Measuring sedimentation rates may provide useful information on the habitat preferences of marine organisms. To understand the effect of flow rates and meteorological conditions on sedimentation in the absence of other confounding factors, sedimentation of organic (OM) and inorganic (IOM) matters was measured at 6 sites in Lough Hyne Marine Reserve (a semienclosed marine lake) over the course of 13 months. During winter, both OM and IOM were imported to the Lough, peaking in December at Whirlpool, the site nearest to the Lough entrance, likely as a result of extreme weather conditions causing resuspension of matter outside the Lough. Highest inorganic matter (IOM) sedimentation occurred in December (47.36？gm？2d？1 at Whirlpool Cliff) and was related to November wind speeds ( , ). Decreasing current speed also caused a decline in IOM sedimentation. Highest OM sedimentation occurred in December at Whirlpool (5.59？gm？2d？1), but was not related to meteorological conditions. No single environmental factor strongly influenced organic matter (OM) sedimentation. One-way ANOVAs on OM and log-transformed IOM data showed that sedimentation differed significantly amongst the six sites within the Lough. Increased plankton production in the Lough during summer led to increased OM sedimentation in areas of low current speed away from the entrance of the Lough. 1. Introduction The settlement of matter out of the water column onto the seafloor is an important process for benthic fauna. Sinking organic matter provides a high-quality food source for marine benthic communities which, except where light can still penetrate and benthic photosynthesis occur, are dependent on surface water production for energy input [1]. Sedimentation rates are largely influenced by the availability of nutrients in the surface water and by seasonality, which influences plankton growth. Dying phytoplankton blooms provide massive sedimentation events in short periods with a marked seasonality [2], at least at medium and high latitudes. However, benthic communities can be adversely affected by high organic matter input as described by classic models [3]: an increase of organic materials at first causes an increase in benthic biomass and microbial metabolism, but eventually this leads to the complete depletion of oxygen. The consequences of anoxia in the benthic habitat and the overlying water column are massive die-off events in the benthic community [4]. Additionally, areas of low water exchange, such as semi-enclosed bays and fjords, are known to develop temporal or permanent stratification of
References
[1]
P. A. Quijón, M. C. Kelly, and P. V. R. Snelgrove, “The role of sinking phytodetritus in structuring shallow-water benthic communities,” Journal of Experimental Marine Biology and Ecology, vol. 366, no. 1-2, pp. 134–145, 2008.
[2]
U. Riebesell, “Comparison of sinking and sedimentation rate measurements in a diatom winter/spring bloom,” Marine Ecology Progress Series, vol. 54, pp. 109–119, 1989.
[3]
T. Pearson and R. Rosenberg, “Macrobenthic succession in relation to organic enrichment and pollution of the marine environment,” Oceanography Marine Biology Annual Revue, vol. 16, pp. 229–311, 1978.
[4]
C. Heip, “Eutrophication and zoobenthos dynamics,” Ophelia, vol. 41, pp. 113–136, 1995.
[5]
R. J. Diaz and R. Rosenberg, “Marine benthic hypoxia: a review of its ecological effects and the behavioural responses of benthic macrofauna,” Oceanography and Marine Biology, vol. 33, pp. 245–303, 1995.
[6]
J. S. Gray and M. Elliott, Ecology of Marine Sediments, from Science to Management, Oxford University Press, Oxford, UK, 2009.
[7]
R. Bassindale, F. J. Ebling, J. A. Kitching, and R. D. Purchon, “The ecology of the lough ine rapids with special reference to water currents,” Journal of Ecology, vol. 36, pp. 305–322.
[8]
R. McAllen, J. Davenport, K. Bredendieck, and D. Dunne, “Seasonal structuring of a benthic community exposed to regular hypoxic events,” Journal of Experimental Marine Biology and Ecology, vol. 368, no. 1, pp. 67–74, 2009.
[9]
R. Bassindale, E. Davenport, F. J. Ebling, J. A. Kitching, M. A. Sleigh, and J. F. Sloane, “The ecology of the lough ine rapids with special reference to water currents. VI. Effects of the rapids on the hydrography of the South Basin,” Journal of Ecology, vol. 45, pp. 879–900, 1957.
[10]
M. Jessopp, R. McAllen, J. O. O’Halloran, and T. Kelly, “Nutrient and Ecosystem Dynamics in Ireland’s only marine nature reserve (NEIDIN),” STRIVE Report 66, Environmental Protection Agency, 2011.
[11]
K. A. Rawlinson, J. Davenport, and D. K. A. Barnes, “Temporal variation in diversity and community structure of a semi-isolated neuston community,” Biology and Environment, vol. 105, no. 2, pp. 107–122, 2005.
[12]
J. J. Bell and D. K. A. Barnes, “The relationship between sedimentation, flow rates, depth and time at Lough Hyne Marine Reserve,” Irish Naturalist Journal, vol. 27, pp. 106–116, 2002.
[13]
L. H？kanson, S. Floderus, and M. Wallin, “Sediment trap assemblages–a methodological description,” Hydrobiologia, vol. 176-177, no. 1, pp. 481–490, 1989.
[14]
S. G. Wakeham, J. I. Hedges, C. Lee, and T. K. Pease, “Effects of poisons and preservatives on the composition of organic matter in a sediment trap experiment,” Journal of Marine Research, vol. 51, no. 3, pp. 669–696, 1993.
[15]
J. Davenport, T. V. Moloney, and J. Kelly, “Common sea anemones Actinia equina are predominantly sessile intertidal scavengers,” Marine Ecology Progress Series, vol. 430, pp. 147–155, 2011.
[16]
V. Smetacek, K. von Br？ckel, B. Zeitzschel, and W. Zenk, “Sedimentation of particulate matter during a phytoplankton spring bloom in relation to the hydrographical regime,” Marine Biology, vol. 47, no. 3, pp. 211–226, 1978.
[17]
V. Smetacek, “Annual cycle of sedimentation in relation to plankton ecology in western Kiel Bight,” Ophelia, Marine Biological Laboratory Supplement, vol. 1, pp. 65–76, 1980.
[18]
K. A. Rawlinson, J. Davenport, and D. K. A. Barnes, “Tidal exchange of zooplankton between Lough Hyne and the adjacent coast,” Estuarine, Coastal and Shelf Science, vol. 62, no. 1-2, pp. 205–215, 2005.
[19]
M. J. Jessopp and R. J. McAllen, “Go with the flow: tidal import and export of larvae from semi-enclosed bays,” Hydrobiologia, vol. 606, no. 1, pp. 81–92, 2008.
[20]
M. P. Johnson and M. J. Costello, “Local and external components of the summertime plankton community in Lough Hyne, Ireland a stratified marine inlet,” Journal of Plankton Research, vol. 24, no. 12, pp. 1305–1315, 2002.
