Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

It has been established that cryptic fish (CF) contribute to keeping the equilibrium of marine environments, and are also potential indicators of the environment. In the present study, ecological evaluations of CF-associated with reef communities exposed to high or low anthropogenic pressure off the coast of Colima, Mexico (La Boquita-LB, and Carrizales Bay-CA, respectively) were carried out. During 2014 a total of 16 surveys were carried out during winter-spring (WS), and eight surveys were carried out in summer-fall (SF). Three CF surveys were carried out in each reef community, covering a 180 m2 area; several ecological indices were calculated, and the benthic habitat was characterized. A total of 3,056 CF belonging to 23 species, 22 genera, and 15 families were recorded. The species Axoclinus lucillae, Acanthemblemaria macrospilus, Coralliozetus boehlkei, Ekemblemaria myersi, and Hippocampus ingens represented new records for CA and LB. The physiographic and topographic characteristics of the marine substrate were factors that significantly influenced the occurrence of CF, especially those with reduced mobility. There was higher CF richness and diversity during the SF. The species A. macrospilus, C. boehlkei, and E. myersi, associated with rocky environments with high sponge and macroalgae cover, were identified as potential bioindicators of degradation of the benthic habitat. The species Cirrhitichtys oxycechalus, A. macrospilus, Coryphopterus urospilus, and Elacatinus punticulatus were associated with coralline, crystalline, and relatively unperturbed environments.

Cittarium pica is an endangered Caribbean gastropod of ecological and economic importance. In order to provide the basis for the aquaculture development and/or population management of this species, the relationships among its body size and physiological variables associated with the energetic balance were assessed. Individual measurements of rates of egestion (ER), ingestion (IR), absorption (AR), oxygen consumption (OCR), ammonia excretion (UR), mucus production (MR), absorption efficiency (AE) and scope for growth (SFG), were carried out on specimens between 0.01 and 12.07 g of dry weight of the soft parts (DW) under controlled laboratory conditions. Most of the variables showed positive potential relationships with the DW of the animals (ER mg h-1 = 1.51 DW0.37, IR mg h-1 = 4.13 DW0.32, AR = 2.56 DW0.30, OCR mL O2 h-1 = 0.38 DW0.74, UR μg NH4 -N h-1 = 19.17 DW0.78, MR mg h-1 = 1.28 DW0.14 and SFG = 36.92 DW0.22). AE did not show any relationship with this variable. The large snails had faster input and output of energy compared to the small specimens, also having proportionally greater energetic expenditures, mucus production, and energetic balance.

This study reports the first record of a white shark Carcharodon carcharias off the tropical coast of Nayarit and the southernmost record in the Mexican Pacific. The specimen was a juvenile female accidentally caught by artisanal fisheries in the locality of Playa Novillero, Nayarit. Oceanographic conditions at the time of capture were also recorded, with the aim of improving the knowledge on the ecology of this vulnerable and protected species.

The ascidian fauna of northern Chile (18º to 25ºS) is poorly known. A member of the family Ascidiidae, Ascidia ceratodes (Huntsman, 1912), is reported in this study. We collected samples of A. ceratodes under intertidal boulders off the northern Chilean coast between Arica (18°S) and Iquique (20°S) (17 to 20°C; intertidal pool; <0.5 m depth; August, 2016). This finding verified a questionable record established by Van Name (1945) from Tocopilla (22ºS), northern Chile. This record extends the confirmed geographical distribution of A. ceratodes along of the eastern Pacific coast from British Columbia, Canada, to northern Chile.

The use of water temperature to modify sex proportion in Nile tilapia has been suggested as an alternative to eliminating the use of steroids since it was discovered that it has an important role in the sex differentiation process. However, the use of cold-water temperatures to achieve feminization has rarely been explored and never has it been combined with exogenous estrogens. This work aimed to determine if the proportion of females could be increased by combining low concentrations of estrogens with a cold-water temperature, and describing its effect on growth parameters, gonadosomatic index, and fat muscle content. Two experiments were carried out, each one set at a specific water temperature (27.5 and 21.5ºC). In each experiment four treatments (per triplicate) were evaluated (control -no estrogens-, estradiol-17β E2, 17α-ethinylestradiol EE2 and diethylstilbestrol DES). Higher feminization rates were observed in all groups, including the control group, reared at 21.5ºC. Growth parameters showed significantly higher values (P < 0.05) for the groups reared at 27.5ºC. The control group and the group fed E2 reared at 21.5ºC showed significantly higher (P < 0.05) values of gonadosomatic index than that observed in the groups reared at 27.5ºC. Fat muscle content was significantly higher (P < 0.05) in both experiments for the groups fed E2 and EE2. The fry used showed a high tendency towards feminization by exposure to a cold-water temperature. Our results allow us to consider E2 (21.5ºC) the best option for the development of YY technology.

Trichodiniasis is one of the major diseases found in fish aquaculture worldwide causing massive fish mortality and costly effects. In this study, fresh smears of gills and skin were prepared and analyzed for the presence of trichodinids under light microscopy, revealing the presence of Trichodina pediculus Ehrenberg, 1831, T. compacta Van As & Basson, 1989, and T. nigra Lom, 1960 and T. centrostrigeata (Basson, Van As & Paperna, 1983). The effectiveness of treatment with sodium chloride and formaldehyde was evaluated for controlling infection caused by these parasites in tilapia Oreochromis niloticus Linnaeus, 1758 in aquaculture facilities in southeastern Mexico. A total of 240 fish were examined. The results showed that all doses using sodium were effective for controlling trichodinids and eliminated the parasites (100%) however, fish exposed to doses of formalin showed a higher level of stress than those exposed to sodium chloride. Bathing in formalin 0.250 mL L-1 for 10 min and 30 g L-1 of sodium chloride for 10 min, significantly reduced parasitic infection in tilapia under captive conditions (P < 0.05). This is the first record of a trichodinids species for native wild freshwater fish in a culture environment in southeastern Mexico since all previous records were from exotic cultured fish. The species found were Trichodina pediculus, T. compacta, T. nigra and T. centrostrigeata are new records of host and geographic location.

Squat lobsters are distributed worldwide and are ecologically important in deep-sea bottoms. Agononida longipes is reported as the most abundant squat lobster in the southern Gulf of Mexico, and also occurs along the coast of Brazil and in the Colombian Caribbean. This study aimed to describe the spatial and bathymetric distribution of biomass and size structure of the squat lobster A. longipes in the Colombian Caribbean. Specimens were collected in the Colombian Caribbean between 100 and 550 m of depth. A total of 826 deep-sea squat lobsters was caught and analyzed. The size of A. longipes females and males ranged from 21.17 to 57.43 mm TL (mean 45.07 ± 5.51 mm) and from 23.59 to 54.85 mm TL (mean 42.96 ± 5.60 mm), respectively, revealing smaller mean sizes for males than for females. The length-weight relationship showed negative allometric growth for both sexes. Agononida longipes presented the highest abundance in the depth strata 300-400 m with the highest biomass in front of Riohacha in the northern zone and front of Cartagena in the southern zone. The highest abundance of this species in the northern zone of the Colombian Caribbean coincided with a high diversity of other potential deep-sea fishing resources. The knowledge about the distribution, abundance and life cycle of A. longipes is imperative for proper management under an ecosystem approach.

Promising species for aquaculture need to have their nutritional requirements defined. Considering that protein is the most expensive macronutrient in aquaculture diets, the present study aimed to estimate the protein requirement of curimatã-pacu fed with diets containing two lipid levels. Thus, eight experimental diets were formulated to contain 20, 25, 30 and 35% of crude protein (CP) associated to 11 and 15% of crude lipids (CL) were formulated, constituting a completely randomized factorial design (4 CP x 2 CL) with three replicates per treatment. The juveniles (3.6 ± 0.01 g) were fed daily with 6% of the biomass, three times a day (08:00, 12:00 and 16:00 h) for 70 days. The protein requirement was estimated by the combination of the broken line and quadratic regression models. The CP concentration in the diets was the only factor influencing (P < 0.05) the growth and feeding efficiency variables of the fish, without interaction (P > 0.05) with the CL level of the diets. The requirement for weight gain and fish feed efficiency was estimated at 32.5 and 34.5% CP. Protein retention decreased (P < 0.05) in proportion to CP elevation. Fish fed 15% CL had higher (P < 0.05) body lipid deposition. On the other hand, the increase of CP of the diets decreased (P < 0.05) lipid deposition in juveniles. Therefore, it is recommended that young curimatã-pacu between 3 and 27 g in weight should be fed diets containing 32.5-34.5% CP and 11% of CL, equivalent to a protein: energy ratio of 22-23 mg kJ-1.

The cephalic lateral line system of the Normanicthyidae family monotypic species, Normanichthys crockeri from Corral Bay, Chile was studied. N. crockeri is a small, schooling and pelagic fish from the southeast Pacific coast between Chimbote, Perú and Mocha Island, Chile. Normanichthys displays a cephalic latero sensorial system constituted by pores and canals. The pores are in six cephalic zones: five preopercular pores (pr.p), five mandibular pores (m.p), three supraorbital pores (so.p), eight infraorbital pores (io.p), three postorbital pores (po.p), three supratemporal pores (st.p) and only one coronary pore (c.p). The high number of pores distributed along the anterior, middle and posterior zones of the orbit stands out, making it a quite sensitive area. In the jaw, five elongated pores join those present in the preoperculum that, along with the rest of the cephalic pores in the supraorbital, supratemporal and postorbital regions make yet another area sensitive to the water flow. These pores are connected with eight narrow, continuous and simple canals: preopercular canal (PR), mandibular canal (MD), supraorbital canal (SO), infraorbital canal (IO), supratemporal canal (ST), otic canal (OT), post-otic canal (PO) and temporal canal (T). This type of canal is the most common pattern found among bony fishes and is designed to respond maximally to water flow velocity along the axis of the canal. These results will help understand part of the cephalic sensorial lateral line biology of this species, which has been barely considered in the ichthyological literature.

In the present study, the potential of three isolated microalgae strains from Bahía de La Paz, Baja California Sur, Mexico and identified as Schizochytrium sp. (Inner key: LPU-1), Chaetoceros sp. (LPU-2), and Chaetoceros sp. (LPU-3) for the cultivation of the rotifer Brachionus plicatilis was tested. The effects of isolated strains on the population growth and nutritional content (proteins, lipids, carbohydrates, and fatty acid composition) of B. plicatilis were evaluated. The feeding essay of B. plicatilis was carried out at 32 ± 2°C. Treatments were established using a monoalgal and dialgal diet: Schizochytrium sp. (LPU-1), Schizochytrium sp. (LPU-1)/Chaetoceros sp. (LPU-2), Chaetoceros sp. (LPU-2), Chaetoceros sp. (LPU-3), Chaetoceros sp. (LPU-2)/Chaetoceros sp. (LPU-3). The results show that the rotifers population growth ratio was higher with Schizochytrium sp. (LPU-1) 0.88 ± 0.43, Chaetoceros sp. (LPU-3), 0.87 ± 0.37, and from both 0.87 ± 0.40. The results show that the native microalgae of a North Pacific area mixed are an excellent source of nutrients for the growth and enhancement of the nutritional value of the rotifers, which can be used in the future to feed the larvae of marine fish more nutritionally and economically.