Environmental Predictors of Seabird Wrecks in a Tropical Coastal Area

Abstract

Beached bird surveys have been widely used to monitor the impact of oil pollution in the oceans. However, separating the combined effects of oil pollution, environmental variables and methodological aspects of beach monitoring on seabird stranding patterns is a challenging task. The effects of a comprehensive set of oceanographic and climatic variables and oil pollution on seabird strandings in a tropical area of Brazil were investigated herein, using two robust and innovative methods: Generalized Linear Mixed Models and Structural Equation Modeling. We assessed strandings of four resident seabird species along 480 km of beaches divided into 11 sampling areas, between November 2010 and September 2013. We found that increasing the distance from the nearest breeding island reduce the seabird stranding events. Storm activity and biological productivity were the most important factors affecting the stranding events of brown boobies Sula leucogaster, Cabot’s terns Thalasseus acuflavidus and kelp gulls Larus dominicanus. These species are also indirectly affected by warm tropical waters, which reduce chlorophyll-a concentrations. Beach surveys are, thus, useful to investigate the mortality rates of resident species near breeding sites, where individuals are more abundant and exposed to local factors associated with at-sea mortality. In contrast, conservation actions and monitoring programs for far-ranging seabird species are needed in more distant foraging areas. Furthermore, beach monitoring programs investigating the impact of oil pollution on seabirds need to account for the effects of environmental factors on stranding patterns. The present study also demonstrated that seabirds inhabiting tropical coastal waters are sensitive to climate conditions such as adverse weather, which are expected to increase in frequency and intensity in next decades.

A comprehensive survey of Aeromonas sp. and Vibrio sp. in seabirds from southeastern Brazil: outcomes for public health

“…Oral and cloacal swabs, and in some cases ocular (13), tracheal (1) and skin wounds (5) swabs, from all birds were collected, in duplicate. These 19 species of seabirds corresponded to 57Á5% of the taxa occurring in the region, according to Tavares et al (2016bTavares et al ( , 2017. The field activities were approved by the Instituto Chico Mendes de Conservac ßão da Biodiversidade.…”

Drivers affecting mammal community structure and functional diversity under varied conservation efforts in a tropical rainforest in Cameroon

“…We treated Site and site characteristics (Distance to villages, Distance to Dja River, Number of human signs and trails and Proportion of habitat type) in each sampling unit as fixed factors. We nested stretches in transects, and transects in Site, which we included as a random effect in our models, thus correcting for potential spatial autocorrelation (Tavares et al, 2015;Tavares, De Moura & Siciliano, 2016). In the models analysing FDis, FSpe and FOri, we used mammal abundance as weight as this can influence these dependent variables.…”

Traits Shared by Marine Megafauna and Their Relationships With Ecosystem Functions and Services

“…Information on the frequency and number of individuals stranded among sea turtles, pinnipeds, cetaceans, and seabirds has been used recently to quantify mortality patterns (Moura et al, 2016;Tavares et al, 2016;Flint et al, 2017). Carcasses found washed onshore can be collected easily and with low costs, and constitute a convenient source of information for assessing the distribution and variability of morphological, physiological, and demographical traits in relation to local environmental stressors (Spitz et al, 2006;Thompson et al, 2013;Amano et al, 2014;Fruet et al, 2015).…”