Zweifel R.D.,Inland Fisheries Research Unit |
Landis A.M.G.,Ohio State University |
Landis A.M.G.,Auburn University |
Hale R.S.,045 Morse Road |
Stein R.A.,Ohio State University
Transactions of the American Fisheries Society | Year: 2010
We parameterized and evaluated a bioenergetics model for saugeye (walleye Sander vitreus × sauger S. canadensis) by using laboratory experiments in an effort to improve predictions of prey consumption. First, we measured daily prey consumption rate and growth of age-0 and age-1 saugeyes fed two daily rations (ad libitum and 50% of maximum) at five temperatures ranging from 10°C to 28°C. Additional experiments quantified routine respiration rates and waste losses for three ages of saugeye (ages 0, 1, and 2) at five temperatures ranging from 10°C to 28°C. Mean daily rates of prey consumption (g · g -1 · d -1) by saugeyes increased from 10°C to 25°C, declining at 28°C. Respiration rates (g O 2 · g -1 · d -1) increased over the entire range of water temperatures. Waste losses were minor for saugeyes as egestion averaged 3.5% of consumed energy and energy lost via excretion was 4.5% of assimilated energy. We evaluated the accuracy of bioenergetics model predictions of saugeye prey consumption using daily prey consumption and corresponding growth data from our first set of experiments. Model estimates of prey consumption rates (g · g -1 · d -1) closely followed observed trends, providing reasonable estimates of cumulative prey consumption across temperature and fish size. The saugeye model provided improved estimates of consumption compared with a model published for walleyes (Kitchell et al. 1977), especially when water temperatures were in excess of 25°C. The differences we observed in predictive performance between the two models resulted from higher thermal optima for saugeyes compared with walleyes, and waste constants for saugeyes were two to three times lower than those calculated from the walleye model. These differences may largely be responsible for the walleye model's overestimation of consumption. Saugeye thermal optima are warmer than those of either parent species, and saugeye is better suited for warm, productive midwestern U.S. reservoirs. The saugeye model developed herein will improve the ability of managers to more accurately predict the consumptive demand of in situ saugeye populations and better tailor stocking rates to match available prey biomass. © American Fisheries Society 2010.
Sindt A.R.,Iowa State University |
Sindt A.R.,Inland Fisheries Research Unit |
Pierce C.L.,U.S. Geological Survey |
Quist M.C.,U.S. Geological Survey
North American Journal of Fisheries Management | Year: 2012
Effective conservation of fish species of greatest conservation need (SGCN) requires an understanding of species– habitat relationships and distributional trends. Thus, modeling the distribution of fish species across large spatial scales may be a valuable tool for conservation planning. Our goals were to evaluate the status of 10 fish SGCN in wadeable Iowa streams and to test the effectiveness of IowaAquatic Gap Analysis Project (IAGAP) species distribution models. We sampled fish assemblages from 86 wadeable stream segments in the Mississippi River drainage of Iowa during 2009 and 2010 to provide contemporary, independent fish species presence–absence data. The frequencies of occurrence in stream segments where species were historically documented varied from 0.0% for redfin shiner Lythrurus umbratilis to 100.0% for American brook lamprey Lampetra appendix, with a mean of 53.0%, suggesting that the status of Iowa fish SGCN is highly variable. Cohen’s kappa values and other model performance measures were calculated by comparing field-collected presence–absence data with IAGAP model–predicted presences and absences for 12 fish SGCN. Kappa values varied from 0.00 to 0.50, with a mean of 0.15. The models only predicted the occurrences of banded darter Etheostoma zonale, southern redbelly dace Phoxinus erythrogaster, and longnose dace Rhinichthys cataractae more accurately than would be expected by chance. Overall, the accuracy of the twelve models was low, with a mean correct classification rate of 58.3%. Poor model performance probably reflects the difficulties associated with modeling the distribution of rare species and the inability of the large-scale habitat variables used in IAGAP models to explain the variation in fish species occurrences. Our results highlight the importance of quantifying the confidence in species distribution model predictions with an independent data set and the need for long-term monitoring to better understand the distributional trends and habitat associations of fish SGCN. © American Fisheries Society 2012.
Sovic M.G.,Ohio State University |
Denlinger J.C.,Inland Fisheries Research Unit |
Fuerst P.A.,Ohio State University
North American Journal of Fisheries Management | Year: 2012
Hybridization and introgression continue to gain recognition as important issues in the management and conservation of native fishes. It is often necessary to identify hybrids in natural populations and to distinguish among individuals of various hybrid categories. Molecular methods are important for these purposes, and it is valuable if researchers have a range of molecular methods to apply, since each method has unique advantages and disadvantages. The determination of the best class of marker for a particular study depends on various factors, including the goals of the study, the resolution required, and the genomic and marker information already available for the taxa of interest. We modified a protocol to generate fluorescent randomly amplified polymorphic DNA (FRAPD) markers for hybridization studies. To our knowledge, this type of marker has not previously been used for hybrid identification. To demonstrate the utility of the modified methods, FRAPD markers were used to evaluate potential reproduction by saugeye (female walleye Sander vitreus × male sauger Sander canadensis) in a central Ohio reservoir. Our approach successfully generated a battery of diagnostic genetic markers that were used to test the hypothesis that young-of-year saugeye were later-generation offspring of saugeye cohorts previously stocked into the reservoir. Alternatively, the fish may have been immigrant first-generation saugeye from other sources. Data obtained from the FRAPD markers provided strong support favoring the alternative hypothesis. These methods provide a very useful tool for distinguishing between pure parentals and various classes of hybrid individuals, both in Sander spp. and in other taxa, offering a powerful and easily developed alternative to othermolecularmethods of generating informative genetic markers for hybridization studies. © American Fisheries Society 2012.
Roy E.D.,Louisiana State University |
Martin J.F.,Ohio State University |
Irwin E.G.,Ohio State University |
Conroy J.D.,Inland Fisheries Research Unit |
Culver D.A.,Ohio State University
Ecological Engineering | Year: 2011
The objective of ecological engineering is to design sustainable ecosystems that integrate human communities and their natural environment for the benefit of both. In this paper, we illustrate how social-ecological modeling can be used as a tool to clarify this objective at a landscape scale for freshwater systems. Coupled social-ecological systems (SESs) are open, dynamic systems subject to both ecological and socioeconomic perturbations. Here we demonstrate the interactive effects of social and technological uncertainties on SES dynamics over time. Additionally, we integrate research on ecosystem stability, social-ecological modeling, and ecological engineering to offer guidance for research at the human-environment interface. Based on a case study of Lake Erie's Sandusky watershed, we use an integrated human-biophysical model to investigate the influence of two parameters on SES dynamics: (1) regional societal preferences that impact watershed management and (2) technological innovation that alters agricultural nutrient efficiency. Our results illustrate ways in which SES dynamics and optimum management strategies depend on societal preferences within the region, indicating a key area of uncertainty for future investigation. As guidance for SES restoration, our model results also illustrate the conditions under which technological change that increases nutrient efficiency on farms can and cannot create a win-win, or increase both human welfare and SES resistance to eutrophication simultaneously. Using these results, we elucidate the value of ecological engineering and offer guidance for assessments of ecological engineering projects using social-ecological modeling. © 2011 Elsevier B.V.
Bridgeman T.B.,University of Toledo |
Chaffin J.D.,University of Toledo |
Kane D.D.,Defiance College |
Conroy J.D.,Ohio State University |
And 3 more authors.
Journal of Great Lakes Research | Year: 2012
The Maumee River is an important source of phosphorus (P) loading to western Lake Erie and potentially a source of Microcystis seed colonies contributing to the development of harmful algal blooms in the lake. Herein, we quantified P forms and size fractions, and phytoplankton community composition in the river-lake coupled ecosystem before (June), during (August), and after (September) a large Microcystis bloom in 2009. Additionally, we determined the distribution and density of a newly emergent cyanobacterium, Lyngbya wollei, near Maumee Bay to estimate potential P sequestration. In June, dissolved organic phosphorus (DOP) was the most abundant P form whereas particulate P (partP) was most abundant in August and September. Green algae dominated in June (44% and 60% of total chlorophyll in river and lake, respectively) with substantial Microcystis (17%) present only in the river. Conversely, in August, Microcystis declined in the river (3%) but dominated (32%) the lake. Lake phytoplankton sequestered <6% of water column P even during peak Microcystis blooms; in all lake samples <112μm non-algal particles dominated partP. Lyngbya density averaged 19.4gdrywt/m 2, with average Lyngbya P content of 15% (to 75% maximum) of water column P. The presence of Microcystis in the river before appearing in the lake indicates that the river is a potential source of Microcystis seed colonies for later lake blooms, that DOP is an important component of early summer total P, and that L. wollei blooms have the potential to increase P retention in nearshore areas. © 2011 Elsevier B.V.