Summary
One of the ways to recognize patterns is through the intrinsic information of the object's shape by descriptors that allow us to quantitatively describe the contained shape of the object. In ...ichthyology, the otolith shape recognition is notable for each fish species, which allows the study of the sagitta otolith in species classification, the comparison of otolith shape across the fish ontogeny or growth, and the symmetry analysis of these structures in the case of the same fish. In the last twenty years, there has been a valuable contribution regarding otolith shape analysis and various types of morphometric descriptors have been proposed. The first objective of this work is to propose the implementation of invariant morphometric descriptors, as Discrete Compactness, Discrete Tortuosity, Non‐Circularity, and Mirror‐Symmetry, and compare their performance with other reported morphometric descriptors. The second objective is the implementation of the Random Forest (RF) algorithm to classify the fish species according their environment (marine, brackish, and freshwater). The right and left sagittae otoliths of 139 marine, brackish, and freshwater species (adults and juveniles) of the Yucatan peninsula and Gulf of Mexico were analysed with invariant and other reported descriptors. The global results show that the invariant descriptors can provide complementary information to other reported descriptors based on area or perimeter, given a low correlation between these features. The environment classification of species using a RF classifier showed that 83% of species correspond positively with their environment classification. This classification analysis can be a useful tool for studies of trophic dynamics, or in archaeological and paleontological studies on fossil fauna this classification tool would allow inferring from remains the environment of the studied communities and their evolution over long periods of time.
Coastal lagoons are systems that are dominated by the environmental variability caused by seasonal or diel cycles, with a direct effect on fish community composition. The aim of this study was to ...evaluate the species composition of the fish communities on 2 seasonal scales and analyze the diet composition of marine fish species that use the lagoon at some stage of their life cycles. The study took place in the Carbonera lagoon on the northern coast of Yucatán. Fishes were collected bimonthly (from December 2010 to October 2011) every 2 h using a beach seine net over 24-h cycles. Hydrologic variables and fish community composition were evaluated at nychthemeral and seasonal scales, and significant changes in temperature and salinity were observed. Species richness and diversity of fishes were higher during the night time, with marine species like pigfish (Orthopristis chrysoptera), silver perch (Bairdiella chrysoura), striped mojarra (Eugerres plumieri), and grunts (Haemulon plumieri). Abundance was highest during the daytime because of the presence of schools of juvenile herrings (Harengula clupeola) and residents species (Floridichthys polyommus and Fundulus persimilis). The diet composition of 10 juvenile marine species were analyzed, and four main trophic guilds (piscivores, detritivores, mollusk feeders, and zoobenthivores) were found. The juvenile marine species of commercial value that use the Carbonera lagoon for feeding purposes are mullets, herrings, and grunts. Thus, this system provides resources for juvenile species that are important in artisanal fisheries, and it is therefore very important to make management plans for its protection and conservation.
Climate change is currently considered one of the main phenomena affecting marine species through expansion or contraction of their distribution. Being ectothermic organisms, sharks of the family ...Carcharhinidae could be highly susceptible to the effects of climate change. These sharks are of great ecological importance, which is reflected in their role in the integrity of coastal and oceanic ecosystems as top predators that act to maintain the stability of the food chain, as well as providing economic value through fishing, consumption, and ecotourism. Currently, their populations are threatened by fishing pressure and anthropogenic activities, including meeting the demand for shark fins. Despite the ecological and economical importance of carcharhinid sharks, knowledge regarding how they are impacted by climate change remains scarce. Ecological niche modeling is a tool that allows analysis of future potential distributions under different climate change scenarios and could contribute to future planning activities and improved conservation outcomes for sharks. We generated models in Maxent in order to predict the potential geographic distribution of 25 carcharhinid sharks that inhabit Mexican waters, projecting this onto future climate change scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) to calculate the potential losses and gains in their distribution areas by the year 2050. The greatest shifts in suitable areas were observed for the sharks
Triaenodon obesus
(gained area) and
Carcharhinus porosus
(lost area). Overall, under all four RCP future scenarios, six species presented gains in suitable area and 19 species presented losses. The greatest loss of suitable area for carcharhinid sharks was found with RCP8.5; however, under this high-emissions global warming scenario, seven species actually showed an increase in distribution area. Our results therefore indicate that climate change could reduce suitable areas for most of the species by 2050. Assessment of the distribution of shark species under climate change is urgently required in order to prioritize conservation efforts toward the most vulnerable species and to ensure the natural function of marine ecosystems, thus maintaining the important ecosystem services they provide to human society.
Las lagunas costeras son sistemas dominados por la variabilidad ambiental ocasionada por ciclos estacionales o nictémeros, lo cual influye directamente en la composición de especies como la de los ...peces. El objetivo de este estudio fue evaluar la variación en la composición de la comunidad de peces a 2 escalas temporales y analizar la dieta de especies marinas que utilizan la laguna en alguna etapa de su ciclo de vida. El estudio se realizó en la laguna Carbonera en la costa norte de Yucatán, México. Se recolectaron peces cada 2 h con un chinchorro playero durante un ciclo de 24 h, en campañas bimestrales de diciembre de 2010 a octubre de 2011. Las variables hidrológicas registradas y la comunidad de peces se evaluaron a escala nictémera y estacional, y se observaron cambios significativos en la temperatura y la salinidad. La riqueza específica y la diversidad de peces fueron mayores durante la noche, cuando se registraron especies marinas como los armados (Orthopristis chrysoptera), las corvinas (Bairdiella chrysoura), las mojarras (Eugerres plumieri) y los roncos (Haemulon plumierii). La mayor abundancia se obtuvo durante las horas de luz debido a la presencia de cardúmenes de juveniles de sardina (Harengula clupeola) y especies residentes (Floridichthys polyommus y Fundulus persimilis). Se analizó la alimentación de 10 especies de peces marinos en estadio juvenil, y se identificaron 4 principales gremios tróficos (piscívoros, detritívoros, malacófagos y zoobentófagos). Las especies marinas en estadio juvenil de importancia comercial que utilizan la laguna Carbonera para alimentación son las lisas, las sardinas y los roncos. Por lo tanto, este sistema brinda recursos a juveniles de especies de gran importancia para la pesca artesanal, por lo que es de suma importancia elaborar estrategias de manejo para su protección y conservación.
Mangroves are unique coastal ecosystems, which have many important ecological functions, as they are a reservoir of many marine species well adapted to saline conditions and are fundamental as sites ...of carbon storage. Although the microbial contribution to nutrient cycling in these ecosystems has been well recognized, there is a lack of information regarding the microbial composition and structure of different ecological types of mangrove forests. In this study, we characterized the microbial community (Bacteria and Archaea) in sediments associated with five ecological types of mangrove forests in a coastal lagoon dominated by
and
, through 16S rRNA-V4 gene sequencing. Overall, Proteobacteria (51%), Chloroflexi (12%), Gemmatimonadetes (5%) and Planctomycetes (6%) were the most abundant bacterial phyla, while Thaumarchaeota (30%), Bathyarchaeota (21%) and Nanoarchaeaeota (18%) were the dominant archaeal phyla. The microbial composition associated with basin mangroves dominated by
was significantly different from the other ecological types, which becomes relevant for restoration strategies.
The deviation of expected relationships between taxonomic (TD), phylogenetic (PD), and functional (FD) diversity may inform about some processes (speciation, extinction, competition, and migration) ...responsible for current biodiversity patterns. We studied the relationship between different dimensions of bird diversity (TD, PD, and FD) of the Yucatan Peninsula (YP) in a context of future climate change. We used ecological niche models to predict the current and future potential distribution of 257 bird species of the YP and estimate their TD, PD, and FD. We calculated a standardized effect size of PD (SES.PD) and FD (SES.FD) to provide an estimation of phylogenetic and functional diversity, independent from species richness. Finally, we evaluated the effectiveness of the system of PAs comparing the observed diversity values in each PA versus what is expected for a null model. We found a positive correlation between PD and TD, and a negative correlation between FD and TD in the current and future scenarios. Finally, we found that none of the PAs protect more diversity of birds than expected by a null model. Our results suggest that macroevolutionary processes have played an important role in the composition of the current Yucatan Peninsula avian assemblages. Our assessment of the effectiveness of the PAs suggests the need to adopt an integrative approach to biodiversity conservation in the YP.
Several species of the genus Fundulus survive in environments highly impacted by human activities. When fish are exposed to environmental stress conditions, the expression of enzyme cytochrome P4501A ...is induced. The capacity of fish to adapt to environmental conditions could influence their survival and distribution. We evaluate the gene expression of CYP4501A in two endemic Fundulus species from Chelem Lagoon (22 individuals of Fundulus grandissimus and 31 of Fundulus persimilis) and Carbonera Lagoon (12 individuals of F. persimilis), both located in the north coast of the Yucatan Peninsula. Individuals of F. grandissmus exhibit higher expression values compared to F. persimilis. A statistically significant difference was detected in CYP4501A gene expression between populations of F. persimilis in Chelem Lagoon and between lagoons, possibly induced by environmental conditions. We also found Glucocorticoid Response Elements (GRE) in the sequences of the regulatory region of the CYP4501A gene. GRE act as glucocorticoid recognition sites, which regulate the expression of CYP enzymes. F. grandissimus individuals with higher expression levels exhibit a mutation in a GRE site, affecting the regulation of CYP enzymes inducing overexpression. Our results suggest that gene expression of CYP enzymes is induced by environmental conditions and also affects the function of their regulatory GRE sites.
The epidemiologic transition in Mexico has generated a change of paradigm in public health. Morbidity is characterized by infectious diseases and the mortality is due to chronic degenerative ...diseases. The three most important infectious diseases in the country are: respiratory infections, diarrhea, and urinary tract infections.
The objective of this work was to build a tool to monitor the presence of health risks in the environment in a timely manner and to demonstrate its application in different sicknesses, especially those that are water related. In this study, we analyzed water samples from five cenotes with high tourist flow in the State of Yucatan. We developed a DNA microarray for the adequate and prompt detection of viruses, bacteria, fungi, and parasites. This microarray could be used in samples of different origin including air, water (fresh, brackish and saltwater), food, inert surfaces or wounds. Clinically, it would allow prompt and precise detection of etiological agents of infectious diseases to prevent outbreaks. It would also be useful for the identification of those agents that cannot be detected in our laboratories with the traditional methods. It includes 38,000 probes that detect 252 etiological agents of diseases in humans and antimicrobial resistance genes. Results from DNA samples can be obtained in 24 h, which would be difficult or impossible using other technologies.
The results are readily available within 24 h. Samples from five cenotes (sinkholes) with high flow of people, were analyzed with the microarray. The water samples analyzed detected 228 different bacteria, viruses, fungi, and protozoa. They are amongst the most important etiological agents for infectious diseases in Mexico.
The microarray provides the opportunity for precise and early detection of various infectious agents in individuals, hospitals and natural environments. This could help reduce the global burden of diseases, the severity of outbreaks, and reduce antibiotic resistance.
Many species of marine fish use coastal lagoons during early stages of their life cycles due to the protection provided by their turbid waters and complex structure of the environment, such as ...mangroves and mudflats, and the availability of food derived from the high productivity of these sites. In this study, we analyzed the diet of six species of juvenile marine fishes that use a karstic lagoon system in the northwest portion of the Yucatan Peninsula, Mexico. Through stomach contents analysis we determined the trophic differences among Caranx latus, Oligoplites saurus, Trachinotus falcatus, Synodus foetens, Lutjanus griseus, and Strongylura notata. C. latus, O. saurus, S. foetens, and S. notate, which are ichthyophagous species (>80% by number). L. griseus feeds mainly on crustaceans (>55%) and fish (35%), while T. falcatusfeeds on mollusks (>50% bivalves, >35% gastropods). The analysis of similarities (ANOSIM) showed differences in the diet of all species. Cluster analysis, based on the Bray-Curtis similarity matrix revealed three groups; one characterized by the ichthyophagous guild (S. notata, S. foetens, C. latus, and O. saurus), other group formed by the crustacean consumers (L. griseus), and the third, composed by the mollusk feeder (T. falcatus). Species of the ichthyophagous guild showed overlap in their diets, which under conditions of low prey abundance may trigger competition, hence affecting juvenile stages of these marine species that use coastal lagoons to feed and grow.
This study evaluated the response of bat communities, from a taxonomic and functional perspective, to variation in the vegetation and landscape attributes produced by anthropogenic activities. We ...characterized the following: (1) the community of phyllostomid and mormoopid bats associated with the initial successional stages of a tropical dry forest, (2) the response of these communities to the variation in the attributes of the vegetation and the landscape, and (3) how the seasonality modulates such response. This allowed us to identify potential mechanisms underlying the response of bat communities to human disturbance. Our results showed that the species negatively affected by the anthropoghenic disturbance are those with greater body mass, larger nose-leaves, or a lower wing aspect ratio and relative wing loading, which perform low-speed flights and have high maneuverability and, potentially, a high directionality in their emissions. We also detected a greater sensitivity of bats to changes in the landscape attributes regarding the riparian than the dry forest, and that the effect of anthropic transformation on bats was intensified during the dry season. Then, the continued loss of the original vegetation can lead to a loss of certain groups of bat species in neotropical landscapes, reducing the resilience of the system.
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