species distributions OBIS data
Species abundance distributions (SADs) depict the relative abundance of the species present in a community and describe one of the most fundamental patterns of species diversity. In our recent study, we analysed over 100 datasets covering different taxa and habitats, and showed that c. 15% of the SADs were multimodal with strong support, indicating that multimodality is a more common pattern than currently appreciated. We also showed that this pattern is more prevalent for communities encompassing broader spatial scales or greater taxonomic diversity, suggesting that multimodality increases with ecological heterogeneity. Our results emphasize the need for macroecological theories to include multimodality in the range of SADs they predict. Furthermore, differences in SAD shape across different scales provide important insights into the current endeavour of biodiversity scaling. OBIS was an invaluable source of high quality data, including metadata, from where we retrieved 25 datasets that met our selection criteria. Being able to access the data in a centralized repository was instrumental in terms of gathering appropriate data in a timely manner.
Prevalence of multimodal species abundance distributions is linked to spatial and taxonomic breadth. Laura Henriques Antão, Sean R. Connolly, Anne E. Magurran, Amadeu Soares & Maria Dornelas. Global Ecology and Biogeography, 2016. DOI: 10.1111/geb.12532
species composition biodiversity change
The extent to which biodiversity change in local assemblages contributes to global biodiversity loss is poorly understood. 100 time series from biomes across Earth were analysed to see how diversity within assemblages is changing through time. They quantified patterns of temporal alpha diversity, measured as change in local diversity, and temporal beta diversity, measured as change in community composition. Contrary to their expectations, they did not detect systematic loss of a diversity. However, community composition changed systematically through time, in excess of predictions from null models. Heterogeneous rates of environmental change, species range shifts associated with climate change, and biotic homogenization may explain the different patterns of temporal alpha and beta diversity. Monitoring and understanding change in species composition should be a conservation priority.
This study, which appeared in Science, used 80 time series datasets from OBIS.
Dornelas, M.; Gotelli, N.J.; McGill, B.; Shimadzu, H.; Moyes, F.; Sievers, C.; Magurran, A.E. (2014). Assemblage time series reveal biodiversity change but not systematic loss. Science (Wash.) 344: 296-299. DOI 10.1126/science.1248484
ophiuroids deep sea
The deep ocean is the largest and least-explored ecosystem on Earth, and a uniquely energy-poor environment. The distribution, drivers and origins of deep-sea biodiversity remain unknown at global scales. Here we analyse a database of more than 165,000 distribution records of Ophiuroidea (brittle stars), a dominant component of sea-floor fauna, and find patterns of biodiversity unlike known terrestrial or coastal marine realms. Both patterns and environmental predictors of deep-sea (2,000–6,500m) species richness fundamentally differ from those found in coastal (0–20m), continental shelf (20–200m), and upper-slope (200–2,000m) waters. Continental shelf to upper-slope richness consistently peaks in tropical Indo-west Pacific and Caribbean (0–30°) latitudes, and is well explained by variations in water temperature. In contrast, deep-sea species show maximum richness at higher latitudes (30–50°), concentrated in areas of high carbon export flux and regions close to continental margins. We reconcile this structuring of oceanic biodiversity using a species–energy framework, with kinetic energy predicting shallow-water richness, while chemical energy (export productivity) and proximity to slope habitats drive deep-sea diversity. Our findings provide a global baseline for conservation efforts across the sea floor, and demonstrate that deep-sea ecosystems show a biodiversity pattern consistent with ecological theory, despite being different from other planetary-scale habitats.
ocean acidification pteropods
Pteropods, also called sea butterflies, are tiny snails living in the water column that play a critical role in various ecosystems as prey for a variety of predators. There is a great concern about the potential impact of global change – and particularly ocean acidification – on these organisms as they exhibit an external shell, which is sensitive to changes in ocean chemistry. To represent the impact of both ocean acidification and global warming on pteropods, risk indicators have been calculated for three widely spread taxa that are dominant in high latitudes (Limacina helicina), temperate (Limacina retroversa), and warm waters (Creseis spp.). To create the indicators, experimental and observational data on pteropods’ response to global change were coupled with models describing chemical (aragonite saturation state) and physical (temperature) conditions of the ocean at present, in 2030 and 2050, under the “business as usual” carbon dioxide (CO2) emission scenario (RCP 8.5) and the “two degree stabilization” CO2 emission scenario (RCP 4.5). The present results confirm that global change is a very serious threat for high latitude pteropods: by 2050 under the CO2 emissions scenario RCP 8.5, they likely will not be able to thrive in most of the Arctic Ocean and some regions of the Southern Ocean.
OBIS SEAMAP cetaceans
Cetaceans are protected worldwide but vulnerable to incidental harm from an expanding array of human activities at sea. Managing potential hazards to these highly-mobile populations increasingly requires a detailed understanding of their seasonal distributions and habitats. Pursuant to the urgent need for this knowledge for the U.S. Atlantic and Gulf of Mexico, we integrated 23 years of aerial and shipboard cetacean surveys, linked them to environmental covariates obtained from remote sensing and ocean models, and built habitat-based density models for 26 species and 3 multi-species guilds using distance sampling methodology.