Humans interact with the oceans in diverse and profound ways. The scope, magnitude, footprint and ultimate cumulative impacts of human activities can threaten ocean ecosystems and have changed over time, resulting in new challenges and threats to marine ecosystems. A fundamental gap in understanding how humanity is affecting the oceans is our limited knowledge about the pace of change in cumulative impact on ocean ecosystems from expanding human activities - and the patterns, locations and drivers of most significant change. To help address this, we combined high resolution, annual data on the intensity of 14 human stressors and their impact on 21 marine ecosystems over 11 years (2003-2013) to assess pace of change in cumulative impacts on global oceans, where and how much that pace differs across the ocean, and which stressors and their impacts contribute most to those changes. We found that most of the ocean (59%) is experiencing significantly increasing cumulative impact, in particular due to climate change but also from fishing, land-based pollution and shipping. Nearly all countries saw increases in cumulative impacts in their coastal waters, as did all ecosystems, with coral reefs, seagrasses and mangroves at most risk. Mitigation of stressors most contributing to increases in overall cumulative impacts is urgently needed to sustain healthy oceans.

The hypothesis that one or more biodiversity drops in the Phanerozoic eon, evident in the geological record, might have been caused by the most powerful kind of stellar explosion so far, known Gamma Ray Bursts (GRBs), has been discussed in several works. These stellar explosions could have left an imprint in the biological evolution on Earth and in other habitable planets. In this work, we calculate the short term lethality that a GRB would produce in the aquatic primary producers on Earth. This effect on life occurs because of ultraviolet (UV) retransmission in the atmosphere of a fraction of the gamma energy, resulting in an intense UV flash capable of penetrating tens of meters into the water column in the ocean. We focus on the action of the UV flash on phytoplankton as they are the main contributors to global aquatic primary productivity. Our results suggest that the UV flash could cause a significant reduction of phytoplankton biomass in the upper mixed layer of the world's oceans.

A key question when trying to understand the global carbon cycle is whether the oceans are net sources or sinks of carbon. This will depend on the production of organic matter relative to the decomposition due to biological respiration. Estimates of respiration are available for the top layers, the mesopelagic layer, and the abyssal waters and sediments of various ocean regions. Although the total open ocean respiration is uncertain, it is probably substantially greater than most current estimates of particulate organic matter production. Nevertheless, whether the biota act as a net source or sink of carbon remains an open question.

The Ocean Twilight Zone project combines exacting science, innovative technology, and broad engagement to turn knowledge into actions that improve understanding of our planet and how to live sustainably on it.

Over the past several decades marine conservation policy has supported the implementation of protected areas in ocean and coastal environments to restrict some elements of human use for ecological benefits. The appropriate extent of protection and the allowable uses are often the subject of public debate about marine protected area policy. Local community dynamics around marine protected area designation and management have been the subject of much ocean and coastal management social science research. However, broader public opinions and attitudes about marine protected areas are not well understood and are critical for managers seeking to maintain their public trust obligations in environmental management. This paper provides a model for understanding the attitudes and beliefs that foster public support for or opposition to marine protections. We explored the relationships between awareness, attitudes and beliefs towards coastal and marine resource issues and uses, and demographics among a sample of Oregon, USA residents (n = 459), and tested their influence on support for expanding Oregon's recently established marine reserves. We found that Oregonians have relatively low familiarity with Oregon's marine reserve system, but that familiarity did not influence public support for Oregon's marine reserves. Instead public support was lower among coastal residents and those with positive attitudes towards commercial fisheries, and higher for those concerned with the ecological integrity of Oregon's ocean and supportive of some limits to human uses of the ocean. Our findings highlight the need for managers to engage both coastal communities and the general public to make a case for the value of marine protected areas in safeguarding the public trust.

The hypothesis that one or more biodiversity drops in the Phanerozoic eon, evident in the geological record, might have been caused by the most powerful kind of stellar explosion so far known Gamma Ray Bursts (GRB) has been discussed in several works. These stellar explosions could have left an imprint in the biological evolution on Earth and in other habitable planets. In this work we calculate the short-term lethality that a GRB would produce in the aquatic primary producers on Earth. This effect on life appears because of ultraviolet (UV) retransmission in the atmosphere of a fraction of the gamma energy, resulting in an intense UV flash capable of penetrating tens of meters in the water column in the ocean. We focus on the action of the UV flash on phytoplankton, as they are the main contributors to global aquatic primary productivity. Our results suggest that the UV flash could cause a significant reduction of phytoplankton biomass in the upper mixed layer of the World Ocean.

National Ocean Service's Education Online tutorial on Corals

The ocean formed billions of years ago

Ocean worlds is the label given to objects in the solar system that host stable, globe-girdling bodies of liquid water-"oceans". Of these, the Earth is the only one to support its oceans on the surface, making it a model for habitable planets around other stars but not for habitable worlds elsewhere in the solar system. Elsewhere in the solar system, three objects-Jupiter's moon Europa, and Saturn's moons Enceladus and Titan-have subsurface oceans whose existence has been detected or inferred by two independent spacecraft techniques. A host of other bodies in the outer solar system are inferred by a single type of observation or by theoretical modeling to have subsurface oceans. This paper focusses on the three best-documented water oceans beyond Earth: those within Europa, Titan and Enceladus. Of these, Europa's is closest to the surface (less than 10 km and possibly less than 1 km in places), and hence potentially best suited for eventual direct exploration. Enceladus' ocean is deeper-5-40 km below its surface-but fractures beneath the south pole of this moon allow ice and gas from the ocean to escape to space where it has been sampled by mass spectrometers aboard the Cassini Saturn Orbiter. Titan's ocean is the deepest-perhaps 50-100 km-and no evidence for plumes or ice volcanism exist on the surface. In terms of the search for evidence of life within these oceans, the plume of ice and gas emanating from Enceladus makes this the moon of choice for a fast-track program to search for life. If plumes exist on Europa-yet to be confirmed-or places can be located where ocean water is extruded onto the surface, then the search for life on this lunar-sized body can also be accomplished quickly by the standards of outer solar system exploration.