Ice melting
Despite this be a factor with a considerable variability throw the years and different places, the fact is that in average Antarctica has suffering with losses of sea ice extend, duration and thickness (20), and it’s predict to future years this effect of global changes might be amplified (1). The ice melting can increase production and consequently krill blooms in adjacent areas for a short time, as more nutrients available, process that occurs every summer (5). The problem is life cycle of krill is highly dependent of physics conditions and sea ice (16), and the most dependent stage is recruitment, in other words, the number of juveniles specimens that develops until be able to reproduction (17). Krill larvae needs sea ice for food, protection and transport and they are more vulnerable than adults as can’t store energy for long periods, so this impact on recruitment may become a dominant problem for krill population (11).
High temperatures on the ocean
Studies show that temperature has increasing in most areas on the ocean, and Antarctic Circumpolar Current is warming above the average (Fig 3) (3)(10). As krill is adapted to stable low temperatures, this is expected to have a huge impact on physiology, behavior and distribution of individuals, affecting the population (2). Again larvae is expect to be the most impacted, as adults can migrate easier to deeper waters. This migration can affect air breathing animals that feed from krill. Although may some adults krill take advantage as increase of metabolism taxa, for the population increase on temperature is a have a bad effect, and probably will restrict it more to south (9).
Ocean acidification
Ocean acidification (OA) is one of bigger problems faced by krill, as affect this animal by many ways. First of all, the cold waters of southern ocean, region with high concentration of Antarctic Krill, are expect to suffer more impacts with OA, as CO2 has high solubility in colder waters. This drop on pH will directly affect krill exoskeleton, made by CaCO3, as development of larvae, physiology and growth. Indirectly, this is affect the phytoplankton, base of food chain, what affects all upper consumers, such krill and above (6).
Despite this be a factor with a considerable variability throw the years and different places, the fact is that in average Antarctica has suffering with losses of sea ice extend, duration and thickness (20), and it’s predict to future years this effect of global changes might be amplified (1). The ice melting can increase production and consequently krill blooms in adjacent areas for a short time, as more nutrients available, process that occurs every summer (5). The problem is life cycle of krill is highly dependent of physics conditions and sea ice (16), and the most dependent stage is recruitment, in other words, the number of juveniles specimens that develops until be able to reproduction (17). Krill larvae needs sea ice for food, protection and transport and they are more vulnerable than adults as can’t store energy for long periods, so this impact on recruitment may become a dominant problem for krill population (11).
High temperatures on the ocean
Studies show that temperature has increasing in most areas on the ocean, and Antarctic Circumpolar Current is warming above the average (Fig 3) (3)(10). As krill is adapted to stable low temperatures, this is expected to have a huge impact on physiology, behavior and distribution of individuals, affecting the population (2). Again larvae is expect to be the most impacted, as adults can migrate easier to deeper waters. This migration can affect air breathing animals that feed from krill. Although may some adults krill take advantage as increase of metabolism taxa, for the population increase on temperature is a have a bad effect, and probably will restrict it more to south (9).
Ocean acidification
Ocean acidification (OA) is one of bigger problems faced by krill, as affect this animal by many ways. First of all, the cold waters of southern ocean, region with high concentration of Antarctic Krill, are expect to suffer more impacts with OA, as CO2 has high solubility in colder waters. This drop on pH will directly affect krill exoskeleton, made by CaCO3, as development of larvae, physiology and growth. Indirectly, this is affect the phytoplankton, base of food chain, what affects all upper consumers, such krill and above (6).
Fig 3 - Summer Surface temperature anomaly (Celsius degrees) (Meredith & King, 2005)