Mexican Eastern Research Articles

Cataphryxus zapoteca sp. nov. (Isopoda, Bopyridae) and new hosts and records of bopyrid isopods from the Mexican Eastern Pacific.

Based on the examination of diverse crustacean taxa collected along the Mexican Pacific and deposited in the Colección Nacional de Crustáceos of the Instituto de Biología, UNAM, six species of bopyrid isopods were detected. New hosts and localities are reported for Munidion pleuroncodis Markham, 1975, Probopyrus pacificensis Román-Contreras, 1993, Probopyrus markhami Román-Contreras, 1996, Progebiophilus bruscai Salazar-Vallejo & Leija-Tristán, 1990 and Schizobopyrina striata (Nierstrasz & Brender à Brandis, 1929). Cataphryxus zapoteca sp. nov., is described as abdominal parasite of the shrimp Lysmata galapagensis Schmitt; this bopyrid is the second species described in the genus Cataphryxus Shiino, 1936 and the first registered on the American continent. Taxonomic characters, distribution and some reproductive data for five of the six species examined are provided in order to update the knowledge of this parasite group in this Eastern Pacific region.

New Species of Rhabdosynochus Mizelle and Blatz 1941 (Monogenoidea: Diplectanidae) From the Gills of the Cultured Centropomus viridis (Perciformes) in the Mexican Eastern Tropical Pacific.

There are currently nine monogenoidean species of Rhabdosynochus infecting the gill lamellae of wild and cultured centropomid fishes from tropical and subtropical waters of the western Atlantic and eastern Pacific Oceans. The purpose of the present study was to describe the morphological distinctiveness of two new species of Rhabdosynochus found on the cultured Centropomus viridis collected from floating cages from the Mexican eastern Tropical Pacific in 2018. monogenoideans were fixed with 4-5% formalin solution, observed and measured as temporary or permanent mounts stained with Gomori's trichrome, and mounted in Canada balsam. Other specimens were mounted on slides using a mixture of lactic acid (LA) and glycerin-ammonium picrate (GAP) and then remounted in Canada balsam to obtain measurements of the haptoral structures and copulatory complex. Illustrations were prepared with the aid of a drawing tube using a Leica microscope DM 2500 with Nomarski interference contrast. Rhabdosynochus viridisi n. sp. is mainly differentiated from all other congeneric species in the shape and size of their copulatory complexes, i.e., length 75-105µm vs. 45-55µm in R. alterinstitus, 26-44µm in R. volucris, 19-22µm in R. lituparvus, 21-37µm in R. siliquaus, 48-75µm in R. hargisi, 37-44µm in R. hudsoni and 44-61µm in R. guanduensis. Rhabdosynochus pacificus n. sp. differs from all other species of the genus in having an accessory piece (one subunit) distally twisted. Based on the morphometric differences of the two new species described above, the number of valid species of Rhabdosynochus has now increased to 11. These two new species of Rhabdosynochus represent the first described species of the genus on C. viridis.

Redundancy and diversity of functional reef fish groups of the Mexican Eastern Pacific

AbstractCoral reefs are in crisis worldwide. Fish play a key role in the resilience of reefs because most of the biomass of the ecosystem flows through them. Evidence indicates that the response to stressors will vary markedly depending on the resilience of the ecosystem. In order to assess the functional groups of reef fishes, morphometric and ecomorphological analyses were carried out on the shape and diet of 117 reef fish species from the Mexican Eastern Pacific (MEP) from 23°N to 15°N, spanning the years 2009–2012. Six trophic groups were identified and subdivided into 19 functional groups: (A) detritus and plants consumers, three morphologies; (B) plants and zoobenthos consumers, four morphologies; (C) zoobenthos consumers, two morphologies; (D) zoobenthos and zooplankton consumers, three morphologies; (E) zooplankton and nekton consumers, three morphologies; and (F) nekton consumers, four morphologies. Our main conclusions are: (i) fish communities of the MEP have a high degree of ecological redundancy; (ii) fish diversity is not related to the coral cover; and (iii) the combination of using both morphology and diet produce a more effective classification of functional groups. Future studies such as these will allow a deeper understanding of environment and it will help illuminate the effects of fish morphology and diet on population structure.

Habitat characteristics and environmental factors related to boring sponge assemblages on coral reefs near populated coastal areas on the Mexican Eastern Pacific coast

Coral reefs are undergoing global decline due to the environmental degradation of coastal areas through increasing human impacts from urban coastal development. Increases in the abundance of boring organisms are suggested to be a direct consequence of coral mortality and the exposure of calcareous substrates associated with deteriorated reef environments. The Mexican Pacific coast harbors coral reefs undergoing rapid degradation. In this study, we analyzed species richness and abundance of boring sponges associated with living corals, dead coral framework, and coral rubble from five coral reefs near the tourist destination of Zihuatanejo Bay, Guerrero. Environmental and habitat parameters indicative of human impacts on coral reefs were also recorded and analyzed. All coral reefs exhibited similar species richness (10–12 species), but sponge abundance (25–60 %) varied among the study sites. While dead coral framework and coral rubble were the preferred substrate types for boring sponges, the sites with the highest coverage of dead corals did not show the highest abundance of boring sponges. In fact, the reefs closest to the tourist site, which were weakly or moderately conserved, exhibited the highest levels of sponge abundance. These reefs also had the highest levels of δ15N (up to 9.5 ‰) and δ13C (−13.3 ‰) and high concentrations of chlorophyll a (1.8 mg m−3), which are indicative of wastewater impacts. In contrast, sites more distant from the tourist area, which were moderately or highly conserved, had less well-developed sponge assemblages. The analysis of environmental indicators showed comparatively high environmental quality for these sites, with water clarity values up to 7.5 m and chlorophyll a concentrations as low as 0.27 mg m−3. Differences in species composition were also evident among coral reef sites, with species such as Pione carpenteri, Thoosa calpulli, Siphonodictyon crypticum, Cliona mucronata and C. tropicalis dominating the more highly impacted sites. These results indicate that anthropogenic sources of nutrients may have a greater positive influence on the abundance of boring sponges on coral reefs near human populated sites.

Landfalling Tropical Cyclones along the Eastern Pacific Coast between the Sixteenth and Twentieth Centuries

Abstract Numerous studies have been conducted to document long-term trends in tropical cyclone (TC) activity. However, the eastern Pacific has not received as much attention as other basins. Here the authors attempt the identification of TC formation in the Mexican eastern Pacific Ocean before 1950. Using bibliographical and historical file consultation, they constructed a catalog of events related to intense storms and possible TCs that made landfall on the Mexican Pacific coasts. Between 1536 and 1948 they found a total of 119 events related to TCs. Then, using the Saffir–Simpson scale and the climatology of the region as the criteria to evaluate each event, they found 85 TCs. Furthermore, they constructed a historical time series of TCs between 1701 and 2010. The spectral analysis showed periodicities of ~2.6, 4, 5, 12, 16, 39, and 105 years that coincide with some large-scale climatic phenomena and also with solar activity. In particular, the ~12-yr cycle is the most persistent periodicity in this study.

Multicriteria analysis of log-set strata closures to reduce the mexican tuna fishery incidental catch

Concordance analysis, a multicriteria technique, was used as a decision-making tool. To exemplify the use of this tool, five closure options were evaluated to decrease incidental catch of mahi-mahi or dolphin-fish, Coryphaena spp., by the Mexican eastern Pacific tuna fishery using log-sets. The options consist of combinations of spatial and temporal strata subject to closures, and were evaluated using four eco-biologic and techno-economic criteria. A set of solutions was generated using 286 parametric representations of the weights-vector due to the difficulty of knowing the real preferences of decision-makers. The option with the highest probability of being chosen (almost 0.6) closes three large areas throughout the year for log-sets. This option would reduce mahi-mahi incidental catch in just over 85%, and almost 92% that of other species. However, this option represents the highest cost in terms of lost gross revenues and leaves only eight strata open for the log-set fishery.

Zooplankton Biomass Variability in the Mexican Eastern Tropical Pacific

The time and space distribution of zooplankton biomass recorded during a year cycle (December 1995-1996) off the Pacific coast of central Mexico is analyzed. Samples were obtained by surface (42-86 m) oblique hauls at 12 sampling sites using a Bongo net. The overall average displacement volume biomass of zooplankton during the surveyed period was 1138 cm3 / 1000 m3 . Principal component analysis indicated that highest biomass concentrations occurred at coastal stations. The months with highest biomass values were those in which the lowest sea surface temperature values occurred (January-May). This was the same period in which the California Current was strongest and clearly influenced the hydrological conditions of the surveyed area. In these months, advective processes are active along the outer shelf, favoring upwelling of colder, relatively nutrient-richer waters that promote an overall local increase of zooplankton activity and populations. The high variability of biomass values is indicative of episodic, localized processes that enhance productivity in the area.

In re The Interoceanic Railway of Mexico Limited, The Mexican Eastern Railway Company Limited, and The Mexican Southern Railway Limited.

Denial of Justice — Meaning of — Acts of Non-Judicial Authorities — Whether Constituting Denial of Justice — Effect on Calvo Clause.

The Interoceanic Railway of Mexico (Acapulco to Veracruz) (Limited), and the Mexican Eastern Railway Company (Limited), and the Mexican Southern Railway (Limited)

The Interoceanic Railway of Mexico (Acapulco to Veracruz) (Limited), and the Mexican Eastern Railway Company (Limited), and the Mexican Southern Railway (Limited)