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Abstract

The effect of different salinities on growth, crude protein and total energy on a Mexican strain of the minute rotifer Proales similis (GenBank KM078762) were evaluated. The experiment was conducted at 5, 15, 25 and 35 psu, with five replicates. Rotifers were fed twice a day with Nannochloropsis sp., temperature, dissolved oxygen and pH values were maintained at 25±1°C, 5±1 mg L -1 and 8±1 respectively. Results show that salinity does not affect the intrinsic rate of population growth (r=0.46 to 0.51 day -1 ) and duplication time (Dt=1.36 to 1.51 days) for P. similis. Maximum density (Dmax) values were lower at 35 psu (1,703 rotifers ml -1 ), whereas Dmax values were between 2,488 to 2,560 rotifers ml -1 at 5, 15 and 25 psu. Crude protein fluctuated between 25.3 and 42.8% dry biomass (DB), while energy content varied between 11.8 and 19.9 J mg -1 DB; values were significantly lower at 35 psu. Observed population growth parameters and the protein and energy content between 5-25 psu, indicate that P. similis can be successfully reared below 35 psu, making P. similis very suitable when fish larvae require a small rotifer due to sizing of mouth gap at the beginning of exogenous feeding.

Availability of the euryhaline rotifer Proales similis as prey after rapid salinity transfer

“…(2-35 ppt), making it an ideal candidate for a broad spectrum of fish species with high aquaculture potential (Rebolledo et al, 2021;Román-Reyes et al, 2017;Wullur et al, 2009). Such fish families list includes Atherinidae, Lutjanidae, Serranidae, Chanidae, Sparidae, Sciaenidae, Percidae, Latidae, Mugilidae, Siganidae, Scatophagidae, among others whose feeding protocols involve rotifers (Imentai et al, 2019;Kailasam et al, 2015;Labatut & Olivares, 2004;Martıńez-Palacios et al, 2004;Wullur et al, 2011).…”

“…The monogonont rotifer P. similis was isolated from resting eggs in the sediment of a shrimp farm (23°09′10.54″N, 106°18′22.84″W) in the northwest Mexico (Román-Reyes et al, 2017). Since then, it has been maintained under laboratory conditions.…”

“…In our laboratory, P. similis is cultured at 15-25 ppt and 25-30°C under natural light. The brackish water is obtained by diluting seawater (Mazatlan Bay, Mex) with freshwater taken from the drinking water network, previously treated as described in Román-Reyes et al (2017). This Mexican strain of P. similis feeds exclusively on the marine microalgae Nannochloropsis sp.…”

“…Proales similis is a euryhaline rotifer found in inland saline waters and marine environments (Román-Reyes et al, 2017;Walsh et al, 2008;Wullur et al, 2009). This species has been isolated for experimental purposes (aquaculture and ecotoxicology) in Japan and Mexico (Rebolledo et al, 2021;Rebolledo, Nandini, Escobar-Sánchez, & Sarma, 2018;Wullur et al, 2009).…”

“…Unlike B. plicatilis, P. similis lacks a lorica rich in scleroproteins; therefore, it has a flexible body that could facilitate its consumption and ingestion by the larvae (Wullur et al, 2011). It is known that P. similis achieves high growth rates at 2-25 ppt and temperatures above 25°C (Román-Reyes et al, 2017;Wullur et al, 2009). Extrapolating the results of laboratorybased studies, it can reach high densities in massive cultures such as B. plicatilis (Lubzens et al, 2001).…”