Biology

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WHOI biological oceanographers study the biology of individual marine organisms, their spatial and temporal distributions, and how they interact both with their surrounding environment and with each other.

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Now showing 1 - 20 of 1808
  • Article
    Applying environmental DNA approaches to inform marine biodiversity conservation: the case of the Ocean Twilight Zone
    (Elsevier, 2024-05-06) Yang, Nina ; Jin, Di ; Govindarajan, Annette F.
    Effective governance of the global ocean under accelerating environmental and social changes depends on sufficient scientific knowledge that unravels the complexity of dynamic marine ecosystems. In the case of the vast and remote ocean twilight zone (OTZ), management is particularly challenged by the lack of data. Traditional biodiversity monitoring methods are unable to scale efficiently or effectively to address these knowledge gaps and new technologies are needed to inform policy. Environmental DNA (eDNA) has quickly gained traction in recent years as an enabling technology for marine conservation that will play a transformative role in OTZ biodiversity conservation and high seas governance in general. Through a comprehensive review of science and policy literature and an analysis of existing global marine biodiversity data, we discuss the importance of biodiversity conservation in the OTZ, review existing knowledge gaps, and summarize recent developments in eDNA and OTZ biodiversity research. We identify the key components of an eDNA framework that are needed for OTZ biodiversity monitoring and discuss policy implications relevant to the recent Biodiversity Beyond National Jurisdiction (BBNJ) Agreement. We show that an integrated science-policy approach based on transdisciplinary eDNA research is essential for achieving sustainability in the OTZ and the 30×30 target for conserving ocean biodiversity.
  • Article
    Wallace’s line structures seagrass microbiota and is a potential barrier to the dispersal of marine bacteria
    (Springer Nature, 2024-04-18) Wainwright, Benjamin J. ; Leon, Josh ; Vilela, Ernie ; Hickman, Jo ; Caldwell, Jensen ; Aimone, Behlee ; Bischoff, Porter ; Ohran, Marissa ; Morelli, Magnolia W. ; Arlyza, Irma S. ; Marwayana, Onny N. ; Zahn, Geoffrey
    The processes that shape microbial biogeography are not well understood, and concepts that apply to macroorganisms, like dispersal barriers, may not affect microorganisms in the same predictable ways. To better understand how known macro-scale biogeographic processes can be applied at micro-scales, we examined seagrass associated microbiota on either side of Wallace’s line to determine the influence of this cryptic dispersal boundary on the community structure of microorganisms. Communities were examined from twelve locations throughout Indonesia on either side of this theoretical line. We found significant differences in microbial community structure on either side of this boundary (R2 = 0.09; P = 0.001), and identified seven microbial genera as differentially abundant on either side of the line, six of these were more abundant in the West, with the other more strongly associated with the East. Genera found to be differentially abundant had significantly smaller minimum cell dimensions (GLM: t923 = 59.50, P < 0.001) than the overall community. Despite the assumed excellent dispersal ability of microbes, we were able to detect significant differences in community structure on either side of this cryptic biogeographic boundary. Samples from the two closest islands on opposite sides of the line, Bali and Komodo, were more different from each other than either was to its most distant island on the same side. We suggest that limited dispersal across this barrier coupled with habitat differences are primarily responsible for the patterns observed. The cryptic processes that drive macroorganism community divergence across this region may also play a role in the bigeographic patterns of microbiota.
  • Article
    Distinct responses to warming within picoplankton communities across an environmental gradient
    (Wiley, 2024-05-20) Stevens, Bethany L. F. ; Peacock, Emily E. ; Crockford, E. Taylor ; Shalapyonok, Alexi ; Neubert, Michael G. ; Sosik, Heidi M.
    Picophytoplankton are a ubiquitous component of marine plankton communities and are expected to be favored by global increases in seawater temperature and stratification associated with climate change. Eukaryotic and prokaryotic picophytoplankton have distinct ecology, and global models predict that the two groups will respond differently to future climate scenarios. At a nearshore observatory on the Northeast US Shelf, however, decades of year-round monitoring have shown these two groups to be highly synchronized in their responses to environmental variability. To reconcile the differences between regional and global predictions for picophytoplankton dynamics, we here investigate the picophytoplankton community across the continental shelf gradient from the nearshore observatory to the continental slope. We analyze flow cytometry data from 22 research cruises, comparing the response of picoeukaryote and Synechococcus communities to environmental variability across time and space. We find that the mechanisms controlling picophytoplankton abundance differ across taxa, season, and distance from shore. Like the prokaryote, Synechococcus, picoeukaryote division rates are limited nearshore by low temperatures in winter and spring, and higher temperatures offshore lead to an earlier spring bloom. Unlike Synechococcus, picoeukaryote concentration in summer decreases dramatically in offshore surface waters and exhibits deeper subsurface maxima. The offshore picoeukaryote community appears to be nutrient limited in the summer and subject to much greater loss rates than Synechococcus. This work both produces and demonstrates the necessity of taxon- and site-specific knowledge for accurately predicting the responses of picophytoplankton to ongoing environmental change.
  • Article
    Quebec legislative framework for the protection of wild species in precarious situations: Critical evaluation and recommendations for a major revision
    (Canadian Science Publishing, 2024-04-30) Pelletier, Fanie ; Dumont, Pierre ; Van de Walle, Joanie ; Jauvin, Daniel ; Rodrigue, David
    In Quebec, the Act Respecting Threatened or Vulnerable species (ARTV), adopted in 1989, aims to safeguard Quebec's wild genetic diversity by protecting species at risk. However, since its implementation about 30 years ago, it has been repeatedly pointed out that the application of the Quebec legislative framework for the protection of wildlife species at risk was often slow and inadequate. The aim of this article is therefore to make a series of observations on the limits of current legislation and then propose nine urgent recommendations to improve the effectiveness of conservation efforts for species at risk in Quebec. Our recommendations aim to increase the efficiency and transparency of the designation process, reconsider compensation mechanisms for the loss of critical habitat, and harmonize species status between the federal and provincial levels. We hope that our article will pave the way for a constructive discussion leading to an improved protection of wildlife species in precarious situations and their persistence for future generations. The English version of this article is available in the Supplementary material file.
  • Article
    Faunal colonists, including mussel settlers, respond to microbial biofilms at deep-sea hydrothermal vents
    (Elsevier, 2024-04-29) Ladd, Tanika M. ; Selci, Matteo ; Davis, Dexter J. ; Cannon, Olivia ; Plowman, Caitlin Q. ; Schlegel, Ian ; Inaba, Aila ; Mills, Susan Wier ; Vetriani, Costantino ; Mullineaux, Lauren S. ; Arellano, Shawn M.
    Colonization processes at dynamic deep-sea hydrothermal vent ecosystems ultimately determine ecosystem structure, function, resilience, and recovery. Microbial biofilms form rapidly on surfaces near hydrothermal vents and are continuously exposed to the highly variable abiotic environment. Thus, biofilm microbes may provide a temporally integrated signal that can indicate whether the habitat is suitable for faunal colonists. This study explored the role of microbial biofilms in controlling faunal colonization through in-situ colonization experiments at Tica Vent in the 9°50’ N region of the East Pacific Rise (EPR). Short-term experiments (∼2 weeks) were conducted by deploying colonization surfaces (“sandwiches”) either with an established biofilm (developed for >1 year) or a fresh biofilm (developed throughout experiment) in zones characterized by different faunal assemblages. Differences in associated larval settlers, faunal immigrants, and microbial communities according to biofilm age across multiple biogenic zones were investigated. Faunal and microbial community compositions significantly differed according to whether the sandwiches had established or fresh biofilms as well as the biogenic zone they were deployed in. Several faunal colonists, including settlers such as the foundational chemosymbiotic mussel Bathymodiolus thermophilus and the nectochaete Archinome sp., were found associated more with established biofilms than fresh biofilms. Microbial biofilm communities were dominated by putative chemoautotrophic members of the Campylobacterota phylum and Gammaproteobacteria class and several microbial taxa were found to covary with faunal colonists. Overall, these findings show that microbial community composition plays a role in larval settlement and animal migration in hydrothermal vent systems and the detection of microbial and faunal interactions provides a starting point for identifying key microbial characteristics influencing colonization processes at hydrothermal vents.
  • Article
    Comparative analysis of the molecular starvation response of Southern Ocean copepods
    (Wiley, 2024-05-09) Berger, Cory A. ; Steinberg, Deborah K. ; Copeman, Louise A. ; Tarrant, Ann M.
    Large lipid-storing copepods dominate mesozooplankton biomass in the polar oceans and form a critical link between primary production and higher trophic levels. The ecological success of these species depends on their ability to survive periods of food deprivation in a highly seasonal environment, but the molecular changes that mediate starvation tolerance in these taxa are unknown. We conducted starvation experiments for two dominant Southern Ocean copepods, Calanoides acutus and Calanus propinquus, allowing us to compare the molecular starvation response between species. These species differ in life history, diet and metabolic traits, and expressed overlapping but distinct transcriptomic responses to starvation. Most starvation-response genes were species-specific, but we identified a conserved core set of starvation-response genes related to RNA and protein metabolism. We used phylotranscriptomics to place these results in the context of copepod evolution and found that starvation-response genes are under strong purifying selection at the sequence level and stabilizing selection at the expression level, consistent with their role in mediating essential biological functions. Selection on starvation-response genes was especially strong in our focal lipid-storing lineage relative to other copepod taxa, underscoring the significance of starvation tolerance for these species. We also found that certain key lipid enzymes (elongases and desaturases) have experienced diversification and positive selection in lipid-storing lineages, reflecting the unique lipid storage needs of these animals. Our results shed light on the molecular adaptations of high-latitude zooplankton to variable food conditions and suggest that starvation-response genes are under particularly strong sequence and expression constraints.
  • Article
    Variation in glider-detected North Atlantic right, blue, and fin whale calls in proximity to high-traffic shipping lanes
    (Inter-Research Science Publisher, 2024-06-13) Indeck, Katherine L. ; Gehrmann, Romina ; Richardson, A. L. ; Barclay, David R. ; Baumgartner, Mark F. ; Nolet, Veronique ; Davies, Kimberley T.A.
    Passive acoustic monitoring has become an integral tool for determining the presence, distribution, and behavior of vocally active cetacean species. Acoustically equipped underwater gliders are becoming a routine monitoring platform, because they can cover large spatial scales during a single deployment and have the capability to relay data to shore in near real-time. Yet, more research is needed to determine what information can be derived from glider-recorded cetacean detections. Here, a Slocum glider that monitored continuously for low frequency (<1 kHz) baleen whale vocalizations was deployed across the Honguedo Strait and the associated traffic separation scheme in the Gulf of St. Lawrence, Canada, during September and October 2019. We conducted a manual analysis of the archived audio to examine spatial and temporal variation in acoustic detection rates of North Atlantic right whales (NARWs), blue whales, and fin whales. Call detections of blue and fin whales demonstrated that both species were acoustically active throughout the deployment. Environmental association models suggested their preferential use of foraging areas along the southern slopes of the Laurentian Channel. Results also indicate that elevated background noise levels in the shipping lanes from vessel traffic only minimally influenced the likelihood of detecting blue whale acoustic presence, while they did not affect fin whale detectability. NARWs were definitively detected on less than 20% of deployment days, so only qualitative assessments of their presence were described. Nevertheless, detections of all 3 species highlight that their movements throughout this seasonally important region overlap with a high volume of vessel traffic, increasing their risk of ship strike.
  • Article
    Distinct evolutionary lineages of Schistocephalus parasites infecting co-occurring sculpin and stickleback fishes in Alaska
    (Cambridge University Press, 2024-05-09) Heins, David C. ; Moody, Kristine N. ; Arostegui, Martin C. ; Harmon, Brian S. ; Blum, Michael J. ; Quinn, Thomas P.
    Sculpins (coastrange and slimy) and sticklebacks (ninespine and threespine) are widely distributed fishes cohabiting 2 south-central Alaskan lakes (Aleknagik and Iliamna), and all these species are parasitized by cryptic diphyllobothriidean cestodes in the genus Schistocephalus. The goal of this investigation was to test for host-specific parasitic relationships between sculpins and sticklebacks based upon morphological traits (segment counts) and sequence variation across the NADH1 gene. A total of 446 plerocercoids was examined. Large, significant differences in mean segment counts were found between cestodes in sculpin (mean = 112; standard deviation [s.d.] = 15) and stickleback (mean = 86; s.d. = 9) hosts within and between lakes. Nucleotide sequence divergence between parasites from sculpin and stickleback hosts was 20.5%, and Bayesian phylogenetic analysis recovered 2 well-supported clades of cestodes reflecting intermediate host family (i.e. sculpin, Cottidae vs stickleback, Gasterosteidae). Our findings point to the presence of a distinct lineage of cryptic Schistocephalus in sculpins from Aleknagik and Iliamna lakes that warrants further investigation to determine appropriate evolutionary and taxonomic recognition.
  • Article
    Predicting metabolic modules in incomplete bacterial genomes with MetaPathPredict
    (eLife Sciences Publications, 2024-05-02) Geller-McGrath, David ; Konwar, Kishori M. ; Edgcomb, Virginia P. ; Pachiadaki, Maria G. ; Roddy, Jack W. ; Wheeler, Travis J. ; McDermott, Jason E.
    The reconstruction of complete microbial metabolic pathways using ‘omics data from environmental samples remains challenging. Computational pipelines for pathway reconstruction that utilize machine learning methods to predict the presence or absence of KEGG modules in incomplete genomes are lacking. Here, we present MetaPathPredict, a software tool that incorporates machine learning models to predict the presence of complete KEGG modules within bacterial genomic datasets. Using gene annotation data and information from the KEGG module database, MetaPathPredict employs deep learning models to predict the presence of KEGG modules in a genome. MetaPathPredict can be used as a command line tool or as a Python module, and both options are designed to be run locally or on a compute cluster. Benchmarks show that MetaPathPredict makes robust predictions of KEGG module presence within highly incomplete genomes.
  • Article
    Ecological connectivity in Pacific deep-sea hydrothermal vent metacommunities
    (Inter-Research Science Publisher, 2024-03-13) Fleming, Bethany F. M. ; Beaulieu, Stace E. ; Mills, Susan W. ; Gaggiotti, Oscar E. ; Mullineaux, Lauren S.
    Larval dispersal and connectivity between patchy, transient, deep-sea hydrothermal vent communities are important for persistence and recovery from disturbance. We investigated connectivity in vent metacommunities using the taxonomic similarity between larvae and adults to estimate the extent of exchange between communities and determine the relative roles of larval dispersal and environmental limitations (species sorting) in colonization. Connectivity at vent fields in 3 Pacific regions, Pescadero Basin, northern East Pacific Rise (EPR), and southern Mariana Trough, varied substantially and appeared to be driven by different processes. At Pescadero Basin, larval and adult taxa were similar, despite the existence of nearby (within 75 km) vent communities with different species composition, indicating limited larval transport and low connectivity. At EPR, larval and adult taxa differed significantly, despite the proximity of nearby vents with similar benthic composition, indicating substantial larval transport and potentially strong species sorting, but other factors may also explain these results. At the Mariana Trough, the larvae and adults differed significantly, indicating high larval transport but environmental limitations on colonization. We demonstrate that analysis of routinely collected samples and observations provides an informative indicator of metacommunity connectivity and insights into drivers of community assembly.
  • Article
    Temperature-dependent mixotrophy in natural populations of the toxic dinoflagellate Karenia brevis
    (MDPI, 2024-05-29) Ahn, So Hyun ; Glibert, Patricia M.
    Previous studies have revealed that mixotrophs can become more heterotrophic as the temperature rises, although these studies were primarily conducted under laboratory conditions with temperature-acclimated grazers. This study investigated the short-term thermal regulation of grazing and photosynthetic performance, measured in terms of the maximum relative electron transport rate (rETRmax), of natural Karenia brevis populations on cultured Synechococcus. Bloom waters were collected in Sarasota, Florida, during the fall of 2022. Synechococcus were inoculated into K. brevis bloom waters in varying ratios and incubated at an ambient temperature and an ambient temperature ±5 °C (19, 24, and 29 °C). In general, the grazing coefficient, clearance, and ingestion rates were higher in warmer waters, although ingestion rates were significantly regulated by the prey-to-grazer ratios and, to a lesser degree, by temperatures (22 to 204 Synechococcus K. brevis−1 d−1). Overall, the rETRmax of Synechococcus controls generally increased over time with a more substantial increase at warmer temperatures, but, in the presence of grazers, the rETRmax of Synechococcus did not increase, and, remarkably, even decreased in some cases. These findings suggest that grazing on Synechococcus could directly regulate Synechococcus concentrations and indirectly reduce the photosynthetic performance of prey. Furthermore, this study demonstrates that the thermal regulation of grazing and photosynthetic performance can occur on a short-term basis.
  • Preprint
    Advancing the frontier of fish geolocation into the ocean’s midwaters
    (Elsevier, 2024-08-24) Arostegui, Martin C.
    Tracking large-scale movements of fishes in the ocean’s midwaters, below the euphotic zone and above the seafloor, is extremely challenging. Archival satellite telemetry devices rely on light, sea surface temperature, or bottom depth data to estimate location. Consequently, geolocation of fishes inhabiting the twilight (mesopelagic: 200–1000 m) and midnight (bathypelagic: 1000–4000 m) zones has been restricted to hypothesized movement routes, thereby precluding a baseline ecological understanding against which to assess potential anthropogenic impacts. We assessed the viability of comparing depth-temperature profiles measured by animal-borne satellite tags against those from 3D ocean-resolving models and incorporated known locations from acoustic telemetry to enable a quantitative framework for deep-sea geolocation. Testing of alternative, data-driven likelihood scenarios on a deep-water shark species assemblage with marked variation in modal depth distributions confirmed that the methodological frontier of geolocation can be advanced into the twilight and midnight zones. We identify key limitations in deep-water geolocation, and ways to overcome them, identifying a viable path for robust location estimates that can help address the knowledge gap on fish movement ecology in the deep sea. Our findings suggest that leveraging state-of-the-art geolocation approaches, in combination with novel technologies, raises new opportunities for studying enigmatic deep-ocean ecosystems.
  • Preprint
    Cranial endothermy in mobulid rays: Evolutionary and ecological implications of a thermogenic brain
    (Wiley, 2024-10-21) Arostegui, Martin C.
    1. The large, metabolically expensive brains of manta and devil rays (Mobula spp.) may act as a thermogenic organ representing a unique mechanistic basis for cranial endothermy among fishes that improves central nervous system function in cold waters. 2. Whereas early hominids in hot terrestrial environments may have experienced a thermal constraint to evolving larger brain size, cetaceans and mobulids in cold marine waters may have experienced a thermal driver for enlargement of a thermogenic brain. 3. The potential for brain enlargement to yield the dual outcomes of cranial endothermy and enhanced cognition in mobulids suggests one may be an evolutionary by-product of selection for the mechanisms underlying the other, and highlights the need to account for non-cognitive functions when translating brain size into cognitive capacity. 4. Computational scientific imaging offers promising avenues for addressing the pressing mechanistic and phylogenetic questions needed to assess the theory that cranial endothermy in mobulids is the result of temperature-driven selection for a brain with augmented thermogenic potential.
  • Article
    Caller identification and characterization of individual humpback whale acoustic behaviour
    (Royal Society of Chemistry, 2024-03-13) Zeh, Julia M. ; Perez-Marrufo, Valeria ; Adcock, Dana L. ; Jensen, Frants H. ; Knapp, Kaitlyn J. ; Robbins, Jooke ; Tackaberry, Jennifer E. ; Weinrich, Mason T. ; Friedlaender, Ari S. ; Wiley, David N. ; Parks, Susan E.
    Acoustic recording tags provide fine-scale data linking acoustic signalling with individual behaviour; however, when an animal is in a group, it is challenging to tease apart calls of conspecifics and identify which individuals produce each call. This, in turn, prohibits a robust assessment of individual acoustic behaviour including call rates and silent periods, call bout production within and between individuals, and caller location. To overcome this challenge, we simultaneously instrumented small groups of humpback whales on a western North Atlantic feeding ground with sound and movement recording tags. This approach enabled a comparison of the relative amplitude of each call across individuals to infer caller identity for 97% of calls. We recorded variable call rates across individuals (mean = 23 calls/h) and groups (mean = 55 calls/h). Calls were produced throughout dives, and most calls were produced in bouts with short inter-call intervals of 2.2 s. Most calls received a likely response from a conspecific within 100 s. This caller identification (ID) method facilitates studying both individual- and group-level acoustic behaviour, yielding novel results about the nature of sequence production and vocal exchanges in humpback whale social calls. Future studies can expand on these caller ID methods for understanding intra-group communication across taxa.
  • Article
    Allochrony is shaped by foraging niche segregation rather than adaptation to the windscape in long-ranging seabirds
    (BMC, 2024-04-02) Ventura, Francesco ; Granadeiro, Jose Pedro ; Catry, Paulo ; Gjerdrum, Carina ; De Pascalis, Federico ; Viveiros, Filipe ; Silva, Isamberto ; Menezes, Dilia ; Paiva, Vitor H. ; Silva, Monica C.
    Ecological segregation allows populations to reduce competition and coexist in sympatry. Using as model organisms two closely related gadfly petrels endemic to the Madeira archipelago and breeding with a two month allochrony, we investigated how movement and foraging preferences shape ecological segregation in sympatric species. We tested the hypothesis that the breeding allochrony is underpinned by foraging niche segregation. Additionally, we investigated whether our data supported the hypothesis that allochrony is driven by species-specific adaptations to different windscapes.
  • Article
    The impact of boldness on demographic rates and life‐history outcomes in the wandering albatross
    (British Ecological Society, 2024-03-25) Van de Walle, Joanie ; Sun, Ruijiao ; Fay, Remi ; Patrick, Samantha C. ; Barbraud, Christophe ; Delord, Karine ; Weimerkirch, Henri ; Jenouvrier, Stephanie
    Differences among individuals within a population are ubiquitous. Those differences are known to affect the entire life cycle with important consequences for all demographic rates and outcomes. One source of among-individual phenotypic variation that has received little attention from a demographic perspective is animal personality, which is defined as consistent and heritable behavioural differences between individuals. While many studies have shown that individual variation in individual personality can generate individual differences in survival and reproductive rates, the impact of personality on all demographic rates and outcomes remains to be assessed empirically. Here, we used a unique, long-term, dataset coupling demography and personality of wandering albatross (Diomedea exulans) in the Crozet Archipelago and a comprehensive analysis based on a suite of approaches (capture-mark-recapture statistical models, Markov chains models and structured matrix population models). We assessed the effect of boldness on annual demographic rates (survival, breeding probability, breeding success), life-history outcomes (life expectancy, lifetime reproductive outcome, occupancy times), and an integrative demographic outcome (population growth rate). We found that boldness had little impact on female demographic rates, but was very likely associated with lower breeding probabilities in males. By integrating the effects of boldness over the entire life cycle, we found that bolder males had slightly lower lifetime reproductive success compared to shyer males. Indeed, bolder males spent a greater proportion of their lifetime as non-breeders, which suggests longer inter-breeding intervals due to higher reproductive allocation. Our results reveal that the link between boldness and demography is more complex than anticipated by the pace-of-life literature and highlight the importance of considering the entire life cycle with a comprehensive approach when assessing the role of personality on individual performance and demography.
  • Article
    Proteomics analysis reveals differential acclimation of coastal and oceanic Synechococcus to climate warming and iron limitation
    (Frontiers Media, 2024-02-20) Schiksnis, Cara ; Xu, Min ; Saito, Mak A. ; McIlvin, Matthew R. ; Moran, Dawn M. ; Bian, Xiaopeng ; John, Seth G. ; Zheng, Qiang ; Yang, Nina ; Fu, Feixue ; Hutchins, David A.
    In many oceanic regions, anthropogenic warming will coincide with iron (Fe) limitation. Interactive effects between warming and Fe limitation on phytoplankton physiology and biochemical function are likely, as temperature and Fe availability affect many of the same essential cellular pathways. However, we lack a clear understanding of how globally significant phytoplankton such as the picocyanobacteria Synechococcus will respond to these co-occurring stressors, and what underlying molecular mechanisms will drive this response. Moreover, ecotype-specific adaptations can lead to nuanced differences in responses between strains. In this study, Synechococcus isolates YX04-1 (oceanic) and XM-24 (coastal) from the South China Sea were acclimated to Fe limitation at two temperatures, and their physiological and proteomic responses were compared. Both strains exhibited reduced growth due to warming and Fe limitation. However, coastal XM-24 maintained relatively higher growth rates in response to warming under replete Fe, while its growth was notably more compromised under Fe limitation at both temperatures compared with YX04-1. In response to concurrent heat and Fe stress, oceanic YX04-1 was better able to adjust its photosynthetic proteins and minimize the generation of reactive oxygen species while reducing proteome Fe demand. Its intricate proteomic response likely enabled oceanic YX04-1 to mitigate some of the negative impact of warming on its growth during Fe limitation. Our study highlights how ecologically-shaped adaptations in Synechococcus strains even from proximate oceanic regions can lead to differing physiological and proteomic responses to these climate stressors.
  • Article
    Decreasing body size is associated with reduced calving probability in critically endangered North Atlantic right whales
    (Royal Society of Chemistry, 2024-02-28) Pirotta, Enrico ; Tyack, Peter L. ; Durban, John W. ; Fearnbach, Holly ; Hamilton, Philip K. ; Harris, Catriona M. ; Knowlton, Amy R. ; Kraus, Scott D. ; Miller, Carolyn A. ; Moore, Michael J. ; Pettis, Heather M. ; Photopoulou, Theoni ; Rolland, Rosalind M. ; Schick, Robert S. ; Thomas, Len
    Body size is key to many life-history processes, including reproduction. Across species, climate change and other stressors have caused reductions in the body size to which animals can grow, called asymptotic size, with consequences for demography. A reduction in mean asymptotic length was documented for critically endangered North Atlantic right whales, in parallel with declines in health and vital rates resulting from human activities and environmental changes. Here, we tested whether smaller body size was associated with lower reproductive output, using a state-space model for individual health, survival and reproduction that quantifies the mechanistic links between these processes. Body size (as represented by the cube of length) was strongly associated with a female's calving probability at each reproductive opportunity. This relationship explained 62% of the variation in calving among reproductive females, along with their decreasing health (20%). The effects of decreasing mean body size on reproductive performance are another concerning indication of the worsening prospects for this species and many others affected by environmental change, requiring a focus of conservation and management interventions on improving conditions that affect reproduction as well as reducing mortality.
  • Article
    Shift from income breeding to capital breeding with latitude in the invasive Asian shore crab Hemigrapsus sanguineus
    (Nature Research, 2024-03-20) Reese, Tanner C. ; Blakeslee, April M. H. ; Crane, Laura C. ; Fletcher, Laura S. ; Repetto, Michele F. ; Smith, Nanette ; Stancil, Carter ; Tepolt, Carolyn K. ; Toscano, Benjamin J. ; Griffen, Blaine D.
    Organisms vary in the timing of energy acquisition and use for reproduction. Thus, breeding strategies exist on a continuum, from capital breeding to income breeding. Capital breeders acquire and store energy for breeding before the start of the reproductive season, while income breeders finance reproduction using energy acquired during the reproductive season. Latitude and its associated environmental drivers are expected to heavily influence breeding strategy, potentially leading to latitudinal variation in breeding strategies within a single species. We examined the breeding strategy of the Asian shore crab Hemigrapsus sanguineus at five sites spanning nearly 10° of latitude across its invaded United States range. We hypothesized that the primary breeding strategy of this species would shift from income breeding to capital breeding as latitude increases. We found that though this species’ breeding strategy is dominated by capital breeding throughout much of the range, income breeding increases in importance at lower latitudes. This latitudinal pattern is likely heavily influenced by the duration of the foraging and breeding seasons, which also vary with latitude. We also found that reproductive characteristics at the northern and southern edges of the invaded range were consistent with continued range expansion. We suggest that the reproductive flexibility of the Asian shore crab is a key facilitator of its continued invasion success. Our results highlight the influence of latitude on the breeding strategy of a species and emphasize the need for further research regarding the ecological importance and implications of flexibility in breeding strategies within species.
  • Article
    Advances in remote sensing of emperor penguins: First multi-year time series documenting trends in the global population
    (The Royal Society, 2024-03-13) LaRue, Michelle ; Iles, David T. ; Labrousse, Sara ; Fretwell, Peter T. ; Ortega, David ; Devane, Eileen ; Horstmann, Isabella ; Viollat, Lise ; Foster-Dyer, Rose ; Le Bohec, Celine ; Zitterbart, Daniel ; Houstin, Aymeric ; Richter, Sebastian ; Winterl, Alexander ; Wienecke, Barbara ; Salas, Leo ; Nixon, Monique ; Barbraud, Christophe ; Kooyman, Gerald L. ; Ponganis, Paul J. ; Ainley, David G. ; Trathan, Philip ; Jenouvrier, Stephanie
    Like many polar animals, emperor penguin populations are challenging to monitor because of the species' life history and remoteness. Consequently, it has been difficult to establish its global status, a subject important to resolve as polar environments change. To advance our understanding of emperor penguins, we combined remote sensing, validation surveys and using Bayesian modelling, we estimated a comprehensive population trajectory over a recent 10-year period, encompassing the entirety of the species’ range. Reported as indices of abundance, our study indicates with 81% probability that there were fewer adult emperor penguins in 2018 than in 2009, with a posterior median decrease of 9.6% (95% credible interval (CI) −26.4% to +9.4%). The global population trend was −1.3% per year over this period (95% CI = −3.3% to +1.0%) and declines probably occurred in four of eight fast ice regions, irrespective of habitat conditions. Thus far, explanations have yet to be identified regarding trends, especially as we observed an apparent population uptick toward the end of time series. Our work potentially establishes a framework for monitoring other Antarctic coastal species detectable by satellite, while promoting a need for research to better understand factors driving biotic changes in the Southern Ocean ecosystem.