McMonagle
Helena I.
McMonagle
Helena I.
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ArticleOtolith characterization and integrative species identification of adult mesopelagic fishes from the western North Atlantic Ocean(Frontiers Media, 2023-08-21) Quigley, Lucinda A. ; Caiger, Paul E. ; Govindarajan, Annette F. ; McMonagle, Helena I. ; Jech, J. Michael ; Lavery, Andone C. ; Sosik, Heidi M. ; Llopiz, Joel K.Fish diversity and ecology in the ocean’s mesopelagic zone are understudied compared to other marine regions despite growing interest in harvesting these potential resources. Otoliths can provide a wealth of taxonomic and life history information about fish, which can help fill these knowledge gaps; however, there has been relatively little research to date on the otoliths of mesopelagic species. Here, a species-specific image library was assembled of sagittal otoliths from 70 mesopelagic fishes belonging to 29 families collected in the western North Atlantic Ocean. Images of adult sagittal otoliths from 12 species were documented and photographed for the first time. The fish were identified to species with a combination of morphological characters and DNA barcoding. Regressions between otolith size and fish length are presented for the six species with the largest sample sizes in this study. This otolith image library, coupled with otolith-length and width to fish-length relationships, can be used for prey identification and back-calculation of fish size, making it a valuable tool for studies relating to food webs in the important yet poorly understood mesopelagic zone. In addition, the 44 fish barcodes generated in this study highlight the benefit of using an integrative taxonomic approach to studies of this nature, as well as add to existing public databases that enable cryptic species and metabarcoding analyses of mesopelagic species.
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ArticleHigh uncertainty in fish bioenergetics impedes precision of fish-mediated carbon transport estimates into the ocean’s twilight zone(Elsevier, 2023-07-07) McMonagle, Helena I. ; Llopiz, Joel K. ; Hilborn, Ray ; Essington, Timothy E.Mesopelagic fishes may contribute substantially to marine carbon transport by consuming organic carbon near the surface at night and releasing it in the mesopelagic zone during the day. However, the magnitude and uncertainties associated with this transport are not well understood; fish-mediated carbon flux estimates range from less than 1 % to greater than 30 % of biologically-driven carbon export out of the epipelagic zone. While total mesopelagic fish biomass is an important source of uncertainty, information on fish bioenergetics and movement might also limit the precision of carbon transport estimates. Here, we ask how uncertainties in fish bioenergetics and behaviors affect carbon flux estimation, and which processes contribute most to uncertainty. We used sensitivity analyses to reveal that modeled carbon flux was most sensitive to respiration-related parameters, and per capita fish carbon flux estimates varied six-fold over the range of plausible parameter values. Biomass estimation can add at least ten-fold variation in ecosystem-scale carbon flux estimates. We conclude that it is not currently possible to estimate fish-mediated carbon flux precisely, but estimates may be constrained through future empirical work on the most influential parameters.
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ArticleAssessing mesopelagic fish diversity and diel vertical migration with environmental DNA(Frontiers Media, 2023-12-11) Govindarajan, Annette F. ; Llopiz, Joel K. ; Caiger, Paul E. ; Jech, J. Michael ; Lavery, Andone C. ; McMonagle, Helena I. ; Wiebe, Peter H. ; Zhang, Weifeng GordonMesopelagic fishes are an important component of the world’s oceans in terms of their abundance, biomass, and ecosystem function. These fishes are important contributors to the biological carbon pump via their feeding and behaviors, whereby they facilitate the transfer of carbon from shallow waters to the deep sea. Several species undertake diel vertical migration, feeding in shallower waters at night and moving to deeper waters during the day. This process actively expedites the downward flux of carbon. However, carbon budgets and climate models require accurate information regarding the depth distributions and migration patterns of these fishes, and environmental DNA (eDNA) analyses can provide this information. Here, we utilize eDNA approaches, generating taxonomically-informative COI and 12S reference barcodes for 80 species of mesopelagic fishes, which can be used for species-level identification of eDNA sequences. Using these, along with a publicly available barcodes database, we compare results from eDNA analysis with traditional net sampling, and explore the ability of eDNA techniques to detect diel vertical migration in fishes from samples collected in Northwest Atlantic Slope Water. We found that eDNA and net samples often resulted in different species identifications, demonstrating that eDNA can detect species that would otherwise be missed with traditional methods. In our eDNA samples, we also detected more species (12) in our shallowest depth category (0 - 100 m) from night samples than from day samples (3). This is consistent with increased diversity in shallow waters at night due to diel vertical migration. Based on the variability observed in sample duplicates, we suggest that future mesopelagic eDNA studies incorporate larger sample volumes and scaled-up sampling efforts. We also note the potential applications of eDNA analysis in addressing ecological questions related to predator-prey relationships identification of foraging hotspots, and carbon flow through the ocean’s midwaters.
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ArticleFive reasons to take the precautionary approach to deep sea exploitation(Nature Research, 2023-05-05) Bisson, Kelsey ; McMonagle, Helena ; Iglesias, Ilysa ; Halfter, Svenja ; Gallo, NatalyaExtractive activities in the deep sea are poised to advance faster than the science needed to evaluate risks. Here, we call for a strong precautionary approach in developing these industries. Food and energy insecurity have been exacerbated by climate change, conflict, and disease, with global energy demands only expected to grow. Seabed mining and deep-sea fishing have been suggested as ways to support shifting to renewable energy and increasing food supply. These industries are likely to impact one of the largest habitats on Earth, our ocean’s mesopelagic zone, at depths between ~200 and 1000 m. Once assumed to be lifeless, we now know the mesopelagic zone is rich with life and a vital component of the global ecosystem. Recently, industries have begun exploratory extractive activities, while our scientific understanding of the impacts of these activities on the mesopelagic zone is trailing behind (Fig. 1). Here, we outline five reasons why we advocate for a precautionary approach to deep-sea exploitation in order to make evidence-based decisions.
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ArticleWhen to add a new process to a model - and when not: a marine biogeochemical perspective(Elsevier, 2024-09-24) Martin, Adrian P. ; Bahamondes Dominguez, Angela ; Baker, Chelsey A. ; Baumas, Chloe M. J. ; Bisson, Kelsey M. ; Cavanf, Emma ; Freilich, Mara A, ; Galbraith, Eric D. ; Galii, Marti ; Henson, Stephanie A. ; Kvale, Karin F. ; Lemmen, Carsten ; Luo, Jessica Y. ; McMonagle, Helena I. ; de Melo Virissimo, Francisco ; Moller, Klas O. ; Richon, Camille ; Suresh, Iyyappan ; Wilson, Jamie D. ; Woodstock, Matthew S. ; Yool, AndrewModels are critical tools for environmental science. They allow us to examine the limits of what we think we know and to project that knowledge into situations for which we have little or no data. They are by definition simplifications of reality. There are therefore inevitably times when it is necessary to consider adding a new process to a model that was previously omitted. Doing so may have consequences. It can increase model complexity, affect the time a model takes to run, impact the match between the model output and observations, and complicate comparison to previous studies using the model. How a decision is made on whether to add a process is no more objective than how a scientist might design a laboratory experiment. To illustrate this, we report on an event where a broad and diverse group of marine biogeochemists were invited to construct flowcharts to support making the decision of when to include a new process in a model. The flowcharts are used to illustrate both the complexity of factors that modellers must consider prior to making a decision on model development and the diversity of perspectives on how that decision should be reached. The purpose of this paper is not to provide a definitive protocol for making that decision. Instead, we argue that it is important to acknowledge that there is no objectively “best” approach and instead we discuss the flowcharts created as a means of encouraging modellers to think through why and how they are doing something. This may also hopefully guide observational scientists to understand why it may not always be appropriate to include a process they are studying in a model.
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ArticleQuantifying uncertainty in the contribution of mesopelagic fishes to the biological carbon pump in the Northeast Atlantic Ocean(Oxford University Press, 2024-11-07) McMonagle, Helena I. ; Llopiz, Joel K. ; Maas, Amy E. ; Steinberg, Deborah K. ; Govindarajan, Annette F. ; Essington, Timothy E.Mesopelagic fishes may contribute substantially to marine carbon export and sequestration. However, uncertainty in this contribution due to limited precision of mesopelagic biomass and bioenergetic rate estimates has not been thoroughly quantified for any study site. Datasets that can confront these challenges are rare, particularly for comparing fish-mediated carbon flux to other biological carbon pump pathways. Using data from a unique three-ship expedition in spring 2021 in the subarctic Northeast Atlantic Ocean, we compare carbon transported by adult fish, zooplankton, and sinking particles, and calculate uncertainty in the relative contribution of fishes. Results indicate biomass- and bioenergetic-based uncertainty contributed roughly equally to variance in estimated carbon transport. The plausible range of mesopelagic fish carbon flux spans an order of magnitude: 1.6–21 mg C m−2 d−1 to 200 m depth and 0.52–9.6 mg C m−2 d−1 to 500 m. Fishes contributed ∼0.52%–18% at 200 m to the total biological carbon pump, and ∼0.43%–13% at 500 m. Of the fish-mediated carbon transport to 200 m, ∼8%–30% is sequestered on climate-relevant time scales (>100 years). This reinforces that carbon transport should not be conflated with carbon sequestration. These findings have implications for prioritizing future empirical measurements, evaluating trade-offs in fisheries management, and understanding the role of fishes in the biological carbon pump.
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ArticleMetabarcoding and morphological analysis of diets of mesopelagic fishes in the NW Atlantic Slope Water(Frontiers Media, 2024-10-04) Bucklin, Ann ; Batta-Lona, Paola G. ; Questel, Jennifer M. ; McMonagle, Helena ; Wojcicki, Melissa ; Llopiz, Joel K. ; Glancy, Sarah ; Caiger, Paul E. ; Francolini, Rene ; Govindarajan, Annette ; Thorrold, Simon R. ; Jech, Michael ; Wiebe, Peter H.DNA metabarcoding and morphological taxonomic (microscopic) analysis of the gut contents was used to examine diet diversity of seven species of fishes collected from mesopelagic depths (200-1000 m) in the NW Atlantic Ocean Slope Water during Summer 2018 and 2019. Metabarcoding used two gene regions: V9 hypervariable region of nuclear 18S rRNA and mitochondrial cytochrome oxidase I (COI). V9 sequences were classified into 14 invertebrate prey groups, excluding fish due to predator swamping. Ecological network analysis was used to evaluate relative strengths of predator-prey linkages. Multivariate statistical analysis revealed consistently distinct diets of four fish species in 2018 and/or 2019: Argyropelecus aculeatus, Chauliodus sloani, Hygophum hygomii, and Sigmops elongatus. Three other species analyzed (Malacosteus niger, Nemichthys scolopaceus, and Scopelogadus beanii) showed more variability between sampling years. COI sequences were classified into eight invertebrate prey groups, within which prey species were detected and identified. Considering all predator species together, a total of 77 prey species were detected with a minimum of 1,000 COI sequences, including 22 copepods, 18 euphausiids, and 7 amphipods. Morphological prey counts were classified into seven taxonomic groups, including a gelatinous group comprised of soft-bodied organisms. The ocean twilight zone or is home to exceptional diversity and biomass of marine fish, which are key players in deep sea food webs. This study used integrative morphological-molecular analysis to provide new insights into trophic relationships and sources of productivity for mesopelagic fishes, including identification of key prey species, recognition of the importance of gelatinous prey, and characterization of differences in diet among fish predators in the NW Atlantic Slope Water.