Ecological characteristics of eucalanoid copepods of the eastern tropical North Pacific Ocean: Adaptations for life within a low oxygen system

Cass, Christine J.; Daly, Kendra L.

doi:10.1016/j.jembe.2015.04.005

Cited by 10 publications

(14 citation statements)

References 57 publications

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“…inermis is endemic to the ETP, occurring both north and south of the Equator (Chen, 1986;Fleminger, 1973;Goetze, 2003Goetze, , 2010Goetze and Ohman, 2010;Hidalgo et al, 2005a, b;Jackson and Smith, 2016;Sameoto, 1986). It is known to inhabit extremely low oxygen water (Boyd et al, 1980;Escribano et al, 2009;Judkins, 1980;Saltzman and Wishner, 1997;Wishner et al, 2013), as well as oxygenated depths, and has unique physiological and biochemical adaptations for the low-oxygen environment Cass and Daly, 2015). Overall population distributions at particular locations in this and prior work usually encompassed a range of oxygen concentrations, although most earlier studies had relatively broad sampling strata that did not isolate specific oxygen ranges or did not have electronic oxygen sensors colocated on the zooplankton sampling systems.…”

Section: Diapausing In the Omzmentioning

confidence: 99%

Ocean deoxygenation and copepods: coping with oxygen minimum zone variability

2020

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Abstract. Increasing deoxygenation (loss of oxygen) of the ocean, including expansion of oxygen minimum zones (OMZs), is a potentially important consequence of global warming. We examined present-day variability of vertical distributions of 23 calanoid copepod species in the Eastern Tropical North Pacific (ETNP) living in locations with different water column oxygen profiles and OMZ intensity (lowest oxygen concentration and its vertical extent in a profile). Copepods and hydrographic data were collected in vertically stratified day and night MOCNESS (Multiple Opening/Closing Net and Environmental Sensing System) tows (0–1000 m) during four cruises over a decade (2007–2017) that sampled four ETNP locations: Costa Rica Dome, Tehuantepec Bowl, and two oceanic sites further north (21–22∘ N) off Mexico. The sites had different vertical oxygen profiles: some with a shallow mixed layer, abrupt thermocline, and extensive very low oxygen OMZ core; and others with a more gradual vertical development of the OMZ (broad mixed layer and upper oxycline zone) and a less extensive OMZ core where oxygen was not as low. Calanoid copepod species (including examples from the genera Eucalanus, Pleuromamma, and Lucicutia) demonstrated different distributional strategies (implying different physiological characteristics) associated with this variability. We identified sets of species that (1) changed their vertical distributions and depth of maximum abundance associated with the depth and intensity of the OMZ and its oxycline inflection points; (2) shifted their depth of diapause; (3) adjusted their diel vertical migration, especially the nighttime upper depth; or (4) expanded or contracted their depth range within the mixed layer and upper part of the thermocline in association with the thickness of the aerobic epipelagic zone (habitat compression concept). These distribution depths changed by tens to hundreds of meters depending on the species, oxygen profile, and phenomenon. For example, at the lower oxycline, the depth of maximum abundance for Lucicutia hulsemannae shifted from ∼600 to ∼800 m, and the depth of diapause for Eucalanus inermis shifted from ∼500 to ∼775 m, in an expanded OMZ compared to a thinner OMZ, but remained at similar low oxygen levels in both situations. These species or life stages are examples of “hypoxiphilic” taxa. For the migrating copepod Pleuromamma abdominalis, its nighttime depth was shallow (∼20 m) when the aerobic mixed layer was thin and the low-oxygen OMZ broad, but it was much deeper (∼100 m) when the mixed layer and higher oxygen extended deeper; daytime depth in both situations was ∼300 m. Because temperature decreased with depth, these distributional depth shifts had metabolic implications. The upper ocean to mesopelagic depth range encompasses a complex interwoven ecosystem characterized by intricate relationships among its inhabitants and their environment. It is a critically important zone for oceanic biogeochemical and export processes and hosts key food web components for commercial fisheries. Among the zooplankton, there will likely be winners and losers with increasing ocean deoxygenation as species cope with environmental change. Changes in individual copepod species abundances, vertical distributions, and life history strategies may create potential perturbations to these intricate food webs and processes. Present-day variability provides a window into future scenarios and potential effects of deoxygenation.

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Section: Diapausing In the Omzmentioning

confidence: 99%

Ocean deoxygenation and copepods: coping with oxygen minimum zone variability

2020

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“…Based on previously recorded vertical distributions of mesozooplankton, such low concentrations of Chl a may have resulted in changes in the abundance and distributions of some endemic mesozooplankton. The abundance and vertical distribution of the copepod family Eucalanidae, a family that includes Eucalanus, Subeucalanus and Pareucalanus (Cass, 2011;Cass and Daly, 2015), have been studied recently during fall/winter cruises (from 2007 to 2009) in the CRD area of the Eastern Tropical North Pacific (ETNP) Ocean (Cass et al, 2014;Cass and Daly, 2015). These studies determined that Eucalanus inermis, Subeucalanus subtenuis, Pareucalanus attenuatus and Rhincalanus spp.…”

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confidence: 99%

“…These studies determined that Eucalanus inermis, Subeucalanus subtenuis, Pareucalanus attenuatus and Rhincalanus spp. formed four groups of differing ecological strategies in the ETP based on their biochemical, physiological and behavioral characteristics (Cass and Daly, 2015). For example, Pareucalanus attenuatus and E. inermis have jelly-like bodies and lowprotein levels, allowing them to have lower metabolic oxygen demands, where S. subtenuis have no or few biochemical or physiological strategies to cope with low oxygen (Cass and Daly, 2015).…”

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Vertical distribution of Eucalanoid copepods within the Costa Rica Dome area of the Eastern Tropical Pacific

Jackson

Smith

2016

J. Plankton Res.

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A variety of ecological strategies for tolerance of low-oxygen conditions within the Costa Rica Dome (CRD) area of the Eastern Tropical Pacific are documented for the copepod family Eucalanidae. During the summer of 2010, we compared the ecological strategies used by the Eucalanidae inside and outside the central CRD region. We compared the vertical and horizontal distributions of five species, ,, , and together with species, in the epipelagic (upper 200 m) among four locations, which we grouped into a section roughly crossing the core CRD area (inside-outside core CRD). The coastal area outside the CRD supported the most diverse assemblage, whereas overall abundance of Eucalanidae in the central CRD was 2-fold greater than outside and dominated by (>60%). Eucalanidae in the central CRD had a shallow depth distribution, closely associated with the shallow thermocline (10-20 m). There was no evidence of daily vertical migration in the central CRD, but demonstrated vertical migration outside the CRD. The vertical abundance patterns of Eucalanidae in the CRD region reflect complex interactions between subtle physical-chemical differences and food resources.

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“…Colors are scaled to the mean fraction above or below the pycnocline, with the value shown in each leaf region. Minimum leaf size was n = 12 liance on burst swimming activity or an adaptation to lower oxygen conditions, but it has been shown to have higher activity in copepods found in or migrating through deoxygenated conditions (Teuber et al 2013, Cass & Daly 2015, and it may provide another metric useful in future studies as a means to assess re sponses to deoxygenation beyond oxygen consumption. Size has also been shown to affect migration behaviors, with larger animals delaying migration in euphausiids (De Robertis et al 2000, De Robertis 2002.…”

Section: Discussionmentioning

confidence: 99%

Synergistic effects of seasonal deoxygenation and temperature truncate copepod vertical migration and distribution

Pierson¹,

Slater²,

Elliott³

et al. 2017

Mar. Ecol. Prog. Ser.

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The vertical distribution of copepods in coastal and estuarine systems is altered by the concentration of dissolved oxygen in the water column. We studied the combined effects of temperature and dissolved oxygen on vertical distribution and migration behavior of the copepod Acartia tonsa in the Chesapeake Bay throughout the period of seasonal deoxygenation in 2010 and 2011. Vertically stratified net tows and hydrographic casts were conducted at 2 stations over diel cycles in spring, summer, and autumn. The partial pressure of dissolved oxygen (pO 2 ) was used as a metric for the condition of copepod habitat during each cruise instead of oxygen concentration, because partial pressure incorporates the temperature dependence of dissolved oxygen solubility, making it a more useful indication of available oxygen supply than concentration. Habitat conditions were described as having pO 2 above limiting conditions, below the maximum respiratory demand but above potentially lethal conditions, or below the minimum basal respiratory demand. In general, adult males were found deeper in the water than females in most oxygen conditions. Regression tree analysis supported these findings and showed that pO 2 was a key predictor of the fraction of copepodites, adult females, and adult males above the pycnocline, and for copepodites and adult females below the pycnocline. Temperature was a strong predictor of the fraction of adult males below the pycnocline, with a smaller fraction found there at higher temperatures. These findings suggest sex-specific responses to deoxygenation, potentially as a result of different oxygen demands or behavior.

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Ecological characteristics of eucalanoid copepods of the eastern tropical North Pacific Ocean: Adaptations for life within a low oxygen system

Cited by 10 publications

References 57 publications

Ocean deoxygenation and copepods: coping with oxygen minimum zone variability

Ocean deoxygenation and copepods: coping with oxygen minimum zone variability

Vertical distribution of Eucalanoid copepods within the Costa Rica Dome area of the Eastern Tropical Pacific

Synergistic effects of seasonal deoxygenation and temperature truncate copepod vertical migration and distribution

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