Turbidity interferes with foraging success of visual but not chemosensory predators

Abstract

Predation can significantly affect prey populations and communities, but predator effects can be attenuated when abiotic conditions interfere with foraging activities. In estuarine communities, turbidity can affect species richness and abundance and is changing in many areas because of coastal development. Many fish species are less efficient foragers in turbid waters, and previous research revealed that in elevated turbidity, fish are less abundant whereas crabs and shrimp are more abundant. We hypothesized that turbidity altered predatory interactions in estuaries by interfering with visually-foraging predators and prey but not with organisms relying on chemoreception. We measured the effects of turbidity on the predation rates of two model predators: a visual predator (pinfish, Lagodon rhomboides) and a chemosensory predator (blue crabs, Callinectes sapidus) in clear and turbid water (0 and ∼100 nephelometric turbidity units). Feeding assays were conducted with two prey items, mud crabs (Panopeus spp.) that rely heavily on chemoreception to detect predators, and brown shrimp (Farfantepenaus aztecus) that use both chemical and visual cues for predator detection. Because turbidity reduced pinfish foraging on both mud crabs and shrimp, the changes in predation rates are likely driven by turbidity attenuating fish foraging ability and not by affecting prey vulnerability to fish consumers. Blue crab foraging was unaffected by turbidity, and blue crabs were able to successfully consume nearly all mud crab and shrimp prey. Turbidity can influence predator–prey interactions by reducing the feeding efficiency of visual predators, providing a competitive advantage to chemosensory predators, and altering top-down control in food webs.

Effects of crayfish density, body size and substrate on consumption of lake sturgeon (Acipenser fulvescens Rafinesque, 1817) eggs by invasive rusty crayfish [(Orconectes rusticus (Girard, 1852)]

“…For example, our experimental tanks had relatively low flow rates compared to the specific areas of natural streams where lake sturgeon spawn. However, while increasing stream water velocity and the associated increase in water turbidity that tends to reduce predation rates of visual aquatic predators (Ward, Morton‐starner, & Vaage, ), the same is not always true for chemosensory predators like crayfish (Lunt & Smee, ). Clark, Kershner, and Montemarano () also showed that the distribution and density of crayfish within stream channels were often size dependent, with larger individuals found in the deep pools with large substrate.…”

Effects of Turbidity on Prey Selection and Foraging Rate of Hatchery‐Reared Juvenile Tiger Muskellunge

“…Water clarity, particularly turbidity, affects interactions between predator and prey in aquatic environments and also influences interactions between and within species, thereby shaping fish communities (Carter et al. ; Lunt and Smee ; Figueiredo et al. ).…”

Altered visual environment affects a tropical freshwater fish assemblage through impacts on predator–prey interactions

“…Since turbidity is primarily a visual stressor in aquatic systems, predators that are more reliant on visual cues for prey detection should be more affected by increasing turbidity (Rowe & Dean 1998;Lunt & Smee 2015). Since turbidity is primarily a visual stressor in aquatic systems, predators that are more reliant on visual cues for prey detection should be more affected by increasing turbidity (Rowe & Dean 1998;Lunt & Smee 2015).…”

“…Indeed, turbidity often acts as a refuge for prey when predators rely heavily on vision for prey detection and capture (Gregory & Levings 1998;Lehtiniemi et al 2005). demographic patterns) effects of turbidity on predators should depend in part on how much a given predator relies on visual cues to detect and capture prey, and this reliance can differ between coexisting predators (Rowe & Dean 1998;Lunt & Smee 2015). increasing turbidity).…”