IntroductionPrimary production is essential for biological life to occur in aquatic ecosystems. These organisms create energy on their own thanks to photosynthesis. These autotrophs can be found at lower levels of food webs.
Primary production is what ties Arctic sea habitats together. Since little plants are living under the sea, primary production relies on the microscopic organisms. Despite the size, autotrophs are able to harvest enough sunlight and turns into energy for themselves. Primary producers become eaten by heterotrophs who also are eaten by even larger consumers in order to obtain energy. Through photosynthesis, they are the base for many food webs in the Arctic sea. As the Arctic sea ice continues melting, primary production is affected by temperature change, causing links in food cycle to change as well. With this ongoing problem, it could lead to trophic mismatches between primary producers and their fellow consumers.
II. Background Phytoplankton, microscopic creatures, are what make up majority primary production throughout the ocean. As stated above, they are able to obtain energy through the process of light reaction. Half of our world’s autotrophs are these microscopic organisms. The photonic zone, the thin sunlight layer of the ocean, is where the light reaction occurs. However it is difficult to observe as they cannot be seen from the Arctic surface. The cause for that is the chlorophyll that gives the phytoplankton their vibrant colors cannot penetrate through the intervening sea ice (Middleton 2017). Phytoplankton also need mineral nutrients in order for growth to take place.
Most nutrients is lost to the lower levels of the sea due to gravitational sinking and are replenished by the mixing of deeper waters. As such, availability of needed factors is limited but crucial for primary production throughout the ocean. Availability amount might adjust due to the climate, however there is the chance that unforeseen consequences can occur as well. As with any ecosystems that goes through adjustments, organisms learn must adapt in order to thrive in their ecosystem. How phytoplankton react plus adapt to the changing climate are topics that scientist have been doing studies on. Some microorganism could be just fine, and adapt to climate change quickly, while other types may not adjust well to the increase in temperature. Studies have shown that microorganisms adapting rapidly can lead to higher rates in photosynthesis – they can produce more energy, channel faster growth quota and better capacity for competition through other phytoplankton (Schaum 2017).
Because of that, climate change doesn’t seem to be as terrible as researchers say climate change is. Why is climate change considered as serious threat to aquatic environments? Even though some types of phytoplankton have been shown to be adaptable to the climate changes, scientist still do not know if it is the same for other types of aquatic microorganisms. III. Ice-Algae Because of the changing temperatures, Arctic sea-ice has been getting thinner for the past 30 years. This has opened up a new opportunity for researchers as Arctic algal blooms have been sighted at inhospitable regions where phytoplankton, as well as ice algae, throughout the past seven years since 2011. Just what are algal blooms? It is the algae population in big groups that are visible, mostly during early spring. The size and time of the bloom depends on the thickness of snow on the Arctic sea ice.
It also depends on how much sunlight penetrates through the sea ice. Normally ice-algae blooms are observed only in ice free waters. In 2011, however, an algal bloom was observed underneath the sea-ice covered region of the Chukchi Sea, which was thought to be uninhabitable for any phytoplankton. The discovery would start the many observations of the ice-algal blooms.
Research has evidence that temperature change in Arctic ice is indeed affecting the time the ice-algal blooms occur. Ice algae communities are found near the bottom of the ice and are wide spread across the Arctic ocean. They can also be found through columns under the ice and within brine channels. As the summer ice melts, ice-algae are discharge and sent to the freshening ocean surface. Ice algal begin to aggregate because of their sticky trait, and soon follow sedimentation. Ice algae must rely on other means in order to stay close to their sea-ice habitat in order to bridge the gap between the melting summer ice and the freezing during autumn. This leads to the ice-fauna being deprived from their food resource, but recent study by Lee (as cited by Assmay, 2013) shows that the thinning ice could lead to new habitats in the sea ice. Buoyant ice-algal aggregates have been observed, little is known about them.
What is the ecological importance of ice-algal aggregates during the melting season? One theory suggests that ice-algal aggregates seed the next spring bloom, but this has not been considered. Most current models that show the ice-algal production and biomass do not take account of the aggregations. Therefore they are underestimated despite the contribution ice algae give to the Arctic ocean ecosystem through primary production.IV. Introduction to Research Scientist know that the floating aggregates must have some sort of role in the Arctic ecosystem. What was that role? That’s what scientist have been trying to figure out. Scientist already know how vital ice algae are to its ecosystem.
They also know that the algal blooms can cause positive or negative effects. While not a new phenomenon, as there have been sightings in the past, there has been little data about the aggregates. Scientist wanted to know, just how important were the ice-algal aggregates during the melting season?Purpose: A previously stated, there is little data on the ice-algal aggregates. That was until the late summer of 2012. Two research cruises encountered large quantity of the buoyant aggregates during their trip in the Eastern Central Arctic. They were able to sampled and quantified the abundance, biomass, and production of the buoyant aggregates.
The first figure shows the records of each research cruise that observe the ice-algal aggregates. The first recorded cruise was the Centre for Ice, Climate and Ecosystem, (ICE 12 for short) with the RV Lance, labeled ICE 2012. The ICE 12 is a national competence center for ice and climate research and environmental regions. The second cruise, which had two markers, was the IceArc expedition ARK-XXVII/3 with the RV Polarstern, labeled IceArc 2012. Third cruise, which had two diamond markers, was the Russian North Pole drift station NP-23, labeled as NP-23 1977. The final marker was the Fram Expedition from 1893-1896, though it is labeled as Fram 1894, since that was when the ice-algal aggregates were first spotted. The scale on the graph represents the depth in meters, ranging from 500 meters to 4500 meters. The depth of the water is represented in a blue scale colour, white being the shallowest and dark blue being the deepest.
The broken line represents the ice edge at the end of July 2012.Three drift ice stations were also situated over the deep Arctic basin for the study areas. The first was occupied from July 26 to August 3 2012 during the ICE 12 cruise.
It was located at 82.5° N, 21° E, initially supposed to be north of Svalbard. The two shorter drift ice stations were occupied from 9 to 11 and 14 to 16 August respectively during the IceArc expedition. The coordinates were 82° N, 78° E for station Ice1 and 84° N, 78° E for station Ice 2 (Assmay et al 2012).
Methods: Three methods were used for getting samples of the ice-algal aggregates: trapping the aggregates in the ice hole, collecting the samples by scuba divers, and under ice video using an ROV, remotely operated vehicle. For the ICE 12 expedition, samples of seawater from five depths were collected, from the surface, 10, 50, 100m and Chl a (chlorophyll) maximum. Profiles of conductivity, temperature and depth were taken daily along with profiles of salinity and dissolved oxygen. These profiles were taken from technology created by Seabird Electronics.
Water samples were also taken where the sea ice was being pumped through in the same ice hole. Additional videos were taken that showed the ice-algal aggregates distributing in cracks and openings in the sea ice. The last thing that was sampled was biological sea ice thanks to an ice corer with an inner diameter of 9 cm. Once everything was collected, ice cores were cut into 10 to 20 cm thick sections and put into a polyethylene ziplock bags, stored dark and were melted directly at 4°C. The seawater and melted water samples were analyzed for chlorophyll, particulate organic compound and nitrogen. Ice-algal aggregates were the last samples to be collected for species identification that were used for iodine, Chl a, and transparent exopolymer particle analysis. Chemical and biological measurements were taken along with radiation measurements.
For the IceArc expedition, aggregated samples were mixed with seawater in order to be sub-sampled for POC, PON, pigments, and net primary production analysis (Assmay et al., 2013).Data Analysis: ROV transect analysis were used to detect the aggregates and the spatial distribution monitored thanks to a upward looking video system mounted on ROVs.
The ROV would navigated under the sea ice at ice stations Ice1 and Ice2 (Nicolaus M and Kaitlein C, 2013). The video images would directly identify the aggregate as images were registered according to the distance from the camera and the ice. Net primary production was used during the IceArc expedition, which is the rate of producing useful chemical energy.