Sea Ice Perturbation and Mass Starvation of Thick-billed Murres in the Northwest Atlantic Ocean

"Winter kill" syndrome is a disease in channel catfish, Ictalurus punctatus, which occurs during the winter months. The syndrome, characterized by cutaneous fungal lesions, has recently been described in detail and is an infectious disease better termed "winter saprolegniosis." A ubiquitous fungus, Saprolegnia sp., is the causative organism responsible for the outbreak of disease in channel catfish rendered immunocompromised by a rapid drop in water temperature. Histological examination of fungal skin lesions from pond- or laboratory-infected channel catfish revealed a complete lack of leukocytic infiltration around invading hyphae. Presumably, the lack of an inflammatory/immune response is attributable to either low temperature-mediated in vivo immunosuppression and/or fungal suppression or evasion of the fish's immune system. The present study was initiated to determine if the fungus was suppressing or evading the channel catfish immune system. The questions asked were: whether channel catfish held at an immunologically permissive temperature (24°C) can mount an immune response if inoculated with viable Saprolegnia sp., and if so, what is the nature of the response, i.e., is it natural or acquired or humoral or cell-mediated? These questions are of great importance if a vaccine is to be developed for winter saprolegniosis. In order to determine if humoral immunity was involved, channel catfish held at 24°C were given intra-peritoneal injections of Saprolegnia sp, and monitored for the production of antibodies for two months. All injected fish failed to produce detectable antibodies, suggesting that the immune response may be predominantly cellular rather than humoral. Consequently, fish held at 24°C were given intra-muscular injections of viable Saprolegnia sp. and monitored for localized cellular immune responses. During the ensuing 16 days, fish exhibited acute phase responses, i.e., localized raised hemorrhagic lesions of ≤1 cm around the injection site were observed. The response peaked on day 8 and was totally resolved by day 16. Histopathology revealed a foreign body inflammatory response with the classical appearance of giant multinucleated cells. Granulocytes initially infiltrated the site, followed later by predominantly lymphocytes. Leukocytes were also seen attached to fungal hyphae early in the response. These results indicate that Saprolegnia sp. likely neither evades nor suppresses the channel catfish immune system. It is proposed that future therapeutic and prophylactic measures to prevent the occurrence of winter saprolegniosis should focus on enhancing cellular defenses to Saprolegnia sp.

Abstract. Previous studies have led to the development of a laboratory model for a disease termed ‘winter saprolegniosis’, locally referred to as ‘winter kill’, occurring in channel catfish, Ictalurus punctatus Rafinesque, raised in commercial ponds in the southeastern United States. In the laboratory, the onset of disease was routinely brought about by a combination of two related factors: (1) a rapid drop in water temperature which induces immunosuppression in catfish; and (2) maintenance of low water temperatures (∼10°C), which favour the proliferation of an ubiquitous fungus of the genus Saprolegnia to produce high levels of fungal zoospores (≥5 spores ml−1). In this study, two commercial catfish ponds were monitored for over one year to determine if the above factors occurred in the field and could be correlated with outbreaks of winter saprolegniosis. It was noted that passages of severe cold weather fronts were able to drop pond water temperatures ≥10°C within 24h and that such decreases in water temperature were associated with immunosuppression of the catfish in the ponds. Furthermore, when Saprolegnia sp. zoospore levels were ≥5 spores ml‐1, the immunocompromised catfish exhibited overt signs of winter saprolegniosis. If one of the factors implicated in the induction of disease was missing, fish in the ponds remained healthy. In addition, the onset of disease in the ponds appeared independent of pH and oxygen, total ammonia nitrogen and un‐ionized ammonia levels. Collectively, these field results confirm the laboratory‐based hypothesis concerning the aetiology of winter saprolegniosis in channel catfish.

All seabirds in the northwest Atlantic Ocean migrate, but timing and routes are not well understood. We evaluate existing knowledge on seabird migration with data from the Programme intégré de recherches sur les oiseaux pélagiques (PIROP) data base, using observations of immature and moulting seabirds to track migration of the following species: Northern Fulmar (Fulmarus glacialis), Greater Shearwater (Puffinus gravis), Northern Gannet (Morus bassanus), Herring Gull (Larus argentatus), Iceland Gull (Larus glaucoides), Glaucous Gull (Larus hyperboreus), Great Black-backed Gull (Larus marinus), Black-legged Kittiwake (Rissa tridactyla), and Thick-billed Murre (Uria lomvia). The distributions of immature and moulting birds show strong seasonal patterns in the northwest Atlantic, and new transition zones and clear biological borderlines for seabird distribution were found. New data on timing and location of moulting Thick-billed Murres are presented. The southern Labrador Banks and Grand Banks (Thick-billed Murre, Northern Fulmar) and southeast Newfoundland and Georges Bank (Greater Shearwater) were identified as moulting grounds. In terms of marine conservation the following areas seem to be important for part of the life cycle of the species named: western Greenland, Cape Cod, Grand Banks, Labrador Banks, southwest Newfoundland, and the Grand Manan area.

In this study, the wind direction and the wind speed of the nearest temperature observations point of the National Weather Service was analyzed in order to investigate the rapid rise and drop of water temperature in the East Coast appeared after passing of the 2015 typhoon No. 9 and 11. Then the figures were simulated and analyzed using the WRF(weather research and forecast) model to investigate in more detailed path of the typhoon as well as the changes in the wind field. The results were as follows. A sudden drop of water temperature was confirmed due to upwelling on the East coast when ninth typhoon Chanhom is transformed from tropical cyclones into extra tropical cyclone, then kept moving eastwards from Pyongyang forming a strong southerly wind after 13th and this phenomenon lasted for two days. The high SST(sea surface temperature) is confirmed due to a strong northerly wind by 11th typhoon Nangka. This strong wind directly affected the east coast for three days causing the Ekman effect which transported high offshore surface waters to the coast. The downwelling occurred causing an accumulation of high temperature surface water. As a results, the SST of 15m and 25m rose to that of 5m.

We examine how ocean climate variability influences the reproductive phenology and demography of the seabird Cassin's Auklet (Ptychoramphus aleuticus) across approximately 2500 km of its breeding range in the oceanographically dynamic California Current System along the west coast of North America. Specifically, we determine the extent to which ocean climate conditions and Cassin's Auklet timing of breeding and breeding success covary across populations in British Columbia, central California, and northern Mexico over six years (2000-2005) and test whether auklet timing of breeding and breeding success are similarly related to local and large-scale ocean climate indices across populations. Local ocean foraging environments ranged from seasonally variable, high-productivity environments in the north to aseasonal, low-productivity environments to the south, but covaried similarly due to the synchronizing effects of large-scale climate processes. Auklet timing of breeding in the southern population did not covary with populations to the north and was not significantly related to local oceanographic conditions, in contrast to northern populations, where timing of breeding appears to be influenced by oceanographic cues that signal peaks in prey availability. Annual breeding success covaried similarly across populations and was consistently related to local ocean climate conditions across this system. Overall, local ocean climate indices, particularly sea surface height, better explained timing of breeding and breeding success than a large-scale climate index by better representing heterogeneity in physical processes important to auklets and their prey. The significant, consistent relationships we detected between Cassin's Auklet breeding success and ocean climate conditions across widely spaced populations indicate that Cassin's Auklets are susceptible to climate change across the California Current System, especially by the strengthening of climate processes that synchronize oceanographic conditions. Auklet populations in the northern and central regions of this ecosystem may be more sensitive to changes in the timing and variability of ocean climate conditions since they appear to time breeding to take advantage of seasonal productivity peaks.

Capelin (Mallotus villosus) is a commercially exploited, key forage-fish species found in the boreal waters of the North Pacific and North Atlantic Oceans. We examined the population structure of capelin throughout their range in the Canadian northwest Atlantic Ocean using genetic-based methods. Capelin collected at ten beach and five demersal spawning locations over the period 2002 through 2008 (N = 3,433 fish) were genotyped using six polymorphic microsatellite loci. Temporally distinct samples were identified at three beach spawning locations: Chance Cove, Little Lawn and Straitsview, Newfoundland. Four capelin stocks are assumed for fisheries management in the northwest Atlantic Ocean based on meristics, morphometrics, tag returns, and seasonal distribution patterns. Our results suggested groupings that were somewhat different than the assumed structure, and indicate at least seven genetically defined populations arising from two ancestral populations. The spatial mosaic of capelin from each of the two basal cluster groups explains much of the observed geographic variability amongst neighbouring samples. The genetic-defined populations were resolved at Jost’s D est ≥ 0.01 and were composed of fish collected 1) in the Gulf of St. Lawrence, 2) along the south and east coasts of Newfoundland, 3) along coastal northern Newfoundland and southern Labrador, 4) along coastal northern Labrador, 5) near the Saguenay River, and at two nearshore demersal spawning sites, 6) one at Grebes Nest off Bellevue Beach on the east coast of Newfoundland, and 7) one off the coast of Labrador at Domino Run. Moreover, the offshore demersal spawners on the Scotian Shelf and Southeast Shoal appeared to be related to the inshore demersal spawners at Grebes Nest and in Domino Run and to beach spawners from the Gulf of St. Lawrence.

The hypothesis that liver lipid accumulation in fish is an adaptive strategy to survive the winter in the high-altitude environment was assessed in this study. During summer 2019, specimens of Cottus gobio were sampled in 15 watercourses of Friuli Venezia-Giulia Region (Italy) to verify if hepatic steatosis is or not normally present in the species. To do this, hepatic vacuolization was assessed by histology using a semiquantitative score. Furthermore, C. gobio were also captured during the ice-free season at Dimon Lake (1872 m a.s.l.) and But Stream (520 m a.s.l.) to compare the trend in lipid accumulation: water temperature, hepatosomatic index (HSI), gonadosomatic index (GSI), Fulton’s condition factor (K), and lipid area percentage (lipid %) were measured monthly. Findings revealed that liver steatosis is rather common in C. gobio. However, the trend in lipid accumulation of this species differed between Dimon Lake and But Stream. Based on the HSI and the GSI, the reproductive cycles differed in fish from the two environments (April–May in But Stream; May–June in Dimon Lake). While K values remained unchanged in the But Stream specimens, significant changes were recorded for Dimon specimens. The increase in lipid % from July to August in the Dimon Lake specimens coincided with greater food availability. With the rapid drop in lake water temperature in October, the lipid % decreased due to slower metabolic rate and lipid utilization from liver stores. There was a slight decrease in lipid % in the But Stream specimens, indicating that lipids were not being accumulated. Introduced years ago, the Dimon Lake bullhead population has since adapted to the winter conditions at high elevation.

Limited knowledge of year-round seabird distributions hinders efforts to assess consequences of anthropogenic threats and climate-induced changes in the marine environment. In particular, there is urgent need to understand how populations from different breeding colonies share and partition ocean habitat. Using geolocators, we identified winter habitat use patterns of 115 adult murres Uria spp. from 7 colonies, spanning the eastern Canadian coast from the high Arctic to Newfoundland, during 2007 to 2010. Thick-billed murres U. lomvia dispersed throughout the region (Davis Strait, Labrador Sea, Orphan Basin, Grand Bank) with 0 to 45% overlap of core wintering areas (50% kernel home range) among breeding populations. Common murres U. aalge concentrated on the Grand Bank and Orphan Basin, with 50 to 67% overlap among breeding populations. For both species, most individuals (up to 70%) wintered offshore, in shelf (≤500 m deep) and oceanic zones (>500 m); fewer than one-third (30%) of individuals used nearshore zones (≤50 km to shore). Tracked common murres representing >80% of the eastern Canadian breeding population converged in winter in areas of high risk from hydrocarbon exploration and extraction activity. In contrast, tracked thick-billed murres, representing ~34% of the eastern Canadian population, dispersed over a larger area and displayed more variable wintering strategies. Thus population vulnerability to spatially constrained risks may be greater for common than thick-billed murres. Populations from several colonies of both species converged on the Grand Bank and Orphan Basin, with the implications for each breeding population depending on its particular dispersal pattern. We demonstrate the utility of tracking data for highlighting areas of risk, and improving the targeting of broad-scale marine conservation efforts.

Antioxidant capacity is correlated with susceptibility to leaf spot caused by a rapid temperature drop in Saintpaulia (African violet)

Research on how intermittent water releases from hydropower plants affect the early life stages of fish has advanced in the last years, focusing not only on the direct impacts of rapid flow changes (hydropeaking), but also on the short-term fluctuations in water temperature (thermopeaking). Flow and thermal fluctuations caused by hydropeaking may affect fish movement patterns and migration at critical stages of a species’ life cycle, e.g., by inducing passive downstream drift. Using two experimental outdoor channels, we investigated how nase (Chondrostoma nasus, Cypriniformes) larvae respond to a rapid drop in water temperature during hydropeaking (simulating a cold thermopeaking event), reaching on average 5.5 °C under peak flow (maximum discharge) conditions, in comparison with a hydropeaking treatment with a constant water temperature regime. Responses of fish larvae were analyzed during acclimation, up-ramping (increase in discharge), peak flow and down-ramping (decrease in discharge) phases. Fish drift increased during peak flow in the cold thermopeaking treatment compared to hydropeaking. Higher drift rates were also negatively associated with pronounced water temperature drops during peak flow conditions. In addition, the starting temperature of the experiment influenced drift during up-ramping. Overall, the results suggest that cold thermopeaking may increase drift in the early life stages of cypriniform fish compared with hydropeaking with stable water temperature. Hence, monitoring and active water temperature adjustments following hydropower releases should be adopted as strategies to mitigate power plant-related impacts on aquatic organisms.

Movement patterns of hooded seals (Cystophora cristata) in the Northwest Atlantic in the period following moulting and prior to breeding are not well known. Here, we describe in detail the movement patterns of 21 seals for this period based on information gathered from satellite linked time depth recorders (SLTDRs). This study provides important baseline information necessary to understand the ecological requirements and patterns in habitat selection for the species. Adult and sub-adult hooded seals were tagged with SLTDRs directly after moulting in SE Greenland during July 2004, 2005 and 2007. Due to variation in tag date and arrival date to the breeding grounds, data between 1 Aug–28 Feb were used which gave all seals a track duration of 211 days (212 in 2005) except for one juvenile where the tag lasted for only 154 days. The tags yielded 36 107 location fixes (SD = 410.64, mean = 1 719.38). Although there was individual variation between seal trajectories during migration, the population shared a similar overall pattern. After moulting in July individuals travelled along the continental shelf area up to Davis Strait and Baffin Bay, thereafter moving southwards along the Labrador shelf until they arrived at the breeding grounds by March. Females tended to cut across the Labrador Sea and arrived at the Labrador shelf before heading up to the Baffin Bay area, while males tended to move straight there. The majority of the seals ended up at the Front (off Newfoundland and Southern Labrador) by March although a few of the tagged seals may have belonged to the Davis Strait breeding population and one male belonged to the Gulf of St. Lawrence breeding population. Seven seals displayed an eastward migratory pull and might have overlapped with the Northeast Atlantic population. This would support the theory of a panmitic population structure.

The non-breeding movements of marine birds were poorly known until recently, but this information is essential to understanding the risk to different geographical populations from events on the wintering grounds. We tracked the migration routes and wintering areas of Thick-billed Murre Uria lomvia from two breeding colonies in eastern Canada: Coats Island in northern Hudson Bay and The Minarets, Baffin Island, during the period August 2007–May 2008 using geolocation loggers. Birds from The Minarets moved south rapidly post-breeding and wintered principally off Newfoundland and southern Labrador, or between Newfoundland and southern Greenland, remaining south of 55°N until at least the spring equinox. Those from Coats Island remained in Hudson Bay until at least mid-November, after which they moved rapidly through Hudson Strait to winter in southern Davis Strait and the northern Labrador Sea, mostly north of 55°N. Many individuals stayed throughout the winter in areas of heavy ice cover. Adults from the two colonies appear to be completely segregated in winter and those from Coats Island probably did not enter the area of the winter hunt in Newfoundland. Unexpectedly, some birds from The Minarets wintered in waters beyond the continental slope and outside the distribution of pack ice, demonstrating that particular individuals can be wholly pelagic throughout the winter. Coats Island birds returned through Hudson Strait as soon as open water areas became available in spring. Their sojourn in Hudson Bay coincided very closely with the occurrence of areas with <90% ice cover. In spite of the relatively large error in positions obtained from geolocation loggers, our results demonstrated the value of these devices by uncovering a number of previously unknown aspects of Thick-billed Murre non-breeding ecology in the Northwest Atlantic. Comparison of the non-breeding ecology based on SST experienced in winter show that the winter niche is broader than hitherto assumed, demonstrating that separate populations may experience different selection in the face of climate change.

A rapid temperature drop during anaerobic acidogenesis in an anaerobic reactor system resulted in the sharp suppression of carbohydrate decomposition and production of volatile fatty acids. When the temperature was dropped from 30°C to 25, 20, 15°C sequentially, the numbers of bacteria were slowly reduced without showing temperature shock. The acidogenesis, however, was dramatically affected after each temperature drop; the removal efficiency of carbohydrate was reduced from 92% to 84%, 72%, 25% with showing the minima of 78%, 52% and 10% due to the rapid temperature drop respectively. This indicates that the acidogens lose the activities momentarily during the rapid temperature drop and require certain period of time to recover the activities at the adjusted fermentation temperature.

Experiments on pool boiling of water were performed under decompression. Temperature fluctuation measured with 3 thermocouples which were equipped on copper block surface by plating. Rapid temperature drops in this fluctuation arise at same times. This shows the existence of evaporation of microlayer under bubbles. The evaluation of this evaporation of the microlayer and rapid temperature drops showed the existence of a new evaporation factor in obedience to the liquid surface overheating. Temperature drops have two types at decompression. One is rapid drop due to the cavity existence and the other is slow drop due to the generation in the superheated bulk liquid on the mirror surface. This rapid temperature drop have gradual drop at first stage. For verification of gradual drops, we introduced a equation concerned micro film thickness under the bubble on the basis of the viscosity and the preservation of momentum. This equation has exponential factor about microfilms. Numerical calculations showed a good agreement with the experimental data.

Experiments on pool boiling of water were performed under decompression. Temperature fluctuation was measured with three thermocouples which were equipped on the copper block surface by plating. Rapid temperature drops in this fluctuation arise at the same times. This shows the existence of evaporation of the microlayer under bubbles. Evaluation of this evaporation of the microlayer and rapid temperature drops revealed the existence of a new evaporation factor in obedience to the liquid surface overheating. Temperature drops are of two types at decompression. One is rapid drop due to cavity existence and the other is slow drop due to generation in the superheated bulk liquid on the mirror surface. This rapid temperature drop is gradual at the first stage. For verification of gradual drops, we introduced an equation concerning micro film thickness under the bubble on the basis of the viscosity and the preservation of momentum. This equation has an exponential factor for microfilms. Numerical calculations showed good agreement with the experimental data. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(7): 567–581, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10102