Average Sea Surface Temperature Research Articles

Fluctuations in the abundance of chub mackerel in relation to climatic/oceanic regime shifts in the northwest Pacific Ocean since the 1970s

Abstract Chub mackerel (Scomber japonicus) in the northwest Pacific Ocean is generally divided into the Tsushima Warm Current (TWC) and Pacific stocks, based on habitat and migratory patterns. Since the 1970s, the abundance of the Pacific stock has undergone more extreme fluctuations than the TWC stock, which decreased sharply in the late 1970s and remained at low levels until it began to recover after the 2000s. In this study we focused on the Pacific stock, and analysed the variability in its abundance based on time series data for catch, biomass and recruitment. Sea surface temperature is considered as a major environmental factor that affects the wintering and spawning of chub mackerel. Consequently, we used wintering and spawning ground indices, including the average sea surface temperature (SST), the meridional positional deviance of the 15 °C (MPD15) and 18 °C (MPD18) isotherms and the SST-suitability weighted size of the potential spawning ground (WSSG) in Kuroshio Current waters to analyse the impacts of oceanic environmental conditions in the wintering and spawning grounds on variations in chub mackerel abundance. The wintering and spawning ground indices showed clear decadal variability, with abrupt changes in the late 1970s, the late 1980s and the 2010s. These were correlated with major fluctuations in the abundance of chub mackerel. A combination of correlation and gradient forest analyses showed that the thermal environment in the wintering ground were relatively important predictors of chub mackerel abundance; these predictors (with a 1- or 2-year time lag) may better explain the variations in abundance after the 1970s. Variations in the SST and MPD18 during the spawning period correlated well with the recovery of chub mackerel abundance after the 2000s. Both the Asian Monsoon Index and Southern Oscillation Index correlated with the wintering and spawning ground temperature conditions, indicating that large scale climatic factors have a major influence on variability in temperature in the wintering and spawning grounds of chub mackerel. We conclude that wintering and spawning ground indices for the Kuroshio Current region may be useful for explaining the variations in chub mackerel abundance.

Reconstruction of the Persian Gulf SST variability over the last five millennia

Sea surface temperature (SST) variation in the Persian Gulf (PG) is investigated based on Mg/Ca ratio measured in the planktonic foraminifera Globigerina bulloides tests from a sediment core spanning the past 5000 years recovered from west of the Strait of Hormoz. The Mg/Ca SST data indicate a 3 °C fluctuation range with an overall temperature increase trend since the mid-Holocene. The average SST of the PG in the intervals of 5–4.2, 4.2–3, 3–1.8, 1.8–1 and 1 cal kyr BP to present, was 26.1, 26.8, 25.8, 26.3 and 26.7 °C, respectively. SST increase trend in the PG is attributed to seasonally opposing insolation changes led to northern hemisphere extra-tropics cooling and tropics warming. The short spells of decreased (increased) SST indicate a high correlation with an increase (decrease) in terrigenous silt deposited in the PG, representing humid (dry) climate conditions in the Middle East. Likely, northward migration of the Inter-tropical convergence zone during the warmer episodes of the mid to late Holocene results in a change to a drier climatic regime in S Iran. Although Arabian Sea SST has a considerable role in SST variations in the PG, however, SST of this landlocked water body is mainly controlled by a continental climate.

Temperature but not ocean acidification affects energy metabolism and enzyme activities in the blue mussel, Mytilus edulis.

In mosaic marine habitats, such as intertidal zones, ocean acidification (OA) is exacerbated by high variability of pH, temperature, and biological CO2 production. The nonlinear interactions among these drivers can be context‐specific and their effect on organisms in these habitats remains largely unknown, warranting further investigation.We were particularly interested in Mytilus edulis (the blue mussel) from intertidal zones of the Gulf of Maine (GOM), USA, for this study. GOM is a hot spot of global climate change (average sea surface temperature (SST) increasing by >0.2°C/year) with >60% decline in mussel population over the past 40 years.Here, we utilize bioenergetic underpinnings to identify limits of stress tolerance in M. edulis from GOM exposed to warming and OA. We have measured whole‐organism oxygen consumption rates and metabolic biomarkers in mussels exposed to control and elevated temperatures (10 vs. 15°C, respectively) and current and moderately elevated P CO2 levels (~400 vs. 800 µatm, respectively).Our study demonstrates that adult M. edulis from GOM are metabolically resilient to the moderate OA scenario but responsive to warming as seen in changes in metabolic rate, energy reserves (total lipids), metabolite profiles (glucose and osmolyte dimethyl amine), and enzyme activities (carbonic anhydrase and calcium ATPase).Our results are in agreement with recent literature that OA scenarios for the next 100–300 years do not affect this species, possibly as a consequence of maintaining its in vivo acid‐base balance.

Sea Surface Temperature (SST) analysis during ElNiño-LaNiña in the Java Sea

El Niño-La Niña effected climate conditions in Indonesia. The purpose of this study was to analyze the SST during El Niño-La Niña. The data used is the ENSO index SST Niño 3.4 anomaly in 1986-2017 and also SST data in the year of the El Niño-La Niña event with weak, moderate, and strong. It found that SST tended to be higher during El Niño than its normal average in the Java Sea by 29°C, while the normal SST is 28.94°C. La Niña SST in the Java Sea has an average of 29.06°C which is 0,6°C warmer than its normal average temperature. It can be concluded that El Niño-La Niña conditions do not greatly affect SST in the Java Sea. SST tends to be warmer during El Niño-La Niña than its normal average in the Java Sea. The average of SST is lower/cooler at 109.5-110.5° East Longitude than that of at the other longitudes. This is due to the mixing current of the cold water mass flow from the South China Sea with the mass of water from the Makassar Strait, each of which carries nutrients.

Genetic structure of Turbinaria peltata in the northern South China Sea suggest insufficient genetic adaptability of relatively high-latitude scleractinian corals to environment stress

With the rapid degradation of coral reefs due to global warming and anthropogenic impacts, relatively high-latitude areas, such as the northern South China Sea (SCS), are likely to become refuges for tropical coral species. Here we investigated the genetic features and adaptability of one dominant scleractinian coral species, Turbinaria peltata, in the northern SCS. A total of 81 samples from 5 sites were studied to explore potential mechanisms of adaptability to environmental stress as a result of climate change. Ten microsatellite markers developed in this study, one nuclear gene (internal transcribed spacer, ITS), and one mitochondrial gene (mitochondrial cytochrome oxidase subunit I gene, mtDNA COI) were used. Our results indicated that the genetic diversity of T. peltata in the northern SCS is low (Ar = 1.403–2.011, Ho = 0.105–0.248, He = 0.187–0.421) with the lowest in Dongfang population (DF) (Ar = 1.403, Ho = 0.22, He = 0.187). These results indicate that T. peltata has insufficient genetic adaptability and may unable to handle increasingly complex global changes. A significantly moderate genetic differentiation was observed among T. peltata populations (ΦST = 0.167), in addition to a high genetic differentiation between DF and other populations (FST = 0.272–0.536 > 0.25). The DF population near a fishing port was exposed to severe anthropogenic environmental stress, which may drive the extraordinarily high genetic differentiation between DF and other populations. Furthermore, the Mantel test results showed that the genetic differentiation of the other four populations was strongly correlated with the average sea surface temperature (SST) (R2 = 0.82, Mantel test P < 0.05) and geographical distance (R2 = 0.57, Mantel test P < 0.05). Our results suggest that the genetic structure of T. peltata in the relatively high-latitude of the SCS was significantly affected by average SST, geographical isolation, and anthropogenic activities. These findings provide a theoretical foundation for the protection of relatively high-latitude coral reefs.

Sea surface temperature prediction model based on long and short-term memory neural network

In response to the monitoring and forecasting of El Nino/La Nina phenomenon, This paper proposes a sea surface temperature prediction method based on long and short-term memory neural network for the average sea surface temperature in the NINO comprehensive area. This method uses the monthly anomaly sea surface temperature sequence for the mean sea surface temperature in the NINO Comprehensive area as the input of the long- and short-term memory neural network to establish a forecast model. The average sea surface temperature of the NINO comprehensive area is forecasted for the next 1 to 3 months. The results show that the method can better predict the average sea surface temperature of the NINO comprehensive area, which is useful for the monitoring and forecasting of El Nino/La Nina phenomenon. Provides a new approach.

A Rapid Cooling Event Over the Western Pacific Region During the Middle Bronze Age

AbstractClimate change in the mid‐to‐late Holocene transition is very important for predicting future climate trends and understanding the relationship between abrupt climate change and the development of past human civilization. In this study, Sr/Ca ratios and δ18O records with the annual resolution extracted from four fossil corals that were growing during the Middle Bronze Age Cold Epoch (MBACE) were used to reconstruct sea surface temperature (SST) and seawater δ18O (δ18Osw) in the South China Sea (SCS) during the mid‐to‐late Holocene transition. The results indicate that the SCS experienced a rapid cooling and wetting event during the period of ∼3,500–3,800 years BP (before present year 1950). Specifically, the average SST and δ18Osw declined rapidly by ∼3°C and ∼0.65‰, respectively, over an interval of ∼100 years from ∼3,850 years BP to ∼3,750 years BP. This rapid climate change pattern recorded in coral archives broadly agrees with those in foraminiferal and stalagmite records from adjacent land and ocean areas. Consistent with other records from the North Atlantic, this cold event in the Asia‐Western Pacific region that occurred during the MBACE and was originally identified in the North Atlantic and European regions should have occurred at the global scale, which might be caused by changes in the Asian summer monsoon linked with solar irradiance and/or the North Atlantic climate. In addition, this rapid climate change might support the occurrence and timing of the outburst flood event during the Xia Dynasty and might have led to the fall of the Xia Dynasty.

Detection of SST Fronts from a High-Resolution Model and Its Preliminary Results in the South China Sea

AbstractA frontal detection algorithm is developed with the capability of detecting significant frontal segments of sea surface temperature (SST) in the high-resolution South China Sea Operational Forecasting System (SCSOFS). To effectively obtain frontal information, a gradient-based Canny edge detection algorithm is improved with postprocessing designed for high-resolution numerical models, aiming at extracting primary ocean fronts while ensuring the balance of frontal continuity and positioning accuracy. Metrics of frontal probability and strength are used to measure the robustness of the results in terms of mean state and seasonal variability of frontal activities in the South China Sea (SCS). Most fronts are found in the nearshore and form a strip shape extending from the Taiwan Strait to the coast of Vietnam. The SCSOFS is found to reproduce strong seasonal signals dominating the variability of the frontal strength and occurrence probability in the SCS. We implement the algorithm on the daily averaged SST derived from two other SST analyses for intercomparison in the SCS.

Long term changes in life history traits and catches of the round sardinella, Sardinella aurita (Clupeidae), along the Senegal coast, West Africa

The main life history traits of the round sardinella, Sardinella aurita Valenciennes 1847 were updated in Senegalese coastal waters, together with an evaluation of the captures over the last 33 years (1981–2013). In the context of global change and an increase in the average sea surface temperature along the Senegalese coast, most of the life history traits of S. aurita, such as condition factor, period of reproduction, egg sizes, relative fecundity and growth did not change significantly over the years. In contrast, the size at first sexual maturity and the absolute fecundity increased significantly, and current catches recorded less large individuals. The growth was rapid and very variable, with a longevity estimated at 6–7 years.These updated data for life history traits show that the round sardinella was fully exploited in the area, that the fishing effort for this species should be reduced, and that the minimum size (120 mm) authorized by the Senegalese fisheries code should be increased (185–200 mm) to maintain stocks along the Senegal coast.

Insights into coral growth rate trends in Fiji

Colonies of the massive coral species, Porites lutea, located at six shallow reefs across Fiji, were cored and analysed to create a chronological growth rate record. Boosted regression tree models were used to investigate relationships between annual coral growth rates and corresponding environmental variables. An ecologically based prediction model was then created to determine expected coral growth distribution across shallow reefs in Fiji for the year 2019. Annual average growth rates for the Porites lutea colonies at coral reefs in Savusavu, Leleuvia, and Navakavu reflected typical values for the Porites genus in the Indo-Pacific. Conversely, annual average growth rates at Suva Harbour, Dennis Patch, and the Coral Coast were on the lower spectrum for the Indo-Pacific Porites genus. Porites lutea growth rates were significantly influenced by latitude, whereby growth rates decreased with increasing gradient away from the equator. Growth rates were highest in the 1940s and 1950s but declined from the 1960s onwards, with significant declines observed in more polluted sites. Growth rates in Fiji are influenced by a combination of site-specific water quality and annual average sea surface temperature, with secondary contributions from the colony’s distance to shore, chlorophyll concentration, and meteorological events such as tropical cyclones, storms, and ENSO events. Predicted coral growth distribution showed that lowest growth rates are predicted around the southern and south-eastern coast of Viti Levu, highlighting the need for better marine protection at these highly populated coastlines.

Where are the North Atlantic fish going, and where should fishermen go?

On September 23, 2019, the World Meteorological Organization WMO published the Global Climate Report 2015-2019, which explained the trend of global warming. The phenomenon of rising global ocean temperature in the report is also an issue that needs to be researched. It will make certain marine life be forced to migrate from their habitats, thus affecting the development of economic industries such as fisheries. As consultants to the Scottish North Atlantic Fisheries Management Association, in this work, we have launched a corresponding study on this issue. Corresponding mathematical models have been established, which can well predict the future distribution of fish populations. Questions are essentially predictions of the future distribution of North Atlantic fish stocks and their impact on fishing companies. So our first task is to build an identification and prediction model of future fish habitat space model (IPM-FFHS Model). Because this distribution is caused by changes in ocean temperature, we have established a prediction model for the average sea surface temperature of the North Atlantic region (AMO-BP Model) based on BP neural network to predict future SST. At the same time, other influential factors of the distribution can modify the model. The AMO-BP Model was then combined with the current distribution of the habitat of the fish to draw a predicted spatial image of the future habitat range. At last, we combined the IPM-FFHS Model to obtain the abandonment temperature threshold of the fishery to obtain the duration of fish migration and the survival environment under different effects.

A modelled global distribution of the kelp biome

Kelp, seaweeds of the order Laminariales, are of ecological and conservation importance because they form undersea forest habitat for many varieties of fauna and flora including mammals, and commercial fish species. In the absence of a world map of the kelp biome, we predicted its potential distribution using geographic records and environment variables in a MaxEnt model. This estimated that the kelp biome occupied 1,469,900 km2 and was present on 22% of the world's coastline. While average sea surface temperature was the most important environmental variable for the biome across all species, wave height, distance from the coast and minimum temperature were of most importance for individual species. This map can be used in planning where marine reserves should be best located, modelling the effects of climate change, and in estimating the blue (ocean) carbon storage. Current field observations should confirm the presence of kelp within the modelled biome, and if absent consider if human impacts, including climate change, are to blame.

Patterns and drivers of understory macroalgal assemblage structure within subtidal kelp forests

Kelp species are found along ~ 25% of the world’s coastlines, where they provide myriad of ecological goods and services. However, compared with many other terrestrial and marine vegetated ecosystems, kelp forests have been critically understudied in many regions, leading to pressing knowledge gaps that hinder management and conservation efforts. We conducted a large-scale survey of understorey macroalgae within subtidal kelp forests dominated by Laminaria hyperborea at 12 sites, nested within 4 regions in the United Kingdom (UK). Regions spanned ~ 9° in latitude and encompassed a gradient in average sea surface temperature of ~ 2.5 °C. We employed a combination of traditional hand-harvesting of quadrat samples and a novel 3D photogrammetry technique to quantify crustose coralline algae. The structure of understorey macroalgal assemblages was highly variable but showed clear partitioning at the spatial scales of both regions and sites. At the regional-scale, we observed a general increase in richness, diversity and biomass from north to south, most likely due to biogeographical context, ocean climate and the structure and composition of overlying kelp canopies. Site level variation was most likely driven by concurrent variability in wave exposure and kelp canopy structure. Our study shows that understorey macroalgal assemblages represent a rich and abundant component of kelp forests in the northeast Atlantic, with high biodiversity value that warrant conservation measures. As these kelp forest ecosystems are structured by multiple physical and biological processes, current and predicted environmental change will likely alter the diversity and composition of understorey macroalgal assemblages.

Summer season sea surface temperature changes in the Aegean Sea based on 30years (1989-2019) of Landsat thermal infrared data.

In this research, sea surface temperature (SST) variability for the summer season in the Aegean Sea was analysed over a period of 30years by using the Landsat thermal infrared bands. A total of 88 Landsat 5, 7, and 8 thermal infrared satellite images from June, July, and August were used for each year from 1989 to 2019. To estimate SST from the thermal infrared band data, thermal infrared sensor at-sensor spectral radiance, and thermal infrared sensor top-of-atmosphere brightness temperatures were used. SST pixel values were extracted from thermal images for the 3-month summer season of each year. In order to validate the findings, regression analysis was performed between the Mediterranean Sea Ultra High Resolution SST L4 data and Landsat data for the 2008-2019 period. Regression constant R-squared values were found to be 0.9672 for June, 0.9550 for July, 0.9634 for August, and 0.9634 for all summer seasons. It was calculated that the minimum value of the average SST was 18.44 ± 2.87°C in 1992, and the maximum value of the average SST was 23.45 ± 0.70°C in 2018. According to the Landsat data, over the past 30years, the annual average SST changes were estimated to be 0.11°C, and the total changes of average SST were estimated to be 3.19 ± 1.26°C. As a result of the analysis and the validation, we can see that there is a rising trend in sea surface temperature in the Aegean Sea. However, it is difficult to determine whether this upward trend is related to global climate change.

Effect of Acute Seawater Temperature Increase on the Survival of a Fish Ectoparasite

Extreme warming events that contribute to mass coral bleaching are occurring with increasing regularity, raising questions about their effect on coral reef ecological interactions. However, the effects of such events on parasite-host interactions are largely ignored. Gnathiid isopods are common, highly mobile, external parasites of coral reef fishes, that feed on blood during the juvenile stage. They have direct and indirect impacts on their fish hosts, and are the major food source for cleaner fishes. However, how these interactions might be impacted by increased temperatures is unknown. We examined the effects of acute temperature increases, similar to those observed during mass bleaching events, on survivorship of gnathiid isopod juveniles. Laboratory experiments were conducted using individuals from one species (Gnathia aureamaculosa) from the Great Barrier Reef (GBR), and multiple unknown species from the central Philippines. Fed and unfed GBR gnathiids were held in temperature treatments of 29 °C to 32 °C and fed Philippines gnathiids were held at 28 °C to 36 °C. Gnathiids from both locations showed rapid mortality when held in temperatures 2 °C to 3 °C above average seasonal sea surface temperature (32 °C). This suggests environmental changes in temperature can influence gnathiid survival, which could have significant ecological consequences for host-parasite-cleaner fish interactions during increased temperature events.

Sedimentary response to sea level and climate changes in the inner sea of Maldives carbonate platform over the past 30 kyr

We applied AMS 14C dates, Mg/Ca estimated sea surface temperature (SST), planktonic foraminiferal abundance, coarse component and X-ray diffraction mineral composition analyses for an International Ocean Discovery Program (IODP) sediment Hole U1467C in the Maldives inner sea, to reveal factors that affected the depositional process in the Maldives inner sea over the past 30 kyr. We found that the linear sedimentation rate (LSR) in Holocene (6.8 cm/kyr) was obviously higher than that in glacial period (3.45 cm/kyr); the average SST during the Holocene was 2–3°C higher than that in glacial stage. High abundance of planktonic foraminifera occurred during the glacial period, which was consistent with the variation of pelagic biogenic component. Reef-sourced material showed apparent high percentage during the Holocene (43.5%), in contrast to the low values during the glacial stage (20.7%). Terrigenous matter, only accounting for a small percentage in carbonate platform, was relatively high during the glacial period than that in the Holocene. We therefore conclude that reef-sourced material, dominated in the glacial-interglacial sediment sources, was mainly affected by sea level and climate changes. During glacial stage, sea level low-stand and weakened weathering in Maldives limited the input of the eroded material into the inner sea, resulting in low LSR; while the Holocene high sea level accompanied with rapid growth of the reef atoll and enhanced weathering, brought more reef-sourced material to the inner sea, leading to increased LSR and lowered abundance of planktonic foraminifera. The sea level and climate-controlled reef-sourced material changes are the key to understand the sedimentary process of the Maldives inner sea. Our study will shed some light on the evolution of glacial-interglacial sedimentary process of carbonate platform.

Re-evaluating mid-Holocene reef “turn-off” on the inshore Southern Great Barrier Reef

In the face of changing global climate the future of corals reefs is uncertain. High latitude reefs may offer potential refugia for corals under projected increasing sea surface temperatures (SSTs). To understand the reef growth potential of modern high latitude reefs it is first necessary to understand past reef growth and response to climatic and environmental changes. The history of the Great Barrier Reef (GBR) has been shown to be punctuated by a multi-millennial Mid-Holocene reef “turn-off” or initiation hiatus in the Northern and Southern GBR (∼5500–2500 years before present [yr. BP]). Here we present the results of chronologically constrained reef matrix cores from five continental island fringing reefs and coral communities in the Keppel Islands to revaluate the timing, extent and possible drivers of the Mid-Holocene hiatus in the Southern GBR. Earliest initiation occurred at Wedge and Halfway Islands at 7773 ± 19 yr. BP and 7455 ± 20 yr. BP, respectively. Following initiation, vertical reef accretion at Halfway was comparable to previously reported rates for the GBR of ∼3.4 mm yr−1, increasing to ∼8.0 mm yr−1 between 6100 and 5500 yr. BP. Conversely, the coral community at Wedge Island, located closer to mainland terrestrial influence, accreted <1.0 mm yr−1 to 5500 yr. BP after which a 3000-year stratigraphic hiatus is observed. A negative relative sea level oscillation at 5500 yr. BP coincides with the transition of Halfway reef from vertical accretion to lateral progradation and the “turn-off” of the Wedge Island coral community. The reef at Middle Island appears to have initiated in the midst of the Mid-Holocene hiatus period at ∼3500 yr. BP, with vertical accretion at both Middle and Halfway Islands being the highest for the region’s history at 12.5 ± 3.3 mm yr−1 and 15.0 ± 6.0 mm yr−1, respectively, between 3500 and 3000 yr. BP. A proposed late-Holocene relative sea level highstand of ∼1 m at ∼2000 yr. BP coincides with the first dates identified at near-shore Divided Island, and the re-initiation of coral growth at Wedge Island, although both showed limited net vertical accretion. These near-shore sites “turned-off” again between 1300 and 900 yr. BP, likely associated with a rapid relative sea level fall. Reef progradation also slowed at Halfway Island and Middle Island after 1200 yr. BP until a recent increase in reef growth at Middle Island since the late 1970’s associated with modern increases in average SSTs. Our data suggests that although reef-scale “turn-off” events occurred, there is no evidence for a regional scale hiatus in coral growth or initiation comparable to that found further north on the GBR. A comparison with other Southern and south-Central GBR reef cores suggests that relative sea level oscillations in conjunction with changes to climate, appear to have driven varying, but synchronous, modifications to reefs at 5500, 4600, 2800 and 1200 yr. BP.

Kecenderungan Naiknya Suhu Permukaan Laut dan Resiliensi Karang Setelah Kejadian Pemutihan Karang 2010 dan 2016 di Taman Wisata Perairan (TWP) Pulau Pieh, Padang, Sumatra Barat

&lt;strong&gt;Trend of Sea Surface Temperature Increase and Coral Resilience After Bleaching Events of 2010 and 2016 in The Marine Tourism Park (TWP) of Pieh Island, Padang, West Sumatra&lt;/strong&gt;. The coral bleaching event has hit almost all of Indonesia's waters at least 4 times (in the last 34 years), which the last two events (2010 and 2016) have been discussed rather deeply. However, detailed studies in a specific location, such as in Marine Tourism Park (TWP) of Pieh Island, Padang waters, West Sumatra Province that influenced by the water mass of Indian Ocean have not yet been studied. The aim of this paper is to examine the trend of sea surface temperatures (SST)’s increase in the TWP of Pieh Island in 2010 and 2016 coral bleaching, and the coral resilience after the events. In this study, the long-term SST data acquired from the Aqua MODIS satellite images were used intensively. Results show that the highest mean monthly SST called MMM that corals can be tolerated in the TWP of Pieh is 29.6 &lt;sup&gt;o&lt;/sup&gt;C, higher than in all Indonesian waters (29.1 &lt;sup&gt;o&lt;/sup&gt;C).The differences between the anomaly SST and the normal SST (MMM) or called Hot Spot (HS) has exceeded the average MMM in the 2010 bleaching event around 0.4-0.5 &lt;sup&gt;o&lt;/sup&gt;C with its peak in April, and with alert-1 severity (Degree Heating Weeks (DHW) &amp;lt; 8 &lt;sup&gt;o&lt;/sup&gt;C-weeks; which means that the coral has partial bleaching with patchy pattern).In 2016, the HS increased by an average of 0.5 ~ 1.0 &lt;sup&gt;o&lt;/sup&gt;C with peaks in January-February and May-June and with the severity of Alert-2 (DHW ≥ 8 &lt;sup&gt;o&lt;/sup&gt;C-weeks, which means corals experienced severe bleaching, over wider areas, and some of corals are died). One year earlier (2015), higher HS with an average value of 0.3-0.8 &lt;sup&gt;o&lt;/sup&gt;C and DHW ~ 4 &lt;sup&gt;o&lt;/sup&gt;C-weeks were also observed. This indicates that coral bleaching events in the TWP of Pieh Island is repeated and occurs for long periods.The trend of increasing SST in this TWP is 0.23&lt;sup&gt;o&lt;/sup&gt;C/decade, lower than in the all Indonesian waters (0.36 &lt;sup&gt;o&lt;/sup&gt;C/decade). This trend shows that coral reefs in Indonesian waters including this TWP have a high resilience to recover themselves from bleaching, since the trend of increasing SST &amp;lt; 1.0 &lt;sup&gt;o&lt;/sup&gt;C/decade of the 11 coral resilience key factors, positive factors that support high coral resilience are low pollution/nutrients, low sedimentation (high water transparency), and low unfriendly of human activities, while the most negative one is the explosion of crown-of-thorns starfish, Acanthaster planci population as well as coral disease.

Spatial and interannual variability of presettlement tropical fish assemblages explained by remote sensing oceanic conditions

Understanding the interannual effect of various environmental factors on biodiversity distribution is fundamental for developing biological monitoring tools. The interannual variability of environmental factors on presettlement fish assemblages (PFAs) has been so far under investigated, especially in Madagascar. Numerous explanatory variables including local hydro-dynamic conditions recorded during the sampling night, characteristics of the benthic substrate and remotely sensed oceanic conditions (RSOC) were used to explain the spatio-temporal variability of PFAs in southwestern Madagascar. Gradient forest analyses were used to hierarchically classify the effect of these explanatory variables on the PFAs for two sites and during two different recruitment seasons. RSOC variables appeared to better explain the PFAs than the local variable and the characteristics of the benthic substrate. The PFAs caught in water masses with coastal characteristics were better explained than those with open water characteristics. This spatial variability is hypothesised to be linked to differences in feeding conditions among water masses. The gradient forest analyses also highlighted the complexity of predicting PFAs as the species for which abundances were better explained by RSOC variables varied between years. This interannual variability was mainly explained by the interannual variation of chlorophyll a (Chl a) concentration, wind and surface current, with better prediction obtained during the year with high Chl a values associated with high averaged sea surface temperature. These findings suggest the importance of forecasting Chl a concentrations, taking into account the impact of tropical storms and climate variability in order to predict PFAs in the future.

Reconstructing Pliocene West Pacific Warm Pool Hydroclimate Using In Situ Microanalyses on Fossil Planktic Foraminifer Shells

AbstractA controversial aspect of Pliocene (5.3–2.6 Ma) climate is whether El Niño‐like (El Padre) conditions, characterized by a reduced trans‐equatorial sea‐surface temperature (SST) gradient, prevailed across the Pacific. Evidence for El Padre is chiefly based on reconstructions of sea‐surface conditions derived from the oxygen isotope (δ18O) and Mg/Ca compositions of shells belonging to the planktic foraminifer Trilobatus sacculifer. However, fossil shells of this species are a mixture of multiple carbonate phases—pre‐gametogenic, gametogenic (reproductive), and diagenetic calcites—that formed under different physiological and/or environmental conditions and are averaged in conventional whole‐shell analyses. Through in situ measurements of micrometer‐scale domains within Pliocene‐aged shells of T. sacculifer from Ocean Drilling Program Site 806 in the western equatorial Pacific, we show that the δ18O of gametogenic calcite is 0.6–0.8‰ higher than pre‐gametogenic calcite, while the Mg/Ca ratios of these two phases are the same. Both the whole‐shell and pre‐gametogenic Mg/Ca records indicate that average early Pliocene SSTs were ~1°C warmer than modern, with present‐day SSTs being established during the latest Pliocene and early Pleistocene (~3.0–2.0 Ma). The measurement of multiple calcite phases by whole‐shell δ18O analyses masks a late Pliocene to earliest Pleistocene (3.6–2.2 Ma) decrease in seawater δ18O (δ18Osw) values reconstructed from in situ pre‐gametogenic δ18O and Mg/Ca measurements. Our novel δ18Osw record indicates that sea‐surface salinities in the west Pacific warm pool were higher than modern prior to ~3.5 Ma, which is consistent with more arid conditions under an El Padre state.