Dataset: Damselfish Turf Biomass

Name: [DRAFT] The biomass of turf samples in damselfish territory before and after treatment with fertilizer in Mo'orea, French Polynesia from June to July 2025
Published: 2025-02-04
Keywords: algal turfs, coral reef, damselfish, herbivory, biota, oceans

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Spatial Extent: N:-17.478306 E:-149.83925 S:-17.478306 W:-149.83925

Moorea, French Polynesia (17°28'41.9"S 149°50'21.3"W), depth < 3m

Temporal Extent: 2025-06-13 - 2025-07-14

Project:

Positive Effects of Coral Biodiversity on Coral Performance: Patterns, Processes, and Dynamics (Coral Biodiversity)

Principal Investigator:

Mark E. Hay (Georgia Institute of Technology, GA Tech)

Student:

Noam T Altman-Kurosaki (Georgia Institute of Technology, GA Tech)

Version:

Version Date:

2025-02-04

Restricted:

Current State:

Preliminary and in progress

[DRAFT] The biomass of turf samples in damselfish territory before and after treatment with fertilizer in Mo'orea, French Polynesia from June to July 2025

Abstract:

[drafted by Dana] A study to examine the effects of fertilizer addition on damselfish behavior was conducted in June and July 2025 in Mo'orea, French Polynesia. As part of a before-after control impact (BACI) experiment, algal turf samples from damselfish territories were sampled both before and after the experiment and analyzed for biomass and elemental composition.

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Description

This dataset is part of a larger study of the coral reef ecosystem in Mo’orea, French Polynesia that examines mechanisms governing interactions between damselfish, corals, and turf algae. The different analyses from the broader study are listed here, with links to these associated data in the 'Related Datasets' section below.

Analyses undertaken include:

Fertilizer impacts on damselfish behavior (Damselfish behavior video dataset 949539)
Fertilizer impacts on biomass plus isotopic composition of algal turfs (this dataset of damselfish turf biomass)
Fertilizer impacts on coral predation and herbivory (Corallivory dataset 9xxxxxx, Herbivory dataset 9xxxxx)
Impacts of fertilizer and caging on coral and algal growth (Coral growth dataset 9xxxxx, Algal overgrowth dataset 9xxxxxx)
Coral-turf allelopathy (Turf extracts PAM dataset 949219, Coral-algal contact dataset 9xxxxxx)
Species composition of turf gardens (Turf cover composition dataset + supplemental for Coral Reefs paper)

Methods & Sampling

More needed here?

Changes in traits of damselfish turfs were assessed by collecting six samples of turf that were about two centimeters square (~2 cm2) using a hammer and chisel from each damselfish territory both pre- and 14 days post-treatment. During each collection, three samples from each territory were used to assess biomass, and three were used to assess carbon to nitrogen ratio (C:N) of the turfs within each territory, resulting in 180 turf samples for each assessment of each treatment and timepoint. Exact dimensions of each turf sample were measured to the nearest millimeter. Turf filaments were removed from each sample via forceps in the lab and dried at 60°C until they reached a constant dry weight. Samples for biomass analysis were then ashed at 450°C in a muffle furnace until they reached a constant weight. Ash-free-dry mass was used to assess algal mass to avoid counting small bits of carbonate that were difficult to remove from all filaments. This was calculated as the difference between the mass of the sample before and after ashing and then standardized per unit area sampled (grams per square centimeter; g cm-2). Treatment effects on biomass were then assessed using gamma regression with a log link, with BACI fixed effects and random effects specified as above. ??? Model assumptions were again assessed using the Dharma package (Hartig 2022).

To minimize cost associated with analyzing turf elemental composition, we combined triplicates from each territory by subsampling 1 mg of dried turf from each of the “Day 14” samples, reducing the number of samples to 30 (n=15 per treatment). These samples were acid fumed to remove carbonate and analyzed with a continuous-flow isotope-ratio mass spectrometry (CF-IRMS) using a Micromass Optima interfaced to a CE Elantech NA2500 elemental analyzer. Algal tissue Carbon:Nitrogen (C:N) ratios were then compared between treatments using a linear mixed effects model with a random effect to account for spatial blocking. Model assumptions were assessed using the DHARMa package (Hartig 2022).

Data Processing Description

Treatment effects on biomass were then assessed using gamma regression with a log link, with BACI fixed effects and random effects specified as above. ??? Model assumptions were again assessed using the DHARMa package (Hartig, 2022).

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1947522

Deployments

None available yet

Instruments

Continuous Flow Interface for Mass Spectrometers

Supplied Name: CF-IRMS interface

Supplied Description:

Algal turf samples were analyzed with a continuous-flow isotope-ratio mass spectrometry interfaced to an elemental analyzer.

Instrument Type

Generic Name: Continuous Flow Interface for Mass Spectrometers

Generic Description:

A Continuous Flow Interface connects solid and liquid sample preparation devices to instruments that measure isotopic composition. It allows the introduction of the sample and also reference and carrier gases.
Examples: Finnigan MATConFlo II, ThermoScientific ConFlo IV, and Picarro Caddy.

Note: This is NOT an analyzer

Elemental Analyzer

Supplied Name: CE Elantech NA2500 elemental analyzer

Supplied Description:

Algal turf samples were analyzed with a continuous-flow isotope-ratio mass spectrometry interfaced to a CE Elantech NA2500 elemental analyzer.

Instrument Type

Generic Name: Elemental Analyzer

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB01/

Generic Description:

Instruments that quantify carbon, nitrogen and sometimes other elements by combusting the sample at very high temperature and assaying the resulting gaseous oxides. Usually used for samples including organic material.

Isotope-ratio Mass Spectrometer

Supplied Name: Micromass Optima interfaced to an elemental analyzer

Supplied Description:

Algal turf samples were analyzed with a continuous-flow isotope-ratio mass spectrometry (CF-IRMS) using a Micromass Optima interfaced to an elemental analyzer.

Instrument Type

Generic Name: Isotope-ratio Mass Spectrometer

Acronym: IR Mass Spec; IRMS

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB16/

Generic Description:

The Isotope-ratio Mass Spectrometer is a particular type of mass spectrometer used to measure the relative abundance of isotopes in a given sample (e.g. VG Prism II Isotope Ratio Mass-Spectrometer).

Manual Biota Sampler

Supplied Name: hammer and chisel

Supplied Description:

Algal turfs were collected using a hammer and chisel to obtain six samples that were two centimeters square.

Instrument Type

Generic Name: Manual Biota Sampler

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/90/

Generic Description:

"Manual Biota Sampler" indicates that a sample was collected in situ by a person, possibly using a hand-held collection device such as a jar, a net, or their hands. This term could also refer to a simple tool like a hammer, saw, or other hand-held tool.

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
Date	Date of sample collection Format: %Y-%m-%d	unitless	date
Sample_num	Sample number of the turf sample	unitless	sample
Territory	Territory number	unitless	site_descrip
Pair	Spatial pair for a given set of damselfish territories (A through O); used for spatial blocking	unitless	site_descrip
Pre_post_trt	Indicates whether biomass sample was collected before (pre-) or after (post-) treatment with fertilizer	unitless	time_sample
Fertilized	Indicates if territory had fertilizer applied to it (Y) or was a control (N)	unitless	treatment
Replicate	Indicates measurements for a given turf triplicate used in biomass measurements	unitless	replicate
Length	Length of turf sample	centimeters (cm)	length
Width	Width of turf sample	centimeters (cm)	width
Area	Calculated area of turf sample (from length x width)	square centimeters (cm^2)	area
Dry_weight_lab	Dry weight of turf sample measured in the lab in Atlanta	grams (g)	dry_weight_biomass
AFDW	Ash free dry weight; the weight of the sample after being ashed in the muffle furnace	grams (g)	weight
Biomass	Dry weight minus ash free dry weight	grams (g)	weight

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Dataset: Damselfish Turf Biomass