Food webs are comprised of a network of trophic interactions and are essential to elucidating ecosystem processes and functions. However, the presence of unknown, but critical networks hampers understanding of complex and dynamic food webs in nature. Here, we empirically demonstrate a missing link, both critical and variable, by revealing that direct predator-prey relationships between shorebirds and biofilm are widespread and mediated by multiple ecological and evolutionary determinants. Food source mixing models and energy budget estimates indicate that the strength of the missing linkage is dependent on predator traits (body mass and foraging action rate) and the environment that determines food density. Morphological analyses, showing that smaller bodied species possess more developed feeding apparatus to consume biofilm, suggest that the linkage is also phylogenetically dependent and affords a compelling re-interpretation of niche differentiation. We contend that exploring missing links is a necessity for revealing true network structure and dynamics.

‘Blue Carbon’, which is carbon captured by marine living organisms, has recently been highlighted as a new option for climate change mitigation initiatives. In particular, coastal ecosystems have been recognized as significant carbon stocks because of their high burial rates and long-term sequestration of carbon. However, the direct contribution of Blue Carbon to the uptake of atmospheric CO2 through air-sea gas exchange remains unclear. We performed in situ measurements of carbon flows, including air-sea CO2 fluxes, dissolved inorganic carbon changes, net ecosystem production, and carbon burial rates in the boreal (Furen), temperate (Kurihama), and subtropical (Fukido) seagrass meadows of Japan from 2010 to 2013. In particular, the air-sea CO2 flux was measured using three methods: the bulk formula method, the floating chamber method, and the eddy covariance method. Our empirical results show that submerged autotrophic vegetation in shallow coastal waters can be functionally a sink for atmospheric CO2. This finding is contrary to the conventional perception that most near-shore ecosystems are sources of atmospheric CO2. The key factor determining whether or not coastal ecosystems directly decrease the concentration of atmospheric CO2 may be net ecosystem production. This study thus identifies a new ecosystem function of coastal vegetated systems; they are direct sinks of atmospheric CO2.

High temporal-resolution fluctuations in oxygen concentration and vertical velocity were measured over an intertidal sandflat (water depth < 69 cm) using an oxygen microelectrode and an acoustic Doppler velocimeter, in order to estimate oxygen flux across the sediment -water interface using the eddy-correlation method. The effect of flux estimate procedures, including noise removal and extraction of fluctuating components, was investigated. The estimated oxygen effluxes from the sediment ranged from -3.2 to 6.6 mmol O 2 m -2 h -1 in the light and from -14.5 to -6.6 mmol O 2 m -2 h -1 in the dark. The oxygen-uptake fluxes in the dark were markedly higher than those measured by a conventional enclosure technique. High-frequency turbulence and/or noise (> 5 Hz) observed in the vertical velocity and oxygen concentration data made little contribution to the total oxygen flux (0 to 7%). However, trends (steady change over a longer time scale) caused significant artifacts in the estimated fluxes for several cases. Thus, removal of trends from raw time-series data is recommended. The co-spectrum of the fluctuating components of vertical velocity and oxygen concentration revealed that the oxygen flux at a frequency band between 0.3 and 1.4 Hz (at a period from 0.7 to 3.3 s) was a major contributor to the total oxygen flux. This frequency was consistent with the dominant frequency of vertical velocity, indicating that transport and exchange of porewater and overlying water by wind-induced waves may be crucial processes to dissolved oxygen flux between permeable sandy sediments and shallow waters.

Predators may have a series of alternative foraging modes. Under the food resource maximization hypothesis, predators are expected to shift between foraging modes such that they attain the highest intake rate in response to prey availability and constraints varying with environmental conditions. To test this hypothesis, we measured foraging action rate (actions per unit time), capture rate (captures per unit time), and intake rate (amount of energy and nutrients per unit time) for 2 foraging modes, pecking (feeding on epifauna at the sediment surface) and probing (feeding on infauna by inserting the bill into the sediment), in dunlin Calidris alpina on an intertidal sandflat. The birds chose their foraging mode to attain higher feeding success, i.e. individuals that obtained higher capture and intake rates by pecking allocated a higher proportion of foraging effort to pecking, and vice versa. The birds shifted foraging mode from probing to pecking with increased time after emersion. The shift may be related to decreasing efficiency of probing due to increases in the costs of energy and time caused by decreasing sediment penetrability (increasing hardness) with time after emersion. Our in situ study empirically suggests that, while environmental constraints reduce the predators' foraging mode flexibility, the birds show individual-based appropriate adjustments in their foraging mode to attain a higher intake rate at a given time and patch. This extends the ideal forager model for patch choice into foraging mode choice. KEY WORDS: Decision making · Feeding ecology · Foraging behavior · Intertidal ecosystems · ShorebirdsResale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESS

Among the cyclodepsipeptides, beauveriolides I (1) and II (2) have been isolated from the mycelium of Beauveria sp., and their stereostructures were elucidated by spectral analyses coupled with syntheses of the corresponding 3-hydroxyoctanoic acid derivatives. Beauveriolide I (1) exhibited moderate insecticidal activities against Spodoptera litura and Callosobruchus chinensis.