Attenuation of sunlight measured from moored radiometers to assess depletion of suspended particles caused by bivalve aquaculture

Ibarra, Diego; Cembella, Allan; Grant, Jon E.

doi:10.4319/lom.2012.10.1051

Cited by 3 publications

(7 citation statements)

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“…High densities of mussels may deplete food sources to such a level that production will be limited or growth will be anisotropically diminished. A consequence of maximizing biomass and filtration capacity is the depletion of phytoplankton and organic particles from the water column, potentially reducing light attenuation and scattering (Ibarra et al 2012, Schröder et al 2014, another primary objective of mitigation culture. Depletion will depend on not only stocking density or total biomass/filtering capacity of the mussels but will also depend on chemical and especially physical forcing (Stevens & Petersen 2011).…”

Section: Introductionmentioning

confidence: 99%

Evaluating chlorophyll depletion in mitigation mussel cultivation at multiple scales

Petersen¹,

Loo²,

Taylor³

2019

Aquacult. Environ. Interact.

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Section: Introductionmentioning

confidence: 99%

Evaluating chlorophyll depletion in mitigation mussel cultivation at multiple scales

Petersen¹,

Loo²,

Taylor³

2019

Aquacult. Environ. Interact.

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“…At ecosystem level, the effluents of mineral nutrients associated with the aquaculture activity can produce problems of eutrophication ( Ajin et al, 2016 ; Ruiz-Zarzuela et al, 2009 ). On the other hand, the loads of dissolved and particulate organic matter with the effluents can reduce water transparency due to an increase in light backscattering and absorption ( Ibarra, Cembella & Grant, 2012 ; Del Bel Belluz et al, 2016 ). Therefore, a sustainable aquaculture with effluents of low environmental impact is a global challenge for both scientists and food producers.…”

Section: Introductionmentioning

confidence: 99%

Sea cucumbers reduce chromophoric dissolved organic matter in aquaculture tanks

Sadeghi-Nassaj

Catalá

Álvarez³

et al. 2018

PeerJ

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BackgroundMono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM). A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named “extractive” species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown.MethodsDuring more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (−holothurian) only contained around 810 individuals of Anemonia sulcata, whereas the other tank (+holothurian) also included 90 individuals of Holothuria tubulosa and Holothuria forskali. We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes) optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H) and –holothurians (−H). We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four –H tanks that contained only 80 individuals of A. sulcata.ResultsIn the time-series, absorption coefficients at 325 nm (a325) and spectral slopes from 275 to 295 nm (S275−295) were significantly lower in the effluent of the +holothurian tank (average: 0.33 m−1 and 16 µm−1, respectively) than in the effluent of the −holothurian tank (average: 0.69 m−1 and 34 µm−1, respectively), the former being similar to those found in the inlet waters (average: 0.32 m−1 and 22 µm−1, respectively). This reduction in the absorption of the dissolved organic matter appears to be mediated by the POM consumption by holothurians. The experiments confirmed the results observed in the time-series. The a325 and S275−295 values were significantly lower in the treatment with holothurians than in the treatment without holothurians indicating a reduction in the concentration of chromophoric organic compounds, particularly of low molecular weight.DiscussionConsequently, sea cucumbers appear to improve water transparency in aquaculture tanks. The underlying mechanism of this improvement might be related to the POM consumption by holothurians, which reduces the concentration of CDOM derived from POM disaggregation or to the direct assimilation of dissolved compounds of low molecular weight as chromophoric amino acids.

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“…Indeed, CDOM optical properties in the tank with holothurians were quite similar to the inlet waters both quantitatively (absorption coefficients) and qualitatively (spectral slopes and ratios). Therefore, the presence of extractive species in offshore aquaculture installations could effectively increase water transparency by reducing light absorption and scattering (Ibarra et al 2012;Del Bel Belluz et al 2016). Monitoring CDOM optical properties is an easy and inexpensive procedure; which is very sensitive to the changes caused by the extractive species in multitrophic aquaculture.…”

Section: Resultsmentioning

confidence: 99%

“…At ecosystem level, the inputs of mineral nutrients associated with the aquaculture can produce problems of eutrophication (Ajin et al, 2016;Ruiz-Zarzuela et al, 2009). Moreover, the inputs of dissolved and particulate organic matter can reduce water transparency due to an increase in light backscattering and absorption (Ibarra et al 2012;Del Bel Belluz et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…As remote sensing has been suggested as an excellent tool to monitoring offshore aquaculture at large scales (Populus et al, 1995;Rajitha et al, 2007;Saitoh et al, 2011), the CDOM-chlorophyll a interference is important for the validation of those algorithms. However, the interaction between aquaculture and CDOM has been poorly explored (Ibarra et al 2012;Nimptsch et al 2015;Del Bel Belluz et al 2016). Sea cucumbers are extractive species with a high capacity to consume particulate organic matter (Nelson et al 2012a,b;Yokoyama 2013Yokoyama , 2015.…”

Section: Introductionmentioning

confidence: 99%

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Supplemental Information 1: CDOM and Ancillary Data of Inlet Water, Tanks and Effluents

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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 (a 325) and spectral slopes from 275 to 295 nm (S 275-295) 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

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Attenuation of sunlight measured from moored radiometers to assess depletion of suspended particles caused by bivalve aquaculture

Cited by 3 publications

References 46 publications

Evaluating chlorophyll depletion in mitigation mussel cultivation at multiple scales

Evaluating chlorophyll depletion in mitigation mussel cultivation at multiple scales

Sea cucumbers reduce chromophoric dissolved organic matter in aquaculture tanks

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