Geology topics

Research about Michigan, New York

Source-linked reports with geographic coverage including Michigan, New York.

2 recordsLinked to original sources

USGS2022

Thiamine status of lake trout in lake Ontario and its relation to diet after the colonization of round goby, 2005–2006

A predominance of alewives ( Alosa pseudoharengus ), a species having high thiaminase activity, in Lake Ontario lake trout ( Salvelinus namaycush ) diets, has been related to thiamine deficiency in lake trout eggs during 1994–2004. The late 1990s invasion by round goby ( Neogobius melanostomus ), that appear to have thiaminase activity of low biological activity, represented a potential to reduce the dietary importance of alewife and, as a result, increase lake trout thiamine levels if they became sufficiently important in lake trout diets. To evaluate whether lake trout thiamine levels increased as alewives were displaced by round gobies in lake trout diets, we collected 199 lake trout ranging from 305 to 893 mm in 2005–2006 and measured their muscle thiamine levels and diet composition. Diet composition (percent by weight) was estimated from MixSIR based on stable isotopes (δ 15 N and δ 13 C) measured from lake trout and their prey. Overall, alewife and goby dominated lake trout diet (78%), with round goby dominating the diet (55–57%) of smaller individuals (<600 mm), and alewife dominating the diet (59–73%) of larger, reproductively active individuals. Lake trout muscle thiamine declined with increases in lake trout length and the proportion of alewife eaten (p < 0.01). The proportion of lake trout below 500 pmol/g thiamine also declined; this threshold is associated with a loss of equilibrium in adults. Despite the increasing albeit size-related consumption of round goby, it remains inadequate as muscle thiamine levels in mature lake trout (i.e., >600 mm) during 2005–2006 appear unchanged from levels observed in 1996.

Michigan, New York↗

USGS2021

Diversity in spawning habitat use among Great Lakes Cisco populations

Cisco ( Coregonus artedi ) once dominated fish communities in the Laurentian Great Lakes. Restoring the abundance and distribution of this species has emerged as a management priority, yet our understanding of Cisco spawning habitat use is insufficient to characterise habitat needs for these populations and assess whether availability of suitable spawning habitat could be a constraint to recovery. We characterised the distribution of incubating Cisco eggs in situ across gradients of depth and substrate types to describe the spawning habitat used by three Great Lakes populations. In Chaumont Bay, Lake Ontario, eggs were concentrated on shallow bedrock shoals and not found on deeper silt or sand substrate. In contrast, eggs in Thunder Bay, Lake Superior, and Elk Rapids, Lake Michigan, were found on deeper fine grain sediments with low utilisation of shallow rocky and cobble habitats. These patterns of egg incubation habitat use suggest a broad spawning habitat niche at the species level but distinct spawning habitat preferences at the population level. While our results indicate some historical diversity in spawning habitat use has been maintained across the species’ range in the Great Lakes, comparisons of contemporary spawning habitat utilisation against historical accounts raise questions as to whether some spawning habitat use behaviours may no longer be prevalent within specific lakes. Thus, characterising the portfolio of spawning strategies remaining within lakes may improve our understanding of habitat needs and identify opportunities to maintain population diversity while supporting Cisco rehabilitation.

Michigan, New York↗