Abstract Aim The aim of this study was to investigate the isotopic signature of P. brasiliana captured in three different points along the river flow toward the sea of the Prumirim River, northern coast of the state of São Paulo/Brazil in order to test the hypothesis of similarity between isotopic signature of individuals living in separated areas of the river. Methods We used stable isotope analyses (δ13C and δ15N) at three points of the river and ANOVA and Bayesian Ellipses analyses were performed. Results Our results showed that are a differential isotopic enrichment along the river course in 13C, providing important results on the environmental condition and anthropogenic impacts in the region. In addition, the food biology of P. brasiliana was characterized as a primary consumer corroborating with the detritivores feeding habit observed in previous studies of stomach content analysis. Conclusions Our research, limited to a single area along the northern coast of the state of São Paulo, uncovers intriguing findings that merit replication in other areas within the region. This is particularly crucial given the rising number of anthropogenic influences resulting from urban development, underscoring the need for improved monitoring of these areas.

Resumo Objetivo O objetivo deste estudo foi investigar a assinatura isotópica de P. brasiliana capturada em três diferentes pontos ao longo do fluxo fluvial em direção ao mar do rio Prumirim com a finalidade de testar a hipótese de similaridade entre a assinatura isotópica de indivíduos que vivem em areas diferentes do rio. Métodos Foram utilizadas análises de isótopos estáveis (δ13C e δ15N) em três pontos do rio e foram realizadas análises de Stable Isotope Mixing Models e Bayesian Ellipses. Resultados Nossos resultados mostraram que há um enriquecimento isotópico diferencial ao longo do curso do rio em 13C, fornecendo resultados importantes sobre as condições ambientais e os impactos antropogênicos na região. Além disso, a biologia alimentar de P. brasiliana foi caracterizada como um consumidor primário, corroborando com o hábito alimentar de detritívoros observado em estudos anteriores de análise de conteúdo estomacal. Conclusões Nossa pesquisa, limitada a uma única área ao longo da costa norte do estado de São Paulo, revela descobertas intrigantes que merecem ser replicadas em outras áreas dentro da região. Isso é especialmente crucial dada a crescente quantidade de influências antropogênicas resultantes do desenvolvimento urbano, ressaltando a necessidade de um monitoramento aprimorado dessas áreas.

ABSTRACT Ejaculate allocation patterns vary widely among species and often depend on characteristics of the individual. However, it is poorly known whether ejaculate allocation patterns change in response to distinct ontogenetic stages (i.e., adolescent vs. adult). The present study aims to describe the mating process and test variations in ejaculate allocation in response to the ontogenetic stage of the Chilean kelp crab Taliepus dentatus (H. Milne Edwards, 1834). Mating consists of the following sequence: (1) pre-copulatory guarding (i.e., male grasping female and/or caging female between legs), (2) copulation in sternum-to-sternum position, and (3) post-copulatory guarding (i.e., male grasping female or carrying her around by the chelae). The mating behavior and ejaculate allocation pattern differed between the two contrasting male ontogenetic stages. Adolescent males generally delivered less ejaculate in repeated short copulations and adult males transferred more ejaculate in a single extended copulation. Ejaculate allocation in adolescents was dependent on female size, but not so in adults. Variation in the ejaculate allocation pattern may be common in species with contrasting male ontogenetic stages, where less competitive males (i.e., adolescents) economize their limited seminal reserves. Conversely, adults which have a greater capacity to produce seminal material (fluids + spermatozoa) may invest greater quantities of seminal material.

Differences on reproductive performance between two sampling points of the porcelain crab Pachycheles monilifer from Ubatuba (São Paulo, Brazil), one from Itaguá Beach (living on Schizoporella errata) and the other from Grande Beach (living on Phragmatopoma caudata) has been previously observed. Therefore could be expected a specific behavior in substrate preference to optimize the best biogenic habitat. Considering this premise, our goal was to test the substrate preference of this species when both substrates were simultaneously available. In total, 185 individuals were collected in these same localities and they were submitted to substrate selection experiments. The trials were conducted on containers with quiet seawater at 28 ± 1°C and under dark photoperiod. Specimens were exposed to substrates by 30 min. Trials started with the release of one animal per treatment in the middle of the opposite side to the substrate inside the containers. After the established time, the substrate preference of each porcelain crab was verified. As result, no preference pattern was found and the choices in the experiment were not significantly different from the expected. This lack of preferences may be an indication that porcelain crabs are generalists in habitat use regardless of sex of individuals and potential benefit in fitness. Therefore, the differences on the reproductive aspects of the P. monilifer probably are associated with environment factors not simulated in this study and may indicate the occurrence of plasticity in habitat selection behavior.

The area between 37° and 41°S of the southeastern Pacific coast, have a great number of microtidal (tidal range less than 2 m) estuaries. One of the most important estuaries in these latitudes is the Valdivia River estuary, whose thermal and haline structure is poorly known. Thus, this work, through hydrographic measurements of temperature and salinity taken during an annual seasonal cycle and the analysis of the main forcings (tide, river flow, wind and solar radiation) explain the variability and its changes in vertical stratification. The analysis of the the thermohaline structure of the water column revealed that the estuary varied seasonally behaving like a salt-wedge estuary in winter and spring due to a higher flow of tributaries. However, in summer and autumn behaved as partially mixed due the lower river flow. In winter and spring the water column showed a temperature inversion which was associated with a large surface heat loss and subsurface advection of warm waters from the adjacent ocean to into the estuary that is not mixed with the surface due to intense stratification by salinity. The change in the estuarine salt-wedge regime to partially mixed according to the season and the presence of thermal inversion seasonal are necessary hydrographic features to implement conservation efforts of vulnerable habitat into the zone (nursery areas of juvenile species), and use of this system for aquaculture activities and marine resources management.

La costa sureste del Océano Pacífico entre 37° y 41°S, se caracteriza por la presencia de un gran número de estuarios micromareales (rango mareal menor a 2 m). Uno de los estuarios más importantes dentro de estas latitudes es el estuario del río Valdivia, cuya estructura y dinámica termal y halina es poco conocida. Mediante mediciones hidrográficas de temperatura y salinidad tomadas durante un ciclo estacional anual y el análisis de sus principales forzantes (marea, caudal del río, vientos y radiación solar) se explica la variabilidad así como sus cambios en la estratificación vertical. El análisis de la estructura termohalina de la columna de agua reveló que el estuario varió estacionalmente comportándose como un estuario de cuña salina en invierno y primavera producto del mayor caudal de los ríos afluentes, mientras que en verano y otoño se comportó como parcialmente mezclado, producto del menor caudal de los ríos. En invierno y primavera la columna de agua presentó inversión térmica, la cual fue asociada a pérdida de calor superficial y a la advección sub-superficial de aguas cálidas desde el océano adyacente hacia el interior del estuario que no se mezclaron con las de la superficie debido a la intensa estratificación salina. El cambio en el régimen estuarino de cuña salina a parcialmente mezclado según la estación del año y presencia de la inversión térmica estacional, son características hidrográficas necesarias tanto para la implementación de esfuerzos de conservación de hábitat vulnerables presentes en la zona (áreas de crianza de juveniles de especies explotadas), como para la utilización de este sistema para actividades de acuicultura y manejo de recursos marinos.

The settlement of decapod crustaceans in estuarine environments is the last stage in a complex process in which meroplanktonic species close the pelagic life phase. This process has successive stages, beginning with the formation of larval patches offshore, their transport to nursery areas, the exploration of suitable substrates for settlement, and the metamorphosis into juveniles. The interactions between physical factors and the behavior of competent larvae regulate the diverse stages of this process, finally determining the rates of local settlement. This study analyzes the relative importance of physical forcings that act on the meso-scale (i.e. wind stress, sea level, river runoff) and micro-scale (local temperature conditions, salinity, substrate type) on the settlement of megalopae of the brachyurans Cancer edwardsii and C. coronatus, the principal species of the commercial crab fishery in Chile. Passive larval collectors were installed on the sea bottom for 73 consecutive days during the period of maximum recruitment (i.e. abundance of juvenile I) at the mouth of the Valdivia River estuary; the substrate consisted of coarse sand and something similar to an algal mat. The results showed that: a) the settlement was characterized by extended periods of a few settlers alternating with peaks that did not necessarily coincide for the studied species, b) the settlement of C. edwardsii was related to multiple forcings generated by the advection of warm waters toward the coast, c) the settlement of C. coronatus was related to forcings generated by coastal upwelling, d) the larvae of both species did not differ in the magnitude of settlement on heterogeneous substrates. This study shows that larval settlement patterns are species-specific, even in sympatric and closely related species. Thus, any generalization by taxa should be well supported by comparative studies on the same spatiotemporal scale.

El asentamiento de crustáceos decápodos en ambientes estuarinos, es la última etapa de un complejo proceso en que las especies meroplanctónicas cierran la fase de vida pelágica. Este proceso tiene etapas sucesivas, que comienza con la formación de parches larvales frente a la costa, su transporte hacia las zonas de crianza, exploración de sustrato en busca de un lugar adecuado para el asentamiento y la metamorfosis a juvenil. Las interacciones entre los factores físicos y el comportamiento de las larvas competentes regulan las diversas etapas de este proceso, determinando finalmente las tasas de asentamiento locales. En este estudio se analiza la importancia relativa de las forzantes físicas que actúan a meso-escala (i.e. estrés del viento, nivel del mar y caudal del río) y micro-escala (condiciones locales de temperatura, salinidad y tipo de sustrato) sobre el asentamiento de megalopas de los braquiuros Cancer edwardsii y C. coronatus, principales jaibas comerciales en la pesca artesanal chilena. Para esto se instalaron colectores larvales pasivos de fondo por 73 días consecutivos en el periodo de máximo reclutamiento (i.e. abundancia de juvenil I), en la desembocadura del estuario del río Valdivia y se dispuso de arena gruesa y un símil de tapiz algal como sustrato. Los resultados mostraron que: a) el asentamiento está caracterizado por extensos periodos de escasos asentados alternados por pulsos de máximos, que no necesariamente coinciden entre las especies estudiadas, b) el asentamiento de C. edwardsii mostró estar relacionado con múltiples forzantes que generan la advección de aguas cálidas hacia la costa, c) el asentamiento de C. coronatus tuvo relación con las forzantes que generan la surgencia costera, d) las larvas de ambas especies no difieren en el asentamiento sobre sustratos heterogéneos. Este estudio mostró que los patrones de asentamiento larval son especie específicos, incluso en especies simpátricas y estrechamente emparentadas. Así, cualquier generalización por taxa debe ser bien soportada por estudios comparativos en la misma escala espacio-temporal.