RSS 1.0Pearson, Heidi
Heidi Pearson, PhD is Associate Professor of Marine Biology
Recent Submissions
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Climate SoundscapesCon Brio Chamber Series Presents CLIMATE SOUNDSCAPES Friday, November 18, 2022, 7:30 PM Kunéix Hidi Northern Light United Church Saturday, November 19, 2022, 2:00 PM Atrium at the APK State Library, Archives and Museum
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Whales in the carbon cycle: can recovery remove carbon dioxide?The great whales (baleen and sperm whales), through their massive size and wide distribution, influence ecosystem and carbon dynamics. Whales directly store carbon in their biomass and contribute to carbon export through sinking carcasses. Whale excreta may stimulate phytoplankton growth and capture atmospheric CO2; such indirect pathways represent the greatest potential for whale-carbon sequestration but are poorly understood. We quantify the carbon values of whales while recognizing the numerous ecosystem, cultural, and moral motivations to protect them. We also propose a framework to quantify the economic value of whale carbon as populations change over time. Finally, we suggest research to address key unknowns (e.g., bioavailability of whale derived nutrients to phytoplankton, species- and region-specific variability in whale carbon contributions).
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Integral functions of marine vertebrates in the ocean carbon cycle and climate change mitigationIn the last decade, the ocean has absorbed a quarter of the Earth’s greenhouse gas emissions through the carbon (C) cycle, a naturally occurring process. Aspects of the ocean C cycle are now being incorporated into climate change mitigation and adaptation plans. Currently, too little is known about marine vertebrate C functions for their inclusion in policies. Fortunately, marine vertebrate biology, behavior, and ecology through the lens of C and nutrient cycling and flux is an emerging area of research that is rich in existing data. This review uses literature and trusted data sources to describe marine vertebrate C interactions, provides quantification where possible, and highlights knowledge gaps. Implications of better understanding the integral functions of marine vertebrates in the ocean C cycle include the need for consideration of these functions both in policies on nature-based climate change mitigation and adaptation, and in management of marine vertebrate populations.
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Assessing the Behavioural Responses of Small Cetaceans to Unmanned Aerial VehiclesUnmanned Aerial Vehicles (UAVs), or drones, have recently emerged as a relatively affordable and accessible method for studying wildlife. Vertical Take-off and Landing (VTOL) UAVs are appropriate for morphometric, behavioural, abundance and demographic studies of marine mammals, providing a stable, nonintrusive and highly manoeuvrable platform. Previous studies using VTOL UAVs have been conducted on various marine mammal species, but specific studies regarding behavioural responses to these devices are limited and scarce. The aim of this study was to evaluate the immediate behavioural responses of common (Delphinus delphis) and bottlenose (Tursiops truncatus) dolphins to a VTOL UAV flown at different altitudes. A multirotor (quadcopter) UAV with an attached GoPro camera was used. Once a dolphin group was located, the UAV was flown at a starting height of 50 m directly above the group, subsequently descending 5 m every 30 s until reaching 5 m. We assessed three behavioural responses to a VTOL UAV at different heights: (i) direction changes, (ii) swimming speed and (iii) diving. Responses by D. delphis (n = 15) and T. truncatus (n = 10) groups were analysed separately. There were no significant responses of T. truncatus to any of the studied variables. For D. delphis, however, there were statistically significant changes in direction when the UAV was flown at a height of 5 m. Our results indicate that UAVs do not induce immediate behavioural responses in common or bottlenose dolphins when flown at heights > 5 m, demonstrating that the use of VTOL UAVs to study dolphins has minimal impact on the animals. However, we advise the use of the precautionary principle when interpreting these results as characteristics of this study site (e.g., high whale-watching activity) may have habituated dolphins to anthropogenic disturbance.
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Behavioral observations and stable isotopes reveal high individual variation and little seasonal variation in sea otter diets in Southeast AlaskaTwo complementary approaches were used to assess year-round variation in the diet of sea otters Enhydra lutris around Prince of Wales Island (POW) in southern Southeast Alaska, a region characterized by mixed-bottom habitat. We observed sea otters foraging to determine diet composition during the spring and summer. Then, we obtained sea otter vibrissae, which record temporal foraging patterns as they grow, from subsistence hunters to identify year-round changes in sea otter diets via stable isotope analysis of carbon (δ13C) and nitrogen (δ15N). We compared the stable isotopes from sea otter vibrissae and sea otter prey items that were collected during spring, summer, and winter. Overall, year-round sea otter diet estimates from stable isotope signatures and visual observations from spring and summer were dominated by clams in terms of biomass, with butter clams Saxidomus gigantea the most common clam species seen during visual observations. Our results indicate that these sea otters, when considered together at a regional level around POW, do not exhibit shifts in the main prey source by season or location. However, sea otter diets identified by stable isotopes had a strong individual-level variation. Behavioral variation among individual sea otters may be a primary driving factor in diet composition. This study provides quantitative diet composition data for modeling predictions of invertebrate population estimates that may aid in the future management of shellfisheries and subsistence hunting and the development of co-management strategies for this protected species.
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Examining the Role of Marine Mammals and Seabirds in Southeast Alaska’s Marine Ecosystem DynamicsPrimary producers are the foundation of marine food webs and require reliable nutrient sources to maintain their important role with ecosystems. While marine mammals and seabirds can play critical roles in marine nutrient cycling, their contributions are often overlooked. The fjord systems of Southeast Alaska support a high diversity of marine mammals and seabirds in addition to some of the most valuable fisheries in the US. Nonetheless, there is still relatively little known about nutrient sources and fluxes in this region which is a critical component of fisheries management. The goal of our study was to advance knowledge of the role of mammals and seabirds in marine nutrient cycling and to understand how changing marine mammal and seabird populations may alter ecosystem dynamics. We analyzed nutrient levels in marine mammal scat, seabird guano, and seawater samples collected in Berners Bay, Southeast Alaska, to determine the influence of marine mammals and seabirds on nearshore nutrient concentrations. Utilizing qualitative network models (QNMs), we then examined how a simulated Berners Bay ecosystem would respond to an increase in marine mammals, seabirds, and nutrients. Researchers are increasingly utilizing QNMs as a first step in the development of ecosystem-based fisheries management plans as their adaptable nature is well suited to address rapidly changing climatic conditions. Our direct nutrient measurements and QNM results indicate that marine mammals and seabirds have the potential to provide substantial contributions to marine nutrient concentrations in the region and that these valuable ecosystem services should not be overlooked.
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Recycling Attitudes and Behavior among a Clinic-Based Sample of Low-Income Hispanic Women in Southeast TexasWe examined attitudes and behavior surrounding voluntary recycling in a population of low-income Hispanic women. Participants (N = 1,512) 18–55 years of age completed a self-report survey and responded to questions regarding household recycling behavior, recycling knowledge, recycling beliefs, potential barriers to recycling (transportation mode, time), acculturation, demographic characteristics (age, income, employment, marital status, education, number of children, birth country), and social desirability. Forty-six percent of participants (n = 810) indicated that they or someone else in their household recycled. In a logistic regression model controlling for social desirability, recycling behavior was related to increased age (P,0.05), lower acculturation (P,0.01), knowing what to recycle (P,0.01), knowing that recycling saves landfill space (P,0.05), and disagreeing that recycling takes too much time (P,0.001). A Sobel test revealed that acculturation mediated the relationship between recycling knowledge and recycling behavior (P,0.05). We offer new information on recycling behavior among Hispanic women and highlight the need for educational outreach and intervention strategies to increase recycling behavior within this understudied population.
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CONSERVATION BENEFITS OF WHALE WATCHING IN JUNEAU, ALASKAAn increasing number of visitors to Juneau, AK, alongside a predictable population of humpback whales (Megaptera novaeangliae), has supported the substantial growth of its whale-watching indus- try. The industry provides benefits to the community through economic gains, while the experi- ence can foster environmental awareness and support for protection of whales and the environment. However, the sustainability of the industry could be jeopardized if increasing whale-watching vessel pressure affects the health of its resource, the whales. This study investigates whether participation in whale-watching tours in Juneau, AK can support conservation of whales and the environment. Participant knowledge, attitudes, intentions, and behaviors were obtained from 2,331 respondents in surveys before, after, and 6 months after a whale-watching tour during the 2016 and 2017 seasons. Following a whale watch, the percentage of participants that indicated whale watching as a knowl- edge source increased (p = 0.022), awareness of guidelines and regulations doubled (p < 0.001), and strong support for regulations increased (p = 0.016). Six months later, these responses remained significantly higher than before the whale watch. Despite knowledge of distance threshold increasing after a whale watch (p = 0.003) and 6 months after (p = 0.021), getting close to whales remained an important factor in a participant’s whale watch. Participants had a higher likelihood of strongly sup- porting guidelines and regulations if they indicated that boats can have a negative impact on whales or were aware of guidelines and regulations. Lastly, participants that acknowledged negative effects on whales from boats had higher overall proenvironmental attitudes. This study indicates that incor- porating messages that facilitate participant awareness of guidelines/regulations and the purpose of those measures can support conservation and protection of local whale populations through manag- ing participant expectations and ultimately encouraging operator compliance.
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Humpback Whale Movements and Behavior in Response to Whale-Watching Vessels in Juneau, AKThe whale-watching industry in Juneau, Alaska relies primarily on the presence of North Pacific humpback whales (Megaptera novaeangliae). To meet demands from the rapidly growing tourism industry, the number of whale-watching vessels in this region has tripled over the last 18 years. As a result, increased vessel presence could have negative effects on humpback whales, ranging from short-term behavioral disturbance to long-term impacts. The current humpback whale viewing regulations are outdated and may not be as effective as they were 18 years ago, when both the whale-watching industry and humpback whale population were smaller. The present study assessed how humpback whale movement and behavioral patterns were affected by (1) vessel presence and number of vessels present, and (2) time spent in the presence of vessels. The study also determined how humpback whale behavioral state transitions were affected by vessel presence. A total of 201 humpback whale focal follows were conducted during summer 2016 and 2017. Based on linear mixed effects models, whales in the presence (vs. absence) of vessels exhibited 38.9% higher deviation in linear movement (p = 0.001), 6.2% increase in swimming speed (p = 0.047) and a 6.7% decrease in inter-breath intervals (IBI) (p = 0.025). For each additional vessel present, deviation increased by 6.2% (p = 0.022) and IBI decreased by 3.4% (p = 0.001). As time spent in the presence of vessels increased, respiration rate increased (p = 0.011). Feeding and traveling humpback whales were likely to maintain their behavioral state regardless of vessel presence, while surface active humpback whales were likely to transition to traveling in the presence of vessels. These short-term changes in movement and behavior in response to whale-watching vessels could lead to cumulative, long-term consequences, negatively impacting the health and predictability of the resource on which the industry relies. Current formal vessel approach regulations and voluntary guidelines should be revisited to reduce vessel pressure and mitigate potential negative effects of this growing whale-watching industry.
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Oceanographic Determinants of the Abundance of Common Dolphins (Delphinus delphis) in the South of Portugal.Off mainland Portugal, the common dolphin (Delphinus delphis) is the most sighted cetacean, although information on this species is limited. The Atlantic coast of Southern Portugal is characterized by an intense wind-driven upwelling, creating ideal conditions for common dolphins. Using data collected aboard whale-watching boats (1929 sightings and 4548 h effort during 2010–2014), this study aims to understand the relationships between abundance rates (AR) of dolphins of different age classes (adults, juveniles, calves and newborns) and oceanographic [chlorophyll a (Chl-a) and sea surface temperature (SST)] variables. Over 70% of the groups contained immature animals. The AR of adults was negatively related with Chl-a, but not related to SST values. The AR of juveniles was positively related with SST. For calves and newborns, although the relationship between SST and AR is similar to that observed for juveniles, the effect could not be distinguished from zero. There was no relationship between Chl-a levels and the AR of juveniles, calves and newborns. These results corroborate previous findings that common dolphins tend to occur in highly productive areas demonstrating linkages between their abundance and oceanographic variables, and that this region may be a potential nursery ground.
