Novel molecular approach demonstrates that turbid river plumes reduce predation mortality on larval fish

Abstract

Turbidity associated with river plumes is known to affect the search ability of visual predators and thus can drive 'top-down' impacts on prey populations in complex ecosystems; however, traditional quantification of predator-prey relationships (i.e. stomach content analysis) often fails with larval fish due to rapid digestion rates. Herein, we use novel molecular genetic methods to quantify larval yellow perch (YP) in predator stomachs in western Lake Erie to test the hypothesis that turbidity drives variation in larval predation. We characterize predator stomach content DNA to first identify YP DNA (single nucleotide polymorphism) and then quantify larval YP predation (microsatellite allele counting) in two river plumes differing in turbidity. Our results showed elevated larval YP predation in the less turbid river plume, consistent with a top-down impact of turbidity on larval survival. Our analyses highlight novel ecological hypothesis testing using the power of innovative molecular genetic approaches.

Portfolio theory as a management tool to guide conservation and restoration of multi‐stock fish populations

“…For instance, large precipitation events that lead to enhanced discharge from and sediment concentrations in the Maumee and Sandusky rivers (Richards 1990, Richards et al 2008) may negatively affect larval walleye production in the rivers proper through scouring effects (Mion et al 1998). However, sediment laden plumes may simultaneously benefit larval walleye production on the open-lake reefs by providing nutrient-rich, turbid waters that offer both ample foraging opportunities and protection from predators (Ludsin et al 2010; also see Pangle et al 2012, Carreon-Martinez et al 2014. As a further contrast, larval walleye produced in the Detroit River are unlikely influenced by regional precipitation because river flows are sourced mainly from Lake Huron and remain stable under precipitation extremes (Pritt et al, unpublished manuscript).…”

“…First, recruitment variation of most ecologically and economically important fish populations, including walleye (Mion et al 1998, Roseman 2000 ), appears to be regulated by early life growth and survival. Second, the physical (e.g., wind-driven water circulation, upwelling; Hjort 1914, Lasker 1981, Iles and Sinclair 1982Hjort 1914, Cushing 1990, Carreon-Martinez et al 2014 processes that control early life growth and survival oftentimes are heterogeneous in both space and time (Houde 2008, 2009. In turn, the progeny of spawning stocks that are spatially and (or) temporally segregated would be expected to be strongly regulated by different (localized) processes, resulting in uncorrelated (i.e., asynchronous) recruitment.…”

High‐turbidity events in Western Lake Erie during ice‐free cycles: Contributions of river‐loaded vs. resuspended sediments

“…River plumes are driven by river discharge, wind, and the Earth's rotation collectively (Xia et al 2011;Jiang and Xia 2016). As the riverloaded sediments carry nutrients and contaminants from their watersheds, the generated plumes influence the heterogeneity in biological productivity and species interactions/migrations (Grimes and Kingsford 1996;Carreon-Martinez et al 2014;Xia et al 2016;Wu et al 2017). Resuspension is initiated by the combined effects of currents, surface-gravity waves, and high-frequency linear internal waves, among which the surface-gravity waves predominate in shallow lakes and coastal zones (Hawley and Eadie 2007;Green and Coco 2014;Valipour et al 2017).…”

Rainbow Darter (Etheostoma caeruleum, Storer, 1845) predation on early ontogenetic stages of Lake Sturgeon (Acipenser fulvescens, Rafinesque, 1817)

“…Direct (i.e., lethal) effects of predation can influence prey species population demographics by increasing mortality rates and/or decreasing reproductive success (Bailey & Houde, 1989;Crossman et al, 2017;Leggett & DeBlois, 1994;Waraniak, Blumstein, & Scribner, 2017). Predation efficiency is influenced by factors including habitat (Carreon-Martinez, Wellband, Johnson, Ludsin, & Heath, 2014;Denno, Finke, & Langellotto, 2005;Gadomski & Parsley, 2005) and predator physiological or phenotypic limitations, such as gape-limitation (Mittelbach, 1981;Rakocinski, 1991;Truemper & Lauer, 2005).…”