Geology topics

Research about Connecticut River

Source-linked reports with geographic coverage including Connecticut River.

11 recordsLinked to original sources

USGS2025

Quality assessment of past spawning mark estimations from a long-term survey in the Connecticut River watershed

The calcified structures of fishes provide insight into their periodic growth rates and can be combined with other biological variables to identify metrics such as size or age at maturity and mortality rates. Collecting this information on growth and life history can help evaluate the success of conservation efforts and inform future management decisions for a species in need. However, before these life history data can be applied to larger stock assessments that direct management decisions, confidence in the validity of the data needs to be reported through metrics of accuracy and precision. For this report, we assessed the bias and precision of paired reader estimations of spawning marks on scales of Blueback herring (Alosa aestivalis) collected in the U.S. Fish & Wildlife (USFWS) Annual Adult River Herring Stock Assessment for the lower Connecticut River basin. The paired reads on scales from a total of 8,698 fish over the ten years of the long term monitoring program were evaluated for the annual presence of systematic bias and precision using a combination of qualitative (i.e., frequency tables) and quantitative (i.e., Evan’s and Hoenig’s Test of Symmetry, and Coefficient of Variation (CV) calculations) analyses. While seven out of the ten survey years had systematic bias detected by the tests of symmetry, only three years (2013, 2016, 2018) had imprecision values >10% CV threshold. Data were further categorized into specific age classes within survey years to increase our resolution on where bias and imprecision was most prevalent. While the ability for accurate bias detection was limited by sufficient sample sizes (>25 fish), average imprecision values increased with age, and median age classes (4 through 6) commonly had bias detected. However, the removal of insufficient age classes prior to calculating average annual CV did not significantly change the initial average. Lastly, 2023, which was the first year to implement a standardized training procedure prior to production estimating, had the highest precision for both the annual average and specific age classes compared to all prior survey years. This standardized training procedure will continue to be used by USFWS for the lower Connecticut River tributaries, and can be modified for other river systems. Overall, this report’s results highlight the importance of assessing precision and encourage the standardization of spawning mark identification quality control and assurance for future studies. With more quality assessments and baseline information on precision and bias, there can be more beneficial discussion on defining thresholds and how to implement spawning history variability into catch curve analyses.

Connecticut, Massachusetts↗

USGS2021

Export of photolabile and photoprimable dissolved organic carbon from the Connecticut River

Dissolved organic carbon (DOC) impacts water quality, the carbon cycle, and the ecology of aquatic systems. Understanding what controls DOC is therefore critical for improving large-scale models and best management practices for aquatic ecosystems. The two main processes of DOC transformation and removal, photochemical and microbial DOC degradation, work in tandem to modify and remineralize DOC within natural waters. Here, we examined both the photo- and microbial remineralization of DOC (photolability and biolability), and the indirect phototransformation of DOC into biolabile DOC (photoprimed biolability) for samples that capture the spatiotemporal and hydrological gradients of the Connecticut River watershed. The majority of DOC exported from this temperate watershed was photolabile and the concentration of photolabile DOC correlated with UV absorbance at 254 nm ( r 2 = 0.86). Phototransformation of DOC also increased biolability, and the total photolabile DOC (sum of photolabile and photoprimed biolabile DOC) showed a stronger correlation with UV absorbance at 254 nm (r 2 = 0.92). We estimate that as much as 49% (SD = 3.3%) and 10% (SD = 1.1%) of annual DOC export from the Connecticut River is directly photolabile and photoprimable, respectively. Thus, 2.82 Gg C year −1 (SD = 0.67 Gg C year −1 ) or 1.13 Mg C km −2 year −1 (SD = 0.27 km −2 year −1 ) of total photolabile DOC escapes photochemical degradation within the river network to be exported from the Connecticut River each year.

Connecticut River↗

USGS2020

Modeling larval American Shad recruitment in a large river

Climate change is altering the spatial and temporal patterns of temperature and discharge in rivers, which is expected to have implications for the life stages of anadromous fish using those rivers. We developed an individual-based model to track American Shad Alosa sapidissima offspring within a coarse template of spatially and temporally variable habitat conditions defined by a combination of temperature, river velocity, and prey availability models. We simulated spawning at each river kilometer along a 142-km reach of the Connecticut River on each day (April 1–August 31) to understand how spawning date and location drive larval recruitment differentially across years and decades (1993–2002 and 2007–2016). For both temperature and flow, interannual variation was large in comparison to interdecadal differences. Variation in simulated recruitment was best explained by a combination of season-specific spawning temperature and location along the course of the river. The greatest potential recruitment occurred during years in which June temperatures were relatively high. In years when June and July were warmer than average, maximum recruitment resulted from spawning taking place at the upstream portion of the modeled reach. Model scenarios (stationary or passive-drift larvae; and dams or no dams) had predictable effects. We assumed that the pools above dams had negative impacts on eggs and yolk-sac larvae that may have been deposited there. Allowing eggs and larvae to drift passively with the current reduced spatial differences in recruitment success among spawning sites relative to stationary eggs and larvae. Our results demonstrate the importance of spatiotemporal environmental heterogeneity for producing positive recruitment over the long term. In addition, our results suggest the importance of successful passage of spawners to historical spawning sites in the Connecticut River upstream of Vernon Dam, especially as conditions shift with climate change.

New Hampshite, Massachutsetts↗

USGS2019

Push and pull of downstream moving juvenile sea lamprey (Petromyzon marinus) exposed to chemosensory and light cues

Visual and olfactory stimuli induce behavioural responses in fishes when applied independently, but little is known about how simultaneous exposure influences behaviour, especially in downstream migrating fishes. Here, downstream moving juvenile sea lamprey ( Petromyzon marinus ) were exposed to light and a conspecific chemosensory alarm cue in a flume and movement were monitored with overhead cameras and nets. When exposed to light, sea lamprey were more likely to be captured in a net closest to the light array. When exposed to the alarm cue, sea lamprey transit rate through the flume increased, but sea lamprey did not avoid the alarm cue plume by moving perpendicular to flow. When the alarm cue and light were applied simultaneously in a push and pull configuration, the alarm cue still triggered enhanced downstream movement (push downstream) and more sea lamprey was still captured in the net nearest the light (pull to the side), resulting in twice as many sea lamprey being captured in the lighted net relative to controls. To our knowledge, this is the first study using multiple sensory cues in a push-pull configuration to modulate fish outmigration. Push and pull of juvenile sea lamprey with sensory cues could be useful to reduce turbine entrainment where native and enhance trap catch where invasive.

Massachusetts↗

USGS2018

Nitrogen concentrations and loads for the Connecticut River at Middle Haddam, Connecticut, computed with the use of autosampling and continuous measurements of water quality for water years 2009 to 2014

The daily and annual loads of nitrate plus nitrite and total nitrogen for the Connecticut River at Middle Haddam, Connecticut, were determined for water years 2009 to 2014. The analysis was done with a combination of methods, which included a predefined rating curve method for nitrate plus nitrite and total nitrogen for water years 2009 to 2011 and a custom rating curve method that included sensor measurements of nitrate plus nitrite nitrogen concentration and turbidity along with mean daily flow to determine total nitrogen loads for water years 2011 to 2014. Instantaneous concentrations of total nitrogen were estimated through the use of a regression model based on sensor measurements at 15-minute intervals of nitrate plus nitrite nitrogen and turbidity for water years 2011 to 2014. Annual total nitrogen loads at the Connecticut River at Middle Haddam ranged from 12,900 to 19,200 metric tons, of which about 42 to 49 percent was in the form of nitrate plus nitrite. The mean 95-percent prediction intervals on daily total nitrogen load estimates were smaller from the custom model, which used sensor data, than those calculated by the predefined model. Annual total nitrogen load estimates at the Connecticut River at Middle Haddam were compared with the upstream load estimates at the Connecticut River at Thompsonville, Conn. Annual gains in total nitrogen loads between the two stations ranged from 3,430 to 6,660 metric tons. These increases between the two stations were attributed to the effects of increased urbanization and to combined annual discharges of 1,540 to 2,090 metric tons of nitrogen from 24 wastewater treatment facilities in the drainage area between the two stations. The contribution of total nitrogen from wastewater discharge between the two stations had declined substantially before the beginning of this study and accounted for from 31 to 52 percent of the gain in nitrogen load between the Thompsonville and Middle Haddam sites.

Connecticut↗

USGS2014

Migratory patterns of hatchery and stream-reared Atlantic salmon Salmo salar smolts in the Connecticut River, U.S.A.

The timing of downstream migration and detection rates of hatchery-reared Atlantic salmon Salmo salar smolts and stream-reared smolts (stocked 2 years earlier as fry) were examined in the Connecticut River (U.S.A.) using passive integrated transponder (PIT) tags implanted into fish and then detected at a downstream fish bypass collection facility at Turners Falls, MA (river length 192 km). In two successive years, hatchery-reared smolts were released in mid-April and early May at two sites: the West River (river length 241 km) or the Passumpsic (river length 450 km). Hatchery-reared smolts released higher in the catchment arrived 7 to 14 days later and had significantly lower detection rates than smolts stocked lower in the catchment. Hatchery-reared smolts released 3 weeks apart at the same location were detected downstream at similar times, indicating that early-release smolts had a lower average speed after release and longer residence time. The size and gill Na + /K + -ATPase (NKA) activity of smolts at the time of release were significantly greater for detected fish (those that survived and migrated) than for those that were not detected. Stream-reared pre-smolts (>11·5 cm) from four tributaries (length 261–551 km) were tagged in autumn and detected during smolt migration the following spring. Stream-reared smolts higher in the catchment arrived later and had significantly lower detection rates. The results indicate that both hatchery and stream-reared smolts from the upper catchment will arrive at the mouth of the river later and experience higher overall mortality than fish from lower reaches, and that both size and gill NKA activity are related to survival during downstream migration.

Connecticut, Massachusetts, Rhode Island, Vermont↗

USGS2014

Salt‐water intrusion in the Connecticut River

The intrusion of salt water in the lower Connecticut River Basin was studied during October 1, 1934, to June 30, 1939. The field‐ and laboratory‐work was done as a project of the Works Progress Administration under the sponsorship of the State Water Commission of the State of Connecticut. Some technical assistance was given by the Geological Survey through cooperation with the State Water Commission.

Connecticut↗

USGS2010

Modeling migratory energetics of Connecticut River American shad ( Alosa sapidissima ): implications for the conservation of an iteroparous anadromous fish

We present a simulation model in which individual adult migrant American shad ( Alosa sapidissima ) ascend the Connecticut River and spawn, and survivors return to the marine environment. Our approach synthesizes bioenergetics, reproductive biology, and behavior to estimate the effects of migratory distance and delays incurred at dams on spawning success and survival. We quantified both the magnitude of effects and the consequences of uncertainty in the estimates of input variables. Behavior, physiology, and energetics strongly affected both the distribution of spawning effort and survival to the marine environment. Delays to both upstream and downstream movements had dramatic effects on spawning success, determining total fecundity and spatial extent of spawning. Delays, combined with cues for migratory reversal, also determined the likelihood of survival. Spawning was concentrated in the immediate vicinity of dams and increased with greater migratory distance and delays to downstream migration. More research is needed on reproductive biology, behavior, energetics, and barrier effects to adequately understand the interplay of the various components of this model; it does provide a framework, however, that suggests that provision of upstream passage at dams in the absence of expeditious downstream passage may increase spawning success — but at the expense of reduced iteroparity.

Connecticut, Massachusetts, New Hampshire, Vermont↗

USGS2004

Summary of water quality trends in the Connecticut River, 1968-1998

The Connecticut River has a long history of water quality impairment. From the 1800s to the late 1960s, untreated or minimally treated waste discharges from population centers and industries have caused serious water quality problems. Trend analysis of selected water quality data in Connecticut from 1968 to 1998, collected by the U.S. Geological Survey in cooperation with the Connecticut Department of Environmental Protection, shows that water quality has improved, benefiting aquatic plants and animals, recreation, and the esthetics of the river. Many of the trends detected—including downward trends in total phosphorus, total nitrogen, and indicator bacteria, and upward trends in pH and dissolved oxygen—can be attributed primarily to improvements in wastewater treatment following the Federal Clean Water Act of 1972. Some uncertainty remains in evaluating the environmental significance of trends in dissolved oxygen, pH, and other constituents with diurnal fluctuations caused by plant metabolism. Downward trends in sulfate concentrations likely are attributable to reductions in sulfur dioxide emissions mandated by the Clean Air Act of 1970 and amendments made in 1990. Upward trends in chloride concentrations illustrate some effects of increasing urbanization and nonpoint-source pollution. Current (2003) and future water quality challenges for the Connecticut River include reducing nitrogen loads from point and nonpoint sources, reducing bacteria and other contaminant concentrations in urban stormwater runoff, and separating stormwater and sanitary sewers at some locations to prevent combined-sewer overflows.

Connecticut↗

USGS1990

Soil-vegetation correlations in the Connecticut River floodplain of Western Massachusetts

As part of a national study analyzing the relation between hydric soils and wetland vegetation, the vegetation associated with a series of known soils was sampled along the Connecticut River floodplain in Massachusetts. Weighted average and index average (presence/absence) values were calculated for vegetation using wetland ecological index values from the National List of Plant Species that Occur in Wetlands developed by the U.S. Fish and Wildlife Service and procedures developed by T. R. Wentworth and G. P. Johnson at North Carolina State University. Good correspondence between soils and vegetation was recorded with two exceptions. Two typically nonhydric soils were determined to be hydric based on vegetation analyses. Examination of the groundwater hydrology of these two soils confirmed their hydric nature. The authors suggested that one of these soils may need to be redefined and they also suggested that the assigned index values for a few species of vegetation should be reexamined. However, in general the index average values of vegetation based on published wetland index values corresponded with the hydric and nonhydric nature of soils.

Massachusetts↗

USGS1977

Availability of ground water in the lower Connecticut River basin, southwestern New Hampshire

This map scale 1:125,000 presents a preliminary assessment of the availability of ground water in the lower Connecticut River basin in southwestern New Hampshire. It is a generalization of several hydrogeologic factors and provides a guideline for ground-water exploration useful in water- and land-use planning. It does not describe the absolute quantity or quality of ground water available. The best aquifers in the basin are deposits of stratified sand or sand and gravel of Pleistocene age. Large aquifers of this type occur in places in the Connecticut River valley and in valleys of tributaries to the Connecticut River. Ground water is generally of good chemical quality. Iron and manganese in concentrations greater than the recommended limits for drinking water suggested by the U.S. Public Health Service are not uncommon. (USGS).

New Hampshire↗