Influence of sea cucumbers on chromophoric of dissolved organic matter in multitrophic aquaculture tanks
- Published
- Accepted
- Subject Areas
- Aquaculture, Fisheries and Fish Science, Environmental Sciences
- Keywords
- sea cucumbers, extractive species, effluents, multitrophic aquaculture, chromophoric dissolved organic matter, particulate organic matter, water transparency
- Copyright
- © 2017 Sadeghi-Nassaj et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Influence of sea cucumbers on chromophoric of dissolved organic matter in multitrophic aquaculture tanks. PeerJ Preprints 5:e3012v1 https://doi.org/10.7287/peerj.preprints.3012v1
Abstract
Background. The effluents of the mono-specific aquaculture contain high concentrations of dissolved nutrients and organic matter, which affect negatively water quality of the recipient aquatic ecosystems. A key feature of water quality is its transparency. Chromophoric dissolved organic matter (CDOM) determines most of the light transmission in the ultraviolet and blue bands in the aquatic ecosystems. A sustainable alternative to mono-specific aquaculture is the integrated multitrophic aquaculture that includes species trophically complementary named “extractive” species. Sea cucumbers are recognized as efficient extractive species, with a high potential to improve water quality, due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown. Methods. During one year, we biweekly monitored CDOM in two aquaculture tanks with different trophic structure. One of the tanks (-holothurian tank) only contained the primary species, Anemonia sulcata, whereas the other tank (+ holothurian tank) also contained individuals of Holothuria tubulosa and H. forskali. We routinely performed CDOM absorption spectra from 200 nm to 750 nm and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes and molar absorption coefficients at 325 nm) optical parameters in the inlet waters, in the tanks, and in their corresponding effluents. Results. Absorption coefficients at 325 nm (a325) and spectral slopes from 275 to 295 nm (S275-295) were significantly lower in the effluents of the +holothurian tank (average: 0.33 and 16 μm-1, respectively) than in the effluents of the −holothurian tank (average: 0.69 m-1 and 34 μm-1, respectively), being the former similar to those found in the inlet waters (average: 0.32 m-1 and 22 μm-1, respectively). This reduction in CDOM absorption appears to be mediated by the POM consumption by the holothurians. The reduction of POM concentration in the +holothurian tank may weaken the process of POM disaggregation into dissolved organic matter, which ultimately might have generated CDOM in the –holothurian tank. Discussion. Extractive species such as holothurians improve water transparency through POM consumption, likely because reduces POM disaggregation into CDOM. We suggest that CDOM monitoring in aquaculture facilities, using automatic probes or even remote sensing, could be a useful tool to trace the effectiveness of extractive species at large scales of time and space.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
CDOM and ancillary data of inlet water, tanks and effluents
Table S1. CDOM and ancillary data of inlet water. The a 325 values are the absorption coefficients at wavelength 325 nm (m-1), the S275-295 values are the spectral slopes at the wavelength band from 275 to 295 nm (μm-1), SR is the ratio of the slope between 275 and 295 nm divided by the slope between 350 and 400 nm (unitless) and the a*325 values are the molar absorption coefficients at wavelength 325 nm (mg C l-1m-1). TOC is total organic carbon in mg C l-1, POM is particulate organic carbon in mgl-1, chl a is the concentration of chlorophyll a in μg l-1 and BA is the bacterial abundance in (x106 cells ml-1). x-no datum
Table S2. CDOM and ancillary data of the +holothurian effluent water. The a 325 values are the absorption coefficients at wavelength 325 nm (m-1), the S275-295 values are the spectral slopes at the wavelength band from 275 to 295 nm (μm-1), SR is the ratio of the slope between 275 and 295 nm divided by the slope between 350 and 400 nm (unitless) and the a*325 values are the molar absorption coefficients at wavelength 325 nm (mg C l-1m-1). TOC is total organic carbon in mg C l-1, POM is particulate organic carbon in mgl-1, chl a is the concentration of chlorophyll a in μgl-1 and BA is the bacterial abundance in (x106 cells ml-1).
Table S3. CDOM and ancillary data of the -holothurian effluent water. The a 325values are the absorption coefficients at wavelength 325 nm (m-1), the S275-295 values are the spectral slopes at the wavelength band from 275 to 295 nm (μm-1), SR is the ratio of the slope between 275 and 295 nm divided by the slope between 350 and 400 nm (unitless) and the a*325values are the molar absorption coefficients at wavelength 325 nm (mg C l-1m-1). TOC is total organic carbon in mg C l-1, POM is particulate organic carbon in mgl-1, chl a is the concentration of chlorophyll a in μgl-1 and BA is the bacterial abundance in (x106 cells ml-1).
Table S4. CDOM and ancillary data of the +holothurian tank water. The a 325values are the absorption coefficients at wavelength 325 nm (m-1), the S275-295 values are the spectral slopes at the wavelength band from 275 to 295 nm (μm-1), SR is the ratio of the slope between 275 and 295 nm divided by the slope between 350 and 400 nm (unit less) and the a*325values are the molar absorption coefficients at wavelength 325 nm (mg C l-1m-1). TOC is total organic carbon in mg C l-1, POM is particulate organic carbon in mgl-1, chl a is the concentration of chlorophyll a in μgl-1 and BA is the bacterial abundance in (x106 cells ml-1).
Table S5. CDOM and ancillary data of the -holothurian tank water. The a 325values are the absorption coefficients at wavelength 325 nm (m-1), the S275-295 values are the spectral slopes at the wavelength band from 275 to 295 nm (μm-1), SR is the ratio of the slope between 275 and 295 nm divided by the slope between 350 and 400 nm (unit less) and the a*325values are the molar absorption coefficients at wavelength 325 nm (mg C l-1m-1). TOC is total organic carbon in mg C l-1, POM is particulate organic carbon in mgl-1, chl a is the concentration of chlorophyll a in μgl-1 and BA is the bacterial abundance in (x106 cells ml-1).
Raw data of CDOM spectra
Raw data of CDOM spectra