Rising Sea Surface Temperatures Research Articles

Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching.

The disruption of the coral-algae symbiosis (coral bleaching) due to rising sea surface temperatures has become an unprecedented global threat to coral reefs. Despite decades of research, our ability to manage mass bleaching events remains hampered by an incomplete mechanistic understanding of the processes involved. In this study, we induced a coral bleaching phenotype in the absence of heat and light stress by adding sugars. The sugar addition resulted in coral symbiotic breakdown accompanied by a fourfold increase of coral-associated microbial nitrogen fixation. Concomitantly, increased N:P ratios by the coral host and algal symbionts suggest excess availability of nitrogen and a disruption of the nitrogen limitation within the coral holobiont. As nitrogen fixation is similarly stimulated in ocean warming scenarios, here we propose a refined coral bleaching model integrating the cascading effects of stimulated microbial nitrogen fixation. This model highlights the putative role of nitrogen-fixing microbes in coral holobiont functioning and breakdown.

Changes in Holocene meridional circulation and poleward Atlantic flow: the Bay of Biscay as a nodal point

Abstract. This paper documents the evolution over the last 10 kyr of one of the key parameters of climate: sea-surface temperatures (SSTs) in the North Atlantic. We focus on the southern Bay of Biscay, a highly sensitive oceanographic area regarding the dynamics of the North Atlantic subpolar and subtropical gyres (SPG and STG respectively). This site furthermore offers unique sedimentary environments characterized by exceptional accumulation rates, enabling the study of Holocene archives at (infra)centennial scales. Our results mainly derive from planktonic foraminiferal association analysis on two cores from the southern Landes Plateau. These associations are used as the basis of modern analogue technique transfer functions to track past hydrographical changes. SST reconstructions were thus obtained at an exceptional resolution and compared to a compilation of Holocene records from the northeastern North Atlantic. From this regional perspective are shown fundamental timing differences between the gyre dynamics, nuancing classical views of a simple meridional overturning cell. Our study highlights that western Europe underwent significant oscillations of (annual) SST during the last 10 kyr. During well-known intervals of mild boreal climate, warm shifts of more than 3 °C per century are accurately concomitant with positive sea-surface temperature anomalies and rise of micropalaeontological indicators of gyre dynamics in the northern North Atlantic, pointing to periods of greater intensity of the North Atlantic Current (SPG cell especially). Conversely, the SST signal records short-term cold anomalies which could be related to weaker SPG dynamics.

Functional and energetic consequences of climate change on a predatory whelk

The increasing rise in sea surface temperature caused by human activities currently represents the major threat to biodiversity and natural food webs. In this study we used the Lessepsian mussel Brachidontes pharaonis, one of the most recent invaders of the Mediterranean Sea, as a model to investigate the effect of a novel prey and a chronic increase in temperatures on functional parameters of local consumers, compared to the native mytilid species Mytilaster minimus. In particular we focused on the whelk Stramonita haemastoma, a widespread Mediterranean intertidal predator that actively preys on bivalves, barnacles and limpets, by studying the direct effects of such multiple stressors on feeding and growth rate, projected into a future climate change scenario (RCP8.5) relative to 2046–2065 with higher hypothesized temperatures of 2 °C. Gastropods showed a significantly higher feeding rate (ADFR) on M. minimus at high (6.45 ± 0.43) vs low temperatures (5.15 ± 0.33) compared to B. pharaonis (2.84 ± 0.37 vs 2.48 ± 0.27). Ingestion rate (ADIR), however, recorded higher values for B. pharaonis at high (1.71 ± 0.22) and low (1.49 ± 0.16) temperatures, compared to M. minimus (0.17 ± 0.01 vs 0.14 ± 0.01). Prey significantly influenced growth rate, condition index and the length-weight relationship (LWR) of whelks, while only ADFR seemed to be influenced by higher temperatures. In conclusion the extra amount of energy from the novel prey, together with temperature side effects, successfully influenced growth rates and reproductive events, positively affecting the global fitness of whelks.

Risk assessment and uncertainty of the shrimp trawl fishery in the Gulf of California considering environmental variability

The shrimp fishery off the Mexican Pacific coast is the country's most important fishery from the economic standpoint. However, it faces serious problems, including the fleet’s overcapitalization and age, in addition to the environmental variability that affects the size of catches. Thus, this activity depends on a variety of factors that add uncertainty to the profitability of fishing vessels. This study aims to estimate the probability of success and economic risk of "type vessels" under two different environmental variability scenarios in the Gulf of California. The results from the economic simulation pointed to the vessel type used in Guaymas (Sonora) as the most efficient one under a neutral climate change scenario, showing a homogeneous behaviour in physical characteristics and mode of operation. By contrast, under a scenario of a monotonic rise in sea surface temperature, the shrimp fishery faces a greater risk of incurring economic losses. The simulated climate behaviour scenarios revealed that the activity involves a moderate economic profitability under the neutral scenario; however, under the warming scenario, profitability may be low or even nil due to the risks and uncertainty resulting from the influence of environmental phenomena.

Premonsoon Drought in India Observed from Space

Abstract Satellite observations between 2007 and 2015 are used to characterize the annual occurrence of the premonsoon drought (PMD), which causes human death and economic hardship in India, and to postulate its scientific causes. The PMD is identified as the driest and hottest weeks in central India just before the summer monsoon onset. The onset is marked by a sharp increase in precipitation and soil moisture and a decrease in air temperature. The difference between integrated moisture transported in from the Arabian Sea and out to the Bay of Bengal is largely deposited as rain over land during the summer monsoon. The PMD occurs during the short period when moisture is drawn out to the Bay of Bengal before it can be replenished from the Arabian Sea. The time gap is caused by the earlier start of summer monsoon (southwest) winds in the Bay of Bengal than in the Arabian Sea. Sea surface temperature rise precedes the start of summer monsoon wind in both the Arabian Sea and the Bay of Bengal, and it has the potential to give advance warning of the PMD and thus allow mitigation of the adverse effects.

Seasonal and Inter Annual Variation of Sea Surface Temperature in the Indonesian Waters

Sea surface temperature plays an important role in air-sea interactions. This research was conducted to understand seasonal and interannual variations of sea surface temperature in the Indonesian waters. The data used in this research was daily sea surface temperature in 1986 to 2015 which was obtained from the Physical Oceanography Distributed Active Archive Center - National Aeronautics and Space Administration. Method used in this study was the anomaly analysis. The result showed that the seasonal and interannual variations of sea surface temperature in the Indonesian waters varied. Seasonal variations of SST in the Makasar Strait, Sulawesi Sea, and Halmahera Sea were low. High seasonal variations of sea surface temperature occurred in the southern waters of Java, Timor Sea, Arafura Sea, and Banda Sea, which were allegedly due to the upwelling process. In addition, interannual variation of sea surface temperature in the Indonesian waters fluctuated. From 1986 to 2000, it showed a negative anomaly dominant. Meanwhile, from 2001 to 2015, it showed a positive anomaly dominant. The effect of Indian Ocean Dipole on the fluctuation of sea surface temperature in the Indonesian waters was stronger than ENSO. Within the last 30 years, the sea surface temperature in the Indonesian water indicated a rising trend. The highest sea surface temperature rise occurred in the Halmahera Sea that reached 0.66 OC/30 years and the lowest was in the Timor Sea of 0.36 OC/30 years.

The influence of winter and summer atmospheric circulation on the variability of temperature and sea ice around Greenland

Most peripheral seas of the Arctic Ocean have seen a pronounced rise in sea surface temperatures in the past century, and this signature of Arctic amplification in proximity to the land suggests that the observed marine and terrestrial changes might be connected to each other. Using in situ observations of temperature from nine coastal meteorological stations around Greenland (GrSTs) and remotely sensed fields of sea ice extent (SIE), we examine the interannual variations of surface air temperature (T2m) and sea level pressure (SLP) anomalies associated with the GrSTs and SIEs surrounding Greenland, specifically within Baffin Bay, the Greenland Sea and Kara-Barents Seas. During winter, the interannual variation in T2m and SLP of the west and south coasts of GrSTs and the Baffin Bay SIE are different from that of the east coast of GrSTs and the SIEs in the Greenland Sea and Kara-Barents Seas. The GrSTs on the west and south coasts of Greenland and the Baffin Bay SIE are associated with the T2m anomalies over Baffin Bay and Davis Strait. The winter SLP patterns associated with these GrSTs and SIEs show positive anomalies over the Arctic and negative anomalies over the North Atlantic with a large-scale atmospheric circulation such as the winter NAO. On the contrary, the east coast of GrSTs and the SIEs in the Greenland Sea and Kara-Barents Seas are correlated with the T2m anomalies over the Greenland Sea and Barents Sea. The surface wind pattern associated with the SIEs in the Greenland Sea and Kara-Barents Seas has a cyclonic circulation in the Greenland Sea and Barents Sea. At the local scale the cyclonic circulation could induce negative SIE anomalies and contribute to increasing open water in the Greenland Sea and Barents Sea. The effect of the loss of sea ice and the heat from the open ocean warming to the atmosphere may influence the GrSTs in the east coast of Greenland. As a result, the T2m pattern associated with the GrSTs in the east coast of Greenland is similar to the pattern of the SIEs in the Greenland Sea and Kara-Barents Seas. During summer, the T2m anomalies associated with all GrSTs and SIEs have positive anomalies over mid-latitudes. The two times series of all GrSTs and SIEs fluctuate quickly and display large trends towards warming temperatures and decreasing SIE. The summer SLP associated with all GrSTs and SIEs are characterised by a seesaw pattern between positive anomalies over the Arctic and negative anomalies over mid-latitudes. The summer SLP anomalies are similar to the summer AO pattern, and it is noteworthy that the summer anticyclonic circulation over the Arctic and Greenland has contributed to the variability and trends in both summer GrSTs and SIEs.

Reproductive synchrony in a diverse Acropora assemblage, Vamizi Island, Mozambique

AbstractMulti‐specific synchronous spawning has never been documented for East Africa, but coral spawn‐slicks are observed annually around Vamizi Island, Northern Mozambique. We monitored gamete development in Acropora species from July 2012 to October 2013 and from August to September 2014 to describe patterns of reproductive seasonality and synchrony within and amongst species of Acropora. Gamete maturation was highly synchronized within and amongst Acropora species and culminated in multi‐specific spawning events lasting 1–3 nights in each year of the study, in late August or September. In 2013 and 2014, 50% or more of the colonies of over 50% of the species sampled prior to the spawning events had mature gametes. In all years, 91–99% colonies sampled after the spawning events had no visible gametes. The percentage of colonies with mature gametes was up to 100% for some species. In other species, the absence of mature gametes throughout the study period indicates that they might not spawn in certain years. The analysis of a 8‐year record of observations of spawn‐slicks showed that spawning generally occurred once a year for a few consecutive days between September and December, during periods of rising sea surface temperature and low wind speed and rainfall. This study is the first to quantitatively document coral reproduction in Mozambique and multi‐specific synchronous spawning off the coast of Africa. These findings contrast with the asynchronous breeding reported for Kenyan reefs and support the absence of breakdown in coral reproductive synchrony towards low latitudes.

Antagonistic Effects of Ocean Acidification and Rising Sea Surface Temperature on the Dissolution of Coral Reef Carbonate Sediments

Increasing atmospheric CO2 is raising sea surface temperature (SST) and increasing seawater CO2 concentrations, resulting in a lower oceanic pH (ocean acidification; OA), which is expected to reduce the accretion of coral reef ecosystems. Although sediments comprise most of the calcium carbonate (CaCO3) within coral reefs, no in situ studies have looked at the combined effects of increased SST and OA on the dissolution of coral reef CaCO3 sediments. In situ benthic chamber incubations were used to measure dissolution rates in permeable CaCO3 sands under future OA and SST scenarios in a coral reef lagoon on Australia’s Great Barrier Reef (Heron Island). End of century (2100) simulations (temperature +2.7°C and pH -0.3) shifted carbonate sediments from net precipitating to net dissolving. Warming increased the rate of benthic respiration (R) by 29% per 1°C and lowered the ratio of productivity to respiration (P/R; ΔP/R = -0.23), which increased the rate of CaCO3 sediment dissolution (average net increase of 18.9 mmol CaCO3 m-2 d-1 for business as usual scenarios). This is most likely due to the influence of warming on benthic P/R which, in turn, was an important control on sediment dissolution through the respiratory production of CO2. The effect of increasing CO2 on CaCO3 sediment dissolution (average net increase of 6.5 mmol CaCO3 m-2 d-1 for business as usual scenarios) was significantly less than the effect of warming. However, the combined effect of increasing both SST and pCO2 on CaCO3 sediment dissolution was non-additive (average net increase of 5.6 mmol CaCO3 m-2 d-1) due to the different responses of the benthic community. This study highlights that benthic biogeochemical processes such as metabolism and associated CaCO3 sediment dissolution respond rapidly to changes in SST and OA, and that the response to multiple environmental changes are not necessarily additive.

Quorum Sensing in Marine Microbial Environments.

Quorum sensing (QS) is a form of chemical communication used by certain bacteria that regulates a wide range of biogeochemically important bacterial behaviors. Although QS was first observed in a marine bacterium nearly four decades ago, only in the past decade has there been a rise in interest in the role that QS plays in the ocean. It has become clear that QS, regulated by signals such as acylated homoserine lactones (AHLs) or furanosyl-borate diesters [autoinducer-2 (AI-2) molecules], is involved in important processes within the marine carbon cycle, in the health of coral reef ecosystems, and in trophic interactions between a range of eukaryotes and their bacterial associates. The most well-studied QS systems in the ocean occur in surface-attached (biofilm) communities and rely on AHL signaling. AHL-QS is highly sensitive to the chemical and biological makeup of the environment and may respond to anthropogenic change, including ocean acidification and rising sea surface temperatures.

Distribution of Dall's Porpoise, Phocoenoides dalli, in the North Pacific and Bering Sea, Based on T/S Oshoro Maru 2012 Summer Cruise Data.

Dall's porpoise (Phocoenoides dalli) is a small toothed cetacean, widely inhabiting the North Pacific Ocean and adjacent seas, between about 30 and 62°N; however, only limited studies of its ecology have been made in nearshore areas. A cetacean sighting survey lasting 60 days was conducted during the 2012 summer cruise of the T/S Oshoro Maru (Hokkaido University, Japan) in the North Pacific Ocean and Bering Sea. Based on this data, the distribution of Dall's porpoises and the factors controlling it in the pelagic habitat were investigated. A total of 808 individual Dall's porpoises in 166 groups were sighted during a total of 469.6 hr and 4946.6 nm observations. The cruise consisted of three legs and the average porpoise group size was significantly larger in Leg 1. The sightings were concentrated at water depths of less than 1000 m and near eastern Aleutian passes. Sighting clusters were found on the 200 m isobath of the southeastern Bering Sea continental slope. There was a peak in sightings where the sea surface temperature (SST) was relatively cold, between 5 and 7°C. Although similar track routes were taken in Leg 1 and Leg 3, the number of sightings per unit effort was larger in Leg 1. This difference may have arisen from the significant rise in SST as the season progressed. Relatively large group size found in this study might relate with prey abundance along the Aleutian Islands.

Uncertainty in climate projections for the 21st century northwest European shelf seas

There are a number of sources of uncertainty that impact climate projections for regional seas. We have assessed the impact that uncertain large-scale climate forcings have on the projections for the north-west European shelf seas. An ensemble of global Atmosphere-Ocean climate model (GCM) projections made by perturbed (atmospheric) parameter model variants which were designed to span uncertainty in climate sensitivity, was dynamically downscaled with the shelf seas model POLCOMS. The simulations were run as transient experiments (from 1952 to 2098) under a medium emissions scenario (SRES A1B). This study has focused on centennial changes over the period 2069–2098 relative to 1960–1989, but also refers to the full transient simulation to assess the significance of projected changes given interannual and low-frequency variability. The ensemble mean of the POLCOMS projections showed a shelf and annual mean Sea Surface Temperature (SST) rise of 2.90°C (±2σ=0.82°C), and a Sea Surface Salinity (SSS) freshening of −0.41psu (±2σ=0.47psu) between these periods. We described the spread in a field for a particular period using the variances associated with both the time mean ensemble dispersion (ensemble variance) and with the interannual variability. For SST in the present-day period, the magnitudes of both ensemble and interannual variance were fairly spatially homogenous. While the future interannual variance is of similar magnitude to that of the present day, the ensemble variance increased considerably into the future period. For SSS, both sources of variance were more spatially heterogeneous, and both increased into the future period. We investigated relationships between the projected shelf seas changes across the ensemble and changes in the large-scale climate forcing. We found that the near surface-air temperature from the driving GCM (averaged over the domain) and the GCM surface salinity to the west of the POLCOMS domain are good proxies for the changes within the shelf seas. We then compared these GCM indicators of shelf changes in our ensemble (under A1B) to the same measures across a number of CMIP5 models, under the RCP6.0 and RCP8.5 scenarios. The spread of these indicators, for our ensemble, fall within the range of the CMIP5 models (particularly under RCP8.5), suggesting our shelf projections would be consistent with an ensemble of projections driven by CMIP5 models.

Detection of thermal pollution from power plants on China’s eastern coast using remote sensing data

The acceleration of the industrialization process in China has increased the demand for electricity and triggered a power-plant building boom, especially along China’s eastern coast, where the economy gets off early and enjoys a fast development. The thermal plumes, residual chlorine, nuclides and other pollutions produced by the thermal and nuclear power plants have exerted an impact on the coastal eco-environment. To monitor the thermal pollution from the power plants at Yueqing Bay on the eastern coast, in this research, the distribution of sea surface temperature (SST) surrounding the power plants is obtained by using the SST retrieval methods developed for Landsat Enhanced Thematic Mapper Plus (ETM+), HJ-1B infrared sensor (IRS) and Terra moderate resolution imaging spectroradiometer (MODIS) data. The comparison of the SST retrieval results before and after the operation of power plants indicates that the total area of sea waters that is impacted by the thermal discharge from the two power plants at Yueqing Bay is approximately 17.95 km2, with the highest SST rise of 4.5 °C appearing over the waters around the outlet of the Huaneng Yuhuan power plant on the eastern shore, whereas the highest SST rise around the Zheneng Yueqing power plant on the western shore reaches 3.8 °C. The intensity and scope of influence of the thermal discharge mainly depend on the installed capacity of power plants, coastal terrain, and tide. Although the area where the SST rise is more than 3 °C is not large, thermal discharge still has an impact on bay ecosystems due to the relatively closed nature of the bay environment. Due to the influence of rising water temperatures on the reproduction and individual evolution of fish, shrimp, crabs, shellfish and other aquatic creatures, in the long term, the thermal pollution from coastal power plants will affect the volume of natural fishery and biological resources throughout the waters. The quantitative retrieval results also suggest that relative to MODIS data, Landsat ETM+ and HJ-1B IRS data with a high spatial resolution are more applicable to the estimation of small-scale SST, and IRS data with a high temporal resolution are more helpful in the study of spatio-temporal variability of thermal plumes from coastal power plants.

Transient turbid water mass reduces temperature-induced coral bleaching and mortality in Barbados.

Global warming is seen as one of the greatest threats to the world’s coral reefs and, with the continued rise in sea surface temperature predicted into the future, there is a great need for further understanding of how to prevent and address the damaging impacts. This is particularly so for countries whose economies depend heavily on healthy reefs, such as those of the eastern Caribbean. Here, we compare the severity of bleaching and mortality for five dominant coral species at six representative reef sites in Barbados during the two most significant warm-water events ever recorded in the eastern Caribbean, i.e., 2005 and 2010, and describe prevailing island-scale sea water conditions during both events. In so doing, we demonstrate that coral bleaching and subsequent mortality were considerably lower in 2010 than in 2005 for all species, irrespective of site, even though the anomalously warm water temperature profiles were very similar between years. We also show that during the 2010 event, Barbados was engulfed by a transient dark green turbid water mass of riverine origin coming from South America. We suggest that reduced exposure to high solar radiation associated with this transient water mass was the primary contributing factor to the lower bleaching and mortality observed in all corals. We conclude that monitoring these episodic mesoscale oceanographic features might improve risk assessments of southeastern Caribbean reefs to warm-water events in the future.

Response of marine copepods to a changing tropical environment: winners, losers and implications

Background. Climate change concurrent with anthropogenic disturbances can initiate serial changes that reverberate up the food chain with repercussions for fisheries. To date, there is no information available concerning the combined effects of global warming and human impacts on tropical marine food webs. While temperate copepods respond differently to warming and environmental stressors, the extent to which tropical copepods can adapt to rising temperature of already warm waters remains unknown. We hypothesize that sea warming and other anthropogenic disturbances over the long term will have the greatest impact on the copepod community in nearshore waters where their effects are accentuated, and therefore vulnerable and resilient species could be identified.Methods. Zooplankton samples were collected during two time periods (1985–86 and 2014–15) interposed by marked anthropogenic disturbances, and at the same five stations located progressively from inshore to offshore in Klang Strait, Malaysia, following the asymmetrical before-after-control-impact (BACI) design. Copepods were identified to species, and results were interpreted by univariate (ANOVA) and multivariate (PERMANOVA, PCO) analyses of the computed species abundance and diversity measures.Results. Copepod total abundance was not significantly different among stations but higher after disturbance than before disturbance. However, changes in the abundance of particular species and the community structure between time periods were dramatic. Coastal large-bodied calanoid species (e.g., Acartia spinicauda, Calanopia thompsoni, Pseudodiaptomus bowmani and Tortanus forcipatus) were the most vulnerable group to disturbance. This however favored the opportunistic species (e.g., Oithona simplex, O. attenuata, Hemicyclops sp., Pseudomacrochiron sp. and Microsetella norvegica). Small-bodied copepods (e.g., Paracalanus sp., Parvocalanus crassirostris and Euterpina acutifrons) were unaffected. Centropages tenuiremis was likely an introduced species. There was no significant loss in species richness of copepods despite the dramatic changes in community structure.Discussion. Sea warming and other human-induced effects such as eutrophication, acidification and coastal habitat degradation are likely the main factors that have altered copepod community structure. The large-bodied estuarine and coastal calanoid copepods are surmised to be vulnerable to eutrophication and hypoxia, while both resilient and opportunistic species are largely unaffected by, or adaptable to, degraded coastal environments and observed sea surface temperature (SST) rise. It is forecasted that SST rise with unmitigated anthropogenic impacts will further reduce large-bodied copepod species the favoured food for fish larvae with dire consequences for coastal fish production.

Role of Indian Ocean SST variability on the recent global warming hiatus

Previous studies have shown a slowdown in the warming rate of the annual mean global surface temperature in the recent decade and it is referred to as the hiatus in global warming. Some recent studies have suggested that the hiatus in global warming is possibly due to strong cooling in the tropical Pacific. This study investigates the possible role of the Indian Ocean warming on the tropical Pacific cooling. Despite the continued rise in sea surface temperature (SST) over the tropical Indian Ocean, SST over the tropical Pacific has shown a cooling trend in the recent decade (2002−2012). It is well known fact that the Indian Ocean and the Pacific Ocean are strongly coupled to each other and the Indian Ocean basin wide warming is triggered by El Niño on interannual time scale. However, in the recent decade, this relationship is weakening. The recent Indian Ocean warming is triggering a Matsuno-Gill type response in the atmosphere by generating anomalous cyclonic circulations on either side of equator over the tropical Indian Ocean and anomalous easterlies along the tropical Pacific Ocean. These anomalous easterlies result in Ekman divergence in the equatorial Pacific and produce upwelling Kelvin waves, cools the tropical Pacific and therefore indirectly contributes to the hiatus in global warming.

REGIONAL ECONOMIC IMPACTS OF CLIMATE CHANGE: A COMPUTABLE GENERAL EQUILIBRIUM ANALYSIS FOR AN ALASKA FISHERY

AbstractWe compute the effects on the Alaska economy of reduced pollock harvests from rising sea surface temperature using a regional dynamic computable general equilibrium model coupled with a stochastic stock‐yield projection model for eastern Bering Sea walleye pollock. We show that the effects of decreased pollock harvest are offset to some extent by increased pollock price, and that fuel costs and the world demand for the fish, as well as the reduced supply of the fish from rising sea surface temperature, are also important factors that determine the economic and welfare effects.

Sudden and extreme hyperthermals, low-oxygen, and sediment influx drove community phase shifts following the end-Permian mass extinction

We present a correlated record of carbon isotope geochemistry and sedimentological analysis for the Lower Triassic Werfen Formation from the Italian Dolomites. Macro- and mid-sized fossil diversity, ecology, and climate sensitivity are included to provide an integrated account of the benthic response to paleoenvironmental change. Novel communities developed in the wake of the mass extinction during pervasive fluctuations in environmental conditions. In the sedimentary sequences of the Werfen Formation of the Italian Dolomites, microbialites, microconchids, foraminifera, and ubiquitous flat-clams, formed a complex community within the first 500,000years. Later, increased sea-surface temperatures and inundation of the seafloor with siliciclastic sediments favored infaunal bivalves and microgastropods. Persistent trends in the environment can produce directional, often irreversible, community shifts defined here as phase shifts. Phase shifts in ecosystem structure can be driven by environmental shifts across threshold boundaries to produce an “abrupt and dramatic” novel community composition, a phenomenon readily observed during the Early Triassic. Previously described “disaster forms” including flat clams, microconchids, foraminifera, and microbialites are re-envisioned as a phase shift community. We hypothesize that the unique, persistent, and reoccurring microbialite and mid-sized fauna assemblages observed during the initial recovery from the end-Permian mass extinction and re-appearing throughout the Early Triassic typify a phase shift community. In the Smithian, infaunal bivalves and microgastropods represent a second phase shift community developed in response to a persistent, directional rise in sea-surface temperatures and enhanced sediment influx. We compare and contrast phase shifts with other models for ecosystem recovery including trophic, competition, and Earth System Succession.

Sixteen-year phytoplankton biomass trends in the northwestern Pacific Ocean observed by the SeaWiFS and MODIS ocean color sensors

Using multisensor/platform biophysical data collected from 1997 to 2013, we investigated trends of the concentrations of phytoplankton biomass (Chl) in the northwestern Pacific Ocean (NWPO) and the probable responsible factors. The trend of rising sea surface temperature (SST) was the main factor maintaining phytoplankton positive net growth and resulted in a trend of increasing Chl at high latitudes in all seasons. At latitudes of 36–46°N, east of 160°E, the trend of rising SST was accompanied by a trend of declining Chl, markedly in spring and fall, which could be ascribed to strengthened stratification. The trends of environmental variables in the Oyashio area have modified conditions in a way detrimental to phytoplankton growth, the result being a trend of declining Chl from spring to fall. Chl south of roughly 36°N exhibited different trends in different seasons because of the different trends of vertical stratification. Whereas the observed 16-year Chl trends were not primarily influenced by interannual climate variability, to some degree they were likely modified by decadal variability associated with a weakened Aleutian Low pressure. This work prompts further comprehensive studies to investigate the probable ecological consequences of the observed Chl trend for high-trophic-level marine organisms in the NWPO.

“Super-quenching” state protects Symbiodinium from thermal stress — Implications for coral bleaching

The global rise in sea surface temperatures causes regular exposure of corals to high temperature and high light stress, leading to worldwide disastrous coral bleaching events (loss of symbiotic dinoflagellates (Symbiodinium) from reef-building corals). Our picosecond chlorophyll fluorescence experiments on cultured Symbiodinium clade C cells exposed to coral bleaching conditions uncovered the transformations of the alga's photosynthetic apparatus (PSA) that activate an extremely efficient non-photochemical “super-quenching” mechanism. The mechanism is associated with a transition from an initially heterogeneous photosystem II (PSII) pool to a homogeneous “spillover” pool, where nearly all excitation energy is transferred to photosystem I (PSI). There, the inherently higher stability of PSI and high quenching efficiency of P700+ allow dumping of PSII excess excitation energy into heat, resulting in almost complete cessation of photosynthetic electron transport (PET). This potentially reversible “super-quenching” mechanism protects the PSA against destruction at the cost of a loss of photosynthetic activity. We suggest that the inhibition of PET and the consequent inhibition of organic carbon production (e.g. sugars) in the symbiotic Symbiodinium provide a trigger for the symbiont expulsion, i.e. bleaching.