Environ Manage (2007) 39:526-533 DOI 10.1007/s00267-005-0155-9

Phosphorus Loadings Associated with a Park Tourist Attraction: Limnological Consequences of Feeding the Fish

Andrew M. Turner Æ Nathan Ruhl

Received: 24 May 2005 / Accepted: 18 August 2006 Springer Science+Business Media, Inc. 2007

Abstract The Linesville spillway of Pymatuning State added 48% to the non-point source watershed P enter- Park is one of the most visited tourist attractions in ing the lake. Park visitors feeding fish at the Linesville , USA, averaging more than 450,000 Spillway are a significant source of nutrients entering visitors year–1. Carp (Cyprinus carpio Linnaeus) and Sanctuary Lake. waterfowl congregate at the spillway where they are fed bread and other foods by park visitors. We Keywords Eutrophication Nutrient enrichment hypothesized that the ‘‘breadthrowers’’ constitute a Phosphorus loading Visitor impacts Carp significant nutrient vector to the upper portion of Pymatuning Reservoir. In the summer of 2002, we estimated phosphorus loadings attributable to bread- Introduction throwers, and compared these values to background loadings from Linesville Creek, a major tributary to the Managers of local, state, and national parks are under upper reservoir. Items fed to fish included bread, considerable pressure to maximize the number of park donuts, bagels, canned corn, popcorn, corn chips, hot visitors, as high visitation rates stimulate local econo- dogs, birthday cakes, and dog food. Phosphorus load- mies and provide justification for sustained funding. ing associated with park visitors feeding fish was However, parks are also charged with protecting the estimated to be 3233 g day–1, and estimated P export natural resources that attract visitors in the first place, from the Linesville Creek watershed was 2235 gday–1. and these two goals are sometimes in conflict P loading attributable to breadthrowers exceeded that (Goodwin 1996, Hammitt and Cole 1998). Visitors of the entire Linesville Creek watershed on 33 of the 35 can have a number of negative effects on park days of study, with only a heavy rainfall event ecosystems, and an important aspect of park manage- triggering watershed exports that exceeded spillway ment is the identification and assessment of visitor contributions. Averaged across 5 weeks, breadthrowers impacts (Sun and Walsh 1998). Some sorts of visitor- contributed 1.45-fold more P to Pymatuning Reservoir related problems, such as trail erosion, traffic conges- than the Linesville Creek watershed. If Linesville tion, and waste management, are easily identified (e.g., Creek P exports are extrapolated to the entire Sanc- Marion and Farrell 2002). Other effects of visitation tuary Lake watershed, spillway contributions of P are more subtle, less appreciated, and too often go unaddressed. In particular, the effects of park visitors on ecosystem-level processes such as nutrient cycling A. M. Turner (&) Department of Biology, Clarion University, Clarion, are not visually apparent and thus are often not Pennsylvania 16214, USA considered. However, perturbations to ecosystem level e-mail: [email protected] functions can trigger large-scale disruptions to the ecological functions of a protected area. In order to N. Ruhl Department of Biological Sciences, University, manage and mitigate the effects of visitation on park Athens, Ohio 45701, USA resources, managers must learn to identify and

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bread is bound up in organic forms, but microbial activity results in the metabolism of organic material and remineralizes P, making it available to support plant growth. Excessive phosphorus loadings can result in blooms of nuisance or toxic algae, low water clarity, hypoxia, fish kills, loss of biological diversity, and increased likelihood of invasion by exotic species (Carpenter and others 1998, Smith 1998). Phosphorus enrichment is a leading cause of surface water impairment in the United States (U.S. EPA 1996), because it limits the use of water for drinking, recreation, agriculture, and industry. Because of the detrimental effects of phos- phorus on aquatic ecosystems, point source discharges of P into surface waters are limited and regulated by state and federal laws, including the Federal Clean Water Act of 1972.

Study System

Pymatuning Reservoir, Pennsylvania’s largest inland lake (surface area = 6645 ha), consists of three distinct basins: Sanctuary Lake, Middle Lake, and Lower Lake (Figure 1). Pymatuning Reservoir was formed in 1934 Fig. 1 Map of Pymatuning Reservoir, showing Linesville when the headwaters of the were spillway, Sanctuary Lake, Middle Lake, Lower Lake, the lower impounded by a dam built at Jamestown, PA. At the portion of Linesville Creek, and the boundaries of Pymatuning same time, another dam was built to separate Sanctu- State Park. Linesville spillway is the outlet from Sanctuary Lake, and drains into Middle Lake ary and Middle Lakes, and water drains over the Linesville spillway from Sanctuary Lake into Middle evaluate all visitor impacts, not just the visually Lake and thence into Lower Lake before exiting the obvious ones. Here we report on a common tourism reservoir via the Shenango River. practice that may degrade water quality, with the goal Based on limnological parameters measured in the of increasing the awareness of such problems so they summer of 2002 (Table 1), as well as previous inves- can be more readily identified and corrected. tigations of Pymatuning Reservoir (Tryon and Jackson The Linesville spillway of Pymatuning State Park, 1952, Hartman and Graffius 1960, U.S. EPA 1975) and Pennsylvania, USA, is one of the most visited tourist traditional limnological criteria (Carlson 1977, Wetzel attractions in the region, averaging more than 450,000 2001), Sanctuary Lake and Middle Lake are both visitors each year (Linda Armstrong, Pymatuning State hypereutrophic, but Sanctuary Lake is even more Park, personal communication). Water from the productive than is Middle Lake. Water column P uppermost basin of Pymatuning Reservoir, Sanctuary concentrations are very high and water clarity is low in Lake, passes over the spillway into the Middle Basin of both lakes. We focused our investigations on phospho- the lake (Figure 1). Since shortly after the reservoir rus because Pymatuning Reservoir has a N:P molar was created in 1934, large numbers of fish (mostly ratio >16:1 in late spring and early summer, and thus is common carp, Cyprinus carpio L.) and waterfowl have likely P limited during this time (U.S. EPA 1975, congregated at the spillway where they are fed bread A. Turner unpublished data). and other foods by park visitors. Casual observations There are a number of nutrient sources to suggest that quite large quantities of food are dumped Pymatuning Reservoir. The basins are shallow and into the lake each day, with the typical visiting family unstratified, and thus sediment resuspension and other carrying along several loaves of bread to feed the fish. forms of internal loading are likely important. The These foods, like all organic material, contain phos- watershed is largely agricultural, and thus watershed phorus (P), commonly a limiting nutrient in lakes. loading is likely significant. Both the Linesville sewage Much of the phosphorus is bread is in the form of treatment plant and the Linesville fish hatchery calcium phosphates. A portion of the phosphorus in discharge effluent into Sanctuary Lake. A large

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Table 1 Limnological parameters for Sanctuary Lake and June 30 through August 3, 2002. Estimates of Middle Lake basins of Pymatuning Reservoir Linesville Creek P exports were based on daily Parametera Sanctuary Lake Middle Lake measurements of stream discharge and collections of water samples for analysis of phosphorus concentra- b TP 295–623 lg/L 203–234 lg/L tions. Because P concentrations of stream water tended Secchi Disk 0.2 m 0.5–0.8 m –1 c to increase during high flows, we estimated P exports Kd (m ) 6.8 2.9 Chlorophyll ad 4.7–133 lg/L 10.3–62.5 lg/L over the course of the study as the sum of the daily POMe 13–46 mg/L 9.0–42 mg/L product of discharge and stream water P concentration. pH 7.7–9.1 8.1–9.2 f Our study site was approximately 500 m upstream Alkalinity (CaCO3) 79 mg/L 70–75 mg/L Conductivityg 188 lS/cm 160–197 lS/cm from the mouth of Linesville Creek and immediately Mean depth 1.6 m 3.2 m upstream of the Linesville sewage treatment plant Surface area 8.1 km2 34.7 km2 (Figure 1). Except during high flow periods, stream Hydraulic residence time 0.41 yr. 1.50 yr discharge was measured at a semipermanent station Watershed areah 75.3 km2 176.1 km2 with smooth flow through a confined reach. We a Most parameters were measured on two or more occasions estimated discharge from measurements of stream during June and July, 2002, and the range of values is shown width along with depth and velocity measurements at b TP = total phosphorus concentrations of surface grab samples, six stations placed 30 cm apart across the width of the measured after a persulfate oxidative digestion c stream. Total phosphorus concentration of stream Kd is the vertical attenuation coefficient of photosynthetic active radiation water samples was measured by subjecting the samples d Chlorophyll a samples were filtered through a GF/F filter, ex- to a persulfate oxidative digestion followed by color- tracted with ethanol, and analyzed using standard fluorometric imetric analysis (Perkin-Elmer Lambda 20 spectropho- methods tometer) using the ascorbic acid–molybdate blue e POM = particulate organic material, measured as the ash-free method (Strickland and Parsons 1972, APHA 1998). dry mass of material retained by a GF/F glass fiber filter, also We estimated phosphorus loadings associated with from surface grab samples f spillway breadthrowers by measuring the amount of Alkalinity was measured with methyl-orange method. bread thrown per visitor, the number of spillway g Conductivity is adjusted to 25C visitors, and the phosphorus content of bread: h Watershed areas include lake surface area, and Middle Lake watershed area includes the Sanctuary Lake watershed ðgP=dayÞ¼ðvisitors=dayÞðg bread=visitorÞ ð1Þ number of resident Canada geese (Branta canadensis ðgP=g breadÞ Linnaeus) reside on the lake and make a significant contribution to the overall P budget (U.S. EPA 1975). Phosphorus content of bread is well documented, We hypothesized that the ‘‘breadthrowers’’ may and we used published sources including the USDA constitute a significant nutrient vector to the upper Food and Nutrition Information Center (http:// portion of Pymatuning Reservoir. To our knowledge, www.nal.usda.gov/fnic/). Phosphorus is a constituent however, there are no existing studies of recreational of the organic compounds in plant seed tissue from fish feeding that would inform an assessment of the which bread is made, but it is also added as a salt environmental impact of this practice (but see Wolos preservative to commercially prepared breads (e.g., and others 1992 and Arlinghaus and Mehner 2003 for dicalcium phosphate, diammonium phosphate). Differ- an analysis of phosphorus loadings associated with carp ent sorts of bread vary in P content, and our mean angling). Therefore, we estimated phosphorus loadings P value is weighted by the observed proportions attributable to breadthrowers at the Linesville spillway. thrown at the spillway. For reference, we measured phosphorus exports from Determination of mass of bread thrown per visitor Linesville Creek, the largest stream discharging into was based on direct observations of randomly selected Sanctuary Lake. Linesville Creek has a watershed area spillway visitors (n = 346 visitors) conducted in July 2 of 25.2 km (34% of the overall Sanctuary Lake 2002. Food items other than bread were frequently fed watershed), and is predominantly agricultural. to fish, and these were noted, but this material was not included in our calculations. Methods We used repeated counts of cars in the spillway parking lot to estimate daily visitation because Spillway phosphorus loadings and Linesville Creek censusing cars was more efficient than censusing phosphorus exports were estimated each day from individual visitors. Using a simple steady-state model,

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Table 2 Key parameters used to estimate daily P loading at Linesville spillway P content of bread Bread thrown per person (n = 346)a Daily visitation (n = 35)b Daily P loading

1.08 mg/ g 1084 g (± 122 g)c 2747 (± 233)c 3233 g (± 563 g)c a Bread thrown per person is averaged across the 346 individuals observed b Daily visitation is the number of people who feed fish at the spillway each day, and is averaged across the 35 days of study c Standard deviation of mean, estimated with Monte Carlo simulation, is shown in parentheses hourly car counts (Ci) were converted into estimates of we used an average P content weighted by the visitation by taking into account the average residence proportions of different bread types thrown, yielding time of visitors (r), and average number of passengers a mean of 1.08 mg/g (Table 2). The product of these per car (p): model parameters is an average phosphorus loading X estimate of 3.23 kgday–1 and estimated loads over Daily visitation ¼ ðCi=rÞ p ð2Þ 5 weeks totaling 113.1 kg. The standard deviation of daily P loading estimates yielded by repeated model The number of vehicles in the spillway parking lot runs was 563 g, 17% of the estimated mean. was estimated from hourly censuses (174 observations Daily loads varied from a low of 1.49 kg on July 3 to over 35 days for an average of 5.0 observations/day, a high of 7.93 kg on July 6 (Figure 2). Temporal trends missing hourly values fit with linear interpolation showed a clear tendency for feeding activity to peak on between counts). The average duration of visit weekends (Figure 2), with P loading on weekends and –1 –1 (r = 0.47 hr, n = 47 observations) and the average holidays averaging 5.15 kgday , but just 2.23 kgday number of visitors per vehicle (p = 3.1 passengers / car; on weekdays. n = 346 cars observed) were measured through direct observation. Linesville Creek We conducted a Monte Carlo simulation in order to estimate the error associated with our model estimate Median daily discharge of Linesville Creek was 3 –1 of P loading. For each model parameter (P content of 3828 m day , and phosphorus content of streamwater bread, bread thrown per visitor, daily visitation), we averaged 72 lg/L. However, discharge increased more generated a set of input values by randomly sampling a than 10-fold after rainfall events, and stream P normal distribution with mean and standard deviation concentration was positively correlated with discharge, drawn from the distribution of the sample means. We so most of the P exports occurred after heavy rainfall. lack replicate observations for the P value of bread, so In fact, 83% of the Linesville Creek P exports we assumed a standard deviation equal to 10% of the measured over 5 weeks occurred in 1 day after very mean. We then conducted 50,000 model runs, and then heavy rainfall (July 28 and 29). A weather-reporting calculated the standard deviation of the resulting station near Linesville reported 3.7 cm of rain over the estimated mean P loads.

100000 Breadthrowers Results Linesville Creek a d /

Spillway P Loading P 10000 g ( g n i

Spillway visitation averaged 2747 people per day over d

a) 1000 the course of the study (Table 2). Our observations l s u revealed that spillway visitors fed a variety of items to r o

h 100

fish during the study period, including bread, donuts, p s bagels, canned corn, popcorn, corn chips, hot dogs, o h birthday cakes, and dog food. Considering only the Po y 10 bread portion of the feeding activity, each visitor threw 30-June 7-July 14-July 21-July 28-July 4-Aug an average of 1084 g of bread into the lake (Table 2); –1 83% of this total was white bread, with wheat, rye, and Fig. 2 Daily phosphorus loading (g P day ) to Pymatuning Reservoir attributable to tourists feeding bread to fish at the corn bread making up the remainder. Because the Linesville spillway in summer 2002. Daily phosphorus exports phosphorus content of bread depends on bread type, from Linesville Creek watershed are shown for reference

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48-hr period. On July 29, discharge peaked at rate (Lall 1991, Kibria and others 1998, Jahan and 235,525 m3day–1, and P concentrations rose to 276 others 2003, Niesar and others 2004), making a precise lgL–1, for a calculated export of 65 kg over a 24-hr estimate of retention difficult. Furthermore, a portion period. Phosphorus exports from the Linesville Creek of absorbed P is lost through excretion via the kidneys watershed averaged 2235 gday–1, and exports over 5 and gills (Jahan and others 2001). Niesar and others weeks totaled 78.2 kg. Given a watershed area of (2004) found that for carp fed a range of diets, 2 25.2 km , the estimated phosphorus export coefficient P retention ranged from 3.6% to 32.1%, with the for the watershed is 32.4 mgm–2year–1, a value quite lowest retention efficiencies associated with low typical of agricultural drainages. Thus, even though our P content food types (see also Jahan and others estimate of P exports was heavily influenced by a storm 2001). The P content of bread is lower than any of event, the resulting estimate is a robust value for the foods tested by Jahan and others (2001) or Niesar reference purposes. and others (2004), suggesting that most (>90%) P added to Pymatuning Reservoir becomes biologically available within a short time. Phosphorus retained by Discussion the carp is immobilized for the lifetime of the fish, and P fixed in the skeleton is slow to remineralize even Our study shows that fish feeding by park visitors can after the death of the fish (Kitchell and others 1975, potentially result in substantial environmental degra- 1979). Nevertheless, a portion of the P sequestered by dation. Averaged across time, breadthrowers contrib- fish will eventually be remineralized and add to overall uted 1.45-fold more P to Pymatuning Reservoir than lake nutrient loads unless the fish is somehow removed did the Linesville Creek watershed. P loading attrib- from the lake. Although there is a limited sport fishery utable to breadthrowers exceeded that of the Linesville targeting carp in Pymatuning Reservoir, most anglers Creek watershed on 33 of the 35 days of study, with practice catch and release, so angling likely does not only a heavy rainfall event triggering watershed constitute a significant loss of P from the system. exports that exceeded spillway contributions. If the In sum, because the P retention efficiency of carp areal export rates measured for the Linesville Creek feeding on bread is quite low, short-term net input of watershed are extrapolated to the entire Sanctuary P is not substantially less than gross P input, and a Lake watershed, spillway contributions of P contribute portion of the assimilated P will become biologically an additional 48% above the total non-point source available over longer time scales. watershed loads of P to the lake during the course of We chose to focus on bread and ignore other sorts of our study. We note, however, that we lack a compre- food additions to the lake because we had relatively hensive nutrient budget for Sanctuary Lake, making few observations of addition rate for these other foods evaluation of the biological importance of the addi- and thus our estimates of the P loading associated with tional P at the scale of the entire lake difficult. The lake other foods would have had low precision because of is quite eutrophic, because there are several large point small sample size. The additional foods added to the sources of P to the lake, including a fish hatchery and lake, however, contain significant amounts of phos- sewage treatment outflow. In addition, the sediments phorus, and their omission would contribute to an of the lake become anoxic in summer, creating condi- underestimate of the true amount of P added at the tions favorable for significant internal P loading. Thus, spillway. even though spillway contributions of P are large relative to the measured watershed inputs, they may Is the Phosphorus Added Biologically Important? well be dwarfed by other sources of P. Lacking a P budget for Sanctuary Lake, the overall effect of fish In the absence of a P budget, it is difficult to resolve the feeding on water quality cannot be known with any extent to which spillway-derived P has an effect on certainty. water quality in Sanctuary Lake. In a more general There are several potential errors that stem from the sense it is possible, however, to determine whether use of a relatively simple model of P loading. We have anthropogenic inputs of the magnitude measured here estimated gross P input, but some portion of the bread have the potential to degrade water quality in a lake of thrown to the fish will be ingested, absorbed, and this size. The eutrophication models of Vollenweider retained by carp, resulting in a lower net P input. Our (Vollenweider and Dillon 1974, Vollenweider 1976) observations suggest that ingestion efficiency is can be used to assess the effect of increased P loading relatively high, but retention efficiency varies widely on water quality. Following these models, a critical depending on food quality, temperature, and feeding loading, defined as the P loading rate beyond which

123 Environ Manage (2007) 39:526-533 531 an oligotrophic lake will become mesotrophic, can be and other essential nutrients in their diet, so con- calculated with a knowledge of mean depth and sumption of low-protein food such as bread may stunt mean hydraulic retention time (e.g., the loading growth or cause other health problems for the fish plot of Vollenweider 1975). Using such data for (Niesar and others 2004, Arlinghaus and Niesar 2005). Sanctuary Lake (Table 1) yields a critical loading of Wild fish, however, may be able to meet their 160 mg Pm–2yr–1. Assuming 450,000 visitors per nutritional requirements by supplementing their diet annum, the spillway contributes 530 kg P each year with natural foods. to Sanctuary Lake. Standardized by the area of The feeding activity at the Linesville spillway also Sanctuary Lake (8.1 · 106 m2), spillway P loading is attracts a sizable flock of waterfowl, mostly resident 65 mgm–2yr–1, which by itself is 41% the critical giant Canada geese (B. canadensis). Because Canada loading rate. Thus, there is clearly the potential for fish geese feed largely in terrestrial habitats but take refuge feeding to have significant effects on water quality in on water, they may constitute a significant nutrient lakes the size of Sanctuary Lake. vector into lakes (Manny and others 1994, Post and Perhaps the most useful way to view the issue is to others 1998, Kitchell and others 1999). Ferris and Jones express spillway P loading (or any other point-source (2003) evaluated the role of resident Canada geese in effluent) in terms of ‘‘watershed equivalents.’’ transporting phosphorus into Sanctuary Lake. Based A watershed equivalent is the watershed area that on direct observations of goose population size, activity would export an amount of material equivalent to the patterns, and defecation habits along with published observed point source discharge. Using the data of the accounts of goose manure phosphorus content, they 1975 EPA study (U.S. EPA 1975), the mean export estimated P loading attributable to geese in Sanctuary coefficient for the entire Pymatuning watershed was Lake of 320–1200 g Pday–1, similar to the daily P estimated to be 38.9 kg Pkm–2yr–1. This figure agrees exports from Linesville Creek. The EPA study of 1973 with our own study of Linesville Creek, where we (U.S. EPA 1975) also cited the resident Canada geese found that P exports extrapolated to a full year would as a water quality concern. be 32.4 kg Pkm–2yr–1 (assuming that export rates did not change seasonally), and with published studies A Solution to the Problem? of phosphorus export coefficients from mixed farmland/forest watersheds (ca. 35 kg P km–2 yr–1; Bread sales at the Linesville spillway, handled by a Dillon and Kirchner 1975, Wetzel 2001). Using 35 kg private concessionaire, were replaced with catfish Pkm–2 yr–1 as a working value, the spillway contribu- food pellets in summer 2003. Although this shift has tion would be equivalent to that of 15.1 km2 of somewhat reduced the unsightly and unseemly habit Pymatuning Reservoir watershed, or roughly the same of park visitors throwing human food into a public as the P loading of a typical small stream to the lake. waterway, it has not addressed the root problem of Excessive P loading can switch lakes over to water quality degradation. The spillway concession- nitrogen limitation, and there is some evidence that aire estimates food sales of more than 500 kg on a Pymatuning Reservoir is reaching this threshold. N:P busy day (personal communication). Phosphorus con- molar ratios in Sanctuary Lake and Middle Lake are tent of catfish food is 0.8%, 8.5-fold higher than that >16:1 in late spring and early summer, but fall to <10:1 of white bread. Thus, current P loads from fish food in late summer (U.S. EPA 1975, A. Turner personal alone may exceed 4000 g day–1 (a large portion of the observation). Portions of Middle Lake suffer from tourists continue to supply their own bread). More profuse growth of N-fixing blue–green algae (Cyano- generally, it seems unlikely that the switch to the bacteria) in the late summer. Seasonal shifts from P to P-enriched fish food has been accompanied by an 8.5- N limitation are evidence that the lake is becoming P fold reduction in amount of food fed to fish, so the saturated because of excessive loadings of phosphorus. overall result of this conversion has likely been to We have measured oxygen concentrations within elevate the already problematic P loading to Pyma- carp feeding aggregations in order to assess whether tuning Reservoir. carp activity results in localized oxygen depletion and The effect of fish feeding on water quality can be hypoxia. Midday oxygen concentrations fell from a moderated in some cases by regulating the types of background level of 9–10 mgL–1 to less than 2.0 food fed to the fish. For example, Arlinghaus and mgL–1 where carp densities exceeded 1.0 fishm–2 (A. Niesar (2005) show that various foods typically fed to Turner and S. Montgomery, unpublished data). Carp carp differ substantially from each other in P content density within feeding aggregations at the Linesville and retention and suggest that the most ecologically spillway often exceeds 6 fishm–2. Carp require protein sound foods are those with the lowest P content (see

123 532 Environ Manage (2007) 39:526-533 also Jahan and others 2001, Niesar and others 2004). cational efforts could be devised with the goal of In the case of Pymatuning Reservoir, however, the educating visitors about the various threats to water bread predominantly fed to fish has a P content that is quality. The most difficult step in implementing any sort very low relative to alternate foods (Table 2). Thus, P of public education program is generating an interested enrichment of the reservoir is driven by the quantity of audience, and the Linesville spillway attraction pro- food added to the lake, not the quality, and any effort vides a large captive audience each day. By developing to moderate the impact of fish feeding on water quality educational resources at the site, park managers would at Pymatuning State Park should focus on limiting the be taking best advantage of the lure of the carp. amount of food fed to fish. Acknowledgments Students enrolled in the 2002 Limnology course at the Pymatuning Laboratory of Ecology (PLE) initiated Conclusion this study as a class research project and collected much of the data presented here. Thanks to the class: Vince Cummins, Chad Eisenman, Sarah Hudson, Ken Lee, Michael Sawicki, Mike In the 1930s when tourists began feeding fish at the Spence, Sari Sullivan, and Crystal Vangura. Sharon Linesville spillway, animals were commonly fed within Montgomery, Chuck Williams, Mark Orams, and several parks, and such activities were popular tourist attrac- anonymous reviews commented on the manuscript. We thank April Randle for maintaining the PLE water lab, Stephen Tonsor tions. However, biologists and park managers have for his encouragement, and the PLE staff for their help. The come to recognize that it is inappropriate for humans to Archbold Biological Station provided logistical support during interact with wildlife by feeding them, because this manuscript preparation. Financial support was provided by poses a number of dangers to both wildlife and humans. Clarion University’s College of Arts and Sciences and by the National Science Foundation. Well-known problems associated with feeding wildlife and the resulting aggregation of animal populations at feeding stations include aggression toward humans, References malnutrition, dependency, transmission of disease, and environmental degradation (Orams 2002). For these APHA (American Public Health Association, American Water reasons, managers of public lands generally discourage Works Association & Water Environment Federation) (1998) Standard methods for the Examination of Water or prohibit the feeding of wild animals, and decades of and Wastewater, 20th ed. American Public Health Associ- education have sought to inform the public of the ation, Washington, DC detrimental effects of such practices (Mallick and Arlinghaus R, Mehner Y (2003) Socio-economic characterisation Driessen 2003). Curiously, however, the practices of of specialised common carp (Cyprinus carpio L.) anglers in feeding fish continue in some instances, as does the Germany, and implications for inland fisheries management and eutrophication control. Fisheries Res 61:19–33 feeding of waterfowl, perhaps under the presumption Arlinghaus R, Niesar M (2005) Nutrient digestibility of angling that the problems associated with feeding other wildlife baits for carp, Cyprinus carpio, with implications for species do not apply to these taxa. groundbait formulation and eutrophication control. Fisher- Our study demonstrates that fish-feeding activity by ies Manage Ecol 12:91–97 Carlson RE (1977) A trophic state index for lakes. Limnol park visitors has the potential for local degradation of Oceanogr 22:361–369 the aquatic ecosystem. This sort of visitor impact is not Carpenter SR, Caraco NF, Correll DL, Howarth RW, visually obvious, yet has large-scale and persistent Sharpley AN, Smith VH (1998) Nonpoint pollution of ecosystem level effects. Lakes, streams, and rivers are surface waters with phosphorus and nitrogen. Ecol Applic 8:559–568 especially vulnerable to disruptions of nutrient cycles, Dillon PJ, Kirchner WB (1975) The effects of geology and land because they are preferred recreational sites, but are use on the export of phosphorus from watersheds. Water sensitive to even small perturbations of biogeochem- Res 9:135–148 ical cycles. Park managers need to consider such Ferris GK, Jones JL (2003) Waterfowl as nutrient vectors: A case study of the role of Canada Geese in transporting phospho- disruptions to ecosystem level processes when evalu- rus into lakes. Proceedings, Fall American Fisheries Society ating visitor impacts. meeting, Clarion, PA Outright prohibition of feeding fish by park visitors Goodwin H (1996) In pursuit of ecotourism. Biodiversity would likely be unpopular and unpalatable to park Conserv 5:277–291 Hammitt WE, Cole DN (1998) Wildland recreation: ecology and managers. The 450,000 people that visit the Linesville management, 2nd ed. John Wiley & Sons, New York spillway each year are a powerful testament, however, Hartman RT, Graffius JH (1960) Quantitative seasonal change to the innate curiosity of humans regarding fish and in the phytoplankton communities of Pymatuning aquatic ecosystems. The presence of so many curious Reservoir. Ecology 41:333–340 Jahan P, Watanabe T, Satoh S, Kiron V (2001) Formulation of park visitors presents a valuable opportunity to low phosphorus loading diets for carp (Cyprinus carpio L.). implement educational efforts. Exhibits or other edu- Aquaculture Res 32(suppl 1):361–368

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