Héctor Villalobos

Patrones históricos y escenarios térmicos futuros en mares mexicanos

Into different areas (e.g., academic, public) predictions of climate as part of the process of decision-making are required. Despite such information need, the inconsistency of global models to predict the state of the climate in small scales (regions) is widely recognized. Considering this, we tested predictions of sea surface temperature (SST) in 10 marine regions off the coast of Mexico. Using classification and regression trees, Mexican coastal states were grouped accordingly to their similarity in instrumental records of air temperature (AST). Such AST groups were considered explanatory variables together with regional climatic scale indices (e.g., Pacific Decadal Oscillation, PDO). Historical patterns of change (period, amplitude and phase) of AST and climate indices were characterized, and then its relationship with SST was analyzed using generalized additive models (GAM). The SST response to climatic scenarios was evaluated with 3 different forcing criteria. The GAM models showed significant fits and relatively high values of R² and deviance. Projections of regional climate variability showed substantial differences in comparison to the monotonic increase in SST global models outputs. The re-scaling strategy applied in this work for Mexican seas surface temperature, proved to be useful to integrate the historical variation with different forcing criteria.

Comparative anatomy of the caudal skeleton of lantern fishes of the genus Triphoturus Fraser-Brunner, 1949 (Teleostei: Myctophidae)

The caudal skeleton provides important information for the study of the systematics and ecomorphology of teleostean fish. However, studies based on the analysis of osteological traits are scarce for fishes in the order Myctophiformes. This paper describes the anatomy of the caudal bones of 3 Triphoturus species: T. mexicanus (Gilbert, 1890), T. nigrescens (Brauer, 1904) and T. oculeum (Garman, 1899). A comparative analysis was performed on cleared and stained specimens to identify the differences and similarities of bony elements and the organization of the caudal skeleton among the selected species. Triphoturus mexicanus differs from T. oculeum in the presence of medial neural plates and a foramen in the parhypural, while T. nigrescens differs from their congeners in a higher number of hypurals (2 + 4 = 6) and the separation and number of cartilaginous elements. This osteological description of the caudal region allowed updates to the nomenclature of bony and cartilaginous elements in myctophids. Further, this study allows for the recognition of structural differences between T. mexicanus and T. oculeum, as well as the major morphological distinction between T. nigrescens and their sister species.

Macro-Scale Patterns in Upwelling/Downwelling Activity at North American West Coast.

The seasonal and interannual variability of vertical transport (upwelling/downwelling) has been relatively well studied, mainly for the California Current System, including low-frequency changes and latitudinal heterogeneity. The aim of this work was to identify potentially predictable patterns in upwelling/downwelling activity along the North American west coast and discuss their plausible mechanisms. To this purpose we applied the min/max Autocorrelation Factor technique and time series analysis. We found that spatial co-variation of seawater vertical movements present three dominant low-frequency signals in the range of 33, 19 and 11 years, resembling periodicities of: atmospheric circulation, nodal moon tides and solar activity. Those periodicities might be related to the variability of vertical transport through their influence on dominant wind patterns, the position/intensity of pressure centers and the strength of atmospheric circulation cells (wind stress). The low-frequency signals identified in upwelling/downwelling are coherent with temporal patterns previously reported at the study region: sea surface temperature along the Pacific coast of North America, catch fluctuations of anchovy Engraulis mordax and sardine Sardinops sagax, the Pacific Decadal Oscillation, changes in abundance and distribution of salmon populations, and variations in the position and intensity of the Aleutian low. Since the vertical transport is an oceanographic process with strong biological relevance, the recognition of their spatio-temporal patterns might allow for some reasonable forecasting capacity, potentially useful for marine resources management of the region.