North Twin Lake Research Articles

Zooplankton and profundal macroinvertebrate responses to hypolimnetic oxygenation in North Twin Lake, Washington

Cross BK, Taylor TN, Moore BC, Lanouette BP. 2021. Zooplankton and profundal macroinvertebrate responses to hypolimnetic oxygenation in North Twin Lake, Washington. Lake Reserv Manage. 37:275–288. Hypolimnetic oxygenation (HO) has been used to address lake eutrophication and fish habitat limitations, but details on zooplankton and profundal macroinvertebrate community responses are required to fully understand the trophic linkages and impacts. Compared to adjacent South Twin Lake (an unoxygenated reference), zooplankton and profundal macroinvertebrate densities and distributions were altered by HO in North Twin Lake. Overall, temporal trends in zooplankton density were similar between lakes despite oxygenation, suggesting annual and seasonal influences remained a primary factor affecting their density trends. During the day, Chaoborus density was significantly greater in the water column of unoxygenated South Twin Lake compared to oxygenated North Twin Lake (P < 0.0001) as the oxygenated hypolimnion no longer provided refuge from fish predation. Daphnia and copepod densities were greater in North Twin Lake during oxygenation compared to South Twin Lake (P = 0.0011 and P = 0.0005), which may reflect increases in zooplankton habitat availability and reduced predation from Chaoborus in response to HO. With higher levels of dissolved oxygen near the sediment–water interface in North Twin Lake, larval Chaoborus and chironomid densities in the benthic sediments were significantly higher compared to South Twin Lake (P < 0.0001 in both cases). Vertical distribution of zooplankton likely reflected some balance between habitat availability, energetic costs, and predation risk. Lakes with different fish species assemblages may not respond similarly, so managers should reflect on lake similarities between North Twin Lake and systems they manage to understand potential effects of HO and how those effects align with management objectives.

Peeping at Melville's Typee: Thoreau's Contact with "Dusky and Unexplored Nature"

Peeping at Melville's Typee:Thoreau's Contact with "Dusky and Unexplored Nature" Jake McGinnis (bio) Books can only reveal us to ourselves, and as often as they do us this service we lay them aside. —Henry David Thoreau Writing in his Journal in 1846, Henry David Thoreau describes a moment that rings with potent anticipation. It is his first of three trips to Maine, and his party is traveling upriver in a boat they call a "batteau," bound for Ktaadn. Having crossed North Twin Lake by moonlight and made camp on the far shore, they're now sleeping beneath their overturned boats, waking in turns to tend their log fire. Thoreau, rising alone sometime after midnight, rambles along the lakeshore in the dark, imagining the wilderness ahead and the wildlife that he might see there, his mind racing.1 This passage foreshadows the scene at the summit in "Ktaadn," when Thoreau would encounter a material wildness that he'd never anticipated, but, interestingly, this promise of new, wilder experiences to come doesn't last. When dawn breaks, the party prepares for another day of travel, and the text's focus suddenly shifts. Without explanation, Thoreau turns to consider Melville's first book, the recently published travel narrative, Typee: A Peep at Polynesian Life (1846): And we soon had launched and loaded our boat and were off again before breakfast. [End Page 223] Our appearance excited no bustle amid the surrounding hills as I read that when a ships boat approaches the bay o Typee one of the Marquesan isles the news is shouted from man to man—from the tops of cocoanut trees up the valley 8 or 9 miles, and soon its whole population is on the stir—stripping off the husks from Cocoa nuts—throwing down bread fruit—and preparing leafen baskets in which to carry them to the beach to sell. The young warrior may be seen polishing his spear and the maiden adorning her person for the occasion. I cannot help but be affected by the very fine—the slight but positive relation of the inhabitants of some remote isle of the Pacific to the mysterious white mariner. It is a barely recognised fact to the natives—that he exists and has his home far away somewhere and is glad to buy their fresh fruits with his superfluous commodities. (J, 315–16) Such a turn is unexpected in this otherwise mostly unswerving account of Thoreau's trip to Maine, a draft of what will become the essay "Ktaadn."2 Thoreau had read Melville's Typee, the American Revised edition, sometime in the late summer of 1846, and it left a trace not only in the Journal but also in the published versions of "Ktaadn" (1848), A Week on the Concord and Merrimack Rivers (1849), and Walden (1854).3 Why, though, turn to Typee when the promise for new experiences, for a vivid taste of the North Maine Woods, looms so large? Why turn to a novel that Thoreau's contemporaries considered somewhat scandalous? Further, what is the relationship between Typee and Thoreau's epiphany near the summit of "Ktaadn," the famous "Contact!" scene? [End Page 224] This essay addresses this striking shift from Maine to the Marquesas to the globe, from a party of white American travelers in Abenaki country, to white mariners in the Pacific, to a global network of cultural relations. Highlighting what Thoreau first seemingly elides—Typee's playful eroticism and thinly veiled interest in the homoerotic—I argue that Thoreau's use of Melville reflects an ongoing process of reimagining relationality and contact, in this case between a crew of bachelor sailors and a cast of mostly naked women. By surveying Thoreau's various drafts and literary projects, my analysis performs what John Bryant calls "fluid text" reading, wherein a text exists in multiple versions across space and time, each one reflecting various degrees of authorial, editorial, social, and cultural influence.4 In this case, "Ktaadn" gathers steam in the Journal in 1846 and appears in the Union Magazine of Literature and Art in 1848, but in a truly "fluid" fashion it trickles and drips into Thoreau's other work as...

Decreased oxygenation demand following hypolimnetic oxygenation

Gantzer PA, Preece EP, Nine B, Morris J. 2019. Decreased oxygenation demand following hypolimnetic oxygenation. Lake Reserv Manage. 35:292–307. We analyzed long-term oxygenation dynamics in 3 waterbodies: Spring Hollow Reservoir (SHR) and Carvins Cove Reservoir (CCR), which are water supply reservoirs, and North Twin Lake (NTL), a natural lake. Bubble plume line diffuser hypolimnetic oxygenation system (HOS) operation was for 13, 10, and 7 yr for SHR, CCR, and NTL, respectively. Water column profiles were measured in all 3 waterbodies. Additionally, remotely deployed sensors were used to monitor dissolved oxygen (DO) in NTL year-round, specifically to capture winter conditions during ice cover. Hypolimnetic oxygen demand (HOD) was observed to decrease after several years of HOS operation in all 3 waterbodies. Annual HOD decreased more for HOS operated year-round compared to recovery-based operation where HOS was started after DO decreased below 5.0 mg/L. Additionally, HOD throughout the summer stratified period was lower following maintenance of higher DO during spring prior to onset of stratification. An analogous result was observed during winter ice cover relative to DO conditions following fall turnover. Prior work showed increased HOD during HOS operation compared to pre-HOS. The increased HOD during HOS operation was termed diffuser-induced oxygen demand and implied the HOS was inducing oxygen demand. However, the current work shows HOS operation is not actually inducing oxygen demand; rather, it is addressing the existing oxygen demand already in the sediments. Our data suggest that a HOS is an effective tool to maintain hypolimnion DO in stratified lakes and reservoirs. When operated year-round or before DO decreases, HOS can decrease HOD and reduce overall long-term operational costs.

Using stable isotope analysis to assess the effects of hypolimnetic oxygenation on diet in a mixed cold- and warmwater fish community

Line-diffuser hypolimnetic oxygenation was initiated in North Twin Lake, Washington, in 2009 to mitigate reductions in Rainbow Trout (Oncorhynchus mykiss) and Brook Trout (Salvelinus fontinalis) habitat due to temperature-dissolved oxygen “habitat squeeze”. Previous studies demonstrated that trout populations rapidly expanded into increased hypolimnetic habitat within the first few years of oxygenation and previous short-term diet analyses indicated an effect on fish diet; however, the long-term effects on fish ecology have yet to be established. In this study, stable isotope analysis of fish liver tissue suggests relatively few differences in feeding ecology of principal coldwater fish species in North Twin Lake compared to unoxygenated South Twin Lake. When compared between lakes, Rainbow Trout and Brook Trout diets contained similar proportions of Daphnia, Chironomidae, and Chaoboridae. Littoral and epilimnetic-focused Golden Shiner (Notemigonus crysoleucas) diets were also similar between lakes. Observed similarities between Golden Shiner and trout diets suggest the effects of interspecific competition between salmonids and non-salmonids may be limiting trout growth and survival. Fisheries managers should therefore consider both habitat limitations and interspecific competition when managing for coldwater fish species in mesotrophic, dimictic lakes.

Hypolimnetic oxygenation effects on trout condition and growth in North Twin Lake, Washington

ABSTRACTCross BK, Moore BC, Skinner MM. 2017. Hypolimnetic oxygenation effects on trout condition and growth in North Twin Lake, Washington. Lake Reserve Manage. 33:74–83.Summer stratification can restrict coldwater fish habitat, but we did not observe increases in trout growth or body condition when hypolimnetic oxygenation was applied to improve habitat conditions. Our study investigated the effects of hypolimnetic oxygenation in North Twin Lake (oxygenated 2009–2015 from May through Sep) on rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) preferred habitat availability, abundance, body condition, and growth while using adjacent South Twin Lake as an unoxygenated reference. When assessing rainbow trout preferred habitat (dissolved oxygen ≥5 mg/L and temperature 13–19 C), oxygen levels were not limiting prior to oxygenation, and oxygenation did not increase preferred habitat availability. Trout abundance in both lakes remained comparable throughout oxygenation, but trout were able to move between lakes outside of summer months. Regardless of oxygenation, North Twin Lake had higher brook trout relative weights (i.e., body condition index) compared to South Twin (P = 0.0002), averaging 89.8 and 86.0, respectively. Rainbow trout relative weight differences were not observed between lakes before or during oxygenation (P = 0.1873). Prior to oxygenation, summer growth rates of rainbow trout were similar between North Twin and South Twin lakes (P = 0.9958). In 2012, growth rates of rainbow trout and brook trout in North Twin were not significantly different from South Twin (P = 0.8210 and P = 0.1474, respectively). Our results suggest that hypoxic conditions were not limiting trout growth or condition in North Twin Lake because preferred habitat volume and prey availability were not enhanced by hypolimnetic oxygenation.

Estimating in situ isotopic turnover in Rainbow Trout (Oncorhynchus mykiss) muscle and liver tissue

ABSTRACTStable isotope analysis (SIA) is a powerful tool for assessing food webs and diet. However, the underlying assumptions that stable isotope ratios in an organism's tissues reflect that of its present diet may be complicated by isotopic turnover and retention time. Quantification of in situ isotopic turnover of study organisms and different tissues via field studies is essential to inform scientifically sound food web and diet studies utilizing SIA. Rainbow Trout white muscle and liver tissue were collected monthly from North Twin Lake, Washington during the 2013 growing season. Using ANCOVAs, we estimated stable carbon retention time of 154 (95% CI: 106–224) and 292 (95% CI: 257–763) days for Rainbow Trout liver and white muscle, respectively. For nitrogen, we estimated a retention time of 186 (95% CI: 114–329) days for both white muscle and liver. Our analyses suggest longer isotopic retention times (and therefore slower isotope turnover rates) for adult fish in a natural system relative to those commonly reported in the literature. These findings can improve interpretation of SIA in future aquatic food web and diet studies involving adult coldwater fish in freshwater systems.

Effects of hypolimnetic oxygen addition on mercury bioaccumulation in Twin Lakes, Washington, USA

Twin Lakes, located on the Confederated Tribes of the Colville Indian Reservation in eastern Washington, USA, include North Twin Lake (NT) and South Twin Lake (ST). The mesotrophic, dimictic lakes are important recreational fishing sites for both warm-water bass and cold-water trout. To improve summertime cold-water habitat for trout in NT, dissolved oxygen (DO) addition to the hypolimnion, using liquid oxygen as an oxygen gas source, started in 2009. This study assessed mercury (Hg) in the water column, zooplankton and fish, and related water quality parameters, in Twin Lakes from 2009 to 2012. Because methylmercury (MeHg) buildup in lake bottom water is commonly associated with hypolimnetic anoxia, hypolimnetic oxygenation was hypothesized to reduce Hg in bottom waters and biota in NT relative to ST. Oxygen addition led to significantly higher DO (mean hypolimnetic DO: 2–8mg/L versus <1mg/L) and lower MeHg (peak mean hypolimnetic MeHg: 0.05–0.2ng/L versus 0.15–0.4ng/L) in North Twin. In North Twin, years with higher DO (2009 and 2011) exhibited lower MeHg in bottom waters and lower total Hg in zooplankton, inferring a positive linkage between oxygen addition and lower bioaccumulation. However, when comparing between the two lakes, Hg levels were significantly higher in zooplankton (total Hg range: 100–200 versus 50–100μg/kg dry weight) and trout (spring 2010 stocking cohort of eastern brook trout mean total Hg: 74.9 versus 49.9μg/kg wet weight) in NT relative to ST. Lower Hg bioaccumulation in ST compared to NT may be related to bloom dilution in chlorophyll-rich bottom waters, a vertical disconnect between the location of zooplankton and MeHg in the water column, and high binding affinity between sulfide and MeHg in bottom waters.

Hypolimnetic oxygenation in Twin Lakes, WA. Part II: Feeding ecology of a mixed cold- and warmwater fish community

Line-diffuser hypolimnetic oxygenation (HO) was initiated in North Twin Lake, Washington, in 2009 to mitigate loss of coldwater fishery habitat due to temperature–dissolved oxygen “habitat squeeze” and to reduce internal phosphorus cycling. Active tracking, net-captures, and hydroacoustic analyses demonstrated that trout populations rapidly expanded into increased hypolimnetic habitat within the first few years of oxygenation; however, long-term fishery benefits and many basic ecological aspects of HO have yet to be established. Diet and food web analyses indicate significant changes in feeding ecology of principal coldwater fish species in North Twin in 2012 compared to preoxygenation (2005) and to unoxygenated South Twin in 2012. North Twin rainbow trout (Oncorhynchus mykiss) consumed significantly more large-bodied Daphnia during midsummer 2012 than in South Twin, where rainbow trout fed primarily on littoral amphipods. Additionally, relative gut weight for brook trout (Salvelinus fontinalis) in August 2012 was significantly higher in North Twin compared to South Twin, apparently due to increased access to hypolimnetic zooplankton. Golden shiner (Notemigonus crysoleucas) diets also seem to include more zooplankton in oxygenated North Twin. Littoral-focused largemouth bass (Micropterus salmoides) diets were not altered by HO. Observed changes in feeding ecology following HO have significant implications for future fishery management in the Twin Lakes.

Response of methylmercury, total mercury, iron and manganese to oxygenation of an anoxic hypolimnion in North Twin Lake, Washington

This study evaluated the impact of oxygenation on the accumulation of methylmercury (MeHg), total mercury (Hg), iron (Fe), and manganese (Mn) in the anoxic hypolimnion of North Twin Lake, Washington (mean depth = 9.7 m). Within 8 hours of the start of the oxygenation test, mean hypolimnetic total Fe dropped from 833 to 243 μg/L (58% dissolved), and Mn decreased from 119 to 32 μg/L (100% dissolved). After 17 days of oxygenation, mean hypolimnetic total Hg decreased from 0.77 to 0.58 ng/L, and MeHg decreased from 0.20 to 0.10 ng/L. A month after the end of the oxygenation test, MeHg, total Hg, Fe, and Mn concentrations rebounded to pre-oxygenation levels. Metal dynamics were explained by the differing redox characteristics of Fe (fast oxidation kinetics; reduction at lower redox potential) and Mn (slow oxidation kinetics; reduction at higher redox potential) in natural waters, and the tendency for Fe oxides to co-precipitate with reduced Mn, ionic Hg, and MeHg. From a lake management perspective, the study highlights the role that oxidized metals in surfacial sediments play in retaining Hg in profundal sediments and suggests that sorption characteristics of metal oxides could be exploited to manage Hg bioaccumulation in aquatic biota. The study also suggests that for oxygenation to effectively repress the accumulation of redox-sensitive compounds in the hypolimnion, oxygenation systems should (1) start before anoxic conditions are established; (2) operate continuously through the entire stratified season; and (3) maintain oxygen levels at the sediment–water interface to ensure oxygen penetration into surfacial sediments.

Largemouth bass consumption demand on hatchery rainbow trout in two Washington lakes

High mortality (84–89%) of stocked rainbow trout (Oncorhynchus mykiss) in Twin Lakes, Washington, has been partially blamed on predation from non-native largemouth bass (Micropterus salmoides). We examined the gut-content of 434 largemouth bass and applied a bioenergetics model to determine the consumption demand on hatchery-released rainbow trout and other prey species in the Twin Lakes. Largemouth bass consumed approximately 4915 (95% CI; 2393–13,452) fall stocked rainbow trout in South Twin. No rainbow trout consumption was observed in North Twin, despite a similar stocking regime. Approximately 6.3% (95% CI; 3–17%) of total fall stocked rainbow trout in South Twin were consumed by largemouth bass. Rainbow trout stocked in the fall ranged from 100 to 160 mm total length and were all subject to predation by large largemouth bass ⩾300 mm. Large largemouth bass consumed rainbow trout that reached up to 210 mm in length and 58% of bass body length. No predation was observed on larger rainbow trout (215–370 mm) stocked during the spring. Smaller largemouth bass ⩽299 mm consumed primarily invertebrates, including crayfish, and did not consume rainbow trout in either lake. During spring and summer in South Twin Lake, large largemouth bass consumed principally golden shiner (Notemigonus crysoleucas) and crayfish. In North Twin Lake, golden shiner constituted most of the larger bass diet for the entire year. Differences in macrophyte distribution, bathymetry, temperature and/or predator-prey demographics likely influenced variability in largemouth bass predation between lakes. Largemouth bass predation did not account for overall rainbow trout mortality.

Widespread Distribution of the Non-Native Northern Crayfish (Orconectes virilis) in the Columbia River Basin

Abstract We report here the first records of the non-native northern crayfish (Orconectes virilis) in the Columbia River basin within Washington State. Confirmed occurrences include the reservoirs Lake Rufus Woods and Lake Roosevelt on the Columbia River, North Twin Lake in the upper Columbia River basin, Lake Patterson in the Methow River basin, Wapato Lake in the Lake Chelan basin, and Moses Lake in central Washington. Uncertainty remains as to the source, extent of current distribution, and potential impacts of these O. virilis populations. Release of live bait by anglers is a common pathway for crayfish introductions, although stocking for harvest or aquaculture and releases of pets or laboratory animals is equally likely for the introduction of O. virilis to the region. Evaluating potential impacts of O. virilis on native crayfish, fish, and other species in the Columbia River basin will require additional study. These newly discovered O. virilis populations are likely to naturally disperse further t...

Some factors regulating cohort production of the crayfish, Orconectes virilis

SUMMARY. Cohort production of the crayfish. Orconectes virilis, ranged from 148.8 to 70.2 kg in North Twin Lake (surface area 1.9 ha) and from 151.9 to 84.9 kg in West Lost Lake (surface area 1.4 ha). Both cohort production (P) and cohort mean biomass (B) showed a long‐term decrease with time. The cohort P/B ratios did not show such a trend but remained steady. The P/B ratio approximated the life cycle instantaneous rate of growth (G) which could then be used for estimating cohort production from mean biomass.Production remained consistently higher in West Lost Lake. Analysis of horizontal life table data revealed no inherent difference between survival and fecundity rates of the crayfish population in each lake. Slight differences in basin morphometry between the two lakes determined nursery habitat availability and this affected recruitment of young from each female brood stock. Small differences in carrying capacity between two similar sized nearby lakes, along with a decrease in carrying capacity over time, were sufficient to nullify attempts to manage these populations using a maximum sustainable yield model.

Crayfish Productivity, Allochthony, and Basin Morphometry

West Lost Lake has a higher production of the crayfish, Orconectes virilis, than does nearby North Twin Lake. The basis for the higher carrying capacity of West Lost Lake lies in its steeper basin slope which extends more of its littoral leaf fall distribution to the deeper waters where the social dominance of males forces the female adults to reside. As a result there is a greater available supply of allochthonous food provided for the female brood stock in West Lost Lake. Even though attached egg production per female breeder is the same in both lakes, more hatchlings are produced in West Lost because it has a greater density of nursery area provided by larger beds of Carex aquatilis var. substricta. Because the survival rate of crayfish throughout life is not different in the two lakes, the higher production in West Lost is attributed to a greater carrying capacity for both young and adults.Key words: crayfish production, basin morphometry, allochthonous import, Orconectes virilis

Results of an Experimental Fishery on the Crayfish Orconectes virilis

Populations of the crayfish Orconectes virilis were exploited using the Paulik–Bayliff modification of the Ricker model in two small lakes. After harvesting with traps at maximum sustained yield (MSY) for 3 yr, fishing effort was increased fourfold in one lake, West Lost, for two successive seasons, while in North Twin Lake it was not changed. In West Lost yields were stable during MSY; yields increased with overexploitation, but growth and recruitment declined. Distortions occurred in the age composition of the catch. In North Twin this pattern was repeated except that in 1975 the catch dropped drastically even though fishing effort had not been increased. Because of declining recruitment, North Twin was actually overfished by about 20% in 1974 and greatly overfished in 1975. Decreased recruitment in both lakes can be attributed to two factors: (1) a decreased survival of hatchlings in both lakes due to a decline in nursery habitat; as a consequence the stock-recruitment relationship was altered; and (2) an increase in the density of age I (subadult) females due to the selective fishery for males; as a result density-dependent mechanisms lowered the survival of females from age I to II, producing fewer spawning adults. However, the high density of these age II females at age I decreased the egg production per adult female. The changes in the productivity of the lakes for crayfish during the period of exploitation were related to loss of microhabitat for hatchlings. This change in productivity offset the benefits of MSY management and resulted in a drastic drop in stocks when deliberate overfishing took place. West Lost gave good yields prior to its certain collapse. Yields in weight were an unreliable indicator of the impact of the fishery. Key words: crayfish, Orconectes virilis, potential yield, production, recruitment, stock assessment, experimental fishery

Utilization of Plankton by Juvenile Gizzard Shad in a Shallow Prairie Lake

Irruptions of gizzard shad, Dorosoma cepedianum (Le Sueur), in North Twin Lake, Iowa in 1954 and 1955 provided opportunities for investigating certain basic ecological relationships of this species. Of the approximately 358 plankton species and varieties found in North Twin Lake, 260 were encountered in shad digestive tracts. On a volume basis, phytoplankton (primarily Cyanophyta and Chlorophyta) constituted the bulk of young-of-the-year and yearling gizzard shad food. Crustacean zooplankton were important food elements of recently hatched individuals. Rotifers and crustaceans were about equally abundant in the plankton and in gizzard shad digestive tracts, and a fair degree of relationship was found between the amounts of green algae and diatoms ingested by age 0 shad and the proportions of the same forms in the plankton. Yearling gizzard shad apparently select green algae. Blue-green algae were apparently not consumed in proportion to their relative abundance in the environment. Where the relatively scarce Microcystis aeruginosa appeared to be a selected item, the most abundant plankter, Aphanocapsa delicatissima, constituted comparatively small portions of gizzard shad foregut contents. Gizzard shad are capable of consuming relatively minute plankters, some commonly ingested forms being no larger than 20 microns in greatest dimension. Circumstantial evidence suggests that large shad populations may play a significant role in suppressing irruptions of objectionable algae. Where hatching periods overlap, feeding activities of newly hatched shad may adversely affect survival of the young game species through direct competition for crustacean plankton which both groups seem to require during early growth stages.