Geology topics

Karin Limburg

Publications and source records attributed to Karin Limburg.

5 recordsLinked to original sources

USGS2025

Tourists or residents? Life history strategies of Rainbow Smelt in Lake Champlain

Objective Rainbow Smelt Osmerus mordax are the most important native prey fish in the coldwater food web of Lake Champlain, but their history in the lake is not well understood. Writers in the 1800s described a nonresident population of smelt that reached sizes greater than 315 mm that was sympatric with a population of individuals that matured at smaller sizes. No studies, however, have investigated mechanisms that cause the dimorphic size structure of Rainbow Smelt in Lake Champlain. Based on our results, larger fish appear to have life history strategy differences from most of the population, which allow them to grow to larger sizes, faster. We proposed three alternative hypotheses to explain the presence of these large Rainbow Smelt in Lake Champlain: (1) anadromous and landlocked Rainbow Smelt may both be present in the lake, (2) all Rainbow Smelt may be landlocked with the two morphotypes resulting from different diet preferences and/or differences in environmental niche occupancy, or (3) the largest Rainbow Smelt are long-lived and therefore had longer time for growth. Methods We tested these hypotheses using otolith microchemistry, diet (stomach content and stable isotope), and age analyses. Our length-at-age analyses showed that age structure was not bimodal, but there are fish present in the lake as large as those in the 1800s. Results Microelemental analysis indicated that Rainbow Smelt in Lake Champlain were landlocked, with no marine signature. Stomach contents of average-sized Rainbow Smelt were exclusively zooplankton and macroinvertebrates, while the larger Rainbow Smelt were primarily piscivorous and had greater δ 15 N values, which suggests a higher trophic position. A combination of hypotheses 2 and 3 most likely explains current population structure. Elevated manganese : magnesium ratios in larger Rainbow Smelt suggest that they may utilize a hypoxic environmental niche, a potential key life history strategy allowing for faster growth, suggesting that there may be intraspecific variation in how Rainbow Smelt use the basins of Lake Champlain. Conclusions Based on our results, larger fish appear to have life history strategy differences from most of the population that allow them to grow to larger sizes, faster. Future studies are needed to uncover the nuances of the mechanisms for growth.

New York, Vermont↗

USGS2022

Tracking fish lifetime exposure to mercury using eye lenses

Mercury (Hg) uptake in fish is affected by diet, growth, and environmental factors such as primary productivity or oxygen regimes. Traditionally, fish Hg exposure is assessed using muscle tissue or whole fish, reflecting both loss and uptake processes that result in Hg bioaccumulation over entire lifetimes. Tracking changes in Hg exposure of an individual fish chronologically throughout its lifetime can provide novel insights into the processes that affect Hg bioaccumulation. Here we use eye lenses to determine Hg uptake at an annual scale for individual fish. We assess the widely distributed benthic round goby ( Neogobius melanostomus ) from the Baltic Sea, Lake Erie, and the St. Lawrence River. We aged layers of the eye lens using proportional relationships between otolith length at age and eye lens radius for each individual fish. Mercury concentrations were quantified using laser ablation inductively coupled plasma mass spectrometry. The eye lens Hg content revealed that Hg exposure increased with age in Lake Erie and the Baltic Sea but decreased with age in the St. Lawrence River, a trend not detected using muscle tissues. This novel methodology for measuring Hg concentration over time with eye lens chronology holds promise for quantifying how global change processes like increasing hypoxia affect the exposure of fish to Hg.

Environmental Science and Technology↗

USGS2020

Cryptic lives of conspicuous animals: Otolith chemistry chronicles life histories of coastal lagoon fishes

Bar-built coastal lagoons are dynamic ecosystems at the land-sea interface that are important habitats for a variety of species. This study examined the habitat ecology of two lagoon species, the endangered Tidewater Goby ( Eucyclogobius newberryi ) and the Prickly Sculpin ( Cottus asper ) by reconstructing individual life histories from patterns in the concentration of the element Sr (as ratioed to Ca; Sr:Ca) in otoliths. Specific objectives were to (1) elucidate any movements of individual fishes among three primary habitat components of typical bar-built lagoon systems: coastal ocean, brackish lagoon, and freshwater watershed streams, and (2) determine if either species exhibited a consistent life history as defined by a stereotypical otolith Sr:Ca chronology, which could be indicative of a consistent range of salinity or temperature occupied through ontogeny. Results suggested that Tidewater Goby was a lagoon resident and that Prickly Sculpin exhibited migrations between lagoon and watershed stream habitats. There was no strong evidence in either species of ocean occupancy or of a stereotypical Sr:Ca chronology, the latter suggesting the full range of available lagoon habitat in terms of salinity and temperature was likely utilized at all life stages. These findings add to the body of evidence that bar-built lagoons are not isolated habitats, and holistic management of these habitats with adjoining watershed and marine environments could increase habitat connectivity across the landscape, with potential benefits to fishes.

California↗

USGS2020

Lifetime chronicles of selenium exposure linked to deformities in an imperiled migratory fish

Aquatic ecosystems worldwide face growing threats from elevated levels of contaminants from human activities. Toxic levels of selenium (Se) shown to cause deformities in birds, fish, and mammals can transfer from parents to progeny during embryonic development or accumulate through Se-enriched diets. For migratory species that move across landscapes, tracking exposure to elevated Se is vital to mitigating vulnerabilities. Yet, traditional toxicological investigations resolve only recent Se exposure. Here, we use a novel combination of X-ray fluorescence microscopy and depositional chronology in a biomineral to reveal for the first time provenance, life stage, and duration of toxic Se exposure over the lifetime of an organism. Spinal deformities observed in wild Sacramento Splittail ( Pogonichthys macrolepidotus ), an imperiled migratory minnow, were attributed to elevated Se acquired through maternal transfer and juvenile feeding on contaminated prey. This novel approach paves the way for diagnosing sources, pathways, and potential for a cumulative exposure of Se relevant for conservation.

California↗

USGS2014

Comparative biogeochemistry-ecosystem-human interactions on dynamic continental margins

The ocean’s continental margins face strong and rapid change, forced by a combination of direct human activity, anthropogenic CO 2 -induced climate change, and natural variability. Stimulated by discussions in Goa, India at the IMBER IMBIZO III, we (1) provide an overview of the drivers of biogeochemical variation and change on margins, (2) compare temporal trends in hydrographic and biogeochemical data across different margins (3) review ecosystem responses to these changes, (4) highlight the importance of margin time series for detecting and attributing change and (5) examine societal responses to changing margin biogeochemistry and ecosystems. We synthesize information over a wide range of margin settings in order to identify the commonalities and distinctions among continental margin ecosystems. Key drivers of biogeochemical variation include long-term climate cycles, CO 2 -induced warming, acidification, and deoxygenation, as well as sea level rise, eutrophication, hydrologic and water cycle alteration, changing land use, fishing, and species invasion. Ecosystem responses are complex and impact major margin services including primary production, fisheries production, nutrient cycling, shoreline protection, chemical buffering, and biodiversity. Despite regional differences, the societal consequences of these changes are unarguably large and mandate coherent actions to reduce, mitigate and adapt to multiple stressors on continental margins.

Journal of Marine Systems↗