Maggie D. JohnsonSmithsonian Institution · Smithsonian Marine Station (SMS) at Fort Pierce
Maggie D. Johnson
PhD Marine Biology, Scripps Institution of Oceanography
About
36
Publications
6,496
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
678
Citations
Citations since 2016
Introduction
Additional affiliations
September 2008 - June 2011
May 2008 - September 2008
September 2005 - January 2007
Publications
Publications (36)
Ocean acidification (OA) threatens the persistence of reef-building corals and the habitat they provide. While species-specific effects of OA on marine organisms could have cascading effects on ecological interactions like competition, few studies have identified how benthic reef competitors respond to OA. We explored how two common Caribbean compe...
1. Standardized metrics that quantify a component of ecosystem functioning are essential for evaluating the current status of coastal marine habitats and for monitoring how ecologically important ecosystems are changing in response to global and local environmental change. Calcification Accretion Units (CAUs) are a standardized tool for quantifying...
The marine green alga Brilliantia kiribatiensis gen. et sp. nov. is described from samples collected during two expeditions (2009, 2013) from the coral reefs of the Southern Line Islands, Republic of Kiribati, Pacific Ocean. Phylogenetic analysis of sequences of the large‐ and small‐subunit rDNA and the rDNA internal transcribed spacer region revea...
Ocean deoxygenation threatens the persistence of coastal ecosystems worldwide. Despite an increasing awareness that coastal deoxygenation impacts tropical habitats, there remains a paucity of empirical data on the effects of oxygen limitation on reef-building corals. To address this knowledge gap, we conducted laboratory experiments with ecological...
Loss of oxygen in the global ocean is accelerating due to climate change and eutrophication, but how acute deoxygenation events affect tropical marine ecosystems remains poorly understood. Here we integrate analyses of coral reef benthic communities with microbial community sequencing to show how a deoxygenation event rapidly altered benthic commun...
Ocean acidification (OA) is likely to differentially affect the biology and physiology of calcifying and non-calcifying taxa, thereby potentially altering key ecological interactions (e.g., facilitation, competition, predation) in ways that are difficult to predict from single-species experiments. We used a two-factor experimental design to investi...
Prior exposure to variable environmental conditions is predicted to influence the resilience of marine organisms to global change. We conducted complementary 4-month field and laboratory experiments to understand how a dynamic, and sometimes extreme, environment influences growth rates of a tropical reef-building crustose coralline alga and its res...
The impacts of ocean deoxygenation on biodiversity and ecosystem function are well established in temperate regions, and here we illustrate how the study of hypoxia in tropical ecosystems can offer insights of general importance. We first describe how mechanisms of resilience have developed in response to naturally occurring hypoxia across three tr...
Primary producers release oxygen as the by-product of photosynthetic light reactions during the day. However, a prevalent, globally-occurring nighttime spike in dissolved oxygen in the absence of light challenges the traditional assumption that biological oxygen production is limited to daylight hours, particularly in tropical coral reefs. Here we...
Upwelling is an important source of inorganic nutrients in marine systems, yet little is known about how gradients in upwelling affect primary producers on coral reefs. The Southern Line Islands span a natural gradient of inorganic nutrient concentrations across the equatorial upwelling region in the central Pacific. We used this gradient to test t...
Few studies have documented the spatial and temporal dynamics of highly invasive species in coral reef benthic communities. Here, we quantified the ecological dynamics of invasion by a corallimorph, Rhodactis howesii, at Palmyra Atoll in the central Pacific. A localized outbreak of this species was first observed following a shipwreck at Palmyra in...
During 2015–2016, an El Niño and associated warm water event caused widespread coral bleaching across the equatorial Pacific. Here, we combine 8 yr of benthic monitoring data from permanent photoquadrats with remotely sensed and in situ temperature measurements to assess the impact of the warming event on benthic communities at Palmyra Atoll. We qu...
On coral reefs, microorganisms are essential for recycling nutrients to primary producers through the remineralization of benthic-derived organic matter. Diel investigations of reef processes are required to holistically understand the functional roles of microbial players in these ecosystems. Here we report a metagenomic analysis characterizing mi...
Crustose coralline algae (CCA) are among the most sensitive marine taxa to the pH changes predicted with ocean acidification (OA). However, many CCA exist in habitats where diel cycles in pH can surpass near-future OA projections. The prevailing theory that natural variability increases the tolerance of calcifiers to OA has not been widely tested w...
Mixotrophy is among the most successful nutritional strategies in terrestrial and marine ecosystems. The ability of organisms to supplement primary nutritional modes along continua of autotrophy and heterotrophy fosters trophic flexibility that can sustain metabolic demands under variable or stressful conditions. Symbiotic, reef-building corals are...
Ocean acidification (OA) and nutrient enrichment threaten the persistence of near shore ecosystems, yet little is known about their combined effects on marine organisms. Here, we show that a threefold increase in nitrogen concentrations, simulating enrichment due to coastal eutrophication or consumer excretions, offset the direct negative effects o...
Turf algal assemblages are ubiquitous primary producers on coral reefs, but little is known about the response of this diverse group to ocean acidification (OA) across different temperatures. We tested the hypothesis that CO2 influences the functional response of epilithic and endolithic turf assemblages to increasing temperature. Replicate carbona...
Primary production due to photosynthesis results in daytime oxygen production across marine and freshwater ecosystems. However, a prevalent, globally-occurring nighttime spike in dissolved oxygen (DO) challenges our traditional assumption that oxygen production is limited to daylight hours, particularly in tropical coral reefs. When considered in t...
Primary production due to photosynthesis results in daytime oxygen production across marine and freshwater ecosystems. However, a prevalent, globally-occurring nighttime spike in dissolved oxygen (DO) challenges our traditional assumption that oxygen production is limited to daylight hours, particularly in tropical coral reefs. When considered in t...
Primary production due to photosynthesis results in daytime oxygen production across marine and freshwater ecosystems. However, a prevalent, globally-occurring nighttime spike in dissolved oxygen (DO) challenges our traditional assumption that oxygen production is limited to daylight hours, particularly in tropical coral reefs. When considered in t...
There are concerns about the future of coral reefs in the face of ocean acidification and warming, and although studies of
these phenomena have advanced quickly, efforts have focused on pieces of the puzzle rather than integrating them to evaluate
ecosystem-level effects. The field is now poised to begin this task, but there are information gaps th...
This paper presents a comprehensive quantitative baseline assessment of in situ net calcium carbonate accretion rates (g CaCO3 cm-2 yr-1) of early successional recruitment communities on Calcification Accretion Unit (CAU) plates deployed on coral reefs at 78 discrete sites, across 11 islands in the central and south Pacific Oceans. Accretion rates...
![Figure 1. [colour version] Daily mean ( + SE) and continuous (logged...](profile/Jennifer-Smith-76/publication/282476005/figure/fig1/AS:284256090771456@1444783341157/colour-version-Daily-mean-SE-and-continuous-logged-every-15-min-temperature-and_Q320.jpg)
Anthropogenic carbon dioxide (CO2) emissions simultaneously increase ocean temperatures and reduce ocean surface pH, a process termed ocean acidification (OA).
OA is expected to negatively affect the growth and physiology of many calcified organisms, but the response of non-calcified
(fleshy) organisms is less well understood. Rising temperatures a...
Background/Question/Methods
Ecological studies of community structure, energy flow, competitive dynamics, and nutrient subsidies are often confounded by background anthropogenic disturbances. Remote, uninhabited islands offer rare opportunities to escape such confounding factors and study fundamental ecological processes in the absence of local s...
Despite the heightened awareness of ocean acidification (OA) effects on marine organisms, few studies empirically juxtapose biological responses to CO2 manipulations across functionally distinct primary producers, particularly benthic algae. Algal responses to OA may vary because increasing CO2 has the potential to fertilize photosynthesis but impa...
Ocean acidification (OA) has important implications for the persistence of coral reef ecosystems, due to potentially negative effects on biomineralization. Many coral reefs are dynamic with respect to carbonate chemistry, and experience fluctuations in pCO2 that exceed OA projections for the near future. To understand the influence of dynamic pCO2...
Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building orga...
Despite the heightened awareness of ocean acidification (OA) effects on marine organisms, few studies empirically juxtapose biological responses to CO2 manipulations across functionally distinct primary producers, particularly benthic algae. Algal responses to OA may vary because increasing CO2 has the potential to fertilize photosynthesis but impa...
Ocean acidification (OA) has important implications for the persistence of coral reef ecosystems, due to potentially negative effects on biomineralization. Many coral reefs are dynamic with respect to carbonate chemistry, and experience fluctuations in pCO2 that exceed OA projections for the near future. To understand the influence of dynamic pCO2...
Anthropogenic CO2 emissions have exacerbated two environmental stressors, global climate warming and ocean acidification (OA), that have serious implications for marine ecosystems. Coral reefs are vulnerable to climate change yet few studies have explored the potential for interactive effects of warming temperature and OA on an important coral reef...
Projects
Project (1)
The Marine Global Earth Observatory (MarineGEO), directed by the Smithsonian’s Tennenbaum Marine Observatories Network (TMON), is the first long-term, worldwide research program to focus on understanding coastal marine life and its role in maintaining resilient ecosystems around the world
By specializing in coastal ecosystems—where marine biodiversity and people are concentrated and interact most—this initiative will provide policymakers with the science to support innovative solutions and advance management and protection of our oceans.
