More Like this

1. Audible changes in marine trophic ecology: Baleen whale song tracks foraging conditions in the eastern North Pacific

   https://doi.org/10.1371/journal.pone.0318624  

   Ryan, John P; Oestreich, William K; Benoit-Bird, Kelly J; Waluk, Chad M; Rueda, Carlos A; Cline, Danelle E; Zhang, Yanwu; Cheeseman, Ted; Calambokidis, John; Fahlbusch, James A; et al (February 2025, PLOS ONE)

   Halliday, William David (Ed.)

   Among tremendous biodiversity within the California Current Ecosystem (CCE) are gigantic mysticetes (baleen whales) that produce structured sequences of sound described as song. From six years of passive acoustic monitoring within the central CCE we measured seasonal and interannual variations in the occurrence of blue (Balaenoptera musculus), fin (Balaenoptera physalus), and humpback (Megaptera novaeangliae) whale song. Song detection during 11 months of the year defines its prevalence in this foraging habitat and its potential use in behavioral ecology research. Large interannual changes in song occurrence within and between species motivates examination of causality. Humpback whales uniquely exhibited continuous interannual increases, rising from 34% to 76% of days over six years, and we examine multiple hypotheses to explain this exceptional trend. Potential influences of physical factors on detectability – including masking and acoustic propagation – were not supported by analysis of wind data or modeling of acoustic transmission loss. Potential influences of changes in local population abundance, site fidelity, or migration timing were supported for two of the interannual increases in song detection, based on extensive local photo ID data (17,356 IDs of 2,407 individuals). Potential influences of changes in foraging ecology and efficiency were supported across all years by analyses of the abundance and composition of forage species. Following detrimental food web impacts of a major marine heatwave that peaked during the first year of the study, foraging conditions consistently improved for humpback whales in the context of their exceptional prey-switching capacity. Stable isotope data from humpback and blue whale biopsy samples are consistent with observed interannual variations in the regional abundance and composition of forage species. This study thus indicates that major interannual changes in detection of baleen whale song may reflect underlying variations in forage species availability driven by energetic variations in ecosystem state. 

   more » « less
2. Soundscape enrichment increases larval settlement rates for the brooding coral Porites astreoides

   https://doi.org/10.1098/rsos.231514  

   Aoki, Nadège; Weiss, Benjamin; Jézéquel, Youenn; Zhang, Weifeng Gordon; Apprill, Amy; Mooney, T Aran (March 2024, Royal Society Open Science)

   The_Royal_Society_Publishing (Ed.)

   Coral reefs, hubs of global biodiversity, are among the world’s most imperilled habitats. Healthy coral reefs are characterized by distinctive soundscapes; these environments are rich with sounds produced by fishes and marine invertebrates. Emerging evidence suggests these sounds can be used as orientation and settlement cues for larvae of reef animals. On degraded reefs, these cues may be reduced or absent, impeding the success of larval settlement, which is an essential process for the maintenance and replenishment of reef populations. Here, in a field-based study, we evaluated the effects of enriching the soundscape of a degraded coral reef to increase coral settlement rates.Porites astreoideslarvae were exposed to reef sounds using a custom solar-powered acoustic playback system.Porites astreoidessettled at significantly higher rates at the acoustically enriched sites, averaging 1.7 times (up to maximum of seven times) more settlement compared with control reef sites without acoustic enrichment. Settlement rates decreased with distance from the speaker but remained higher than control levels at least 30 m from the sound source. These results reveal that acoustic enrichment can facilitate coral larval settlement at reasonable distances, offering a promising new method for scientists, managers and restoration practitioners to rebuild coral reefs. 

   more » « less
3. Waterline responses to climate forcing along the North American West Coast

   https://doi.org/10.1038/s43247-025-02414-x  

   Graffin, Marcan; Almar, Rafael; Bergsma, Erwin_W J; Boucharel, Julien; Vitousek, Sean; Taherkhani, Mohsen; Ruggiero, Peter (December 2025, Communications Earth & Environment)

   Understanding waterline variability at seasonal to interannual timescales is crucial for predicting coastal responses to climate forcing. However, relationships between large-scale climate variability and coastal morphodynamics remain underexplored beyond intensively monitored sites. This study leverages a newly developed 25-year (1997–2022) satellite-derived waterline dataset along the North American West Coast. Our results reveal distinct latitudinal patterns in seasonal waterline change, with excursions exceeding 25 m in the Pacific Northwest, decreasing to less than 10 m in Southern California and farther south. Waterline fluctuations strongly follow wave power in the Pacific Northwest (R = −0.78), northern California (R = −0.75), and Baja California (R = −0.62), while Baja California Sur aligns more with sea-level variations (R = −0.42). Interannually, waterline change exhibits latitudinal dependence: south of southern California, variability is low, with major erosion confined to strong El Niño-Southern Oscillation (ENSO) events, while northern regions show mixed responses. ENSO-driven storm track shifts modulate winter wave climate, resulting in enhanced (attenuated) erosion from southern California to Baja California Sur during El Niño (La Niña). However, further north, ENSO impacts are less consistent, reflecting a complex interplay of storm track displacement and intensification. These findings highlight the spatial complexity of ENSO-driven morphodynamics and provide a framework for assessing climate-induced coastal vulnerability. 

   more » « less
4. TRACKING DEEP-WATER OXYGENATION CHANGES OFFSHORE SOUTHERN CALIFORNIA

   Duff, E.; Troxel, A.; Haygood, L.; Ford, T.; Burkett, A.; Reidinger, N. (March 2023, Geological Society of America South-Central Section)

   none. (Ed.)

   Upwelling systems on eastern boundaries of subtropical ocean basins are some of the most climatically dynamic regions of the oceans. Anthropogenic climate change has implications for these marine ecosystems, such as driving marine deoxygenation, driving ecosystem zonation, and driving the expansion of oxygen minimum zones (OMZ). There have been multiple studies evaluating drivers of marine oxygenation changes, yet there is still a need to understand surface processes and source waters influence on bottom-water oxygenation. The California continental margin is a well-studied upwelling system, where source water mixing of oxygen-rich subarctic waters to oxygen-poor subtropical waters is strongly influenced by the California Current, leading to one of the most primary production areas in the Pacific. Here we present data of redox sensitive trace metals to evaluate changes in the bottom water ventilation off the coast of Southern California due to climatic changes. Samples from several sediment cores were recovered via the RV Roger Revelle Expedition RV2206 during the summer of 2022. The sediment samples were digested applying a multi-acid digestion technique and analyzing together with pore water samples via inductively coupled plasma mass spectrometry. Interestingly, we observe a strong flux of specific heavy metals from the sediments into the overlying water column, likely impacting the benthic community and altering the primary metal-proxy signal at these sites with potential implications for the reconstruction of current ventilation through these geochemical and microfossil tracers. Overall, our preliminary results indicate fluctuations in the OMZ seaward expansion with implications for the oxygenation condition of the deeper water. 

   more » « less
5. Trends in Nitrate, Ammonium, and Total Nitrogen Deposition in the Lake Erie Basin: A 20-Year Analysis

   Ruano, D; Astitha, M (November 2024, National Atmospheric Deposition Program)

   This study examines changes in nitrogen deposition in the Lake Erie basin since 2000, focusing on five monitoring sites of the National Atmospheric Deposition Program (NADP): Chautauqua (NY10) and Kane Experimental Forest (PA29) in the east, Wooster (OH71) and Roush Lake (IN20) in the west, and Kellogg Biological Station (MI26) in the northwest. Quantitative analysis revealed consistent decrease in nitrate (NO3-) levels across all monitoring sites. The average reduction in nitrate deposition was 33% over the study period, with western sites showing slightly higher reductions compared to the eastern sites. Specifically, the western sites of Wooster (OH71) and Roush (IN20) exhibited decreases of 37% and 35%, respectively, while eastern sites of Chautauqua (NY10) and Kane (PA29) showed reductions of 30% and 31%. Ammonium (NH4+) levels, in contrast, showed cyclic fluctuations with peaks occurring approximately every 7-10 years over the study period. At Kane (PA29), ammonium levels fluctuated by ±15% around the mean value. Wooster (OH71) showed similar fluctuations of ±13%, while Kellogg (MI26) exhibited the highest variability at ±18%. Total nitrogen deposition, combining both nitrate and ammonium, followed a decreasing trend similar to nitrate. The average reduction in total nitrogen deposition was approximately 30% across the monitoring sites. Chautauqua (NY10) exhibited a 28% reduction, Kane (PA29) 29%, Wooster (OH71) 33%, Roush (IN20) 32%, and Kellogg (MI26) 32%. Spatial analysis evidenced regional differences in nitrogen deposition trends. The western sites (OH71, IN20) showed higher reductions in nitrate deposition (36% on average) compared to the eastern sites (NY10, PA29) (30.5% on average). This east-west disparity may be due to differences in local emission sources, prevailing wind patterns, or variations in the implementation of nitrogen reduction measures. The northwestern site, MI26, showed nitrate reductions (32%) intermediate between western and eastern sites, suggesting a potential gradient in deposition changes across the Lake Erie basin. Observed reductions in nitrogen deposition, particularly nitrate, suggest the effectiveness of regulatory measures aimed at reducing nitrogen oxide emissions. However, persistent cyclic fluctuations in ammonium deposition highlight the need for continued monitoring and management of agricultural nutrient runoff. These findings have significant ecological implications for Lake Erie, potentially helping to mitigate eutrophication and reduce frequency and intensity of harmful algal blooms. The study underscores the importance of NADP's comprehensive, long-term monitoring. These valuable insights could inform adaptive management strategies for the Lake Erie basin, balancing economic activities with ecosystem health in the face of ongoing climate change and land-use pressures. 

   more » « less