Undergraduate Research and Creativity URECA 2008-2009

Karen Bubelnik and Kamazima Lwiza, School of Marine & Atmospheric Sciences — Characteristics of extreme temperatures in coastal waters of North America

This study uses daily sea surface coastal temperature records from four stations from the west coast and one station from east coast in USA to examine characteristics of temperature extremes in coastal waters. Quantiles of winter and summer temperatures from 1945 to 2006 are used to examine seasonal extremes and their statistical characteristics. More than 70% of the interannual variability in the extremes is driven by the interannual variations in the mean temperature, and the probability distribution functions are approximately invariant with time. The wavelet analysis reveals significant peaks at periods of 3, 4-6, 16-20 years for winter extremes. The energy for summer extremes is significant at 2-3 and 4-8 years between 1920 and 1940. Then the system goes into a quiescent period between 1940 and 1955 followed by peaks which operate between 3-6 and 14-18 years. Processes operating at long time scales (14-18 years) seem to be transcontinental because they exist on both coasts at about the same time. Short-time scale (<5 years) processes seem to be driven by local processes on each coast and each station. It seems that large-scale ocean variations, e.g., Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), and Arctic Oscillation (AO) seem to exert strong influence on the coastal extreme temperatures. However, their exact individual contributions to the extreme variability are not clear because their frequencies are very similar. The stationarity of the centered quantiles of the extremes implies that for each station we can use one extreme value distribution function for each season. This would be useful for predictions of extreme temperatures of future climatic scenarios.

 

Cory Clifton and Brian Colle, Institute for Terrestrial & Planetary Atmospheres, School of Marine & Atmospheric Sciences — Inner vortex evolution of Hurricane Ophelia (2005)

During the past 20 years, the short-term (1-3 day) forecasts of tropical cyclone intensity have not significantly improved. Unlike track forecasts, which have benefited from improved large-scale atmospheric flow forecasts from computer models, intensity changes within hurricanes remain poorly understood and modeled. High-resolution simulations of the hurricane’s inner core, which are necessary for understanding intensity changes, are hampered by limits of computer power, a lack of detailed observations, and an incomplete understanding of inner core dynamics. One of the most difficult dynamical problems is the Eyewall Replacement Cycle (EWRC), which is difficult to predict because its genesis is not well understood. To gain further understanding of EWRCs, as well as general inner core dynamics, the Hurricane Rainband and Intensity Change Experiment (RAINEX) took place in 2005, which conducted numerous WP-3D weather research aircraft missions into hurricanes Katrina, Rita, and Ophelia. Of the three storms, Ophelia on 11-12 September 2005 was the weakest, never exceeding category 1 strength. However, Ophelia did have an interesting EWRC, which was investigated using a unique set of high resolution observations.

This study examines the inner vortex evolution of hurricane Ophelia. Aircraft tail and lower fuselage radar as well as flight-level temperature, wind, and moisture data were analyzed during an EWRC as the storm approached the southern North Carolina coast. Airborne Doppler radar illustrated the detailed flow and convective rainband evolution around the inner eye wall. This aircraft data, augmented with satellite and surface measurements provided a comprehensive dynamical picture of the inner core of the system.

Ophelia’s eye wall went through rapid evolution for a 24h period on 11-12 September 2005. The inner core interacted with an outer rainband located about 100 km from the center, which was the genesis of the EWRC. During this process, the central area of convection disappeared around the eye wall, while the outer rainband eventually wrapped around the entire storm, becoming a large, new eyewall located about 80 km from the center. Meanwhile, the flight-level winds and pressures showed the development of secondary wind maxima associated with a EWRC. This vortex evolution may provide clues to the dynamics of other future storms in which the inner core is replaced by an outer rainband.

 

Seanna Forrester and Daniel Knopf, School of Marine & Atmospheric Sciences — The effect of long chain fatty acid/fatty alcohol monolayers on ice nucleation from aqueous salt droplets

Future global climate change can have a significant impact on society and the biosphere. Therefore, it is important to assess the factors influencing climate. Atmospheric constituents such as CO₂ and aerosol particles can significantly affect the global radiative budget and thus climate. Whereas the effects of greenhouse gases are well known, the effects of aerosols on the radiative budget remain highly uncertain. Actual modeling suggests that aerosol particles may cool the atmosphere by directly scattering incoming ultraviolet radiation and absorbing terrestrial radiation, and indirectly by acting as cloud condensation nuclei and ice nuclei, changing the radiative properties of clouds. In the upper troposphere, temperatures promote the formation of ice leading to the formation of cirrus clouds that can reflect solar radiation and absorb terrestrial radiation.

The oceans are a major source of aerosol particles. It has been shown that many of these natural aerosols are comprised of sea salt and surface active amphiphilic organic compounds. These organic compounds can act as ice nuclei, altering the freezing temperature of the aerosol particle. Only a few studies have explored the effects of such monolayers acting as heterogeneous ice nuclei, and have shown that the monolayers induce freezing on pure water droplets at higher temperatures.

Here, we examine the effect of several different long chain organic molecules on ice nucleation from aqueous salt droplets. First we determine the monolayer properties by measuring pressure-area isotherms and the equilibrium spreading pressure (ESP) of four different organic surfactants on 5 wt% and 20 wt% aqueous NaCl solutions. This is done using a 612-D model Langmuir-Blodgett trough. Depending on the chain length, and amount of dissolved salt in the droplets, the molecules will pack more tightly or are structured further apart. This may greatly influence the freezing point of an aerosol. Freezing experiments are conducted on aqueous NaCl droplets coated with the different organics at ESP. The freezing experiments are carried out using a cryo-cooling stage coupled to an optical microscope. The isotherms and ESP values provide a detailed molecular understanding of the effect of surface active organic compounds on the freezing of aqueous salt particles.

This work was supported by the NOAA Climate Program Office, Atmospheric Composition & Climate Program, Grant NA08OAR4310545.

 

Adam Greeley and Kamazima Lwiza, School of Marine & Atmospheric Sciences — Seasonal and inter-annual variations of ocean chlorophyll-α production and implications on global climate change.

The concentrations of chlorophyll-α in the world’s oceans have a profound impact on the global carbon cycle, particularly with regard to the consumption of carbon dioxide. Surface chlorophyll-α concentrations are dependent on a variety of factors including sea surface temperature (SST), cloud cover, photosynthetically active radiation (PAR), available nutrients, and surface wind speeds. In order to produce better estimates of global warming, there is a need to examine the ocean’s role as a sink of global atmospheric carbon dioxide and the feedback mechanisms involved in climate change. The first step is to understand the mechanisms that control the inter-annual and climatic variability of surface chlorophyll-a concentrations. Here we use satellite data from the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) and Advanced Very High Resolution Radiometer (AVHRR) to examine that the impact of different combinations of SST, PAR (which intrinsically includes cloud cover), and surface wind speeds on surface chlorophyll- α concentrations.

Kate A. Lavelle, John M. Carroll, Bradley J. Peterson, School of Marine & Atmospheric Sciences — Can Codium fragile provide juvenile bay scallops an above-bottom refuge from benthic predation?

Eelgrass (Zostera marina) is recognized as being the preferred habitat of bay scallops (Argopecten irradians), providing an above-ground spatial refuge for juveniles until they reach a size predation threshold. However, eutrophication, harmful algal blooms, and habitat loss have significantly reduced eelgrass abundance along the historic range of bay scallops. In Long Island estuaries, populations of bay scallops have declined dramatically in correlation with the loss of eelgrass meadows. An introduced and locally abundant macroalgae (Codium fragile) may serve the same role as a predation refuge since juvenile scallops have been observed attached to the C. fragile canopy in the field. The purpose of this study was to quantify the role of C. fragile as an above-bottom refuge for juvenile bay scallops from crab predation. In a laboratory experiment, juvenile scallops (mean shell height 12.6 mm) were tethered to both eelgrass and C. fragile canopies. Mud crabs (Dyspanopeus sayi) were allowed to forage for the scallops for 24 hours. Scallop survival in eelgrass and C. fragile showed no significant difference. Survival statistics indicate that C. fragile may provide a comparable predation refuge from benthic crabs for juvenile scallops as Z. marina. This project was supported by URECA and the Evan Frankel Foundation.

Melissa Mazzocco, Joseph D. Warren, School of Marine and Atmospheric Sciences, Stony Brook University and Robert DiGiovanni, Riverhead Foundation for Marine Research & Preservation, Riverhead, NY — Analysis of vocalizations from a captive bottlenose dolphin (Tursiops truncatus)

A mother and calf bottlenose dolphins (Tursiops truncatus) were rescued by the Riverhead Foundation in late September 2006 from Sag Harbor, NY. Unfortunately the mother did not survive transport to the Riverhead Foundation’s rehabilitation facility. The calf, named Ariel, did survive and was placed in a large tank for rehabilitation. After arrival at Riverhead, Ariel was kept alone in the tank with periodic medical examinations and interaction sessions with Riverhead staff. Roughly one month later an underwater microphone (hydrophone) was placed within her enclosure and recordings were made periodically throughout the day while members of the Riverhead staff were present. The recordings varied in length from 3 to 600 seconds. Initial recordings had a sampling rate of 22.5 kHz but this was later changed to 48.0 kHz. In addition to the recordings, the Riverhead Foundation staff recorded the occurrence of stimulus and other interactions that occurred in the tank. We examined several hundred recordings to measure the characteristics of Ariel’s vocalizations which were primarily made up of long series of whistles. Using Raven Lite 1.0 software (Cornell Lab of Ornithology), we measured several different vocalization parameters including: the beginning frequency, end frequency, peak frequency, maximum frequency, minimum frequency, and start time and duration of each complete whistle. We also noted other non-whistle vocalizations and non-dolphin sounds present within the recordings, the number of inflection points in each whistle, the presence of harmonics, and the time between whistles. We used this information to determine the whistle classification types, which was done using the identification numbers outlined in “Pitfalls in the categorization of behavior: a compilation of dolphin whistle classification methods.” (V. Janik, Animal Behavior, 57, 133-143). A total number of 4,833 whistles have been identified in the data set, but characterization of them is still ongoing. By far the most common whistle type identified thus far has been type 90. The frequency of whistles varied greatly amongst our data set and we are investigating whether external stimuli may be related to an increase in whistle occurrence.

Daryl McHugh, Joseph Ruggieri, Xiaolin Li, and Bruce Brownawell, School of Marine & Atmospheric Sciences — An assessment of quaternary ammonium compounds in biosolids

Biosolids are the solid portion of treated sewage sludge that may be recycled as compost for the beneficial use of their nutrient-rich organic materials. By far, the largest sector of beneficial reuse of biosolids is land application in agriculture. Other beneficial areas include commercial and domestic landscaping/gardening, forestry and mine reclamation. Alternative fates of biosolids are storage, landfilling and incineration, with incineration being most common. Biosolid composting is appealing because it appears to provide a beneficial recycling of sewage sludge, which had previously been incinerated, landfilled or dumped into open waters to a large extent. Such practices are seen as environmental risks. The past several years have witnessed an increase in biosolids production and reuse, both in the U.S. and abroad (especially Europe). A 1999 EPA report estimated that 6.9 million dry tons of biosolids were generated in 1998 in the U.S., with approximately 60% beneficially reused. By 2010, it is projected that 8.2 million dry tons of biosolids will be produced, with 70% beneficially reused. Now, there is increasing concern as to potential environmental and health risks associated with the application of biosolids in agriculture. There is much uncertainty about the presence and concentration of contaminants in biosolids, especially organic chemicals used in pharmaceuticals and personal care products.

This research is the first study to examine the fate and concentration of the class of organic contaminants known as quaternary ammonium compounds (QACs). QACs are an important class of cationic surfactants used in fabric softeners, personal care products and antimicrobials. QACs strongly sorb to solid matrices, providing a possible reason why they are persistent in biosolids. An initial assessment of the distribution of 19 QACs in samples indicates total QAC concentrations varying between 190 and 760 μg/g. Approximately half of the total QAC concentrations may be attributed to C16:16, C16:18 and C18:18 dialkyldimethylammonium compounds, which are used in fabric softeners. A critical discovery is the exceptionally high levels of C22 alkyltrimethylammonium, a previously unreported persistent environmental contaminant. Biosolid samples collected in 2003 had C22 alkyltrimethylammonium concentrations varying between 22 and 53 μg/g, while 2009 samples had concentrations as high as 290 μg/g. This compound is an ingredient in many hair care products, whose use has increased exponentially in recent decades. The high levels of QACs (especially the previously unmeasured C22 alkyltrimethylammonium) makes the study of biosolids of the utmost importance. In addition to these QAC compounds, the levels of QACs will be compared to those previously recorded contaminants found in biosolids and offer an evaluation of present regulatory laws and policies concerning the use of biosolids.

We are grateful for the support of the NIEHS Superfund Basic Research Program that sponsored this study under grant ES07384.

Kristen D. Onsgard, Kestrel O. Perez, and Stephan B. Munch, School of Marine & Atmospheric Sciences — Effect of density on growth in a common marine fish

Many studies have shown that density impacts growth and population dynamics including predation, competition, and reproduction. In fish species that are valuable commercially, density also has an effect on growth and survival. We investigated the effect of stocking density on growth in Atlantic silversides, Menidia menidia, a common estuarine fish. We stocked fish of the same initial mean size at three different densities (low (n=20), medium (n=50), and high (n=70), and measured all individuals on a bi-weekly basis for 1 month. After two weeks, the effect of density on growth was clear: individuals stocked at the highest density had significantly slower growth (regression p=0.0007, n=6). The effect of density after 1 month was not as apparent, as growth in all treatments slowed (regression p=0.3, n=6). These results indicate that density effects on growth are most important early in life. This research was conducted at the Flax Pond Marine Lab and supported, in part, by grants from NY DEC and the National Science Foundation.

Brandilyn Peters and Anne McElroy, School of Marine & Atmospheric Sciences — Sex ratios as evidence of endocrine disruption in winter flounder, Pseudopleuronectes americanus: Long Island and Hudson River studies

The purpose of our study was to evaluate the extent of endocrine disruption in winter flounder (Pseudopleuronectes americanus) by determining their sex ratios in the waters surrounding Long Island and the Lower Hudson River, New York. Previous research in our lab has shown that young -of-the-year (YOY) winter flounder from the polluted Jamaica Bay have higher ratios of females to males, and elevated levels of vitellogenin, a protein associated with female reproduction, as compared to a reference population from Shinnecock Bay at the eastern end of Long Island. In the summer of 2007, YOY winter flounder were collected from 9 sites on Long Island. I helped develop a method to determine sex in these very young fish in fresh frozen and histologically preserved samples. In apparent contrast to date from previous years, sex ratios from fish collected in the 2007 study showed more males than females in western Long Island embayments, though sample sizes were too small for this to be statistically significant. The correlation between longitude, with higher longitudes close to New York City as proxy for urbanization, and female sex ratio was also not significant. In contrast, sex ratios of YOY flounder collected from 24 locations in the lower Hudson River showed uniformly more females than males in all the Hudson River, though these differences were not large and also not statistically significant. Further work needs to be done to determine whether or not these apparent differences are significant. This work was supported with funding from Undergraduate Research & Creative Activities.

Andrea Tomasso and Joseph D. Warren, School of Marine & Atmospheric Sciences — Detecting the presence of Upper Circumpolar Deep Water near Livingston Island, Antarctica

A series of research cruises was conducted from 2004 through 2007 in the waters just north of Cape Shirreff, Livingston Island, Antarctica as part of an investigation into krill abundance in these nearshore waters. Cape Shirreff is home to several Antarctic fur seal rookeries and penguin colonies. Both of these animals rely on Antarctic krill as a primary food source for themselves and their offspring. This study sought to determine if circumpolar deep water (CDW) was intruding via deep submarine canyons into the nearshore area of Cape Shirreff. In other Antarctic areas, the upwelling of CDW has been linked to increased productivity. The nearshore area of Cape Shirreff was surveyed by three roughly-parallel transects which were conducted at least once each year during January or February. Transects included the western submarine canyon (Y2 transect), the eastern submarine canyon (Y8 transect) and shelf area between the two canyons (Y5 transect). Hydrographic data were collected using a SeaBird CTD which recorded a variety of parameters (including temperature, conductivity, dissolved oxygen) in one meter depth intervals from the surface to the shallower of 750 m or the bottom. Conductivity, temperature, and depth data were used to calculate salinity and density. Klinck et al 2004 defined the characteristics of CDW as salinities ranging from 34.6-34.74 PSU and temperatures ranging from 1-2 ^oC. Knowing this information, contour plots were created for density, salinity, dissolved oxygen, and temperature by transect and used to detect the intrusion of CDW. TS plots showed the presence of CDW at the bottom of some of the stations farthest from shore. The CDW signature was not detectable at any of the other stations in the transects most likely due to mixing of the water column. Surveys conducted in 2005-2007 detected a stronger CDW signature in the Y2 transect (western canyon) than in the Y8 transect (eastern canyon). We also examined the variability of the hydrography for years where we had multiple passes of each transect. This research was supported by the National Science Foundation?s Office of Polar Programs and the National Oceanic and Atmospheric Administration’s Antarctic Marine Living Resources Program.