: holding, 1 -10
-Nominal SSC: nominal suspended sediment concentration selected in the spectral model
-Gravimetric SSC: actual suspended sediment concentration (mg L-1) corals/sponges were exposed to
-PAR: maximum light intensity (photosynthetic active radiation; µmol quanta m-2 s-1) corals/sponges were exposed to
-DLI: daily light integral (µmol quanta m-2 s-1) corals/sponges were exposed to
-Time: day sampled
-SA(cm2): surface area of the coral, calculated using the wax dipping method and used to standardize zooxanthellae density and chlorophyll concentrations. 
-Density of Zoox/cm2: density of zooxanthellae per cm2 tissue
-Total Zoox: total number of zooxanthellae
-pg Chl a/cell: picograms of chlorophyll a per zooxanthellae cell
-Total Chl a: total amount of chlorophyll a per cm2 tissue
-Mean grey pixel: mean grey pixel intensity value from imageJ analysis (0=black, 255=white)
-%Lipid: the percent total lipid
-WAX: percent wax ester (lipid class)
-TAG: percent triacylglycerol (lipid class)
-FFA: percent free fatty acid (lipid class)
-ST: percent sterol (lipid class)
-AMPL: percent acetone mobile polar lipid (lipid class)
-PE: percent phosphatidylethanolaimine (lipid class)
-PSPI: percent phosphatidylserine-phosphatidylinositol (lipid class)
-PC: percent phosphatidylcholine (lipid class)
-LPC: percent lyso-phosphatidylcholine (lipid class)
Stor:Struct: ratio of storage (WAX, TAG, FFA) to structural lipids (all other classes listed)

References:

Stimson, J., and Kinzie, R.A. (1991). The temporal pattern and rate of release of zooxanthellae from the reef coral Pocillopora damicornis (Linnaeus) under nitrogen-enrichment and control conditions. Journal of Experimental Marine Biology and Ecology 153, 63-74.

Bessell-Browne, P., Negri, A.P., Fisher, R., Clode, P.L., Duckworth, A., and Jones, R. (2017a). Impacts of turbidity on corals: The relative importance of light limitation and suspended sediments. Mar Pollut Bull 117, 161-170.

Pineda, M.C., Strehlow, B., Duckworth, A., Doyle, J., Jones, R., and Webster, N.S. (2016). Effects of light attenuation on the sponge holobiont- implications for dredging management. Sci Rep 6, 39038.

Conlan, J.A., Rocker, M.M., and Francis, D.S. (2017). A comparison of two common sample preparation techniques for lipid and fatty acid analysis in three different coral morphotypes reveals quantitative and qualitative differences. PeerJ 5, e3645.

Data Location:

This dataset is filed in the eAtlas enduring data repository at: data\nesp2\2.1.9_Dredging-marine-response

Organization: Australian Ocean Data Network