Density Dependence in Suspension-Feeding and Deposit-Feeding Populations of the Bivalve Macoma balthica: A Field Experiment

10.2307/4735 ◽  
1986 ◽  
Vol 55 (2) ◽  
pp. 517 ◽  
Author(s):  
E. B. Olafsson
Keyword(s):  
Field Experiment ◽  
Density Dependence ◽  
Macoma Balthica ◽  
Suspension Feeding ◽  
Deposit Feeding

Effects of the deposit-feeding benthic bivalve Macoma balthica on meiobenthos

Oecologia ◽  
1993 ◽  
Vol 93 (4) ◽  
pp. 457-462 ◽  
Author(s):  
Emil Olafsson ◽  
Ragnar Elmgren ◽  
Ourania Papakosta
Keyword(s):  
Macoma Balthica ◽  
Deposit Feeding

Ultrastructure of the podia of Amphiura chiajei and Amphiura filiformis and their role in feeding

2006 ◽  
Vol 86 (4) ◽  
pp. 817-822 ◽  
Author(s):  
John K. Keogh ◽  
Brendan F. Keegan
Keyword(s):  
Chemical Composition ◽  
Morphological Study ◽  
Secretory Cells ◽  
Suspension Feeding ◽  
Head Region ◽  
Feeding Styles ◽  
Amphiura Filiformis ◽  
The Difference ◽  
Mucus Cells ◽  
Deposit Feeding

Morphological study of the podia of the suspension feeding Amphiura filiformis and the deposit feeding Amphiura chiajei revealed sensory–secretory complexes in the podial epidermis, consisting of four cells, two secretory and two sensory. Large mucus cells were found in association, but not exclusively, with the sensory–secretory complexes. In A. filiformis, mucus cells stained positively for both acid and neutral mucopolysaccharides, while, in A. chiajei, these cells stained only for acid mucopolysaccharides. The surfaces of the arm podia in A. chiajei were relatively smooth, while the arm podia of A. filiformis bear papillae. The sensory–secretory complexes open through numerous paired pores, with each pair having an intervening cilium. Pores were restricted to the podial tip in A. chiajei, while in A. filiformis they are concentrated on the podial tip and on the papillae. Amphiura chiajei shows very little differentiation of the podia along the length of the arm. In A. filiformis, the distal podia have papillae throughout their entire length, with pores being found on the head region and the papillar tips. Here, the papillae are oriented in such a way (i.e. facing inward towards the ventral arm plate) as to increase the area of the filtering surface of the podium, serviced by the sticky secretions from the sensory–secretory complexes. The proximal podia are relatively simple in structure and are thought to function more in the transportation of mucus wrapped particles to the mouth rather than in their capture. The difference in structure of the podia and chemical composition of podial secretory cells are taken to reflect the difference in feeding styles of the two species.

Ecotoxicity of contaminated sediments, a matter of bioavailability

1998 ◽  
Vol 37 (6-7) ◽  
pp. 225-231 ◽  
Author(s):  
N. H. B. M. Kaag ◽  
E. M. Foekema ◽  
M. C. Th. Scholten
Keyword(s):  
Dreissena Polymorpha ◽  
Sea Water ◽  
Feeding Habits ◽  
Macoma Balthica ◽  
Contaminated Sediments ◽  
Suspension Feeding ◽  
Simple Relationship ◽  
Filter Feeder ◽  
Arenicola Marina ◽  
The Baltic

Marine and freshwater mesocosm-scale experiments with contaminated sediments have shown that there is a direct relationship between the accumulated contaminant levels and the feeding habits of the organisms used. The highest levels of PAHs and PCBs were found in the sediment feeding lugworm Arenicola marina and in Tubifex worms. The levels of contaminants in the suspension feeding mussels Mytilus edulis and the zebra mussels, Dreissena polymorpha, were not influenced by the contaminant content of the sediments, but were related instead to the level of contaminants in the sea water above. Intermediate levels were found in the baltic tellin, Macoma balthica, which is a filter feeder as well as a deposit feeder, depending on the availability of food. These results show that there is no simple relationship between contaminant concentration in the sediments and bioavailability. Higher levels of contaminants do not necessarily lead to higher levels of these contaminants in Arenicola, due to differences in the sediment structure and the ageing of the contamination. On the other hand, toxic effects are related to the internal concentrations of certain chemicals. The internal concentrations observed in Arenicola may provide a good estimation of the true bioavailability of sedimentary contaminants and can also be used as an indicator for potential environmental effects.

Predation, Density Dependence, and Life Histories of Dragonflies: A Field Experiment in a Freshwater Community

1995 ◽  
Vol 14 (4) ◽  
pp. 547-562 ◽  
Author(s):  
Dan M. Johnson ◽  
Thomas H. Martin ◽  
Mahendra Mahato ◽  
Larry B. Crowder ◽  
Philip H. Crowley
Keyword(s):  
Field Experiment ◽  
Density Dependence ◽  
Life Histories ◽  
Freshwater Community

scholarly journals Mussels drive polychlorinated biphenyl (PCB) biomagnification in a coastal food web

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kimberly D. Prince ◽  
Sinead M. Crotty ◽  
Alexa Cetta ◽  
Joseph J. Delfino ◽  
Todd M. Palmer ◽  
...  
Keyword(s):  
Field Experiment ◽  
Food Web ◽  
Trophic Interactions ◽  
Polychlorinated Biphenyl ◽  
Critical Role ◽  
Ecosystem Engineering ◽  
Sediment Contamination ◽  
Suspension Feeding ◽  
International Regulation ◽  
Cascading Effects

AbstractDespite international regulation, polychlorinated biphenyls (PCBs) are routinely detected at levels threatening human and environmental health. While previous research has emphasized trophic transfer as the principle pathway for PCB accumulation, our study reveals the critical role that non-trophic interactions can play in controlling PCB bioavailability and biomagnification. In a 5-month field experiment manipulating saltmarsh macro-invertebrates, we show that suspension-feeding mussels increase concentrations of total PCBs and toxic dioxin-like coplanars by 11- and 7.5-fold in sediment and 10.5- and 9-fold in cordgrass-grazing crabs relative to no-mussel controls, but do not affect PCB bioaccumulation in algae-grazing crabs. PCB homolog composition and corroborative dietary analyses demonstrate that mussels, as ecosystem engineers, amplify sediment contamination and PCB exposure for this burrowing marsh crab through non-trophic mechanisms. We conclude that these ecosystem engineering activities and other non-trophic interactions may have cascading effects on trophic biomagnification pathways, and therefore exert strong bottom-up control on PCB biomagnification up this coastal food web.

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