Raymundo Avendaño-Ibarra

Fish larvae from the Gulf of California to Colima, Mexico: An update

An updated taxonomic list of marine fish larvae from the Gulf of California to Colima, Mexico is presented. A total of 579 taxa belonging to 119 families, 256 genera, and 423 species were recorded. The list was compiled using 14 publications on fish larvae research (1974-2012), and the fish larvae identified from 315 samples collected with Bongo nets during 10 oceanographic cruises made from the Gulf of California to Bahia de Banderas, Mexico, from 2003 to 2007 (this study). The most important families in this study were the Myctophidae (28.3%), Engraulidae (25.0%), and Clupeidae (15.4%). The most abundant species were Cetengraulis mysticetus (18.2%), Benthosema panamense (13.9%), and Opisthonema libertate (12.7%). The compiled taxonomic list shows the addition of 296 new taxa to the previous list published 10 years ago, and also the need of an increase in the effort on the taxonomy of fish larvae forms not identified to species level.

Fish larvae response to biophysical changes in the Gulf of California, Mexico (Winter-Summer)

We analyzed the response of fish larvae assemblages to environmental variables and to physical macro- and mesoscale processes in the Gulf of California, during four oceanographic cruises (winter and summer 2005 and 2007). Physical data of the water column obtained through CTD casts, sea surface temperature, and chlorophyll a satellite imagery were used to detect mesoscale structures. Zooplankton samples were collected with standard Bongo net tows. Fish larvae assemblages responded to latitudinal and coastal-ocean gradients, related to inflow of water to the gulf, and to biological production. The 19°C and 21°C isotherms during winter, and 29°C and 31°C during summer, limited the distribution of fish larvae at the macroscale. Between types of eddy, the cyclonic (January) registered high abundance, species richness, and zooplankton volume compared to the other anticyclonic (March) and cyclonic (September). Thermal fronts (Big Islands) of January and July affected the species distribution establishing strong differences between sides. At the mesoscale, eddy and fronts coincided with the isotherms mentioned previously, playing an important role in emphasizing the differences among species assemblages. The multivariate analysis indicated that larvae abundance was highly correlated with temperature and salinity and with chlorophyll a and zooplankton volume during winter and summer, respectively.

Influence of the oceanographic dynamic in size distribution of cephalopod paralarvae in the southern Mexican Pacific Ocean (rainy seasons 2007 and 2008)

The southern Mexican Pacific Ocean presents seasonal changes related to the rainy season and Tehuano winds, which generate mesoscale processes affecting biological productivity and marine biodiversity. Size distributions of squid paralarvae collected in this region during the rainy season (July 2007 and May-June 2008) were analyzed in relation to regional oceanography. Samples were collected through oblique hauls, and CTD casts were used to determine the structure of the water column. Between surveyed periods, there were no significant changes in the water temperature at 10 m, but there were significant variations in the mixed layer depth (MLD). The number of taxa, community composition and total abundance of paralarvae were similar between periods. However, in July paralarvae ≤2.0 mm were distributed along the margins of cyclonic and anticyclonic eddies associated with high temperatures. In May-June, the MLD and high concentrations of chlorophyll-a (Chl-a) determined the presence of a group of oceanic paralarvae and another of coastal paralarvae, separated by an upwelling front. The percentage of recently spawned paralarvae (≤2.0) nearly doubled during this period as a result of increased coastal sampling and high concentrations of Chl-a, indicating a coupling of adult reproduction with regional productivity. In the absence of winds, the mesoscale oceanographic complexity generates gradients and a differential effect on the distribution, transport and survival of cephalopod paralarvae.

Reproductive Strategies of Sea Basses based on Larval Abundance in Magdalena Bay, Mexico, 1982-1986

Abstract We analyzed the reproductive strategies of four sea basses Paralabrax spp. based on larval abundance and sea surface temperature during a period affected by the El Nino of 1982–1983. Zooplankton samples were taken monthly in the Magdalena–Almejas lagoon complex of Baja California Sur, Mexico, from January 1982 to November 1986. Larvae of four sea bass species were recorded; those of the spotted sand bass P. maculatofasciatus were dominant, contributing 43% of total abundance. Barred sand bass P. nebulifer constituted 28% of the sampled larvae, goldspotted sand bass P. auroguttatus contributed 26%, and kelp bass P. clathratus made up 3%. During 1983–1984, the larval abundances of spotted sand bass and goldspotted sand bass decreased (by >50% and 90%, respectively), while the abundance of barred sand bass increased by nearly 25%. A seasonal larval abundance maximum for all species was recorded in summer and autumn, but a differential reproductive pattern inferred from larval abundance was determine...