The role of nutrition in regulating the population dynamics of opportunistic, surface deposit feeders in a mesohaline community

Abstract

The role of food resources in regulating seasonal population dynamics was determined in a benthic community typical of mesohaline regions in Chesapeake Bay. Four macroinvettebrates dominated the community: the bivalve Mucoma balthicu, the polychaetes Streblospio benedicti and Nereis succinea. and the amphipod Leptocheirus plumulosus. Several factors seem to regulate population dynamics at different times of the year. In March, growth and reproduction rates accelerated as temperature and phytodetrital sedimentation increased. In April, invertebrate growth rates plateaued while estimated community N requirements were equivalent to estimated N availability. In May, invertebrate growth and reproduction rates rapidly declined while estimated community energy requirements were greater than sedimenting energy supplies. In June, larval recruitment was heavy for S. henedicti and L. plumulosus; however, these juveniles showed no iapparent growth during June and their densitiesrapidly declined. The sudden appearance and disappearance of these juveniles was solely responsible for the boom-and-bust dynamics of S. benedicti and L. plumulosus. Essential W3-polyunsaturated fatty acids and essential amino acids were present at high levels in spring but were present in only trace amounts during summer. Growth of juvenile S. benedicti and L. plumulosus recruits was most likely limited by food supply in June and July, especially by the availability of essential nutrients. Estimates of predation rates could not account for these population declines.

Variation in detrital enrichment causes spatio-temporal variation in soft-sediment assemblages

“…The combination of these factors creates an ideal environment for microbial productivity and population growth of deposit-feeding invertebrates when temperatures increase in March (Levinton 1985, Lopez & Levinton 1987. Nevertheless, these excess detrital resources usually run out in early summer and microbial production decreases, closely followed by crashes in populations of opportunistic deposit-feeders (Marsh & Tenore 1990, Cheng et al 1993. It is also possible that a seasonal increase in predation of annelids by fishes and crabs in late spring contributes to the demise and suppression of annelid abundances in some systems.…”

Review of the reproductive biology of amphipods and their endocrine regulation: Identification of mechanistic pathways for reproductive toxicants

“…animals with a continuous food supply containing omega-3 polyunsaturated fatty acids support high fecundity in the detritus-feeding amphipod Melita plumulosa [41]. On the contrary, seasonal limitation of essential omega-3 polyunsaturated fatty acids and essential amino acids can reduce the fecundity and population abundances of the deposit-feeding amphipods Leptocheirus plumulosus and Monoporeia affinis in the field [42,43]. Vitellogenesis in the amphipod O. gammarella, involves two phases, primary and secondary vitellogenesis [40].…”

Community structure and bioturbation potential of macrofauna at four North Sea stations with contrasting food supply

“…Changes in benthic community structure have been associated with biotic factors such as con~petition and predation (Rhoads & Young 1970, Weinberg 1984 and abiotic factors such as water depth (Hyland et al 1991), current velocity (Wildish & Peer 1983), sediment stability (Probert 1984), sedimentation rate (Schaffner et al 1987, Aller & Stupakoff 1996, oxygen concentration (Levin et al 1991), silt content (Eleftheriou & Basford 1989) and organic loading (Dauer & Conner 1980). In particular, the amount and the nutritional quality of the organic material in the sediment is believed to play a key role influencing the biomass (Grebmeier et al 1988), vertical distribution (Lin & Hines 1994) and trophic structure of rnacrofaunal communities (Marsh & Tenore 1990). On the other hand, macrofauna affects the distribution of organic matter in sediments by bioturbation (Wheatcroft 1990, Blair et al 1996.…”