Effect of wind and tidal advection on distribution patterns of rock crab \u3cem\u3eCancer irroratus\u3c/em\u3e megalopae in Block Island Sound, Rhode Island

The planktonic period of benthic marine invertebrates can significantly affect distribution patterns of benthic juveniles. In this paper we address the relationship between advection and the subsequent abundance of planktonic megalopae of the rock crab Cancer irroratus in Block Island Sound, Rhode Island (USA), over an 8 yr period. At small scales (several meters distance with samples taken simultaneously), megalopae were found to be similarly distributed; at larger temporal (tens of minutes) and spatial scales (hundreds of meters) megalopae were very patchy, which indicates a complex, highly variable pattern of abundance typical of planktonic systems. Using the receptor-mode trajectory capability of OILMAP, a numerical hydrodynamic model, we detected a significant relationship between the direction of transport prior to collection (as predicted by the model) and the subsequent catch of megalopae. We argue that rock crab megalopae are often advected tens of kilometers over short time spans and are concentrated on south-facing shores in Block Island Sound. Further, enhanced planktonic delivery to our study area results in large pulses of individuals to the benthos. Directional transport would be an effective larval delivery strategy even if rock crab megalopae were subject to lower advection, perhaps owing to a deep vertical distribution; a significant relationship between transport direction and collection date was detected even under a lower advective regime

Natural diet and feeding habits of the postlarval lobster Homarus americanus

Postlarval Homarus arnericanus were collected from Block Island Sound, Rhode Island, USA, during 5 diel neuston sampling periods in summer 1988 and 1989. The foregut contents of the postlarvae were determined and compared with the relative abundances of potential prey groups in the plankton. Nine taxonomic prey groups were identified in the gut contents (N = 802). The composition of the prey groups and their relative frequencies of occurrence in the guts did not differ with time of day or sampling period. The frequent occurrence of copepods, decapod larvae, fish eggs and insect parts indicates a predominantly carnivorous feeding habit. Furthermore, the disproportionate frequency of occurrence of large copepod species and decapod larvae in the guts relative to their densities in the plankton suggests a preference for larger sized prey. Contrary to expectations, the mean gut fullness and condition of gut contents of individuals at different molt stages were not significantly different. Likewise, there was no significant difference in the incidence of guts with newly ingested prey between postlarvae in the premolt stages and those in the post and intermolt stages. Completely empty guts were rare. In addition, the variability in gut fullness and the condition of gut contents among individuals was high during all sampling periods. These indicate that postlarvae in the field forage successfully throughout the day. However, the significantly higher incidence of newly ingested prey in the guts of postlarval lobsters at night indicates a higher feeding activity during this time

Growth rates of planktonic and newly settled American lobsters \u3cem\u3eHomarusamericanus\u3c/em\u3e

Growth rates, as estimated by the RNA:DNA ratio, were determined for planktonic postlarvae and for recaptured and wild newly settled benthic stages (fifth and sixth instars) of the American lobster Homarus americanus. The mean growth rate of planktonic postlarvae in 1994 was 0.522 ± 0.247 mg protein d-1. This was significantly higher than planktonic growth rates observed in 1991 (0.449 ± 0.121 mg protein d-1) but not in 1992 (0.460 ± 0.144 mg protein d-1). The percentage of poorly nourished planktonic postlarvae, those with growth rates \u3c0.220 mg protein d-1, ranged from 3 to 13% in 1991, 1992 and 1994 and was similar to that observed in previous years (1988 to 1990). Newly settled lobsters had significantly lower mean growth rates (0.223 ± 0.180 mg protein d-1) than planktonic postlarvae. Recaptured lobsters originating from wild stock had significantly higher growth rates than those originating from laboratory stock (0.281 ± 0.176 vs 0.085 ± 0.078 mg protein d-1, respectively). Laboratory rearing effects (lowered growth rates) appeared to persist even after 1 wk in the field. The differences in the growth rates between planktonic and benthic phase lobsters may be evidence of a trade-off between slow growth due to decreased food ingestion and potential increased vulnerability to predation when actively foraging

Influence of size and delayed settlement on the recapture rate of newly settled American lobsters \u3cem\u3eHomarus americanus\u3c/em\u3e

Postlarval American lobsters Homarus americanus exhibit variation in size at settlement and timing of settlement but it is not known if this variability influences future survival. The ability to track the fate of individual newly settled lobsters has become possible with the advent of micro-wire tags. In this study micro-wire tags were used to identify individual postlarval and fifth instar lobsters that were released into the field and then recaptured 1 wk later. The influence of size at settlement and timing of settlement on subsequent recapture rate were determined. The overall recapture rate for tagged postlarvae and fifth instars was approximately 15%. Larger sized postlarvae and fifth instar lobsters were recaptured significantly more frequently than their smaller counterparts. There was no difference in recapture rate for postlarvae that delayed settlement, as compared to those that settled at the normal time. Differences in recapture rates between large- and small-sized newly settled lobsters might be associated with emigration, behavioral interactions, or differential survival

Behavioral Analysis of the Escape Response in the Juvenile Lobster Homarus Americanus Over the Molt Cycle

1. Components of the escape response of the American lobster were compared over the molt cycle. Number of tailflips, frequency, duration and distance were measured. Velocity, acceleration, force and work were computed from the above measurements, using time-lapse video-recordings of escaping lobsters. 2. Soft-shelled postmolt lobsters (stage B) traveled further, spent more time tailflipping and performed a larger number of tailflips than hard-shelled premolt lobsters (stage D). Hard-shelled lobsters had a more forceful initial power swim, achieved a higher overall velocity and acceleration and, therefore, produced more forceful swims with greater energy expenditure (measured by work output) than soft-shelled animals. 3. Among hard-shelled lobsters, velocity, acceleration, force and work fell off markedly in the latter part of their subsequent swims as a consequence of the prolonged duration and reduced frequency of these swims. Soft-shelled lobsters sustained their swimming velocity, acceleration, force and work for their entire subsequent swimming response. 4. There are likely to be large molt-related differences in energy metabolism, endocrinology and nerve and muscle physiology which lead to the observed differences in the escape response

Coastal Lagoons and Climate Change: Ecological and Social Ramifications in the U.S. Atlantic and Gulf Coast Ecosystems

Lagoons are highly productive coastal features that provide a range of natural services that society values. Their setting within the coastal landscape leaves them especially vulnerable to profound physical, ecological, and associated societal disturbance from global climate change. Expected shifts in physical and ecological characteristics range from changes in flushing regime, freshwater inputs, and water chemistry to complete inundation and loss and the concomitant loss of natural and human communities. Therefore, managing coastal lagoons in the context of global climate change is critical. Although management approaches will vary depending on local conditions and cultural norms, all management scenarios will need to be nimble and to make full use of the spectrum of values through which society views these unique ecosystems. We propose that this spectrum includes pragmatic, scholarly, aesthetic, and tacit categories of value. Pragmatic values such as fishery or tourism revenue are most easily quantified and are therefore more likely to be considered in management strategies. In contrast, tacit values such as a sense of place are more difficult to quantify and therefore more likely to be left out of explicit management justifications. However, tacit values are the most influential to stakeholder involvement because they both derive from and shape individual experiences and beliefs. Tacit values underpin all categories of social values that we describe and can be expected to have a strong influence over human behavior. The articulation and inclusion of the full spectrum of values, especially tacit values, will facilitate and support nimble adaptive management of coastal lagoon ecosystems in the context of global climate change

Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.2–2.3 π mm-rad horizontally and 0.6–1.0 π mm-rad vertically, a horizontal dispersion of 90–190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE

Immunomodulation of murine collagen-induced arthritis by N, N-dimethylglycine and a preparation of Perna canaliculus

<p>Abstract</p> <p>Background</p> <p>Rheumatoid arthritis (RA) and its accepted animal model, murine collagen-induced arthritis (CIA), are classic autoimmune inflammatory diseases which require proinflammatory cytokine production for pathogenesis. We and others have previously used N, N-dimethylglycine (DMG) and extracts from the New Zealand green-lipped mussel <it>Perna canaliculus </it>(Perna) as potent immunomodulators to modify ongoing immune and/or inflammatory responses.</p> <p>Methods</p> <p>In our initial studies, we treated lipopolysaccahride (LPS) stimulated THP-1 monocytes <it>in vitro </it>with increasing concentrations of Perna extract or DMG. Additionally, we treated rat peripheral blood neutrophils with increasing concentrations of Perna extract and measured superoxide burst. In subsequent <it>in vivo </it>experiments, CIA was induced by administration of type II collagen; rats were prophylactically treated with either Perna or DMG, and then followed for disease severity. Finally, to test whether Perna and/or DMG could block or inhibit an ongoing pathologic disease process, we induced CIA in mice and treated them therapeutically with either of the two immunomodulators.</p> <p>Results</p> <p>Following LPS stimulation of THP-1 monocytes, we observed dose-dependent reductions in TNF-α and IL-12p40 production in Perna treated cultures. DMG treatment, however, showed significant increases in both of these cytokines in the range of 0.001–1 μM. We also demonstrate that <it>in vitro </it>neutrophil superoxide burst activity is dose-dependently reduced in the presence of Perna. Significant reductions in disease incidence, onset, and severity of CIA in rats were noted following prophylactic treatment with either of the two immunomodulators. More importantly, amelioration of mouse CIA was observed following therapeutic administration of Perna. In contrast, DMG appeared to have little effect in mice and may act in a species-specific manner.</p> <p>Conclusion</p> <p>These data suggest that Perna, and perhaps DMG, may be useful supplements to the treatment of RA in humans.</p

First demonstration of ionization cooling by the Muon Ionization Cooling Experiment

High-brightness muon beams of energy comparable to those produced by state-of-the-art electron, proton and ion accelerators have yet to be realised. Such beams have the potential to carry the search for new phenomena in lepton-antilepton collisions to extremely high energy and also to provide uniquely well-characterised neutrino beams. A muon beam may be created through the decay of pions produced in the interaction of a proton beam with a target. To produce a high-brightness beam from such a source requires that the phase space volume occupied by the muons be reduced (cooled). Ionization cooling is the novel technique by which it is proposed to cool the beam. The Muon Ionization Cooling Experiment collaboration has constructed a section of an ionization cooling cell and used it to provide the first demonstration of ionization cooling. We present these ground-breaking measurements.Comment: 19 pages and 6 figure

Demonstration of cooling by the Muon Ionization Cooling Experiment

The use of accelerated beams of electrons, protons or ions has furthered the development of nearly every scientific discipline. However, high-energy muon beams of equivalent quality have not yet been delivered. Muon beams can be created through the decay of pions produced by the interaction of a proton beam with a target. Such ‘tertiary’ beams have much lower brightness than those created by accelerating electrons, protons or ions. High-brightness muon beams comparable to those produced by state-of-the-art electron, proton and ion accelerators could facilitate the study of lepton–antilepton collisions at extremely high energies and provide well characterized neutrino beams1,2,3,4,5,6. Such muon beams could be realized using ionization cooling, which has been proposed to increase muon-beam brightness7,8. Here we report the realization of ionization cooling, which was confirmed by the observation of an increased number of low-amplitude muons after passage of the muon beam through an absorber, as well as an increase in the corresponding phase-space density. The simulated performance of the ionization cooling system is consistent with the measured data, validating designs of the ionization cooling channel in which the cooling process is repeated to produce a substantial cooling effect9,10,11. The results presented here are an important step towards achieving the muon-beam quality required to search for phenomena at energy scales beyond the reach of the Large Hadron Collider at a facility of equivalent or reduced footprint6