A field test of the effects of megafaunal burrows on benthic chamber measurements of sediment-water solute fluxes

Abstract

A field test of the effects of megafaunal burrows on benthic chamber measurements of sediment-water solute fluxes 'Centre for Coastal and Marine Sciences, Dunstaffnage Marine Laboratory. PO Box 3, Oban, Argyll PA34 4AD, Scotland, UK 'University Marine Biological Station, Millport, Isle of Cumbrae KA28 OEG. Scotland. UK ABSTRACT: Benthic chambers are widely used in biogeochemical studies of marine sediments, but it is not known whether sediment-water solute fluxes recorded using such apparatus will be affected by the presence of a megafaunal burrow opening in the enclosed area of sea floor. We investigated this question in a shallow sea loch using simple benthic chambers deployed by divers over 2 contrasting burrow types, those of the mud-shrimp Callianassa subterranea and of the echiuran worm Maxmuelleria lankesteri. Fluxes of dissolved oxygen, manganese (11) and nutrients were measured over an 18 to 25 h incubation period and compared with those recorded over nearby sediment lacking megafaunal burrow openings. Chambers enclosing C. subterranea burrows recorded a significantly higher efflux of phosphate than controls, and efflux of ammonium was also consistently (though non-signdicantly) greater over burrows. C. subterranea burrows had no detectable effect on any other measured flux. Chambers enclosing M. lankesten burrow openings dffered from controls only in showing a significantly higher efflux of nitrate. This nitrate effect was particularly marked over M. lankesten ejecta mounds, suggesting that these features may be localized sites of enhanced nitrification. Ranges of variation were high for all measured parameters, indicating that at this site, data from a single chamber incubation would be unlikely to unambiguously signify the presence of an identifiable megafaunal burrow opening. Spatial heterogeneity in solute flux rates illustrates the need to maximize replication in field studies using benthic chambers.

Disturbance to Marine Benthic Habitats by Trawling and Dredging: Implications for Marine Biodiversity

“…Interactions between bioturbation and mineralization processes in sediments are highly nonlinear and are characterized by the presence of strong feedback loops between deposit feeders, their food, and their chemical environment (Herman et al 1999). Variation in large burrow structures and animal activity can result in markedly different biogeochemical fluxes, in terms of both rates and chemicals (Hughes et al 2000). As well as influencing water column production, bioturbation can also affect the growth of benthic species that use this resource (Weinberg & Whitlatch 1983).…”

Habitat and Ecology of Nephrops norvegicus

“…Further complexity is added by the non-additive effects of different species on flux rates (Michaud et al, 2009), making it difficult to predict flux rates on the basis of parameters estimated for single species. Considerable replication in space and time may be needed to generate a full description of benthic fluxes in areas where burrows are present (Hughes et al, 2000). Considerable replication in space and time may be needed to generate a full description of benthic fluxes in areas where burrows are present (Hughes et al, 2000).…”

An approach to developing nutrient criteria for Pacific Northwest estuaries : a case study of Yaquina Estuary, Oregon /

“…Francisco, however the reported benthic flux data in four of the studies (i.e., Dollar et al 1991;Garber et al 1992;Thom et al, 1994;Lamed, 2003) may not accurately estimate estuary-scale nutrient fluxes in Yaquina Estuary because they do not account for the presence of thalassinid burrowing shrimp. The presence of burrowing shrimp can result in the water inside of the benthic flux chamber being exchanged with water outside of the chamber via shrimp burrows (e.g., Hughes et al, 2000), which violates the requirement that benthic chambers be closed microcosms (Forja and Gomez-Parra, 1998).…”

“…Failure to take the presence of burrowing shrimp into account can result in water inside the chamber being exchanged with water outside of the chamber via shrimp burrows (e.g., Hughes et al 2000), which violates the requirement that benthic chambers be closed microcosms (Hofman andde Jong, 1993, Forja andGomez-Parra 1998). In the case of one study, benthic chamber treatments deliberately excluded shrimp (Thom et al, 1994), and while these measurements would represent tide flat habitats that have no shrimp, such areas are only 16% of the total Yaquina tide flat area .…”