Behavior of prey links midwater and demersal piscivorous reef fishes

Abstract

Pelagic and demersal guilds of piscivorous fishes are linked by a variety of biological and physical processes that mediate interactions with common prey species. Understanding the behaviors of predators and prey can provide insight into the conditions that make such linkages possible. Here we report on the behaviors of mid-water piscivorous fishes and the responses of prey that produce feeding opportunities for demersal piscivorous fishes associated with "live bottom" ledge habitats off the coast of Georgia (northwest Atlantic Ocean). Prey taxa reduced nearest neighbor distances and retreated towards the seafloor during predatory attacks by mid-water fishes. Demersal fishes subsequently attacked and consumed prey in these ephemeral high density patches. No predation by demersal fishes was observed when prey species were at background densities. If the predator-prey interactions of demersal piscivorous fishes are commonly mediated by the predatory behavior of midwater piscivorous fishes and their prey, such indirect facilitative behaviors may be important in terms of the population processes (e.g., prey consumption and growth rates) of these demersal fishes.As guildas de peixes piscívoros pelágicos são conectadas às de peixes piscívoros demersais através de diversos processos biológicos e físicos que permeiam as interações com suas presas em comum. O conhecimento do comportamento de predadores e presas pode fornecer idéias a respeito das condições que tornam estes elos possíveis. Relatamos aqui os comportamentos de peixes piscívoros de meia-água e as respostas de suas presas que fornecem, assim, oportunidades alimentares para os peixes piscívoros demersais que vivem associados a fundos rochosos ao largo da costa da Geórgia (Oceano Atlântico). As presas reduziram a distância mínima entre os indivíduos e recolheram-se em direção ao fundo durante os ataques dos peixes de meia-água. Em seguida, peixes demersais atacaram e consumiram as presas destes agrupamentos efêmeros com alta densidade de indivíduos. Não foi observada predação por peixes demersais quando as presas estavam em densidades menores às causadas por ataques de peixes de meia-água. Caso as interações entre presas e peixes piscívoros demersais sejam comumente mediadas pelo comportamento predatório de peixes piscívoros de meia-água e suas presas, estes comportamentos facilitadores indiretos podem ser importantes em termos de processos populacionais (e.g., consumo de presas e taxas de crescimento) para certas espécies de peixes demersais.

Use of High-Resolution DIDSON Sonar to Quantify Attributes of Predation at Ecologically Relevant Space and Time Scales

“…Such a time period, while long by traditional visual sampling approaches, covers normal day (or night) periods inclusive of crepuscular periods over much of the globe and can capture variability at particular sample sites. The metrics derived from DIDSON imaging support, in general, diver observations related to the range in numbers and sizes of predators, coordinated group behaviors, and patchy prey distribution localized to ledge features (Auster et al, 2009(Auster et al, , 2013.…”

“…Demersal piscivores include black sea bass Centropristis striata, bank sea bass Centropristis ocyurus, scamp Mycteroperca phenax and gag grouper Mycteroperca microlepis. Both groups prey upon highly abundant round scad Decapterus punctatus, mackerel scad Decapterus macarellus, and juvenile tomtate Haemulon aurolineatum (Auster et al, 2009(Auster et al, , 2013.…”

“…Earlier work based on direct observation by divers (Auster et al, 2009) used discrete predation events as sample units and this approach is continued here for analysis. Small and large fish were present and moving within and through the ensonified volume in most records; however, this by itself does not indicate predation related behaviors.…”

“…A shortage of prey refugia has also been shown to cause short-term density dependent mortality due to predation (Johnson, 2006). If prey use particular seafloor features for refuge, predators may then occur at a higher density around these features (Kracker et al, 2008;Auster et al, 2009Auster et al, , 2011Auster et al, , 2013. Cosner et al (1999) suggests that predation rates are therefore density dependent for both predator and prey as competition between predators increases.…”

Facilitative behavioral interactions between deepwater piscivores at Isla del Coco National Park and Las Gemelas Seamount, Costa Rica

“…Studies by Auster & Lindholm (2002;2008) and Auster, Semmens, & Barber (2005, unpublished data) from tropical coral reefs in the Caribbean Sea, Indian Ocean, Coral Sea, and Gulf of California demonstrate that 40-68 % of non-cryptic reef fishes across feeding guilds exhibit some form of multi-species group foraging, indicating that group foraging is a common behavior in reef fish communities. The piscivore guild at sub-tropical "live-bottom" reefs off the southeast coast of the United States and in the eastern Gulf of Mexico have similar patterns and exhibit a complex web of facilitative behaviors that enhance prey capture (Auster, Godfrey, Watson, Paquette, & McFall, 2009;Auster et al, 2011;2013b). For example, 72 % of predation events at reefs off the southeast United States involved interactions in which mixed-species groups cooperatively searched for, stalked and attacked common prey species (Auster et al, 2013b).…”