Loading...
8 results
Search Results
Now showing 1 - 8 of 8
- 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.
- 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.
- The ocean in a box: water density gradients and discontinuities in water masses are important cues guiding fish larvae towards estuarine nursery groundsPublication . Baptista, Vânia; Morais, Pedro; Costa, Eudriano; Cruz, Joana; Teodosio, MariaDiscontinuities and gradients in water density are predominant features that may guide coastal fish larvae towards their estuarine nursery grounds when within the influence of an estuarine plume (Lindeman et al. 2000; Atema et al. 2002; Kingsford et al. 2002; Hale et al. 2008; James et al. 2008). When larvae are away from the estuarine plume zone, larvae may follow patchy estuarine cues that may lead them towards or away from the estuarine nursery—i.e., infotaxis strategy (sensu Vergassola et al. 2007, see Teodósio et al. (2016) for details on its applicability to fish larvae). So, recreating any of such conditions with the existing experimental apparatuses is far from resembling the natural conditions. Nonetheless, scientists have been relying on existing apparatuses to advance our understanding of which environmental cues are prioritized by fish larvae to find their nursery grounds (Radford et al. 2012; Morais et al. 2017; O'Connor et al. 2017; Vicente et al. 2020), how they respond to the presence of conspecifics (Døving et al. 2006; Vicente et al. 2020), prey, and predators (Lecchini et al. 2005), and even how climate change may disrupt sensory-driven social behaviors and habitat-choice responses (Munday et al. 2009; Pecl et al. 2017; Pistevos et al. 2017; Rossi et al. 2018).
- 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.
- Ingestion of macroplastics by common dolphinfish (Coryphaena hippurus) in the Atlantic OceanPublication . Costa, Eudriano; Dias, June Ferraz; Madureira, Lauro Antônio Saint PastousThe anthropogenic impact of pollution by plastic debris has threatened marine life inhabiting benthic and pelagic habitats from the poles to the equa tor (e.g., Ryan and Moloney, 1993; Derraik, 2002; Thompson et al., 2004). The ingestion of plastics by marine organisms is an increasing global trend due to the increase of these polymers in the oceans (e.g., Lusher et al., 2013; Besseling et al., 2015; Lusher et al., 2015; Lusher et al., 2018; Ostle et al., 2019; Neto et al., 2020). After reaching marine ecosystems, plas tics can be found either in their large original size (i.e., macroplastic) or in small fragments (i.e., nanoplastics, microplastics, or mesoplastics) (Azevedo-Santos et al., 2019). Thus, the interaction of plastic debris with marine life is expected, and their ingestion has been documented in a wide range of marine organisms, including zooplankton, bivalves, fish, turtles, birds, and marine mammals (Azzarello and Van-Vleet, 1987; Lusher et al., 2015; Romero et al., 2015; Egbeocha et al., 2018). There are several possible reasons for the consumption of plastic debris by marine fish, includ ing mistaking plastic for food because the odor of plastic in the sea is like that of food (Savoca et al., 2017), confusing it with prey species associated with floating plastic material while feeding on them, and preying on smaller organisms that have previously ingested plastics (Possato et al., 2011; Varghese et al., 2013
- Effects of biological and environmental factors on the variability of Paralonchurus brasiliensis (Sciaenidae) density: An GAMLSS applicationPublication . Costa, Eudriano; Teixeira, Gustavo M.; Freire, Fúlvio A. M.; Dias, June F.; Fransozo, AdilsonThe hypothesis of this study was based on the premise that complex interactions between biological and environmental factors may explain variability in fish population dynamics. To test this, Paralonchurus brasiliensis (Sciaenidae), a keystone species associated with coastal waters, was used as a model fish species. Generalized Additive Models for Location, Scale and Shape were performed to evaluate relationships among biological and environmental variables. Fish biomass, repletion index (RI), hepatosomatic index (HSI), condition factor (K) and sex ratio was in models as biological factors whereas water temperature, salinity, organic matter, grain size and depth were included as environmental variables. The results revealed significant effects of biological and abiotic factors on population density of P. brasiliensis. The selected model explained 94% of the variability in the explanatory variables. Fish biomass, HSI and K were the most important biological factors, whereas temperature and organic matter were the most important abiotic factors. Variability in fish density suggests that HSI and K both could be used as an additional ecosystem indicator of environmental status (food availability) and fish population health. We also highlight the importance of using robust and flexible statistical methods to model fish population dynamics and the need to incorporate biological and environmental factors into fishery resource management.
- Characterising different artisanal fishing gears catches that operate in distinct habitats to assess ichthyofauna assemblages in Bons Sinais estuary, MozambiquePublication . Jeremias J. Mocuba; Eudriano F.S. Costa; Daniel Oliveira Mualeque; Maria Alexandra Teodósio; Francisco Leitão; Mocuba, Jeremias; Florêncio dos Santos Costa, Eudriano; Teodosio, Maria; Leitão, FranciscoMonitoring the ichthyofauna is crucial to detect changes in aquatic communities for fisheries management and conservation. This study aimed to identify the most effective gear for ichthyofauna studies in the estuary. Thus, the performance of the beach seine (active gear) and chicocota (fixed gear), common fishing gears used by artisanal fishers in the Bons Sinais estuary (BSE), were used to characterise fish assemblage structure. Monthly surveys were conducted at two fixed sample points of the BSE to assess the composition of the fish assemblage. The analysis revealed statistical differences in abundance, biomass, and the presence/absence of different species between gears regardless sampling months. At ecological level, differences among gears were explained by different modus operandi, technological features and also different sampling habitats where gears operate; beach seine is catching bottom-bound and littoral fish while Chicocota is sampling the pelagic assemblage of the mid-channels. The frequency of occurrence of the 13 most abundant species differed between gears. Both gears showed little size-selectivity, with the mean total length and mean body height of these species statistically differing between gears. A total of 92 fish species were identified. No statistical differences were observed among gears for species richness, diversity and evenness. Both fishing gears captured several local socio-economically important species in the BSE. In particular, 13 of the most important species accounted for more than 54% and 60% of the total abundance and biomass in beach seine and chicocota, respectively. The complementary use of fixed and active fishing gears for studying fish community structure in estuaries is recommended. This multi-gear sampling approach enhances the capacity to detect changes in fish communities and provides valuable data for fisheries management and conservation efforts.
- Characterising different artisanal fishing gears catches that operate in distinct habitats to assess ichthyofauna assemblages in Bons Sinais estuary, MozambiquePublication . Mocuba, Jeremias; Florêncio dos Santos Costa, Eudriano; Mualeque, Daniel Oliveira ; Teodosio, Maria; Leitão, FranciscoMonitoring the ichthyofauna is crucial to detect changes in aquatic communities for fisheries management and conservation. This study aimed to identify the most effective gear for ichthyofauna studies in the estuary. Thus, the performance of the beach seine (active gear) and chicocota (fixed gear), common fishing gears used by artisanal fishers in the Bons Sinais estuary (BSE), were used to characterise fish assemblage structure. Monthly surveys were conducted at two fixed sample points of the BSE to assess the composition of the fish assemblage. The analysis revealed statistical differences in abundance, biomass, and the presence/absence of different species between gears regardless sampling months. At ecological level, differences among gears were explained by different modus operandi, technological features and also different sampling habitats where gears operate; beach seine is catching bottom-bound and littoral fish while Chicocota is sampling the pelagic assemblage of the midchannels. The frequency of occurrence of the 13 most abundant species differed between gears. Both gears showed little size-selectivity, with the mean total length and mean body height of these species statistically differing between gears. A total of 92 fish species were identified. No statistical differences were observed among gears for species richness, diversity and evenness. Both fishing gears captured several local socio-economically important species in the BSE. In particular, 13 of the most important species accounted for more than 54% and 60% of the total abundance and biomass in beach seine and chicocota, respectively. The complementary use of fixed and active fishing gears for studying fish community structure in estuaries is recommended. This multigear sampling approach enhances the capacity to detect changes in fish communities and provides valuable data for fisheries management and conservation efforts.