This week, we are happy to host two visiting scholars who will both present during a combined one hour seminar….

Talk 1. Vertical habitat compression for oceanic top predators (squids and sharks) in expanding oxygen minimum zones

Abstract: In certain regions of world’s oceans, as depth increases dissolved oxygen (DO) initially decreases to low values, but rises again, delimiting an oxygen minimum zone (OMZ). Hence, OMZs consist of a low­oxygen layer (“hypoxic dead-zone”) of water located at intermediate depths in the water column and are associated with the large primary production at the surface ocean and enhanced mesopelagic decomposition. While several studies have documented an on­going expansion of OMZs, primarily through shoaling closer to the surface, climate model predictions suggest a continuation of this trend in the future. As OMZs shoal, acute oxygen gradients act to compress the habitat of high­oxygen­demand pelagic predators (e.g. mako and blue sharks in the Eastern Tropical Atlantic – ETA) against the layer of hypoxic water. In general, at the ETA-OMZ, surface occupancy (0 – 250 m) was 27% higher, while space-use of deeper depths (> 600 m) by blue sharks was ~95% less when compared to areas outside the OMZ. A future (+ 50 years) vertical habitat compression of between ~30 to ~50 m for OMZ waters is also expected. Unexpected hypoxia tolerant species (e.g. jumbo squids in the Eastern Tropical Pacific) are also influenced by the OMZ expansion because of differences in prey and predator availability near the normoxic surface. Preliminary data also shows that in the fishing areas with OMZ, fishing effort is higher inside the OMZ when compared to waters outside. Also, fishing intensity (% of time fishing) is always highest inside OMZ waters when compared to normoxia, thus suggesting longliners spent less time searching for target shark species in the OMZ. Clearly, information regarding the influence of mid­water oxygen on habitat­use patterns and distribution of commercially important species should be considered for effective management. Without such behavioural and physiological data, it will be difficult to further assess present impacts and future risks from pelagic fisheries.

Biography: Dr. Rui Rosa graduated in Marine Biology by Faculty of Sciences, University of Lisbon, in 1999 and completed a PhD degree in Biology by the same institution in 2005. Subsequently, Rosa carried out his post-doctoral activities at Univ. Rhode Island (USA). Rosa has authored 132 papers in international peer review journals, some in top-ranked journals (including Nature Geoscience, PNAS, Proc. Royal Soc London, Global Ecology and Biogeography, Global Change Biology, among others), and some were highlighted in renowned media (such as BBC News, Discovery Channel, National Geographic, The New York Times, among others) as well as in European Commission Alerts. His main research areas include Environmental Physiology, Marine Ecology, Comparative Biochemistry and Global Environmental Change, with special interest on (big) cephalopods and sharks. He has been engaged in internationally-renowned evaluation programs, including those from the US National Science of Foundation (NSF), US National Geographic, and MIT Sea-Grants.

Talk 2. From neurons to ecosystems: how ocean warming and acidification affect cooperative interactions

Abstract: Cleaning mutualisms are key ecological components in coral reef ecosystems and crucial drivers of marine biodiversity and abundance. These mutualisms are one of the most common interspecific interactions worldwide, which involves a cleaner organism that removes and eats ectoparasites from their so-called “clients” (usually larger reef fish) in complex and cognitive demanding cooperative behaviours that can involve tactile stimulation and partner control. Here I present a project were we studied the effects of ocean warming and acidification on cooperative cleaning interactions from neurobiology and behaviour to biogeography and ecosystems. We used behavioural neuroendocrinology trials to access the effects of acidification and warming in cooperative interactions, ecological manipulations to understand the direct effects of cleaning in client fitness and acclimation capacity and species distribution modelling to determine future and present biogeography patterns of cooperative life. This project constitutes the first empirical evidence that cooperative interactions are affected by ocean warming and acidification (along with a suggested as the neurobiological mechanism for their breakdown), that cooperative interactions influence client fish biogeography in the future and affect client acclimation capacity to the ocean of tomorrow.

Biography: José is a PhD student at Rui Rosa Lab, under supervision of Rui Rosa (University of Lisbon, Portugal) and Alexandra Grutter (The Unversity of Queensland, Australia). He’s passionate about cooperation (mutualisms) mainly in marine ecosystems. He uses cleaner wrasses Labroides dimidiatus as models to unravel how the environment can modulate the behavioural and neuroendocrine mechanisms of these complex cooperative interactions. The main aim of his research is to use an integrative approach (combining ecology, physiology, immunology, neuroendocrinology and behavioural ecology) to study how these mutualisms cope with future scenarios of ocean warming and acidification. He conducts his experiments using both lab and field based methods at Laboratório Marítimo da Guia (Cascais, Portugal) and Lizard Island Research Station (Lizard Island, Australia), respectively.