Browsing by Author "Moura, Paula"
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- Age and growth of a highly successful invasive species: the Manila clam Ruditapes philippinarum (Adams & Reeve, 1850) in the Tagus Estuary (Portugal)Publication . Moura, Paula; Garaulet, Lucia L.; Vasconcelos, Paulo; Chainho, Paula; Costa, Jose Lino; Gaspar, MiguelThe Manila clam Ruditapes philippinarum (Adams & Reeve, 1850) was introduced in several regions worldwide where it is permanently established. In Portuguese waters, the colonisation of the Tagus Estuary by this invasive species coincided with a significant decrease in abundance of the native Ruditapes decussatus (Linnaeus, 1758). This study aimed to estimate the age and growth of the Manila clam, to compare the growth performance between R. philippinarum and R. decussatus in several locations worldwide, and to ascertain whether the Manila clam's growth patterns contributed to the extensive distribution of this invasive bivalve in the Tagus Estuary. The growth of R. philippinarum in the Tagus Estuary was described through the von Bertalanffy equation SLt=65.2[1-e(-0.34(t+0.93))],corresponding to a phi-prime index (phi') of 3.160 and an overall growth performance of 4.974. This growth performance is the second highest recorded for R. philippinarum worldwide and was much higher than that of R. decussatus from Portugal. This study confirmed that the Tagus Estuary presents near-ideal environmental conditions for growth of the Manila clam. R. philippinarum displayed clearly invasive behaviour, spreading widely and growing faster than the native R. decussatus, which certainly contributed to the decline of its populations in the Tagus Estuary.
- Habitat structure shaping megabenthic communities inhabiting subtidal soft bottoms along the Algarve coast (Portugal)Publication . Rufino, Marta M.; Pereira, Alexandre M.; Pereira, Fabio; Moura, Paula; Vasconcelos, Paulo; Gaspar, MiguelThe present study analysed the megabenthic diversity in subtidal soft bottoms and assessed the main environmental drivers of megabenthic community organisation along the Algarve coast (southern Portugal). We tested the hypothesis that megabenthic communities respond to the same environmental drivers than macrofauna. We found that similar to macrofauna, megafaunal communities were organised in relation to the depth of closure, light reaching the bottom, and the hydrodynamic conditions related with exposure within the shallower areas. The influence of the main river outflow prevailed over other drivers, but only up to 9 m depth. We found that seven different spatial units should be considered, each characterised by different indicator species. Additionally, among a total of 412 taxa collected between 4 and 50 m depth, we provide the characteristics of the 64 commonest species in terms of occurrence, frequency, distribution, abundance, bathymetric and sedimentary preferences, which constitutes most valuable information for ecosystem modelling. Megabenthic alpha diversity decreased with depth, contrary to evenness and was higher in the proximity of the river Guadiana and in highly exposed shores. We conclude that the megafauna, which is significantly quicker to collect and analyse, can provide an accurate alternative to macrofauna sampling, as their communities are shaped by the same drivers.
- Morphometric relationships, relative growth and roe yield of the sea urchin (Paracentrotus lividus) from the Portuguese coastPublication . Nicolau, Lídia; Vasconcelos, Paulo; Machado, Inês; Pereira, Fábio; Moura, Paula; Carvalho, André N.; Gaspar, MiguelSea urchin (Paracentrotus lividus) populations from the northwestern (Carreco) and southwestern (Aljezur) coasts of Portugal were surveyed to analyse and compare their morphometric relationships, relative growth (isometry vs. allometry) and roe yield. Specimens were hand-collected from intertidal rock pools and sampled monthly during two consecutive years (November 2010-November 2012). Overall, 1220 P. lividus larger than 40 mm in test diameter (542 from Carreco and 678 from Aljezur) were analysed during the study period. Morphometric relationships established between specimen size (test diameter, height and volume) and weight (total and gonad weight) were statistically significant and displayed high correlation coefficients (r = 0.484 - 0.974), with allometric coefficients ranging from b = 0.962 to 1.239 (linear variables) and from b = 2.541 to 3.437 (linear and ponderal variables). Sea urchins mean roe yield was significantly higher in Carreco (7.5 +/- 3.1%) than in Aljezur (6.8 +/- 3.5%) and varied depending on the sampling month. The present data on morphometric relationships, relative growth and roe yield was duly compared with previous studies available on these topics, through an exhaustive review covering the distributional range of P. lividus along the Atlantic Ocean and Mediterranean Sea.
- Reproductive activity and biochemical composition of the pullet carpet shell Venerupis senegalensis (Gmelin, 1791) (Mollusca: Bivalvia) from Ria de Aveiro (northwestern coast of Portugal)Publication . Joaquim, Sandra; Matias, Domitília; Matias, Ana Margarete; Moura, Paula; Arnold, William S.; Chícharo, Luís; Baptista Gaspar, MiguelThe present study characterizes the reproductive cycle of Venerupis senegalensis (=V. pullastra) from Ria de Aveiro (Portugal) as well as its nutrient storage and exploitation strategy. The reproductive cycle followed a seasonal cycle that correlated negatively with sea surface temperature, and comprised a ripe stage in winter followed by a spawning period that began in late winter and ended in the early summer. This extended spawning may be an advantageous strategy for the species because it ensures a continuous supply of settlers. Gametogenesis began in late summer/early autumn and intensified with the decrease in temperature during autumn. The condition index increased even during the spawning period, which indicates that there is rapid recovery and that reserves are accumulated during late summer and used later in the gametogenic process. Proteins did not contribute significantly to gametogenesis and the glycogen pattern is typical of conservative species, since gametogenesis depends largely on the amount of glycogen stored. The lipid storage and utilization cycle showed that gametogenesis took place in autumn/winter and that energy reserves were accumulated in summer.
- Reproductive cycle of the commercially harvested sea urchin (Paracentrotus lividus) along the western coast of PortugalPublication . Machado, Ines; Moura, Paula; Pereira, Fabio; Vasconcelos, Paulo; Gaspar, MiguelHarvested populations of the sea urchin (Paracentrotus lividus) from the northwestern (Carreco) and southwestern (Aljezur) coasts of Portugal were surveyed to describe the species reproductive cycle and assess possible relationships with geographical location and seawater temperature. Individuals were sampled monthly to analyze gonad histology, mean gonadal index (GI), and gonadosomatic index (GSI) during 2 consecutive years (November 2010-November 2012). Both populations presented an annual reproductive cycle, with synchronous gonad maturation and gamete release between sexes. Gonad maturation occurred throughout autumn-winter, followed by a single but prolonged spawning season during spring-summer. The duration of the spawning season displayed a latitudinal gradient likely related to the north-south increasing trend in seawater temperature, with the northwestern population (Carreco) exhibiting a shorter spawning period compared to the southwestern population (Aljezur). The timing and duration of the spawning season was compared with several populations throughout the distributional range of P. lividus in the Atlantic Ocean and Mediterranean Sea. In the population from Carreco, the size at first sexual maturity (test diameter = 35.9 mm) was considerably smaller than the minimum conservation reference size (MCRS) of 50 mm test diameter legally established for P. lividus. This study confirms that sustainable exploitation depends on harvesters' awareness of and compliance with the MCRS and provides useful information for the eventual establishment of a closed season in the harvesting of P. lividus.
- Reproductive cycle of the golden carpet shell (Polititapes aureus) in the Ria Formosa lagoon (southern Portugal)Publication . Moura, Paula; Matias, Ana Catarina; Vasconcelos, Paulo; Roque, Cláudia; Joaquim, Sandra; Matias, Domitília; Gaspar, MiguelThe present study described the gametogenesis and assessed the pattern of energy storage throughout the reproductive cycle of the golden carpet shell (Polititapes aureus) from the Ria Formosa lagoon (southern Portugal). Monthly sampling was performed for two years (March 2016–February 2018) and the study was based on gonad histology, complemented by the estimation of the mean gonadal index, body condition index and biochemical composition. The species’ reproductive cycle presented a seasonal pattern, with a resting period mainly between October and January and gametogenesis beginning around February– March. The spawning season of P. aureus was shorter in 2016 (June–September) than in 2017 (May–October). Furthermore, ripe individuals were very scarce (1.3%) in 2017 compared with the previous year (11.4%). Mean gonadal index (GI) reflected the species’ reproductive cycle and the body condition index (CI) and biochemical composition of the individuals exhibited high variation between years. Regarding the biochemical composition, proteins ranged between 190.6 and 595.2 μg mg−1 , glycogen from 5.7 to 102.6 μg mg−1 and total lipids between 31.6 and 80.7 μg mg−1 . The reproduction of P. aureus was strongly influenced by fluctuations in both seawater temperature and chlorophyll a, as reflected through the temporal variation in the gonadal cycle, condition index and biochemical composition. Overall, the information gathered in this study is valuable to propose scientifically based harvesting management measures for the long-term sustainable exploitation of this shellfish resource, further reinforcing the importance of implementing adaptive fishery management strategies to cope with global climate change.
- Shell morphology, morphometric relationships and relative growth of three topshell species (Gastropoda: Trochidae) from the Algarve Coast (Southern Portugal)Publication . Vasconcelos, Paulo; Santos, Agatha C. N.; Pereira, Fábio; Moura, Paula; Carvalho, André N.; Gaspar, MiguelThis study analysed the shell morphology, morphometric relationships and relative growth in three topshell species (Phorcus lineatus, Phorcus sauciatus and Steromphala umbilicalis) collected in the Algarve coast (southern Portugal). A total of 1382 individuals were sampled (465 P. lineatus, 447 P. sauciatus and 470 S. umbilicalis) and all species comprised individuals with broad size and weight ranges. Morphometric relationships were established between linear (shell height, width, spire height, aperture height, aperture width) and ponderal (total weight) variables, whose relative growth (isometry vs. allometry) was analysed to assess variation throughout the species ontogeny. All morphometric relationships were highly significant (P < 0.001) and displayed invariably high correlation coefficients (r = 0.828 to 0.977), presenting mostly negative allometries (77.8%), distantly followed by positive allometries (16.7%) and by isometric growth (5.5%). In addition, four morphometric indices (sphericity, conicity, aperture roundness and density) were calculated to further describe and discern variation in shell shape in these topshell species. Moreover, this study provides a useful compilation and comparison of morphometric relationships, indices and relative growth features, thus improving the knowledge currently available on these subjects for P. lineatus, P. sauciatus and S. umbilicalis.
- Size at sex change and reproductive cycle of the limpets Patella vulgata and Patella ulyssiponensis (Mollusca: Patellogastropoda) from intertidal rocky shores of the Algarve coast (southern Portugal)Publication . Vasconcelos, Paulo; Umapathy, Uthesh; Moura, Paula; Pereira, Fábio; Carvalho, André N.; Gaspar, MiguelThis study describes the reproductive cycle of the common limpet (Patella vulgata) and rough limpet (Patella ulyssiponensis) from the Algarve coast (southern Portugal). Individuals of both species were sampled monthly during two consecutive years, and subjected to gonad histology and calculation of the mean gonadal index (GI). Both species had balanced sex ratios (P. vulgata = 1M: 0.98F; P. ulyssiponensis = 1M: 1.03F), similar size-frequency distribution between sexes, and equivalent mean shell lengths (SL) and total weights (TW) between males and females. In these protandrous hermaphrodites, the estimated size at sex change was slightly smaller in P. vulgata (SL50 approximate to 29 mm) than in P. ulyssiponensis (SL50 approximate to 36 mm). The reproductive cycles of both species were characterised by a main spawning season in early spring to early summer, sometimes including subsidiary spawning events. A comparison of the main spawning season throughout the species distributional ranges revealed that populations of P. vulgata and P. ulyssiponensis from southern Portugal have later spawning periods than other populations from the northeastern Atlantic Ocean. The present information is relevant for conservation purposes and for the proposal of management measures for the harvesting activity targeting P. vulgata and P. ulyssiponensis in southern Portugal.