Seasonal and interannual variability in the density of the postlarvae of Litopenaeus setiferus and Farfantepenaeus duorarum in Términos Lagoon, Gulf of Mexico

White shrimps, Litopenaeus setiferus (Linnaeus, 1767) and pink shrimps, Farfantepenaeus duorarum (Burkenroad, 1939) are two pivotal species in the southern Gulf of Mexico, due to their ecological and economic importance. In this study we present observational evidence of the seasonal and interannual variability of both species in the Términos Lagoon (southern Gulf of Mexico). The results suggest that the hydrography of the water column and the surface circulation exert a strong influence on the density of both species. The results presented here contribute to a better understanding of the dynamics of both species and highlight the need to combine different methodologies to achieve a better interpretation of this system.

Environmental variation vs co-occurrence of two fish families (Gerreidae and Ariidae) in Terminos Lagoon, Campeche, Mexico

Terminos Lagoon is recognized as an ecosystem of great diversity and productivity in the southern Gulf of Mexico. It is also the site of various anthropogenic activities in the lagoon as well as in its surroundings. In addition, in recent years this lagoon has showed variations in temperature and salinity as a result of global warming and/or watershed management. This has generated variations in the structure and function of fish communities, among other taxonomic groups. IIn this work, we analyze the changes in abundance and distribution associated with modifications in the salinity of fish species from two key families (Ariidae y Gerreidae) during the years 1980, 1998, and 2011. Salinity is analyzed in the three periods (ANOVA, Tukey (HSD); the abundance of species, environmental breadth according to salinity (Levins Index), environmental overlap (Pianka Index), and co-occurrence (C-score) are also analyzed. Statistical differences were tested using the null model. The results showed high variability in salinity, with a tendency to increase during the studied period with 24.7, 27.9, and 28.4 UPS for each year, respectively (p < 0.0001). The abundance of both families increased from 1980 to 1998 and decreased in 2011 (82% for Ariidae and 62% for Gerreidae). The C-score ranged from 1.07 in 1980 to 0.78 in 1998 and 2.71 in 2011. The observed averages were significantly lower than the simulated average (P <0.0001). In conclusion, the increase in salinity is probably one of the causes of a variation in the abundance of fish species. According to a possible more limited competition for space, fish abundance and C-score fluctuated inversely, indicating a trend towards a more generalist fish community. Keywords: Environmental breadth, environmental overlapping, co-ocurrence, and salinity gradient.

Record of changes in the regionalization of Terminos Lagoon, Campeche

The Terminos Lagoon is an estuarine-lagoon ecosystem, recognized as one of the largest coastal lagoons in the Gulf of Mexico, has great ecological, social and economic relevance, being a place from which various activities of commercial importance are carried out, in addition to being an area that presents high diversity. However, in the last 20 years it has been influenced by anthropic and natural impacts, which modifies the physicochemical characteristics of the water (temperature, salinity and pH) and changes in diversity species, being decisive in changes in regionalization. Therefore, in the present study, the spatio-temporal relationship of the physicochemical characteristics was analyzed, using geostatistics to characterize and predict possible new hydrological zones for Terminos lagoon. Samples were carried out monthly at 17 points, by zones and seasons (dry, rainy and wind/winter), in which significant differences were sought. To detect possible changes in regionalization, the GS+ software was used, where the values ​​of R2 were considered, defining the interpolation of Minimum Curvature (R2 <0.5). For the spatial distribution, the TNTmips program was used and to restructure the current zoning, a Cluster Analysis was applied. The results indicate for rainy season higher temperature values ​​(30.59 °C), higher salinity in dry (31.78 UPS), and higher pH in the wind/winter season (7.88). In the spatial distribution, the warmest areas were shown in the Candelaria River, the most saline areas by Isla de Carmen and the highest pH ranges near Pom-Atasta. According to the previous regionalization, 4 new zones are represented, which are influenced by fresh water discharges and the intrusion of salt water that is carried within the site. Keywords: Gulf of Mexico, ecosystem, refuge area, alterations, geostatistics.

Morphological aspects and its influence in the ecological role of two simpatric species (Lagodon rhomboides and Archosargus rhomboidalis) in Terminos lagoon, Mexico

In Terminos Lagoon the Sparidae family is represented mainly by Lagodon rhomboides (Lr) and Archosargus rhomboidalis (Ar), both reported with herbivorous habits, however, the record of carnivorous or omnivorous habits in other regions raises questions about the correct classification of the ecological role they play and the influences that morphological aspects may have (e.g. oral difference and intestine length). The objective was to analyze the trophic role (amplitude, overlap and trophic level) through the stomach content and its possible relationship with the morphological aspects of L. rhomboides. and A. rhomboidalis during three climatic seasons (30 individuals per species per season). As results, 180 individuals were analyzed with an average total length of 14.0 ± 2.5 (cm) for both species. According to the Index Importance Geometric (IGI), Thalassia testudinum was the main item of L. rhomboides (IGI= 86.3) and A. rhomboidalis (IGI= 63.3), however, the secondary items for A. rhombiodalis (Brachidontes (Hormomya) exustus= 5.70) and L. rhomboides (Parvilucina (Parvilucina) multilineata= 16.80) were different. The trophic breadth (“Bi”) indicated that L. rhomboides. and A. rhomboidalis are specialists (BiLr= 0.02 and BiAr= 0.01). At the intraspecific level, there is high similarity (ANOSIM) in the diet of both Sparids between seasons (RLr= 0.03 and RAr= 0.05), however, at the interspecific level, low similarity was observed (Rg= 0.15), which was reflected in the NT of both Sparids (NTLr= 2.22 and NTAr= 3.71). The average buccal area was smaller in L. rhomboides (12.90 mm) compared to A. rhomboidalis (13.07 mm). Based on the intestinal index, L. rhomboides is classified. (Ii= 2.20) as herbivore, and A. rhomboidalis (Ii= 0.71) as carnivore. In conclusion, both species presented differences in trophic roles, probably related to specific morphological aspects. This information is relevant to know the vulnerability of a species from simulation studies to different phenomena such as climate change. Keywords: Herbivore, Gulf of Mexico. Protected Natural Area, ANOSIM and Coastal Lagoons.

Spatial-temporal behavior of benthic communities in the Terminos Lagoon, Mexico: Possible areas of protection and conservation

Terminos Lagoon is classified as a Flora and Fauna Protection Area due to the high biodiversity it registers, however, given its size, it makes total protection difficult. The objective of this study was to detect possible specific areas of conservation within the lagoon, for which an analysis of the spatiotemporal behavior of biodiversity was carried out (based on geostatistics) and thereby establish key regions of laguna de Terminos for their protection and recovery. Monthly samplings (2016-2017) were carried out by trawling with a shrimp net in 17 stations classified in 4 regions during dry (February-May), rain (June-September) and wind/winter (October-January). The organisms were identified up to the species level and the indices of abundance, richness and diversity were applied to carry out the interpolation and generation of maps. 17,950 organisms (382.9 kg) were collected and 103 species were identified. According to the interpolation of minimum curvature, at the temporal level, the rainy season was the one that presented the highest values in terms of diversity and richness, while at the spatial level, region 1 (adjacent area of Boca Atasta and Palizada river) it was the most representative during the three climatic seasons for both indices. In terms of abundance, region 2 was the one characterized by presenting the highest values. In conclusion, regions 1 and 2 represent areas of great ecological importance for the balance of biodiversity, which is why they are key areas that should be protected in Terminos Lagoon. This information would contribute significantly to knowing the state of the habitat, since it provides us with knowledge of the biological conditions of the ecosystem. Keywords: Coastal lagoons, onterpolation, Protected Natural Area, Gulf of Mexico, diversity, richness.

The fish community in Gulf of Mexico mangroves, a response to hydrological restoration

The present study evaluated the ecological response of fish fauna to hydrological restoration in a mangrove area in Terminos Lagoon in the Gulf of Mexico. In two years, environmental parameters and ichthyofauna were obtained in a channel under restoration and a conserved channel. The fish fauna was composed of 12 species. As a result of the restoration process, changes in composition and abundance of some species were detected. The presence of visiting marine species Bathygobius soporator and Eucinostomus melanopterus, and an increase in the abundance of resident fish, livebearers species, were recorded. Richness, diversity, and evenness vary significantly between channels. Generalized linear mixed models indicated that the abundances of resident and overall fishes were significantly related to water depth, temperature, and salinity. The results suggest that fish are an ecological indicator of the mangrove reconnection with the Terminos Lagoon and the restoration of natural tidal flow in the short term. Long-term systematic monitoring of fish fauna will promote a better understanding of the restoration of mangroves and corresponding changes in the function of this ecosystem.

Fish species richness in the Terminos Lagoon: An occurrence data compilation of four sampling campaigns along a multidecadal series

Here we present an occurrence dataset that contributes to the knowledge of tropical fish distribution in coastal habitats from the Terminos Lagoon Flora and Fauna Protection Area, one of the largest lagoon ecosystems in the Gulf of Mexico. Fish are high biomass keystone species in the Terminos Lagoon which provide socio-economic and ecosystem services. An initiative in 1980 was carried out to systematically sample the fish community of Terminos Lagoon for an annual cycle; the effectiveness of its results led to replicate in the lagoon the same sampling design for three more campaigns in 1998, 2010 and 2016. Constituted as a Flora and Fauna Protection Area in 1994, the Terminos Lagoon has received many efforts to inventory its biodiversity, particularly on the fish community since the 70s; however, these studies did not have consistent survey protocols, nor the longevity of the present study, which was over four decades. A total of 141 fish species, belonging to 90 genera, 49 families, 20 orders and two classes are presented in this study. Information on fish species occurrence data is provided corresponding to the Terminos Lagoon coastal ecosystem, southern Gulf of Mexico, assembled from four time periods at 1980, 1998, 2010 and 2016. The records form part of a consistently homogeneous database compilation, mostly derived from the research programme's sampled material on tropical fishery resources of the “Instituto de Ecologia, Pesquerias y Oceanografia del Golfo de Mexico (EPOMEX)”. The current dataset represents the first and most comprehensive online open-access source of information concerning the fish community occurring along and wide of the Terminos Lagoon ecosystem, with 1,249 data records and a total count of 48,717 organisms. Data are available through the Ocean Biodiversity Information System (OBIS).

The seasonal entrance of Penaeus setiferus and Penaeus duorarum postlarvae into Términos Lagoon, Campeche, México

This study establishes the season for the immigration (recruitment) of Penaeus setiferus and P. duorarum postlarvae into Términos Lagoon, México, as well as the hydrological conditions that occur during this event. The abundance of postlarvae of both species was used to infer the reproductive period for each species. The zooplankton collection was carried out monthly for three years. The nets used were 50 cm in diameter, 1.5 m in length and 505 μm mesh size, and temperature and salinity were measured with an YSI. The fluvial discharges were taken from Comisión Nacional del Agua (CONAGUA). The harmonic pattern variation (HPV) was analyzed for each variable (density of postlarvae, salinity, temperature and fluvial discharge). A cycle was analyzed and divided into two episodes (rise and descent) to estimate the HPV of each postlarval species. The entrance of both postlarval species starts from June to September, with higher density in August, which decreases from October to May, with the lowest density in March. The first episode was established from June to August and the second episode in September. During the first episode the hydrological conditions were: high salinity (34), a warm temperature (30ºC) and low accumulated fluvial discharge (2,828 m3 s-1), while, in the second, they were low salinity (28), a moderately warm temperature (29ºC) and high accumulated fluvial discharge (3,934 m3 s-1).

Geoacumulation of Heavy Metals in Sediment of the Fluvial–Lagoon–Deltaic System of the Palizada River, Campeche, Mexico

The fluvial–lagoon–deltaic system of the Palizada River in Campeche is an ecosystem of socioeconomic and ecological importance. It is justifiable to carry out studies in this system due to its connection with another larger ecosystem called the Términos Lagoon. The objective of this investigation was to analyze the concentration of Pb and Cd in sediments of the fluvial–lagoon–deltaic system of the Palizada River and to determine, with this, the contamination index of these metals. Cd showed the highest concentration in sampling sites and climatic seasons with respect to Pb, with a maximum value of 53.9 ± 5.0, while the Pb concentration was 10.4 ± 0.2 μg∙g−1. The same tendency was present with pollution and geoaccumulation indexes; here, the Cd index stands out. The enrichment of heavy metals was identified through the accumulation of Cd and Pb; such a process was evaluated through the geoacumulation index (Igeo). The results of this indicated that the contamination of these elements is mainly of anthropogenic origin. This element represents an ecological toxic risk due to the chronic presence of heavy metals in a priority area for the conservation of aquatic and terrestrial biota such as the Palizada system, owing to its high toxicity even at low concentrations. Thus, it is important to evaluate its sublethal effects in the organisms that inhabit this system, which requires the implementation of integral monitoring.