Holly Plaisted - Academia.edu (original) (raw)

Papers by Holly Plaisted

Marine Pollution Bulletin

Lake and reservoir management, Dec 11, 2017

The landscape of Cape Cod (Massachusetts, USA) is scattered with numerous freshwater lakes (known... more The landscape of Cape Cod (Massachusetts, USA) is scattered with numerous freshwater lakes (known as kettle ponds) that offer abundant recreational opportunities and provide important habitat for a wide variety of flora and fauna. The rapid urbanization of Cape Cod has been cause for concern regarding potential impacts on these waterbodies. Septic system delivery of nutrients to the ponds and atmospheric nitrogen deposition from fossil fuel combustion has been high for many decades in this region. These systems have also undergone significant shifts in pH and temperature due to regional changes in air quality and climate warming. All factors have the potential to alter pond trophic state and, consequently, water clarity. In this study, we examined August trends in kettle pond Secchi depths within Cape Cod National Seashore from 1996 to 2016. We further analyzed relationships by regression analysis between recent (2013-2014) measurements of Secchi depths and water quality constituents, physical features, shoreline housing densities, and the occurrence of gulls, fish stocking, and herring spawning. This provided a "snapshot" portrait of the current state of these ponds and their functioning. The results suggest that water clarity has remained unchanged or has even increased over the last 2 decades. Water clarity was negatively related to deep-water nutrient concentrations (total nitrogen and phosphorus), which themselves were negatively correlated with pond depth. The occurrence of gulls and anadromous and stocked fish populations had no apparent effect on water clarity, nor did any of the variables that described housing densities around ponds.

Frontiers in Marine Science

Sea surface temperature (SST) has increased worldwide since the beginning of the 20th century, a ... more Sea surface temperature (SST) has increased worldwide since the beginning of the 20th century, a trend which is expected to continue. Changes in SST can have significant impacts on marine biota, including population-level shifts and alterations in community structure and diversity, and changes in the timing of ecosystem events. Seagrasses are a group of foundation species that grow in shallow coastal and estuarine systems, where they provide many ecosystem services. Eelgrass, Zostera marina L., is the dominant seagrass species in the Northeast United States of America (USA). Multiple factors have been cited for losses in this region, including light reduction, eutrophication, and physical disturbance. Warming has the potential to exacerbate seagrass loss. Here, we investigate regional changes in eelgrass presence and abundance in relation to local water temperature using monitoring data from eight sites in the Northeastern USA (New Hampshire to Maryland) where a consistent monitorin...

This dataset consists of one data file (Carman_Et_al_Tunicate_2017_survey_on_eelgrass_quad_data_f... more This dataset consists of one data file (Carman_Et_al_Tunicate_2017_survey_on_eelgrass_quad_data_final) and one definitions file (Carman_Et_al_Tunicate_2017_survey_on_eelgrass_quad_data_final_definitions). The data file consists of species and abundance of tunicates found growing on eelgrass (Zostera marina L.) in a survey of 33 northwest Atlantic eelgrass meadows in summer 2017. Eelgrass meadows represented in the dataset range from New Jersey to Newfoundland. Within each meadow, data were collected within individual quadrats (ranging from 0.0625 to 0.25 square meter) along transects or as general site surveys. Data include geographic coordinates for the center of each site surveyed; date surveyed; tunicate species found on eelgrass; percent cover of tunicates on eelgrass leaves; eelgrass density; eelgrass canopy height; and the name of the investigator who collected each data point.

Inland Waters, 2018

Abstract Freshwater lakes throughout many parts of the world have undergone substantial warming i... more Abstract Freshwater lakes throughout many parts of the world have undergone substantial warming in response to climate change. In southern New England, within Cape Cod National Seashore (CCNS; Massachusetts, USA), numerous freshwater lakes known as “kettle ponds” scattered throughout the landscape have exhibited increasing surface water temperatures for the past 2 decades. In this study, we examined changes in summer air temperatures, wind speeds, underwater light transmission (3 of the primary factors influencing lake thermal structure), and the temperature profiles of 9 ponds from 1996 to 2014. Mean, minimum, and maximum daily air temperatures all increased significantly while mean daily maximum and average wind speeds declined. The attenuation of light to 50% and 25% of surface intensities occurred at significantly greater depths in 7 ponds, whereas the depths at which light transmission was 1% of surface values increased in 3 ponds. Thermocline depths became shallower in 2 ponds while temperature between surface and bottom waters increased in 6 ponds. Bottom waters exhibited significant cooling in 4 ponds while Schmidt stability values (which indicate the strength of thermal stratification) increased in 5 ponds. Thermocline depth among ponds was positively correlated with light transmission variables for the majority of years between 1996 and 2014, and all temperature variables were significantly correlated with mean daily air temperature. The patterns indicate a general strengthening of thermal stability during the summer and seem to be related to increasing local air temperatures and reduced wind speeds. Implications of changes in the thermal properties of CCNS ponds are discussed in the context of potential physical, chemical, and ecological processes.

Estuaries and Coasts, 2020

In the original version of the article, there was an error in the column headings on the second p... more In the original version of the article, there was an error in the column headings on the second page of Table 7. Low OM × 100% light and Low OM × 58% light should be High OM × 100% light and High OM × 58%, respectively. The original article has been corrected.

Estuaries and Coasts, 2019

Eelgrass (Zostera marina L.), an underwater marine flowering plant, has a high degree of morpholo... more Eelgrass (Zostera marina L.), an underwater marine flowering plant, has a high degree of morphological plasticity that allows it to survive and adapt to environmental changes. To test the effect of eelgrass genetic diversity (measured as allelic richness and observed heterozygosity) on resilience to stresses associated with eutrophication, eelgrass from ten genetically differentiated populations was studied in outdoor mesocosms. In a full factorial experiment lasting 3 months, eelgrass was subjected to two light levels (100 and 58% ambient) and two sediment treatments (1 and 8% organic content). Some populations of eelgrass showed higher resilience, measured as a combination of productivity and survival, when exposed to the stress of high sediment organic matter and, to a lesser extent, reduced light. Overall, eelgrass resilience correlated positively with eelgrass source population genetic diversity. The findings show that eelgrass resilience to stress typical of eutrophic estuaries (low light, high organic sediment) is improved by genetic diversity, with implications for transplantation, conservation, and management.

Lake and Reservoir Management, 2017

PeerJ, 2017

Global declines in coastal foundation species highlight the importance of effective restoration. ... more Global declines in coastal foundation species highlight the importance of effective restoration. In this study, we examined the effects of source population identity and diversity (one vs. three sources per plot) on seagrass (Zostera marina) transplant success. The field experiment was replicated at two locations in Massachusetts with adjacent natural Zostera marina beds to test for local adaptation and source diversity effects on shoot density. We also collected morphological and genetic data to characterize variation within and among source populations, and evaluate whether they were related to performance. Transplants grew and expanded until six months post-transplantation, but then steadily declined at both sites. Prior to declines, we observed variation in performance among source populations at one site that was related to morphological traits: the populations with the longest leaves had the highest shoot densities, whereas the population with the shortest leaves performed the...

Colonization of eelgrass (Zostera marina L.) by tunicates can lead to reduced plant growth and su... more Colonization of eelgrass (Zostera marina L.) by tunicates can lead to reduced plant growth and survival. Several of the tunicate species that are found on eelgrass in the northwest Atlantic are highly aggressive colonizers, and range expansions are predicted in association with climate-change induced increases in seawater temperature. In 2017, we surveyed tunicates within eelgrass meadows at 33 sites from New Jersey to Newfoundland. Eight tunicate species were identified colonizing eelgrass, of which four were non-native and one was cryptogenic. The most common species (Botrylloides violaceus and Botryllus schlosseri) occurred from New York to Atlantic Canada. Tunicate faunas attached to eelgrass were less diverse north of Cape Cod, Massachusetts. Artificial substrates in the vicinity of the eelgrass meadows generally supported more tunicate species than did the eelgrass, but fewer species co-occurred in northern sites than southern sites. The latitudinal gradient in tunicate divers...