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- Short-term effects of climate change on Planktonic Heterotrophic Prokaryotes in a temperate Coastal Lagoon: Temperature Is good, ultraviolet radiation Is bad, and CO2 Is neutralPublication . B. Barbosa, Ana; Mosley, Benjamin A.; M. Galvão, Helena; Domingues, Rita B.Planktonic heterotrophic prokaryotes (HProks) are a pivotal functional group in marine ecosystems and are highly sensitive to environmental variability and climate change. This study aimed to investigate the short-term effects of increasing carbon dioxide (CO2), ultraviolet radiation (UVR), and temperature on natural assemblages of HProks in the Ria Formosa coastal lagoon during winter. Two multi-stressor microcosm experiments were used to evaluate the isolated and combined effects of these environmental changes on HProk abundance, production, growth, and mortality rates. The isolated and combined effects of increased CO2 on HProks were not significant. However, HProk production, cellular activity, instantaneous growth rate, and mortality rate were negatively influenced by elevated UVR and positively influenced by warming. Stronger effects were detected on HProk mortality in relation to specific growth rate, leading to higher HProk net growth rates and abundance under elevated UVR and lower values under warming conditions.
- Characterization of small-scale fishing activity in Luanda Bay (Angola)Publication . Faria, Silvana; Macuéria, Marisa; Mosley, Benjamin A.; Teodosio, Maria; Baptista, VâniaLuanda Bay, the second largest bay and one of the most important ecosystems of the Angolan coast, supports many human activities. This bay supports a range of marine biodiversity that serves as a means of livelihood and source of income for more than fifty small-scale artisanal fisheries and collectors of worms and bivalve molluscs. The present study is the first record of this fishing activity in Luanda Bay and the objective was to characterize the resource exploitation in this bay based on field data obtained by distributing self-reported and structured questionnaires to the two fishing communities (fishermen and shellfish harvesters) in Luanda Bay: Luanda Island and Luanda Commercial Harbour. The results revealed that the two fishing communities used different vessel types during fishing activity. In the Luanda Island fishing community, the fishermen used rowboats (“Chata”) and motorboats, and in the Commercial Port of Luanda fishing community, they used an adapted vessel made of Styrofoam boards. The main gears were line/hooks (34.1%), shovel (25.0%), seine (9,1%), gillnet (6.8%), trawl (4.5%) and traps (2.3%). According to the local fishing communities, Pomadasys jubelini, Mugil cephalus, Dentex spp., Senilia senilis, Mactra glauca, Donax spp., Perna perna, and Lucinella divaricata were the predominant species. In relation to the earnings by fishing day, the Luanda Island community had a higher income (average: 14.4 ± 8.3 euros; maximum: 39.0 euros) than Luanda Commercial Harbour community (average: 8.4 ± 5.1 euros; maximum: 24.2 euros). Thus, the quality of life of the fishing communities seems to be highly depending on this activity.
- Duration, but not bottle volume, affects Phytoplankton Community Structure and growth rates in microcosm experimentsPublication . B. Domingues, Rita; Mosley, Benjamin A.; Nogueira, Patricia; Maia, Inês Beatriz; B. Barbosa, AnaIt is generally assumed that the larger the bottle volume, the longer the duration of phytoplankton microcosm experiments. We hypothesize that volume and duration are independent, as volume does not regulate the extension of the exponential growth phase. We conducted two microcosm experiments using 1, 2, and 8 L bottles, inoculated with phytoplankton collected in the Ria Formosa lagoon (SE Portugal) and incubated for 1, 2, 4, and 8 days. Phytoplankton net growth rates were estimated using chlorophyll a concentration and cell abundance, determined with epifluorescence and inverted microscopy. Results show that the experimental duration significantly affected net growth rates, independently of volume, with decreasing net growth rates with time. Regarding volume, we found significant, but weak, differences in net growth rates, and significant two-way interactions only for the larger-sized cells. No significant differences in net growth rates across the different volumes were detected for the smaller, most abundant taxa and for the whole assemblage. We conclude that duration, not volume, is the main factor to consider in microcosm experiments, and it should allow the measurement of responses during the exponential growth phase, which can be detected through daily sampling throughout the duration of the experiment.