Coastal Warming Research Articles

Physiological basis of interactive responses to temperature and salinity in coastal marine invertebrate: Implications for responses to warming.

Developing physiological mechanistic models to predict species’ responses to climate‐driven environmental variables remains a key endeavor in ecology. Such approaches are challenging, because they require linking physiological processes with fitness and contraction or expansion in species’ distributions. We explore those links for coastal marine species, occurring in regions of freshwater influence (ROFIs) and exposed to changes in temperature and salinity. First, we evaluated the effect of temperature on hemolymph osmolality and on the expression of genes relevant for osmoregulation in larvae of the shore crab Carcinus maenas. We then discuss and develop a hypothetical model linking osmoregulation, fitness, and species expansion/contraction toward or away from ROFIs. In C. maenas, high temperature led to a threefold increase in the capacity to osmoregulate in the first and last larval stages (i.e., those more likely to experience low salinities). This result matched the known pattern of survival for larval stages where the negative effect of low salinity on survival is mitigated at high temperatures (abbreviated as TMLS). Because gene expression levels did not change at low salinity nor at high temperatures, we hypothesize that the increase in osmoregulatory capacity (OC) at high temperature should involve post‐translational processes. Further analysis of data suggested that TMLS occurs in C. maenas larvae due to the combination of increased osmoregulation (a physiological mechanism) and a reduced developmental period (a phenological mechanisms) when exposed to high temperatures. Based on information from the literature, we propose a model for C. maenas and other coastal species showing the contribution of osmoregulation and phenological mechanisms toward changes in range distribution under coastal warming. In species where the OC increases with temperature (e.g., C. maenas larvae), osmoregulation should contribute toward expansion if temperature increases; by contrast in those species where osmoregulation is weaker at high temperature, the contribution should be toward range contraction.

Coastal Observation Using a Vertical Profiling System at the Southern Coast of Korea

At a coastal station near the southern coast of Korea, the vertical profiles of temperature salinity dissolved oxygen and velocity were obtained using a vertical profiler, Aqualog, every summer from 2016 to 2020. At the site, fishing activity was not allowed, and it was possible to maintain the profiler continuously and stably. It was set to travel every one or 2 h for two to 4 months. Thus, we were able to observe the variations of the water properties from hourly to monthly scales. The sensors were contaminated much less than we expected, and the data could be used without correction at least for our coastal applications. The main phenomena we observed are tides, coastal warming, fresh water, and responses to typhoons. On the daily time scale, the most prominent phenomenon is semi-diurnal tides, with which the thickness and temperature of coastal warm waters changed. The warm water also showed fluctuations between 10 and 15 days. The data also revealed that the tide showed strong seasonality. In summer, when the water is strongly stratified, the tidal current is baroclinic, while in winter, when the water is well mixed, the current is barotropic. Responses to typhoon induced winds were rather complicated. In one case, increase in the upper mixed layer was observed. The thick mixed layer disappeared in about a day due to advection. In another case the upper mixed layer became thinner, while the wind became stronger due the advection of the offshore water. Hydrographic observations conducted every 2 months, of course, or point measurement at a surface buoy could not show such continuous changes. More and more local fishermen are showing interest in oceanographic information, and data from the profiler could be of much use to them.

Offshore aquaculture as climate change adaptation in coastal areas: sea surface temperature trends in the Western Mediterranean Sea

The warming of the Mediterranean Sea surface is currently estimated to have been 0.4°C per decade for the period 1985-2006, and the increase in water temperature may have negatively affected marine aquaculture, e.g. by decreasing productivity. Development of aquaculture without adequate planning can lead to unsustainable economic feasibility due to future climate stressors. In this sense, offshore mariculture could be an alternative for mitigating the effect of coastal warming. The purpose of this study was to evaluate the suitability of the coastline in terms of global warming and sea surface temperature trends in locations where fish aquaculture is currently being developed, as well as the spatial changes of thermal anomalies up to 30 km from the coast, during the last 31 yr in the western Mediterranean (Spanish coast). This study was conducted using EU Copernicus Marine Service Information, covering the period 1981-2018, with a spatial resolution of 4 × 4 km. The results show that, over the last decade, the Mediterranean coastal environment off the Iberian Peninsula has experienced an increase in temperature of around 1ºC due to global change, with a clear latitudinal pattern modified by mesoscale oceanographic processes. The development of offshore aquaculture at some latitudes mitigates the extreme aestival effects on surface water temperatures. Strategic plans for aquaculture development should be able to forecast and incorporate future climate projections and local oceanographic conditions, and offshore aquaculture may provide an alternative in some regions, depending on local oceanographic conditions.

Why Do Benguela Niños Lead Atlantic Niños?

AbstractWe investigate the lag between warm interannual Sea Surface Temperature (SST) events in the eastern‐equatorial Atlantic, the Atlantic Niños, and the occurrence of Benguela Niños along the southwestern Angolan coast. While it is commonly agreed that both events are associated with equatorial and subsequent coastal‐trapped wave propagations driven remotely by a relaxation of the trade‐winds, it is surprising that SST anomalies off Angola tend to precede the ones in the eastern‐equatorial sector by ~1 month. To explain this counterintuitive behavior, our methodology is based on the experimentation with a Tropical Atlantic Ocean model. Using idealized wind‐stress perturbations from a composite analysis, we trigger warm equatorial and coastal events over a stationary and then, seasonally varying ocean mean‐state. In agreement with the linear dynamics, our results show that when the interannual wind‐stress forcing is restricted to the western‐central equatorial Atlantic, the model yields equatorial events leading the coastal ones. This implies that neither the differences in the ocean stratification between the two regions (thermocline depths or modal wave contributions) nor the seasonal phasing of the events explains the observed temporal sequence. Only if wind‐stress anomalies are also prescribed in the coastal fringe, the coastal warming precedes the eastern‐equatorial SST anomaly peak, emphasizing the role of the local forcing in the phenology of Benguela Niños. A weaker South‐Atlantic Anticyclone initiates the coastal warming before the development of eastern‐equatorial SST anomalies. Then, equatorward coastal wind anomalies, driven by a convergent anomalous circulation located on the warm Atlantic Niño, stop the remotely forced coastal warming prematurely.

Greenland surface air temperature changes from 1981 to 2019 and implications for ice‐sheet melt and mass‐balance change

AbstractWe provide an updated analysis of instrumental Greenland monthly temperature data to 2019, focusing mainly on coastal stations but also analysing ice‐sheet records from Swiss Camp and Summit. Significant summer (winter) coastal warming of ~1.7 (4.4)°C occurred from 1991–2019, but since 2001 overall temperature trends are generally flat and insignificant due to a cooling pattern over the last 6–7 years. Inland and coastal stations show broadly similar temperature trends for summer. Greenland temperature changes are more strongly correlated with Greenland Blocking than with North Atlantic Oscillation changes. In quantifying the association between Greenland coastal temperatures and Greenland Ice Sheet (GrIS) mass‐balance changes, we show a stronger link of temperatures with total mass balance rather than surface mass balance. Based on Greenland coastal temperatures and modelled mass balance for the 1972–2018 period, each 1°C of summer warming corresponds to ~(91) 116 Gt·yr−1 of GrIS (surface) mass loss and a 26 Gt·yr−1 increase in solid ice discharge. Given an estimated 4.0–6.6°C of further Greenland summer warming according to the regional model MAR projections run under CMIP6 future climate projections (SSP5‐8.5 scenario), and assuming that ice‐dynamical losses and ice sheet topography stay similar to the recent past, linear extrapolation gives a corresponding GrIS global sea‐level rise (SLR) contribution of ~10.0–12.6 cm by 2100, compared with the 8–27 cm (mean 15 cm) “likely” model projection range reported by IPCC in 2019 (SPM.B1.2). However, our estimate represents a lower limit for future GrIS change since fixed dynamical mass losses and amplified melt arising from both melt‐albedo and melt‐elevation positive feedbacks are not taken into account here.

Epiphytic benthic foraminiferal preferences for macroalgal habitats: Implications for coastal warming

Considering the thermal limits of coastal macroalgae habitats in the South-Eastern Mediterranean, it is important to study the response of the associated meiofauna to better understand the expected feedback of ecosystems to future warming. In this study, we compared benthic foraminiferal assemblages from two common macroalgal habitats, Turf and Coralline algae, based on ecological monitoring of a thermally polluted station representing near future warming, and an undisturbed environment.None of the common local species is confined to a specific algal habitat. This implies that their existence is not threatened by the disappearance of the Coralline algae. However, most likely their community structure will be impacted with coastal warming. Species that are more affiliated with Coralline algae are highly thermally tolerant, thus their proliferation might be reduced with warming. Specifically, the negative response of Coralline algae to warming may limit the contribution of invasive species such as Pararotalia calcariformata.

The Importance of Genomics for Deciphering the Invasion Success of the Seagrass Halophila stipulacea in the Changing Mediterranean Sea

The Mediterranean Sea is subject to pressures from biological invasion due to coastal anthropic activities and global warming, which potentially modify its biogeography. The Red Sea tropical seagrass Halophila stipulacea entered the Eastern Mediterranean over a century ago, and its occurrence is expanding towards the northwest. Here, we highlight the importance of genomics for deciphering the evolutionary and ecological procedures taking place during the invasion process of H. stipulacea and review the relatively sparse genetic information available for the species to date. We report the first draft whole-genome sequencing of a H. stipulacea individual from Greece, based on Illumina Sequencing technology. A comparison of the Internal Transcribed Spacer (ITS) regions revealed a high divergence of the herein sequenced individual compared to Mediterranean populations sequenced two decades ago, rendering further questions on the evolutionary processes taking place during H. stipulacea adaptation in the invaded Mediterranean Sea. Our work sets the baseline for a future analysis of the invasion genomic of the focal species.

Decadal losses of canopy-forming algae along the warm temperate coastline of Brazil.

The loss of canopy-forming seaweeds from urbanized coasts has intensified in response to warming seas and non-climatic pressures such as population growth and declining water quality. Surprisingly, there has been little information on the extent of historical losses in the South-western Atlantic, which limits our ability to place this large marine ecosystem in a global context. Here, we use meta-analysis to examine long-term (1969-2017) changes to the cover and biomass of Sargassum spp. and structurally simple algal turfs along more than 1,000 kilometres of Brazil's warm temperate coastline. Analysis revealed major declines in canopy cover that were independent of season (i.e., displaying similar trends for both summer and winter) but varied with coastal environmental setting, whereby sheltered bays experienced greater losses than coastal locations. On average, covers of Sargassum spp. declined by 2.6% per year, to show overall losses of 52% since records began (ranging from 20% to 89%). This contrasted with increases in the cover of filamentous turfs (24% over the last 27years) which are known to proliferate along human-impacted coasts. To test the relative influence of climatic versus non-climatic factors as drivers of this apparent canopy-to-turf shift, we examined how well regional warming trends (decadal changes to sea surface temperature) and local proxies of coastal urbanization (population density, thermal pollution, turbidity and nutrient inputs) were able to predict the changes in seaweed communities. Our results revealed that the most pronounced canopy losses over the past 50years were at sites exhibiting the greatest degree of coastal warming, the highest population growth and those located in semi-enclosed sheltered bays. These findings contribute knowledge on the drivers of canopy loss in the South-western Atlantic and join with global efforts to understand and mitigate declines of marine keystone species.

Stand‐Alone Eastern Pacific Coastal Warming Events

AbstractA pronounced warm anomaly occurred at the Peruvian coast in early 2017. This “Coastal Niño” caused heavy rainfalls, leading to flooding in Peru and Ecuador. At the same time, neutral conditions prevailed in the equatorial Pacific. Using observational sea surface temperature data sets and an ocean reanalysis product for the time period 1900 to 2010, previous similar events are investigated. Eighteen coastal warming events without corresponding equatorial Pacific warming are identified. Further analysis shows, however, that only four of these events are not connected to the central equatorial Pacific. All other periods of strong coastal warm anomalies are directly followed or preceded by El Niño‐like conditions. The “stand‐alone” coastal warming events are characterized by comparatively low equatorial heat content. We thus hypothesize that the depleted heat content in the equatorial Pacific in the wake of the strong 2015/2016 El Niño prevented the warming to spread westward in 2017.

Marked coastal warming off Tokai attributable to Kuroshio large meander

The Kuroshio takes a large meander (LM) path since summer of 2017 for the first time since the 2004–2005 event and is the sixth LM event since 1965. It has been commonly recognized that a cool water pool is distributed broadly in the inshore region between the Kuroshio and southern coast of the Tokai district, Japan, during the LM periods. By using the recently-developed 1-km high-resolution sea surface temperature data, here we show marked coastal warming off the Tokai district during the LM periods, despite the Kuroshio not passing through the coastal area. The archived temperature-salinity profiles reveal that large positive anomalies off the Tokai district exist not only at the sea surface but also below 300 m and the water properties of which are those of the offshore Kuroshio water. The warm, salty waters are transported inshore by the westward Kuroshio which bifurcates at around 138° E, 34° N, during the LM path periods. We detect an increased upward heat release via turbulent heat fluxes along the coastal warming region from the new-generation atmosphere reanalysis data on a 25 km grid. These are common features to the past LMs and, furthermore, the region around the Kanto-Tokai districts becomes warmer than usual in warm seasons during the LM events. Our result reveals that the LM event can exert an influence upon the Japanese climate via the coastal air-sea interaction.

North Pacific temperature and precipitation response to El Niño-like equatorial heating: sensitivity to forcing location

This study investigates the sensitivity of oceanic and atmospheric response in the extra-tropics, especially in the North Pacific, to the position of equatorial El Nino-like heating within a slab-ocean climate model. In a suite of numerical experiments, we impose an idealized equatorial sea surface temperature (SST) anomaly in the Pacific and systematically vary its longitudinal position along the equator to mimic different “flavors” of El Nino. We find that regardless of the forcing location, the induced SST pattern closely resembles a positive phase of the Pacific Decadal Oscillation with a characteristic warming along the North American coast as part of an arc-shaped pattern, accompanied by wind anomalies around the Aleutian low. However, the extent and magnitude of the coastal warming vary nonmonotonically when the forcing shifts westward along the equator. The strongest response is found when the equatorial forcing is located in the central Pacific close to the Dateline. In contrast, precipitation response over Southern California is strongest for an eastern Pacific warming centered at 150°W, even though its magnitude is highly uncertain since the boundary between dry and wet precipitation anomalies passes through this region. We repeat the experiments for cold (i.e. La Nina-like) anomalies and observe a significant asymmetry in the SST and atmospheric response between the warm and cold cases. Finally, our experiments suggest that tropical heating (or cooling) over the Western Pacific warm pool generates the largest tropical rainfall response and hence the largest global-mean SST anomaly.

Coupled ocean-atmosphere dynamics of the 2017 extreme coastal El Ni\xf1o

In March 2017, sea surface temperatures off Peru rose above 28 °C, causing torrential rains that affected the lives of millions of people. This coastal warming is highly unusual in that it took place with a weak La Niña state. Observations and ocean model experiments show that the downwelling Kelvin waves caused by strong westerly wind events over the equatorial Pacific, together with anomalous northerly coastal winds, are important. Atmospheric model experiments further show the anomalous coastal winds are forced by the coastal warming. Taken together, these results indicate a positive feedback off Peru between the coastal warming, atmospheric deep convection, and the coastal winds. These coupled processes provide predictability. Indeed, initialized on as early as 1 February 2017, seasonal prediction models captured the extreme rainfall event. Climate model projections indicate that the frequency of extreme coastal El Niño will increase under global warming.

Coastal warming and wind-driven upwelling: A global analysis

Long-term sea surface temperature (SST) warming trends are far from being homogeneous, especially when coastal and ocean locations are compared. Using data from NOAA's AVHRR OISST, we have analyzed sea surface temperature trends over the period 1982–2015 at around 3500 worldwide coastal points and their oceanic counterparts with a spatial resolution of 0.25 arc-degrees. Significant warming was observed at most locations although with important differences between oceanic and coastal points. This is especially patent for upwelling regions, where 92% of the coastal locations showed lower warming trends than at neighboring ocean locations. This result strongly suggests that upwelling has the potential to buffer the effects of global warming nearshore, with wide oceanographic, climatic, and biogeographic implications.

Vibrio vulnificus: new insights into a deadly opportunistic pathogen.

Vibrio vulnificus is a Gram-negative aquatic bacterium first isolated by the United States (US) Centers for Disease Control and Prevention (CDC) in 1964. This bacterium is part of the normal microbiota of estuarine waters and occurs in high numbers in molluscan shellfish around the world, particularly in warmer months. Infections in humans are derived from consumption of seafood produce and from water exposure. Vibrio vulnificus is a striking and enigmatic human pathogen, yet many aspects related to its biology, genomics, virulence capabilities and epidemiology remain elusive and poorly understood. This pathogen is responsible for over 95% of seafood-related deaths in the United States, and carries the highest fatality rate of any food-borne pathogen. Indeed, infections associated with this pathogen that progress to primary septicaemia have a similar case fatality rate to category BSL 3 and 4 pathogens, such as anthrax, bubonic plague, Ebola and Marburg fever. Interestingly, V. vulnificus infections disproportionately affect males (∼85% of cases) and older patients (>40 years), especially those with underlying conditions such as liver diseases, diabetes and immune disorders. New insights from molecular studies and comparative genomic approaches have offered tantalising insights into this pathogen. A recent increase and geographical spread in reported infections, in particular wound cases, underlines the growing international importance of V. vulnificus, particularly in the context of coastal warming. We outline and explore here a range of current data gaps regarding this important pathogen, and provide some current thoughts on approaches to elucidate key aspects associated with this bacterium.

Genomic Variation and Evolution of Vibrio parahaemolyticus ST36 over the Course of a Transcontinental Epidemic Expansion.

ABSTRACTVibrio parahaemolyticus is the leading cause of seafood-related infections with illnesses undergoing a geographic expansion. In this process of expansion, the most fundamental change has been the transition from infections caused by local strains to the surge of pandemic clonal types. Pandemic clone sequence type 3 (ST3) was the only example of transcontinental spreading until 2012, when ST36 was detected outside the region where it is endemic in the U.S. Pacific Northwest causing infections along the U.S. northeast coast and Spain. Here, we used genome-wide analyses to reconstruct the evolutionary history of the V. parahaemolyticus ST36 clone over the course of its geographic expansion during the previous 25 years. The origin of this lineage was estimated to be in ~1985. By 1995, a new variant emerged in the region and quickly replaced the old clone, which has not been detected since 2000. The new Pacific Northwest (PNW) lineage was responsible for the first cases associated with this clone outside the Pacific Northwest region. After several introductions into the northeast coast, the new PNW clone differentiated into a highly dynamic group that continues to cause illness on the northeast coast of the United States. Surprisingly, the strains detected in Europe in 2012 diverged from this ancestral group around 2000 and have conserved genetic features present only in the old PNW lineage. Recombination was identified as the major driver of diversification, with some preliminary observations suggesting a trend toward a more specialized lifestyle, which may represent a critical element in the expansion of epidemics under scenarios of coastal warming.

Half a century of coastal temperature records reveal complex warming trends in western boundary currents

Accelerated warming of western boundary currents due to the strengthening of subtropical gyres has had cascading effects on coastal ecosystems and is widely expected to result in further tropicalization of temperate regions. Predicting how species and ecosystems will respond requires a better understanding of the variability in ocean warming in complex boundary current regions. Using three ≥50 year temperature records we demonstrate high variability in the magnitude and seasonality of warming in the Southwest Pacific boundary current region. The greatest rate of warming was evident off eastern Tasmania (0.20 °C decade−1), followed by southern New Zealand (0.10 °C decade−1), while there was no evidence of annual warming in northeastern New Zealand. This regional variability in coastal warming was also evident in the satellite record and is consistent with expected changes in regional-scale circulation resulting from increased wind stress curl in the South Pacific subtropical gyre. Warming trends over the satellite era (1982–2016) were considerably greater than the longer-term trends, highlighting the importance of long-term temperature records in understanding climate change in coastal regions. Our findings demonstrate the spatial and temporal complexity of warming patterns in boundary current regions and challenge widespread expectations of tropicalization in temperate regions under future climate change.

The origins of the anomalous warming in the California coastal ocean and San Francisco Bay during 2014–2016

AbstractDuring 2014 exceptionally warm water temperatures developed across a wide area off the California coast and within San Francisco Bay (SFB) and persisted into 2016. Observations and numerical model output are used to document this warming and determine its origins. The coastal warming was mostly confined to the upper 100 m of the ocean and was manifested strongly in the two leading modes of upper ocean (0–100 m) temperature variability in the extratropical eastern Pacific. Observations suggest that the coastal warming in 2014 propagated into nearshore regions from the west while later indicating a warming influence that propagated from south to north into the region associated with the 2015–2016 El Niño event. An analysis of the upper ocean (0–100 m) heat budget in a Regional Ocean Modeling System (ROMS) simulation confirmed this scenario. The results from a set of sensitivity runs with the model in which the lateral boundary conditions varied supported the conclusions drawn from the heat budget analysis. Concerning the warming in the SFB, an examination of the observations and the heat budget in an unstructured‐grid numerical model simulation suggested that the warming during the second half of 2014 and early 2016 originated in the adjacent California coastal ocean and propagated through the Golden Gate into the Bay. The finding that the coastal and Bay warming are due to the relatively slow propagation of signals from remote sources raises the possibility that such warming events may be predictable many months or even several seasons in advance.

Education for Climate Change Adaptation and Resilience

Education for Climate Change Adaptation and Resilience

Smaller size‐at‐age menhaden with coastal warming and fishing intensity

The size‐at‐age of one million Brevoortia tyrannus and B. patronus, harvested from Maine to Texas over 65 years, were analysed to determine if there was evidence of changes consistent with the well documented temperature size rules. The average annual weight and length for age 3‐, 4‐ and 5‐year‐old fish declined on both the Atlantic and Gulf of Mexico (GOM) coasts. For example, the average size of a 4‐year‐old fish captured in 2010 from the Atlantic and GOM, relative to an average 4‐year‐old fish captured in 1987, is 15 per cent and 11 per cent lighter, respectively. Small changes in the year‐to‐year size of same‐aged fish were closely related to variations in the annual air temperature (used as a proxy for water temperature) for fish on both coasts. The size‐at‐age of GOM fish are also smaller during overfished periods compared with underfished periods by 10–24 per cent, and decrease by about the same proportion as indicated by temperature changes. The most plausible explanation for these size changes is that they are a consequence of recent coastal and oceanic warming. These reductions in size‐at‐age by temperature and fishing pressure affect egg production, oil yield and prey community for one‐half of the US Atlantic and GOM fish harvest. The future of menhaden fish size‐at‐age will be, it seems, smaller as oceanic temperatures rise.

Under Pressure: Climate Change, Upwelling, and Eastern Boundary Upwelling Ecosystems

The IPCC AR5 provided an overview of the likely effects of climate change on Eastern Boundary Upwelling Systems (EBUS), stimulating increased interest in research examining the issue. We use these recent studies to develop a new synthesis describing climate change impacts on EBUS. We find that model and observational data suggest coastal upwelling-favorable in poleward portions of EBUS have intensified and will continue to do so in the future. Although evidence is weak in data that are presently available, future projections show that this pattern might be driven by changes in the positioning of the oceanic high-pressure systems rather than by deepening of the continental low-pressure systems, as previously proposed. There is low confidence regarding the future effects of climate change on coastal temperatures and biogeochemistry due to uncertainty in the countervailing responses to increasing upwelling and coastal warming, the latter of which could increase thermal stratification and render upwelling less effective in lifting nutrient-rich deep waters into the photic zone. Although predictions of ecosystem responses are uncertain, EBUS experience considerable natural variability and may be inherently resilient. However, multi-trophic level, end-to-end (i.e., winds to whales) studies are needed to resolve the resilience of EBUS to climate change, especially their response to long-term trends or extremes that exceed pre-industrial ranges.