Papers by Christopher Hartleb
Aquaculture magazine., 2004
AFS 142nd Annual Meeting, Aug 21, 2012
Fisheries Research, Oct 1, 1995
... improved gastric lavage device for removing stomach contents from live fish Christopher F. Ha... more ... improved gastric lavage device for removing stomach contents from live fish Christopher F. Hartleb, John R. Moring * National Biological Survey, Maine Cooperative Fish and Wildlife Research Unit1, Department of Zoology, University of Maine, 5751 Murray Hull, Orono, Maine ...
Freshwater Biology, Oct 1, 1991
York is diverse, composing of forty-eight submersed species representing a wide range of habitats... more York is diverse, composing of forty-eight submersed species representing a wide range of habitats, depth ranges and life-history strategies. The photosynthetic rates of seven representative submersed aquatic macrophytes were determined in laboratory studies using measurements of short-term changes in oxygen concentration at eight light intensities from 0 to 1000 |.imol m~^ s'' at 20°C. The species examined were: Elodea canadensiSy Myriophyllum spicatum., Potamogeton amplifoUus, P. gram-inet4S, P. praelongus, P. robbinsii, and ValUsneria americana. 2. Comparisons of maximum net photosynthesis, Miehaelis-Menten V(nax and Km for photosynthesis versus irradiance, and dark respiration rates correlated with changes in community composition and species distribution with depth. 3. In particular, Myriophyllum spicatum exhibited a high photosynthetic rate (V^ax) and high hght requirement (both in compensation point and higher half-saturation constant {K^) indicative of a high lightadapted species. In contrast, the native species exhibited shade-^tolerant characteristics. 4. Simple daily carbon balance models indicate that M. spicatum has a higher positive carbon balance near the surface than the native species, but carbon balance decreased more rapidly with decreased light. All species showed greatly reduced carbon balances under a simulated M. spicatum canopy, indicating that native species might not survive. Myriopyllum spicatum leaves would experience self-shading and eventual sloughing.
Journal of Freshwater Ecology, Mar 1, 2000
Aquaculture Research, Feb 4, 2016
This study evaluated the effects of AQUI-S®20E (10% eugenol) sedation on the survival and behavio... more This study evaluated the effects of AQUI-S®20E (10% eugenol) sedation on the survival and behaviour of yellow perch Perca flavescens (Mitchill) and Nile tilapia Oreochromis niloticus L. held in high loading densities. Fish were held in 0–300 mg L−1 AQUI-S®20E (0–30 mg L−1 eugenol) for up to 10 h in static tanks. At 17°C, yellow perch held in 200 and 300 mg L−1 AQUI-S®20E were lightly sedated for up to 7 h. Yellow perch at 200 and 300 mg L−1 AQUI-S®20E also had >95% mean survival 7-days post exposure using loading densities up to 360 g L−1. Nile tilapia were only sedated for ≤3 h in concentrations up to 300 mg L−1 at 22°C and had >90% mean survival at loading densities ≤480 g L−1. Ammonia in tanks increased significantly as loading density increased, but treatment with AQUI–S®20E did not reduce ammonia accumulation. Results suggest that AQUI–S®20E was effective to sedate yellow perch and Nile tilapia at high loading densities, but sedation varied with loading density and species.
Aquaculture Research, May 28, 2014
Effects of eugenol (AQUI-S â 20E, 10% active eugenol) sedation on cool water, yellow perch Perca ... more Effects of eugenol (AQUI-S â 20E, 10% active eugenol) sedation on cool water, yellow perch Perca flavescens (Mitchill), and warm water, Nile tilapia Oreochromis niloticus L. fish metabolic rates were assessed. Both species were exposed to 0, 10, 20 and 30 mg L À1 eugenol using static respirometry. In 17°C water and loading densities of 60, 120 and 240 g L À1 , yellow perch controls (0 mg L À1 eugenol) had metabolic rates of 329.6-400.0 mg O 2 kg À1 h À1 , while yellow perch exposed to 20 and 30 mg L À1 eugenol had significantly reduced metabolic rates of 258.4-325.6 and 189.1-271.0 mg O 2 kg À1 h À1 respectively. Nile tilapia exposed to 30 mg L À1 eugenol had a significantly reduced metabolic rate (424.5 AE 42.3 mg O 2 kg À1 h À1) relative to the 0 mg L À1 eugenol control (546.6 AE 53.5 mg O 2 kg À1 h À1) at a loading density of 120 g L À1 in 22°C water. No significant differences in metabolic rates for Nile tilapia were found at 240 or 360 g L À1 loading densities when exposed to eugenol. Results suggest that eugenol sedation may benefit yellow perch welfare at high densities (e.g. live transport) due to a reduction in metabolic rates, while further research is needed to assess the benefits of eugenol sedation on Nile tilapia at high loading densities.
Aquaculture Research, Aug 25, 2022
Aquatic Botany, Mar 1, 1993
Myriophyllum spicatum L. is a submersed aquatic macrophyte that has colonized aquatic habitats ac... more Myriophyllum spicatum L. is a submersed aquatic macrophyte that has colonized aquatic habitats across North America. Vegetative propagation is prevalent in M. spicatum and is highly visible, because of the extraordinary capacity of this plant to spread by fragmentation. Because of this. sexual propagation has been considered of limited importance and little is known about in situ seed germination of this species. Laboratory studies were conducted on seeds of M. spicatum to determine the light and temperature requirements necessary for maximum seed germination. Seed germination was also examined in situ at depths of 1, 3 and 5 m in two bays at Lake George, New York (USA). Significant germination of seeds was observed in the northern bay of the lake, but not in the southern, probably because of increased sedimentation in the latter. Temperatures higher than 15 C were found to be necessary for successful seed germination in laboratory studies; however, light was determined not to be a limiting factor on its own. Seeds buried under more than 2 cm of sediment were shown to experience significant decreases in germinalion.
Journal of Industrial Ecology, Jan 7, 2022
Aquaponics, in which fish and plants are grown in a symbiotic closed‐loop industrial metabolism, ... more Aquaponics, in which fish and plants are grown in a symbiotic closed‐loop industrial metabolism, are promising test beds to implement industrial ecology in food production at a commercial scale. These systems have the potential to enhance the environmental and economic performance of aquaculture systems by reducing the overall burden on natural ecosystems (i.e., reducing resource and emission‐based impacts per unit of food produced). To holistically evaluate the environmental and economic implications of aquaponics, specifically in a cold‐weather climate, Life Cycle Assessment (LCA) and Economic Analysis (EA) were performed on a Midwestern United States aquaponic system, using data from 3 years of annual operation cycles with varying fish species production; tilapia, conventional walleye, and hybrid walleye. For the LCA, environmental impacts were quantified using 10 midpoint indicators. Assessments indicated that 1‐kg production of live‐weight tilapia, conventional walleye, and hybrid walleye resulted in 20.2‐13.8‐11.7 kg CO2‐eq, 23.0‐7.8‐3.9 g N‐eq, and 0.2‐0.3‐0.4 kg SO2‐eq, consecutively, using the investigated system. The most sensitive parameters for environmental impacts were heat, aquafeed, electricity, and infrastructure (in all scenarios). For EA, benefit to cost ratios (BCRs) and three other widely used indices were analyzed for production cycles. The BCRs were 0.47, 1.16, and 1.75 for tilapia, conventional walleye, and hybrid walleye, respectively (using a 10% discount rate and a 20‐year horizon), highlighting the necessity of optimizing both cash inflows (e.g., energy costs) and outflows (plant and fish revenues) to achieve practical enhancement of return on investments. The major cost contributors were infrastructure, labor, and heat (contributing to &gt;89% of total costs for all cycles). Suggested steps for in‐effect improvement of the investigated aquaponic system's environmental and economic favorability include heat and infrastructure optimization by (a) applying effective heating strategies (e.g., advanced insulation techniques), and (b) expanding the system's operational lifespan (e.g., prevention of waste accumulation).
Environmental Biology of Fishes
The effects of thermal stratification and light gradients on the feeding behavior of pumpkinseeds... more The effects of thermal stratification and light gradients on the feeding behavior of pumpkinseeds, Lepomis gibbosus, were tested in vertical aquarium columns. Successful captures, unsuccessful captures and unsuccessful searches by foraging sunfish on Daphnia pulex were recorded. Clearance and feeding rates of the sunfish were lowest when prey densities remained high, indicating that the Daphnia were occupying an area that could not be searched by the sunfish. Thermal stratification limited the searching volume and prey availability of the sunfish, while creating a refuge for the Daphnia. Light intensities ≤ 4.2 × 10-3 W m-2 decreased the searching and capture abilities of the sunfish under isothermal conditions. Thermal stratification had more of an effect than the light gradients, creating a refuge for the Daphnia causing them to be unavailable and less vulnerable to predation by the sunfish.
North American Journal of Aquaculture
The Cisco Coregonus artedi (also known as Lake Herring), a coldwater salmonid found in the Great ... more The Cisco Coregonus artedi (also known as Lake Herring), a coldwater salmonid found in the Great Lakes, is of interest to multiple agencies for restoration and conservation purposes due to its important ecological role. Further information on rearing and restocking of Cisco is needed, especially toward understanding the biological culture needs of Cisco eggs, larvae, and fingerlings. To address this gap in the literature and to provide essential fish culture information, we performed three preliminary studies in 2010 with Cisco: fertilization (wet versus dry fertilization), egg survival (pre‐water‐hardening versus post‐water‐hardening iodine treatment), and fry development (three different larval feed treatments that were commercially available at that time). The dry fertilization methodology (68%) yielded a significantly better eye‐up percentage than wet fertilization (34%). Additionally, our testing revealed higher survival rates when iodophor treatment was used on fertilized eggs...
Sea Grant is a unique partnership with public and private sectors combining research, education, ... more Sea Grant is a unique partnership with public and private sectors combining research, education, outreach and technology transfer for public service. It is a national network of universities meeting the changing environmental and economic needs of people in our coastal, ocean and Great Lakes regions.
Journal of Cleaner Production, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Aquacultural Engineering, 2009
Aquaculture, Fish and Fisheries
Uploads
Papers by Christopher Hartleb