Taxonomic identity of Distapliastylifera (Tunicata, Ascidiacea), a new arrival to the eastern Pacific displaying invasive behavior in the Gulf of California, Mexico.

A colonial ascidian of the genus Distaplia caused a mass mortality of the pen shell Atrinamaura (Sowerby, 1835) during June 2016 in the southwest of the Gulf of California (Mexico), with a significant socio-economic cost. Tentatively identified in previous works as Distapliacf.stylifera, a precise taxonomic determination was still lacking. In the present work, based on a detailed morphological study, it is confirmed that this aggressive species is Distapliastylifera (Kowalevsky, 1874). Originally described from the Red Sea, the species currently has a wide circumtropical distribution (with the exception of the Eastern Pacific to date) and is reported as introduced in parts of its range. The present account thus represents an important range extension of this species. However, when revising the original description and later observations, the reported variability of several characters makes it likely that the binomen is in fact a complex of species, as is common in other ascidians with wide distributions. A complete morphological and genetic study including populations from the entire range of distribution would be necessary to settle the status of D.stylifera. Taxonomic uncertainties hinder a correct interpretation of biogeographical patterns and inference on the origin of the studied population. Nevertheless, the known introduction potential of the species, coupled with an explosive growth in an anthropized environment, and the lack of any previous reports in the Eastern Pacific, strongly suggest that the investigated population represents yet another instance of ascidian introduction. From the point of view of management, its invasive behavior is cause for great concern and warrants mitigation measures.

Reduced fish diversity despite increased fish biomass in a Gulf of California Marine Protected Area.

Multi-use marine protected areas (MUMPAs) are a commonly applied tool for marine conservation in developing countries, particularly where large no-take reserves are not socially or politically feasible. Although MUMPAs have produced benefits around the world, the persistence of moderate fishing pressure reduces the likelihood of achieving the primary objective of these areas, which is the conservation of ecosystems. In this study we used traditional and functional metrics to evaluate how fish assemblages changed through time in a MUMPA, including shifts in species responses and in ecological processes. We conducted visual censuses of fishes at Espíritu Santo Island, México (MUMPA; N = 320; 24°N, 110°W) from 2005 to 2017 to assess fish richness, size-distribution and density. Three functional indices were calculated using six traits (size, mobility, period of activity, aggregation, position in water column and diet): functional richness (volume occupied by species), dispersion (complementarity between species) and originality (inverse of functional redundancy). We compared fish diversity among three management zone types (sustainable fishing, traditional fishing and no-take zones), through a 13-year period, assessing which species increased or decreased in occurrence, density, and biomass, and how indices respond over time. Despite a general increase in biomass and stability in density and originality, we detected a reduction in fish biodiversity in the form of declines in species and functional richness, which could imply the risk of local extinction and decrease in certain ecosystem processes. In addition, changes in functional dispersion showed that some functions are losing representation through time. Although no single cause is apparent, such factors as competitive interactions, habitat loss and persistence of fishing pressure potentially explain these decreases. The rise in biomass was associated with a general increase in the average size, rather than increased biomass of commercial species, as the latter remained stable during the study period. Expansion of no-take areas, enforcement of fishing regulations, and surveillance in core zones, should be implemented to reverse the decline in particular species and to promote conservation of fish functional diversity in this MUMPA.

Ecological patterns in anchialine caves.

Anchialine caves are characterized by high levels of endemism and extreme conditions. However, few ecological studies have been conducted in these ecosystems. This study integrates biotic and abiotic parameters of two sets of cave systems with contrasting high and low species richness. Seven ecological patterns are used to explain the expected species richness and density in an anchialine cave. In addition, the population size for conspicuous macrofauna was estimated. The high impact that single-events have on anchialine fauna are also reported. These findings reinforce the conclusions of previous studies of the high extinction risk of anchialine cave fauna, and substantiate the necessity of ad hoc conservation strategies for anchialine caves.

Efficacy of calcein and Coomassie Blue dyeing of shell growing-edges and micro growth-bands: ageing juvenile of Pinctada mazatlanica (Pterioida: Pteriidae).

Age validation is the first step to determine shellfish species age determination. This information is vital for different inferential models used in marine ecosystem management activities. In spite that various validation techniques are used for marking carbon calcium structures, the calcein marking technique for oysters had never been used for age validation in Pinctada mazatlanica. Thus the objectives of this study included: the evaluation of calcein to mark a shell growing-edge, and the efficacy of Coomassie Blue staining on posterior shell growth, to produce visible micro growth-bands that would enable age validation of juvenile mother-of-pearl oysters. Oysters were collected and cultivated at The Perlas del Cortez S. de R. L. MI. pearl-farming operation, in Pichilingue, La Paz Bay, Baja California Sur, Mexico; a total of 36 oysters (shell height 11.5-36.4 mm) were injected with calcein (0.125 g/L), and another 50 oysters (shell height 14.8-42.7 mm) were submersed in calcein (0.4 and 0.7 g/L). Shell slices of calcein-marked oysters were posteriourly stained with Coomassie Blue R-25 for micro growth-band recognition. Our results showed that Calcein marking only worked by submersion and produced a concise bright lime-green florescent band along the growing-edge with clear boundaries for both concentrations. However, marks resulted better at the lower calcein concentration (0.4 g/L) with more "perfect" and "good" marks on the growing-edge (p = 0.0012). Commassie Blue staining technique was successful, and allowed to conclude that one micro growth-band was laid down per day, similar to other oyster species. Mean 15-d increment of shell growth height was slightly greater at the lower calcein concentration (= 0.735 mm) than at the higher one (= 0.577 mm) (not significant difference, p = 0.198). Calcein marking of shell growing-edges and Commassie Blue staining of posterior shell growth, as a method for age validation is recommended for shellfish shell growth-band counts. This will allow back-dating for estimation of very precise colonization dates, both spatially and temporally in future work.

Efficacy of calcein and Coomassie Blue dyeing of shell growing-edges and micro growth-bands: Ageing juvenile of Pinctada mazatlanica (Pterioida: Pteriidae) / Eficiencia de la tinción de bandas de crecimiento con calceina y azul de coomassie, para estimar la edad de jóvenes de Pinctada mazatlanica (Pterioida: Pteriidae)

Age validation is the first step to determine shellfish species age determination. This information is vital for different inferential models used in marine ecosystem management activities. In spite that various validation techniques are used for marking carbon calcium structures, the calcein marking technique for oysters had never been used for age validation in Pinctada mazatlanica. Thus the objectives of this study included: the evaluation of calcein to mark a shell growing-edge, and the efficacy of Coomassie Blue staining on posterior shell growth, to produce visible micro growth-bands that would enable age validation of juvenile mother-of- pearl oysters. Oysters were collected and cultivated at The Perlas del Cortez S. de R. L. MI. pearl-farming opera tion, in Pichilingue, La Paz Bay, Baja California Sur, Mexico; a total of 36 oysters (shell height 11.5-36.4mm) were injected with calcein (0.125g/L), and another 50 oysters (shell height 14.8-42.7mm) were submersed in calcein (0.4 and 0.7g/L). Shell slices of calcein-marked oysters were posteriourly stained with Coomassie Blue R-25 for micro growth-band recognition. Our results showed that Calcein marking only worked by submersion and produced a concise bright lime-green florescent band along the growing-edge with clear boundaries for both concentrations. However, marks resulted better at the lower calcein concentration (0.4g/L) with more “perfect” and “good” marks on the growing-edge (p=0.0012). Commassie Blue staining technique was successful, and allowed to conclude that one micro growth-band was laid down per day, similar to other oyster species. Mean 15-d increment of shell growth height was slightly greater at the lower calcein concentration ( =0.735mm) than at the higher one ( =0.577mm) (not significant difference, p=0.198). Calcein marking of shell growing- edges and Commassie Blue staining of posterior shell growth, as a method for age validation is recommended for shellfish shell growth-band counts. This will allow back-dating for estimation of very precise colonization dates, both spatially and temporally in future work.

La validación de la edad es el primer paso para determinar las edades de las especies de moluscos, esta información es de vital importancia para los diferentes modelos de inferencia utilizados en actividades de gestión de los ecosistemas marinos. Diversas técnicas de valida- ción se utilizan para marcar estructuras de carbonato de calcio, aunque la técnica de marcado de calceína en ostras nunca se había utilizado para la validación de la edad de P. mazatlanica. Los objetivos de este estudio fueron: evaluar la calceína como marcador interno de la concha y la eficiencia del azul de Coomassie en la tinción de la matriz proteica de la concha, para facilitar la observación y conteo de micro bandas de crecimiento que permiten validar la edad de las ostras juveniles de madre perla. Las ostras fue- ron recolectadas en la costa de la empresa Perlas del Cortez S. de RL MI., en Pichilingue en Bahía de La Paz, Baja California Sur, México. Se inyectaron 36 ostras (altura de concha 11.5-36.4mm) (0.125g/L de calceína) y otras 50 ostras (altura de la concha 14.8-42.7mm) se sumergieron (0.4 y 0.7g/L de calceína). Secciones de la concha marcadas con calceína fueron teñidos con azul de Coomassie R-25 para el reconocimiento de las micro bandas de crecimiento. El marcado con calceína fue exitoso por inmersión y produjo una banda fluorescente de color verde lima brillante con- cisa a lo largo del crecimiento interno de la concha. Sin embargo, las marcas fueron mejores a una concentración de calceína inferior (0.4g/L), con mayor cantidad de marcas “buenas” y “perfectas” (p=0.0012). La técnica de tinción con azul de Commassie también fue exitosa. Se detectó un crecimiento diario por micro banda, similar a lo encontrado en otras especies de ostras. La diferencia del crecimiento medio en relación a la altura de la concha en un lapso de 15 días, fue ligeramente mayor con una concentración de calceína inferior ( =0.735mm) que con la de mayor concentración ( =0.577mm), pero no significativamente (p=0.198). El marcado de conchas con calceína y tinción de matrices proteicas con azul de Coomassie posterior a su crecimiento, es recomendando como un método para la validación de la edad facilitando el conteo de micro bandas de crecimiento internas de la concha. Además, permitirá estimar edades con el fin de predecir fechas de colonización y ubicación de bancos naturales.