Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 55-59). Also available on the World Wide Web.

Thesis (M.S.) in Ecology and Environmental Science--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 73-78).

Thesis (M.S.) -- Central Connecticut State University, 2009. / Title from electronic title page. Project advisor: John Harmon. "A special project submitted in partial fulfillment of the requirements for the degree of Master of Science in Geography." Includes bibliographical references. Also available via the World Wide Web.

Vernal pools are often defined as seasonal pools that typically are inundated beginning in the winter and then drying out completely in summer. Though evidence of spatial and temporal variability in the macroinvertebrate communities of vernal pools has been found in previous studies, it has not been studied extensively. The primary objective of this study was to determine the extent of variability in the macroinvertebrate communities within vernal pools closely situated in a forested landscape. An effort was made to explain this variability with respect to certain physiochemical environmental variables of the pools. Significant variability was observed in the macroinvertebrate communities within the vernal pools both spatially and temporally. Water temperature, as an indicator of seasonal changes, was strongly correlated with the observed variations. Higher species richness and diversity were observed in the pools in winter than in spring 2007. Chironomidae was the most diverse family (8 genera) occurring in these vernal pools. At the beginning of inundation, amphipods and copepods were more abundant. β-diversity was low in both winter and spring 2007; α-diversity in winter was high and low in spring 2007.

No description available.

Aquatic habitats are closely linked to surrounding terrestrial environments via reciprocal subsidies. Much of the research on these subsidies has been focused on streams, while subsidies across aquatic-terrestrial boundaries of other aquatic systems, like temporary ponds, have received little attention. Temporary ponds are seasonally inundated aquatic habitats and patterns of energy transport across transient aquatic-terrestrial boundaries are not well understood. To address the lack of information regarding these cross-habitat subsidies, I quantified: 1) leaf litter inputs, 2) amphibian egg inputs, 3) terrestrial insect inputs, 4) amphibian metamorph emergence, and 5) aquatic insect emergence for eight temporary ponds. Terrestrial insect inputs to ponds represented substantial high-quality subsidies to ponds that are generally unaccounted for in similar studies. While larger ponds produced greater total fluxes to terrestrial habitats, smaller ponds were often more productive per unit area. Therefore, a mosaic of small ponds may produce greater or equivalent subsidies and may be of greater value to terrestrial food webs than a single large pond. Resource subsidies of energy and nutrients can be transported via physical forces or biotic processes, such as animal migration or emigration. I quantified net nutrient fluxes associated with amphibian migrations across aquatic-terrestrial boundaries of eight temporary ponds in Illinois. I measured carbon (C), nitrogen (N), and phosphorus (P) subsidies from forests to ponds, in the form of eggs, and the reciprocal subsidies from ponds to forests via juvenile emigration. Juvenile emergence biomass did not resemble egg biomass, as not all species bred successfully in each pond, resulting in variability in the magnitude of nutrient fluxes both across ponds and species. The forest was not always the recipient system of net nutrient fluxes. Hydroperiod, trophic interactions, and species composition explained some dynamics of N and P subsidies. Most studies have focused on the magnitude of cross-boundary fluxes, but the impact of a subsidy is mediated by the size of the flux as well as the quality and relative abundance of similar resources in the recipient habitat. Long-chain polyunsaturated fatty acids (LC-PUFAs) are necessary for proper physiological function, are unevenly distributed across the landscape, and animals differ greatly in their ability to synthesize them de novo. This creates the potential for limitation and increases their possible importance as a subsidy. I examined LC-PUFA tissue concentration and export in eight species of emerging amphibian metamorphs across eight temporary ponds in a wetland complex. I found that tissue concentrations and export of LC-PUFAs varied across species, but were generally within the ranges of several freshwater fish and aquatic insects. Anurans exported higher amounts of LC-PUFAs than salamanders, largely due to the higher emergence biomass of anurans. Further, I explored fatty acid profiles and immune function of wolf spiders in wetland and upland habitats. Wetland spiders had higher tissue levels of aquatic-derived LC-PUFAs and elevated immune function compared to upland spiders. These patterns suggest aquatically derived nutrients, such as LC-PUFAs, may benefit organisms exploiting freshwater habitats.

Much of the world’s aquatic food webs and nutritional relationships have been blurred by the ever-increasing evidence that many phytoplankton are not exclusively heterotrophic or autotrophic, but instead mixotrophic. Mixotrophy is a continuum of different energy and carbon-acquisition mechanisms utilizing both autotrophy and heterotrophy which distorts the concept of single trophic tier modality. This makes mixotrophs flexible to adapt to environmental pressures and is becoming more the rule than the exception in many aquatic ecosystems. One unique environmental setting where mixotrophy could be highly beneficial to food web stability is in seasonally occurring ephemeral pools – aka vernal pools. Mid-Atlantic vernal pools are biodiverse biogeochemical hotspots and critical breeding habitats for a diverse number of endemic taxa including many endangered amphibian species. Vernal pools are not permanent standing bodies of water and have fluxes in hydrology, temperatures, nutrients, and irradiance to name a few. These extremes make vernal pools an ideal setting for mixotrophic phytoplankton, however it’s never been investigated. Our survey found mixotrophy in every vernal pool sampled, as well as elevated grazing rates in pools experiencing nontypical seasonal conditions. From these small-scale forest pools to the world’s oceans mixotrophy is a widespread nutritional strategy. The Southern Ocean is essential for powering worldwide ocean circulation, regional biogeochemical cycles, and global climate. One of the major hurdles with understanding mixotrophy is identifying the phytoplankton capable of shifting nutritional strategies. While many Southern Ocean plankters have been properly identified as mixotrophic, one such keystone species has gone mislabeled until now. Phaeocystis antarctica is a well-studied Haptophyte algae that plays major roles in the global carbon and sulfur cycles. This species has been historically labeled as an obligate phototroph, but contradictory survives the long dark Antarctic winter without any known evidence of encystment. We suspect that this highly abundant species is in fact mixotrophic, capable of phagocytosis to supplement the irradiance shortcomings of the Antarctic dark. We experimented with varying degrees of light and nutrient limitations to determine possible triggers for P. antarctica grazing. Our results showed P. antarctica ingesting in every treatment, but its highest grazing rates corresponded with limitations to its primary photosynthetic mode. Apart from the newly realized complexity P. antarctica brings to the Southern Ocean food web, it is an environment that suffers from microplastic pollution that can impede these mixotrophic species. Mismanaged plastic waste around the world, especially microfiber discharge from laundered synthetic textiles, escape into the natural environment, and eventually concentrate in the oceans. The Southern Ocean can become disproportionately polluted in regions due to microfibers becoming sequestered once crossing the Antarctic circumpolar current and even becoming trapped in sea-ice formations. While it is easy to see the devastation plastic waste has on megafauna (i.e. turtles, fish, birds, and whales), its microscopic devastation is less obvious. Plastic waste comes in many forms and one less researched form is buoyant polyester microfibers <1mm that interact with colony forming algae. We utilized different concentrations of polyester microfibers and mixing speeds to determine if microfiber interactions with colony formations increases or decreases overall colony buoyancy. Smaller concentrations of polyester microfibers can impart a positively buoyant effect onto P. antarctica colonies regardless of mixing speed, however larger concentrations negatively affected colony buoyancy regardless of mixing speed. / Biology

Temporary snowmelt pool ecosystems in southwestern Quebec were examined with special emphasis on identifying the macrofauna and determining their spatial distribution, as well as ascertaining temporal changes in community composition. 68 taxa were collected from ten snowmelt pools. Major taxa represented were Diptera, Coleoptera, Hemiptera, Trichoptera, Odonata, Ephemeroptera, Anostraca, Isopoda, Amphipoda, Gastropoda and Bivalvia; the insects dominated the communities and the Culicidae (Diptera) was the most abundant taxon collected. The fauna were unevenly distributed both spatially and temporally amongst the pools. The occurrence of taxa was similar in pools in the same geographic location. The habitat characteristics of each pool, coupled with their proximity to a permanent waterbody and their accessibility to organisms, perhaps influenced the distribution of the various taxa. A successional pattern was observed in which filter-feeders and detritivores appeared first, followed by predators. After drought, a similar pattern was seen in pools that were replenished by summer rains, but taxon diversity was lower. In addition, pools with longer hydroperiods harboured more taxa than shorter-lived pools.

Vernal pools are temporary aquatic habitats that can be home to dozens of 4 invertebrate species. Unfortunately, over 90 percent of California vernal pool habitat has been destroyed. To better understand the remaining habitat, this study focused on the species community structure of the pools, determined similarity among sites, and the pool characteristics important to survival of these organisms. Vernal pools at four distinct sites in the Sacramento Valley during winter 2012 were sampled for crustaceans and water characteristics every 2 weeks for 14 weeks. Twenty-two species of crustaceans were identified, 13 of which are possibly new species. In this dry, late rainfall year, fairy shrimp and copepods were the first species to emerge in large numbers. Ostracods, Cladocera and clam shrimp experienced large populations later in the season. Temperature showed strong correlations with most species and likely affected growth rates and emergence; conductivity, depth, and surface area were also positively correlated with several species abundance. Understanding the emergence and distribution of these crustaceans is necessary to protection of remaining habitat.

No description available.