Molecular assessment of the species of Gracilariaceae (Gracilariales, Rhodophyta) from the Yucatan Peninsula, Mexico, including two new records for the Mexican Atlantic

Background. The Gracilariaceae is one of the most diverse and abundant families of marine red algae. Most species in this family exhibit high morphological variability and overlapping of characters. In the Yucatan Peninsula 30 species have been historically recorded, but the phylogenetic identity for many of them is still unknown. Questions: Is the current diversity of the family in the area overestimated? Studied species: Crassiphycus caudatus, C. corneus, C. usneoides, Gracilaria flabelliformis, G. hayi, G. cf isabellana, G. microcarpa, G. occidentalis, G. suzanneae, Gracilariopsis tenuifrons. Study site and dates: Campeche: km 33 carretera Champotón, Bahía Tortuga, Puente Xen Kan III, Punta Xen, Sabancuy, 2017, 2018; Yucatan: Puerto Sisal, Puerto Progreso, Puerto Chicxulub, Puerto Telchac, 2018; Quintana Roo: Playa 88, Xcalacoco, Punta Esmeralda, 2019. Methods. Phylogenetic analysis (with COI-5P and rbcL sequences), supported by DNA species delimitation methods, genetic distances and morphological comparisons, allowed us to molecularly identify the specimens collected. Results. The phylogenetic identity of 10 species of Gracilariaceae was confirmed, two of which are new records for the Mexican Atlantic: G. hayi and G. suzanneae. Conclusion. The study demonstrated that the molecular assessment has proved to be very useful for the diversity evaluation, thus, the future phylogenetic identifies for the rest of morphospecies recorded in the area will allow a better approximation of Gracilariaceae diversity species.

Twice lost, twice found: A new species of Gonolobus (Apocynaceae: Asclepiadoideae) with a reappraisal of the genus in the Yucatan Peninsula Biotic Province

Gonolobus is reassessed in the Yucatan Peninsula Biotic Province (YPBP). The genus consists of seven taxa in the area: six species and two subspecies. These include a taxon that we propose here as a new species and the treatment of G. yucatanensis as a subspecies of G. stenanthus and the new combination G. stenanthus subsp. yucatanensis is proposed. These two taxa are endemic to the YPBP. The other species are G. barbatus (for which we propose a lectotype), G. cteniophorus, G. fraternus, G. glaberrimus, and G. leianthus. The new species is G. caamalii Carnevali & R. Duno, restricted to the Yucatán state in Mexico and distinguished by its corolla lobes with a dark purple (almost black) longitudinal, callose band along the proximal 2/3 on the right side of the lobes and a 1.1–1.3 mm broad, annular, continuous dark purple-black band surrounding the gynostemium and corona at the base of the corolla lobes. It appears related to G. leianthus from southern Megamexico, a species from humid forests at higher elevations and that differs in its larger flowers with broader corolla lobes and a strikingly different color pattern in the flowers. The new species is described, illustrated, and discussed. Entries for all Gonolobus species from the YPBP include a brief discussion and specimen citations. The conservation status of the Gonolobus taxa endemic to the YPBP are assessed either as as Endangered (EN) or as Near threatened (NT). Distributional maps for all Gonolobus from the area covered are presented. Finally, we offer a key to Gonolobus of the YPBP.

Late Holocene environmental change in Celestun Lagoon, Yucatan, Mexico

Epikarst estuary response to hydroclimate change remains poorly understood, despite the well-studied link between climate and karst groundwater aquifers. The influence of sea-level rise and coastal geomorphic change on these estuaries obscures climate signals, thus requiring careful development of paleoenvironmental histories to interpret the paleoclimate archives. We used foraminifera assemblages, carbon stable isotope ratios (δ13C) and carbon:nitrogen (C:N) mass ratios of organic matter in sediment cores to infer environmental changes over the past 5300 years in Celestun Lagoon, Yucatan, Mexico. Specimens (> 125 µm) from modern core top sediments revealed three assemblages: (1) a brackish mangrove assemblage of agglutinated Miliammina and Ammotium taxa and hyaline Haynesina (2) an inner-shelf marine assemblage of Bolivina, Hanzawaia, and Rosalina, and (3) a brackish assemblage dominated by Ammonia and Elphidium. Assemblages changed along the lagoon channel in response to changes in salinity and vegetation, i.e. seagrass and mangrove. In addition to these three foraminifera assemblages, lagoon sediments deposited since 5300 cal yr BP are comprised of two more assemblages, defined by Archaias and Laevipeneroplis, which indicate marine Thalassia seagrasses, and Trichohyalus, which indicates restricted inland mangrove ponds. Our data suggest that Celestun Lagoon displayed four phases of development: (1) an inland mangrove pond (5300 BP) (2) a shallow unprotected coastline with marine seagrass and barrier island initiation (4900 BP) (3) a protected brackish lagoon (3000 BP), and (4) a protected lagoon surrounded by mangroves (1700 BP). Stratigraphic (temporal) changes in core assemblages resemble spatial differences in communities across the modern lagoon, from the southern marine sector to the northern brackish region. Similar temporal patterns have been reported from other Yucatan Peninsula lagoons and from cenotes (Nichupte, Aktun Ha), suggesting a regional coastal response to sea level rise and climate change, including geomorphic controls (longshore drift) on lagoon salinity, as observed today. Holocene barrier island development progressively protected the northwest Yucatan Peninsula coastline, reducing mixing between seawater and rain-fed submarine groundwater discharge. Superimposed on this geomorphic signal, assemblage changes that are observed reflect the most severe regional wet and dry climate episodes, which coincide with paleoclimate records from lowland lake archives (Chichancanab, Salpeten). Our results emphasize the need to consider coastal geomorphic evolution when using epikarst estuary and lagoon sediment archives for paleoclimate reconstruction and provide evidence of hydroclimate changes on the Yucatan Peninsula.

Development of a stochastic bioeconomic model for the red octopus fishery on the Yucatan Peninsula: Implications for management

Although much effort has been dedicated to the management of the red octopus fishery on the Yucatan Peninsula (Mexico), managers have yet to incorporate economic aspects to ensure sustainable and profitable exploitation of this fishery resource. We developed a bioeconomic model that incorporated the uncertainty for the r and K parameters. We fit 3 models (Schaefer, Fox, and Pella–Tomlinson) to abundance index survey data and used the Akaike information criterion for model selection. The best fit corresponded to the Schaefer model. We built deterministic and stochastic versions of the Gordon–Schaefer model. Economic data (costs and prices) were determined from inter[1]views with fishermen. To estimate the posterior distributions of parameters and indicators, we used Bayesian methods with Markov chain Monte Carlo (MCMC) simulations. The deterministic results suggested that the maximum sustainable income was Mex$851.70 million, with a fishing effort of 3,650 fishing boats, while the maximum sustainable profit was $390.8 million, with a fishing effort of 2,472 fishing boats. The equilibrium point corresponded to an effort of 4,945 fishing boats. Regarding the stochastic model, the MCMC simulation results suggest that the maximum sustainable income distribution was not normal; its average was $856.1 million (SE 1.8) and the most likely value was $849.50 million. The most likely fishing effort at equilibrium was 4,970 fishing boats. Our results suggest the fishery could be operating close to the economic equilibrium point; if this is the case, fishing effort must decrease in order for annual profit to increase. Our approach will help make periodical re-evaluations of the fishery and establish management strategies to ensure the profitable and sustainable exploitation of the red octopus on the Yucatan Peninsula.

On the Understanding of the Hydrodynamics and the Causes of Saltwater Intrusion on Lagoon Tidal Springs

Springs are common features on the Yucatán coast. They can discharge either under the sea (submarine) or inland in coastal lagoons and wetlands. Previous observations of a coastal lagoon located on the northern Yucatán Peninsula (La Carbonera) reported sea water intrusion on a spring that discharge on a coastal lagoon (lagoon tidal spring). The saltwater intrusion occurs when the tide is at its lower level, which is the opposite to what has been reported for submarine springs in the Yucatán Peninsula. In this study, the hydrodynamics of the spring is analyzed and the driving forces controlling the seawater intrusion are identified and discussed. Time series of water levels, salinity, and velocity measurements in the lagoon, the aquifer, and the spring are analyzed by means of tide component decomposition and cross-correlations analysis of the tide signals. Results show that the main driving forces causing the intrusion are the density differences and pressure head gradients, and the mechanisms influencing the driving forces driving those differences are the tides, the friction in the lagoon, and the confinement of the aquifer; other mechanisms are discussed to present a complete idea of the complexity of the interactions between the coastal aquifer, the coastal lagoons, and the sea.

Native palms as an economically important non-timber forest product among rural communities in the Yucatán peninsula, Mexico

Objective. To analyze the valuation, use, and preservation of native palms as a non-timber forest product (NTFP) of high economic importance for rural communities in the Yucatán Peninsula, Mexico. Design/methodology/approach: The available literature on palms and their use in the Yucatán Peninsula (YP) was examined using the snowball method. Subsequently, different online flora databases were consulted in order to examine the taxonomic identities of palm species present in the YP. The reported uses were classified. Results: The YP has 20 native species that belong to 13 genera and three subfamilies. All of them are economically exploited as NTFPs, especially in construction (85%) and honey production (70%), followed by food and medicinal use (35% each), craftwork (30%), ornamental use (25%), and fodder (10%). These data confirm that native palms are an important livelihood means for the inhabitants of Mayan communities in the region. Study limitations/implications: The research faced a limited database of encyclopedias, anthologies, directories, books, or articles that interpret works or research about this topic. Findings/Conclusions: The local and regional use of palms represents an additional income for the people who use this natural resource on different productive scales, both in rural communities and city centers. An alternative to ensure the sustainability of palms would be to establish governmental programs for their reproduction