Centre for Environmental and Marine Studies

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Seabird diet analysis suggests sudden shift in the pelagic communities of the subtropical Northeast Atlantic

Publication . Romero, Joana; Catry, Paulo; Alonso, Hany; Granadeiro, José Pedro

The dynamics of the subtropical pelagic ecosystems of the Northeast Atlantic are still poorly known due to the high costs associated with sampling large oceanic areas. Top predators can be used as alternative low-cost samplers and indicators of the temporal variability of such systems. To study the variation in the composition of pelagic species through time in the broad Canary current region, we analysed foraging trips and regurgitations of Cory's shearwaters Calonectris borealis nesting on Selvagens islands, in 2008-2011 and 2016-2018. Fisheries data, oceanographic variables and the North Atlantic Oscillation were explored as possible explanatory variables for trends in behaviour and diet. Cory's shearwaters' diet, complemented by fisheries data, revealed marked changes in the composition of the pelagic fish communities. In 2016 there was a peak in the abundance of the Atlantic chub mackerel Scomber colias, followed by an explosive increase in the abundance of the Longspine snipefish Macroramphosus scolopax in 2017 and 2018, as deduced from the diet composition of the Cory's shearwater, and supported by fisheries data, in the broad oceanic area surrounding the Selvagens islands. Oceanographic variables did not show fluctuations correlated with these marked shifts in pelagic fish availability, the causes of which remain largely unknown. This study highlights the importance of the Atlantic chub mackerel and of the Longspine snipefish in the Madeira/Canary region and exemplifies the efficiency of avian predators in revealing rapid changes in pelagic communities of oceanic domains. Such trends and variations need to be better monitored and understood to measure the impact of ongoing global changes and to sustainably manage the marine environment and resources.

2021Journal article

Open access

Untangling causes of variation in mercury concentration between flight feathers

Publication . Gatt, Marie C.; Furtado, Ricardo Andrade; Granadeiro, José P.; Lopes, Daniel; Pereira, Eduarda; Catry, Paulo

Bird feathers are one of the most widely used animal tissue in mercury biomonitoring, owing to the ease of collection and storage. They are also the principal excretory pathway of mercury in birds. However, limitations in our understanding of the physiology of mercury deposition in feathers has placed doubt on the interpretation of feather mercury concentratoins. Throughout the literature, moult sequence and the depletion of the body mercury pool have been taken to explain patterns such as the decrease in feather mercury from the innermost (P1) to the outermost primary feather (P10) of the wing. However, it has been suggested that this pattern is rather a measurement artefact as a result of the increased feather mass to length ratio along the primaries, resulting in a dilution effect in heavier feathers. Here, we attempt to untangle the causes of variation in feather mercury concentrations by quantifying the mercury concentration as μg of mercury (i) per gram of feather, (ii) per millimetre of feather, and (iii) per day of feather growth in the primary feathers of Bulwer's Petrel Bulweria bulwerii chicks, effectively controlling for some of the axes of variation that may be acting in adults, and monitoring the growth rate of primary feathers in chicks. The mercury concentration in Bulwer's Petrel chicks' primaries increased from the innermost to the outermost primary for all three concentration measures, following the order of feather emergence. These observations confirm that the pattern of mercury concentration across primary feathers is not an artefact of the measure of concentration, but is likely an effect of the order of feather growth, whereby the earlier grown feathers are exposed to higher blood mercury concentrations than are later moulted feathers as a result of blood mercury depletion.

2021Journal article

Open access

Global political responsibility for the conservation of albatrosses and large petrels

Publication . Beal, Martin; Dias, Maria P.; Phillips, Richard A.; Oppel, Steffen; Hazin, Carolina; Pearmain, Elizabeth J.; Adams, Josh; Anderson, David J.; Antolos, Michelle; Arata, Javier; Arcos, José Manuel; Arnould, John P. Y.; Awkerman, Jill; Bell, Elizabeth; BELL, Mike; Carey, Mark; Carle, Ryan; Clay, Thomas A.; Cleeland, Jaimie; Colodro, Valentina; Conners, Melinda; Flores, Marta Cruz; Cuthbert, Richard; Delord, Karine; Deppe, Lorna; Dilley, Ben J.; Dinis, Herculano; Elliott, Graeme; De Felipe, Fernanda; Felis, Jonathan; Forero, Manuela G.; Freeman, Amanda; Fukuda, Akira; González-Solís, Jacob; Granadeiro, J. P.; Hedd, April; Hodum, Peter; Igual, Jose Manuel; Jaeger, Audrey; Landers, Timothy; Le Corre, Matthieu; Makhado, Azwianewi; Metzger, Benjamin; Militão, Teresa; Montevecchi, William A.; Pujol, Virginia Morera; Herrero, Leia Navarro; Nel, Deon; Nicholls, David; Oro, Daniel; Ouni, Ridha; Ozaki, Kiyoaki; Quintana, Flavio; Ramos, Raül; Reid, Tim; Reyes-González, José Manuel; Robertson, Christopher; Robertson, Graham; Romdhane, Mohamed Salah; Ryan, Peter G.; Sagar, Paul; Sato, Fumio; Schoombie, Stefan; Scofield, Richard; Shaffer, Scott; Shah, Nirmal Jivan; Stevens, Kim L.; Surman, Christopher; Suryan, Robert M.; Takahashi, Akinori; Tatayah, Vikash; Taylor, Graeme; Thompson, David R.; Torres, Leigh; Walker, Kath; Wanless, Ross; Waugh, Susan M.; Weimerskirch, Henri; Yamamoto, Takashi; Zajkova, Zuzana; Zango, Laura; Catry, Paulo

Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.

2021Journal article

Open access

Characterization of an extinct seabird colony on the island of Santa Luzia (Cabo Verde) and its potential for future recolonizations

Publication . Alho, Maria; Granadeiro, José P.; Rando, Juan Carlos; Geraldes, Pedro; Catry, Paulo

Islands worldwide have sufered seabird extinctions after the arrival of humans and the alien species they introduced. On Santa Luzia (Cabo Verde), an uninhabited island of 35 km2 ,the presence of an impressive quantity of petrel bones in coastal dunes suggested the previous existence of an important seabird colony. Yet, these remains had not been identifed and no seabird extinctions have been reported for the island. This paper characterizes the extinct seabird colony of Santa Luzia and discusses the chronology and possible causes of its demise. A total of 130 grid points in a 5 km2 area and 38 supplementary points within and outside the main study area were excavated to collect bone remains. A total of 1318 anatomical elements, identifed as White-faced Storm Petrel Pelagodroma marina eadesorum (85.3% of the minimum number of individuals, MNI), Boyd’s Shearwater Pufnus lherminieri boydi (11.8% MNI) and Cape Verde Storm Petrel Hydrobates jabejabe (2.9% MNI), were found in 18% of the sampling points, within 1.25 km2 . Neither of the two former species currently breeds on Santa Luzia. In addition, two bones of the Cape Verde Shearwater Calonectris edwardsii and Pterodroma sp. were detected in the supplementary points. Radiocarbon dating of White-faced Storm Petrel (n=10) and Boyd’s Shearwater bones (n=13) suggests that the colony probably went extinct during the frst half of the twentieth century. The recent extinction of these species on Santa Luzia might be consequent on the arrival of humans and their domestic animals on the island. We estimate that the extinct seabird populations must have been at least hundreds of thousand strong, far larger than current populations of the same species in Cabo Verde. We suggest that, following feral cat eradication, Santa Luzia has a signifcant potential for seabird restoration

2021Journal article

Open access

Environmental variability directly affects the prevalence of divorce in monogamous albatrosses

Publication . Ventura, Francesco; Granadeiro, José P.; Lukacs, Andor; Kuepfer, Amanda; Catry, Paulo

In many socially monogamous species, divorce is a strategy used to correct for sub-optimal partnerships and is informed by measures of previous breeding performance. The environment affects the productivity and survival of populations, thus indirectly affecting divorce via changes in demographic rates. However, whether environmental fluctuations directly modulate the prevalence of divorce in a population remains poorly understood. Here, using a longitudinal dataset on the long-lived black-browed albatross (Thalassarche melanophris) as a model organism, we test the hypothesis that environmental variability directly affects divorce. We found that divorce rate varied across years (1% to 8%). Individuals were more likely to divorce after breeding failures. However, regardless of previous breeding performance, the probability of divorce was directly affected by the environment, increasing in years with warm sea surface temperature anomalies (SSTA). Furthermore, our state-space models show that warm SSTA increased the probability of switching mates in females in successful relationships. For the first time, to our knowledge, we document the disruptive effects of challenging environmental conditions on the breeding processes of a monogamous population, potentially mediated by higher reproductive costs, changes in phenology and physiological stress. Environmentally driven divorce may therefore represent an overlooked consequence of global change.

2021Journal article

Open access