Flocs, flows, and mechanisms decoupling larval supply from settlement
Zimmer, Cheryl Ann
Starczak, Victoria R.
Zimmer, Richard K.
MetadataShow full item record
Larval supply, settlement (24 h), and recruitment were measured simultaneously with flow and flocculated particulates (flocs) in a muddy, coastal embayment. Fortuitous observations indicated that flocs drifting above the bed touched down at slack tide. Unexpectedly, results showed that larval supply did not portend settlement for the two most abundant polychaetes, Mediomastus ambiseta (resident mud dweller) and Sabellaria vulgaris (nonresident sand dweller). Both variables fluctuated widely and were decoupled. Colonization of mud vs. sand trays was not significantly different, also due to high variances. A statistical power analysis indicated that resolving selectivity would require 45 (median) paired, replicate treatments. Time series of near-bed planktonic larvae showed sizeable and sporadic spikes. Even 24-h means failed to predict settlement. Sabellaria was numerous in zooplankton pump collections, rare in trays, and nonexistent in ambient sediments. In contrast, Mediomastus was absent from pump samples, but dominated mud trays and bottom cores. Floc contents, however, lend insight into these distributions. Densities (of order 105 m-3) of Sabellaria and Mediomastus in flocs greatly exceeded those in tray and pump samples (of order 103 m-3). Located between the water column and seafloor, organic-rich flocs may offer transient larvae food, shelter, transport, and perusal of settlement sites. When aggregates touch down, entrained Mediomastus might exit upon contact with suitable ambient sediments, whereas nonresident Sabellaria remain suspended. Flocs may thus play a critical role in shaping connectivity and structuring species distributions.
Author Posting. © Association for the Sciences of Limnology and Oceanography, 2012. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 57 (2012): 936-944, doi:10.4319/lo.2012.57.4.0936.
Suggested CitationLimnology and Oceanography 57 (2012): 936-944
Showing items related by title, author, creator and subject.
Zimmer, Cheryl Ann; Starczak, Victoria R.; Arch, Victoria S.; Zimmer, Richard K. (Sears Foundation for Marine Research, 2008-03)Planktonic larval settlement can be a major determinant of population and community dynamics. Settlement templates of benthic invertebrates have been attributed to biological, chemical, and hydrodynamic mechanisms. Completely ...
Zimmer, Walter M. X.; Tyack, Peter L.; Johnson, Mark P.; Madsen, Peter T. (Acoustical Society of America, 2005-03)The three-dimensional beam pattern of a sperm whale (Physeter macrocephalus) tagged in the Ligurian Sea was derived using data on regular clicks from the tag and from hydrophones towed behind a ship circling the tagged ...
Zimmer, Walter M. X.; Johnson, Mark P.; Madsen, Peter T.; Tyack, Peter L. (Acoustical Society of America, 2005-06)Strandings of beaked whales of the genera Ziphius and Mesoplodon have been reported to occur in conjunction with naval sonar use. Detection of the sounds from these elusive whales could reduce the risk of exposure, but ...