The spatial distribution of Farfantepenaeus shrimp was analysed in the Laguna Madre of Tamaulipas, Mexico. Sampling was carried out on submerged aquatic vegetation (SAV) habitats at five sites located along the coastal lagoon. Two nocturnal surveys were conducted during winter in 2005 (January–February), collecting a total of 3268 shrimp individuals. SAV beds were composed of a mixture of drift algae (mainly Digenia simplex), attached algae (mainly Penicillus capitatus and Udotea occidentalis) and seagrass (mainly Halodule wrightii). Farfantepenaeus aztecus was more abundant (39.5%) than F. duorarum (36.8%), and the remaining 23.7% corresponding to small unidentified Farfantepenaeus spp. were classified as recruits. Abundance of F. aztecus was significantly higher at sites 2 and 4, whereas F. duorarum did not show significant distribution differences along the Laguna Madre. Recruits, juveniles and total shrimp tended to decrease significantly at the northern part of the lagoon (site 1), where substrate was dominated by drifting algae and seagrasses were scarce or absent. The abundance of shrimp was positively related to seagrass biomass and/or water temperature, whereas there was a negligible or negative relationship with algal biomass. With the exception of subadults, a significant positive linear relationship between seagrass and shrimp abundance was fitted, indicating an increase in number of individuals of both species with increasing seagrass biomass. This suggests that seagrass is the most important component of SAV beds influencing the abundance of F. aztecus and F. duorarum along this hypersaline coastal lagoon.

The value of submerged aquatic vegetation (SAV) as a nursery habitat for penaeid shrimp has been recognised previously; however, the importance of SAV in terms of its distance from a tidal inlet (a site through which shrimp postlarvae migrate into coastal lagoons) has not been evaluated. In the present study, the effect of proximity to a tidal inlet on the relative importance of SAV beds for Farfantepenaeus shrimp was evaluated in the Laguna Madre of Tamaulipas (Mexico). Sampling was performed monthly from February to December 2005, diurnally and nocturnally, in two SAV bed areas, one 25km (distant) and the other 1km (nearby) from the inlet. Densities of shrimp (F. aztecus, F. duorarum and F. brasiliensis) were consistently higher in the nearby SAV bed during both the day and night. Water temperature was the most important explanatory variable of shrimp abundance in both SAV beds. The temperature–abundance relationship was negative in all cases, except in the distant SAV bed at night, when shrimp abundance was positively related to dissolved oxygen and salinity. The nearby SAV bed had higher recruit abundance and supported a greater numbers of juveniles and subadults. In contrast, shrimp abundance in the distant SAV bed was apparently limited by recruitment.

ABSTRACT. Biological response modifiers such as pro and prebiotics have been recently used in aquaculture showing abilities as immunostimulants, enhancing resistance to different fungal, bacterial and parasitic pathogens and tolerance to environmental stress. This experiment evaluated three different concentrations (0.05, 0.1 and 0.5%) of β-1,3/1,6 glucans on nonspecific immune parameters of channel catfish Ictalurus punctatus. Results showed that intake supplementation with 0.05% of β-1,3/1,6 glucans provides a greater immunostimulation over the fourth treatment week. Significant higher differences (P < 0.05) were obtained on parameters related to phagocytic activity on blood cells, also other assays showed more reactive cells to nitroblue tetrazolium (NbT) stain on spleen and head kidney analysis. We conclude that the use of 0.05% of β-1,3/1,6 glucans added to a commercial diet improves nonspecific immune system of channel catfish I. punctatus.

Seagrasses are critical habitats for the recruitment and growth of juvenile penaeid shrimps within estuaries and coastal lagoons. The location of a seagrass bed within the lagoon can determine the value of a particular bed for shrimp populations. Consequently, differences in the abundance of shrimp can be found in seagrasses depending on their location. As shrimp density increases, density-dependent effects on biological parameters are more likely to occur. However, knowledge about density-dependent processes on shrimp populations in nursery habitats remains limited. The present investigation was undertaken to examine the effects of population density on shrimp condition in two selected seagrass beds, located at different distance from a tidal inlet, one 25 km away (distant) and the other 1 km away (nearby), in a subtropical coastal lagoon. The study was based on monthly samplings during one year in Laguna Madre (Mexico), performing a total of 36 shrimp trawls (100 m2 each one) within each seagrass bed (n = 3 trawls per bed per month for 12 months). Shrimp density was related to the proximity to the tidal inlet (higher density was consistently observed in the nearby seagrass bed), which in turn adversely affected the condition of both species studied (Penaeus aztecus and P. duorarum). In this regard, the present study provides the first evidence of density-dependent effects on shrimp condition inhabiting a nursery habitat. Both shrimp species exhibited a negative relationship between condition and shrimp density. However, this pattern differed depending on the proximity to the tidal inlet, suggesting that shrimp populations inhabiting the nearby seagrass bed are exposed to density-dependent effects on condition; whereas, such effects were not detected in the distant seagrass bed. Shrimp density within the distant seagrass bed was probably below carrying capacity, which is suggested by the better shrimp condition observed in that area of the lagoon. Intra and interspecific competition for food items is surmised to occur, predominantly within seagrass beds near the tidal inlet. However, this hypothesis needs to be tested in future studies.

Lactoferrin is a mammalian cationic iron‐binding glycoprotein of the innate immune system that belongs to the transferrin family of proteins. Present in colostrum, milk and tears, and exhibiting a wide range of biological properties in vitro and in vivo, lactoferrin is a nutraceutical component used as a food supplement for humans. Evidence from veterinary medicine and animal production suggests the potential use of lactoferrin as a microbicide, microbiostatic, microbiota modulator or immunostimulant. Bovine lactoferrin is the most common type of lactoferrin in animal production research, because it is more easily produced and sold all over the world. Administering bovine lactoferrin to dairy cattle, chickens and pigs causes several physiological changes that may affect immune system behaviour, microbiota status and iron homeostasis. This could increase resistance to pathogens and, in some cases, improve growth performance. The present review analyses the in vitro and in vivo effects of bovine lactoferrin on fish species for human consumption. Although there is no consensus on how bovine lactoferrin can modify the physiology of fish in vivo, the results of in vitro assays suggest a similar molecular mechanism to that previously described in mammals.