Refugia under threat: Mass bleaching of coral assemblages in high‐latitude eastern Australia

By Victor Munoz, SRC MPS student

When hearing about the effects of climate change on coral reefs, most will likely think of damage from coral bleaching events (Goldberg & Wilkinson, 2004). Because bleaching has been associated with higher sea temperatures, coral reefs exposed to colder waters can sometimes be viewed as more resilient to rises in temperature (West & Salm, 2003). However, those reefs might be just as vulnerable to climate change, although in a different way to what we may think.

Figure 1. A coral colony (Photo by Daniel Hjalmarsson on Unsplash)

A recent study by researchers from the University of Queensland (Kim et al., 2019) has evaluated the performance of 8,000 coral colonies across 22 sites on the southeastern coast of Australia during the hot summer of 2016 (Figure 2). After taking several snapshots of the corals at each site, the scientists gave them a score depending on how bleached they were. They then compared the status of different coral species to environmental factors including the hottest months’ temperatures, the annual temperature fluctuation and the solar irradiance the corals were exposed to.

They found that overall, these environmental factors poorly explained the health of corals. Some species were very sensitive to changes in temperature, while others showed greater resistance to heat stress. Instead, it seems like those increased temperatures may significantly affect the diversity of corals in colder waters, with some hardy species becoming dominant over more “fragile” ones. This could have serious implications for the less resistant cold-water corals, as locations closer to the poles (where they could potentially grow) lack the environments to sustain them. The disappearance of those “fragile” corals could then lead to a reduction of the overall coral diversity, with potential repercussions on the complex functionality of the reef’s ecosystem as a hole.

Figure 2. The 22 sites included in the study, across Australia’s southeastern coast. (Source: Kim et al., 2019)

Popular discussions around climate-change tend to focus on the species that we may lose (Willis et al., 2008), but new appearances or dominance of other species in affected habitats has been just as much of a reality (Rahel & Olden, 2008). The different ways every ecosystems may be impacted by the effects of climate change still need to be studied in greater depth, but what should be understood is that no location is truly “safe” from its consequences and that changes in the environment will be witnessed from the equator all the way to the poles.

Work cited:

Goldberg, J., & Wilkinson, C. (2004). Global threats to coral reefs: coral bleaching, global climate change, disease, predator plagues and invasive species. Status of coral reefs of the world2004, 67-92.

Kim, S. W., Sampayo, E. M., Sommer, B., Sims, C. A., Gómez‐Cabrera, M. D. C., Dalton, S. J., … & Figueira, W. F. (2019). Refugia under threat: Mass bleaching of coral assemblages in high‐latitude eastern Australia. Global change biology. doi: 10.1111/gcb.14772

Rahel, F. J., & Olden, J. D. (2008). Assessing the effects of climate change on aquatic invasive species. Conservation biology22(3), 521-533.

West, J. M., & Salm, R. V. (2003). Resistance and resilience to coral bleaching: implications for coral reef conservation and management. Conservation Biology17(4), 956-967.

Willis, C. G., Ruhfel, B., Primack, R. B., Miller-Rushing, A. J., & Davis, C. C. (2008). Phylogenetic patterns of species loss in Thoreau’s woods are driven by climate change. Proceedings of the National Academy of Sciences105(44), 17029-17033.

Don’t Treat Your Marine Sediments Like Dirt

By Sander Elliot, SRC intern

Marine sediments are home to a surprisingly diverse ecosystem of global importance. Subseafloor Life and its Biogeological Impacts (D’Hondt et al., 2019) overviews this ecosystem and roles it plays. Marine sediments are often overlooked because they are removed from our daily lives. If one takes the time to look into these communities, they reveal themselves to be quite interesting. The very fact that life manages to survive in such a barren environment deprived of light and oxygen is fascinating on its own. However, they do more than survive – they thrive.

The article states that the total number of cells in marine sediments rivals that of those in terrestrial sediments as well as in the ocean as a whole. The cells in marine sediments tend to be necessarily smaller than their open ocean and terrestrial rivals, so the biomass of marine sediments is not close to that of soil or the ocean. Even so, that diversity of life in place that seems desolate is not to be taken lightly. These communities are also crucial to large scale biogeochemical cycles that have a huge effect on the planet as a whole. The article zeros in on five specific global effects of these communities.

Firstly, is the impact on the global redox budget. The ocean and atmosphere are oxidized by the burial of reducing material, and the marine sediment communities modulate this process, greatly affecting the redox state of the oceans. The exact extent of this affect is not entirely known, but figure 1 gives a broad outline of the various processes.

Figure 1. Various chemical processes in seafloor sediments that effect the global redox budget. (Source: D’Hondt et al. 2019)

The second outlined effect concerns the global sulfur cycle. This is also part of the redox budget, but the effects of the sulfur go beyond that. Sulfur is a vital to life, and marine sediments are a crucial step in the sulfur cycle. The third effect is on alkalinity and atmospheric CO2. The sulfuric reactions that effect the sulfur cycle also effect the alkalinity of the seawater. It turns out that the alkalinity of seawater is partially responsible for the partial pressure of CO2 in said water. The partial pressure determines how much CO2 is dissolved from the atmosphere into seawater. The carbon cycle is of great importance and interest in the midst of anthropogenic climate change. Figure 2 shows the sea surface gas exchange that is affected by the alkalinity of seawater. 

Figure 2. A simple carbon cycle diagram that shows the gas exchange between the ocean and atmosphere. (Source: Wikimedia Commons).

The fourth impact is on the global nitrogen cycle. Marine sediments are a sink for most of the fixed nitrogen in the ocean, so they are the reason that many ocean ecosystems are nitrogen limited. The final impact is on geological resources. Microbial communities have a great affect on marine resourses of economic interest, specifically hydrocarbons. These affects need to be studied further but are known to be present. Marine sediments play a broad and crucial role in the earth’s biochemical cycles. They are an evolutionary marvel and proof that we are intricately connected to even the most far removed places in the biosphere.

Works Cited

D’Hondt S, Pockalny R, Fulfer VM, Spivack AJ (2019) Subseafloor life and its biogeochemical impacts. Nat Commun 10:1–13. doi: 10.1038/s41467-019-11450-z

Pacific Heat Wave Reduces Nutritional Value of Pacific Sand Lance

By Olivia Schuitema, SRC intern

A marine heat wave known as “The Blob,” lasted from October 2013 to June 2016 in the North Pacific Ocean (von Biela, 2019). Heat waves can have detrimental impacts with both immediate and lasting effects on the marine environment. These warm patches can produce bottom-up disruptions in energy transfer (von Biela, 2019). “Bottom-up” refers to an ecological concept where changes in the lower energy levels in a food chain affect the upper levels of that food chain as well.

A pivotal species in the Prince William Sound ecosystem are the key forage fish the Pacific Sand Lance (Ammodytes personatus) (Abookire and Piatt 2005). Sand lance are indicator species (species that help infer conditions of a certain habitat) that have strong residency and make minimal migrations, tying them certain habitat conditions (von Biela et al., 2019). They have direct connections to species in the upper levels of pelagic food webs including sea birds, marine mammals and larger predatory fish, some of which have conservation status or are targeted for fisheries (von Biela, 2019). Changes in stocks of sea birds and marine mammals have been linked to shifts in abundance of forage fish stocks (Robards, 2002).

Figure 1. Varying total lengths (TL) of Sand Lance, Ammodytes personatus (Source: USGS.gov)

Evidence suggests that abundance and growth rates of sand lance are related with certain environmental conditions such as marine productivity and water temperature (von Biela et al., 2019). Researchers examined the nutritional condition of sand lance in Prince William Sound within the 5-year warming period of “The Blob.” Sand lance samples were collected in the field and measured for total length. Back in the laboratory, otoliths (inner ear structures in teleost fish that aid in balance and orientation) were extracted from fish samples, dried and examined under light to see growth rings (von Biela et al., 2019). Otolith layers are similar to tree rings; age of fish can be determined via counting the number rings. Otolith growth size is strongly correlated to somatic size within fish species (von Biela et al., 2019). Determining whole body energy required drying out fish samples, pressing the dried remains into a pellet and weighing the pellet (von Biela et al., 2019).

Figure 2. Otoliths with dark bands representing periods of slow growth during heat wave (left), and otoliths with more opaque regions representing fast growth after the heat wave subsided (right) (Source: von Biela 2019)

Past studies indicated that sand lance grew slowest and were least abundant in warmer areas compared to cooler areas (Robards et al. 2002). Results of this study support past findings; with the higher temperatures during the heat wave, there was a decrease in total length and a decline in whole body energy in sand lance samples (von Biela et al., 2019). This suggests that with warming temperatures, sand lance must expend higher metabolic energy in order to survive, resulting in smaller size and smaller energy stores. In this type of domino effect, the warming temperatures then resulted in lower chlorophyll levels and lower nutrient levels, further contributing to the smaller fish size. These results mean less energy moving up the trophic levels, affecting the health of entire marine food webs. Shifts in climate and environmental conditions could have harmful effects on key species of forage fish such as the sand lance (Abookire and Piatt 2005). This important study could be a predictive snapshot into our future as global temperatures continue to rise.

 

Works Cited

Abookire AA, Piatt JF. 2005. Oceanographic conditions structure forage fishes into lipid-rich and lipid-poor communities in lower Cook Inlet, Alaska, USA. Mar Ecol Prog Ser 287: 229−240

Robards MD, Rose GA, Piatt JF. 2002. Growth and abundance of Pacific sand lance, Ammodytes hexapterus, under differing oceanographic regimes. Environ Biol Fishes 64: 429−441

Von Biela, R. Vanessa, et al. 2019. Extreme reduction in nutritional value of a key forage fish during the Pacific marine heatwave of 2014−2016. Mar Ecol Prog Ser 613: 171-182

Foraging energetics and prey density requirements of western North Atlantic blue whales in the Estuary and Gulf of St. Lawrence, Canada

By Nicholas Martinez, SRC intern

Pelagic predators throughout the world’s oceans face the same challenge: foraging for food in an environment where much of their prey are available in clusters, centralized around specific areas of the ocean. For this reason, many pelagic predators have unique ways to find these limited resources, all the while adjusting these foraging techniques so as to maximize energy gained for every unit of energy expended.

In a world where oceanic ecosystems are facing rapid change, the need for more research and implemented protective measures is rising. Many marine animals have been documented as having shifted their foraging habits because of a rapid decline in available resources. These resources, which have supported countless generations of predators, are now facing serious threats to their population size. For this reason, studies of the foraging habits of large marine predators allows insight into the hunting grounds that still remain for these animals. Understanding how often these species forage for food allows scientists to determine the health of a specific population of that species. A 2019 paper from Guilpin and colleagues, “Foraging energetics and prey density requirements of western North Atlantic blue whales in the Estuary and Gulf of St. Lawrence, Canada”, focused on the foraging efficiency of the North Atlantic blue whale in a quickly changing oceanic environment.

 

Figure 1. The blue whale (Source: NOAA Photo Library/anim1754/Wikimedia Commons)

Foraging efficiency is a ratio that compares the rate of energy consumption to the rate at which energy is expelled so as to provide insight into an organism’s ability to store energy. Understanding a blue whale’s capacity to store energy is crucial because there is a direct correlation between the animal’s energy supply and its ability to reproduce. Using 10 depth-velocity tags attached to the whales, the scientists were able to monitor the foraging behaviors of blue whales in the St. Lawrence Estuary. While blue whales are the largest living organisms on the planet, their food supply consists small invertebrates called krill, which can be found in large populations throughout the study site. This food source exhibits spatial and temporal variations and thus requires a specialized foraging technique in order to maximize the whales net energy reserve.

 

Figure 2. “Predicted change in blue whale foraging effort with time of day in (a) feeding depth (m), (b) dive duration (s), (c) number of feeding dives, (d) number of lunges d−1, and (e) number of lunges h−1. Dark grey ribbons represent the 95% confidence intervals around the predicted response from generalized additive mixed models. Shaded areas are for nighttime (grey), dusk and dawn (light grey), and daytime (white). Points are data observations” (Source: Guilpin et al. 2019, p. 213)

Here, the researchers found that during the day, the tagged blue whales performed fewer but longer feeding dives than at other times of the day (Figure 1). This suggested that the blue whales invested in fewer but longer dives so as to maximize the amount of energy they could store by minimizing energy expenditure (Figure 2). In addition, the authors found that the whales were performing more lunges per dive (accelerating towards the surface, trapping any krill in their mouth as they momentarily breach), showing that even while the whales were not deep diving, they were still feeding.

 

Figure 3. “Relationship between energy expenditure during feeding dives for 3 blue whale sizes (22, 25, and 27 m length) and (a) dive duration (s) … (b) maximum dive depth (m) … and (c) number of lunges per dive” (Source: Guilpin et al. 2019, p. 214)

Although the whales were observed to feed throughout the day, this did not necessarily mean that they were consuming enough krill to achieve a neutral energetic balance. In fact, this study found that only 11.7 and 5.5% of Arctic and northern krill patches contained densities that could sustain a neutral energy balance for the blue whales. This could be due to a decline of krill populations via environmental impacts, and if so, poses a great threat to blue whale populations. This information emphasizes blue whales’ constant need to forage for high densities of krill in order to maintain neutral energy balance or maintain a healthy energy storage suitable for reproduction. The discoveries made in this paper may therefore help predict the effects of climate change on both predator/prey densities and may also offer insight on potential krill fisheries and how they may or may not affect blue whale populations.

Work cited

Guilpin M, Lesage V, McQuinn I, et al (2019) Foraging energetics and prey density requirements of western North Atlantic blue whales in the Estuary and Gulf of St. Lawrence, Canada. Mar Ecol Prog Ser 625:205–223. doi: 10.3354/meps13043

Preventing ecosystems from feeling clammy: what monitoring giant clam populations can tell us about human perseverance

By Maria Geoly, SRC Intern

Every aspect of our lives depends on the health of our natural resources. Clean water, nutrient rich soil, and access to timber are often considered humanity’s three most essential natural resources because they provide the four essential needs of living things: oxygen, water, food, and shelter. Often overlooked, however, is the crucial role that animals play in maintaining healthy resources. A healthy ecosystem is comprised of many different components (Figure 1), that work in a checks and balances system to maintain harmony.

Figure 1. A depiction of how different organisms contribute to the balance of natural systems. (Source: https://www.sciencelearn.org.nz/resources/143-marine-food-webs)

Populations and demographics of the species comprising an ecosystem can be considered in decision toward ecosystem and resource management. The human implications of these decisions, however, are not always considered in the same way. An example of this comes from the Tuamotu atolls of French Polynesia, presented in a study from Georget et al. (2019).

The Tuamotu atolls used to have some of the largest populations of giant clams (Tridacna maxima) on Earth (Figure 2). Over thirty years, researchers had monitored the number of giant clams in this area –the ocean floor was divided into many squares or “quadrants” and giant clam individuals were counted within random squares, to estimate the number of animals in that habitat.

Figure 2. Giant clams, Tridacna maxima. (Source: National Oceanic and Atmospheric Administration)

From 2005-2012, hundreds of giant clams started dying off very quickly due to unusual weather patterns. The drastic change in population was observed by the atolls’ residents, however the method used by researchers to monitor population did not. This methodology, known as “LIT-Q” testing, is an accurate way to measure abundant species, but as a species’ numbers decline, “BT” sampling methods, which use one very long but thin quadrant at a time, tend to be more precise.

As scientists realized their mistakes, they decided to try both methods at once, in old and new giant clam habitats, to see if their past data was incorrect. Computer simulations were used to make models of both data sets, and scientists found that each testing method gave different estimates for each site, with “BT” sampling being the most accurate.

This study is important because it recognizes the need for flexibility and reflexivity in scientific practice. In Tuamotu and other remote fisheries across the globe, fishing quotas are determined by the estimated population densities of a species. If the numbers are off, unsustainable policy could be written that may lead to overfishing, harming entire ecosystems and the people who rely upon them. As in the case of Tuamoto, scientists actively questioned if what they were doing was right and used creative problem solving to fix past mistakes. The revaluation of what once worked helped the area recognize that overfishing of giant clams was occurring, and fishing quotas have since changed to support the sustained health both the giant clams and of the reef systems supporting them.

Persevering through the daunting task of fixing such a big data mistake is hard, but the reward that comes with new understanding and solutions to large problems like overfishing is well worth the struggle. Tuamoto serves as a global example of why scientific methodology should often be questioned and reevaluated. The long-term benefits are ecologically worth it.

Work cited 

Georget S, Van Wynsberge S, Andréfouët S (2019) Understanding consequences of adaptive monitoring protocols on data consistency: application to the monitoring of giant clam densities impacted by massive mortalities in Tuamotu atolls, French Polynesia. ICES J Mar Sci 76:1062–1071. doi: 10.1093/icesjms/fsy189

Mapping the global network of fisheries science collaboration

By Julia Saltzman, SRC intern

Collaboration is something which we all learn about as children. We are taught to work together in teams, to share our toys, and that ideas are better when many individuals contribute to them. As science has become increasingly internationalized, scholars investigating the shifting spatial structure have posed questions to whether networks of research collaboration are actually expanding despite the argument that broad-based collaboration is crucial to solving the challenges ongoing with respect to fisheries (Syed, ní Aodha et al. 2019). The global marine catch is approaching its upper limit, the number of overfished populations and the indirect effects of fisheries indicate that fisheries management has failed to achieve any sort of sustainability. This failure is primarily due to the continued increase in harvest rates in response to global pressure for greater harvests and the inability to accurately model sustainable catch amounts. Nevertheless, fisheries provide the direct employment to about 200 million people and account for nearly 19% of the total human consumption of animal protein (Botsford, Castilla et al. 1997). Fisheries are a crucial resource, and the only way to promote comprehensive management is with collaboration on a global level.

Figure 1: The global marine catch is approaching its upper limit, the number of overfished populations and the indirect effects of fisheries indicate that fisheries management has failed to achieve any sort of sustainability.

With the imperativeness of this collaboration in mind scientists mapped and examined the landscape of scientific collaboration across fisheries science. The results were quite interesting, the collaboration has become more extensive and more intensive in various places. However, the fisheries science landscape is one where the centers of knowledge production and the collaboration across scientists is far more regional than global. The regional manner of collaboration in fisheries science is likely to limit the potential benefits of collaboration. Collaboration which is regionally limited in such a global field will have consequences such as preventing the innovation which is necessary to address the ongoing challenges within fisheries management. There are several different aspects of fisheries management which can be learned from this study. First and foremost, collaboration on a global level is crucial for sustainable fisheries management. This collaboration should manifest itself in several different ways whether it be direct collaboration between various fisheries, collaboration among scientists who work in different fisheries, and collaboration among governments and fisheries management organizations.

Figure 2: Collaboration is something which we all learn about as children. We are taught to work together in teams, to share our toys, and that ideas are better when many individuals contribute to them. As science has become increasingly internationalized, scholars investigating the shifting spatial structure have posed questions to whether networks of research collaboration are actually expanding despite the argument that broad-based collaboration is crucial to solving the challenges ongoing with respect to fisheries.

Works cited

Botsford, L. W., J. C. Castilla and C. H. Peterson (1997). “The Management of Fisheries and Marine Ecosystems.” Science 277(5325): 509.

Syed, S., L. ní Aodha, C. Scougal and M. Spruit (2019). “Mapping the global network of fisheries science collaboration.” Fish and Fisheries 20(5): 830-856.

Climate variability and life history impact stress, thyroid, and immune markers in California sea lions (Zalophus californianus) during El Niño conditions

By Isabelle Geller, SRC intern

There are many situations which may increase the level of stress in an animal – for example, not being able to eat enough food to meet energy demands or being in temperatures above or below a tolerable range they can. DeRango et al. (2019) aimed to study both of these factors with respect stress levels of California sea lions (CSL) (Figure 1). Specifically, the authors looked at impacts of environmental change (e.g. variability over the course of the study) and life history (e.g. pre-breeding and post-breeding stages – juvenile and adult – with different energy demands) on CSL during the El Niño of 2015-2016.

Figure 1: California Sea Lion (Rhododendrites [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]).

El Niño conditions are categorized by unusually warm and nutrient poor waters, typically in the Pacific region. DeRango and colleagues postulated that such unsuitable weather could change CSL hunting patterns, likely by pushing them further from shore resulting in larger energetic costs from the CSL. Likewise, for the adult male CSL during peak breeding season they would cease hunting to concentrate on the arduous breeding tenure.

To conduct the study, blood samples were taken from juvenile and adult CSL during October 2015/ October 2016 and March 2016/ August 2016 respectively (Figure 2). From the blood samples they analyzed stress hormones, glucose levels, thyroid hormones, immune markers and interactions between the HPA (hypothalamus, pituitary gland, and adrenals glands) axis; which they hypothesized would all be suppressed. However, the results were a bit different from expected:

  1. From 2015 to 2016 the glucose and stress hormone levels for juvenile and adult male CSL decreased.
  2. From 2015 to 2016 the thyroid hormones for juvenile and adult male CSL increased
  3. From 2015 to 2016 immunoglobin increased in juveniles but decreased for adult male CSL after breeding.

Figure 2: Timeline of events for the research of CSL. Types of CSL sampled: JUV = Juvenile, Ad M = Adult Male. Locations where CSL were sampled: ANI = Año Nuevo Island, California and Astoria, Oregon. (DeRango et al. 2019)

So, what do the results mean? The authors interpreted these trends as follows:

  1. From 2015 to 2016 the glucose and stress hormone levels for juvenile and adult male CSL decreased:

Since the juvenile sea lions had been facing chronic stress due to lack of food and the adult male sea lion due to sustained breeding period, they animals may have been unable to mount a normal stress response to the handling and drawing of blood. Additionally, due to a lack of nutrients for juvenile seals and the extremely energetically expensive reproductive process glucose (an important energy in organisms) decreased.

2. From 2015 to 2016 the thyroid hormones for juvenile and adult male CSL increased

To support energy intensive activities like hunting and breeding, thyroid function to increase during stressful activities like breeding and foraging. This may occur since the CLS were fasting, for aforementioned reasons, thus the stress hormone may not have had the same impact of suppression on the thyroid hormone as usual.

3. From 2015 to 2016 immunoglobin increased in juveniles but decreased for adult male CSL after breeding.

Immunoglobin, which is a markers for immune system cells, increased in juveniles likely due to greater exposure to pathogens, which would increase during El Niño events. However, immunoglobin decreased for adult male CSL, because reproduction and energetic limitations caused immunosuppression.

Looking to the future, this study has shown the impact of climate change on life history events and on the CSL population – this has contributed to an understanding of the marine mammal stress response to capture, and could help to create better research protocol for the CSL in the future.

Works cited

DeRango EJ, Prager KC, Greig DJ, et al (2019) Climate variability and life history impact stress, thyroid, and immune markers in California sea lions (Zalophus californianus) during El Niño conditions. Conserv Physiol 7:1–15. doi: 10.1093/conphys/coz010

Northward range expansion in spring-staging barnacle geese is a response to climate change and population growth, mediated by individual experience

By Gaitlyn Malone, SRC Masters Student

As climate change continues to rapidly alter environments, it is important to investigate how these changes impact the species that utilize these areas. When faced with these alterations, organisms will often have to adjust their behaviors in order to increase their survival. Animals that migrate long distances in order to meet their fitness needs are a great example of species that will often have to modify their behavior since they depend on different environments that are often far apart from one another and may change at varying rates. However, the means by which these organisms adjust can differ and there is very little knowledge about how many of these responses come about.

Figure 1: Barnacle Goose (Source: Dr. Raju Kasambe, Wikimedia Commons)

A recent study investigated how an increasing population of barnacle geese (Branta leucopsis) responded to the environmental changes occurring within their two spring-staging areas located in Helgeland and Vesterålen, Norway (Tombre et al. 2019). The southernmost staging area, located in Helgeland, had been traditionally used by the barnacle geese, however since the mid-1990s, an increasing number of geese had started to stage in Vesterålen, located 250 km north of Helgeland. From 1975 until 2017, the authors collected information on goose population numbers as well as weather conditions in order to determine the extent to which these characteristics contributed to the alteration in staging area use by both new recruits in the population and older individuals that altered their migratory strategy at a later stage in life. To determine whether climate change was a contributing factor to the diversity in population distribution, the authors estimated foraging conditions at both locations to see if differences in food conditions as well as increasing competition over resources due to population growth led to the change in staging area use.

Figure 2: Spring migrations routes and staging areas of barnacle geese (Source: Tombre et al. 2019)

Through their work, it was determined that while there was enhanced grass growth in Helgeland, the condition of foraging materials remained stable over time. However, in Vesterålen production of digestible materials increased, leading the authors to believe that the changing conditions in this area contributed to the change in the barnacle geese’s range. Additionally, it was determined that the population growth at Vesterålen occurred through to two different processes. First, during the initial years of colonization and after, young geese tended to switch to Vesterålen first and comprised the highest numbers within the flock. Secondly, it was also found that while older birds had a decreased probability of switching from Helgeland to Vesterålen, over time the probability increased for all ages. These findings suggest that barnacle geese use both social learning and individual experiences to adjust in their behavior and respond rapidly to climate change. These results are one of the first to portray the role that individual decisions play in population scale patterns and add to the growing knowledge on the importance of social learning in the development of migratory behaviors.

Works cited:

Tombre IM, Oudman T, Shimmings P, Griffin L (2019) Northward range expansion in spring ‐ staging barnacle geese is a response to climate change and population growth , mediated by individual experience. 1–14. doi: 10.1111/gcb.14793

The Negative Effects to Prevalent Plastic Pollution

By Delaney Reynolds, SRC intern

Plastic pollution has become one of the largest adverse impacts on marine life to date. In the last 70 years, plastic debris has become so prominent in layers of sedimentary deposits that it can be used as a primary indicator for the Anthropocene, a human-induced geological epoch (Puskic, et al. 2019). While plastic does technically break down, it only fragments into micro- and nano-plastics and thus never leaves the environment completely. These miniscule particles are commonly consumed by marine animals of all sizes ranging from plankton to whales. Seabirds such as albatross, petrels, and shearwaters have been found to have very high plastic ingestion rates due to their foraging strategies, as well as its various colors and odors that they find attractive. Ingesting plastic debris causes damage to lipid-derived fatty acids (FAs). FAs are warehoused in a variety of tissues for energy storage. Adipose tissues, connective tissue that also stores energy in the form of fat, contains triglycerides (TAG), main constituents in body fats, which are a vital energy source for juvenile birds.

Figure 1: Plastic pollution in Guanyin District, Taiwan (Source: Henry & Co. on Unsplash: https://unsplash.com/photos/cZpvuwwQQg0)

Researchers from the Institute for Marine and Antarctic Studies at the University of Tasmania explored how FA analysis could be used to investigate the impacts of seabird plastic ingestion on seabirds’ health. Roadkill or beach-washed deceased flesh-footed shearwater and short-tailed shearwater fledglings were collected on Lord Howe Island, New South Wales, Australia. Their body mass, wing length, and head + bill length were measured and plastic debris less than one millimeter in size were weighed. Adipose tissues were collected from breasts and FAs were extracted and analyzed with several statistical tests. The average number of plastic debris ingested was found to be 4.47 pieces weighing approximately 0.0760 grams for short-tailed shearwaters. The average number of plastic debris ingested was found to be 18.44 pieces weighing approximately 2.9277 grams for flesh-footed shearwaters. Although the research did not find a significant relationship between the mass of plastic, number of plastic debris present, and body mass, 37 different FAs were found in liver and muscle tissues between both species (Puskic, et al. 2019).

Figure 2: Differences in fatty acids between flesh-footed shearwater and short-tailed shearwater seabirds (Source: Puskic et al. 2019).

Discrepancies found between the FAs identified in the different species of shearwaters may be attributed to the turnover rate of FAs and lipid classes specific to tissues. The study concluded that flesh-footed and short-tailed shearwaters are, indeed, two distinct groups of one species based on FA composition. The FA composition of prey species likely drives the difference, as flesh-footed shearwaters are known to feed on mesopelagic fish and squid and short-tailed shearwaters are known to feed on krill and small cephalopods. These two different classes of prey have dramatically different FA levels, and this was found to be reflected in the FA outputs of the two different shearwaters.

Based on this study, fatty acid analysis can be used to explore how plastic pollution disrupts nutritional pathways and it was found that within the sample of shearwaters collected, there was no effect. These types of studies and tools will be imperative for use to manage and analyze the current and future effects of plastics on other species, especially marine, as anthropogenic-driven plastic pollution continues to become more prevalent in our world.

Works Cited:

Puskic, Peter S, et al. “Uncovering the Sub-Lethal Impacts of Plastic Ingestion by Shearwaters Using Fatty Acid Analysis.” Conservation Physiology, Oxford University Press, 16 May 2019, academic.oup.com/conphys/article/7/1/coz017/5489824.

Endangered Atlantic Sturgeon in the New York Wind Energy Area: implications of future development in an offshore wind energy site

By Enzo Newhard, SRC intern

The environmental benefits of renewable energy sources have been well established as the “pro green” discourse emphasizes the importance of eliminating our input of greenhouse gasses into the environment. The negative impact renewable energy development may have on the environment, however, has not been as thoroughly discussed. Burning fossil fuels releases harmful gasses into the atmosphere adding to the greenhouse effect and alters global ecosystem chemistries. Renewable sources’ generally have no waste product but due to their lower efficiency the installations need to take up a much larger area. However, it is largely unknown how some of these instillations could impact the environment in which they are installed especially ones in the ocean. A paper by Evan Corey Ingram, Robert M. Cerrato, Keith J. Dunton, and Michael G. Frisk, titled Endangered Atlantic Sturgeon in the New York Wind Energy Area: implications of future development in an offshore wind energy site, lays the groundwork for assessing the disturbances the development of an offshore wind farm may have on local populations of Atlantic Sturgeon.

The Atlantic Sturgeon is an endangered anadromous fish which is the species of concern for this paper as it is believed to be present in the waters slotted for the development of the New York Wind Energy Area (NY WEA). 133 Atlantic Sturgeon were caught and fitted with acoustic transmitters to record and track their movements in the WEA. Sturgeon were regularly detected throughout the study period except from July-September when abundance was low. Both temporal and spatial variations in their distribution were observed with the majority of detections occurring at the nearshore receivers except for periods of high abundance where the fish seemed more uniformly distributed throughout the WEA (Ingram et. al. 2019).

Figure 1. “Detection count (top panel) and unique transmitter count (bottom panel) of Atlantic Sturgeon detected on acoustic transceivers in the New York Wind Energy Area study site (Equinor, Lease OCS-A 0512). Transceivers are represented by increasing distance from shore; note that intervals are not equal.” (Source: Ingram et al. 2019)

Most of the research regarding sturgeon stocks has been done in riverine and estuarine environments, information about their population dynamics and foraging ecology in marine environments is largely unknown. This study provided a valuable baseline of sturgeon distribution and abundance in the future wind energy site and underscores the importance of long-term monitoring of offshore areas to enhance recovery efforts by locating important new habitats which have been underrepresented in current scientific literature.

Figure 2. “Monthly counts of unique Atlantic Sturgeon (represented by graduated symbols) detected at unique acoustic transceiver stations in the New York Wind Energy Area study site (Equinor, Lease OCS-A 0512) from November 2016 through January 2018. Monthly point values of average bottom temperature were compiled from transceiver metadata. The transceiver array operated throughout the entire course of the study with the exception of a single station indicated by (^) which was not recovered during the final download cruise; data for this station were unavailable for the months of August 2017–February 2018” (Source: Ingram et al. 2019)

Work Cited

E.C. Ingram, R.M. Cerrato, K.J. Dunton, M.G. Frisk 2019. Endangered Atlantic Sturgeon in the New York Wind Energy Area: implications of future development in an offshore wind energy site. Scientific Reports 9:12432