Search

This research study obtained the first morphological description of the Colorado snapper (Lutjanus colorado) larvae assisted by DNA barcoding as a molecular identification tool. Sixteen Lutjanidae larvae were separated from zooplankton samples and selected for this study. A fragment of the mitochondrial gene cytochrome oxidase subunit I (COI) of 658 bp was used in the analyses of intra‐ and interspecific genetic divergences; a neighbour‐joining tree (NJ) of K2P distances was performed with reference sequences of 15 Lutjanidae species from the Northeastern Tropical Pacific. Genetic divergences and the NJ tree identified 16 larvae as L. colorado. Morphological investigations of larvae at different developmental stages were performed; similarities and differences are discussed in comparison to four species described previously for the Northeastern Pacific. Pigmentation patterns were the best diagnostic features, particularly the caudal melanophores, at least up to 12.4 mm body length. [ABSTRACT FROM AUTHOR]

Effects of geostrophic kinetic energy flux on the three-dimensional distribution of fish larvae of mesopelagic species (Vinciguerria lucetia, Diogenichthys laternatus, Benthosema panamense and Triphoturus mexicanus) in the southern Gulf of California during summer and fall seasons of stronger stratification were analyzed. The greatest larval abundance was found at sampling stations in geostrophic kinetic energy-poor areas (<7.5 J/m3), where the distribution of the dominant species tended to be stratified. Larvae of V. lucetia (average abundance of 318 larvae/10m2) and B. panamense (174 larvae/10m2) were mostly located in and above the pycnocline (typically ~ 40 m depth). In contrast, larvae of D. laternatus (60 larvae/10m2) were mainly located in and below the pycnocline. On the other hand, in sampling stations from geostrophic kinetic energy-rich areas (> 21 J/m3), where mesoscale eddies were present, the larvae of the dominant species had low abundance and were spread more evenly through the water column, in spite of the water column stratification. For example, in a cyclonic eddy, V. lucetia larvae (34 larvae/10m2) extended their distribution to, at least, the limit of sampling 200 m depth below the pycnocline, while D. laternatus larvae (29 larvae/10m2) were found right up to the surface, both probably as a consequence mixing and secondary circulation in the eddy. Results showed that the level of the geostrophic kinetic energy flux affects the abundance and the three-dimensional distribution of mesopelagic fish larvae during the seasons of stronger stratification, indicating that areas with low geostrophic kinetic energy may be advantageous for feeding and development of mesopelagic fish larvae because of greater water column stability. [ABSTRACT FROM AUTHOR]

Larvae of the Californian anchovy ( Engraulis mordax) in the upper Gulf of California were identified. The finding was achieved with partial sequences of 16S rRNA (479 bp) and cytochrome c oxidase subunit I (580 bp) of mtDNA. High abundance of preflexion larvae (64 % of the sampling stations) in the northeastern upper Gulf, combined with environmental conditions (temperature: 17-18 °C; salinity: 35.8-36.0 g/kg; dissolved oxygen: 5.5-6.5 mL/L; chlorophyll a: 1.5-3.0 mg/m), support an undescribed spawning habitat of E. mordax in the Gulf of California. [ABSTRACT FROM AUTHOR]

In this work, we linked larval fish assemblages with water masses and circulation in the Eastern Tropical Pacific off Mexico, during autumn 2005 and winter 2007. Four assemblages were defined. (i) The “Transitional” assemblage, with the lowest mean larval abundance and dominated by tropical mesopelagic Vinciguerria lucetia and Diogenicthys laternatus. It was associated with modified California Current Water in winter and with modified Tropical Surface Water in autumn. (ii) The “Coastal-oceanic” assemblage was found off Cabo Corrientes, with high larval abundance, and dominated by Bregmaceros bathymaster; part of this assemblage was trapped by coastal cyclonic eddies. (iii) The “Tropical A” assemblage was associated with Tropical Surface Water. It had the highest abundance and richness, and the largest number of dominant species (e.g. D. laternatus, Auxis spp.); it covered a wider area in winter than in autumn. (iv) The “Tropical B” assemblage, distinguished by the highest abundance of V. lucetia, was present only in autumn; it was associated with overall anticyclonic circulation of warm Tropical Surface Water. The agreement between larval fish assemblage distributions, water masses and mesoscale dynamics indicates that the formation and permanence of assemblages depends on the interaction of spawning strategies of different species with large-scale and mesoscale processes. [ABSTRACT FROM PUBLISHER]

Bahía Concepción is one of the largest coastal bodies of water on the peninsular side of the Gulf of California, which is characterized by great fish species diversity. Spatial distributions of fish larvae in Bahía Concepciòn during June and November 1997 were analyzed; these months were representative of the extreme hydrographic conditions during an annual cycle in the Gulf. Zooplankton samples (333-mm conical net) and conductivity, temperature, and depth data were obtained at each sampling station. The Bray-Curtis dissimilarity index defined three groups of stations in June (mouth, central, and interior) and two in November (mouth and central-interior), which vary in species composition and dominance. In June, Gerreidae (Eucinostomus gracilis) and Clupeidae (Opisthonema sp.) larvae were the dominant species in the bay mouth; Sciaenidae type 1, Clupeidae (Harengula thrissina), and Pomacentridae (Stegastes rectifraenum) larvae were the dominant species in the central bay; and Gerreidae (E. dowii) larvae in the bay interior. The differentiation of three groups is associated with variations in hydrographic conditions recorded from the mouth to the bay interior, coinciding with a well-defined thermocline throughout the bay as a result of weak winds prevailing in the central Gulf region. In November, Mullidae and Clupeidae (Etrumeus teres) larvae were the dominant taxa in the bay mouth, and Gobiidae (Ilypnus gilberti) and Blenniidae (Hypsoblennius gentilis) larvae dominated in the central and interior bay. The similarity of the larval composition of the central and interior bay is associated with a straight spatial gradient of temperature and salinity and homogeneity in the water column; this condition was caused by strong winds and tides that affect the region in late fall. In addition, the presence of mesopelagic species (e.g., Vinciguerria lucetia) in the bay interior during November indicates a clear influence of the Gulf waters in the bay at that time, possibly as a result of intensive mixing. [ABSTRACT FROM AUTHOR]