Loading...
4 results
Search Results
Now showing 1 - 4 of 4
- Contribution of the seagrass Syringodium isoetifolium to the metabolic functioning of a tropical reef lagoonPublication . Olivé, Irene; García-Robledo, Emilio; Silva, João; Pintado-Herrera, Marina G.; Santos, Rui; Kamenos, Nicholas A.; Cuet, Pascale; Frouin, PatrickSeagrasses are gaining attention thanks to their metabolism and potential major role as carbon sinks, with further implications as nature-based solutions against climate change. Despite their recognized importance and the growing number of studies published, there is still a striking paucity of information on seagrass metabolism and contribution to biogeochemical cycles for some seagrass species and ocean areas. In this study we assessed the metabolic balance and nutrient cycling contribution of seagrasses to the benthic compartment of a tropical reef lagoon in Reunion Island, providing original information on a barely studied seagrass species (Syringodium isoetifolium) and a poorly studied ocean region (West Indian Ocean). We measured the net productivity, respiration and the metabolic balance in different components of the lagoon benthic compartment (i.e. seagrass, sediment, and benthic community) and the water-sediment nutrient benthic fluxes at differently impacted sites within the lagoon. The biogeochemical environmental variability, including inorganic and organic indicators of anthropogenic contamination, was also assessed at each site.Large spatial variability was detected in the metabolic balance of each benthic component assessed, also associated with the natural and/or anthropic-driven environmental variability found in the lagoon. The seagrass S. isoetifolium was net autotrophic across the lagoon and contributed to the lagoon benthic metabolism with net plant productivity exceeding by one order of magnitude the plant respiration. The lowest seagrass metabolism was detected at the impacted site. The metabolic balance of the sediment was heterotrophic but the high productivity of S. isoetifolium contributed to reducing the heterotrophy of the whole benthic community. The lagoon-wide benthic metabolic balance was slightly heterotrophic, but the associated uncertainty ranged from autotrophy to heterotrophy. Nutrient concentrations in the lagoon were low and the benthic community capacity for nutrient retention (uptake) and removal (denitrification and anammox) indicated potential for buffering moderate nutrient inputs into the lagoon. Organic contaminants of emerging concern (CECs) were low but detectable in the lagoon, especially in highly frequented beach areas, arising as an environmental quality indicator of interest.
- First humpback whale (Megaptera novaeangliae) re-sighting between Azorean waters and the Barents Sea (Murman coast, northwestern Russia)Publication . Santos, Rui; Martins, Rafael; Chaiko, Anton; Cheeseman, Ted; Jones, Lindsey S.; Wenzel, Frederick W.Humpback whales (Megaptera novaeangliae) are one of the most well studied baleen whales worldwide and one of the species targeted during the historic North Atlantic whaling period. Northwestern Russia (Barents Sea), a poorly studied region for humpbacks, is recognized as an important fshing area for their prey capelin (Mallotus villosus). In the last century, this fsh species collapsed, possibly due to overfshing both in Russian and Norwegian waters, which led to these governments imposing strict fshing restrictions. In past decades the southern part of the Barents Sea has faced warming ocean temperatures and less sea ice. Here, we present the frst humpback photographic match between the Azores and northwestern Russia (Murmansk, Barents Sea). A humpback whale sighted on 14 March 2019 in the Azorean waters, was resighted opportunistically on 21 June, 2019 of the Murman coast, Russia. The estimated distance between the two sites is approximately 6778 km, representing a migratory speed of 2.88 km·h−1. Strict regulations on the summer capelin fsheries in the Murman coastline and Barents Sea, along with global warming may lead to new habitats for both fsh prey and predators (i.e., humpback whales) to return to this region.
- The impact of touristic whale-watching on Delphinus Delphis and Tursiops truncatus in the Algarve Coast: combining acoustic analysis and land observationsPublication . Forli, Maria Julia; Peres dos Santos, Rui Pedro; Rodrigues, Alfredo; Castilho, RitaTouristic whale watching (WW) is an important socioeconomic activity worldwide. Recently, short and longterm impacts caused by WW have been reported for several cetacean species, including Delphinus delphis and Tursiops truncatus, the two most observed species in Portugal. Most of the operations in mainland Portugal are concentrated on the South Coast (Algarve). However, despite their importance for the region, studies focused on the impact of this activity on the animals are still scarce. We used acoustic behaviour analysis and land-based observations to determine the alterations in the vocalization patterns of these animals caused by WW vessels and the length of exposure to this stressor. We found WW presence significantly altered five out of six acoustic parameters of whistles, whistle rate, and whistle type distribution for D. delphis, whereas T. truncatus exhibited significant changes in three acoustic parameters. Conversely, T. truncatus significantly reduced echolocation click rates, while D. delphis did not show significant changes. We also found that the Central region of this coast is the most affected, with animals exposed to WW vessels for up to 38.9% of daylight hours. Furthermore, 66.7% of the observation time in this area had several vessels that exceeded the limit established by law. These results suggest that our study species are impacted by WW, while D. delphis is more affected during social behaviours, and T. truncatus is more affected during foraging activities. Both behaviours are biologically significant, and their disturbance might, in the long term, lead to adverse effects at the population level by decreasing reproductive success and fitness. A gap in knowledge, inadequate legislation and compliance issues threaten the development of a sustainable WW industry in the Algarve and might endanger local populations, therefore immediate attention is needed.
- Tour operators as a tool to improve information on data‐deficient cetacean speciesPublication . Peres dos Santos, Rui Pedro; Rodríguez, Yasmina; Sears, Richard; Magno, Ramiro; Castilho, RitaUnderstanding the distribution and behaviour of species is crucial for ecosystem assessment and economic evaluations. Despite global research efforts, some cetacean species or populations remain data deficient. False killer whales (Pseudorca crassidens) are among these species, possibly due to their pelagic behaviour and high mobility. This study focused on the Azorean Archipelago, an ecologically rich region influenced by the Gulf Stream and North Atlantic Current, where false killer whales have been regularly observed over the last decade by the whale watching operators. Using opportunistic data collection from tourist operators, we established the first long-term study of false killer whales in the NE Atlantic Ocean. Results revealed sightings between April and October, with a peak from July to September. False killer whale groups were observed interacting with other species, particularly bottlenose dolphins (Tursiops truncatus). The photo-identification analysis produced an individual catalogue and identified associations between individuals and groups. Four of these animals presented dorsal fin injury patterns suggestive of interactions with fishing gear. Open population capture-recapture (openCR) models estimated a population of 198 individuals in the research area. This study demonstrates the importance of opportunistic data collection in understanding poorly studied species. The findings contribute insights into false killer whale presence, behaviour and potential threats in the studied region. Future research should expand to winter data collection, comprehensive fishery interaction studies and population dynamics assessments for effective conservation efforts.