23 research outputs found
Applying a Macro Lens to Microplastics: Modeling Microplastic Ingestion Risk to Humpback Whales in the Chesapeake Bay
No full textPlastic waste is an increasing threat to marine environments, with an estimated 1.2-2.4 million metric tones of waste entering marine systems through rivers yearly. Plastic debris can fragment into smaller particles, classified as microplastics (particles \u3c 5mm), due to weathering, oxidation, and other processes. When consumed by an organism, MPs can be retained in the stomach, resulting in false satiation, and may lead to translocation that creates damage at the cellular level. Filter feeding megafauna such as humpback whales are at risk of directly ingesting MPs suspended in the water column and may accumulate particles indirectly by consuming contaminated prey. Based on previous MP ingestion risk assessments, fish-feeding humpback whales in the California Current consume approximately 200,000 pieces of MP per day. While MP ingestion risk has been documented for humpback whales in the California Current, less is known about the risk in the Mid-Atlantic, specifically within the Chesapeake Bay. Determining exposure route and the extent of bioaccumulation are important first steps to assessing risk for individuals and populations. I will model microplastic ingestion risk to humpback whales in the Chesapeake Bay by incorporating CATS (Customized Animal Tracking Solutions) tag data, feeding rates, prey density, and empirical values of MP contamination in collected prey and water column samples. I will use heat assisted chemical digestion and filtration methods to extract the MPs in these samples. I will photograph and record size, color, and type (e.g. fragments, foams, and fibers) of the isolated MPs and perform Fourier-Transform Infrared Spectroscopy (FTIR) analysis to identify their source. Studying MPs across trophic levels is important for highlighting potential entry pathways for marine debris, critical for protecting natural resources, and guiding informed management implementation
Filter Feeding Structures of the Sabellid Marine Annelid Parasabella microphthalmus
No full textFilter-feeding organisms play a critical role in estuarine and coastal ecosystems, providing ecosystem functions and services, such as regulating water quality and nutrient cycling. The increase in frequency and intensity of extreme climatic events is expected to impact filter-feeding invertebrates by affecting their metabolism, altering their feeding behavior, and impairing feeding mechanisms, including particle capture and transport. This highlights the importance of characterizing filter-feeding structures and functions as a key first step toward understanding their vulnerability to climate change. We propose to study the feeding structures, behavior, and biomechanics of the filter-feeding, tube-dwelling feather duster worm Parasabella microphthalmus (Annelida). Marine annelids are an ecologically important, yet under-studied group in climate change biology. They exhibit remarkable diversity and adaptability, as evidenced by their varied feeding strategies, and serve an important role as disturbance indicators in human-impacted habitats. We will use Scanning Electron Microscopy (SEM) to study the ultrastructure of the feeding parts of P. microphthalmus. In addition, we will quantify and characterize the morphometrics of the body and mouth parts of the worm and their allometric relationships. This will be the first morphological study of the filter-feeding structures of this species and will provide the necessary background for further studies on the efficiency of the filter feeding mechanisms of this species under climate change scenarios
Splitting Hairs: Biomechanics of Gray Whale (Eschrichtius robustus) Baleen
No full textRorqual whales (Mysticetes, Cetacea) use baleen, a filtration structure attached to the upper jaw, to retain prey from water during filter feeding. Baleen is the general term used for the keratin filter of all mysticetes, and refers to the complete structure of the Zwischensubstanz, connective papillae, major baleen plates, minor baleen plates, and baleen fringes. Rorquals lunge filter-feed, engulfing enormous masses of both prey and water. Gray whales (Eschrichtius robustus) use a unique method of suction filter-feeding, in addition to lunge filter-feeding. Gray whales scrape their heads and baleen against the substrate, fluidizing mud and sand to suck in their prey. Gray whale baleen must endure repeated collisions with rough substrate, while withstanding the forces of gallons of prey and water. To better understand the deformation of gray whale baleen, we recorded morphological measurements and performed three-point bend tests to record max load values on baleen plates from 18 gray whales in four demographics categories: male adults, female adults, male subadults, and female subadults. We found significant morphometric differences (p \u3c 0.001) in plate length, plate width, plate fringe diameter, plate lingual thickness, major spacing and minor spacing between the groups. The strongest factor in separating the baleen from one group to another was flexural stiffness (EI), which was consistently higher in male adults than in other demographic groups. Differences in the morphological and material of baleen properties point to variance in behavior and function throughout a gray whale’s lifespan. Future investigation into how the location of a baleen plate in the mouth (anterior/posterior, right/left) relates to its material function may demonstrate behavioral and functional differences in a single individual
Baleen–Plastic Interactions Reveal High Risk to All Filter-Feeding Whales from Clogging, Ingestion, and Entanglement
No full textBaleen whales are ecosystem sentinels of microplastic pollution. Research indicates that they likely ingest millions of anthropogenic microparticles per day when feeding. Their immense prey consumption and filter-feeding behavior put them at risk. However, the role of baleen, the oral filtering structure of mysticete whales, in this process has not been adequately addressed. Using actual baleen tissue from four whale species (fin, humpback, minke, and North Atlantic right) in flow tank experiments, we tested the capture rate of plastics of varying size, shape, and polymer type, as well as chemical residues leached by degraded plastics, all of which accumulated in the baleen filter. Expanded polystyrene foam was the most readily captured type of plastic, followed by fragments, fibers, nurdles, and spherical microbeads. Nurdle and microbead pellets were captured most readily by right whale baleen, and fragments were captured by humpback baleen. Although not all differences between polymer types were statistically significant, buoyant polymers were most often trapped by baleen. Plastics were captured by baleen sections from all regions of a full baleen rack, but were more readily captured by baleen from dorsal and posterior regions. Baleen–plastic interactions underlie various risks to whales, including filter clogging and damage, which may impede feeding. We posit that plastics pose a higher risk to some whale species due to a combination of factors, including filter porosity, diet, habitat and geographic distribution, and foraging ecology and behavior. Certain whale species in specific marine regions are of the greatest concern due to plastic abundance. It is not feasible to remove all plastic from the sea; most of what is there will continue to break into ever-smaller pieces. We suggest that higher priorities be accorded to lessening humans’ dependence on plastics, restricting entry points of plastics into the ocean, and developing biodegradable alternatives
Video_1_Evidence for Size-Selective Predation by Antarctic Humpback Whales.MP4
No full textAnimals aggregate around resource hotspots, but what makes one resource more appealing than another can be difficult to determine. In March 2020 the Antarctic fjord Charlotte Bay included >5× as many humpback whales as neighboring Wilhelmina Bay, a site previously known for super aggregations of whales and their prey, Antarctic krill. We used suction-cup attached bio-logging tags and active acoustic prey mapping to test the hypothesis that whale abundance in Charlotte Bay would be associated with higher prey biomass density, and that whale foraging effort would be concentrated in regions of Charlotte Bay with the highest biomass. Here we show, however, that patch size and krill length at the depth of foraging were more likely predictors of foraging effort than biomass. Tagged whales spent >80% of the night foraging, and whales in both bays demonstrated similar nighttime feeding rates (48.1 ± 4.0 vs. 50.8 ± 16.4 lunges/h). However, whales in Charlotte Bay foraged for 58% of their daylight hours, compared to 22% in Wilhelmina Bay, utilizing deep (280–450 m) foraging dives in addition to surface feeding strategies like bubble-netting. Selective foraging on larger krill by humpback whales has not been previously established, but suggests that whales may be sensitive to differences in individual prey quality. The utilization of disparate foraging strategies in different parts of the water column allows humpback whales to target the most desirable parts of their foraging environments.</p
Video_2_Evidence for Size-Selective Predation by Antarctic Humpback Whales.MP4
No full textAnimals aggregate around resource hotspots, but what makes one resource more appealing than another can be difficult to determine. In March 2020 the Antarctic fjord Charlotte Bay included >5× as many humpback whales as neighboring Wilhelmina Bay, a site previously known for super aggregations of whales and their prey, Antarctic krill. We used suction-cup attached bio-logging tags and active acoustic prey mapping to test the hypothesis that whale abundance in Charlotte Bay would be associated with higher prey biomass density, and that whale foraging effort would be concentrated in regions of Charlotte Bay with the highest biomass. Here we show, however, that patch size and krill length at the depth of foraging were more likely predictors of foraging effort than biomass. Tagged whales spent >80% of the night foraging, and whales in both bays demonstrated similar nighttime feeding rates (48.1 ± 4.0 vs. 50.8 ± 16.4 lunges/h). However, whales in Charlotte Bay foraged for 58% of their daylight hours, compared to 22% in Wilhelmina Bay, utilizing deep (280–450 m) foraging dives in addition to surface feeding strategies like bubble-netting. Selective foraging on larger krill by humpback whales has not been previously established, but suggests that whales may be sensitive to differences in individual prey quality. The utilization of disparate foraging strategies in different parts of the water column allows humpback whales to target the most desirable parts of their foraging environments.</p
Baleen whale inhalation variability revealed using animal-borne video tags
No full textEmpirical metabolic rate and oxygen consumption estimates for free-ranging whales have been limited to counting respiratory events at the surface. Because these observations were limited and generally viewed from afar, variability in respiratory properties was unknown and oxygen consumption estimates assumed constant breath-to-breath tidal volume and oxygen uptake. However, evidence suggests that cetaceans in human care vary tidal volume and breathing frequency to meet aerobic demand, which would significantly impact energetic estimates if the findings held in free-ranging species. In this study, we used suction cup-attached video tags positioned posterior to the nares of two humpback whales (Megaptera novaeangliae) and four Antarctic minke whales (Balaenoptera bonaerensis) to measure inhalation duration, relative nares expansion, and maximum nares expansion. Inhalation duration and nares expansion varied between and within initial, middle, and terminal breaths of surface sequences between dives. The initial and middle breaths exhibited the least variability and had the shortest durations and smallest nares expansions. In contrast, terminal breaths were highly variable, with the longest inhalation durations and the largest nares expansions. Our results demonstrate breath-to-breath variability in duration and nares expansion, suggesting differential oxygen exchange in each breath during the surface interval. With future validation, inhalation duration or nares area could be used alongside respiratory frequency to improve oxygen consumption estimates by accounting for breath-to-breath variation in wild whales
Fast and Furious: Energetic Tradeoffs and Scaling of High-Speed Foraging in Rorqual Whales.
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