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- Variability in Carcinus maenas Fecundity Along lagoons and estuaries of the Portuguese coastPublication . N. Monteiro, J.; Ovelheiro, Andreia; Ventaneira, Ana M.; Vieira, Vasco; Teodosio, Maria; Leitão, FranciscoAlthough Carcinus maenas as a species is widely studied, research focusing on fecundity is still scarce. The main objective of this study was to evaluate size-fecundity relationships across diferent lagoons and estuaries, along the Portuguese coast, to understand how the local environment afects reproductive patterns. Between 2019 and 2020, ovigerous females were collected from the Southern (Ria Formosa and Ria de Alvor), Central (Rio Sado) and Northern regions (Ria de Aveiro) of Portugal, and the fecundity of each female was estimated by counting and weighing eggs. Morphometric relationships (carapace width–egg counting; egg counting–egg weight; body wet weight–egg weight; carapace width–body wet weight) were inferred from 180 egg-bearing females with a carapace width between 26.96 and 61.25 mm. A positive correlation between fecundity and the morphological parameters was observed. Diferences in fecundity were found among all systems, from northern to southern Portugal, varying between 22121 and 408538 eggs per female. Furthermore, a regional gradient was observed across regions, with lower temperature estuaries (Ria de Aveiro) displaying an increase in fecundity. The fecundity in Rio Sado was also afected by salinity. Fecundity diferences across regions were associated with hydrodynamics, temperature, and salinity diferences among systems. No statistically signifcant diferences were observed between Carapace Width—Body Wet Weight regressions performed in each studied system, indicating that, contrary to fecundity, the somatic growth of C. maenas is not afected by latitudinal or environmental conditions.
- Reproductive traits of the African mud crab (Panopeus africanus) on the South Portuguese coastPublication . N. Monteiro, J.; Ovelheiro, Andreia; Pinto, Miguel; Teodosio, Maria; Leitão, FranciscoSpecies with high economic relevance are widely studied in contrast with low economic relevance species such as Panopeus africanus, a small crab with a wide distribution along the eastern Atlantic coast, which remains poorly studied in regarding to the biological and ecological issues. Knowledge of reproductive patterns is essential to understand populations dynamics and species biological life-cycle traits. The main objective of the present research was to study the reproductive patterns of P. africanus. The population size structure, maturation stages and gametogenic development aspect, size at maturation, reproductive periods and morphometric-fecundity relationships of P. africanus in the southern Portuguese coast (Ria Formosa) was analysed. Crabs were sampled monthly, from January 2019 to December 2021, with traps and hand collected. The crab's carapace width (CW) ranged between 7 to 52 mm, and it was observed that in smaller and larger CW size classes, the proportion of males was higher, however in intermediate CW size classes the sex ratio was near 1:1. The gonads development was characterized based on histological analysis. Males presented four maturity developmental stages where two stages were immature and two were mature. Females presented six maturity developmental stages, where two stages were immature, and four stages were mature. Regardless of sex, the mean maturity size was 20 mm CW. A high percentage of mature individuals was observed throughout the year however, in the colder months the percentage of mature individuals was lower. Additionally, ovigerous females were only observed in the warmer months, pointing to a short breeding period occurring in the warmer months. Fecundity ranged between 12368 and 84140 eggs/female, following a positive correlation between CW/egg number. These novel results allowed to shed light on reproductive patterns of P. africanus population inhabiting the southern Portuguese coast, contributing also to a better understanding of the basic reproductive biology of this crab populations.
- Climate change vulnerability assessment of the main marine commercial fish and invertebrates of PortugalPublication . Bueno-Pardo, Juan; Nobre, Daniela; Monteiro, J. N.; Sousa, Pedro M.; Costa, Eudriano; Baptista, Vânia; Ovelheiro, Andreia; Vieira, Vasco; Chicharo, Luis; Gaspar, Miguel; Erzini, Karim; Kay, Susana; Queiroga, Henrique; Teodosio, Maria; Leitão, FranciscoThis is the first attempt to apply an expert-based ecological vulnerability assessment of the effects of climate change on the main marine resources of Portugal. The vulnerability, exposure, sensitivity, adaptive capacity, and expected directional effects of 74 species of fish and invertebrates of commercial interest is estimated based on criteria related to their life-history and level of conservation or exploitation. This analysis is performed separately for three regions of Portugal and two scenarios of climate change (RCP 4.5 and RCP 8.5). To do that, the fourth assessment report IPCC framework for vulnerability assessments was coupled to the outputs of a physical-biogeochemical model allowing to weight the exposure of the species by the expected variability of the environmental variables in the future. The highest vulnerabilities were found for some migratory and elasmobranch species, although overall vulnerability scores were low probably due to the high adaptive capacity of species from temperate ecosystems. Among regions, the highest average vulnerability was estimated for the species in the Central region while higher vulnerabilities were identified under climate change scenario RCP 8.5 in the three regions, due to higher expected climatic variability. This work establishes the basis for the assessment of the vulnerability of the human activities relying on marine resources in the context of climate change.
- A bayesian approach to infer the sustainable use of artificial reefs in fisheries and recreationPublication . Ramos, Jorge; Drakeford, Benjamin; Madiedo, Ana; Costa, Joana; Miguel de Sousa Leitão, FranciscoThe presence of artificial reefs (ARs) in the south of Portugal that were deployed a few decades ago and the corroboration of fishing patterns and other activities related to the use of these habitats have not been followed. It is important to note that monitoring the use of ARs was difficult in the past but is currently facilitated by the application of non-intrusive tools. In the present study, an approach is developed where, based on monitoring data from fishing and non-fishing boats, influence diagrams (IDs) are constructed to provide some evidence on fisheries or other use patterns and consequent AR effectiveness as coastal tools. These IDs allow us to infer various usefulness scenarios, namely catches, which are tangible, and satisfaction, which is intangible, and overall assessment of ARs and nearby areas in terms of human activities. After calibrating the Bayesian ID based on monitoring evidence, the obtained model was evaluated for several scenarios. In the base case, which assumes the occurrence of more fishing than recreation (assuming 3:1, respectively), the obtained utility is 18.64% (catches) and 31.96% (satisfaction). Of the scenarios run, the one that obtained the best results in the utility nodes together was the second one. The use of these tailored tools and approaches seems to be of fundamental importance for the adequate management of coastal infrastructures, particularly with regard to the inference of fishing resources and their sustainable use. An adequate interpretation based on the use of these tools implies being able to safeguard the ecological balance and economic sustainability of the communities operating in these areas.
- Macro and microscopic maturation stage key of green crab (Carcinus maenas, Linnaeus 1758): reproductive cycle and differences among estuarine systemsPublication . Ovelheiro, Andreia; N. Monteiro, J.; Gonçalves, Patrícia; Campinho, Marco António; Maia, Francisco; Teodosio, Maria; Leitão, FranciscoGonadal histology is a helpful tool to validate species' macroscopic maturity stages in fisheries biology. Regardless of the many studies on Carcinus maenas, there are still few concerning gonads tissue histology and description of maturity stages. In Portugal, information regarding this species' biology to help support the regulation of crab fisheries, including the minimum landing size, has not yet been defined. In this work, the macro and microscopic characteristics of the reproductive cycle of C. maenas, oogenesis, and spermatogenesis development stages along the Portuguese coast are described, and a new macroscopic scale based on the histological analyses is suggested. During 2019 and 2020, adult C. maenas (both males and females) were collected from the Ria de Aveiro estuary, Rio Sado estuary, and Ria Formosa lagoon, respectively, North, Center, and South Portugal. No-significant differences (P > 0.05) were observed in carapace width and individual weight between all systems. Significant differences (P < 0.05) were observed in gonad weight, gonadosomatic index, and Fulton's condition index between the Rio Sado estuary and Ria Formosa lagoon. Furthermore, significant differences (P < 0.05) in the oocyte diameter between the northern and southernmost locations suggest a geographic variation related to the local environmental conditions of each system. Principal component analysis (PCA) revealed maturity stage and carapace width an association, and a similar morphometry between Ria de Aveiro and Ria Formosa. Temperature was correlated to both maturity stage and carapace width in Ria de Aveiro and Ria Formosa. From the histological analysis and based on microscopic criteria, it was observed that females previously classified within the late macroscopic development stage 2 should be considered mature, so a classification change in the current ovary's developmental stage is proposed. These findings can allow fisheries researchers to reclassify the estimations of maturity ogives and help support the regulation of this species' fishery. The proposed macroscopic scale was validated by histological analyses and can be used elsewhere.
- Biological aspects of fish species from subsistence fisheries in “Bons Sinais” estuary, MozambiquePublication . Costa, E.F.S.; Mocuba, Jeremias; Oliveira, Daniel; Teodosio, Maria; Leitão, FranciscoKnowledge on biological aspects of commercially exploited fish is an important tool for assessing and managing of data-poor fisheries. In this study, we have collected information on biological aspects of commercial fish species, namely in the Bons Sinais estuary (BSE), Mozambique. Fish species were caught using a beach seine and a traditional fishing gear known as Chicocota, both used by local fishing communities for subsistence fisheries. The results revealed that most specimens caught were juveniles and below the size at first maturity. In general, mean body height (BH) estimated across all species (2.24 cm) was below the minimum mesh size established by Mozambique Fisheries Law (3.8 cm). Estimated W–L regression analysis were statistically significant with the coefficient of determination (r 2 ) explaining from 91 to 98% of the variance. The allometric coefficient b ranged from 2.728 (Stolephorus indicus) to 3.357 (Johnius dussumieri). All the species exhibited positive or isometric allometric growth, except S. indicus, which exhibited negative growth. This study provides new information that can be used to enhance sustainable fishery management in data-poor fisheries.
- First record of the nudibranch tenellia adspersa (Nordmann, 1845) in Portugal, associated with the invasive hydrozoan cordylophora caspia (Pallas, 1771)Publication . Encarnação, João; Seyer, Thomas; Teodosio, Maria; Leitão, FranciscoThe estuarine nudibranch Tenellia adspersa (Nordmann, 1845) was recorded for the first time in Portugal, while sampling for fouling fauna of artificial structures along the salinity gradient of the Guadiana estuary (SW Iberian Peninsula). Two specimens were found in association with the invasive hydrozoan Cordylophora caspia (Pallas, 1771) and kept in the laboratory for taxonomy purposes. After two days, batches of eggs were seen in C. caspia branches, while the nudibranchs were also actively feeding on the hydrozoan polyps. The fast generation times of T. adspersa, along with its food preference for C. caspia, might suggest a positive role of the nudibranch on controlling this invasive hydrozoan in the Guadiana estuary. Introduction routes and facilitation interactions are discussed.
- Does consistent individual variability in pelagic fish larval behaviour affect recruitment in nursery habitats?Publication . Baptista, Vânia; Costa, Eudriano; Carere, Claudio; Morais, Pedro; Cruz, Joana; Cerveira, Inês; Castanho, Sara; Ribeiro, Laura; Pousao-Ferreira, Pedro; Leitão, Francisco; Teodosio, MariaIndividual animals across all taxa differ consistently in behaviour, i.e. they show personality traits. This inter-individual variability has significant ecological and evolutionary consequences, since it affects a range of population-level processes. Here, we focus on the selection and recruitment of nursery habitats in temperate fish larvae. The "Sense Acuity and Behavioural Hypothesis" has proposed that fish larvae could detect and follow environmental cues to actively choose suitable nursery habitats. We empirically tested this hypothesis questioning if this non-random active process occurs and if it could be linked to consistency in individual behaviours. Individual larvae of the white seabream Diplodus sargus (Linnaeus, 1758) were tested repeatedly at different ages in a two-channel choice-chamber apparatus exposing them to a flow with different stimuli, as nursery habitats (lagoon, coastal), different temperatures or salinities and recording exploratory activity and preference in the different conditions. Most larvae changed behaviour during ontogeny, but they were also significantly consistent in their behaviour, revealing strong individuality; yet, no significant preference for the presented stimuli emerged, nor it was related to individuality. Exploratory activity was higher when larvae showed unresponsive or inconclusive behaviours, meaning that the larvae tried to find a different stimulus from the one that we were offering or had random habitat selection. Individual behavioural consistency could influence the process of searching for suitable nursery habitats and, consequently, dispersion and connectivity of white seabream population. Characterizing the behaviour of temperate pelagic marine fish larvae may shed light on fish recruitment variability, help refining larval dispersion models and possibly help understanding effects of climate change on population distribution and connectivity. Significance statement A Chinese idiom says that "It is easier to change mountains and rivers than to alter one's character." What about fish? Well, fish can exhibit individuality traits that control autoecological and demecological processes. For example, shy fish have lower fitness while the rate of invasion progress is faster in populations with bolder individuals. Individuality studies rarely focused on fish larvae, except for coral fish. So, we tested if temperate fish larvae display consistent behaviour throughout ontogeny. This goal delves into the Sense Acuity And Behavioural Hypothesis which incorporated behaviour into the hypotheses deeming to explain fish recruitment variability. We found that temperate fish larvae display consistent individual behavioural differences in exploratory activity since early in ontogeny. This confirms the deterministic role of pelagic fish larvae behaviour on population connectivity processes, namely to control their dispersion and choose a nursery habitat.
- Modelling the ingress of a temperate fish larva into a nursery coastal lagoonPublication . Baptista, Vânia; Leitão, Francisco; Morais, Pedro; Teodosio, Maria; Wolanski, EricThe development of sensorial acuity and swimming capabilities of coastal fish larvae and their responses to coastal nursery cues are essential for recruitment success. Most studies of the response of fish larvae to environmental cues and their recruitment into nursery areas have focused on coral reef fish and only a few studies focused on fish species from temperate regions. The Sense Acuity and Behavioural (SAAB) Hypothesis proposes that fish larvae in temperate regions can sense nursery cues and ingress into estuarine ecosystems by using several active swimming strategies. We tested the SAAB hypothesis by studying the ingress of a temperate fish larvae - white seabream Diplodus sargus (Linnaeus, 1758) - into a coastal nursery area, the Ria Formosa Lagoon, Portugal. We combined the results from studies of sensory acuity, swimming capabilities and personality traits of post-flexion larvae with a fine-scale biophysical model to quantify the ingress of the white seabream into the lagoon. Data showed that the location of spawning sites and the directional swimming capabilities are both important for the successful ingress of white seabream larvae into the lagoon. Recruitment was higher when spawning grounds were located in areas with depths between 15.1 and 16.9 m and when post-flexion larvae used their directional swimming capabilities. The larvae ingressed passively into the lagoon with the tidal currents at pre-flexion stage and actively by using their directional swimming capabilities at post-flexion stage. Directional swimming also prevented larval export into the coastal area. When spawning occurred away from the seagrass smell plume emanating from the lagoon, the fish larvae were advected away and lost at sea. This work demonstrated the relevance of combining fish larvae behaviour and oceanography processes in modelling the dispersion of fish larvae to estimate recruitment.
- Implications of warming on the morphometric and reproductive traits of the Green Crab, Carcinus maenasPublication . N. Monteiro, J.; Bueno-Pardo, Juan; Pinto, Miguel; Pardal, Miguel A.; Martinho, Filipe; Miguel de Sousa Leitão, FranciscoUnderstanding the relationship between environmental temperature and the biological traits of organisms is fundamental to inferring the potential impacts of climate change. In the case of marine poikilotherm species, seawater temperature is one of the main driving forces of biological processes, with consequences at higher levels of organization such as population and ecosystem. In this study, we analysed differences in maximum carapace width (CWmax), size at maturation, relative size at maturation, and duration of the reproductive season for the green crab (Carcinus maenas) along a temperature gradient. An extensive review of bibliographic data was performed on studies published between 1962 and 2020, gathering C. maenas data from 55 different populations, spread over 20 degrees of latitude and 14.2 °C of sea surface temperature (SST). In addition, green crab data were collected at five different lagoons and estuaries along the continental Portuguese coast. The relationship between average SST and CWmax, age of maturation, reduction of size at maturation, and duration of egg bearing was analysed to understand the role of SST in driving variation in these C. maenas characteristics across a latitudinal gradient. There was a significant relationship between SST and CWmax for males and SST and CW of females at maturation, respectively. The results extrapolate for each local projected temperature increase caused by climate change and suggest an effect on the morphometric and reproductive traits of C. maenas across regions. These changes comprise an overall reduction in C. maenas body size, an enlargement of the reproductive season, a shortening in the duration of larval developmental time, and a decrease in the relative size of crabs at maturation. Secondary consequences on the fecundity and connectivity of populations are discussed.
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