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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.
- Coupling sea lavender (Limonium algarvense Erben) and green tea (Camellia sinensis (L.) Kuntze) to produce an innovative herbal beverage with enhanced enzymatic inhibitory propertiesPublication . Rodrigues, Maria João; Oliveira, M.; Neves, V.; Ovelheiro, Andreia; Pereira, C. A.; Neng, N. R.; Nogueira, J. M. F.; Varela, J.; Barreira, Luísa; Custódio, LuísaHerbal beverages containing mixtures of L. algarvense (LA) flowers and C. sinensis (CS) were prepared and their inhibitory properties towards enzymes related with Alzheimer's (acetyl-and butyrylcholinesterase) and Type-2 diabetes mellitus (alpha-amylase and alpha-glucosidase) were evaluated for the first time. Samples were also appraised for antioxidant capacity and phenolic contents by high-performance liquid chromatography with diode-array detection (HPLC-DAD). Both synergistic and antagonistic interactions were observed: LA samples (infusion: IC50 = 0.22 mg/mL; decoction: 0.39 mg/mL) had higher acetylcholinesterase inhibition than CS and mixtures resulted in stronger enzymatic inhibition. CS had the highest rat alpha-glucosidase inhibition (infusion: IC50 = 3.91 mg/mL; decoction: IC50 = 2.50 mg/mL), which decreased when combined with LA. LA and CS samples had strong antioxidant activity, whereas LA and CS mixtures exhibited higher OH center dot radical-scavenging (0.56 <= SE <= 1.07) and anti-lipid peroxidation capacity (0.39 <= SE <= 0.81). CS had higher phenolic contents (infusion: 209 mg/g DW; decoction: 169 mg/g DW) and its combination with LA increased the phenolic diversity of the mixtures. Our results indicate that LA and CS infusions and decoctions and their combinations have relevant in vitro neuroprotective, antidiabetic and antioxidant properties and could be further explored as potential innovative functional beverages able to reduce the progression of neurodegenerative diseases and diabetic complications, and to prevent oxidative stress and lipid oxidation related diseases. (c) 2017 SAAB. Published by Elsevier B.V. All rights reserved.
- 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.
- Effect of bait type on the octopus fishery in Algarve, Southern PortugalPublication . Leitão, Francisco; Bueno-Pardo, Juan; Ovelheiro, Andreia; Monteiro, J. N.; Nobre, Daniela; Teodosio, MAIn Algarve, southern Portugal, a fishery regulation was established forbidding the use of live crab as bait for the octopus fishing. Such a regulation was not established under a scientific fundament. The objective of this work was to identify if using live crab as bait affects the octopus fishery. Time series (1989–2015) were analysed in order to calculate octopus catch rates (as Landing Per Unit Effort or LPUE) and revenues (as revenue per unit effort or RPUE) before and after the crab bait ban in 2009 and also by bait type (crab and fish) before ban. Overall, total annual fishing effort decreased as result of the decreasing number of boats and fishing days in the local and coastal fleets. After the ban both the LPUE and RPUE increased, with total landings showing no change through time but mean landings per boat increased. Between 1989 and 2009, the mean monthly fishing effort in the coastal fleet was higher when crab bait was used (3.88%) in comparison to using fish bait (0.3%). This result is superimposed by the large inter annual variability between the local and coastal fleets (39.11%). In consequence, no substantial evidence was found indicating that crab bait produced high octopus catch rates, while fishing effort indicated that such high octopus catch rate and revenue increase was due to the decline of number of boats and fishing effort, that was decreasing significantly regardless of the bait type and fleet before to crab ban, and not to the bait type used during this period.
- Ecological sensitivity and vulnerability of fishing fleet landings to climate change across regionsPublication . Albo Puigserver, Marta; Bueno-Pardo, Juan; Pinto, Miguel; N. Monteiro, J.; Ovelheiro, Andreia; Teodosio, Maria; Leitão, FranciscoThe degree of exposure of fishing communities to environmental changes can be partially determined by the vulnerability of the target species and the landings composition. Hence, identifying the species that ecologically most contribute to the vulnerability of the landings are key steps to evaluate the risk posed by climate change. We analyse the temporal variability in intrinsic sensitivity and the ecological vulnerability of the Portuguese fisheries landings, considering the species proportions derived both from the weights and revenues. To account for the diversification of species of each fleet, we explored the species dependence of the fishery in combination with the vulnerability of them. The analyses were carried out separately for three fleet typologies and three regions. Opposite to what has been observed at a global scale, the ecological sensitivity of the fisheries landings between 1989 and 2015 did not display a decline across areas or fishing fleets. Considering each fleet independently, for trawling, where average vulnerability was lower than in the other fleets, the sensitivity of the landings increased since the 2000s. On the other hand, the high vulnerability found in multi-gear fleets was compensated by diversification of the species caught, while purse-seine fleets targeted low vulnerability species but presented a high fishery dependence on few species. The results highlight the importance of combining information on ecological vulnerability and diversification of fishing resources at a regional scale while providing a measure of the ecological exposure to climate change.
- Sustainable harvesting alone cannot prevent decline of the green crab fishery in PortugalPublication . Monteiro, João Nuno; Roa-Ureta, Ruben; Ovelheiro, Andreia; Teodosio, Maria; Leitão, FranciscoEstuarine fisheries are of high regional socio-economic importance worldwide, by providing an important livelihood for many families. The Portuguese green crab (Carcinus maenas) fishery was assessed using a socio-economic assessment to understand the importance of the fishery and a stock assessment analysis to determine the exploitation status of the fishery during 1960-2020. Fisher knowledge revealed that crab fishing was a family affair that provided a livelihood for hundreds of families directly targeting crabs, with catches exported to Spain during 1960-1990s, and in later years, crab demand increased as bait for octopus fishing. Despite its socio-economic importance, the fishery was regulated without a scientific basis and economic value of crabs remained similar through time. Annual landings never exceeded sustainable catch rates, but engagement in the crab fishery declined due to low economic value of crabs compared to other fisheries and regulatory hurdles. Consequently, the number of fishermen declined to 20-30 elderly men fishing on the largest estuaries, with the fishery currently on the verge of extinction. Fishers pointed to a reduction in the minimum landing size and enforcement of crab-specific trap regulations as ways to avert fishery decline. Such changes would stimulate recruitment of new crab fishers, while reducing fishing pressure on other estuarine resources through fisheries diversification.
- Biological traits and population dynamics for sustainable harvesting of Carcinus maenasPublication . Monteiro, João Nuno; Ovelheiro, Andreia; Maia, Francisco; Teodosio, Maria; Leitão, FranciscoResearch focusing on the biological patterns and population dynamics of Carcinus maenas has not been conducted for the purpose of fishery management along the European coastal systems. This has led to the implementation of fisheries management policies without scientific considerations, adversely affecting fishery profitability. To addrees this gap, we studied the crab species' population dynamics, reproductive biology, and growth patterns across different Portuguese lagoons and estuaries on a monthly basis from 2019 to 2021. Surveys were performed in the Southern (Ria Formosa lagoon and Ria Alvor estuary), Central (Sado river/estuary) and Northern regions (Ria Aveiro estuary) of Portugal. Monthly biological data was used to analyse size-frequency distributions, sex ratios, spawning seasons, recruitment pulses, estimate carapace width at first maturaty and biological growth parameters. It was observed that spawning occurs almost year-round in all systems, with a peak in the colder months, between September and March. In the southern regions of the Portuguese coast, the spawning period starts earlier than in the central and northern systems, with a higher sex ratio recorded for females in all systems. The carapace width at which 50 % (CW50) of individuals reach maturity is similar for both sexes, around 30 mm, a value below to the minimum landing size enforced in Portugal. The analysis of von Bertalanffy growth curves revealed a continuous recruitment with a peak during the colder months, with individuals reaching the size at maturation after six months. The fast growth and continuous recruitment leds to the existence of between four and six growth cohorts for both sexes across all system. The findings of this study can contribute to more effective fisheries management policies for C. maenas in Portugal, such as a reduction of the minimum landing size.
- Impact and size selectivity of fishing gears used in estuarine crab fisheriesPublication . Monteiro, João Nuno; Ovelheiro, Andreia; Teodosio, Maria; Leitão, FranciscoCrustacean fisheries have expanded in the last decade due to the high economic value of the species. However, estuarine crustacean fisheries remain poorly studied compared with marine crustacean fisheries. In Portugal, the European green crab ( Carcinus maenas) may become increasingly important for the fishing industry and seafood production in general, especially in the current context of overexploitation of estuarine traditional fisheries resources. The unknown ecological impact of crab fishing gear and its size-selectivity characteristics constrain gear regulations by fisheries authorities. We developed an integrated study over three years to analyse a C. maenas fishery in three Portuguese estuarine systems aiming to: 1) describe the fishing characteristics and modus operandi of the fishing gears; 2) analyse gear selectivity and catch rates; 3) analyse environmental impact of fishing gears; 4) Contribute to supporting better regulations for the fishery. Two types of crab fishing gear are used, box traps and drop nets. Daily catches of green crabs varied by gear, system, and month, with the highest catches observed in box traps during the warmest months. Selectivity studies indicate that a mesh size of 18 mm in box traps and 30 mm in drop nets would allow crabs larger than the minimum landing size (40 mm carapace width) to be targeted while maximising catch rates. However, regardless of the mesh size, the catch from both gears will need to be sorted to exclude juveniles from the catch. The bar spacing, which allows crabs to be sorted according to the minimum landing size, is 17 mm. Gears present none (drop nets) or low by-catch (220 g or 23 individuals/40 box traps), which was promptly discarded, indicating a low impact on estuarine communities. The methodology used in this study, which combines ecological impacts and technical gear issues (selectivity), can be directly applied to enforce regulations and improve sustainable exploitation of socio-economically important artisanal fisheries.