Ash-free Dry Weight Research Articles

Impact of harvesting method on total lipid content and extraction efficiency for Phaeodactylum tricornutum

Abstract Flocculation is a promising low-cost alternative to centrifugation for harvesting microalgae for bulk lipid production. However, little is known about the effect of the harvesting method on the lipid content on the one hand and the lipid extraction efficiency on the other hand. In this study, both total lipid content (and fatty acid composition and free fatty acid amount) and lipid extraction efficiency of Phaeodactylum tricornutum biomass were compared after harvesting using either alum or alkaline flocculation, or centrifugation. Alum and alkaline flocculation did not severely impact total lipid content when expressing results on ash-free dry weight basis to account for the salts transferred to the biomass during flocculation. The fatty acid composition does not change substantially and alum nor alkaline flocculation had any effect on the extraction efficiency when using a commercial solvent system. This study demonstrates that alkaline flocculation can be an excellent primary harvesting method for Phaeodactylum tricornutum without impacting the lipid extraction efficiency.

Recycled wastewater from anaerobic digestion of lipid extracted algae as a source of nutrients

Nutrient supply, especially nitrogen and phosphorus, is one of the key obstacles limiting industrialization of algal biofuel. To help enhance nutrient utilization efficiency, our research focused on recycling of nutrients from lipid extracted algae biomass by the method of anaerobic digestion. Two methods of lipid extraction were performed, nutrients were released during anaerobic digestion of the lipid extracted biomass, the recycled nutrients were collected for algae cultivation, and the cycle was repeated: cultivation-extraction-digestion-cultivation. The results show that anaerobic digestion released nitrogen and phosphorus, and methane as a gaseous by-product. The algae grew well on the recycled nutrients. Ammonia is the limiting macro element, and extra trace elements enhanced algae production as well. Ash free dry weight, lipid content and lipid components were monitored and did not vary when the cycle was repeated. This system for recycling nutrients with supplementary nutrients holds potential for producing biofuel from algae.

Scenedesmus obliquus mediated brewery wastewater remediation and CO2 biofixation for green energy purposes

Microalgae can be used for wastewater bioremediation with simultaneous CO2 biofixation producing valuable biomass.Wastewater from a brewery was treated using the Scenedesmus obliquus microalga in bubble-column photobioreactors (PBRs). The PBRs were fed with ambient air and the effect of a 10% (v/v) brewery CO2 supplement was studied. The PBRs were inoculated and a range of mean hydraulic residence time (HRT) values were tested (2.1–10.4 days). The maximum ash-free dry weight (AFDW) biomass productivity was obtained for a HRT of 3.5 days (0.29 d−1 dilution rate; 0.2 g L−1 d−1 (in terms of AFDW). The highest pollutant removal efficiencies were 92.9 and 88.5% for ammonia and total nitrogen, respectively, 40.8% for phosphorus, and 61.9% for COD. Except a dilution rate of 0.48 d−1 trial, the treated wastewater always met the Portuguese legislation quality standard for discharge into natural water bodies. Aiming to simultaneously maximize biomass volumetric productivity, CO2 biofixation rate and wastewater treatment efficiency, while minimizing residence time, 0.29 d−1 represents the optimal dilution rate value.The potential of the produced Scenedesmus obliquus biomass was evaluated for the generation of biohydrogen through dark fermentation with Enterobacter aerogenes, and of bio-oil, bio-char and bio-gas through a pyrolysis process. The yields obtained were 67.1 mL H2 g−1 (in terms of volatile solids - VS) for bioH2 and 64, 30 and 6% for bio-oil, bio-char and bio-gas, respectively (dry mass content (%) calculated over freeze dryer biomass basis).

Effect of glyphosate acid on biochemical markers of periphyton exposed in outdoor mesocosms in the presence and absence of the mussel Limnoperna fortunei.

Glyphosate is currently the most widely used herbicide in agricultural production. It generally enters aquatic ecosystems through surface water runoff and aerial drift. We evaluated the effect of glyphosate acid on biochemical parameters of periphyton exposed to concentrations of 1, 3, and 6 mg/L in outdoor mesocosms in the presence and absence of the mussel Limnoperna fortunei. Periphyton ash-free dry weight, chlorophyll a content, carotene/chlorophyll a ratio, lipid peroxidation levels, and superoxide dismutase and catalase activities were determined at days 0, 1, 7, 14, and 26 of the experimental period. Ash-free dry weight was similar between control and glyphosate-treated periphyton in the absence of L. fortunei. The latter had significantly lower carotene to chlorophyll a ratios and enzyme activities, and higher lipid peroxidation levels and chlorophyll a content than the former. These results show an adverse effect of glyphosate on the metabolism of periphyton community organisms, possibly inducing oxidative stress. On the contrary, no differences were observed in any of these variables between control and glyphosate-treated periphyton in the presence of L. fortunei. Mussels probably attenuated the herbicide effects by contributing to glyphosate dissipation. The results also demonstrate that biochemical markers provide useful information that may warn of herbicide impact on periphyton communities. Environ Toxicol Chem 2017;36:1775-1784. © 2016 SETAC.

Seasonal Patterns of Recruitment of Juvenile Blue Crabs and Lesser Blue Crabs at a Coastal Site In Louisiana

ABSTRACT This research tested the null hypothesis that there is no seasonal variation in the recruitment, body size, and growth status of juvenile Callinectes sapidus and Callinectes similis at a soft sediment site at Port Fourchon, LA, which varied in collection salinity between 17 and 37. Monthly collections of 5- to 30.6-mm carapace width (CW) juvenile crabs were made with a push net between March 2007 and February 2009. Juvenile C. sapidus were primarily recruited in March 2007, November 2007 to February 2008, June and July 2008, and in December 2008 and January 2009, whereas the major recruitment times for C. similis were April–October 2007,March–May 2008, August through October 2008 and February 2009. The ratio of juvenile C. sapidus:C. similis was not significantly related to the ambient salinity at the time of collection. The average wet weight, dry weight, and ash-free dry weight of a standard 17.5-mm CW blue crab and lesser blue crab was determined monthly with second-degree polynomial (quadrati...

Lipid and chitin nanofiber production during cultivation of the marine diatom Cyclotella sp. to high cell density with multistage addition of silicon and nitrate

The centric marine diatom Cyclotella sp. requires silicon in the form of Si(OH)4 for cell wall biosynthesis, makes lipids for biofuels, and extrudes novel chitin nanofibers as a valued co-product for biomedical and nutraceutical applications. Due to the low solubility of Si(OH)4 in seawater (<2 mM), to achieve high cell number density, dissolved Si was added in steps, with Si consumption between each step. A multistage nutrient delivery process with 19 mM cumulative Si delivery achieved a cell number density of 4 · 107 cells mL−1 (5.0 g ash-free dry weight (AFDW) L−1), ten times higher than that of the two-stage Si addition process. Cell number and chitin production profiles were linear with time, commensurate with the Si consumption profile. The productivities of biomass and chitin were 0.29 g AFDW L−1 day−1 and 45 mg chitin L−1 day−1, with chitin yield of 19 wt% in the biomass. Lipid production could not be sustained due to light attenuation, and yield decreased from 39 wt% (two-stage process) to 8 wt% (multistage process).

Predicting the impacts of Mississippi River diversions and sea-level rise on spatial patterns of eastern oyster growth rate and production

There remains much debate regarding the perceived tradeoffs of using freshwater and sediment diversions for coastal restoration in terms of balancing the need for wetland restoration versus preserving eastern oyster (Crassostrea virginica) production. Further complicating the issue, climate change-induced sea-level rise (SLR) and land subsidence are also expected to affect estuarine water quality. In this study, we developed a process-based numerical modeling system that couples hydrodynamic, water quality, and oyster population dynamics. We selected Breton Sound Estuary (BSE) (∼2740km2) in the eastern Mississippi River Deltaic Plain since it is home to several of the largest public oyster seed grounds and private leases for the Gulf coast. The coupled oyster population model was calibrated and validated against field observed oyster growth data. We predicted the responses of oyster population in BSE to small- (142m3s−1) and large-scale (7080m3s−1) river diversions at the Caernarvon Freshwater Diversion structure planned in the 2012 Coastal Master Plan (Louisiana) under low (0.38m) and high (1.44m) relative sea-level rise (RSLR=eustatic SLR+subsidence) compared to a baseline condition (Year 2009). Model results showed that the large-scale diversion had a stronger negative impact on oyster population dynamics via freshening of the entire estuary, resulting in reduced oyster growth rate and production than RSLR. Under the large-scale diversion, areas with optimal oyster growth rates (>15mg ash-free dry weight (AFDW) oyster−1wk−1) and production (>500g AFDWm−2yr−1) would shift seaward to the southeastern edge of the estuary, turning the estuary into a very low oyster production system. RSLR however played a greater role than the small-scale diversion on the magnitude and spatial pattern of oyster growth rate and production. RSLR would result in an overall estuary-wide decrease in oyster growth rate and production as a consequence of decreased salinities in the middle and lower estuary because rising sea level likely causes increased stage and overbank flow downstream along the lower Mississippi River.

Marine periphyton biofilters in mariculture effluents: Nutrient uptake and biomass development

Cost of effluent treatment, water quality maintenance and feeds constitute most of aquaculture's operational costs, and influence its sustainability. The present study examined the effectiveness of periphyton for biofiltration of mariculture effluents. Marine periphyton was allowed to spontaneously develop on a plastic net substrate, in experimental bioreactors that were fed with effluents from fish mariculture ponds. Biomass development and nutrient uptake were followed over four seasons. Attention was given to the orientation and area of the net substrate, season and additional operational factors. The highest specific growth rate (SGR) of 27% day−1 was measured during the second week of periphyton growth in the summer. Mean daily periphyton production rates in the spring and autumn were 2.4 and 1.8g (ash-free dry weight) m−2day−1, respectively. The vertical orientation of the net substrate was overall advantageous over the horizontal orientation. Increasing the substrate area of vertically oriented nets in the biofilter increased the removal efficiency of total ammonia nitrogen (TAN) up to 80%, and allowed more biomass production in the biofilter. Multiple polynomial regression models suggest strong effect of biomass weight and effluent retention time on the removal efficiency of TAN and dissolved inorganic nitrogen (DIN). The removal rates of TAN and DIN in these experiments were between 0.11 and 1.2gNm−2 (substrate area) day−1 for periphyton at the age of 7 and 42days, respectively. Marine periphyton seems to be a simple, low cost and sustainable component, which can perform biofiltration/rehabilitation of water quality and potentially serve as feed for fish and shrimp.

Macroalgae culture to treat anaerobic digestion piggery effluent (ADPE)

Environmental consequences of high productivity piggeries are significant and can result in negative environmental impacts, hence bioremediation techniques (in particular using macroalgae) are therefore of great interest. Here, the growth potential of several freshwater macroalgae in anaerobic digestion piggery effluent (ADPE), their nutrient removal rates and biochemical composition of the biomass were investigated under outdoor climatic conditions. A consortium of two macroalgae, Rhizoclonium sp. and Ulothrix sp. was isolated and could efficiently grow in the ADPE. Maximum ammonium removal rate (30.6±6.50mg NH4+-NL−1d−1) was achieved at ADPE concentration equivalent to 248mgNH4+-NL−1. Mean biomass productivity of 31.1±1.14g ash-free dry weight (AFDW) m−2d−1 was achieved. Total carbohydrate and protein contents ranged between 42.8–54.8 and 43.4–45.0% AFDW, respectively, while total lipid content was very low. The study indicates the potential use of this macroalgal consortium for treating ADPE as well as source of animal feed production.

Simulation of outdoor pond cultures using indoor LED-lighted and temperature-controlled raceway ponds and Phenometrics photobioreactors

Two innovative culturing systems, the LED-lighted and temperature-controlled 800 liter indoor raceways at Pacific Northwest National Laboratory (PNNL) and the Phenometrics environmental Photobioreactors™ (ePBRs) were evaluated in terms of their ability to accurately simulate the microalgae growth performance of outdoor cultures subjected to fluctuating sunlight and water temperature conditions. When repeating a 60-day outdoor pond culture experiment (batch and semi-continuous at two dilution rates) conducted in Arizona with the freshwater strain Chlorella sorokiniana DOE 1412 in these two indoor simulators, it was found that ash-free dry weight based biomass growth and productivity in the PNNL climate-simulation ponds was comparatively slightly higher (8–13%) but significantly lower (44%) in the ePBRs. The difference in biomass productivities between the indoor and outdoor ponds was not statistically significant. When the marine Picochlorum soloecismus was cultured in five replicate ePBRs at Los Alamos National Laboratory (LANL) and in duplicate indoor climate-simulation ponds at PNNL, using the same inoculum, medium, culture depth, and light and temperature scripts, the optical density based biomass productivity and the rate of increase in cell counts in the ePBRs was about 35% and 66%, respectively, lower compared than in the indoor ponds. Potential reasons for the divergence in growth performance in these pond simulators, relative to outdoor raceways, are discussed. In conclusion, the PNNL climate-simulation ponds provide reasonably reliable biomass productivity estimates for microalgae strains cultured in outdoor raceways under different climatic conditions.

Algae-based biofilm productivity utilizing dairy wastewater: effects of temperature and organic carbon concentration.

BackgroundBiofilm-based microalgal growth was determined as functions of organic chemical loading and water temperature utilizing dairy wastewater from a full-scale dairy farm. The dairy industry is a significant source of wastewater worldwide that could provide an inexpensive and nutrient rich feedstock for the cultivation of algae biomass for use in downstream processing of animal feed and aquaculture applications. Algal biomass was cultivated using a Rotating Algal Biofilm Reactor (RABR) system. The RABR is a biofilm-based technology that has been designed and used to remediate municipal wastewater and was applied to treat dairy wastewater through nutrient uptake, and simultaneously provide biomass for the production of renewable bioproducts.ResultsAerial algal biofilm growth rates in dairy wastewater at 7 and 27 °C temperatures were shown to be 4.55 ± 0.17 g/m2-day and 7.57 ± 1.12 g/m2-day ash free dry weight (AFDW), respectively. Analysis of Variance (ANOVA) calculations indicated that both an increase in temperature of the wastewater and an increase in the level of organic carbon, from 300 to 1200 mg L-1, contributed significantly to an increase in the rate of biomass growth in the system. However, ANOVA results indicated that the interaction of temperature and organic carbon content was not significantly related to the biofilm-based growth rate.ConclusionA microalgae-based biofilm reactor was successfully used to treat turbid dairy wastewater. Temperature and organic carbon concentration had a statistically significant effect on algae-based biofilm productivity and treatment of dairy wastewater. The relationships between temperature, TOC, and productivity developed in this study may be used in the design and assessment of wastewater remediation systems and biomass production systems utilizing algae-based biofilm reactors for treating dairy wastes.

Recycling Nannochloropsis oceanica culture media and growth inhibitors characterization

The sequential recycling of culture medium that had different initial nitrogen concentrations and was treated with an ultrafiltration membrane was investigated to determine the effects of recycled media on the growth of Nannochloropsis oceanica. Algae growth and lipid accumulation were inhibited by the recycled media. The final average ash-free dry weight (AFDW) values of N. oceanica after 12days of cultivation in the recycled media at initial nitrogen concentrations of 64 and 32mgL−1 were 2.3 and 1.6gL−1, respectively, and these values were 14.8% and 23.8% lower than those of the AFDW of N. oceanica cultured in fresh media (2.7 and 2.1gL−1, respectively). The total lipid contents of the algae cultured in the recycled media for 12days (37.2±2.9% and 39.7±4.3%, at initial nitrogen concentrations of 64 and 32mgL−1, respectively) were lower than those of the algae cultivated in the fresh media (43.7±3.3% and 47.2±1.2%, respectively). A greater number of cell aggregates were observed in the recycled media culture at low initial nitrogen concentrations than in the fresh media. The removal of potential growth inhibitors in the recycled media by activated carbon resulted in a moderate increase in the AFDW and total lipid content. The recycled media were characterized using Fluorescence Excitation-Emission Matrix (FEEM), Fourier Transform Infrared (FTIR) and size-exclusion HPLC analyses, and the results indicated that polysaccharides humic acid-like and fulvic acid-like substances occurred in the recycled media and likely caused the growth inhibition. Further studies are necessary to confirm the inhibitory effects of these components, explore the mechanisms of inhibition, and identify more efficient methods of removing growth inhibitors from recycled culture media.

One-pot bioconversion of algae biomass into terpenes for advanced biofuels and bioproducts

Under robust algae growth conditions, algal carbohydrates and proteins typically comprise up to ~80% of the ash-free dry weight of microalgae biomass. Therefore, production of algal biofuel through comprehensive utilization of all algal components and the addition of high energy density fuel compounds with “fit for purpose” properties or high-value bioproducts will both diminish the process cost and improve the overall process feasibility. In this study, we firstly demonstrated the concept of a “one-pot” bioconversion of algal carbohydrate and protein into value-added terpene compounds as advanced biofuel and high value bioproducts to improve the overall process feasibility through the development of engineered microbial consortium. The consortium for caryophyllene production yielded the highest titer of total terpene, up to 507.4mg/L, including 471mg/L of sesquiterpene, 36.4mg/L of monoterpene, and 124.4mg/L of caryophyllene on algal hydrolysate from Nannochloropsis sp. Additionally, the consortium expressing chamigrene synthase produced 187mg/L total terpene including 87mg/L of monoterpene, 100mg/L of sesquiterpene, and 62mg/L chamigrene on hydrolysate from benthic polyculture biomass. Compared to the yields of terpene extracted from plant tissue, both consortia increased the terpene yield about 3–40 times, which makes it a promising alternative pathway for terpene production.

Relationships between fresh weight, dry weight, ash free dry weight, carbon and nitrogen content for selected vertebrates

Top predators are relevant indicators of the ecological status of a system and can have a high impact on food webs. But top predators are difficult to include in network analyses because their biomass in ash free dry weight or carbon content is missing. Regression equations were determined for the relationships between fresh weight and dry weight, ash free dry weight, carbon and nitrogen contents respectively for six of the most abundant bird species in the Wadden Sea (Calidris canutus, Limosa lapponica, Haematopus ostralegus, Chroicocephalus ridibundus, Larus canus, Anas penelope) and harbor seals (Phoca vitulina). The relationships for all species were interpreted as linear through the origin. Carbon content vs. fresh weight ratios for birds ranged from 0.16±0.01 to 0.22±0.02. Carbon content vs. fresh weight ratio was 0.17±0.02 on average for harbor seals. This work highlights that the biomass of top predators was often over- or underestimated in previous studies. The determined conversion factors will be useful for future studies to generate more realistic food web models.

Simultaneous production assessment of triacylglycerols for biodiesel and exopolysaccharides as valuable co-products in Navicula cincta

The marine benthic diatom Navicula cincta was cultured in order to evaluate its capacity to produce both neutral lipid-triacylglycerols (TAG) for biodiesel, and exopolysaccharides (EPS), as valuable co-products, under the same environmental conditions. The species was cultured without applying stress conditions, except for the ones naturally created by the culture age. Peaks of neutral lipid accumulation were estimated by fluorimetry by Nile Red. Consequently, lipids were extracted and fractionated into neutral and polar fractions and the fatty acid profile of each fraction analysed by GC. The stationary phase began on day 6, when phosphate and silicate reached limiting values for diatom growth. Total lipids and lipid fractions did not show differences between harvesting time points, reaching total lipid up to 41% of ash-free dry weight (AFDW) and TAG the dominant fraction (ca. 90% of total lipids). Particularly noticeable was the storage of palmitoleic acid (ca. 54% of total fatty acid methyl esters) and a lower level of polyunsaturated fatty acids, which may impart overall favourable properties to a biodiesel fuel, especially cold flow and oxidative stability. The maximum concentrations of EPS corresponded to soluble fraction, which was most significant when the cultures reached the stationary phase and when the medium was almost phosphate and silicate depleted. The characterization of soluble EPS indicated the presence of N-glycopeptides. According to the present results, a hypothetical scheme of demonstrative cultures under a biorefinery approach is proposed for N. cincta.

Oil assessment of Halamphora coffeaeformis diatom growing in a hybrid two-stage system for biodiesel production

The lipid content, composition and productivity of the marine benthic diatom Halamphora coffeaeformis were studied in order to evaluate its potential as feedstock for biodiesel production. Cultures were carried out in two stages: I) in photobioreactors (PBRs) to increase the biomass as inoculum for larger volumes, and II) in raceway ponds to increase naturally the triacylglycerol (TAG) content during the stationary growth phase. Biomass concentrations of 0.64 g L−1 and 0.23 g L−1 were reached in the PBR and the raceway pond, respectively. Total lipid content was 54.4 (±11.6) % ash free dry weight (AFDW) in the raceway pond on day 19 (harvest day), with a neutral lipid content of 34% AFDW. The TAG productivity in the raceway pond was 1.2 mg L−1 d−1. The indicators of biodiesel, calculated from fatty acid profile composition, showed that H. coffeaeformis oil was of good quality, according to international standards. Some hypothetical aspects are proposed in order to improve lipid productivity and net energy ratio in processes at larger scales.

Evaluation of Growth and Survival of Artemia franciscana fed with Nannochloropsis oculata and Chlorella capsulata

Artemia franciscana was fed for seven days with 11.7, 23.4 and 46.8 mg l-1. d-1 (ash-free dry weight) of Nannochloropsis oculata and Chlorella capsulata, to evaluate the food value of these two microalgae. Survival was similar, close to or greater than 90% in all cases, but there were significant differences in growth beginning on the third day. The final ash-free dry weight of A. franciscana fed with N. oculata was seven times greater than with C. capsulata and the respective developmental stages were between instar 14 and 16 and from 8 to 9. Food ingestion was similar with the two diets, but the mean gross growth efficiencies were 80% with N. oculata and 7% with C. capsulata, indicating a poor assimilation of C. capsulata. Therefore, C. capsulata cannot be considered as a suitable diet for A. franciscana, because the amount of energy obtained is not sufficient to sustain normal growth.International Journal of Life Sciences 10 (1) : 2016; 35-39

The role of Mediterranean sponges in benthic–pelagic coupling processes: Aplysina aerophoba and Axinella polypoides case studies

Sponges are important components of marine benthic communities with a worldwide distribution ranging from polar to tropical regions. They play a key role in benthic–pelagic coupling processes through their active suspension feeding, providing a trophic link between the benthos and the overlying water column. Little is known about their broad-scale distribution and feeding ecology. The general tendency is to quantify their trophic impact through small patch estimations. In this work, two of the most abundant sponges in Mediterranean coastal bottoms (Aplysina aerophoba and Axinella polypoides) were studied combining remotely operated vehicle (ROV) survey with in situ feeding experiments. Spatial, bathymetrical distribution and population size structure of these species were analysed, together with their trophic ecology, in spring and autumn. We found that A. aerophoba is distributed between 5 and 20m depth, with maximum densities of 1.6 sponges m−2. This species ingested 0.12–0.39mg of carbon (C)gAFDW−1 (ash free dry weight) day−1 in spring and 0.09–0.13mgCgAFDW−1day−1 in autumn. Conversely, A. polypoides was found between 10 and 70m depth, with maximum densities of 7.6 sponges m−2. This species ingested 0.07–0.17mgCgAFDW−1day−1 in spring, and 0.18–0.60mgCgAFDW−1day−1 in autumn. The highest uptake of C concentrated between 5 and 15m depth for A. aerophoba and between 65 and 70m depth for A. polypoides. In the 1.14ha of studied coastal bottom, A. aerophoba ingested 1.87gC during spring and 0.19gC during autumn, whereas A. polypoides 13.60gC and 29.36gC during spring and autumn, respectively. The present approach allowed a spatially explicit quantification of benthic–pelagic coupling processes produced by two of the most common sponges in a Mediterranean coastal area. This methodology, applied to benthic communities, mirrors similar approaches used in terrestrial forestry studies for C flux estimation.

Fluvial biofilm responses to joint changes in nutrients, temperature, turbidity and water velocity: an ex situ experiment

The aim of this study was to explore the responses of the epipelic biofilm of a Pampean stream with little impact from human activity to two environmental conditions, with joint modifications in nutrients, temperature, water velocity and turbidity. The experiment was conducted using artificial channels and lasted five weeks. The biological variables measured included chlorophyll-a content, bacterial biomass, ash-free dry weight, total carbohydrate concentration, total respiratory activity, and biofilm composition. Results show that the species’ composition of the biofilm was affected, although no other structural or metabolic variables measured were. These results highlight the importance of including structural parameters to measure rapid changes in water quality, even when analyzing the effects of co-occurring variables.

Comparison of Different Methods to Assess Macrobenthic Biomass within an Anti-Estuarine Zostera Marina Meadow in Baja California, Mexico

Biomass is a fundamental variable to estimate benthic secondary production. Currently, the loss-on-ignition (LOI) technique is the most used method for biomass assessment, although it is expensive, time consuming, and subject to error due to the volatilization of the samples in the muffle. Moreover, samples are lost for subsequent taxonomic identification. Alternative methods for biomass evaluation, such as conversion factors, are fast, easy, reliable, and the samples are preserved for species identification. In the present study, we took benthic macrofauna samples at bimonthly intervals from August 2009 to May 2011 in a Zostera marina meadow at Estero Punta Banda, Mexico. We compared biomass estimations of the main benthic taxa between the LOI method and five conversion factors. The total mean biomass assessed with the LOI method was 45.14 ± 13.56 g ash-free dry weight (AFDW) m−2, while the values of the alternative estimation methods ranged from 63.12 ± 13.56 g AFDW m−2 to 39.25 ± 9.35 g AFDW m−2. There were no significant differences among mean biomass values estimated with the different methods (two way ANOVA, p = 0.49), indicating that all methods are valuable alternatives. The two conversion factors showing the highest correlation with the LOI method were chosen as the most reliable alternatives to estimate biomass (BREY and R&B).