Annual cycle of primary production in the Cariaco Basin: Response to upwelling and implications for vertical export

Muller‐Karger, Frank E.; Varela, Ramón; Thunell, Robert C.; Scranton, Mary I.; Bohrer, Richard; Taylor, Gordon; Capelo, Juan; Astor, Yrene; Tappa, Eric; Ho, Tung‐Yuan; Walsh, John J.

doi:10.1029/1999jc000291

Cited by 157 publications

(128 citation statements)

References 64 publications

Supporting

Mentioning

123

Contrasting

Order By: Relevance

“…1). These zonal winds relax for the remainder of the year, although minor wind-driven secondary upwelling events can occur in July to August (9).The December to May upwelling supports ∼70% of annual NPP (Fig. S1 A and B).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Ecosystem responses in the southern Caribbean Sea to global climate change

Taylor

Muller‐Karger

Thunell

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

109

View full text Add to dashboard Cite

Over the last few decades, rising greenhouse gas emissions have promoted poleward expansion of the large-scale atmospheric Hadley circulation that dominates the Tropics, thereby affecting behavior of the Intertropical Convergence Zone (ITCZ) and North Atlantic Oscillation (NAO). Expression of these changes in tropical marine ecosystems is poorly understood because of sparse observational datasets. We link contemporary ecological changes in the southern Caribbean Sea to global climate change indices. Monthly observations from the CARIACO Ocean Time-Series between 1996 and 2010 document significant decadal scale trends, including a net sea surface temperature (SST) rise of ∼1.0 ± 0.14°C (±SE), intensified stratification, reduced delivery of upwelled nutrients to surface waters, and diminished phytoplankton bloom intensities evident as overall declines in chlorophyll a concentrations (ΔChla = −2.8 ± 0.5%·y −1 ) and net primary production (ΔNPP = −1.5 ± 0.3%·y −1 ). Additionally, phytoplankton taxon dominance shifted from diatoms, dinoflagellates, and coccolithophorids to smaller taxa after 2004, whereas mesozooplankton biomass increased and commercial landings of planktivorous sardines collapsed. Collectively, our results reveal an ecological state change in this planktonic system. The weakening trend in Trade Winds (−1.9 ± 0.3%·y −1 ) and dependent local variables are largely explained by trends in two climatic indices, namely the northward migration of the Azores High pressure center (descending branch of Hadley cell) by 1.12 ± 0.42°N latitude and the northeasterly progression of the ITCZ Atlantic centroid (ascending branch of Hadley cell), the March position of which shifted by about 800 km between 1996 and 2009. ecosystem state change | oceanography | plankton productivity P hytoplankton support over 95% of marine food webs and are responsible for about half of the Earth's conversion of CO 2 to biomass through net primary production (NPP) (1). Long-term declines in phytoplankton biomass and production in over 70% of the global ocean have been inferred recently from satellite imagery and century-long shipboard records of water clarity (2, 3). These reports of large-scale changes are at odds with trends directly observed at specific locations within the same ocean domains.

show abstract

Section: Resultsmentioning

confidence: 99%

“…S1 A and B). Most NPP occurs in the upper 60 m of the water column (9), where Chla concentrations have averaged 56 mg·m −2 during productive periods and are less than 27 mg·m −2 otherwise. NPP is usually undetectable below 80 m depth (9).…”

Section: Resultsmentioning

confidence: 99%

Ecosystem responses in the southern Caribbean Sea to global climate change

Taylor

Muller‐Karger

Thunell

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

109

View full text Add to dashboard Cite

show abstract

“…Seasonal, wind-driven upwelling events fuel strong phytoplankton blooms in the photic zone. As the organic products of these blooms sink, they are remineralized at rates comparable to those from the oxic open ocean and even higher near the chemocline (Muller-Karger et al, 2001). Nevertheless, about 10 g/m 2 /yr organic carbon escapes remineralization in the water column and is delivered to underlying sediments.…”

Section: Study Sitementioning

confidence: 99%

Rapid organic matter sulfurization in sinking particles from the Cariaco Basin water column

Raven

Sessions

Adkins

et al. 2016

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

Organic matter (OM) burial in marine sediments is a potentially important control on global climate and the long-term redox state of the earth's surface. Still, we have only a limited understanding of the processes that stabilize OM and facilitate its preservation in the geologic record. Abiotic reactions with (poly)sulfides can enhance the preservation potential of OM, but for this process to be significant it needs to compete with OM remineralization, the majority of which occurs before sinking particles reach the sea floor. Here we investigate whether OM sulfurization occurs within sinking particles in the Cariaco Basin, a modern sulfidic marine environment with high rates of OM burial.Proto-kerogen in sinking particles is frequently more sulfur-rich and 34 S-depleted than expectations for biomass, with a composition that is difficult to explain by mixing with resuspended or terrigenous material. Instead, it appears that sulfur is being incorporated into OM on a timescale of days in sinking particles. The flux of this abiogenic organic S from particles is equivalent to approximately two-thirds of the total amount of protokerogen S at 10 cm depth in underlying sediments (ODP Core 1002B); after 6000 years of more gradual sulfurization reactions, potential water column sources are still equivalent to nearly half of the total proto-kerogen S in Cariaco sediments. Water column sulfurization is most extensive during periods of upwelling and high primary productivity 2 and appears to involve elemental S, possibly via polysulfides. This process has the potential to deliver large amounts of OM to the sediments by making it less available for remineralization, generating OM-rich deposits. It represents a potentially dynamic sink in the global carbon cycle that can respond to changes in environmental conditions, including the size and intensity of O 2 -depleted environments. Water column OM sulfurization could also have played a more significant role in the carbon cycle during ocean anoxic events, for example during the Cretaceous.

show abstract

“…The MaxEnt method provides a robust estimate of the realized niche and is insensitive to the challenges posed by the detection of species at low abundance (33). During the 15 y from 1996 to 2011, there was a gradual warming of about 1°C, an increase in average irradiance, and a decrease in nitrate concentration in the upper mixed layer (0-30 m) at Station CARIACO (34). These are regional changes resulting from the movement of the Significance Most ecosystem models used to predict changes in community composition with climate change assume species' responses to environmental conditions are genetically fixed on the century scale, but this hypothesis has not been tested.…”

mentioning

confidence: 99%

Phytoplankton adapt to changing ocean environments

Irwin

Finkel

Muller‐Karger

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

126

View full text Add to dashboard Cite

Model projections indicate that climate change may dramatically restructure phytoplankton communities, with cascading consequences for marine food webs. It is currently not known whether evolutionary change is likely to be able to keep pace with the rate of climate change. For simplicity, and in the absence of evidence to the contrary, most model projections assume species have fixed environmental preferences and will not adapt to changing environmental conditions on the century scale. Using 15 y of observations from Station CARIACO (Carbon Retention in a Colored Ocean), we show that most of the dominant species from a marine phytoplankton community were able to adapt their realized niches to track average increases in water temperature and irradiance, but the majority of species exhibited a fixed niche for nitrate. We do not know the extent of this adaptive capacity, so we cannot conclude that phytoplankton will be able to adapt to the changes anticipated over the next century, but community ecosystem models can no longer assume that phytoplankton cannot adapt.phytoplankton | realized niches | climate change | evolution D uring the last several decades, global land temperature has increased by ∼0.3°C per decade (1), and a further increase in global mean air temperatures of 1.1-6.4°C is expected by 2100 (2). The warming of the oceans is resulting in spatially variable changes in sea surface temperature (3, 4), salinity, mixed-layer depth, and the distribution of nutrients. Ocean time series sampled on a monthly basis document intra-and interannual changes in physical forcing and biogeochemistry, providing crucial data for formulating ecosystem models and characterizing how ecosystems respond to climate change (5, 6). We have very high confidence that climate change during the last several decades has influenced the abundance, phenology, and geographic ranges for a wide assortment of species (7-10). Further increases in global temperature may result in significant and nonreversible changes to many populations and communities (11,12). If dispersal rates are rapid relative to the rate of evolutionary adaptation, changes in climate will result in local species being displaced by nonresident species from a regional pool of species that are better adapted to the new conditions (13). When modelers project changes in biotic communities under climate change scenarios, they generally assume that each species has a genetically determined fixed environmental niche and that species' spatial and temporal distributions will be determined by environmental conditions (14-17). A recent model of this type predicts a loss of a third of tropical phytoplankton strains by 2100 with a ∼2°C increase in mean temperature (11); however, paleoecological studies indicate organisms may be much more resilient to climate change than these types of models suggest (18,19).Local populations may be able to acclimate physiologically and then adapt through evolutionary change to gradual climate shifts. We do not know the constraints or timescales req...

show abstract

Annual cycle of primary production in the Cariaco Basin: Response to upwelling and implications for vertical export

Cited by 157 publications

References 64 publications

Ecosystem responses in the southern Caribbean Sea to global climate change

Ecosystem responses in the southern Caribbean Sea to global climate change

Rapid organic matter sulfurization in sinking particles from the Cariaco Basin water column

Phytoplankton adapt to changing ocean environments

Contact Info

Product

Resources

About