SW Gulf Research Articles

A new deep-sea species of genus Bathypisella (Crustacea: Peracarida: Amphipoda) from bathyal soft bottoms, south-western Gulf of Mexico

ABSTRACT A new deep-sea species of the genus Bathypisella was collected from bathyal soft bottoms, SW Gulf of Mexico. This new species represents the second Bathypisella species known worldwide, which is characterised by head subequal in length to pereonal segments 1–2 combined, eyes absent, toothed pleonal and urosomal segments, 4-articulate accessory flagellum, coxae 1–4 posteroventral area slightly notched; coxa 4 posterior lobe absent, maxilliped palp article 3 in right angle, maxilla 1 inner plate with five lateral setae, left mandible with three teeth on lacinia mobilis, gnathopod 1 palmar margin convex, gnathopod 2 propodus palmar margin concave, one long, robust seta in palmar angle, epimeron 3 with trifid posteroventral margin, and telson cleft half its length. Besides a complete description of the new species, a dichotomous key to identify both Bathypisella species is provided. http://www.zoobank.org/urn:lsid:zoobank.org:pub:73A22DCA-2692-4C24-B008-E01F8E130B69

Machine learning-supported seismic stratigraphy of the Paleozoic Nubia Formation (SW Gulf of Suez-rift): Implications for paleoenvironment−petroleum geology of a lacustrine-fan delta

-Steeply dipping prograding fan deltas possess high reservoir quality facies that could be excellent targets while exploring for hydrocarbons. Due to their complex stacking nature, and limited examples, delineating their architectural elements is still challenging. In this paper we mainly performed sedimentary facies analysis; applying various disciplines e.g. sequence stratigraphy, seismic stratigraphy, GR-log motifs, and seismic waveform segmentation; so as to adequately depict the reservoir heterogeneity and quality of the Paleozoic Nubia clastics in West Esh El Mallaha Concession (southwest Gulf of Suez rift). Organic maturity prediction, to confirm the hydrocarbon charging from source units to reservoir intervals, was also of most importance in this study. Accordingly, 1D basin model was established to define the past geologic events; subsidence, and thermal maturity; and their controls on sedimentary basin evolution and associated petroleum potential. We utilized several key-information scales; e.g. wireline logs, and seismic profiles. Linking different disciplines applied in this study points to a successful integrated reservoir characterization workflow capable of unfolding ancient environments and the associated hydrocarbon potential. The results show that Nubia Formation was built during the lowstand−transgressive phase of a 3rd order depositional sequence. It encompasses fluvio-lacustrine system with eight sedimentary facies associations; form source to sink. Fluvial channels and mouth bars, settled in subaerial and subaqueous settings respectively, represent the most significant reservoir facies in the area. Given best hydrocarbon-reservoir quality, the deltaic mouth bars ought to attract attention of further oilfield development plans and be considered while investigating similar settings. • Integrated facies analysis, and established depositional model, depicting reservoir architectural elements; heterogeneity. • TOC calculations and 1D-basin modeling confirming hydrocarbon charging from source-prone intervals to reservoir zones. • Lacustrine deltaic mouth bars representing best reservoir facies ought to be tested and considered in similar settings. • Combined facies analysis and basin modeling devoting to robust insight into environments and associated petroleum potential.

Germination of Pyrodinium bahamense Cysts from a Pristine Lagoon in San José Island, Gulf of California: Implications of Long-Term Survival

The production of cysts by dinoflagellates can be part of the life cycle of some species, improving their survival under adverse environmental conditions; cyst germination may explain the recurrence of algal blooms in some cases. In order to evaluate the germination rates of Pyrodinium bahamense, its cysts were retrieved from surface sediments collected in San José Lagoon, SW Gulf of California, and germination assays were carried out through the cysts incubation under two contrasting light and nutrient concentration conditions. Also, to evaluate cysts viability, we isolated P. bahamense cysts and other dinoflagellate species from different depth layers of a 210Pb-dated sediment core (~100 years) to examine their germination for 20 days. Germination rates were higher under light (28–56%) than in darkness (23–34%); there were indications that the nutrient-enriched media was more effective in promoting germination than seawater. Furthermore, germination was observed in cysts isolated from all selected core depths, even those corresponding to ~100 years. These results demonstrate that cysts remain viable for long periods, and P. bahamense cysts germinate in any light and nutrient conditions. The results of this research provide relevant information to understand its physiology and complex population dynamics. This species should be closely monitored in the area in the context of climate change, as current natural conditions are likely to change.

The reef fish assemblage of a coral reef system in the southwestern Gulf of Mexico

Reef fish species richness of the Veracruz Reef System National Park (VRSNP) in the SW Gulf of Mexico is well known. However, the knowledge of the assemblage structure and its spatial variability in the reef ecosystem is quite limited. For that purpose, 5 field surveys (2012-2015) were performed, using the stationary visual census method, at 10 selected reefs. The most important findings were: 116 reef species were recorded. Average total reef fish density (2.31 Ind/m2) is similar to the records for the Caribbean reefs in the 20th century. The top 5 most abundant species were: Chromis multilineata, Ocyurus chrysurus, Abudefduf saxatilis, Stegastes leucostictus, and Elacatinus jarocho. We found evidence of a spatial distribution pattern with 3 well-defined groups of reefs: (1) those near the city of Veracruz, (2) those near the outlet of the Jamapa River, and (3) those farther from the city. Higher fish densities are associated to both high hermatypic coral and low crustose coralline algae bottom covers. The assemblage structure of reef fishes is different at distinct geomorphological reef zones. As expected, with some differences in the species abundance order, the assemblage structure of reef fishes is similar at all coral reefs in the Gulf of Mexico.

Textural characteristics and abundance of microplastics in Tecolutla beach sediments, Gulf of Mexico.

Abundance of microplastics in coastal sediments is considered an emerging pollution problem worldwide. In Mexico, studies focused on microplastics in coastal sediments are little. In this study, we analyzed the textural characteristics and investigated the abundance of microplastics in the Tecolutla beach sediments, SW Gulf of Mexico. The extraction of microplastics in sediments was done by density separation. Microplastics were identified by stereomicroscope and scanning electron microscopy, and were classified based on their morphology, color, length, texture, and abundance. Among 181 microplastics, fiber type is predominant (number of microplastics n = 166; 92%) and followed by film (n = 12; 6%) and fragment (n = 3; 2%) types. The most abundant color of microplastics is black (n = 81; 45%) and second dominant color is blue (n = 65; 36%); most of them are fiber type. Based on the textural characteristics of sediments, it was observed that microplastics were derived from the fluvial contribution of the Tecolutla River and were deposited in the coastal environment by ocean currents. This study revealed that the abundance of microplastics was high in fine-grained sediments and was directly proportional to skewness. The results of this study can act as a reference for understanding the abundance of microplastics in the Gulf of Mexico coastal sediments.

Geochemistry of marine sediments adjacent to the Los Tuxtlas Volcanic Complex, Gulf of Mexico: Constraints on weathering and provenance

The provenance of GoM45 and GoM63 core sediments recovered in the deep-sea area (∼1666 m–1672 m water depth, respectively), in front of the Los Tuxtlas volcanic field, Gulf of Mexico was analyzed based on the textural, mineralogical, and geochemical variations. The radiocarbon age data of Globorotalia menardii group foraminiferal species varied from 17,709 to 20,711 calibrated years B.P for the sediment core GoM45, which represent Pleistocene/Holocene boundary. The core sediments were characterized by detrital components with enriched SiO2, Al2O3, and Fe2O3 concentrations. The weathering indices like Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Plagioclase Index of Alteration (PIA) revealed a low intensity of weathering for the core sediments.The V/Cr, Ni/Co, Cu/Zn, and V/Cr elemental ratios indicated an oxic depositional environment for the Gulf of Mexico deep sea area. In addition, the geochemistry data indicated a passive margin setting, which is consistent with the geology of the Gulf of Mexico. The trace and rare earth element concentrations, and Eu anomaly indicated that the sediments were derived from the natural erosion of andesitic and basaltic rocks in the Los Tuxtlas region, SW Gulf of Mexico. Los Tuxtlas region is partly influenced by the Papaloapan and Coatzacoalcos Rivers, which discharges into the SW Gulf of Mexico.

A Checklist of Benthic Amphipods (Crustacea: Peracarida) in Coral Reefs of the Protected Area Tuxpan-Lobos, Mexico, SW Gulf of Mexico

Currently, there is scarce information documenting benthic amphipod species in the Marine Protected Area Tuxpan—Lobos Coral Reef, a carbonate ecosystem in the southwestern Gulf of Mexico (GoM). Sampling to determine the biodiversity of benthic amphipods associated with several living or hard—soft bottom substrates occurred in July 2014, with 1,386 individuals collected at depths of 0.5–25 m. This study summarizes the first inventory of these benthic amphipods, and includes 64 species belonging to 30 genera, 19 families, and 3 suborders. The suborder Senticaudata was highly diverse with 36 species representing 56% of the total species. The most diverse amphipod families were Aoridae, Maeridae, Colomastigidae, Leucothoidae, Ampithoidae, and Photidae, which constitute 63% of the amphipod fauna collected. Nineteen species were characterized as dominant in the Tuxpan—Lobos coral reef system. Leucothoe ashleyae, Bemlos unicornis, Ampithoe ramondi, Elasmopus levis, E. pocillimanus, and E. rapax occurred in the highest abundance with the widest spatial distribution in this protected area. Macroalgae tufts, sponges, and coral rubble hosted the maximum amount of amphipod species. Based on the richness of amphipod species, the Tuxpan—Lobos Coral Reef system has the third highest amphipod species diversity in a coral reef ecosystem, after Alacranes and Sisal reefs, both located in the southern GoM.

Mineralogy and geochemistry of Tecolutla and Coatzacoalcos beach sediments, SW Gulf of Mexico

Mineralogic and geochemical studies were performed in the Tecolutla and Coatzacoalcos beach sediments, located at the SW Gulf of Mexico. The main concern of this article is to infer the weathering, provenance, and degree in which trace metal pollution affects the beach sediment composition. The chemical index of weathering (CIX) for the Tecolutla and Coatzacoalcos beach sediments indicate a moderate intensity of weathering in the source area. The SiO2/Al2O3 ratio values (>6) in the Tecolutla and Coatzacoalcos sediments suggested a high compositional maturity and recycling. A difference in the Al2O3/TiO2 ratios between the Tecolutla and Coatzacoalcos beach sediments points out that the sediments were derived from intermediate and felsic igneous rocks, respectively. A negative correlation for Al2O3 against TiO2 and P2O5, and trace elements Y, Nb, V, Sc, and Cr for the beach sediments suggests an association of these elements with detrital minerals rather than aluminosilicates. The provenance discrimination based on major element concentrations indicates an intermediate and a felsic provenance for the Tecolutla and Coatzacoalcos sediments. The major and trace element geochemistry of beach sediments are associated with a passive margin setting.The Enrichment factor (EF) and Geo accumulation index (Igeo) values show that the Tecolutla sediments are moderately enriched by Cu (EF ∼ 10–17) and Cr (1< Igeo <2). An enrichment of EF value for Cu in Tecolutla beach sediments may be a response of anthropogenic and natural sources by the weathering of intermediate igneous rocks. The moderately to highly enriched Igeo values of Pb, Zn, and V observed in the Coatzacoalcos beach sediments, indicate that the sediments were influenced by the waste generated by urban activities in the river drainage catchment area.

Larvae and macro-crustaceans along the coastline of the Parque Nacional Sistema Arrecifal Veracruzano, SW Gulf of Mexico

Larvae and macro-crustaceans along the coastline of the Parque Nacional Sistema Arrecifal Veracruzano, SW Gulf of Mexico

Provenance and palaeoenvironmental significance of microtextures in quartz and zircon grains from the Paseo del Mar and Bosque beaches, Gulf of Mexico

Microtextures of quartz and zircon grains from the Bosque and Paseo del Mar beaches in the Gulf of Mexico were examined using a Scanning Electron Microscopy (SEM), to infer their provenance and palaeoenvironment. A total of 16 microtextures from 200 grains were identified and were grouped into mechanical, chemical, and mechanical/chemical origin. Microtextures of mechanical origin represent parallel striations (ps), cracks due to collision (ck), conchoidal fractures (cf), v-shaped marks (vs), abrasion fatigue (af), meandering ridges (mr), chattermarks (ch), curved (cg) and straight grooves (sg), which are attributed to a high-energy fluvial and sub-aqueous marine environment. Solution pits (sp), crystal overgrowth (cro), and silica globules (sgl) of chemical origin indicated precipitation and dissolution in a silica saturated marine environment. Adhered particles (ap), elongated depressions (dp), and relief are grouped as mechanical/chemical origin, suggested a sub-aqueous nearshore marine environment. Although zircon is considered as a resistant mineral, the frequency of microtextures observed was higher in zircon than in quartz. The results of this study revealed that the Los Tuxtlas volcanic field, Chiapas Massif and Oaxacan Complexes in the SW Gulf of Mexico are the potential source areas, which supplied sediments to the Paseo del Mar and Bosque beach areas.

Detrital zircon U\u2013Pb geochronology and geochemistry of the Riachuelos and Palma Sola beach sediments, Veracruz State, Gulf of Mexico: a new insight on palaeoenvironment

Zircons are abundant in the beach sediments. In this study, surface microtexture, mineralogy, bulk sediment geochemistry, trace element composition and U–Pb isotopic geochronology of detrital zircons collected from the Riachuelos and Palma Sola beach areas, southwestern Gulf of Mexico were performed to infer the sediment provenance and palaeoenvironment. The zircon microtexture was categorized as mechanically- and/or chemically-induced features. The weathering index values for the Riachuelos (~ 72–77) and Palma Sola (~ 71–74) beach sediments indicated moderate weathering of both of the two source areas. The major and trace element data of bulk sediments suggested passive margin settings for the two areas. The trace elemental ratios and chondrite-normalized rare earth element (REE) patterns of bulk sediments revealed that the sediments were likely sourced by felsic and intermediate igneous rocks. And the zircon Th/U ratios (mostly more than 0.2) and zircon REE patterns (with negative Eu and positive Ce anomalies) suggested a magmatic origin for both of the beach sediments from these two areas. Two distinct zircon age peaks respectively belonging to the Paleozoic and the Cenozoic were identified both in the Riachuelos and Palma Sola beach sediments. Zircon geochronology comparison research between the Riachuelos–Palma Sola beach sediments and potential source areas in SW Gulf of Mexico revealed that the source terrane supplied the Paleozoic zircons of this study was identified as the Mesa Central Province (MCP), and the Cenozoic zircons were transported from the nearby Eastern Alkaline Province (EAP). Moreover, although the Precambrian zircons were very few in the studied sediments, their geochronology and geochemistry results still could infer that they were contributed by the source terranes of Grenvillian igneous suites in the Oaxaca and the Chiapas Massif Complexes.

Distribution of genus Jassa (Amphipoda, Ischyroceridae) in the Bay of Campeche, SW Gulf of Mexico, with a description of a new deepwater species

The genus Jassa includes 36 species distributed mainly in shallow waters as biofoulers on human-made structures or associated with living or inert soft bottom substrata worldwide. During the oceanographic cruise "2013-PEMEX Exploración y Produción, Regiones Marinas" in the southwestern Gulf of Mexico, several benthic amphipods of the genus Jassa were collected in sediments of both the continental shelf and the deep benthic sea. The present study examined the geographic and bathymetric distribution of Jassa in the Campeche Salt Basin, SW Gulf of Mexico, and described a new Jassa species collected below the isobath of 200 m. The species Jassa marmorata and Jassa morinoi were recorded mainly in front of the Usumacinta/Grijalva River Basin and Terminos Lagoon Delta, between 21 and 55 m depth. In contrast, the new species was recorded in the Bay of Campeche and the Campeche Canyon, below 450 m depth. For J. morinoi, it is the first register in the Gulf of Mexico. The new species increased the number of Jassa species documented worldwide to 37, and that of the deep-sea benthic amphipods from the Gulf of Mexico to 19 species.

New hosts and distribution records for bopyrid isopods parasitising alpheid shrimps (Decapoda, Alpheidae) in the SW Gulf of Mexico and Mexican Caribbean

ABSTRACT Based on the examination of alpheid shrimps from the SW Gulf of Mexico and the Mexican Caribbean, deposited in two scientific collections housed in the Universidad Nacional Autónoma de México, we document for the first time Synalpheus curacaoensis, Alpheus cristulifrons and A. estuariensis as hosts of bopyrid isopods, and for the latter alpheid species is confirmed their distribution in Mexican coasts. Similarly, the bopyrids Capitetragonia alphei and Parabopyrella lata are recorded for the first time along coasts of Mexico. New hosts are reported for Bopyrione synalphei, on Synalpheus elizabethae; Parabopyrella mortenseni, on Alpheus normanni and A. cristulifrons; and Eophryxus subcaudalis on Synalpheus anasimus. The distribution range of Bopyrella harmopleon is extended and new localities are reported for B. synalphei, P. mortenseni and E. subcaudalis. Morphological remarks for the six bopyrid species are provided and reproductive data (fecundity and embryo size) are given for five of them.

First record of Pseudaeginella arraialensis (Amphipoda: Caprellidea) from the Gulf of Mexico

During a sampling campaign in Puerto Progreso, Yucatan, Mexico, several specimens of the caprellid Pseudaeginella arraialensis were collected. They were attached to buoys as part of fouling communities between 0.5-12 m depth. The present study represents the first record of P. arraialensis for the Gulf of Mexico, increasing its geographical distribution range 7,500 km northwards, from Arraial do Cabo, Brazil to Puerto Progreso, Mexico, SW Gulf of Mexico.

A new deep-sea species of the genus Gracilimesus (Isopoda: Asellota: Ischnomesidae) from the Bay of Campeche, southwestern Gulf of Mexico

A new deep-sea species of isopod is described and illustrated. The material was collected in soft substratum in the Bay of Campeche, SW Gulf of Mexico, at a depth of 2,548 m aboard the research vessel “Justo Sierra” on September 4, 2009. Gracilimesus tzasnae sp. nov. can be distinguished from all other known species by its antennula with 5 articles; uropod length vs. pleotelson 0.3×; pereonite 7 not reduced; pereopod 7 absent; pleotelson dorsal surface smooth and not separated in lateral fields. The new species represents the first described Gracilimesus in the Gulf of Mexico. We present a table with the most important diagnostic characters to separate all the known species of the genus Gracilimesus .

Diatom record of progressive anthropopressure in the Gulf of Gdańsk and the Vistula Lagoon

Abstract This study describes the subfossil diatom flora in the surface sediments of the Polish coastal waters in relation to human impact. The material studied consists of the uppermost parts of seven sediment cores collected from the SW Gulf of Gdańsk and eight cores from the Vistula Lagoon. Our results show the present-day ecological state of both basins just before the planned construction of a navigable channel of the Vistula Spit, which will be the next factor affecting their hydrology. In different parts of the Gulf of Gdańsk, cultural eutrophication resulted in a distinct “anthropogenic assemblage” in the surface sediments. Its structure relates directly to the distance from the mouth of the Vistula River. In the surface assemblages of the Vistula Lagoon, the number of salt-tolerant diatoms increased with the salinity of the basin. Locally, a large number of pollution-resistant taxa was also observed.

Coral reef tanaidacean assemblages along the SW and SE Gulf of Mexico: biodiversity, geographic distribution and community structure

ABSTRACTThe biodiversity, geographic distribution, and community parameters of the benthic tanaidaceans associated with three coral reefs along the SW and SE Gulf of Mexico were analysed. A total of 15,525 specimens were grouped in 36 species. The highest value of abundance was found in the PNSAV with 6382 tanaidaceans. The PNSAV presented 30 species, the ANPT-L 16 species, and the SABS 17 species. The species with the widest distribution were Pseudonototanais sp., Condrochelia dubia, Leptochelia forresti, Synapseudes sp., Haplopolemius propinquus, Alloleptochelia longimana, and Paradoxapseudes bermudeus. In the Veracruz System Reef, the highest abundance was recorded for Condrochelia dubia and Pseudonototanais sp. The highest value of diversity was obtained in the SABS (3.08 bits/ind in the reef Bajo Diez), and the lowest value was found in the PNSAV (0.07 bits/ind in the reef Isla de Enmedio). The highest value of abundance was found in coral rubble and macroalgae. A significant relationship between depth and specific richness was found in the three reef systems. Using cluster analysis, three groups were found in each system, mainly related to the proximity to the coast and to urban areas. This is one of the first studies to show the specific substrate and attributes of three communities of tanaidaceans along the SE–SW coast of the Gulf of Mexico.

Total Mercury in Squalid Callista Megapitaria squalida from the SW Gulf of California, Mexico: Tissue Distribution and Human Health Risk.

We evaluated the total Hg concentration in different tissues of squalid callista Megapitaria squalida in order to measure Hg distribution in tissue and to estimate human health risk. Samples were obtained by free diving in the SW Gulf of California, Mexico. Concentrations are given on a wet weight basis. A total of 89 squalid callista specimens were obtained, presenting an average Hg concentration of 0.07 ± 0.04µg g-1. There were no significant differences (p > 0.05) in Hg concentration between tissues (visceral mass = 0.09 ± 0.08µg g-1; mantle = 0.06 ± 0.07µg g-1; muscle = 0.06 ± 0.04µg g-1). The low Hg values found in squalid callista and its low risk quotient (HQ = 0.03) suggest that the consumption of squalid callista does not represent a human health risk. However, HQ calculated using MeHg was > 1, it which could indicate a potential risk related to consumption of clams.

A new deep-sea Psammogammarus species (Crustacea: Amphipoda: Eriopisidae) from the continental slope of the SE Gulf of Mexico

ABSTRACTA new deep-sea species of amphipod collected at a depth of 1317 m from the soft bottom of the Bay of Campeche, SW Gulf of Mexico, is herein described. The sediment included a high proportion of silt and organic carbon. The specimen examined in this study was collected during the Oceanographic Expedition Xcambó-4, along the Bay of Campeche, aboard the RV Justo Sierra. The new species represents the sixteenth known species of the genus Psammogammarus worldwide. This new species is the second Psammogammarus recorded from the deep sea, and the first record of the genus for the Gulf of Mexico. Identification keys to males and females of Psammogammarus species are provided. Psammogammarus barrerai sp. nov. is characterised by head with anteroventral notch present; gnathopods 1 and 2 palmar margins oblique, and basis of pereopod 7 forming a wide serrated posterior lobe.www.zoobank.org/urn:lsid:zoobank.org:pub:C843777B-FF15-4AEC-B046-6513A96A9BFF

Environmental forcing on the flux of organic-walled dinoflagellate cysts in recent sediments from a subtropical lagoon in the Gulf of California

To evaluate the relationship of changes in organic-walled dinoflagellate cyst (dinocyst) fluxes to sediments with environmental variables (air and sea surface temperatures, El Niño conditions, rainfall, and terrigenous index), cyst assemblages were analyzed in a 210Pb-dated sediment core (~100years) from the pristine San José Lagoon (San José Island, SW Gulf of California). The dinocyst abundance ranged from 3784 to 25,108cystsg−1 and fluxes were of the order of 103–104cystscm−2yr−1. Lingulodinium machaerophorum, Polysphaeridium zoharyi and Spiniferites taxa accounted for 96% of the total dinocyst assemblages, and the abundances of these species increased towards the core surface. P. zoharyi fluxes increased from about 1965 onwards. Redundancy analyses, showed that mean minimum air temperature and terrigenous index were the key factors governing dinocyst fluxes. In this study, dinocyst fluxes of dominant taxa had responded to changes in climate-dependent environmental variables during the past ~20years; this may also be the case in other subtropical coastal lagoons.