Increasing Sea Temperatures Research Articles

The potency of Sentinel-2 satellite for monitoring during and after coral bleaching events of 2016 in the some islands of Marine Recreation Park (TWP) of Pieh, West Sumatra

The coral bleaching event (CBE) which trigerred by increase in sea temperatures of 1-2˚C during El-Nino can make corals stressful or potentially dead. Many CBE research are conducted using sea temperature data measured through infrared thermal (TIR) satellite sensor. However, very few study use optical remote sensing data. This study aim to analyze the potential of optical Sentinel-2 (S-2) satellite data for monitoring during (Jun. 2016) and after (Jun. 2018) CBE in small islands of marine protected areas (TWP) of Pieh. A series image analysis procedure was conducted, i.e. simple DOS atmospheric correction; normalizating digital numbers (DN) of Blue, Green and Red bands of subject images during and after CBE to the reference image (before CBE. Dec. 2015) using “pseudo invariant feature (PIF)” approach; subtracting the DN of each bands of images during and after CBE to the reference image, and generating color composite of natural color with a contrast stretch. Result showed that this procedure can detected clearly the CBE. There was an average decreasing bleaching trend of 1.63 ha (15.8%), which indicated that some corals have recovered from thermal stress inside the TWP of Pieh. However, islands outside the TWP of Pieh, showed an increasing trend by an average of 0.50 ha (21.2%). The predation corals by the crown of thorn seastar, Acanthaster planci, whose population exploded after CBE was the main reason why CBE still detected both inside and outside the TWP of Pieh. This study shows the ability and potency of optical remote sensing data of S-2 satellite to monitor CBE, but need a lot of validation from many other sites. This result is very useful for supporting project such as COREMAP CTI.

Symposium report: Great Barrier Reef restoration symposium, 2018

Ecological Management & RestorationVolume 20, Issue 2 p. 175-178 Conference Report Symposium report: Great Barrier Reef restoration symposium, 2018 Damien W. Burrows, Damien W. BurrowsSearch for more papers by this authorJemma Purandare, Jemma PurandareSearch for more papers by this authorLine Bay, Line BaySearch for more papers by this authorNathan Cook, Nathan CookSearch for more papers by this authorDanielle Koopman, Danielle KoopmanSearch for more papers by this authorSuzanne Long, Suzanne LongSearch for more papers by this authorPetra Lundgren, Petra LundgrenSearch for more papers by this authorDavid Mead, David MeadSearch for more papers by this authorSheriden Morris, Sheriden MorrisSearch for more papers by this authorMaxine Newlands, Maxine NewlandsSearch for more papers by this authorChristian Roth, Christian RothSearch for more papers by this authorDavid Wachenfeld, David WachenfeldSearch for more papers by this authorAdam K. Smith, Adam K. SmithSearch for more papers by this authorIan M. McLeod, Ian M. McLeodSearch for more papers by this author Damien W. Burrows, Damien W. BurrowsSearch for more papers by this authorJemma Purandare, Jemma PurandareSearch for more papers by this authorLine Bay, Line BaySearch for more papers by this authorNathan Cook, Nathan CookSearch for more papers by this authorDanielle Koopman, Danielle KoopmanSearch for more papers by this authorSuzanne Long, Suzanne LongSearch for more papers by this authorPetra Lundgren, Petra LundgrenSearch for more papers by this authorDavid Mead, David MeadSearch for more papers by this authorSheriden Morris, Sheriden MorrisSearch for more papers by this authorMaxine Newlands, Maxine NewlandsSearch for more papers by this authorChristian Roth, Christian RothSearch for more papers by this authorDavid Wachenfeld, David WachenfeldSearch for more papers by this authorAdam K. Smith, Adam K. SmithSearch for more papers by this authorIan M. McLeod, Ian M. McLeodSearch for more papers by this author First published: 22 May 2019 https://doi.org/10.1111/emr.12368Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume20, Issue2May 2019Pages 175-178 RelatedInformation

A temporal shift in trophic diversity among a predator assemblage in a warming Arctic.

Climate change is leading to northward shifts in species distributions that is altering interspecific interactions at low- and mid-trophic levels. However, little attention has been focused on the effects of redistributions of species on the trophic ecology of a high trophic-level predator assemblage. Here, during a 22-year period (1990–2012) of increasing sea temperature (1.0°C) and decreasing sea ice extent (12%) in Cumberland Sound, Nunavut, Canada, we examined the trophic structure of a near-apex predator assemblage before (1990–2002) and after (2005–2012) an increase in the availability of capelin—generally an indicator species in colder marine environments for a warming climate. Stable isotopes (δ13C and δ15N) were used in a Bayesian framework to assess shifts in diet, niche size and community-wide metrics for beluga whales (Delphinapterus leucas), ringed seals (Pusa hispida), Greenland halibut (Reinhardtius hippoglossoides) and anadromous Arctic char (Salvelinus alpinus). After 2005, consumption of forage fish increased for all predator species, suggesting diet flexibility with changing abiotic and biotic conditions. An associated temporal shift from a trophically diverse to a trophically redundant predator assemblage occurred where predators now play similar trophic roles by consuming prey primarily from the pelagic energy pathway. Overall, these long-term ecological changes signify that trophic shifts of a high trophic-level predator assemblage associated with climate change have occurred in the Arctic food web.

Future scenarios of marine resources and ecosystem conditions in the Eastern Mediterranean under the impacts of fishing, alien species and sea warming

Using a temporal-dynamic calibrated Ecosim food web model, we assess the effects of future changes on marine resources and ecosystem conditions of the Israeli Mediterranean continental shelf. This region has been intensely invaded by Indo-Pacific species. The region is exposed to extreme environmental conditions, is subjected to high rates of climate change and has experienced intense fishing pressure. We test the impacts of a new set of fishing regulations currently being implemented, a continued increase in sea temperatures following IPCC projections, and a continued increase in alien species biomass. We first investigate the impacts of the stressors separately, and then we combine them to evaluate their cumulative effects. Our results show overall potential future benefits of fishing effort reductions, and detrimental impacts of increasing sea temperature and increasing biomass of alien species. Cumulative scenarios suggest that the beneficial effects of fisheries reduction may be dampened by the impact of increasing sea temperature and alien species when acting together. These results illustrate the importance of including stressors other than fisheries, such as climate change and biological invasions, in an ecosystem-based management approach. These results support the need for reducing local and regional stressors, such as fishing and biological invasions, in order to promote resilience to sea warming.

The Effect of Increased Temperature and Coral Acclimation of Sinularia dura

Coral reefs are one of the most vulnerable ecosystems in the world. With evidence of recent and notable mass coral bleaching at the Great Barrier Reef, it is imperative that coral species and their response to increased temperatures be studied in order to identify coral acclimation and the “winners” and “losers” of climate change. Sinularia dura is a commons coral species in South Asian and Southeast Asian water. This study has shown that even a 1 to 2 degrees centigrade increase in temperature can have huge effect on the health of Sinularia Dura which has implications to the status of coral reefs due to increased sea temperatures caused by climate change.

Sea surface temperature predicts the movements of an Arctic cetacean: the bowhead whale

The effects of climate change constitute a major concern in Arctic waters due to the rapid decline of sea ice, which may strongly alter the movements and habitat availability of Arctic marine mammals. We tracked 98 bowhead whales by satellite over an 11-year period (2001–2011) in Baffin Bay - West Greenland to investigate the environmental drivers (specifically sea surface temperature and sea ice) involved in bowhead whale’s movements. Movement patterns differed according to season, with aggregations of whales found at higher latitudes during spring and summer likely in response to sea-ice retreat and increasing sea temperature (SST) facilitated by the warm West Greenland Current. In contrast, the whales moved further south in response to sea temperature decrease during autumn and winter. Statistical models indicated that the whales targeted a narrow range of SSTs from −0.5 to 2 °C. Sea surface temperatures are predicted to undergo a marked increase in the Arctic, which could expose bowhead whales to both thermal stress and altered stratification and vertical transport of water masses. With such profound changes, bowhead whales may face extensive habitat loss. Our results highlight the need for closer investigation and monitoring in order to predict the extent of future distribution changes.

Trade-offs in disease and bleaching susceptibility among two color morphs of the Hawaiian reef coral, Montipora capitata

Two threats impacting coral reefs are bleaching and disease, and differential susceptibility to both exists among and within coral taxa. Bleaching resistance is commonly linked to the clade of endosymbiotic Symbiodinium, but may come at a cost to other biological traits. Montipora capitata is an Indo-Pacific reef-building coral with two color morphs, red and orange, which harbor different clades of Symbiodinium. We explored whether these color morphs displayed differences in bleaching/disease susceptibility and other biological traits (growth rate, reproductive output, and lipid content). We found a trade-off between disease and bleaching susceptibility. The orange morph had significantly higher disease prevalence, whereas the red morph had significantly higher bleaching prevalence. Thermal stress experiments found that bleaching and loss of photochemical efficiency occurred significantly faster in the red morph, but at normal temperatures, the red morph had a significantly higher growth rate. Higher abundance of the red morph in the field suggests that disease resistance is a more successful strategy in the absence of thermal stress events. The orange morph may better tolerate increases in sea temperatures, but may not persist due to decreased growth rate and increased disease susceptibility. Trade-offs in response to stressors highlight the need to consider local and global threats to coral reefs.

Multiple stressors facilitate the spread of a non‐indigenous bivalve in the Mediterranean Sea

AbstractAimThe introduction of non‐indigenous species (NIS) via man‐made corridors connecting previously disparate oceanic regions is increasing globally. However, the environmental and anthropogenic factors facilitating invasion dynamics and their interactions are still largely unknown. This study compiles and inputs available data for the NIS bivalve Brachidontes pharaonis across the invaded biogeographic range in the Mediterranean basin into a species distribution model to predict future spread under a range of marine scenarios.LocationMediterranean Sea.MethodsA systematic review produced the largest presence database ever assembled to inform the selection of biological, chemical and physical factors linked to the spread of B. pharaonis through the Suez Canal. We carried out a sensitivity analysis to simulate current and future trophic and salinity scenarios. A species distribution model was run to determine key drivers of invasion, quantify interactive impacts arising from a range of trophic states, salinity conditions and climatic scenarios and forecast future trajectories for the spread of NIS into new regions under multiple‐parameter scenarios (based on the main factors identified from the systematic review).ResultsImpacts on invasion trajectory arising from climate change and interactions with increasing salinity from the new opening of the canal were the primary drivers of expansion across the basin, the effects of which were further enhanced by eutrophication. Predictions of the current distribution were most accurate when multiple stressors were used to drive the model. A habitat suitability index developed at a subcontinental scale from model outputs identified novel favourable conditions for future colonization at specific locations under 2030 and 2050 climatic scenarios.Main conclusionsFuture expansion of B. pharaonis will be enhanced by climate‐facilitated increased sea temperature, interacting with increasing pressures from salinity and eutrophication. The spatially explicit risk output maps of invasions represent a powerful visual product for use in communication of the spread of NIS and decision‐support tools for scientists and policymakers. The suggested approach, the observed distribution pattern and driving processes can be applied to other NIS species and regions by providing novel forecasts of species occurrences under future multiple stressor scenarios and the location of suitable recipient habitats with respect to anthropogenic and environmental parameters.

Mass mortality hits gorgonian forests at Montecristo Island.

Mediterranean gorgonian forests are species-rich habitats, and like many other marine habitats they are threatened by anthropogenic disturbances and mass mortality events. These mortality events have often been linked to anomalies in the temperature profiles of the Mediterranean region. On 5 September 2017, colonies of the gorgonians Eunicella singularis and Eunicella cavolini exhibited rapid tissue loss, down to a depth of 30 m along the steep cliffs of Montecristo Island, Tuscan Archipelago National Park, Tyrrhenian Sea, Italy. Interestingly, Montecristo has previously been identified as a reference site for the ecological quality assessment of the western Mediterranean benthic assemblages on rocky bottoms. The observed mortality event occurred during a period of increased sea temperature. By utilising a combination of high-resolution oceanographic analysis, forecast models and citizen science initiatives, we propose that an early warning system for the concomitance of heat waves and mortality events can be put in place. A temperature-based coral disease surveillance tool could then be established for the entire Mediterranean Sea. Such a tool would allow for the timely study of mass mortality phenomena and the implementation of prompt mitigation and/or restoration initiatives. Finally, this specific mortality event, in a Marine Protected Area, offers a unique opportunity to monitor and assess the resilience of gorgonian populations and associated benthic assemblages in the absence of other, more directly, anthropogenic disturbances such as pollution and land runoff.

Biology of the king crab Paralomis birsteini on the continental slope off the western Antarctic Peninsula

Predatory king crabs (Lithodidae) structure benthic communities in their native habitats and cause shifts in the composition of benthic assemblages when introduced to new environments. Cold temperatures have apparently excluded skeleton-breaking predators from the continental shelf around Antarctica for millions of years, but recent increases in sea temperatures off the western Antarctic Peninsula (WAP) may be allowing lithodids to return. Imaging surveys have revealed dense populations of the lithodid Paralomis birsteini (Macpherson 1988) living on the continental slope off the WAP, but the biology of these populations remains poorly understood. We collected 51 adult P. birsteini in a trapping study on the slope off Marguerite Bay, WAP from depths of 1200–1400 m. Of the 51 crabs, 42 were males and 9 were females. Four females were ovigerous, carrying eggs at various stages of development. Rates of parasitism and limb regeneration were comparable to populations of lithodids elsewhere in the world, although the proportion of limb loss was relatively high. Externa of the parasite Briarosaccus callosus was obvious in both males and females, with one individual bearing hyperparasites (probably Liriopsis pygmaea). Gill necrosis was also observed in several dissected males. The success of contemporary lithodid populations on the Antarctic slope suggests they have the potential to expand upward to the continental shelf.

Variability in kelp forest structure along a latitudinal gradient in ocean temperature

Subtidal forests comprised of kelps and other canopy-forming macroalgae represent critically important marine habitats. Kelp forests exhibit high rates of primary productivity, magnified secondary productivity, support high levels of biodiversity and provide various ecosystem services. Compared with many other regions, kelp forests around the UK have been largely understudied despite their recognised importance and the possible impacts of environmental change factors. We conducted surveys at 12 kelp-dominated open-coast sites within four regions in the UK, spanning ~9° in latitude and ~3°C in mean sea temperature. We used a combination of quadrat-scale abundance and percent cover data as well as transect-scale canopy cover estimates to quantify ecological structure at multiple spatial scales. Kelp forest structure varied significantly between sites (nested within region) and also between regions. Regional-scale differences were principally driven by a higher abundance/cover of Alaria esculenta at the colder northern regions (i.e. north and west Scotland), and the presence of the Lusitanian kelp Laminaria ochroleuca at some sites in the southernmost region (i.e. southwest England) but nowhere else. The kelp Laminaria hyperborea dominated all sites and varied significantly between sites but not regions. All assemblage-level and population-level response variables were highly variable between sites within regions, suggesting that environmental factors varying at corresponding spatial scales (e.g. wave exposure, turbidity, sedimentation) are important drivers of pattern. The detection of regional-scale variability suggests that predicted changes in ocean climate, particularly increased sea temperature, may lead to changes in kelp forest structure in the future, with poleward range contractions (for A. esculenta) and expansions (for L. ochroleuca) likely. However, as the distribution-abundance patterns of the assemblage dominant L. hyperborea did not vary predictably with ocean temperature at this spatial scale, the fundamental structure of these habitats may be more influenced by localised factors, at least in the short-term. The relative importance of multiple, concurrent environmental change factors in structuring UK kelp forests remains largely unknown.

Cardiac performance: a thermal tolerance indicator in scallops

Thermal tolerance has become an active research area in marine poikilotherms due to the influence of increased sea temperature caused by global warming. Previous indicators of thermal tolerance in bivalves are generally laborious and time-consuming and even require killing the specimens. In this study, we demonstrated that heart rate (HR) was a stable and reliable indicator for scallop physiological status by applying an infrared-based cardiac performance monitoring system. The feasibility of HR-based Arrhenius break temperatures (ABTs) as a scallop thermal tolerance indicator was evaluated by investigating ABTs of four species with different thermal limits, including the Yesso scallop (Patinopecten yessoensis), the Zhikong scallop (Chlamys farreri), the bay scallop (Argopecten irradians), and the Catarina scallop (Argopecten ventricosus). In accordance with the thermal limits, ABTs of the Yesso scallop, Zhikong scallop, bay scallop, and Catarina scallop were 22.03 ± 0.19, 29.10 ± 0.25, 32.20 ± 0.25, and 34.09 ± 0.19 °C, respectively, suggesting that the ABT could indicate thermal limits in interspecific scallops. Variations in the ABTs were observed among intraspecific scallops with different sizes, weights, and ages, suggesting that smaller and younger scallops tend to have higher thermal limits. Significant differences in ABT were also observed between pre- and post-spawning individuals, implying that spawning behavior could decrease scallop thermal limits. The above results suggest that HR-based ABT can detect not only interspecific but also intraspecific thermal tolerance in scallops. This study reports the feasibility of infrared-based cardiac performance as a rapid, efficient, and noninvasive indicator for bivalve thermal tolerance.

Quantification of climate change implications for water-based management: A case study of oyster suitability sites occurrence model along the Kenya coast

To ensure long-term sustainability of the littoral marine ecosystem for water-based management and aquaculture potential, it is necessary to quantify and project the effect of sea warming on the resident biota. This study evaluated the potential of an oyster Suitability Sites Occurrence Model (SSOM) to predict the status of littoral areas in the future due to sea warming. Data sources comprised Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat 7 ETM+. The suitable sites were ranked on a scale of 1 (least suitable) to 5 (most suitable). In the suitability model, score 5 had the highest proportion (35.8%) of oyster suitability which shrank to 16.2% with a 4°C increase in sea temperature. Future increases in sea temperature are likely to cause shrinkage in the spatial extent of most suitable and suitable oyster sites. Thus changes in marine oyster suitability in littoral zones are predicted to worsen gradually as sea temperatures increase in the future. Differences in the recorded sea temperature of ≤6°C within and between sites may influence spatial variations in oyster habitat due to future sea warming. Such concepts could form an alternative scientific basis for quantification of potential global climate change effects on biodiversity for marine systems policy adaptation analysis, aquaculture potential, and management.

Seeing Through Fishers’ Lenses

Insights from traditional ecological knowledge (TEK) of the marine environment are difficult to integrate into conventional science knowledge (CSK) initiatives. Where TEK is integrated into CSK at all, it is usually either marginalized or restricted to CSK modes of interpretation, hence limiting its potential contribution to the understanding of social-ecological systems. This study uses semi-directive interviews, direct observations, and structured open-ended questionnaires ( n = 103) to explore TEK of marine ecological changes occurring within the Mafia Island Marine Park, Tanzania, and factors contributing to these changes. It illuminates TEK insights that can be valuable in parallel with CSK to provide a more nuanced understanding of ecological changes. In some areas, fishers observed coral reef growth, increased fish abundance, and increased sea temperatures, whereas in others, they reported decreases in sea level, coral cover, fish abundance, catch composition, catch quantities, and fish size. They associated these changes with interrelated factors emanating from environmental processes, conservation outcomes, marketing constraints, population dynamics, and disappearance of cultural traditions. Utilizing TEK without restricting it to CSK modes of interpretation has the potential to improve CSK initiatives by promoting complementarity and mutual enrichment between the two kinds of knowledge, thereby contributing new insights that may enhance adaptive management and resilience in social-ecological systems.

Proyección de cambios en la temperatura superficial del mar del Golfo de California y efectos sobre la abundancia y distribución de especies arrecifales

The Gulf of California is important because of its high biodiversity and because it is a key area for artisanal fisheries in Mexico. There are current concerns regarding threats to the Gulf, such as global warming, that have caused major changes in marine communities. Consequently, the aim of this study was to estimate the possible impact of increasing ocean temperature on key species. Potential effects of such increase on reef species are thus estimated in this paper. In order to prepare this estimate, sea surface temperature (SST) was obtained from the NOAA database, and a temperature change trend model was constructed. Biological data was obtained from visual censuses of six regions within the Gulf between 2005 and 2007. A stepwise linear model was used to forecast potential changes in species abundance and distribution. It is estimated that by 2050 average temperature will increase 0.63°C, causing abundance of species of economic value to significantly decrease south of 25° N. Finally, the response of the 20 most abundant fish species in the Gulf was modeled to estimate changes at community structure level. The simulation shows an imbalance in the function and structure of assemblages. Clearly, increasing sea temperature will bring an imbalance in the composition and the ecological function of the reef systems gradually changing the relative abundances of species. Therefore, the implementation of effective monitoring programs of communities would be an essential tool to detect future effects of global warming.

The diet, growth and survival of Razorbill Alca torda chicks in the southern Barents Sea

Over 32 years (1981–2013), Razorbills Alca torda breeding at Hornoya, NE Norway fed their chicks on capelin Mallotus villosus , sandeels Ammodytes spp. and, sometimes, I-group herring Clupea harengus . It seems that Razorbills are opportunistic and feed their chicks the youngest stages of herring in years when the latter are numerous in the southern Barents Sea. Increasing sea temperatures and resulting shifts in fish distribution may result in fewer capelin and more herring and sandeels in the chick diet.

Pemulihan Komunitas Karang Keras Pasca Pemutihan Karang di Amed Bali

Climate change is now recognized as one of the greatest threats to worldwide coral reefs with one of the most serious and immediate threats of mass coral bleaching associated with increasing sea temperatures. Coral bleaching occurred in a few coral reefs throughout the world in 2010. Coral reef in Amed’s coastal area was the one of the reefs that experienced and affected by coral bleeching incident. This study aims to assess recovery of hard coral community in post-bleaching in 2010. A survey method was used to collect primary data. Data sets also supported by secondary data. This study results were hard coral community recovered in 2013, as its percentage cover increased up to 49.00%. However, macroalgae decreased up to 0.67%. Hard coral recruitment in 2013 increased up to 21 individual/m2.

The 2014 southeast Brazil austral summer drought: regional scale mechanisms and teleconnections

The southeast region of Brazil experienced in austral summer 2014 a major drought event leading to a number of impacts in water availability for human consumption, agricultural irrigation and hydropower production. This study aims to perform a diagnostic analysis of the observed climate conditions during this event, including an inspection of the occurred precipitation anomalies in the context of previous years, and an investigation of possible relationships with sea surface temperatures and atmospheric circulation patterns. The sea surface temperature analysis revealed that the southwestern South Atlantic Ocean region near the coast of southeast Brazil showed strong negative association with precipitation over southeast Brazil, indicating that increased sea temperatures in this ocean region are consistent with reduced precipitation as observed in summer 2014. The circulation analysis revealed prevailing anti-cyclonic anomalies at lower levels (850 hPa) with northerly anomalies to the west of southeast Brazil, channeling moisture from the Amazon towards Paraguay, northern Argentina and southern Brazil, and drier than normal air from the South Atlantic Ocean towards the southeast region of Brazil. This circulation pattern was found to be part of a large-scale teleconnection wave train linked with the subsidence branch of the Walker circulation in the tropical east Pacific, which in turn was generated by an anomalous tropical heat source in north/northeastern Australia. A regional Hadley circulation with an ascending branch to the south of the subsidence branch of the Walker circulation in the tropical east Pacific was identified as an important component connecting the tropical and extratropical circulation. The ascending branch of this Hadley circulation in the south Pacific coincided with an identified Rossby wave source region, which contributed to establishing the extratropical component of the large-scale wave train connecting the south Pacific and the Atlantic region surrounding southeast Brazil. This connection between the Pacific and the Atlantic was confirmed with Rossby ray tracing analyses. The local circulation response was associated to downward air motion (subsidence) over Southeast Brazil, contributing to the expressive negative precipitation anomalies observed during summer 2014, and leading to a major drought event in the historical context. The analysis of atmospheric and oceanic patterns of this event helped defining a schematic framework leading to the observed drought conditions in southeast Brazil, including the involved teleconnections, blocking high pressure, radiative and humidity transport effects.

Low temperature tolerance of a sea urchin pathogen: Implications for benthic community dynamics in a warming ocean

Disease outbreaks in the sea urchin Strongylocentrotus droebachiensis on the Atlantic coast of Nova Scotia have increased in frequency over the last 35years, in association with increasing sea temperatures and strong storm events. Previous studies suggest that the causative agent of disease, the pathogenic amoeba Paramoeba invadens, cannot withstand winter sea temperatures on this coast, and may be an alien species. Consequently, recurrent epizootics result from repeated introductions of this pathogen, possibly due to advection or vertical mixing associated with storm events. Here we test an alternative hypothesis that P. invadens has established resident populations, either through physiological adaptation to low winter temperatures, or because winter minima have increased since 1980. To test this hypothesis, we manipulated culture temperatures of P. invadens isolated from moribund sea urchins during a disease outbreak in 2012. Specific growth rates of P. invadens in culture at 0.5 to 18.0°C were similar to those observed in the early 1980s, providing no evidence of physiological adaptation. P. invadens declined to extinction in culture after ~1month at 0.5°C and 2.0°C, but survived for 3months at 3.5°C, as indicated by recovery of cultures following transfer to optimal temperature. These results indicate a lower temperature tolerance threshold around 2–3°C, which is consistent with observational data of recurrent mass mortalities of sea urchins in 1983 and 2012 in the absence of a storm but following relatively warm winters. A trend of increasing minimum temperatures in winter indicates that P. invadens could undergo a range expansion to establish a resident population in Nova Scotia within 1–2 decades. This is expected to increase the resilience of the kelp-bed state of the benthic ecosystem but result in the complete collapse of the sea urchin fishery.

Distribution, abundance, and feeding ecology of baleen whales in Icelandic waters: have recent environmental changes had an effect?

The location of Iceland at the junction of submarine ridges in the North-East Atlantic where warm and cold water masses meet south of the Arctic Circle contributes to high productivity of the waters around the island. During the last two decades, substantial increases in sea temperature and salinity have been reported. Concurrently, pronounced changes have occurred in the distribution of several fish species and euphausiids. The distribution and abundance of cetaceans in the Central and Eastern North Atlantic have been monitored regularly since 1987. Significant changes in the distribution and abundance of several cetacean species have occurred in this time period. The abundance of Central North Atlantic humpback and fin whales has increased from 1,800 to 11,600 and 15,200 to 20,600, respectively, in the period 1987-2007. In contrast, the abundance of minke whales on the Icelandic continental shelf decreased from around 44,000 in 2001 to 20,000 in 2007 and 10,000 in 2009. The increase in fin whale abundance was accompanied by expansion of distribution into the deep waters of the Irminger Sea. The distribution of the endangered blue whale has shifted northwards in this period. The habitat selection of fin whales was analyzed with respect to physical variables (temperature, depth, salinity) using a generalized additive model, and the results suggest that abundance was influenced by an interaction between the physical variables depth and distance to the 2000m isobaths, but also by sea surface temperature and sea surface height, However, environmental data generally act as proxies of other variables, to which the whales respond directly. Overall, these changes in cetacean distribution and abundance may be a functional feeding response of the cetacean species to physical and biological changes in the marine environment, including decreased abundance of euphausiids, a northward shift in summer distribution of capelin and a crash in the abundance of sand eel.