Predation mortality of bay anchovy Anchoa mitchilli eggs and larvae due to scyphomedusae and ctenophores in Chesapeake Bay

Abstract

We measured predation on bay anchovy Anchoa mitchilli eggs and larvae by abundant scyphomedusae Chrysaora quinquecirrha and ctenophores Mnemiopsis leidyi from gut contents, digestion rates, and densities of predators and prey during 9 d in July 1991 at 4 stations in Chesapeake Bay, USA. These predation rates were compared to egg and larval mortality rates measured concurrently in ichthyoplankton surveys. Daily predation by medusae and ctenophores was 19 * 13":) (mean + SD) of the eggs over the 20 h stage duration, with medusae responsible for 26 to 100% of the predation. These gelatinous predators accounted for 21 i 17 ":, of the total estimated daily egg-stage rnortality. On average, medusae consumed 29 + 14 O/u d -' of the larval bay anchovy, which was 41 35% of total estimated larval mortality. Predation on larvae by ctenophores was not detected. These predation effects are compared with those measured concurrently in free-drifting 3 2 m3 mesocosms. We conclude that medusae, which had high feeding rates but low abundances, and ctenophores, which had lour feeding rates but high abundances, were important predators of bay anchovy eggs and larvae in the mesohaline region of Chesapeake Bay

Predation by the scyphomedusan Chrysaora quinquecirrha on Mnemiopsis leidyi ctenophores

“…Similarly, clearance rates by medusae 240 mm in 3.2 m3 mesocosms were about twice those in 1 m3 tanks ( Table 3). Reduction of feeding by gelatinous zooplankton in containers has been shown repeatedly (e.g summarized for scyphomedusae in Purcell et al 1994a). In addition to container effects, some of the clearance rates in both studies were measured at high prey densities (5 to 10 m-3) and may be low due to saturation of feeding ( Fig.…”

“…Clearance rates and growth rates of ephyrae when fed larval ctenophores were greater than when fed ciliates, rotifers, or copepod nauplii (Olesen et al unpubl.). Consumption of zooplankton and ichthyoplankton in July 1991 (Purcell et al 1994a) would meet daily nitrogen demands (5 400 pg N d-') for medusae 160 mm diameter (Purcell 1992). However, just 1 ctenophore 23.8 mm in length (3.5 m1 volume) contains 400 1-19 nitrogen (calculated from equations in Nemazie et al 1993).…”

Effects of low dissolved oxygen on zooplankton predation by the ctenophore Mnemiopsis leidyi

“…Mnemiopsis leidyi is an important predator of zooplankton and ichthyoplankton in Chesapeake Bay and its tributaries (Cowan & Houde 1992, 1993, Purcell et al 1994a,b, 2001b, Purcell & Decker 2005. M. leidyi is a cruising predator that captures prey within their outstretched lobes and tentillae (Waggett & Costello 1999).…”

Proceedings of the Smithsonian Marine Science Symposium

“…(Current addresses: E. Graham (Cowan et al, 1992;Cowan and Houde, 1993;Purcell et al, 1994;Purcell and Decker, 2005). In mesohaline portions of the Chesapeake Bay system, the major predator of M. leidyi, the scyphomedusa Chrysaora quinquecirrha, usually becomes abundant in early July and persists through the end of summer (Cargo and King, 1990).…”

“…In late spring and early summer, M. leidyi can be abundant in Chesapeake Bay and its tributaries, where it is a dominant consumer, potentially capable of clearing much of the daily standing stock of zooplankton and ichthyoplankton Eileen S. Graham, Danielle M. Tuzzolino, Rebecca B. Burrell, and Denise L. Breitburg, Smith- (Cowan et al, 1992;Cowan and Houde, 1993;Purcell et al, 1994;Purcell and Decker, 2005). In mesohaline portions of the Chesapeake Bay system, the major predator of M. leidyi, the scyphomedusa Chrysaora quinquecirrha, usually becomes abundant in early July and persists through the end of summer (Cargo and King, 1990).…”