Overwinter Phenology of Plants in a Polar Semi-desert

Arctic and temperate-latitude tundra plants must make efficient use of the growing season, because it is very short. A variety of leaf-development strategies permit growth in the cool summers. ... Winter phenology was observed under field conditions for 27 of 33 angiosperm species found on King Christian Island. ... The full significance of overwintering leaf condition and the variability of this pattern within the High Arctic needs further investigation

Formation of undulating seafloor bedforms during the Minoan eruption and their implications for eruption dynamics and slope stability at Santorini

The Minoan eruption of Santorini is one of the largest Holocene volcanic events and produced several cubic kilometers of pyroclastic flows emplaced on the submerged flanks of the volcano. Marine geophysical surveys reveal a multitude of undulating seafloor bedforms (USBs) around Santorini. While similar structures are known from other volcanoes worldwide, Santorini offers the unique opportunity to relate USB formation with volcanic processes during one of the best-studied volcanic eruptions worldwide. In this study, we combine high-resolution seismic reflection data with multibeam echosounder bathymetry to reveal the internal architecture of USBs around Santorini and to relate their morphological characteristics to formational processes. The USBs around Santorini were formed during the Minoan eruption and represent the seafloor expression of mass transport deposits. Three types of deposits differ in composition or origin. (1) Depositional USBs, which can only be found to the north of the island, where Minoan eruption ignimbrites reach their maximum thickness and the undulating topography is the result of thrusting within the deposit. (2) USBs related to slope failures of volcaniclastics from the entire Thera Pyroclastic Formation, which can be found east, south, and west of the island. (3) USBs associated with deep-seated deformation, which occurs on the southwestern flank along an area affected by rift tectonics and extends to a depth of more than 200 m below the seafloor. In cases (2) and (3), the USBs are formed upslope by block rotation and downslope by thrusting. Our study indicates that these processes may have contributed to the generation of the devastating Minoan tsunami. Since Santorini is located in one of the most tectonically active regions in the Mediterranean, capable of producing earthquakes with magnitude M7+, our study has important implications for hazard assessment. A strong earthquake located close to the island may have the potential to reactivate slope instabilities posing a previously undetected but potentially significant tsunami hazard

Maka Niu: A low-cost, modular imaging and sensor platform to increase observation capabilities of the deep ocean

The deep sea (&amp;gt;200 m) is vast, covering 92.6% of the seafloor and largely unexplored. Imaging and sensor platforms capable of surviving the immense pressures at these depths are expensive and often engineered by individuals and institutions in affluent countries as unique, monolithic vehicles that require significant expertise and investment to build, operate, and maintain. Maka Niu was co-designed with a global community of deep-sea researchers. It is a low-cost, modular imaging and sensor platform that leverages off-the-shelf commodity hardware along with the efficiencies of mass production to decrease the price per unit and allow more communities to explore previously unseen regions of the deep ocean. Maka Niu combines a Raspberry Pi single-board computer, a Pi Camera Module V2, and a novel pressure housing and viewport combination capable of withstanding 1,500 m water depth. Other modules, including high-lumen LEDs, can be engineered to use the same battery charging and control system and form factor, allowing for an ever-increasing number of capabilities to be added to the system. After deployment, imagery and sensor data are wirelessly uploaded to Tator, an integrated media management and machine learning backend for automated analysis and classification. Maka Niu’s mobile mission programming and data management systems are designed to be user-friendly. Here, Maka Niu is described in detail along with data and imagery recorded from deployments around the world.</jats:p

Evaluation of the modern submarine landscape off southwestern Turkey through the documentation of ancient shipwreck sites

The issue of damage to shipwreck sites caused by the operation of mobile fishing gear has only recently begun to be addressed by the archaeological community. However, the nature, extent, and intensity of this damage has yet to be quantified. Acoustic and video surveys conducted between 2008 and 2010 located and imaged sixteen ancient shipwrecks around the Bodrum and Datça Peninsulas, Turkey, many of which were heavily damaged by trawling activity. The results of this research illustrate the unfortunate reality that many wreck sites in the Aegean Sea are heavily damaged by modern fishing activities. Quantifying the extent and intensity of trawl scars on the seabed further reveals the geographic spread of damage in these areas. The results of these mapping projects call attention to the dismantling of cultural sites by the use of mobile fishing gear on the seabed. By comparing the number of broken artifacts on these wreck sites to other sites that have escaped the effects of trawling, such as those in the Black Sea, we see that shipwrecks that are or were at one time in areas of trawling activity show a considerable amount of damage. The location and condition of these wreck sites helps map and quantify past and recent trawling activity, and pinpoint areas on the shallow coastal shelf where additional trawling restrictions or protected zones may be able to help the preservation of archaeological material. © 2012 Elsevier Ltd

Cold Seeps Associated with a Submarine Debris Avalanche Deposit at Kick’em Jenny Volcano, Grenada (Lesser Antilles)

Remotely operated vehicle (ROV) exploration at the distal margins of a debris avalanche deposit from Kick’em Jenny submarine volcano in Grenada has revealed areas of cold seeps with chemosynthetic-based ecosystems. The seeps occur on steep slopes of deformed, unconsolidated hemipelagic sediments in water depths between 1952 and 2042 m. Two main areas consist of anastomosing systems of fluid flow that have incised local sediments by several tens of centimeters. No temperature anomalies were observed in the vent areas and no active flow was visually observed, suggesting that the venting may be waning. An Eh sensor deployed on a miniature autonomous plume recorder (MAPR) recorded a positive signal and the presence of live organisms indicates at least some venting is still occurring. The chemosynthetic-based ecosystem included giant mussels (Bathymodiolus sp.) with commensal polychaetes (Branchipolynoe sp.) and cocculinid epibionts, other bivalves, Siboglinida (vestimentiferan) tubeworms, other polychaetes, and shrimp, as well as associated heterotrophs, including gastropods, anemones, crabs, fish, octopods, brittle stars, and holothurians. The origin of the seeps may be related to fluid overpressure generated during the collapse of an ancestral Kick’em Jenny volcano. We suggest that deformation and burial of hemipelagic sediment at the front and base of the advancing debris avalanche led to fluid venting at the distal margin. Such deformation may be a common feature of marine avalanches in a variety of geological environments especially along continental margins, raising the possibility of creating large numbers of ephemeral seep-based ecosystems

Hydrothermal Venting and Mineralization in the Crater of Kick\u27em Jenny Submarine Volcano, Grenada (Lesser Antilles)

Kick\u27em Jenny is a frequently erupting, shallow submarine volcano located 7.5 km off the northern coast of Grenada in the Lesser Antilles subduction zone. Focused and diffuse hydrothermal venting is taking place mainly within a small (∼70 × 110 m) depression within the 300 m diameter crater of the volcano at depths of about 265 m. Much of the crater is blanketed with a layer of fine-grained tephra that has undergone hydrothermal alteration. Clear fluids and gas are being discharged near the center of the depression from mound-like vents at a maximum temperature of 180°C. The gas consists of 93–96% CO2 with trace amounts of methane and hydrogen. Gas flux measurements of individual bubble streams range from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5–35°C above ambient occurs throughout the depression and over large areas of the main crater. These zones are colonized by reddish-yellow bacteria with the production of Fe-oxyhydroxides as surface coatings, fragile spires up to several meters in height, and elongated mounds up to tens of centimeters thick. A high-resolution photomosaic of the inner crater depression shows fluid flow patterns descending the sides of the depression toward the crater floor. We suggest that the negatively buoyant fluid flow is the result of phase separation of hydrothermal fluids at Kick\u27em Jenny generating a dense saline component that does not rise despite its elevated temperature

Exploration of the Black, Aegean, and Mediterranean Seas Aboard E/V Nautilus

In the summer of 2012, the Exploration Vessel (E/V) Nautilus undertook a two-month expedition to the Black, Aegean, and Mediterranean Seas. The primary goal of the Nautilus is to create a focus of international leadership for the development and integration of leading-edge technologies, educational programs, field operations, and public outreach programs for ocean exploration, in partnership with the NOAA Office of Ocean Exploration, National Geographic Society, Office of Naval Research, and corporate partners. To do so, the program uses a complement of deep submergence vehicle systems and telepresence technologies to engage scientists, educators and the public, both at sea and ashore, allowing them to become integral members of the on-board exploration team. When discoveries are made, experts ashore are notified and brought aboard virtually within a short period of time to help guide shipboard response before the ship moves on. The 2012 expedition is comprised of four areas of interest. Extensive sidescan mapping took place off the Turkish coasts of the southern Black Sea and eastern Aegean Sea, and was followed by remotely operated vehicle (ROV) dives on targets of archaeological, geological, and biological interest. In the Black Sea, additional work was done on the porewater chemistry of the sediments in the oxic, suboxic, and anoxic zones. Nautilus returned to the Anaximander Seamounts, including Kazan, Amserdam, Thessaloniki, and Athina, to further explore active and formerly active seep sites located in 2010. Finally, based on biological and geological discoveries made on Eratosthenes Seamount in the eastern Mediterranean Sea, we returned to further study chemosynthetic vent communities and tectonic processes

Hydrothermal Venting and Mineralization in the Crater of Kick\u27em Jenny Submarine Volcano, Grenada (Lesser Antilles)

Kick\u27em Jenny is a frequently erupting, shallow submarine volcano located 7.5 km off the northern coast of Grenada in the Lesser Antilles subduction zone. Focused and diffuse hydrothermal venting is taking place mainly within a small (∼70 × 110 m) depression within the 300 m diameter crater of the volcano at depths of about 265 m. Much of the crater is blanketed with a layer of fine-grained tephra that has undergone hydrothermal alteration. Clear fluids and gas are being discharged near the center of the depression from mound-like vents at a maximum temperature of 180°C. The gas consists of 93–96% CO2 with trace amounts of methane and hydrogen. Gas flux measurements of individual bubble streams range from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5–35°C above ambient occurs throughout the depression and over large areas of the main crater. These zones are colonized by reddish-yellow bacteria with the production of Fe-oxyhydroxides as surface coatings, fragile spires up to several meters in height, and elongated mounds up to tens of centimeters thick. A high-resolution photomosaic of the inner crater depression shows fluid flow patterns descending the sides of the depression toward the crater floor. We suggest that the negatively buoyant fluid flow is the result of phase separation of hydrothermal fluids at Kick\u27em Jenny generating a dense saline component that does not rise despite its elevated temperature

Exploring Kick’em Jenny Submarine Volcano and the Barbados Cold Seep Province, Southern Lesser Antilles [in special issue: New Frontiers in Ocean Exploration: The E/V Nautilus 2014 Gulf of Mexico and Caribbean Field Season]

The seafloor in the southern Lesser Antilles island arc is an area of active volcanism, cold seeps, and mud volcanoes (Figure 1). The Caribbean’s most active submarine volcano, Kick’em Jenny (KEJ), lying only 190 m below the surface, last erupted in 2001. The seafloor near Trinidad and Tobago hosts an extensive province of mud volcanoes and colds seeps that are generated by compression of fluid-rich marine sediments as the Atlantic plate subducts beneath the Caribbean plate in the forearc of the Lesser Antilles (Westbrook et al., 1983; Olu et al., 1996). During exploration with Nautilus in 2013, cold seeps were also discovered to the west of KEJ on a large debris avalanche deposit that extends to depths of more than 2,000 m (Carey et al., 2014). Their origin in this unusual geologic setting was attributed to overpressuring of subsurface fluids caused by the catastrophic collapse of the volcano and subsequent fluid movement downslope