Shortened food chain length in a fished versus unfished coral reef.

Direct exploitation through fishing is driving dramatic declines of wildlife populations in ocean environments, particularly for predatory and large-bodied taxa. Despite wide recognition of this pattern and well-established consequences of such trophic downgrading on ecosystem function, there have been few empirical studies examining the effects of fishing on whole system trophic architecture. Understanding these kinds of structural impacts is especially important in coral reef ecosystems-often heavily fished and facing multiple stressors.

Zinc stimulation of phytoplankton in a low carbon dioxide, coastal Antarctic environment: evidence for the Zn hypothesis.

The ocean acts as a carbon sink, absorbing carbon from the atmosphere and resulting in substantial uptake of anthropogenic CO emissions. As biological processes in the oceans such as net primary production (NPP) contribute significantly to this sink, understanding how they will shift in response to increasing atmospheric CO is necessary to project future ocean carbon storage capacity. Macronutrient and micronutrient resource limitation within the oceans regulates NPP, and while some micronutrients such as zinc (Zn) are present at very low concentrations, their ability to limit NPP has remained unclear.

Autonomous submersible multiport water sampler.

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.

Autonomous underwater pumping system.

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.

Automated multiport flow-through water pumping and sampling system.

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.

Living coral tissue slows skeletal dissolution related to ocean acidification.

Climate change is causing major changes to marine ecosystems globally, with ocean acidification of particular concern for coral reefs. Using a 200 d in situ carbon dioxide enrichment study on Heron Island, Australia, we simulated future ocean acidification conditions, and found reduced pH led to a drastic decline in net calcification of living corals to no net growth, and accelerated disintegration of dead corals. Net calcification declined more severely than in previous studies due to exposure to the natural community of bioeroding organisms in this in situ study and to a longer experimental duration.

Author Correction: Coral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications.

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.

Coral carbon isotope sensitivity to growth rate and water depth with paleo-sea level implications.

Although reef coral skeletal carbon isotopes (δC) are routinely measured, interpretation remains controversial. Here we show results of a consistent inverse relationship between coral δC and skeletal extension rate over the last several centuries in Porites corals at Fiji, Tonga, Rarotonga and American Samoa in the southwest Pacific. Beginning in the 1950s, this relationship breaks down as the atmospheric C Suess effect shifts skeletal δC > 1.

Recent history of persistent organic pollutants (PAHs, PCBs, PBDEs) in sediments from a large tropical lake.

Pb-dated sediment cores and surface sediments from Lake Chapala (LC), Mexico, were analyzed to assess the temporal trends in concentrations and fluxes of persistent organic pollutants (POPs: PAHs, PCBs and PBDEs). Total sediment concentrations of PAHs (95-1,482 ng g), PCBs (9-27 ng g) and PBDEs (0.2-2.

Acetoclastic Methanosaeta are dominant methanogens in organic-rich Antarctic marine sediments.

Despite accounting for the majority of sedimentary methane, the physiology and relative abundance of subsurface methanogens remain poorly understood. We combined intact polar lipid and metagenome techniques to better constrain the presence and functions of methanogens within the highly reducing, organic-rich sediments of Antarctica's Adélie Basin. The assembly of metagenomic sequence data identified phylogenic and functional marker genes of methanogens and generated the first Methanosaeta sp.

Examining the utility of coral Ba/Ca as a proxy for river discharge and hydroclimate variability at Coiba Island, Gulf of Chirquí, Panamá.

Panamá's extreme hydroclimate seasonality is driven by Intertropical Convergence Zone rainfall and resulting runoff. River discharge (Q) carries terrestrially-derived barium to coastal waters that can be recorded in coral. We present a Ba/Ca record (1996-1917) generated from a Porites coral colony in the Gulf of Chiriquí near Coiba Island (Panamá) to understand regional hydroclimate.

Bubble Stripping as a Tool To Reduce High Dissolved CO2 in Coastal Marine Ecosystems.

High dissolved CO2 concentrations in coastal ecosystems are a common occurrence due to a combination of large ecosystem metabolism, shallow water, and long residence times. Many important coastal species may have adapted to this natural variability over time, but eutrophication and ocean acidification may be perturbing the water chemistry beyond the bounds of tolerance for these organisms. We are currently limited in our ability to deal with the geochemical changes unfolding in our coastal ocean.

Positive and negative effects of a threatened parrotfish on reef ecosystems.

Species that are strong interactors play disproportionately important roles in the dynamics of natural ecosystems. It has been proposed that their presence is necessary for positively shaping the structure and functioning of ecosystems. We evaluated this hypothesis using the case of the world's largest parrotfish (Bolbometopon muricatum), a globally imperiled species.

Long-range atmospheric transport of persistent organic pollutants to remote lacustrine environments.

Concentrations, temporal trends and fluxes of persistent organic pollutants (POPs: PAHs, PCBs and PBDEs) were determined in soil and (210)Pb-dated sediment cores from remote lacustrine environments (El Tule and Santa Elena lakes) in rural areas of Central Mexico. In both areas, the concentrations of target analytes in soil and sediment samples were comparable and indicative of slightly contaminated environments. The prevalence of low-molecular-weight PAHs in soils suggested their mainly atmospheric origin, in contrast to the aquatic sediments where runoff contribution was also significant.

Conservation management options and actions: putative decline of coral cover at Palmyra Atoll, Northern Line Islands, as a case study.

Localised loss of live coral cover at Palmyra Atoll (central Pacific Ocean) has been attributed to increased temperature and/or sedimentation arising from alterations made to the lagoon system. It has been hypothesised that a causeway spanning the lagoon hinders water circulation, resulting in warmer and/or more turbid water flowing towards a site of high coral cover and diversity (Coral Gardens). Analyses of a multi-site and multi-year data set revealed no differences in mean temperature or turbidity values on either side of the causeway and provided no evidence of significantly warmer or more turbid water at Coral Gardens.

The roles of productivity and ecosystem size in determining food chain length in tropical terrestrial ecosystems.

Many different drivers, including productivity, ecosystem size, and disturbance, have been considered to explain natural variation in the length of food chains. Much remains unknown about the role of these various drivers in determining food chain length, and particularly about the mechanisms by which they may operate in terrestrial ecosystems, which have quite different ecological constraints than aquatic environments, where most food chain length studies have been thus far conducted. In this study, we tested the relative importance of ecosystem size and productivity in influencing food chain length in a terrestrial setting.

Assessing the effects of large mobile predators on ecosystem connectivity.

Large predators are often highly mobile and can traverse and use multiple habitats. We know surprisingly little about how predator mobility determines important processes of ecosystem connectivity. Here we used a variety of data sources drawn from Palmyra Atoll, a remote tropical marine ecosystem where large predators remain in high abundance, to investigate how these animals foster connectivity.

A short-term in situ CO₂ enrichment experiment on Heron Island (GBR).

Ocean acidification poses multiple challenges for coral reefs on molecular to ecological scales, yet previous experimental studies of the impact of projected CO₂ concentrations have mostly been done in aquarium systems with corals removed from their natural ecosystem and placed under artificial light and seawater conditions. The Coral-Proto Free Ocean Carbon Enrichment System (CP-FOCE) uses a network of sensors to monitor conditions within each flume and maintain experimental pH as an offset from environmental pH using feedback control on the injection of low pH seawater. Carbonate chemistry conditions maintained in the -0.

From wing to wing: the persistence of long ecological interaction chains in less-disturbed ecosystems.

Human impact on biodiversity usually is measured by reduction in species abundance or richness. Just as important, but much more difficult to discern, is the anthropogenic elimination of ecological interactions. Here we report on the persistence of a long ecological interaction chain linking diverse food webs and habitats in the near-pristine portions of a remote Pacific atoll.

Iron limitation of a springtime bacterial and phytoplankton community in the ross sea: implications for vitamin b(12) nutrition.

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 B(12) 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 B(12) nutrition.

The atmospheric lead record preserved in lagoon sediments at a remote equatorial Pacific location: Palmyra Atoll, northern Line Islands.

Anthropogenic lead (Pb) inputs to the atmosphere increased greatly over the past century and now dominate Pb supply to the oceans. However, the Pb content of sediments across the equatorial Pacific region is relatively unknown, and data exist only for deep sea sites where Pb deposition lags surface water inputs by up to a century. Here we present ICP-MS analyses of Pb of a core from a lagoon at Palmyra Atoll, northern Line Islands, that spans approximately the past 160 years.

Plants cause ecosystem nutrient depletion via the interruption of bird-derived spatial subsidies.

Plant introductions and subsequent community shifts are known to affect nutrient cycling, but most such studies have focused on nutrient enrichment effects. The nature of plant-driven nutrient depletions and the mechanisms by which these might occur are relatively poorly understood. In this study we demonstrate that the proliferation of the commonly introduced coconut palm, Cocos nucifera, interrupts the flow of allochthonous marine subsidies to terrestrial ecosystems via an indirect effect: impact on birds.

Extreme longevity in proteinaceous deep-sea corals.

Deep-sea corals are found on hard substrates on seamounts and continental margins worldwide at depths of 300 to approximately 3,000 m. Deep-sea coral communities are hotspots of deep ocean biomass and biodiversity, providing critical habitat for fish and invertebrates. Newly applied radiocarbon age dates from the deep water proteinaceous corals Gerardia sp.