The sea cucumber
Holothuria inornata
is a species whose populations are at risk. This study aims to investigate its reproduction, embryonic and larval development, and the settlement of
H. inornata
...under an algae-based diet. Twenty breeders were utilized, which underwent a 1.5-h desiccation followed by a thermal shock (27 to 32 °C). Embryonic development stage was recorded, and from the auricularia larval stage, three treatments were evaluated: A:
Chaetoceros muelleri
and
Isochrysis galbana
(1:1 ratio); B:
C. muelleri
,
I. galbana
,
Tetraselmis suecica
, and
Pavlova lutheri
(1:1:1:1 ratio); and C:
Chaetoceros muelleri
,
I. galbana
,
T. suecica
,
P. lutheri
,
Navicula
sp. (LPU-6) (1:1:1:1:1 ratio), with a larval density of 100 larvae L
−1
in triplicate.
The embryonic development in
H. inornata
lasts for 3 days, five larval stages were recorded: (1) Auricularia (days 3–8, 300 to 520 μm), (2) late auricularia (days 8–11, 520 to 670 μm), (3) doliolaria (days 11–13, 460 to 550 μm), (4) late doliolaria (days 13–16, 400 to 440 μm), and (5) pentacula (days 15–19, 650 to 900 μm). The post-settlement survival rate was 0% under treatment A, 2.38 ± 0.16% under treatment B, and 3.79 ± 0.41% under treatment C. Based on these findings, we concluded that
H. inornata
specie spawn through a combined desiccation-thermal shock process with a larval period of up to 19 days, and subsequently produce juvenile individuals in captivity with a varied microalgae diet.
In this study, five microalgal strains were isolated from Bahía de La Paz, Baja California Sur, Mexico and identified as Grammatophora sp., Navícula sp., Rhabdonema sp., Schizochytrium sp., and ...Nitzschia sp., and their evaluation as potential food for Artemia franciscana. The isolated strains were cultured outdoors and harvested after four days. Chaetoceros muelleri was cultured under laboratory conditions and used as control. The protein, lipid, and carbohydrate composition and the fatty acid profiles of the strains were determined by gas chromatography. To assess the effect of microalgal strains on A. franciscana, decapsulated cysts were cultured at outdoor conditions in 15 L containers. The experiment was conducted for twelve days. Samples from the five different feeding treatments were taken at the beginning and end of the experiment to assess number, size, and weight of Artemia larvae. Treatment with Rhabdonema sp. showed larvae with a lower percentage of polyunsaturated fatty acids (PUFAs) while Grammatophora sp. showed those with the greatest PUFA proportion, even more than those fed Chaetoceros muelleri (control). Larvae consuming Schizochytrium sp. had no docosahexanoic (DHA) nor eicosapentaenoic (EPA) fatty acid content. Growth and survival of A. franciscana did not show significant differences among feed treatments, except when it was fed Nitzschia sp., showing lower survival and dry weight. Treatment based on Schizochytrium sp. and Rhabdonema sp. had a greater A. franciscana size but reduced dry weight; additional tests including two or more algal species for every treatment should be carried out to determine the best yield.
Biofloc systems in Pacific white shrimp (Penaeus vannamei) culture generate floccules that remove wastes, and hence, biofloc formation is promoted for shrimp production. This study evaluated the ...induction of biofloc formation using microalgae and probiotic bacteria in hyper-intensive Pacific white shrimp culture. The experiment was performed for six weeks in tanks (28,000 L each) stocked 350 ind m-3 and weight of 1400 ± 30 mg. Three treatments were assessed: 1) with two diatoms: Grammatophora sp. and Navicula sp., 2) with Navicula sp., and 3) without diatoms. All treatments were added with Schizochytrium sp. and Lactobacillus fermentum TD19. The following parameters were monitored during culture: ammonium, nitrites, nitrates, environmental variables, floccules volume, microorganism presence, the bromatological composition of biofloc, and growth performance parameters of P. vannamei. Our results indicated that the three induced biofloc presented a similar volume (8.34 ± 4.8 mL L-1) and ammonium concentration (<1.0 mg L-1). Treatment 1 generated floccules with the highest concentration of ciliates, rotifers, nematodes, lactic acid bacteria, and the lowest concentration of Vibrio spp. (1.2×103 UFC mL-1), evidencing a significant difference in bromatological composition, with the highest protein and lipid values (28.12 ± 0.50 and 22.44 ± 0.80% biofloc dry weight, respectively) and the best feed conversion ratio (0.89). Based on these results, we suggest that Schizochytrium sp., L. fermentum, and two diatoms should be used to induce biofloc in a hyper-intensive culture of P. vannmaei in order to provide a supplementary nutritional intake, which can constitute an advantage to reduce commercial feed rations.
•Schizochytrium sp. associated with Lactobacillus plantarum (T19 bacilli strain) can be an inoculum for starting biofloc systems for cultures of L. vannamei.•Schizochytrium sp. associated with ...Lactobacillus plantarum (T19 bacilli strain) prevents the growth of Vibrio spp. in biofloc systems for cultures of L. vannamei.•Schizochytrium sp. and Lactobacillus plantarum (T19 bacilli strain) can reduce shrimp diseases and environmental impact.
At present, the Pacific white shrimp Litopenaeus vannamei Boone, 1931, is one of the species with the greatest potential to be reared under biofloc Technology (BFT). Although BFT presents promising culture methods, some of these require improvements in efficiency by the use of native microalgae and bacteria (BFNO) as an alternative to commercial organism probiotics (BFCO). This experiment was developed using a culture system for the shrimp L. vannamei to a stocking density of 400 in./m3 for 44 days. Schizochytrium sp. and recently isolated Latobacillus plantarum (class: Bacilli), a probiotic strain (used as experimental biofloc), were incorporated to geomembrane tanks holding 28 m3 seawater to evaluate if these presented bioregulating effects influencing water quality and growth performance of L. vannamei. These microorganisms were compared with the BFCO. Results showed that both promoted bioflocs maintained optimal concentrations of total ammonium, nitrites, and nitrates for L. vannamei cultures. However, the BFCO required to be supplied every 10 days, whereas the experimental biofloc only required an initial stocking and maintenance of sodium carbonate levels >100 mg L−1 and pH > 7.5. Additionally, the load of Vibrio spp. in experimental biofloc was less than that observed for BFCO. Furthermore, the results of growth performance did not demonstrate differences between both treatments. Therefore, it is suggested that Schizochytrium sp. and the bacterial strain of L. plantarum should be used as initiator and basic constituents of the biofloc-based culture systems for L. vannamei, maintaining good water quality and avoiding periodical probiotic supplementation in cultures.
The ionic composition of culture water may be a more important limiting factor than the salinity itself and may lead to osmotic stress which may influence growth and survival of shrimp culture. The ...uptake rate and the effect of magnesium chloride (MgCl
2
), calcium chloride (CaCl
2
), and potassium chloride (KCl) salts in juveniles of whiteleg shrimp (
Litopenaeus vannamei
) cultured with biofloc technology (BFT) was evaluated for 62 days in seawater (30 practical salinity unity). Five treatments were analyzed in triplicate: T1; control (water exchange rate of 5% daily), T2; adding CaCl
2
+ MgCl
2
+ KCl, T3; adding MgCl
2
+ KCl, T4; adding CaCl
2
+ KCl, and T5; adding CaCl
2
+ MgCl
2
. Mineral salts were added to water and the response of experimental parameters: physicochemical variables of water quality, osmotic pressure, total hemocyte count, glutathione peroxidase gene expression, superoxide dismutase, and zootechnical variables of the shrimp was assessed. The uptake of single chloride salts (CaCl
2
, MgCl
2
, and KCl) by shrimp varied as a function of the concentrations and the ratio of these three ions. Magnesium deficiencies in the culture medium increased CaCl
2
and KCl uptake without showing gene expression of SOD and GPx. The best survival rate was obtained by adding the three ions (T2) and the control (T1, water exchange of 5%). We concluded that
L. vannamei
can be maintained by the addition of essential chloride ions in BFT without water replacement.
Sea cucumbers (holothuroids) play a major role in coastal environments; their detritivore conduct favors oxygen penetration in the sediments and the disposal of pathogens on the sea floor. This study ...determined holothuroid diversity in the rocky intertidal zone of Matanchen Bay, Mexico. Sampling campaigns were carried out in January, March, May, and July 2018. Linear transects (10 m length and 1 m width) perpendicular to the coastline in rocky areas (0-3 m depth) were established, where the density (ind m.sup.-2) and proportion (%) of sea cucumbers were estimated. Organisms were photographed, examined live, and preserved in 70% alcohol for subsequent identification utilizing ossicle characterization. Our results show the presence of four sea cucumber species: Holothuria (Halodeima) inornata Semper, 1868, Holothuria (Selenkothuria) lubrica Selenka, 1867, Holothuria (Selenkothuria) portovallartensis Caso, 1954, and Holothuria (Mertensiothuria) viridiaurantia Borrero-Perez & Vanegas-Gonzalez, 2019. The average density per species was 0.208, 0.108, 0.017, and 0.025 ind m.sup.-2, respectively; each species' proportion was 58.1, 30.2, 4.7, and 7.0%, respectively. Due to the above values, we found that the number and spatial distribution of sea cucumber species vary in Matanchen Bay.
The state of Nayarit is the main oyster producer in the Mexican Pacific, this derived from artisanal crops of Crassostrea corteziensis and collecting of wild seeds. Despite its importance, there are ...no studies on the reproduction of this species in Boca de Camichin, Nayarit, Mexico, which is the area with the highest production (around 90%). The aim of this study was to evaluate sex ratio, condition index (CI), reproductive cycle, and recruitment size for reproduction and its relationship with environmental factors. Sixty oysters were sampled monthly at La Palicienta Lagoon for one year. The organisms were weighed and measured, then fixed with 10% formalin for histological analyses. Subsequently, the gonads were processed by histology. Sex ratio was different from 1:1, with a predominance of females. The condition index (CI) was higher from March to July. Oyster spawning was most prevalent in May, August, and October. The temperature had a positive relationship with reproduction. Recruitment size at reproduction was 57.1 mm. The results of this study could supply useful information about reproduction of the species at La Palicienta and seed collection in Boca de Camichin, Nayarit.
The in vitro digestibility of lipids from
Chaetoceros muelleri
that were cultured in Guillard medium (F/2) and agricultural fertilizer medium (AF/2) and performance index was examined in enzymatic ...extracts of
Litopenaeus vannamei
larvae. The highest enzymatic activity (EA) of lipases was observed in Zoea I (1.53 ± 0.14 EA/10 EU) and Mysis I (1.26 ± 0.01 EA/10 EU (EU are units of enzymatic activity)) when
C. muelleri
was grown in the F/2 medium. The highest concentration of the unsaturated fatty acids (UFAs) in
C. muelleri
was observed with F/2 medium (9.96 μg FA/10
6
cells), and the lowest was obtained with (AF/2) medium (6.68 μg FA/10
6
cells). The percentage of the total highly unsaturated fatty acids (HUFAs) in Zoea (18.23 %) and Mysis I (F/2 = 19.32 %, AF/2 = 20.25 %) larvae was similar between culture media. The performance indices (PI) of shrimp larvae (Zoea I to Mysis I) differed between culture media, with higher values of PI recorded with the F/2 medium-cultured algae (14.3 ± 1.1) with respect to the values with the AF/2 medium-cultured algae (8.0 ± 1.8). We concluded that due to the effect of the nitrogen source in AF/2 medium,
C. muelleri
cells have a lower HUFA content and
L. vannamei
larvae experience decreased lipid digestibility and performance index.
The aim of this work was to demonstrate that the source of nitrogen of microalgae growth media has an effect on the biochemical composition by comparing the composition of Chaetoceros muelleri grown ...in semicontinuous cultures with 30% daily dilutions with an agricultural fertilizer containing three nitrogen sources (AF) and with the traditional f/2 medium. The cell yields, proximate composition, and total essential and nonessential amino acid contents of C. muelleri were similar, but phenylalanine and glutamate were significantly higher with f/2, and alanine was higher with AF. Monounsaturated fatty acids were higher in AF-grown cultures, but polyunsaturates were higher with f/2. Among polyunsaturates, 20:5n-3 (eicosapentaenoic acid, EPA) was higher with AF (17.16%) than with f/2 (13.44%), whereas f/2 yielded cells richer in 20:4n-6 (arachidonic acid, ARA: 2.08% vs. 1.38%) and 22:6n-3 (docosahexaenoic acid, DHA: 6.86% vs. 3.80%). Our results provide evidence that different nitrogen sources may cause variations in the biochemical profile of C. muelleri.
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