scholarly journals Mapping Antarctic suspension feeder abundances and seafloor food-availability, and modelling their change after a major glacier calving

2018 ◽  
Author(s):  
Jan Jansen ◽  
Nicole A. Hill ◽  
Piers K. Dunstan ◽  
Eva A. Cougnon ◽  
Benjamin K. Galton-Fenzi ◽  
...  
Keyword(s):  
Food Availability ◽  
Food Supply ◽  
Ocean Surface ◽  
Ocean Model ◽  
Suspension Feeder ◽  
Study Region ◽  
Glacier Tongue ◽  
Total Food ◽  
Before And After ◽  
Horizontal Flux

AbstractSeafloor communities are a critical part of the unique and diverse Antarctic marine life. Processes at the ocean-surface can strongly influence the diversity and abundance of these communities, even when they live at hundreds of meters water depth. However, even though we understand the importance of this link, there are so far no quantitative spatial predictions on how seafloor communities will respond to changing conditions at the ocean surface.Here, we map patterns in abundance of important habitat-forming suspension feeders on the seafloor in East Antarctica, and predict how these patterns change after a major disturbance in the icescape, caused by the calving of the Mertz Glacier Tongue. We use a purpose-built ocean model for the time-period before and after the calving of the Mertz-Glacier Tongue in 2010, data from satellites and a validated food-availability model to estimate changes in horizontal flux of food since the glacier calving. We then predict the post-calving distribution of suspension feeder abundances using the established relationships with the environmental variables, and changes in horizontal flux of food.Our results indicate strong increases in suspension feeder abundances close to the glacier calving site, fueled by increased food supply, while the remainder of the region maintains similar suspension feeder abundances despite a slight decrease in total food supply. The oceanographic setting of the entire region changes, with a shorter ice-free season, altered seafloor currents and changes in food-availability.Our study provides important insight into the flow-on effects of a changing icescape on seafloor habitat and fauna in polar environments. Understanding these connections is important in the context of current and future effects of climate change, and the mapped predictions of the seafloor fauna as presented for the study region can be used as a decision-tool for planning potential marine protected areas, and for focusing future sampling and monitoring initiatives.

scholarly journals Spatial Management Measures Alter Vessel Behavior in the Aleutian Archipelago

2021 ◽  
Vol 7 ◽  
Author(s):  
Benjamin K. Sullender ◽  
Kelly Kapsar ◽  
Aaron Poe ◽  
Martin Robards
Keyword(s):  
North Pacific ◽  
Risk Mitigation ◽  
Spatial Scales ◽  
Great Circle ◽  
Ecological Impacts ◽  
Study Region ◽  
The North ◽  
Management Measures ◽  
Before And After ◽  
The North Pacific

The Aleutian Archipelago and surrounding waters have enormous ecological, cultural, and commercial significance. As one of the shortest routes between North American and Asian ports, the North Pacific Great Circle Route, which crosses through the Aleutian Archipelago, is traveled by thousands of large cargo ships and tanker vessels every year. To reduce maritime risks and enhance navigational safety, the International Maritime Organization built upon earlier offshore routing efforts by designating five Areas To Be Avoided (ATBAs) in the Aleutian Islands in 2016. The ATBAs are designed to keep large vessels at least 50 nautical miles (93 km) from shore unless calling at a local port or transiting an authorized pass between islands. However, very few studies have examined the effectiveness of ATBAs as a mechanism for changing vessel behavior and thereby reducing the ecological impacts of maritime commerce. In this study, we use 4 years of satellite-based vessel tracking data to assess the effectiveness of the Aleutian ATBAs since their implementation in 2016. We determined whether vessels transiting the North Pacific Great Circle Route changed behavior after ATBA implementation, both in terms of overall route selection and in terms of compliance with each ATBA boundary. We found a total of 2,252 unique tankers and cargo vessels >400 gross tons transited the study region, completing a total of 8,794 voyages. To quantify routing changes of individual vessels, we analyzed the 767 vessels that transited the study region both before and after implementation. The percentage of voyages transiting through the boundaries of what would become ATBAs decreased from 76.3% in 2014–2015 (prior to ATBA designation) to 11.8% in 2016–2017 (after implementation). All five Aleutian ATBAs had significant increases in compliance, with the West ATBA showing the most dramatic increase, from 32.1% to 95.0%. We discuss the framework for ATBA enforcement and highlight the value of local institutional capacity for real-time monitoring. Overall, our results indicate that ATBAs represent a viable strategy for risk mitigation in sensitive ecological areas and that through monitoring, spatial protections influence vessel route decisions on multiple spatial scales.

scholarly journals Mapping Antarctic Suspension Feeder Abundances and Seafloor Food-Availability, and Modeling Their Change After a Major Glacier Calving

2018 ◽  
Vol 6 ◽  
Author(s):  
Jan Jansen ◽  
Nicole A. Hill ◽  
Piers K. Dunstan ◽  
Eva A. Cougnon ◽  
Benjamin K. Galton-Fenzi ◽  
...  
Keyword(s):  
Food Availability ◽  
Suspension Feeder

Ocean Model Simulation of Southern Indian Ocean Surface Currents

2007 ◽  
Vol 30 (4) ◽  
pp. 345-354 ◽  
Author(s):  
Anshu Prakash Mishra ◽  
S. Rai ◽  
A. C. Pandey
Keyword(s):  
Indian Ocean ◽  
Model Simulation ◽  
Ocean Surface ◽  
Ocean Model ◽  
Southern Indian Ocean ◽  
Surface Currents ◽  
Ocean Surface Currents

Differences in growth rate, body condition, habitat use and food availability between island and mainland lizard populations ofAnolis nebulosusin Jalisco, Mexico

2014 ◽  
Vol 30 (5) ◽  
pp. 493-501 ◽  
Author(s):  
Héctor Hugo Siliceo-Cantero ◽  
Andrés García
Keyword(s):  
Growth Rate ◽  
Habitat Use ◽  
Food Availability ◽  
Body Condition ◽  
Food Supply ◽  
Geographic Isolation ◽  
Seasonal Fluctuations ◽  
Continental Population ◽  
Two Populations

Abstract:Lizards of the genusAnolishave been widely studied, however, little is known about the effects of environmental seasonality, food availability and geographic isolation on body condition, growth rate and habitat use of lizards. The existence of an insular and a continental population ofAnolis nebulosus(clouded anole), separated by only 0.47 km, represents an ideal opportunity to address this topic. We compared seasonal fluctuations in food availability (arthropod density) for anoles, as well as body condition, growth rate and habitat use in the two populations. Food availability throughout the year was sampled every 2 mo by trapping arthropods at each site. Lizards were also monitored and measured every 2 mo by surveying three quadrats in each site over 2 y giving a total of 30 visits for each quadrat. Results suggested that composition and density of food supply was similar for the two populations. Nevertheless, food supply responded to seasonality of rainfall, with an increase of 1.5 times during the rainy season. Despite similarity in food availability, insular anoles had body condition that was 5–10 times better, with growth rate twice as fast, and used similar perches. The role of predation, and inter- and intraspecific competition are discussed as possible drivers.

Testing the intergenerational conflict hypothesis: factors affecting adoptions in Audouin's gulls, Larus audouinii

1999 ◽  
Vol 77 (3) ◽  
pp. 433-439 ◽  
Author(s):  
Daniel Oro ◽  
Meritxell Genovart
Keyword(s):  
Food Availability ◽  
Food Supply ◽  
Foster Parents ◽  
Intergenerational Conflict ◽  
Factors Affecting ◽  
Breeding Seasons ◽  
Ground Nesting ◽  
Larus Audouinii

We studied chick adoption in Audouin's gull, Larus audouinii, a ground-nesting seabird, to test several predictions made by the intergenerational-conflict hypothesis (ICH). The effects of food availability on adoptions were considered by comparing two breeding seasons with differing food supply. As predicted, adoptions were significantly more frequent when food was in shorter supply (48% of broods affected) than when it was more available (18.5%). Adoptions occurred during the first week of the chick-rearing stage; after that, aggression by adults towards intruding chicks increased significantly, which suggests that mechanisms of parent-offspring recognition were established. Foster parents incurred certain costs, since their offspring had lower chances of survival than those in control broods. However, contrary to the ICH hypothesis, adoptees did not select foster broods in relation to the age of the resident chicks. Survival of wandering chicks was no higher than that of chicks who stayed in their natal brood. Results suggest that chicks move only as a response to neighboring chicks being fed by an adult, and in Audouin's gulls, adoptions might be considered reproductive errors.

scholarly journals Ocean Surface Currents in the northern Nordic Seas from a combination of multi-mission satellite altimetry and numerical modeling

2020 ◽  
Author(s):  
Felix L. Müller ◽  
Denise Dettmering ◽  
Claudia Wekerle ◽  
Christian Schwatke ◽  
Marcello Passaro ◽  
...  
Keyword(s):  
Sea Ice ◽  
Satellite Altimetry ◽  
Barents Sea ◽  
Ocean Surface ◽  
Ocean Model ◽  
Main Step ◽  
Surface Currents ◽  
Data Set ◽  
Ocean Surface Currents ◽  
Ocean Topography

<p>Satellite altimetry is an important part of the Global Geodetic Observing System providing precise information on sea level on different spatial and temporal scales. Moreover, satellite altimetry-derived dynamic ocean topography heights enable the computation of ocean surface currents by applying the well-known geostrophic equations. However, in polar regions, altimetry observations are affected by seasonally changing sea-ice cover leading to a fragmentary data sampling.</p><p>In order to overcome this problem, an ocean model is used to fill in data gaps. The aim is to obtain a homogeneous ocean topography representation that enables consistent investigations of ocean surface current changes. For that purpose, the global Finite Element Sea-ice Ocean Model (FESOM) is used. It is based on an unstructured grid and provides daily water elevations with high spatial resolution.</p><p><span>The combination is done based on a Principal Component Analysis (PCA) after reducing both quantities by their constant and seasonal signals. In the main step, the </span><span>most dominant spatial patterns of the modeled water heights </span><span>as provided by the PCA are linked with the </span><span>temporal variability of </span><span>the estimated </span><span>dynamic ocean topography elevations</span><span> from altimetry. At the end, the seasonal signal as well as the absolute reference from altimetry is added back to the data set.</span></p><p><span>T</span><span>his </span><span>contribution</span><span> describes the combination process </span><span>as well as the generated final product: </span><span> a daily, more than 17 years covering dataset of geostrophic ocean currents. The combination is done for the </span><span>marine </span><span>region</span><span>s</span><span> Greenland Sea, Barents Sea and the Fram Strait and includes sea surface height observations of the ESA altimeter satellites ERS-2 and Envisat. In order to evaluate the </span><span>combination </span><span>results, independent </span><span>surface </span><span>drifter </span><span>observations</span><span>, </span><span>corrected for</span> <span>a-geostrophic velocity </span><span>components, are used.</span></p>

scholarly journals Effect of Food Availability on Arrival and Departure Decisions of Harlequin Ducks at Diurnal Feeding Grounds

The Condor ◽  
2001 ◽  
Vol 103 (4) ◽  
pp. 870-874 ◽  
Author(s):  
Michael S. Rodway ◽  
Fred Cooke
Keyword(s):  
Food Availability ◽  
Food Supplementation ◽  
Natural Food ◽  
Clupea Pallasi ◽  
Histrionicus Histrionicus ◽  
Before And After ◽  
Harlequin Ducks ◽  
Near Shore ◽  
Effect Of Food ◽  
Departure Decisions

Abstract We investigated three types of decisions made by Harlequin Ducks (Histrionicus histrionicus) in moving between nearshore feeding and offshore resting areas: when to move, whether to move synchronously, and whether to form dense flocks on the roosting grounds. We used the spawning of Pacific herring (Clupea pallasi) as a natural food-supplementation experiment. Birds arrived at nearshore feeding areas a few minutes later and departed almost an hour earlier relative to sunrise and sunset when spawn was available than before and after. Cloud cover and high winds resulted in earlier departures, especially during spawning. Arriving, departing, and offshore groups consisted most frequently of two ducks, and birds showed little tendency to synchronize movements or to form dense flocks when resting. Results indicate that Harlequin Ducks avoid crepuscular and nocturnal periods near shore when not constrained by food availability and the length of daylight in which to feed. Efecto de la Disponibilidad de Alimento en las Decisiones de Arribo y Partida de Histrionicus histrionicus en Áreas de Alimentación Diurna Resumen. Investigamos tres tipos de decisiones hechas por Histrionicus histrionicus (Pato Arlequín) al moverse entre áreas de alimentación cercanas a la costa y áreas de reposo mar adentro: cuándo moverse, si se mueven de modo sincrónico, y si forman bandadas densas en las áreas de reposo. Utilizamos el desove del arenque del Pacífico (Clupea pallasi) como un experimento de suplemento de alimento natural. En relación al amanecer y anochecer, las aves llegaron a las áreas de alimentación cercanas a la costa unos minutos después y se fueron casi una hora más temprano cuando los huevos de peces estuvieron disponibles que cuando no lo estuvieron, ya sea antes o después. Cobertura de nubes y fuertes vientos trajeron aparejadas partidas más tempranas, especialmente durante la etapa de desove. Los grupos que llegaban, partían y los que se encontraban mar adentro estuvieron en su mayoría conformados por dos patos, y las aves en general no tendieron a sincronizar sus movimientos o a formar grupos densos durante el reposo. Los resultados indican que H. histrionicus evita permanecer cerca de la costa durante períodos crepusculares y nocturnos cuando no se haya limitado por la disponibilidad de alimentos y por la cantidad de horas de luz para alimentarse.

Effects of temperature and food on the fecundity and egg development rates of Boeckella symmetrica Sars (Copepoda : Calanoida)

1981 ◽  
Vol 32 (6) ◽  
pp. 997 ◽  
Author(s):  
IO Woodward ◽  
RWG White
Keyword(s):  
Lower Limit ◽  
Clutch Size ◽  
Food Availability ◽  
Food Supply ◽  
Egg Size ◽  
Food Regime ◽  
Egg Development ◽  
Thermal Range ◽  
Effects Of Temperature ◽  
Increasing Temperature

The effects of temperature and food regime on the fecundity and egg development of B. symmetrica are presented. Clutch size decreases with increasing temperature and decreased food availability. At low food levels; there is increased variability in clutch size; this increase is less marked at lower temperatures. Duration of egg development decreases hyperbolically with increasing temperature; there may be a slight increase with increased food availability. Egg size decreases linearly with increasing temperature: food supply may have some effect. Variability of egg size decreases with decreasing temperature. Egg mortality is highest towards the lower limit of the natural thermal range of B. symmetrica and lowest near the middle.

scholarly journals The influence of food supply on the response of Olympia oyster larvae to ocean acidification

2013 ◽  
Vol 10 (3) ◽  
pp. 5781-5802 ◽  
Author(s):  
A. Hettinger ◽  
E. Sanford ◽  
T. M. Hill ◽  
J. D. Hosfelt ◽  
A. D. Russell ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ocean Acidification ◽  
Food Availability ◽  
Food Supply ◽  
Atmospheric Carbon Dioxide ◽  
Shell Growth ◽  
Dry Weight ◽  
Food Level ◽  
Negative Consequences ◽  
Olympia Oyster

Abstract. Increases in atmospheric carbon dioxide drive accompanying changes in the marine carbonate system as carbon dioxide (CO2) enters seawater and alters its pH (termed "ocean acidification"). However, such changes do not occur in isolation, and other environmental factors have the potential to modulate the consequences of altered ocean chemistry. Given that physiological mechanisms used by organisms to confront acidification can be energetically costly, we explored the potential for food supply to influence the response of Olympia oyster (Ostrea lurida) larvae to ocean acidification. In laboratory experiments, we reared oyster larvae under a factorial combination of pCO2 and food level. High food availability offset the negative consequences of elevated pCO2 on larval shell growth and total dry weight. Low food availability, in contrast, exacerbated these impacts. In both cases, effects of food and pCO2 interacted additively rather than synergistically, indicating that they operated independently. Despite the potential for abundant resources to counteract the consequences of ocean acidification, impacts were never completely negated, suggesting that even under conditions of enhanced primary production and elevated food availability, impacts of ocean acidification may still accrue in some consumers.

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