Research & Findings
Nancy J. Leland, Sheri Caseau, Eleah Caseau, Jeffrey T. Miller, Alison Watts, James F. Haney, 2023
Picocyanobacteria are known to be a diverse and widely distributed group of cyanobacteria that occupy a wide range of ecological niches including freshwater, brackish and marine microhabitats. In general, cyanobacterial populations can be described using photosynthetic accessory pigments and size-structure analysis to provide detailed descriptions of these populations. Read More
Nancy J. Leland, Kimberley Crocker Pearson, Marty K. Burke, Jeffrey T. Miller, Alison Watts, James F. Haney, 2023
Cyanobacteria are known to be a diverse and widely distributed group of bacteria that occupy a wide range of ecological niches. Their populations can be described using cyanobacterial accessory pigments and size-structure analysis [1] where cell size and organization are important parameters. The cyanobacteria produce secondary metabolites that have been shown to be toxic to various receptors, commonly termed cyanotoxins, making them a threat to human and ecological health. Read More
Nancy J. Leland, 2022
Lim-Tex was contracted by the Town of Concord in 2022 to monitor the cyanobacterial populations in White Pond following the CyanoCastingTM Program. The program relies upon the collection of size-fractionated samples1,2 following the EPA approved QAPP3, representing unique cyanobacterial populations to provide data documenting increased biomass leading to water quality issues including cyanobacterial accumulations in the water column (a.k.a. transparency) and at the surface (a.k.a. blooms), estimation of microcystin concentrations and evaluation of trophic interactions. Read More
Nancy J. Leland , James F. Haney, Amanda M. McQuaid, Sheri Caseau, 2022
A comprehensive cyanobacteria monitoring program following the Quality Assurance Program Plan (CMC-QAPP) for the Cyanobacteria Monitoring Collaborative Program (EPA, 2017) was implemented in 2021 in collaboration with the Martha’s Vineyard Commission (MVC), the Martha’s Vineyard Shellfish Group (MVSG) and the Wampanoag Tribe of Gay Head (Tribe) to provide an island-wide assessment of cyanobacterial populations. Read More
Nancy J. Leland, 2022
Aquatic ecosystems, including lakes, harbor community food webs, supported by the complex interactions between a myriad of biotic and abiotic factors. In temperate zones, freshwater lakes can display seasonal patterns indicative of changes in nutrient supply, community composition, relative abundance, and survivorship giving rise to diverse populations within a trophic spectrum. The trophic spectrum concept recognizes traditional vertical models using nutrients (“bottom-up”) and predator-prey relationships (“top-down), horizontal influences (trophic compensation, keystone species) and subtle resource-driven opportunistic behaviors that sculpt populations. Read More
Nancy J. Leland, 2020
In 2019, a study to determine the influence of biotic variables on the aerosolization of cyanotoxins was conducted in Lower Mill Pond which is at the terminus of the Mill Ponds Complex in Brewster, MA exiting via Stony Brook to the nearby estuary. Stony Brook is the largest herring run in the Cape Cod North region, and supports one of the largest freshwater spawning sites of Alosa pseudoharengus. The early larval and juvenile forms of Alosa are known to be planktivorous, where heavy feeding upon their preferred food source of large crustacean zooplankton often results in changes to their composition and size structure. A change in the zooplankton can influence the composition and size structure of the cyanobacterial population. Read More
Nancy J. Leland , James F. Haney, Ryan A. Landon, 2020
Alosa pseudoharengus is an anadromous fish that migrates from marine to freshwaters to spawn. The early larval and juvenile forms are known to be planktivorous, where heavy feeding upon their preferred food source of large crustacean zooplankton often results in changes to composition and size structure within this trophic guild which in turn can result in shifts within the trophic spectrum and a classic trophic cascade. Read More
Nancy J. Leland , James F. Haney, Kristin Conte, Karen Malkus-Benjamin, Bryan Horsely , 2019
Cyanobacterial populations in surface waters, including drinking water supplies and recreational waters, represent an ever present challenge for resource managers. As communities continuously respond to external and internal processes, dynamic profiles of composition, dominance, growth and toxigenicity emerge. In this study measures of size structure and biomass, quantified using light microscopy and fluorometry, were used to estimate microcystin concentrations through linear regression analysis. Read More
Nancy J. Leland, James F. Haney, 2019
The management of cyanobacteria and potential exposure to associated bio-toxins requires the allocation of scarce resources across a range of freshwater resources within various jurisdictions. Cost effective and reliable methods for sample processing and analysis form the foundation of the protocol yielding reliable data from which to derive important decisions. In this study the utilization of new methods to collect, process and analyze samples enhanced our ability to evaluate cyanobacterial populations. Read More