Search

Coral reef sessile organisms inhabiting cryptic spaces and cavities of the reef matrix perform vital and varied functional roles but are often understudied in comparison to those on exposed surfaces. Here, we assess the composition of cryptobenthic taxa from three remote tropical reef sites (Central Indian Ocean) alongside a suite of in situ environmental parameters to determine if, or how, significant patterns of diversity are shaped by local abiotic factors. To achieve this, we carried out a point-count analysis of autonomous reef monitoring structure (ARMS) plate images and employed in situ instrumentation to recover long-term (12 months) profiles of flow velocity, wave heights, temperature, dissolved oxygen, and salinity, and short-term (3 weeks) profiles of light and pH. We recovered distinct environmental profiles between sampling sites and observed that ocean-facing reefs experienced frequent but short-lived cooling internal wave events and that these were key in shaping in situ temperature variability. By comparing temperature and wave height profiles recovered using in situ loggers with ex situ models, we discovered that global satellite products either failed to recover site-specific profiles or both over- and underestimated actual in situ conditions. We found that site choice and recruitment plate face (top or bottom) significantly impacted the percentage cover of bryozoans, gastropods, soft and calcified tube worms, as well as crustose coralline algae (CCA) and fleshy red, brown, and green encrusting macroalgae on ARMS. We observed significant correlations between the abundance of bryozoans, CCA, and colonial tunicates with lower mean temperature and higher mean dissolved oxygen profiles observed across sites. Red and brown encrusting macroalgae abundance correlated significantly with medium-to-high flow velocities and wave height profiles, as well as higher pH and dissolved oxygen. This study provides the first insight into cryptobenthic communities in the Chagos Archipelago marine-protected area and adds to our limited understanding of tropical reef sessile communities and their associations with environmental parameters in this region. With climate change accelerating the decline of reef ecosystems, integrating analyses of cryptobenthic organisms and in situ physicochemical factors are needed to understand how reef communities, if any, may withstand the impacts of climate change.

The Adélie Basin is a relatively small (∼1600 km2), semi-enclosed continental shelf bathymetric depression located adjacent to the Wilkes Subglacial Basin, a basin underlying a sector of the East Antarctic Ice Sheet that contains ∼3–4 m sea level equivalent of ice. Located within the Adélie Basin is a ∼184 m thick laminated sediment deposit, the Adélie Drift, ideal for examining regional changes in ice sheet and ocean dynamics. Here, we examine the ratio of reactive beryllium-10 to reactive beryllium-9 ((10Be/9Be)reac) in a marine sediment core obtained from the Adélie Drift to assess these changes during the Holocene epoch (11.7 ka BP to present). The (10Be/9Be)reac record provides insight into changes in freshwater input, primary productivity, and scavenging efficiency, while removing the influence of particle size on 10Be concentration. During the early Holocene, (10Be/9Be)reac ratios indicate increased meltwater discharge from ca. 11.7 to 10 ka BP, as grounded ice retreated from the Adélie Basin and adjacent bathymetric highs. After ∼10 ka BP, beryllium isotopes are influenced by scavenging efficiency and dilution controlled by ocean currents and accumulation rate, operating alongside meltwater input, suggesting there are additional factors to consider when using (10Be/9Be)reac as a proxy for ice shelf cover and glacial dynamics.

Rising anthropogenic CO2 levels in the atmosphere are resulting in ocean acidification which may impact coral growth rates. Here, the authors quantify the relationship between water depth and δ13C compositions of South Pacific corals from the pre-industrial era, and their results should lead to improvements in the precision of sea level reconstructions using fossil corals.

Oceanography and limnology projects often require the collection of water samples for chemical analysis. Manual water sample collection is labor-intensive and often difficult, especially in remote locations or during nighttime hours. Here we describe a compact and inexpensive autonomous submersible multiport water sampler (AutoSampler) that is largely fabricated with off-the-shelf parts making it easier to build and maintain. The system can collect up to 12 discrete samples at user controllable times or intervals and is operated using open source Arduino hardware and software that can be user modified to meet deployment requirements. While the underwater pressure housing presented here is custom built from readily available materials, there are many commercially available pressure case options that can be used as a substitute. The electronic mounting plates and battery pack are designed so that they can easily be adapted to fit into other pressure case housings. Samples can be collected into bags or syringes and sample volume is set by adjusting how long the peristaltic pump is actuated. This AutoSampler allows research that would otherwise be too labor-intensive or logistically difficult to conduct, especially in remote locations.

We present an inexpensive autonomous underwater pumping system that is lightweight, compact, independent, and versatile, making it easy to deploy in a multitude of settings. This system can be used to pump water into discrete and flow-through sensor systems. With the exception of the custom built pressure case housing, this system can be fabricated with off-the-shelf parts, making it easier to maintain. This system uses open source Arduino software code for easier customization and operations. The electronics and battery pack used to power this system can be adapted to fit into commercially available pressure case housings.

Flow-through systems are often used in aquarium and aquaculture facilities, laboratories, and aboard research vessels and other mobile systems to collect, analyze, and monitor water properties as they vary across time and location. These systems most often intake water from a single source and deliver it to a suite of flow-through sensors after which waste water either exits the system or is recirculated back to the source. Here we describe a system that is designed to take water from multiple sources via a multiport valve manifold and deliver it to a common sample stream, facilitating analysis by a single suite of flow-through and probe type sensors. Build cost depends on the manifold design and the number of valves, but generally under $9000. The inclusion of a Free Surface Interface Cup (FSIC) allows probe type sensors or sample “sippers” that require unpressurized conditions to be utilized down-stream of the pumping system and manifold. With the exception of the multiport sampling manifold, all components of this system are available off-the-shelf, simplifying construction, service, and maintenance. The operating system code is open source and based on the Arduino platform, enabling users to customize the code to better fit their requirements.

Optical instruments can rapidly determine numbers and characteristics of water column particles with high sensitivity. Here we show the usefulness of optically assessed total particle volume below the main pycnocline to estimate carbon export in two systems: the open subarctic North Atlantic and the Ross Sea, Antarctica. Both regions exhibit seasonally high phytoplankton production and efficient export (i.e., a strong biological pump). Total particle volumes in the mesopelagic (200–300 m) were significantly correlated with those in the overlying surface mixed layer (50–60 m), indicating that most particles at depth reflect export from the surface. This connectivity, however, is modulated by the physical structure of the water column and by particle type (e.g., the presence of colonies of the haptophyte Phaeocystis antarctica versus diatoms). Evidence from both regions show that a strong pycnocline can delay or may even prevent particles from settling to deeper layers, which then succumb to disintegration, and microbial and zooplankton consumption. Strong katabatic winds in the Ross Sea may deepen the mixed layer, causing a rapid transfer of particles to mesopelagic depths through the mixed-layer pump. Independent estimates of seasonally integrated export production in the Ross Sea, based on upper water column carbon mass balance, were significantly correlated (in the order of shared variance) with (1) total particle volumes from images, (2) particulate organic carbon, and (3) chlorophyll fluorescence, all recorded at a depth range of 200–300 m. Carbon export was not significantly correlated with particle abundance measured by a Coulter counter at the same depth range. Measuring total particle volume below the primary pycnocline is therefore a useful approach to estimate carbon export at least in regions characterized by seasonally high particle export.

Gaelic-speaking emigrants brought with them a massive body of oral tradition, including a rich and varied corpus of song–poetry, and many of the emigrants were themselves highly skilled song-makers. Elegies were a particularly prominent genre that formed a crucially important aspect of the sizeable amount of panegyric verse for members of the Gaelic aristocracy, which is a tradition dating back to the Middle Ages. This contribution will demonstrate that elegies retained a prominent place in the Gaelic tradition in the new world Gaelic communities established in many parts of Canada and in particular in eastern Nova Scotia. In many respects, the tradition is a conservative one: there are strong elements of continuity. One important difference is the subjects for whom elegies were composed: in the new world context, praise for clan chiefs and other members of the traditional Gaelic aristocracy were no longer of relevance, although a small number were composed primarily out of a sense of personal obligation for patronage shown in the Old Country. Instead—and as was increasingly happening in the nineteenth century in Scotland, as well—the deaths of new community leaders, including clergy, and other prominent Gaels were recorded in verse. The large number of songs composed to mark the deaths of community members is also important—particularly young people lost at sea and in other tragic circumstances, occasionally in military service, and so forth. In these song–poems, we see local poets playing a role assumed by song-makers throughout Gaelic-speaking Scotland and Ireland: that of spokespeople for the community as a whole.

Antarctic pack ice is inhabited by a diverse and active microbial community reliant on nutrients for growth. Seeking patterns and overlooked processes, we performed a large-scale compilation of macro-nutrient data (hereafter termed nutrients) in Antarctic pack ice (306 ice-cores collected from 19 research cruises). Dissolved inorganic nitrogen and silicic acid concentrations change with time, as expected from a seasonally productive ecosystem. In winter, salinity-normalized nitrate and silicic acid concentrations (C*) in sea ice are close to seawater concentrations (Cw), indicating little or no biological activity. In spring, nitrate and silicic acid concentrations become partially depleted with respect to seawater (C* < Cw), commensurate with the seasonal build-up of ice microalgae promoted by increased insolation. Stronger and earlier nitrate than silicic acid consumption suggests that a significant fraction of the primary productivity in sea ice is sustained by flagellates. By both consuming and producing ammonium and nitrite, the microbial community maintains these nutrients at relatively low concentrations in spring. With the decrease in insolation beginning in late summer, dissolved inorganic nitrogen and silicic acid concentrations increase, indicating imbalance between their production (increasing or unchanged) and consumption (decreasing) in sea ice. Unlike the depleted concentrations of both nitrate and silicic acid from spring to summer, phosphate accumulates in sea ice (C* > Cw). The phosphate excess could be explained by a greater allocation to phosphorus-rich biomolecules during ice algal blooms coupled with convective loss of excess dissolved nitrogen, preferential remineralization of phosphorus, and/or phosphate adsorption onto metal-organic complexes. Ammonium also appears to be efficiently adsorbed onto organic matter, with likely consequences to nitrogen mobility and availability. This dataset supports the view that the sea ice microbial community is highly efficient at processing nutrients but with a dynamic quite different from that in oceanic surface waters calling for focused future investigations.

The original version of the Source Data associated with this Article included an error, in which the ‘Fiji AB d13C-Suess’ data point and the ‘TNI2 d13C-Suess Effect’ data point for the year ‘1950.5’ where incorrectly omitted from the Figure 3 tab. The missing values are ‘−0.24’ and ‘−0.64’, respectively. The HTML has been updated to include a corrected version of Source Data.

Scientific and political interests at the poles are significant and rapidly increasing, driven in part by the effects of climate change and emerging geopolitical realities. The polar regions provide important services to global ecosystems and humankind, ranging from food and energy to freshwater and biodiversity. Yet the poles are experiencing changes at rates that far outpace the rest of the planet. Coastal Arctic communities are impacted by climate change through coastal erosion, sea level rise, ice loss, and altered marine food webs, threatening the future of their subsistence lifestyle. Climate change has dramatically increased the melt rate of ice sheets and glaciers at both poles and has the potential to significantly raise sea level worldwide. Oil and gas drilling as well as transportation in the Arctic have reached all-time high levels, in part because of reduced sea ice cover. Tourism is a growing industry at both poles, bringing more than 20,000 tourists each year to the western Antarctic Peninsula alone. The collateral effects of human activities include the potential for pollution of the marine environment, particularly through spills of hydrocarbons. Our ability to understand the effects of such activities and mishaps is limited, particularly in ice-covered areas during winter.

The Ross Sea is home to some of the largest phytoplankton blooms in the Southern Ocean. Primary production in this system has previously been shown to be iron limited in the summer and periodically iron and vitamin B12 colimited. In this study, we examined trace metal limitation of biological activity in the Ross Sea in the austral spring and considered possible implications for vitamin B12 nutrition. Bottle incubation experiments demonstrated that iron limited phytoplankton growth in the austral spring while B12, cobalt, and zinc did not. This is the first demonstration of iron limitation in a Phaeocystis antarctica-dominated, early season Ross Sea phytoplankton community. The lack of B12 limitation in this location is consistent with previous Ross Sea studies in the austral summer, wherein vitamin additions did not stimulate P. antarctica growth and B12 was limiting only when bacterial abundance was low. Bottle incubation experiments and a bacterial regrowth experiment also revealed that iron addition directly enhanced bacterial growth. B12 uptake measurements in natural water samples and in an iron fertilized bottle incubation demonstrated that bacteria serve not only as a source for vitamin B12, but also as a significant sink, and that iron additions enhanced B12 uptake rates in phytoplankton but not bacteria. Additionally, vitamin uptake rates did not become saturated upon the addition of up to 95 pM B12. A rapid B12 uptake rate was observed after 13 min, which then decreased to a slower constant uptake rate over the next 52 hours. Results from this study highlight the importance of iron availability in limiting early season Ross Sea phytoplankton growth and suggest that rates of vitamin B12 production and consumption may be impacted by iron availability.

Although we share many aspects of our behaviour and bi­ology with our primate cousins, humans are, nonetheless, different in one crucial respect: our capacity to live in the world of the imagination. This is reflected in two core aspects of our behaviour that are in many ways archetypal of what it is to be human: religion and story-telling. I shall show how these remarkable traits seem to have arisen as a natural development of the social brain hypothesis, and the underlying nature of primate sociality and cognition, as hu­man societies have been forced to expand in size during the course of our evolution over the past 5 million years.