Entrainment Of Ichthyoplankton Research Articles

The Ohio River Ecological Research Program (ORERP): History and Accomplishments

The Ohio River Ecological Research Program (ORERP), sponsored by multiple power plants along the river's main stem, was in existence for 50 years. Its goals were to collect fish community data to evaluate possible impacts to Ohio River fish communities because of either power plant discharges (i.e., thermal effects) or cooling water intakes. Studies by the ORERP have shown that thermal avoidance of discharge areas often occurs during the summer, but this avoidance is temporary and reversible, and long‐term disruptions of the fish communities have not been detected. Impingement studies conducted at 13 plants from 2005 to 2007 showed that impingement was highly episodic and dominated by clupeids and Freshwater Drum Aplodinotus grunniens. Impinged fish were mainly (>90%) young of the year; as a result, impingement numbers strongly reflected year‐class strength. Entrainment of ichthyoplankton was conducted under the ORERP at seven plants in 2015 and 2016. Annual entrainment estimates ranged from 43 million to 3.5 billion (i.e., 3.5 × 109) ichthyoplankton depending on the plant. The principal benefit of this collaborative effort was that these data allowed the sponsoring facilities and others to access an extensive database upon which fact‐based regulatory, resource management, and plant operating decisions could be based. Most importantly, the ORERP is a collaborative model for private and public organizations to collect, share, and analyze data and make resource management decisions for a large, multi‐use aquatic resource.

Using Forward and Backward Particle Tracking Approaches to Analyze Impacts of a Water Intake on Ichthyoplankton Mortality in the Appomattox River

Municipal intakes of surface water have various uses, and their impacts on the aquatic environment and ecosystem, such as the impingement and entrainment of ichthyoplankton, are a major concern. A robust assessment of the intake impacts on ichthyoplankton in a system generally requires modeling efforts that can simulate the transport and dispersal pathways of the ichthyoplankton. However, it is challenging to simulate hydrodynamics with a high-resolution grid at the scale needed for intake screen sizes in a large system. In this study, a 3D unstructured grid model with a fine resolution grid (<1 m) was developed to investigate potential impacts of an intake on aquatic resources in a tidal freshwater estuary. This approach enables us to directly estimate intake-induced mortality. With the use of the coupled particle-tracking model, we evaluated the total and maximum daily removal rates of particles by the intake that can be used to estimate percent mortality of ichthyoplankton. We further investigated how impacts from the intake vary with spawning locations, flow conditions, and vertical migration velocity of ichthyoplankton. A risk assessment was conducted based on designed flow of water withdrawals. This approach is widely applicable and can address impacts of water intakes in other systems.

Evaluation of the Zone of Influence and Entrainment Impacts for an Intake Using a 3-Dimensional Hydrodynamic and Transport Model

Ballast water systems in large LNG carriers are essential for proper operations and stability. Water withdrawn from the surrounding environment to supply to the ballast can pose entrainment and impingement risk to the resident fish population. Quantification of these risks and the net effect on population is usually quite challenging and complex. Various methods over the last several decades have been developed and are available in the literature for quantification of entrainment of mobile and immobile lifestages of resident fish. In this study, a detailed 3-dimensional model was developed to estimate the entrainment of ichthyoplankton (fish eggs and larvae) and fish from an estuarine environment during the repeated short-term operation of a ballast water intake for an LNG carrier. It was also used to develop a zone of influence to determine the ability of mobile life stages to avoid impingement. The ichthyoplankton model is an Equivalent Adult Model (EAM) and assesses the number of breeding adults lost to the population. The EAM incorporates four different methods developed between 1978 and 2005. The study also considers the uncertainty in estimates for the lifestage data and, as such, performs sensitivity analyses to evaluate the confidence level achievable in such quantitative estimates for entrainment.

Methodology for Predicting Cooling Water Effects on Fish

The mathematical model presented here predicts the long-term effects of once-through cooling water systems on local fish populations. The fish life cycle model simulates different life stages of fish by using appropriate expressions representing growth and mortality rates. The heart of the developed modeling approach is the prediction of plant-caused reduction in total fish population by estimating recruitment to adult population with and without entrainment of ichthyoplankton and impingement of small fish. The model was applied to a local fish species, gilthead (Sparus aurata), for the case of a proposed power plant in the Aegean region of Turkey. The simulations indicate that entrainment and impingement may lead to a population reduction of about 2% to 8% in the long run. In many cases, an impact of this size can be considered rather unimportant. In the case of sensitive and ecologically valued species facing extinction, however, necessary precautions should be taken to minimize or totally avoid such an impact.

Entrainment of lchthyoplankton by a Warmwater Hydroelectric Facility

Abstract We examined entrainment of ichthyoplankton associated with hydropower generation in 1988 and 1989 at the Pensacola Dam hydroelectric facility on Grand Lake in northeastern Oklahoma. To provide a basis for evaluating the effects of entrainment on the fish assemblage, we also estimated the total abundance of fish eggs and larvae in the top 10 m of the reservoir. Entrainment totaled about 10 million larval fish in 1988 and almost 100 million in 1989. Only nine taxa of larval fish were entrained during the study. Entrained eggs were almost exclusively those of freshwater drum Aplodinotus grunniens. Although estimates of entrainment were large, they were generally low compared with the estimates of total abundance of ichthyoplankton in Grand Lake.

Revised Estimates of Power Plant Entrainment of Ichthyoplankton in Western Lake Erie in 1975–77

Previous estimates of larval production and power plant entrainment, distributed over four power plants, are revised using a lumped parameter method by which power plant mortality is estimated independently of natural mortality. Using the method, mean daily power plant entrainment of four species of ichthyoplankton averaged over three seasons of production (1975–77) ranged from zero to 7.6 percent. These estimates are statistically consistent with earlier estimates made by a more laborious, distributed parameter technique.

Simulating the Lateral Transport of Ichthyoplankton in the Potomac Estuary

Previous simulations of potential ichthyoplankton entrainment by power generating stations on the Potomac estuary have not included the influence of lateral transport in distributing eggs and larvae over the nursery area. Therefore, two-dimensional, vertically-averaged hydrodynamic and kinematic models of passive organism transport were developed to represent advective and dispersive processes near the proposed Douglas Point Nuclear Generating Station. Although the more refined model did not substantially alter the estimate of ichthyoplankton entrainment, it did reveal that lateral inhomogeneities in hydrodynamics could engender severalfold differences in entrainment probabilities on opposite sides of the estuary. Models of higher resolution and greater biological detail did not project greater total entrainment by the Douglas Point plant, because the volume of nontidal flow past the site was large in comparison to the proposed rate of cooling water withdrawal.

Impact of Power Plant Entrainment of Ichthyoplankton on Juvenile Recruitment of Four Fishes in Western Lake Erie in 1975–77

The effect of power plant entrainment on juvenile recruitment of four species of ichthyoplankton in western Lake Erie was investigated. Of the four species studied—gizzard shad ( Dorosoma cepedianum), white bass ( Morone chrysops), walleye ( Stizostedion vitreum) and freshwater drum ( Aplodinotus grunniens)—it was found that the effect on walleye year class strength is minimal while the effect on gizzard shad recruitment may possibly be significant in terms of overall impact on the community ecology of the western basin. This aspect of the impact of power plant entrainment should be further investigated. It was estimated that total juvenile recruitment of these four species would increase by 742 individuals per acre if all power plant entrainment were eliminated.

Comparison of a High Volume Pump and Conventional Plankton Nets for Collecting Fish Larvae Entrained in Power Plant Cooling Systems

A high volume pump (2.5 m3/min capacity at 6 m head) and conventional plankton nets (0.5 and 1.0 m diam) were operated side by side in two tests to evaluate the efficiency of each gear for sampling fish larvae within the intake structure of a coastal power plant. At intake channel current velocities up to 40 cm/s (the maximum tested), the pump in one test caught significantly more fish larvae than the nets. Compared to the pump, both sizes of plankton nets in each test greatly undersampled large larvae (over 5.0 mm total length). Our findings suggest that conclusions regarding ichthyoplankton entrainment based on data obtained with conventional plankton nets may be of questionable validity. Key words: ichthyoplankton, entrainment, pump, nets