Historically, knowledge of marine environments has lagged behind that of terrestrial environments. In 2000, marine scientists gathered to discuss approaches to combat this problem; the direct result was the Census of Marine Life, an international and collaborative effort. The Census began in 2000 and ended in 2010, with the goal of understanding the diversity, distribution, and abundance of marine species throughout the world. One of the Census’s contributions to the understanding of the marine global species distribution was the Ocean Biogeographic Information System (iOBIS: http://iobis.org) – a distributed data system. OBIS-USA (http://www.USGS.gov/obis-usa/) is a member node of iOBIS serving species occurrence data for U.S. Waters or with U.S. funding. The U.S. Geological Survey hosts the OBIS-USA system and performs the work of incorporating data from multiple provider sources and feeding that data up to iOBIS. Upon the completion of the Census, OBIS-USA began modestly. In January 2011, OBIS-USA contained 6.5 million occurrence records. But recently, contributions to OBIS-USA have increased. Last year, OBIS-USA contained 7.2 million occurrence records.
Currently, the number of occurrence records in OBIS-USA has increased to 28 million spanning 174 datasets from 148 providers. The increase in occurrence records is due primarily to the 19 million absence records that were added to OBIS-USA in the past year. The addition of absence records allows for modeling techniques that use both presence and absence data, such as species distribution modeling (SDM). SDM techniques require absence data and with the paucity of absence data, most researchers resort to using pseudo-absences. The absence records OBIS-USA has made available not only add to our knowledge of distributions of marine species but also span a relatively large span of time from 1976 to 2011, allowing for temporal examinations of species distributions in addition to improving the accuracy of SDMs. With the increased accuracy of SDMs, researchers will be able to more adequately predict the effects of climate change, anthropogenic effects, and conservation efforts for marine species distributions.