Journal of Great Lakes Research最新文献

The genome of vertebrates is made of a mosaic of long stretches of DNA, called isochores, which are compositionally uniform, and belong to a few families of GC-poor (L1 and L2) and GC-rich (H1, H2, and H3) components. Poikilotherms tend to have GC-poor genomes, while endotherms comprise both GC-poor and GC-rich isochores. The thermal theory claimed that temperature and natural selection played an active role in favoring GC-rich genomic regions, yet empirical evidence was difficult to obtain. Early work based on cesium chloride ultracentrifugation gradients showed that the Lake Magadi tilapia, a hot-water adapted fish species, displayed GC-rich regions that were absent from a close relative that lives in colder water. The goal of this study was to revisit the original study using full genome sequencing. We found that the original GC-rich regions are indeed present, that they are interspersed in the genome. Indeed, when comparing Lake Magadi tilapia with the temperate Nile tilapia, we found that 59.3 % of the genome of Lake Magadi tilapia had a base composition higher than 40 %GC, as opposed to 55.3 % of the genome of the Nile tilapia having a base composition higher than 40 % GC. We also found that their genomes comprised similar amounts of repetitive elements (20 % and 19.5 %, respectively) indicating that the shifts in base composition might not be due to repetitive elements. Further work on repetitive element analyses, protein coding genes and additional hot-water adapted fishes will provide clues as to the origin of GC-rich isochores in Lake Magadi tilapia.

Pontederia crassipes, one of the most invasive aquatic plants in the world, in recent years began to spread in East Europe, as was anticipated by species distribution models. We have documented P. crassipes on the eastern shore of the Black Sea (Pitsunda town), the only area potentially suitable for P. crassipes under the current climate conditions, according to the modeling, where the species has not been registered yet in nature until now. The revealed location is situated in the Colchis, an important refugium and global biodiversity hotspot. As the species has strong negative impact on biodiversity, monitoring of the Pitsunda population and, if it appears to be established, its eradication is crucial. Continuous monitoring of water systems in East Europe, Caucasus and even Siberia is essential to detect further spread and possible establishment of P. crassipes.

The 2003 collapse of alewives (Alosa pseudoharengus) has allowed lake-wide recruitment of wild lake trout (Salvelinus namaycush) for many consecutive years in the main basin of Lake Huron, but the loss of this major pelagic prey fish also raised concerns about the carrying capacity of the lake for lake trout rehabilitation. In this paper, size-at-age data for individual lake trout from the 2003 and more recent year-classes were analyzed, and the additive effects of age, year-class, and sampling year were estimated and compared using a linear-mixed model. After declines to a very low level following the collapse of alewives, lake trout size-at-age recovered during the late 2000 s and early 2010 s, and then stabilized, although the new level was not as high as that in the pre-2003 time-period with abundant alewives and rainbow smelt (Osmerus mordax). Lake Trout size-at-age also did not maintain a meaningful difference between northern and southern Lake Huron. Furthermore, the total length and body mass of wild lake trout were smaller at ages 2–4 than that of stocked lake trout. The differences became insignificant at ages 5–6 and negligible at ages 7–19. The direct size-at-age comparisons between stocked and wild lake trout were different from the comparisons of growth parameters based on the von Bertalanffy growth function, suggesting that it is important to analyze actual size-at-age measurements and not to fully rely on the growth-parameter comparisons.

The Great Lakes region of North America is experiencing climate-driven disturbances that threaten the safety and livelihoods of coastal communities and people. Limitations to the spatial and temporal coverage of research have the potential to hamper the ability to predict site-specific conditions and responses to climatic events. In this paper, we contextualize these spatial and temporal limitations of climate change research. Our summary reveals an uneven spatial distribution of research across the basin and publication outlets, with research focused on Lakes Superior, Michigan, and Huron, and the increasing availability of biological and ecological data to forecast future conditions. The spatial and temporal limitations related to historical data, region-wide monitoring efforts, research during the winter season, and the technological and methodological developments in natural resource management that can overcome these limitations are explored. Future research and emerging data needs are discussed, including the need for increased inclusion of the social sciences and improving relationships with Indigenous and First Nation communities in terms of research, data sharing, and governance.

The North American Great Lakes have been experiencing dramatic change during the past half-century, highlighting the need for holistic, ecosystem-based approaches to management. To assess interest in ecosystem-based management (EBM), including the value of a comprehensive public database that could serve as a repository for the numerous physical, chemical, and biological monitoring Great Lakes datasets that exist, a two-day workshop was organized, which was attended by 40+ Great Lakes researchers, managers, and stakeholders. While we learned during the workshop that EBM is not an explicit mission of many of the participating research, monitoring, and management agencies, most have been conducting research or monitoring activities that can support EBM. These contributions have ranged from single-resource (-sector) management to considering the ecosystem holistically in a decision-making framework. Workshop participants also identified impediments to implementing EBM, including: 1) high anticipated costs; 2) a lack of EBM success stories to garner agency buy-in; and 3) difficulty in establishing common objectives among groups with different mandates (e.g., water quality vs. fisheries production). We discussed as a group solutions to overcome these impediments, including construction of a comprehensive, research-ready database, a prototype of which was presented at the workshop. We collectively felt that such a database would offer a cost-effective means to support EBM approaches by facilitating research that could help identify useful ecosystem indicators and management targets and allow for management strategy evaluations that account for risk and uncertainty when contemplating future decision-making.

In recent years, Lake Erie has seen a surge in harmful algal blooms, largely attributed to climatic changes and agricultural runoff in the Maumee River Watershed. These trends are shared in other watersheds across the Great Lakes and throughout the world. The actions of local citizens can improve local water quality, but action is unlikely to occur if the local community does not perceive problems with local water quality. While much of the literature focuses on how organoleptic properties (e.g., water quality is considered good if it smells and looks good) and demographic factors explain public perceptions, this study assesses more proximate indicators–including trust in those communicating about and managing water quality and pro-environmental values. We assess relationships among these variables among urban and rural residents in the Maumee River Watershed. Our results indicate that greater trust in agricultural organizations and local government was consistently associated with better perceived water quality. Future research should focus on how influential sources of information about water quality are presenting local water quality issues, as exploratory analyses support the idea that individuals with connections to agriculture, and affiliating as Republican, may be using a trust heuristic to assess local water quality. In other words, in the absence of actual metrics of water quality, beliefs about water quality may be formed based on who is most trusted. The results also indicate that assumptions about how a local community perceives local water quality can be based on particular identifying characteristics, such as political affiliation.

Warming water temperatures present challenges for ectotherms in freshwater ecosystems through influence on metabolic rate and bioenergetics. Diet, such as the inclusion of high energy prey, can reduce these influences, but accurate temperature profiles are key to improved predictions. Here, using the Wisconsin bioenergetics approach, we modelled lake trout (Salvelinus namaycush) and Chinook salmon (Oncorhynchus tshawytscha) growth for two time periods (present [2010–2019] and future 30-year (2041–2070) averaged scenarios) in Lake Ontario with in-situ observed year-round temperatures (obtained through acoustic telemetry and pop-off data storage tags deployed between 2016 and 2019) occupied by the species. For the future, we considered two water temperature scenarios (low and high, where experienced temperature increased by a mean of 0.4 °C and 1.0 °C, respectively) and the effects of a hypothetical diet switch with the inclusion of higher energy prey (bloater, Coregonus hoyi) currently being reintroduced. Under all forecasted warming conditions, lake trout performed well and growth was 41.3 to 82.5 % above present when bloater was re-incorporated in the diet up to 40 %. Chinook salmon maximum attainable growth declined between 11.2 and 29.6 % under forecasted warming scenarios without diet change. However, when bloater comprised ∼ 33 % of their diet, Chinook salmon growth increased 3.7 % under the low future scenario compared to present. These results demonstrate that impacts of future lake warming on predatory fish will vary with life-history characteristics of species and composition and abundance of prey base, and highlights the need for effective management that diversifies and conserves forage fish species in the Great Lakes.

Ancient lakes are known as biodiversity hotspots and provide unique opportunities to study diversity patterns. We compared the distribution and community characteristics of the meiofauna in the littoral (soft-substrate and hard substrates) and profundal (soft-substrate) of three ancient lakes situated in three different continents: Lake Baikal (Asia), Lake Ohrid (Europe), and Lake Malawi (Africa). We expected that, for microscopic creatures like meiofauna, community structure would be more influenced by local habitat features than by spatial distances between lakes. This was found for the deep profundal, a unique system not showing differences in meiofaunal abundance (about 500,000 ind. per m²) and biomass (about 100 mg dry weight per m²) across the lakes. But littoral communities differed across lakes in abundance (up to 7,000,000 ind. per m²) and biomass (on average 400 mg dry weight per m²).

The community structure was found to change significantly across the lakes and habitats, with distinct differences between profundal and littoral communities. Chironomids, copepods, and tardigrades were typical representatives of littoral communities, while nematodes dominated the profundal communities with >80 % of the individuals. Rotifers made up more than 50 % of the littoral hard substrate communities, while ostracods were more dominant in Lake Baikal. Abundance-biomass regressions of nematodes indicated significantly different trophic transfer efficiency and carrying capacity between profundal and littoral habitats, but no differences across the lakes. Nevertheless, this first comparative study of meiofauna in three ancient lakes revealed the need for more thorough investigations for a better understanding of these systems.

We investigated wetland vegetation before, during, and after dike construction at the Metzger Marsh project in western Lake Erie, which was designed to restore a 300-ha wetland that had been degraded following the loss of a protective barrier beach. A dike was constructed in 1995 to replace the function of the eroded barrier beach, but it contained a water-control structure to allow managed hydrologic connection to the lake. The control structure contained a fish passageway to allow movement of fish across the dike, while restricting entry of large common carp. Color-infrared aerial photos from project start in 1994 through 2010 (and 2022) were analyzed to track vegetation changes, and major vegetation types were sampled quantitatively. Drawdown of water levels in 1996 after dike construction elicited a response of mudflat species from the seed bank, as well as tree seedlings. Over half of the marsh was vegetated then and in subsequent years. The water-control structure was opened in 1998, and by 2000, invasive Phragmites australis had gained dominance. Most trees were eventually eliminated by herbicide treatment and flooding, and extent of Phragmites was reduced by management actions. Typha spp. and emergents Sagittaria latifolia and Schoenoplectus tabernaemontani became dominant by 2022. This restoration project increased habitat values for fish and wildlife; it also provided lessons for future projects on lands managed by multiple agencies with differing missions. More importantly, it showed that long-term monitoring data are critical for assessing wetland restoration projects and guiding management decisions.