Acoustic and biological trends on coral reefs off Maui, Hawaii

Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Coral Reefs 37 (2018): 121-133, doi:10.1007/s00338-017-1638-x.Coral reefs are characterized by high biodiversity and evidence suggests that reef soundscapes reflect local species assemblages. To investigate how sounds produced on a given reef relate to abiotic and biotic parameters and how that relationship may change over time, an observational study was conducted between September 2014 and January 2016 at seven Hawaiian reefs that varied in coral cover, rugosity, and fish assemblages. The reefs were equipped with temperature loggers and acoustic recording devices that recorded on a 10% duty cycle. Benthic and fish visual survey data were collected four times over the course of the study. On average, reefs ranged from 0 to 80% live coral cover, although changes between surveys were noted, in particular during the major El Niño-related bleaching event of October 2015. Acoustic analyses focused on two frequency bands (50–1200 Hz and 1.8–20.5 kHz) that corresponded to the dominant spectral features of the major sound-producing taxa on these reefs, fish and snapping shrimp, respectively. In the low-frequency band, the presence of humpback whales (December– May) was a major contributor to sound level, whereas in the high-frequency band sound level closely tracked water temperature. On shorter timescales, the magnitude of the diel trend in sound production was greater than that of the lunar trend, but both varied in strength among reefs, which may reflect differences in the species assemblages present. Results indicated that the magnitude of the diel trend was related to fish densities at low frequencies and coral cover at high frequencies; however, the strength of these relationships varied by season. Thus, long-term acoustic recordings capture the substantial acoustic variability present in coral-reef ecosystems and provide insight into the presence and relative abundance of sound-producing organisms.Funding for this research was provided by the PADI Foundation, the WHOI Access To The Sea initiative and Ocean Life Institute, and the National Science Foundation grant OCE-1536782

Fluctuations in Hawaii's humpback whale Megaptera novaeangliae population inferred from male song chorusing off Maui

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Kugler, A., Lammers, M. O., Zang, E. J., Kaplan, M. B., & Mooney, T. A. Fluctuations in Hawaii's humpback whale Megaptera novaeangliae population inferred from male song chorusing off Maui. Endangered Species Research, 43, (2020): 421-434, https://doi.org/10.3354/esr01080.Approximately half of the North Pacific humpback whale Megaptera novaeangliae stock visits the shallow waters of the main Hawaiian Islands seasonally. Within this breeding area, mature males produce an elaborate acoustic display known as song, which becomes the dominant source of ambient underwater sound between December and April. Following reports of unusually low whale numbers that began in 2015/16, we examined song chorusing recorded through long-term passive acoustic monitoring at 6 sites off Maui as a proxy for relative whale abundance between 2014 and 2019. Daily root-mean-square sound pressure levels (RMS SPLs) were calculated to compare variations in low-frequency acoustic energy (0-1.5 kHz). After 2014/15, the overall RMS SPLs decreased between 5.6 and 9.7 dB re 1 µPa2 during the peak of whale season (February and March), reducing ambient acoustic energy from chorusing by over 50%. This change in song levels co-occurred with a broad-scale oceanic heat wave in the northeast Pacific termed the ‘Blob,’ a major El Niño event in the North Pacific, and a warming period in the Pacific Decadal Oscillation cycle. Although it remains unclear whether our observations reflect a decrease in population size, a change in migration patterns, a shift in distribution to other areas, a change in the behavior of males, or some combination of these, our results indicate that continued monitoring and further studies of humpback whales throughout the North Pacific are warranted to better understand the fluctuations occurring in this recently recovered population and other populations that continue to be endangered or threatened.Funding was provided by The WHOI Access To The Sea initiative and Ocean Life Institute,National Science Foundation grant OCE-1536782, Department of Land and Natural Resources of the State of Hawai’i, Whale Tales Maui, Pride of Maui, the PADI Foundation, and the National Marine Sanctuary Foundation

Influence of bottom topography on integral constraints in zonal flows with parameterized potential vorticity fluxes

An integral constraint for eddy fluxes of potential vorticity (PV), corresponding to global momentum conservation, is applied to two-layer zonal quasi-geostrophic channel flow. This constraint must be satisfied for any type of parameterization of eddy PV fluxes. Bottom topography strongly influence the integral constraint compared to a flat bottom channel. An analytical solution for the mean flow solution has been found by using asymptotic expansion in a small parameter which is the ratio of the Rossby radius to the meridional extent of the channel. Applying the integral constraint to this solution, one can find restrictions for eddy PV transfer coefficients which relate the eddy fluxes of PV to the mean flow. These restrictions strongly deviate from restrictions for the channel with flat bottom topography

Correlation Functions of Conserved Currents in N = 2 Superconformal Theory

Using a manifestly supersymmetric formalism, we determine the general structure of two- and three- point functions of the supercurrent and the flavour current of N = 2 superconformal field theories. We also express them in terms of N = 1 superfields and compare to the generic N = 1 correlation functions. A general discussion of the N = 2 supercurrent superfield and the multiplet of anomalies and their definition as derivatives with respect to the supergravity prepotentials is also included.Comment: 43 pages, latex, no figures, v.2: section 4.2 extende

Gauge-invariant correlation functions in light-cone superspace

We initiate a study of correlation functions of gauge-invariant operators in N=4 super Yang-Mills theory using the light-cone superspace formalism. Our primary aim is to develop efficient methods to compute perturbative corrections to correlation functions. This analysis also allows us to examine potential subtleties which may arise when calculating off-shell quantities in light-cone gauge. We comment on the intriguing possibility that the manifest N=4 supersymmetry in this approach may allow for a compact description of entire multiplets and their correlation functions.Comment: 35 pages, several figure

Localization of shadow poles by complex scaling

Through numerical examples we show that the complex scaling method is suited to explore the pole structure in multichannel scattering problems. All poles lying on the multisheeted Riemann energy surface, including shadow poles, can be revealed and the Riemann sheets on which they reside can be identified.Comment: 6 pages, Latex with Revtex, 3 figures (not included) available on reques

Renormalization group flow with unstable particles

The renormalization group flow of an integrable two dimensional quantum field theory which contains unstable particles is investigated. The analysis is carried out for the Virasoro central charge and the conformal dimensions as a function of the renormalization group flow parameter. This allows to identify the corresponding conformal field theories together with their operator content when the unstable particles vanish from the particle spectrum. The specific model considered is the $SU(3)_{2}$-homogeneous Sine-Gordon model.Comment: 5 pages Latex, 3 figure

Range expansion with mutation and selection: dynamical phase transition in a two-species Eden model

The colonization of unoccupied territory by invading species, known as range expansion, is a spatially heterogeneous non-equilibrium growth process. We introduce a two-species Eden growth model to analyze the interplay between uni-directional (irreversible) mutations and selection at the expanding front. While the evolutionary dynamics leads to coalescence of both wild-type and mutant clusters, the non-homogeneous advance of the colony results in a rough front. We show that roughening and domain dynamics are strongly coupled, resulting in qualitatively altered bulk and front properties. For beneficial mutations the front is quickly taken over by mutants and growth proceeds Eden-like. In contrast, if mutants grow slower than wild-types, there is an antagonism between selection pressure against mutants and growth by the merging of mutant domains with an ensuing absorbing state phase transition to an all-mutant front. We find that surface roughening has a marked effect on the critical properties of the absorbing state phase transition. While reference models, which keep the expanding front flat, exhibit directed percolation critical behavior, the exponents of the two-species Eden model strongly deviate from it. In turn, the mutation-selection process induces an increased surface roughness with exponents distinct from that of the classical Eden model

Two-loop Integrability of Planar N=6 Superconformal Chern-Simons Theory

Bethe ansatz equations have been proposed for the asymptotic spectral problem of AdS_4/CFT_3. This proposal assumes integrability, but the previous verification of weak-coupling integrability covered only the su(4) sector of the ABJM gauge theory. Here we derive the complete planar two-loop dilatation generator of N=6 superconformal Chern-Simons theory from osp(6|4) superconformal symmetry. For the osp(4|2) sector, we prove integrability through a Yangian construction. We argue that integrability extends to the full planar two-loop dilatation generator, confirming the applicability of the Bethe equations at weak coupling. Further confirmation follows from an analytic computation of the two-loop twist-one spectrum.Comment: 45 pages, v2: typos in (D.9) fixed, reference added, many small change