The swimming abilities of larval fishes are important for their survival, potentially affecting their ability to avoid predators, obtain food and control dispersal patterns. Near settlement swimming ...abilities may also influence spatial and temporal patterns of recruitment. We examined Critical speed (U-crit) swimming ability in late stage larvae of 89 species of coral reef fishes from the Great Barrier Reef and the Caribbean. Coefficients of variation in U-crit calculated at the individual level were high (28.4%), and this was not explained by differences in size or condition factor of these same larvae. Among species U-crit ranged from 5.5 cm s-1 to 100.8 cm s-1 (mean=37.3 cm s-1), with 95% of species able to swim faster than the average current speed around Lizard Island, suggesting that most species should be capable of influencing their spatial and temporal patterns of settlement. Inter-specific differences in swimming ability (at both the family and species levels) were significantly correlated with size and larval morphology. Correlations were found between swimming performance and propulsive area, fineness ratio and aspect ratio, and these morphological parameters may prove useful for predicting swimming ability in other taxa. Overall, the swimming speeds of larvae from the same families at the two locations were relatively similar, although the Lutjanidae and Acanthuridae from the Caribbean were significantly slower than those from the great barrier reef. Differences in swimming speed and body form among late stage larvae suggests that they will respond differently to factors influencing survival and transport during their pelagic phase, as well as habitat use following settlement.
Prerequisites for understanding dispersal in pelagic larvae of demersal fishes are data on when swimming abilities of larvae are sufficiently developed to be able to alter passive dispersal ...trajectories. In laboratory swimming chambers, the development of critical speed and endurance swimming was measured in reared larvae of 4 species of warm-temperate marine and estuarine fishes that spawn pelagic eggs (Sciaenidae,Argyrosomus japonicus; Sparidae,Pagrus auratus,Acanthopagrus australis; Percichthyidae,Macquaria novemaculeata). Size was a better predictor of swimming ability than age. Increase in critical speed with growth was best portrayed by linear or ‘flat’ curvilinear relationships. Increase in endurance was best portrayed by strongly concave curvilinear relationships. The percichthyid larvae had the highest critical speed initially, but speed increased slowly with growth. The 2 sparids had the greatest increase in speed with growth, and the sciaenid the least. The greatest increase in endurance with growth was found inP. auratus, but performance ofM. novemaculeatawas only slightly less. The slowest increase in endurance with growth was found inA. japonicus, but, by settlement, its performance was similar to the other species. Until notochord flexion was complete, both speed and endurance were limited. Thereafter, swimming performance improved markedly at a species-specific rate. At settlement, larvae of these species could swim more than 10 km and at speeds of 15 to 20 cm s–1(=12 to 20 BL s–1), which exceeded the average currents in their coastal environment. Following notochord flexion, all larvae swimming at critical speed were in an inertial environment, and this corresponded to when substantial endurance swimming developed. Whether these potential performances are actually realized in the field remains to be determined, but they provide the potential to strongly influence dispersal.
To address how various environmental parameters control or constrain planktonic respiration (PR), we used geometric scaling relationships and established biological scaling laws to derive ...quantitative predictions for the relationships among key drivers of PR. We then used empirical measurements of PR and environmental (soluble reactive phosphate SRP, carbon DOC, chlorophyll a Chl-a), and temperature) and landscape parameters (lake area LA and watershed area WA) from a set of 44 lakes that varied in size and trophic status to test our hypotheses. We found that landscape-level processes affected PR through direct effects on DOC and temperature and indirectly via SRP. In accordance with predictions made from known relationships and scaling laws, scale coefficients (the parameter that describes the shape of a relationship between 2 variables) were found to be negative and have an absolute value <1. Biological parameters scaled positively with physical and chemical processes in accordance with those predicted from theory or previous studies (i.e., temperature >1, others <1). We also found evidence of a significant relationship between temperature and SRP. Because our dataset included measurements of respiration from small pond catchments to the largest body of freshwater on the planet, Lake Superior, these findings should be applicable to controls of PR for the great majority of temperate aquatic ecosystems.
Behavior of young (8-18 mm SL) giant trevally (Caranx ignobilis), a large coral-reef-associated predator, was observed in the laboratory and the ocean. Size was a better predictor of swimming speed ...and endurance than was age. Critical speed increased with size from 12 to 40 cm/s at 2.7 cm/s for each mm increase in size. Mean scaled critical speed was 19 body lengths/s and was not size related. Swimming speed in the ocean was 4 to 20 cm/s (about half of critical speed) and varied among areas, but within each area, it increased at 2 cm/s for each mm increase in size. Swimming endurance in the laboratory increased from 5 to 40 km at 5 km for each mm increase in size. Vertical distribution changed ontogenetically: larvae swam shallower, but more variably, and then deeper with growth. Two-thirds of individuals swam directionally with no ontogenetic increase in orientation precision. Larvae swam offshore off open coasts, but not in a bay. In situ observations of C. ignobilis feeding, interacting with pelagic animals, and reacting to reefs are reported.
Previous studies of the swimming endurance abilities of late-stage larvae of reef fishes have used laboratory swimming chambers and, with one exception, unfed larvae. Based on the exceptional study, ...we predicted that fed larvae should have much greater endurance than previously reported for unfed larvae. We tested the swimming endurance of the fed late-stage larvae of 6 pomacentrid species and found that all could swim at least twice as long as unfed larvae. The 3 species with larger larvae (12-14mm standard length: SL) all grew during these experiments in spite of being forced to swim 23.3h per day. The 3 species with smaller larvae (10-11mm SL) did not show consistent growth. Unfed laboratory measures of swimming endurance are, therefore, very conservative, and are probably more of an indication of the reserves available to the larvae than a realistic indication of how far the larvae are capable of swimming in the field.PUBLICATION ABSTRACT
The concept of new and regenerated production has been used extensively in marine ecosystems but rarely in freshwaters. We assessed the relative importance of new and regenerated phosphorus (P) in ...sustaining phytoplankton production in Acton Lake, a eutrophic reservoir located in southwestern Ohio, USA. Sources of nutrients to the euphotic zone, including watershed loading, fluxes from sediments, and excretion by sediment-feeding fish (gizzard shad,
Dorosoma cepedianum
), were considered sources of new P input that support new primary production and were quantified over the course of a growing season. Regenerated production was estimated by the difference between new and total primary production. New production represented 32%-53% of total primary production, whereas regenerated production represented 47%-68% of total primary production. P excretion by gizzard shad supplied 45%-74% of new P and 24% of P required for total production. In summary, fluxes of P from the watershed and those from sediment-feeding fish need to be considered in strategies to reduce eutrophication in reservoir ecosystems.
The ICARUS collaboration operated the 760-ton T600 detector in a successful three-year physics run at the underground LNGS laboratories studying neutrino oscillations with the CNGS neutrino beam from ...CERN, and searching for atmospheric neutrino interactions. ICARUS performed a sensitive search for LSND-like anomalous νe appearance in the CNGS beam, which contributed to the constraints on the allowed parameters to a narrow region around $Δm^2=1 e\text{V}^2$, where all the experimental results can be coherently accommodated at 90% C.L. After a significant overhaul at CERN, the T600 detector has been installed at Fermilab. In 2020 cryogenic commissioning began with detector cool down, liquid Argon filling and recirculation. ICARUS has started operations and is presently in its commissioning phase with the aim of collecting its first neutrino events from the Booster Neutrino Beam and the NuMI off-axis beam. The main goal of the first year of ICARUS data taking will then be the definitive verification of the recent claim by NEUTRINO-4 short baseline reactor experiment both in the $ν_μ$ channel with the BNB and in the $ν_e$ with NuMI. After the first year of operations, ICARUS will commence its search for evidence of a sterile neutrino jointly with the SBND near detector, within the Short Baseline Neutrino (SBN) program. The ICARUS exposure to the NuMI beam will also give the possibility for other physics studies such as light dark matter searches and neutrino-Argon cross section measurements. The proposed contribution addresses ICARUS achievements, its status and plans for the new run at Fermilab and the ongoing developments of the analysis tools needed to fulfill its physics program.
Phys. Rev. D 102, 112013 (2020) We present an analysis of MicroBooNE data with a signature of one muon, no
pions, and at least one proton above a momentum threshold of 300 MeV/c
(CC0$\pi$Np). This is ...the first differential cross section measurement of this
topology in neutrino-argon interactions. We achieve a significantly lower
proton momentum threshold than previous carbon and scintillator-based
experiments. Using data collected from a total of approximately $1.6 \times
10^{20}$ protons-on-target, we measure the muon neutrino cross section for the
CC0$\pi$Np interaction channel in argon at MicroBooNE in the Booster Neutrino
Beam which has a mean energy of around 800 MeV. We present the results from a
data sample with estimated efficiency of 29\% and purity of 76\% as
differential cross sections in five reconstructed variables: the muon momentum
and polar angle, the leading proton momentum and polar angle, and the
muon-proton opening angle. We include smearing matrices that can be used to
"forward-fold" theoretical predictions for comparison with these data. We
compare the measured differential cross sections to a number of recent theory
predictions demonstrating largely good agreement with this first-ever data set
on argon.
Phys. Rev. Lett. 125, 201803 (2020) We report on the first measurement of flux-integrated single differential
cross sections for charged-current (CC) muon neutrino ($\nu_\mu$) scattering on
argon ...with a muon and a proton in the final state,
$^{40}$Ar($\nu_\mu$,$\mu$p)X. The measurement was carried out using the Booster
Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE
liquid argon time projection chamber detector with an exposure of 4.59 $\times$
10$^{19}$ protons on target. Events are selected to enhance the contribution of
CC quasielastic (CCQE) interactions. The data are reported in terms of a total
cross section as well as single differential cross sections in final state muon
and proton kinematics. We measure the integrated per-nucleus CCQE-like cross
section (i.e. for interactions leading to a muon, one proton and no pions above
detection threshold) of (4.93 $\pm$ 0.76stat $\pm$ 1.29sys) $\times$
10$^{-38}$cm$^2$, in good agreement with theoretical calculations. The single
differential cross sections are also in overall good agreement with theoretical
predictions, except at very forward muon scattering angles that correspond to
low momentum-transfer events.
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