Temporal and spatial variability in stable isotope ratios of SPM link to local hydrography and longer term SPM averages suggest heavy dependence of mussels on nearshore production

Hill, J.M. and McQuaid, C.D. and Kaehler, S. (2008) Temporal and spatial variability in stable isotope ratios of SPM link to local hydrography and longer term SPM averages suggest heavy dependence of mussels on nearshore production. Marine biology, 154 (5). pp. 899-909. ISSN 0025-3162

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Official URL: http://dx.doi.org/10.1007/s00227-008-0983-2

Abstract

Temporal changes in hydrography affect suspended particulate matter (SPM) composition and distribution in coastal systems, potentially influencing the diets of suspension feeders. Temporal variation in SPM and in the diet of the mussel Perna perna, were investigated using stable isotope analysis. The δ13C and δ15 N ratios of SPM, mussels and macroalgae were determined monthly, with SPM samples collected along a 10 km onshore–offshore transect, over 14 months at Kenton-on-Sea, on the south coast of South Africa. Clear nearshore (0 km) to offshore (10 km) carbon depletion gradients were seen in SPM during all months and extended for 50 km offshore on one occasion. Carbon enrichment of coastal SPM in winter (June–August 2004 and May 2005) indicated temporal changes in the nearshore detrital pool, presumably reflecting changes in macroalgal detritus, linked to local changes in coastal hydrography and algal seasonality. Nitrogen patterns were less clear, with SPM enrichment seen between July and October 2004 from 0 to 10 km. Nearshore SPM demonstrated cyclical patterns in carbon over 24-h periods that correlated closely with tidal cycles and mussel carbon signatures, sampled monthly, demonstrated fluctuations that could not be correlated to seasonal or monthly changes in SPM. Macroalgae showed extreme variability in isotopic signatures, with no discernable patterns. IsoSource mixing models indicated over 50% reliance of mussel tissue on nearshore carbon, highlighting the importance of nearshore SPM in mussel diet. Overall, carbon variation in SPM at both large and small temporal scales can be related to hydrographic processes, but is masked in mussels by long-term isotope integration.

Item Type:Article
Additional Information:The original publication is available at www.springerlink.com
Uncontrolled Keywords:coastal ecosystems; suspended particulate matter; SPM; hydrography; change; Perna perna; diet; variability; temporal; spatial; stable isotope analysis; South Africa Eastern Cape; Kenton-on-Sea
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Science > Zoology & Entomology
ID Code:1017
Deposited By: Mrs Eileen Shepherd
Deposited On:23 Jun 2008
Last Modified:06 Jan 2012 16:19
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