Analytical Characterization of Heterogeneities in mRNA-Lipid Nanoparticles Using Sucrose Density Gradient Ultracentrifugation.

Rational design and robust formulation processes are critical for optimal delivery of mRNA by lipid nanoparticles (LNPs). Varying degrees of heterogeneity in mRNA-LNPs can affect their biophysical and functional properties. Given the profound complexity of mRNA-LNPs, it is critical to develop comprehensive and orthogonal analytical techniques for a better understanding of these formulations. To this end, we developed a robust ultracentrifugation method for density-based separation of subpopulations of mRNA-LNPs. Four LNP formulations encapsulating human erythropoietin (hEPO) with varying functionalities were synthesized using two ionizable lipids, A and B, and two helper lipids, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and 1,2-dierucoyl-sn-glycero-3-phosphoethanolamine (DEPE), along with cholesterol and DMG-PEG-2K. Upon ultracentrifugation on a sucrose gradient, a distinct pattern of "fractions" was observed across the gradient, from the less dense topmost fraction to the increasingly denser bottom fractions, which were harvested for comprehensive analyses. Parent LNPs, A-DOPE and B-DOPE, were resolved into three density-based fractions, each differing significantly in the hEPO expression following intravenous and intramuscular routes of administration. Parent B-DEPE LNPs resolved into two density-based fractions, with most of the payload and lipid content being attributed to the topmost fraction compared to the lower one, indicating some degree of heterogeneity, while parent A-DEPE LNPs showed remarkable homogeneity, as indicated by comparable in vivo potency, lipid numbers, and particle count among the three density-based fractions. This study is the first to demonstrate the application of density gradient-based ultracentrifugation (DGC) for a head-to-head comparison of heterogeneity as a function of biological performance and biophysical characteristics of parent mRNA-LNPs and their subpopulations.

Bellwethers of change: population modelling of North Pacific humpback whales from 2002 through 2021 reveals shift from recovery to climate response.

For the 40 years after the end of commercial whaling in 1976, humpback whale populations in the North Pacific Ocean exhibited a prolonged period of recovery. Using mark-recapture methods on the largest individual photo-identification dataset ever assembled for a cetacean, we estimated annual ocean-basin-wide abundance for the species from 2002 through 2021. Trends in annual estimates describe strong post-whaling era population recovery from 16 875 (± 5955) in 2002 to a peak abundance estimate of 33 488 (± 4455) in 2012. An apparent 20% decline from 2012 to 2021, 33 488 (± 4455) to 26 662 (± 4192), suggests the population abruptly reached carrying capacity due to loss of prey resources. This was particularly evident for humpback whales wintering in Hawai'i, where, by 2021, estimated abundance had declined by 34% from a peak in 2013, down to abundance levels previously seen in 2006, and contrasted to an absence of decline in Mainland Mexico breeding humpbacks. The strongest marine heatwave recorded globally to date during the 2014-2016 period appeared to have altered the course of species recovery, with enduring effects. Extending this time series will allow humpback whales to serve as an indicator species for the ecosystem in the face of a changing climate.

Uncovering the dominant role of root metabolism in shaping rhizosphere metabolome under drought in tropical rainforest plants.

Plant-soil-microbe interactions are crucial for driving rhizosphere processes that contribute to metabolite turnover and nutrient cycling. With the increasing frequency and severity of water scarcity due to climate warming, understanding how plant-mediated processes, such as root exudation, influence soil organic matter turnover in the rhizosphere is essential. In this study, we used 16S rRNA gene amplicon sequencing, rhizosphere metabolomics, and position-specific 13C-pyruvate labeling to examine the effects of three different plant species (Piper auritum, Hibiscus rosa sinensis, and Clitoria fairchildiana) and their associated microbial communities on soil organic carbon turnover in the rhizosphere. Our findings indicate that in these tropical plants, the rhizosphere metabolome is primarily shaped by the response of roots to drought rather than direct shifts in the rhizosphere bacterial community composition. Specifically, the reduced exudation of plant roots had a notable effect on the metabolome of the rhizosphere of P. auritum, with less reliance on neighboring microbes. Contrary to P. auritum, H. rosa sinensis and C. fairchildiana experienced changes in their exudate composition during drought, causing alterations to the bacterial communities in the rhizosphere. This, in turn, had a collective impact on the rhizosphere's metabolome. Furthermore, the exclusion of phylogenetically distant microbes from the rhizosphere led to shifts in its metabolome. Additionally, C. fairchildiana appeared to be associated with only a subset of symbiotic bacteria under drought conditions. These results indicate that plant species-specific microbial interactions systematically change with the root metabolome. As roots respond to drought, their associated microbial communities adapt, potentially reinforcing the drought tolerance strategies of plant roots. These findings have significant implications for maintaining plant health and preference during drought stress and improving plant performance under climate change.

Drought re-routes soil microbial carbon metabolism towards emission of volatile metabolites in an artificial tropical rainforest.

Drought impacts on microbial activity can alter soil carbon fate and lead to the loss of stored carbon to the atmosphere as CO2 and volatile organic compounds (VOCs). Here we examined drought impacts on carbon allocation by soil microbes in the Biosphere 2 artificial tropical rainforest by tracking 13C from position-specific 13C-pyruvate into CO2 and VOCs in parallel with multi-omics. During drought, efflux of 13C-enriched acetate, acetone and C4H6O2 (diacetyl) increased. These changes represent increased production and buildup of intermediate metabolites driven by decreased carbon cycling efficiency. Simultaneously,13C-CO2 efflux decreased, driven by a decrease in microbial activity. However, the microbial carbon allocation to energy gain relative to biosynthesis was unchanged, signifying maintained energy demand for biosynthesis of VOCs and other drought-stress-induced pathways. Overall, while carbon loss to the atmosphere via CO2 decreased during drought, carbon loss via efflux of VOCs increased, indicating microbially induced shifts in soil carbon fate.

MetaboDirect: an analytical pipeline for the processing of FT-ICR MS-based metabolomic data.

BACKGROUND: Microbiomes are now recognized as the main drivers of ecosystem function ranging from the oceans and soils to humans and bioreactors. However, a grand challenge in microbiome science is to characterize and quantify the chemical currencies of organic matter (i.e., metabolites) that microbes respond to and alter. Critical to this has been the development of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), which has drastically increased molecular characterization of complex organic matter samples, but challenges users with hundreds of millions of data points where readily available, user-friendly, and customizable software tools are lacking. RESULTS: Here, we build on years of analytical experience with diverse sample types to develop MetaboDirect, an open-source, command-line-based pipeline for the analysis (e.g., chemodiversity analysis, multivariate statistics), visualization (e.g., Van Krevelen diagrams, elemental and molecular class composition plots), and presentation of direct injection high-resolution FT-ICR MS data sets after molecular formula assignment has been performed. When compared to other available FT-ICR MS software, MetaboDirect is superior in that it requires a single line of code to launch a fully automated framework for the generation and visualization of a wide range of plots, with minimal coding experience required. Among the tools evaluated, MetaboDirect is also uniquely able to automatically generate biochemical transformation networks (ab initio) based on mass differences (mass difference network-based approach) that provide an experimental assessment of metabolite connections within a given sample or a complex metabolic system, thereby providing important information about the nature of the samples and the set of microbial reactions or pathways that gave rise to them. Finally, for more experienced users, MetaboDirect allows users to customize plots, outputs, and analyses. CONCLUSION: Application of MetaboDirect to FT-ICR MS-based metabolomic data sets from a marine phage-bacterial infection experiment and a Sphagnum leachate microbiome incubation experiment showcase the exploration capabilities of the pipeline that will enable the research community to evaluate and interpret their data in greater depth and in less time. It will further advance our knowledge of how microbial communities influence and are influenced by the chemical makeup of the surrounding system. The source code and User's guide of MetaboDirect are freely available through ( https://github.com/Coayala/MetaboDirect ) and ( https://metabodirect.readthedocs.io/en/latest/ ), respectively. Video Abstract.

Paper wasps form abstract concept of 'same and different'.

Concept formation requires animals to learn and use abstract rules that transcend the characteristics of specific stimuli. Abstract concepts are often associated with high levels of cognitive sophistication, so there has been much interest in which species can form and use concepts. A key abstract concept is that of sameness and difference, where stimuli are classified as either the same as or different than an original stimulus. Here, we used a simultaneous two-item same-different task to test whether paper wasps (Polistes fuscatus) can learn and apply a same-different concept. We trained wasps by simultaneously presenting pairs of same or different stimuli (e.g. colours). Then, we tested whether wasps could apply the concept to new stimuli of the same type (e.g. new colours) and to new stimulus types (e.g. odours). We show that wasps learned a general concept of sameness or difference and applied it to new samples and types of stimuli. Notably, wasps were able to transfer the learned rules to new stimuli in a different sensory modality. Therefore, P. fuscatus can classify stimuli based on their relationships and apply abstract concepts to novel stimulus types. These results indicate that abstract concept learning may be more widespread than previously thought.

Genome Sequences of Novel Iflaviruses in the Gray Lawn Leafhopper, an Experimental Vector of Corn Stunt Spiroplasma.

Two novel iflaviruses were detected in the metatranscriptome of the gray lawn leafhopper, Exitianus exitiosus (Uhler). The assembled genome sequence of Exitianus exitiosus virus 1 was 9,858 nucleotides (nt) long and encodes a 3,083-amino acid (aa) polyprotein. Exitianus exitiosus virus 2 was 10,219 nt long and encodes a 2,947-aa polyprotein.

Color scrambles reveal red and green half-wave linear mechanisms plus a mechanism selective for low chromatic contrast.

This paper introduces a new method to determine how subjects make discriminations among red-green texture stimuli. More specifically, the method determines (1) the number of mechanisms in human vision sensitive to lights that vary along the constant-S cardinal axis (cSCA) of DKL space and (2) the sensitivity of each mechanism to cSCA lights. Each of five subjects was tested in four, separately-blocked tasks. In each task, the subject strove to detect the location of a patch of cSCA-scramble (a spatially random mixture of cSCA lights) in a large, annular background of cSCA-scramble with a different histogram. In different tasks the target patch was (1) redder, (2) greener, (3) higher in red-green contrast, and (4) lower in red-green contrast than the background. For each subject in each task, we measure how target salience is influenced by different cSCA lights. By assuming that in each task each subject uses a weighted sum of his-or-her available mechanisms to construct a "tool" that is optimal for detecting the target, we can derive the sensitivity functions of the mechanisms underlying performance. Results suggest that human vision possesses three mechanisms sensitive to cSCA lights: a red half-wave linear mechanism, a complementary green half-wave linear mechanism, and a third mechanism that is activated by color-scrambles with low chromatic contrast in high-chromatic-contrast backgrounds.

Effect of food source availability in the salivary gland transcriptome of the unique burying beetle Nicrophorus pustulatus (Coleoptera: Silphidae).

Nicrophorus is a genus of beetles that bury and transform small vertebrate carcasses into a brood ball coated with their oral and anal secretions to prevent decay and that will serve as a food source for their young. Nicrophorus pustulatus is an unusual species with the ability to overtake brood of other burying beetles and whose secretions, unlike other Nicrophorus species, has been reported not to exhibit antimicrobial properties. This work aims to better understand how the presence or absence of a food source influences the expression of genes involved in the feeding process of N. pustulatus. To achieve that, total RNA was extracted from pooled samples of salivary gland tissue from N. pustulatus and sequenced using an Illumina platform. The resulting reads were used to assemble a de novo transcriptome using Trinity. Duplicates with more than 95% similarity were removed to obtain a "unigene" set. Annotation of the unigene set was done using the Trinotate pipeline. Transcript abundance was determined using Kallisto and differential gene expression analysis was performed using edgeR. A total of 651 genes were found to be differentially expressed, including 390 upregulated and 261 downregulated genes in fed insects compared to starved. Several genes upregulated in fed beetles are associated with the insect immune response and detoxification processes with only one transcript encoding for the antimicrobial peptide (AMP) defensin. These results confirm that N. pustulatus does not upregulate the production of genes encoding AMPs during feeding. This study provides a snapshot of the changes in gene expression in the salivary glands of N. pustulatus following feeding while providing a well described transcriptome for the further analysis of this unique burying beetle.

Pathological evidence in Plicopurpura pansa associated with the stranding of a bulk carrier ship during Hurricane "Patricia" in the Mexican Central Pacific.

Due to the effects of Hurricane Patricia (2015), the bulk freighter "El Llanitos" ran aground in the rocky intertidal zone of Colima, Mexico. We assessed the impact of this ship's stranding on a population of the gastropod Plicopurpura pansa. Toxic elements, hydrocarbons, shell deformities, presence of tumors, imposex, and morphological relationships were analyzed. Two years after the stranding occurred, high cyanide concentrations (0.0363 mg/l) and Ni concentrations above permissible limits (3.35 mg/l) were found in surface seawater. Hydrocarbon concentrations were high in the aft zone of the ship and decreased towards the bow area of the freighter. The P. pansa specimens collected closest to the ship structure presented a high prevalence of tumorations in the structure of the foot and morphological anomalies in the shell structure; imposex was 32% and there was evidence of effects on the growth indicator. The evidence presented here supports the existence of a significant impact from the grounding of the ship on a protected gastropod species associated with the rocky intertidal zone on the coast of Colima. The potential of P. pansa as a bioindicator species of pollution caused by toxic elements and hydrocarbons associated with stranding events in the tropical Pacific is documented.

Intended or Unintended Doping? A Review of the Presence of Doping Substances in Dietary Supplements Used in Sports.

INTRODUCTION: The use of dietary supplements is increasing among athletes, year after year. Related to the high rates of use, unintentional doping occurs. Unintentional doping refers to positive anti-doping tests due to the use of any supplement containing unlisted substances banned by anti-doping regulations and organizations, such as the World Anti-Doping Agency (WADA). The objective of this review is to summarize the presence of unlabeled doping substances in dietary supplements that are used in sports. METHODOLOGY: A review of substances/metabolites/markers banned by WADA in ergonutritional supplements was completed using PubMed. The inclusion criteria were studies published up until September 2017, which analyzed the content of substances, metabolites and markers banned by WADA. RESULTS: 446 studies were identified, 23 of which fulfilled all the inclusion criteria. In most of the studies, the purpose was to identify doping substances in dietary supplements. DISCUSSION: Substances prohibited by WADA were found in most of the supplements analyzed in this review. Some of them were prohormones and/or stimulants. With rates of contamination between 12 and 58%, non-intentional doping is a point to take into account before establishing a supplementation program. Athletes and coaches must be aware of the problems related to the use of any contaminated supplement and should pay special attention before choosing a supplement, informing themselves fully and confirming the guarantees offered by the supplement.

Feasibility Study of an Optical Caustic Plasmonic Light Scattering Sensor for Human Serum Anti-Dengue Protein E Antibody Detection.

Antibody detection and accurate diagnosis of tropical diseases is essential to help prevent the spread of disease. However, most detection methods lack cost-effectiveness and field portability, which are essential features for achieving diagnosis in a timely manner. To address this, 3D-printed oblate spheroid sample chambers were fabricated to measure green light scattering of gold nanoparticles using an optical caustic focus to detect antibodies. Scattering signals of 20-200 nm gold nanoparticles using a green laser were compared to green light emitting diode (LED) light source signals and to Mie theory. The change in signal from 60 to 120 nm decreased in the order of Mie Theory > optical caustic scattering > 90° scattering. These results suggested that conjugating 60 nm gold nanoparticles and using an optical caustic system to detect plasmonic light scattering, would result in a sensitive test for detecting human antibodies in serum. Therefore, we studied the light scattering response of conjugated gold nanoparticles exposed to different concentrations of anti-protein E antibody, and a feasibility study of 10 human serum samples using dot blot and a handheld optical caustic-based sensor device. The overall agreement between detection methods suggests that the new sensor concept shows promise to detect gold nanoparticle aggregation in a homogeneous assay. Further testing and protocol optimization is needed to draw conclusions on the positive and negative predictive values for this new testing system.

Streptozocin-induced type-1 diabetes mellitus results in decreased density of CGRP sensory and TH sympathetic nerve fibers that are positively correlated with bone loss at the mouse femoral neck.

Type-1 diabetes mellitus (T1DM) results in loss of innervation in some tissues including epidermis and retina; however, the effect on bone innervation is unknown. Likewise, T1DM results in pathological bone loss and increased risk of fracture. Thus, we quantified the density of calcitonin gene-related peptide (CGRP+) sensory and tyrosine hydroxylase (TH+) sympathetic nerve fibers and determined the association between the innervation density and microarchitecture of trabecular bone at the mouse femoral neck. Ten weeks-old female mice received 5 daily administrations of streptozocin (i.p. 50mg/kg) or citrate (control group). Twenty weeks later, femurs were analyzed by microCT and processed for immunohistochemistry. Confocal microscopy analysis revealed that mice with T1DM had a significant loss of both CGRP+ and TH+ nerve fibers in the bone marrow at the femoral neck. Likewise, microCT analysis revealed a significant decrease in the trabecular bone mineral density (tBMD), bone volume/total volume ratio (BV/TB), trabecular thickness (Tb.Th), trabecular number (Tb.N) and trabecular separation (Tb.Sp) in mice with T1DM as compared to control mice. Analysis of correlation revealed a positive and significant association between density of CGRP+ or TH+ nerve fibers with tBMD, BV/TV, Tb.Th and Tb.Sp, but not with trabecular number (there was a positive association only for CGRP+) and degree of anisotropy (DA). This study suggests an interaction between sensory and sympathetic nervous system and T1DM-induced bone loss. Identification of the factors involved in the loss of CGRP+ sensory and TH+ sympathetic fibers and how they regulate bone loss may result in new avenues to treat T1DM-related osteoporosis.

Bi- and uniciliated ependymal cells define continuous floor-plate-derived tanycytic territories.

Multiciliated ependymal (E1) cells line the brain ventricles and are essential for brain homeostasis. We previously identified in the lateral ventricles a rare ependymal subpopulation (E2) with only two cilia and unique basal bodies. Here we show that E2 cells form a distinct biciliated epithelium extending along the ventral third into the fourth ventricle. In the third ventricle floor, apical profiles with only primary cilia define an additional uniciliated (E3) epithelium. E2 and E3 cells' ultrastructure, marker expression and basal processes indicate that they correspond to subtypes of tanycytes. Using sonic hedgehog lineage tracing, we show that the third and fourth ventricle E2 and E3 epithelia originate from the anterior floor plate. E2 and E3 cells complete their differentiation 2-3 weeks after birth, suggesting a link to postnatal maturation. These data reveal discrete bands of E2 and E3 cells that may relay information from the CSF to underlying neural circuits along the ventral midline.

Floating Marine Debris in waters of the Mexican Central Pacific.

The presence of marine debris has been reported recently in several oceans basins; there is very little information available for Mexican Pacific coasts, however. This research examined the composition, possible sources, distribution, and density of Floating Marine Debris (FMD) during nine research surveys conducted during 2010-2012 in the Mexican Central Pacific (MCP). Of 1820 floating objects recorded, 80% were plastic items. Sources of FMD were determined using key objects, which indicated that the most were related to the presence of the industrial harbor and of a growing fishing industry in the study area. Densities were relatively high, ranging from 40 to 2440objects/km2; the highest densities were recorded in autumn. FMD were distributed near coastal regions, mainly in Jalisco, influenced by river outflow and surface currents. Our results seem to follow worldwide trends and highlight the need for further studies on potential ecological impacts within coastal waters of the MCP.

Melanin granules melanophages and a fully-melanized epidermis are common traits of odontocete and mysticete cetaceans.

BACKGROUND: The cellular mechanisms used to counteract or limit damage caused by exposure of marine vertebrates to solar ultraviolet (UV) radiation are poorly understood. Cetaceans are vulnerable because they lack protective skin appendages and are obliged to surface continuously to breathe, thus being exposed repeatedly to UV light. Although molecular mechanisms of photoprotection of cetaceans have been studied, there is limited knowledge about their epidermal structure and photoprotective effectors. OBJECTIVE: To describe and compare the epidermis of mysticete and odontocete cetaceans and identify potentially photoprotective traits. ANIMALS: Twenty eight free-living individuals belonging to six cetacean species were sampled in the Mexican Central Pacific and Gulf of California. Species sampled were the bottlenose dolphin, pantropical spotted dolphin, spinner dolphin, Bryde's whale, fin whale and humpback whale. METHODS: Histological and cytological evaluation of skin biopsy tissue collected in the field between 2014 and 2016. RESULTS: All cetaceans had only three epidermal layers, lacking both the stratum granulosum and stratum lucidum. A relatively thick stratum corneum with a parakeratosis-like morphology was noted. Melanin was observed within keratinocytes in all epidermal layers, including the stratum corneum and apical melanin granules obscured the keratinocyte nucleus. Keratinocytes had a perinuclear halo. Keratinocyte diameter differed between cetacean suborders and amongst species. Melanophage clusters were common in most cetacean species. CONCLUSIONS: The widespread presence of melanin and the unexpectedly high number of melanophages may constitute a unique photoprotective trait of cetaceans and could reflect primitive adaptations to their environment and to their obligate marine-bound life.

Isotopic effects of different preservation methods on scales of olive ridley sea turtles (Lepidochelys olivacea) from the Mexican Central Pacific.

RATIONALE: Stable isotope analysis can be used to obtain information on olive ridley sea turtles in the Mexican Central Pacific (MCP). Tissue samples such as scale, muscle, and blood are usually not analyzed immediately and are preserved in different substances such as ethanol, formalin, sodium chloride, the ideal being liquid nitrogen. Due to logistical reasons, the latter preservation method cannot always be used. The objective of the present study was to evaluate the efficiency of dimethyl sulfoxide (DMSO) as a preservation agent for later stable isotope analysis. METHODS: Forty-eight paired scale samples of olive ridley were collected in MCP waters and preserved in DMSO and liquid nitrogen. We determined their δ13 C and δ15 N values using a Carlo Erba 1108 elemental analyzer coupled to a ThermoFinnigan Delta Plus XP isotope ratio mass spectrometer (precision ±0.2‰ for each stable isotope). The mean isotopic ratios of each preservation method were compared. RESULTS: Significant differences were observed between the isotopic ratios of samples in the two preservatives. Samples preserved in DMSO resulted in more negative isotopic values than those in liquid nitrogen, and a correction factor was calculated. The correction factors were 2.1‰ for δ13 C values and 0.8‰ for δ15 N values. CONCLUSIONS: DMSO is not equivalent to liquid nitrogen for the preservation of olive ridley scales to be used for isotopic analysis. If DMSO has to be used for logistical reasons a replicate sample should also be collected to be able to estimate a correction factor. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of terrestrial runoff on the coral communities in Santiago Bay, Colima, Mexican Pacific Coast

Abstract:Coral reef ecosystems are under stress of different origins, from factors including sedimentation, fragmentation, overfishing, and tourism, depending on their geographical location, depth, and proximity to recreation areas. In this study of Juluapan Lagoon, we examined the relationship between various water-quality attributes and the status indicators of the coral community at La Boquita reef. During 2011 (12 months of sampling), six monitoring stations in the Juluapan lagoon were established in order to observe the gradient of the distribution of the physicochemical parameters: three stations on the upper part, or BI, (S4 to S6) and three more in the lower part, or BII, (S1 to S3). A control station (CS) was located in the coral reef close to the lagoon channel, and where dissolved inorganic nutrients and cellular carbon content were determined. Additionally, we considered the monitoring of three of the eight largest coral structures/headlands of this community: the first was the station closest to the channel communicating with Juluapan lagoon (C1), the second was in the intermediate region with respect to that lagoon (C2), and the third was farthest from the channel (C3). Three line intercept transects (LIT) 30 m in length and perpendicular to the coast provenance were established in each station, and the parameters indicative of the status of corals were evaluated in an area of 60 m2 on each transect (180 m2 by the station). Turbidity, evidence of fishing, signs of settling, algal coverage, abundance of fish, rate of sediment, and coral health records (as for CoralWach chart) were determined in situ and from digital photographs and videos. Considering various community status indicators used in the reef area, we could recognize a state of general deterioration, which was reflected in the loss of 17% of coral coverage. The main anthropogenic disturbances in adjacent areas to La Boquita reef included wastewater discharges into the lagoon, tourist developments in the coastal zone, deforestation and erosion resulting from inappropriate development, and the runoff of nutrients from agricultural lands nearby the lagoon. All these significantly contributed to the nutrient-enriched waters of the lagoon, especially in summer, with negative effects on the coral community. Continued exposure to these factors, coupled with the lack of control over other anthropogenic components, has promoted the maintenance of a chronic stress state in the studied coral community. Our findings highlight the need for the development of appropriate coastal management and conservation policies for the coral reefs of the Mexican Pacific Coast. Rev. Biol. Trop. 64 (3): 1185-1200. Epub 2016 September 01.

ResumenDependiendo de la ubicación geográfica, la profundidad, y la proximidad a zonas de recreo, algunos arrecifes de coral están bajo estrés por factores que incluyen la sedimentación, la fragmentación, la sobrepesca y el turismo. En la presente investigación, se estudian los diferentes atributos de calidad de agua de la Laguna Juluapan e indicadores del estatus de la comunidad coralina La Boquita. Durante 2011 (12 meses de muestreo), seis estaciones de monitoreo fueron establecidas dentro de la laguna de Juluapan, a fin de observar el gradiente de distribución de los parámetros fisicoquímicos: tres estaciones en la parte interna ó B1, (S4 a S6), y tres en la parte más externa, ó B2 (S1 a S3); una estación control (CS) fue ubicada en la zona coralina cercana a la comunicación con la Laguna de Juluapan, fueron determinados nutrientes inorgánicos disueltos y contenido de carbono celular. Adicionalmente se realizó el monitoreo de tres de los ocho cabezales coralinos que conforman esta comunidad. El primero de ellos fue localizado en la cercanía de la intercomunicación con la Laguna Juluapan (C1), el segundo en la región intermedia respecto a la proximidad de dicho cuerpo lagunar (C2), y el tercero totalmente alejado respeto a la intercomunicación (C3). En cada estación fueron colocadas, tres líneas de transectos de intersección (LIT) de 30 m de longitud de forma perpendicular al perfil de la costa, a partir de ello, fueron evaluados diversos parámetros de la condición coralina, cubriendo un área de 60 m2 en cada transecto (180 m2 por estación). En cada área de transecto fue evaluada la turbidez, evidencias de daños por pesca, daños por sedimentación, cobertura de algas, abundancia de peces, tasa de sedimentación, además de obtenerse registros de la salud coralina usando como indicador la tarjeta CoralWatch in situ, a partir de tomas fotográficas y videos. Considerando los diferentes indicadores del estatus de la comunidad coralina estudiada, nosotros pudimos reconocer un estado general de deterioro, reflejado en la pérdida del 17% de la cobertura de coral. Las principales alteraciones antropogénicas en las zonas adyacentes al arrecife La Boquita corresponde a descargas de aguas residuales en la laguna, desarrollos turísticos en la zona costera, la deforestación y efecto erosivo asociado al desarrollo urbano inadecuado, así como el escurrimiento de nutrientes de tierras agrícolas alrededor de la laguna. Estos factores contribuyen de manera significativa al enriquecimiento de nutrientes a la laguna, sobre todo en verano, con efectos negativos sobre la comunidad de coral. La exposición continua a estos factores, junto con la falta de control sobre otros componentes antropogénicos, promueve la existencia de un estado de estrés crónico en la comunidad coralina estudiada. Nuestros resultados destacan la necesidad de implementar políticas apropiadas de conservación para los arrecifes coralinos de la costa del Pacífico mexicano.

Effects of terrestrial runoff on the coral communities in Santiago Bay, Colima, Mexican Pacific Coast.

Coral reef ecosystems are under stress of different origins, from factors including sedimentation, fragmentation, overfishing, and tourism, depending on their geographical location, depth, and proximity to recreation areas. In this study of Juluapan Lagoon, we examined the relationship between various water-quality attributes and the status indicators of the coral community at La Boquita reef. During 2011 (12 months of sampling), six monitoring stations in the Juluapan lagoon were established in order to observe the gradient of the distribution of the physicochemical parameters: three stations on the upper part, or BI, (S4 to S6) and three more in the lower part, or BII, (S1 to S3). A control station (CS) was located in the coral reef close to the lagoon channel, and where dissolved inorganic nutrients and cellular carbon content were determined. Additionally, we considered the monitoring of three of the eight largest coral structures/headlands of this community: the first was the station closest to the channel communicating with Juluapan lagoon (C1), the second was in the intermediate region with respect to that lagoon (C2), and the third was farthest from the channel (C3). Three line intercept transects (LIT) 30 m in length and perpendicular to the coast provenance were established in each station, and the parameters indicative of the status of corals were evaluated in an area of 60 m2 on each transect (180 m2 by the station). Turbidity, evidence of fishing, signs of settling, algal coverage, abundance of fish, rate of sediment, and coral health records (as for CoralWach chart) were determined in situ and from digital photographs and videos. Considering various community status indicators used in the reef area, we could recognize a state of general deterioration, which was reflected in the loss of 17 % of coral coverage. The main anthropogenic disturbances in adjacent areas to La Boquita reef included wastewater discharges into the lagoon, tourist developments in the coastal zone, deforestation and erosion resulting from inappropriate development, and the runoff of nutrients from agricultural lands nearby the lagoon. All these significantly contributed to the nutrient-enriched waters of the lagoon, especially in summer, with negative effects on the coral community. Continued exposure to these factors, coupled with the lack of control over other anthropogenic components, has promoted the maintenance of a chronic stress state in the studied coral community. Our findings highlight the need for the development of appropriate coastal management and conservation policies for the coral reefs of the Mexican Pacific Coast.