Active CMOL Research
South American Fur Seals and Sea Lions as Archivist of ENSO Effects off the Coast of Peru
Environmental fluctuations in the eastern Pacific Ocean are reflected in the tissues of one of its most vulnerable apex predators, the South American fur seal Arctocephalus australis and the South American sea lion Otaria flavescens. These large pinnipeds live along the Pacific coastline of South America and forage in the waters over the continental shelf. The coastal waters off Peru are a region of great environmental fluctuations due to periodic (every 2-7 years) El Niño-Southern Oscillation (ENSO) events, which result in ecosystem-wide food web changes. Pinniped body tissues reflect the incorporation of prey from the region; continuously growing tissues can provide a timeline of environmental data in an ecosystem where changes regularly occur and human instrumentation to measure such changes is sparse. Vibrissae (whiskers) are continuously growing tissues and fine resolution sampling along their length provides trophic information on weekly to monthly time scales over several years. Teeth are composed of annual growth layers which provide data on annual temperature and salinity changes where they and their prey reside. Stable carbon and nitrogen isotope ratios (δ13C and δ15N) found in vibrissae can be used to identify trophic relationships between pinnipeds and their prey found along Peru’s coastal margin. Stable isotopes of oxygen and carbon (δ18O and δ13C) in pinniped canine teeth can also be used to detect changes in sea surface temperatures and related primary production, both direct measures of ENSO events. Vibrissae have been collected and analyzed from adult female seals and adult male sea lions immediately following the 2009/2010 ENSO event. Preliminary data indicate distinct periods of decreased and increased primary production; these periods likely correspond to regional ENSO events impacting the food web. Continuance of a more comprehensive analysis of the South American fur seal and southern sea lion tissues collected from 2011 to 2017 will help identify productivity and trophic changes within the region and correlate those changes to climatic anomalies. The combined isotopic data from both tissues reveal how abiotic, ecosystem-wide changes influence the trophic dynamics and resultant survivability of the South American fur seal and sea lion.
Dietary Transfer of Heavy Metals in Manatees
The main focus of this project is heavy metal contamination in seagrass beds in South Florida and how this relates to the contamination being found in Florida manatees. Samples of the three major seagrass species in this area each month throughout 2017 are being collected. The grasses are analyzed for an array of heavy metals, including cadmium, iron, nickel, lead, zinc, and copper. The results will be used to make comparisons of metal concentrations across species, seasons, plant part, location, and proximity to potential sources of the metals. Concentrations between grasses found in the Port of Miami will be compared to those in Florida Bay to determine if the recent dredging activity may have increased the availability of heavy metals and therefore the concentrations in seagrass beds in the port. An investigation of other sources such as sewage discharge, agricultural or suburban runoff, and marine traffic. The results will be used to determine which metals and sources pose the greatest threat to Florida manatees.
Determining Humboldt Penguin Trophic Dynamics and Impacts on Embryo/Chick Survival through Stable Isotope and Heavy Metal Analyses
The Humboldt penguin, Spheniscus humboldti, is a Vulnerable species of penguin native to South America’s southwestern coast, with a range extending from Punta Aguja, Peru to Isla Metalqui, Chile. S. humboldti breeding sites were compromised by the proliferation of guano-collection initiatives during the 1800’s, which removed preferred nesting habitat. This anthropogenic impact, in addition to those of introduced invasive species and commercial harvest of prey fish species, is thought to have elicited significant population declines in S. humboldti. Due to these declines, large scale conservation efforts are now in place, one of which is an initiative based in Punta San Juan, Peru.
The Humboldt current system undergoes alternating blooms and depletions of production, triggered by El Niño-La Niña dynamics. ENSO (El Niño Southern Oscillation) events are linked to reductions in penguin prey abundance, which may lead to adult malnourishment and subsequently nest abandonment and elevated chick mortality. ENSO events can be recorded via stable isotope ratios, specifically those of C and N, found in various body tissues, including egg shell components, feathers and muscles. Through analysis of these tissues, trends in trophic dynamics can be identified and studied, and thus the effects of ENSO events on penguin trophics may be determined. Additionally, heavy metal concentrations of eggshell components and internal organs can be analyzed to assess environmental contamination. As the Humboldt current travels northward along the west coast of South America, there is a potential for heavy metal transportation from off-shore oil drilling sites distributed along the Chilean coastline to Peruvian waters, potentially resulting in biomagnification of heavy metals from low trophic level organisms to tertiary predators, such as Humboldt Penguins. Assessment of heavy metals in shell components may prove instrumental in determining the potential for selective maternal contaminant offloading into eggs in accordance with laying patterns, which may contribute to increased embryo/chick mortality. Parasitic Indicators of Foraging Strategies in Wading Birds in South Florida
Feeding ecology and trophic interactions of wading birds in South Florida will be explored through a combined analysis of stable isotope profiles and endoparasite communities. Stable isotopes broadly characterize the feeding preferences of individual birds while parasite communities reflect long-term trends in diet, feeding ecology, movements, and environmental changes. By characterizing the endoparasite fauna and combining it with stable isotope analysis, this project will provide novel information on wading bird feeding ecologies and trophic interactions.
Heavy Metals in Subsistence Harvest Bowhead Whale Baleen
Heavy metals are found naturally world-wide though human activity has amplified environmental concentrations. Potentially damaging concentrations are believed to have reached the Arctic realm - a relatively pristine region. Due to heavy metals’ potential to disrupt vertebrate physiology, analyses have been conducted on different species, including mysticete (baleen) and odontocete (toothed) whales. These studies utilized a variety of tissues (muscle, kidney, liver, blubber), but never baleen. Baleen, comprised of long, fine fibers, is the keratinous filter-feeding apparatus found solely in mysticete whales. Adult bowhead whales can have up to 370 plates per side, with fibers emerging from each plate. These fibers intertwine to form a dense, mat-like structure of inert tissue that aids in filtering minute invertebrates and occasionally tiny fish from the water column. A single baleen plate from a bowhead whale grows continuously and stores over 20 years’ dietary and environmental data. Heavy metal analysis of baleen plates will likely yield continuous timeline of contaminant concentrations in contrast to other body tissues which turnover. The detection of eight heavy metals (As, Cd, Cr, Cu, Hg, Pb, Se, Zn) in western Arctic bowhead whale baleen plates are expected across a half-century period (1947-1997) due to western Arctic heavy metal point sources (e.g. oil fields and mine locations), bowhead whale longevity (~200 years), and baleen’s success as a biosorbent. As the western Arctic population of whales migrates between the Bering, Chukchi, and Beaufort seas, the anticipated heavy metal concentrations are expected to represent these specific locations. Establishing baseline heavy metal concentrations both temporally and spatially will ultimately provide a guide for future comparisons in toxicological and environmental pollution research.
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Heavy Metals in North Pacific Marine Mammals
Three species of pinnipeds (harbor seal, northern fur seal, Steller sea lion) and a fissiped species (northern sea otter) have experienced dramatic declines since the 1970s due to anthropogenic events such as commercial fishing and hunting, vessel traffic, and pollution. The effects of environmental contamination on marine mammal health have led to concerns for population dynamics, yet information is still limited for contaminants such as heavy metals. The biosorption and bioaccumulation of these heavy metals may lead to disease and potentially death. A collection of archived vibrissae (whiskers) and body tissues was obtained from the four target species from the Bering Sea and throughout the Gulf of Alaska from 1990 through 2013. This study seeks to establish a dataset of up to twelve heavy metal (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se, V, Zn) concentrations using atomic absorption flame. The results of these datasets can be compared with future sampling efforts to determine if heavy metal concentrations vary over time for each of the four target species, ascertain a relationship among the concentrations for each body tissue type, and provide an important understanding of the potential role of heavy metals in marine mammal population dynamics.
Does the apple fall far from the tree? Assessing maternal transfer in sea turtles.
Assessing maternal transfer of stable isotopes and heavy metals of sea turtles that nests in Broward County. Assessment will be done by analysis of sea turtle egg shells and deceased hatchlings of loggerhead (Caretta caretta), green (Chelonia mydas), and leatherback (Dermochelys coriacea). Goal of the experiment will be to create a baseline of stable isotope and heavy metal load in hatchlings. It is hypothesize that due to the input of the mother sea turtle, stable isotope and heavy metal profiles should reflect the mother's diet. Analysis of carbon and nitrogen stable isotope with heavy metals should provide information on mother's feeding habits.
Northern Fur Seals as Monitors of Production Change
This study found evidence of intermittent, multi-year residency periods in northern fur seals (Callorhinus ursinus) using stable isotope ratios in vibrissae and canine teeth. Northern fur seals migrate from the Bering Sea during summer months to lower latitudes and slightly warmer waters of the northeastern Pacific Ocean and California Current in the winter. To determine the length of time spent away from the Bering Sea, growth rate was estimated using the covarying oscillations δ13C and δ15N, estimated to be 0.09 mm/day. The δ13C and δ15N in vibrissae from 30 male fur seals showed a minimum of 13 separate periods of stable covariance covering 3.25+ cm, indicating at least 1 year in warmer, less productive waters of the northeastern Pacific Ocean. The vibrissae isotope ratios were used in conjunction with δ18O from tooth dentin growth layer groups of 20 male northern fur seals; the showed significant enrichment in δ18O in 50% of the animals at age 1-2 years, which indicates extended periods of time spent in lower latitudes in the North Pacific Ocean, as δ18O is typically enriched in warmer, less productive waters. Significant changes in δ18O were found to be ~ 0.2‰ enrichment per 10º south latitude, while longitude was found to have 0.2‰ enrichment per 50˚east longitude which shows that latitudinal changes, those related to the southerly migration from the Bering Sea to the northeastern Pacific Ocean, are a stronger factor in the shifts in dentinal δ18O than longitudinal shifts. These intermittent periods of occupation are important when estimating population abundance of northern fur seals, especially pups and juveniles.
Determining the Potential of Ikaite Crystals to Form in Sea Ice
Ikaite, a rare and highly unstable hexaydrate of calcium carbonate was recently discovered forming naturally in both Arctic and Antarctic sea ice. After discovering ikaite crystals forming in frozen water samples from Atlantic seawater off the coast of South Florida, a number of water samples were collected from other sites to determine the range of conditions in which ikaite can form in ice. Currently, artificial sea water samples, created in the lab, are being used to test for ikaite formation, allowing for more precise control over conditions that may help or inhibit crystal formation.
Effects of Age, Mass, and Maternal Strategies on Oxygen Store Development in Phocid and Otariid Seals Pinnipeds rely on an unique physiology of oxygen storage and utilization while diving and foraging. The mechanisms for oxygen (O2) storage are not fully developed at birth, but transition during the period from nursing to first independent foraging. Therefore, pinniped pups must spend a portion of their lives terrestrially. This period comes in the form of a terrestrial post-weaning fast (PWF), which is crucial for rapid physiological maturity, or a prolonged lactation period that allows for slower maturity over a longer period of maternal dependence of pups to juveniles. Among the pinnipeds, the family Phocidae, true seals, have exceptional diving capabilities. Phocids have large oxygen reserves which result in prolonged diving activity. The family Otariidae, eared seals, tend to make substantially shorter and shallower dives, indicating they have less oxygen reserves. Oxygen stores that must be developed for adequate diving and foraging include increased hemoglobin, hematocrit, and myoglobin. The rate of oxygen development may be affected by inter-species differences in life history strategies, which in turn can affect the behavior and diving capacity of juvenile seals. For example, the different maternal strategies that phocids and otariids exhibit with their pups that affect their nursing and weaning. These different strategies provide insight into the ontogeny and O2 store development of pups throughout the weaning period and may correlate to the weaning period necessary for pups to gain sufficient oxygen stores. Comparing the development of oxygen stores among various species within each family will provide insight on the physiological development of pinniped pups and their diving ability.
Northeastern Pacific Ocean Paleoceangraphy Production Changes through the Holocene
Changes in marine production play a key role in determining the trophic structure of the northeastern Pacific Ocean. This is a region of great environmental fluctuations due to recent, historical, and paleo-environmental variability recorded throughout the Holocene. These fluctuations are recorded in the bone collagen of the marine mammals that reside in these waters. Archaeofaunal remains of cetacean and pinniped species from Unalaska Island, Alaska are used as a proxy for marine production changes throughout the Holocene. Marine mammal remains from four previously excavated archaeological deposits span a time period from 5,500 BP to 200 BP. Stable carbon and nitrogen isotope ratios (𝛿13C and 𝛿15N) derived from marine mammal bone collagen correlates to changes in marine production levels as well as changes in food web dynamics. Preliminary data indicate periods of increased and decreased primary production, likely corresponding to environmental fluctuations impacting the food web of that time period. A more comprehensive analysis of the archaeofaunal remains will help identify productivity and trophic level changes within the region and to correlate those changes to natural and/or anthropogenic climatic anomalies.
Foraging Domains of Salmon Species in the Gulf of Alaska
The foraging habits of Pacific salmon during the oceanic stage of development remain largely unknown. In July 2001, the Japanese research vessel, Oshoru Maru, collected salmon, squid and zooplankton samples at six stations along the 145°W longitude line near the coast of Alaska (56°N) to Ocean Station Papa (50°N) in the Gulf of Alaska. Six salmon species, Berryteuthis squid and several major taxa of zooplankton were analyzed for stable carbon (d13C) and nitrogen (d15N) isotope ratios. Through this research it was inquired how abiotic variability such as major current shifts could influence biotic factors, feeding dynamics and spawning triggers.
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