Jesús Emilio Michel-Morfín

Although Spondylus limbatus is a fishery resource in several Latin American countries and has been widely reported throughout the Panamic Province, gaps remain in the knowledge of its distribution and ecology. This bivalve has been exploited since pre-Hispanic times, although the specific harvesting grounds are still uncertain. To contribute to malacological issues of both archaeological and contemporary interest, we established a reference collection that will serve as a basis for future studies, particularly geochemical analyses. Sampling consisted of recovering approximately four individuals per locality, obtained mainly from local food consumption, while recording information on their provenance and collection environment, amongst other data. In total, 180 individuals were recovered from shallow waters at 72 localities distributed across eight countries of the region. Collection sites included open coasts, gulf and bays that may comprise islands and shoals. This work documents new localities in areas where previous information was scarce or absent, such Jalisco in Mexico and El Salvador, Nicaragua and Panama, thereby significantly expanding current knowledge of the distribution of this species.

Ongoing global change and anthropogenic pressures are increasingly impacting coastal ecosystems, leading to habitat degradation and disrupted connectivity. Along the Tropical Eastern Pacific, multiple habitat discontinuities and oceanographic barriers, such as biogeographic transition zones, sedimentary coastal gaps, and major current systems, limit dispersal in rocky-shore taxa. Despite their cultural and economic importance, research on Tropical Eastern Pacific Spondylus remains geographically limited, underscoring a critical lack of knowledge on their population dynamics, dispersal, genetic diversity, and evolutionary history. Using high-resolution genome-wide SNPs, we revealed pronounced population structure in Eastern Pacific S. limbatus and S. crassisquama, with strong genetic differentiation of Central American populations from Mexican ones, and the Cortesian population from the others in S. limbatus, whereas S. crassisquama exhibited a similar but weaker pattern, primarily structured by the Southern California Bight. This study provides the first comparative genomic analysis of population structure in both species, with important implications for conservation, as genetically distinct management units must be recognized to ensure the sustainable management of these ecologically and economically important bivalves.

El archipiélago de Revillagigedo se ubica en el Pacífico este tropical y consta de 4 islas volcánicas, isla Clarión es la más occidental y remota de este parque marino de México. Esta región está influenciada por aguas frías provenientes de la corriente de California y aguas cálidas de la corriente Norecuatorial, lo que resulta en una zona de convergencia, con una alta biodiversidad marina. Clarión es una isla pequeña y distante, dominada por acantilados, con playas arenosas-rocosas en su cara sur, lo que se traduce en áreas poco accesibles para llevar a cabo investigaciones. El objetivo de esta contribución es dar a conocer una lista de especies de babosas marinas presentes en la isla. El estudio se llevó a cabo entre enero y marzo de 2023, y febrero-marzo de 2024, a través del muestreo continuo en playas, pozas intermareales y zonas arrecifales someras de la cara sur de la isla. En total, se registraron 14 especies de babosas marinas, 13 registros nuevos para esta isla y 5 para el archipiélago de Revillagigedo. Este estudio contribuye significativamente al conocimiento de la biodiversidad de las babosas marinas heterobranquias insulares del Pacífico tropical.

Humic substances and beneficial microorganisms are key biostimulants for sustainable agriculture and global food security in the face of climate change. Marine bacteria are emerging as a promising source of plant-beneficial microbes, tapping into a microbial diversity as immense as the oceans themselves. However, their potential, limitations, and mechanisms of action––especially in combination with other biostimulants––remain largely unexplored. In this study, we isolated the Streptomyces sp. LAP3 strain from the giant limpet Scutellastra mexicana. We evaluated the efficacy of the marine bacterium, applied alone or in combination with the humic product Leonardite hydrolate (L), in enhancing tomato performance under field conditions. Treatments included: (1) marine Streptomyces (MS), (2) Leonardite hydrolate (L), (3) both biostimulants (MS + L), and (4) a control (CTRL). We assessed growth, photosynthetic performance, antioxidant responses, and fruit yield and quality. Both biostimulants individually improved plant performance, but their combination had a significant synergistic effect, markedly boosting tomato productivity, thermotolerance, and resilience during a heatwave. Enhanced photosynthetic efficiency and antioxidant enzyme activity were associated with improved agronomic traits. These results highlight the potential of combining Streptomyces sp. LAP3 and Leonardite hydrolate as an eco-friendly strategy to increase crop productivity, strengthen stress resilience, promote sustainable agriculture, and reduce reliance on agrochemicals.

The biodiversity of mollusks, particularly cephalopods, has not been exhaustively determined in the Revillagigedos ecoregion, which is a biodiversity hotspot for several marine groups located in the Tropical East Pacific Province. In our study, we detected and examined ocellate octopuses from Socorro and Clarion Islands, and determined their identity using morphological criteria and molecular data from two mitochondrial genes (COIII and COI). The taxon identified was Octopus oculifer, a species considered endemic to the Galapagos Archipelago. In addition, according to our analyses, O. mimus, O. hubbsorum and O. oculifer are very closely related and may represent a species complex comprised of three morphotypes. We found that the evolutionary relationships among octopuses are not determined by the presence of ocelli. This study is the first to report a clade represented by ocellate and non-ocellate species, in addition, the identity of cephalopods in the Revillagigedos was determined with analytical support.

The present study originated with the expansion of the boardwalk within the urban and port area of Manzanillo, México. Prior to civil works related to the placement of tetrapods, surveys of potential sites for the relocation of benthic organisms in alternative areas were carried out. Based on indicators of the physical–chemical environment and biotic factors, nine areas with potential for relocation were evaluated. The areas of greatest potential were associated with environments located away from the influence of the port environment. A total of 13,559 benthic organisms belonging to 68 species associated with three main substratum types (rocky, sandy, and mixed) were collected. There were no differences in the ecological indices between the three substrata. The proximity of the collection area to the influence of port traffic and sources of pollution associated with the physical environment could be an important factor that affects ecological indices and the reduction in the abundance of some protected species and species of commercial interest. The success of collection and relocation processes depends on minimizing possible errors, especially during transportation, when overcrowding, handling, and damage resulting from variable physico‐chemical conditions should be avoided. Through a scheme of actions based on ecological principles, management actions, and civil engineering technology, it was possible to carry out mitigation, conservation, and habitat improvement actions in coastal marine environments exposed to anthropogenic impacts.

Scutellastra mexicana is the largest known patellid limpet species and probably is one of the most endangered marine invertebrates. The species was once distributed along the American Pacific coast from Mexico to Peru, but their large size (up to 35 cm long) and easy accessibility (shallow sublittoral), made it very vulnerable to human collection and now is extinct on most of the mainland Mexican coast. In August 2017, a large population of this species was found on María Cleofas island, off the coast of west‐central Mexico (Marías Archipelago, Pacific Ocean). This constitutes the only report of a population of this species since 1988. A total of 808 adult individuals of up to 26 cm in length and 20 cm in width were estimated, together with the presence of juveniles, suggesting that it is a self‐sustaining population. The population was monitored in August 2017 and August 2018. Although the species is under the category ‘Special Protection’ in the General Mexican Wild Law, and that María Cleofas island is a Biosphere Reserve, fishermen that operate with impunity in the area decimated the limpet population within a year of its discovery. Abundance in the shallowest area decreased significantly from 120 individuals per transect (65 m long and 2.75 m wide) in August 2017 to 48 individuals in August 2018, and the estimated adult population decreased from 808 to 304 limpets. Neither passive national conservation policies nor local practices have reduced current threats to biodiversity and resource depletion in Marías Archipelago. Protected areas like this are ‘paper parks’—parks in name only—because there is no active conservation strategy or protection of marine species.

Conus snails produce venoms containing numerous peptides such as the α-conotoxins (α-CTXs), which are well-known nicotinic acetylcholine receptor (nAChR) antagonists. Thirty-eight chromatographic fractions from Conus princeps venom extract were isolated by RP-HPLC. The biological activities of 37 fractions (0.07 µg/µL) were assayed by two-electrode voltage clamp on human α7 nAChRs expressed in Xenopus laevis oocytes. Fractions F7 and F16 notably inhibited the response elicited by acetylcholine by 52.7 ± 15.2% and 59.6 ± 2.5%, respectively. Fraction F7 was purified, and an active peptide (F7-3) was isolated. Using a combination of Edman degradation, mass spectrometry, and RNASeq, we determined the sequence of peptide F7-3: AVKKTCIRSTOGSNWGRCCLTKMCHTLCCARSDCTCVYRSGKGHGCSCTS, with one hydroxyproline (O) and a free C-terminus. The average mass of this peptide, 10,735.54 Da, indicates that it is a homodimer of identical subunits, with 10 disulfide bonds in total. This peptide is clearly similar to αD-CTXs from species of the Indo-Pacific. Therefore, we called it αD-PiXXA. This toxin slowly and reversibly inhibited the ACh-induced response of the hα7 nAChR subtype, with an IC₅₀ of 6.2 μM, and it does not affect the hα3β2 subtype at 6.5 μM.