Response of a soft-bottom harpacticoid community to stingray (Dasyatis sabina) disturbance

262

182

A number of recent studies have shown that water-column processes exert an important influence on meiofaunal recruitment and colonization of new areas. T h~s paper reviews those studies which have investigated the water-column occurrence of meiofauna and the subsequent settlement process. Two distinct patterns exist for recruitment via water-column pathways: active entry of meiofauna into the water and passive erosion of meiofauna from the sediments. A conceptual model is proposed in which 4 factors interact to determine whether active vs passive mechanisms are most important for a given community: taxonomic con~position, hydrodynamics, aboveground structure, and disturbance. For the melofauna of areas which are hydrodynamically benign and dominated by actice swimmers (e. g, seagrass beds), water-column recruitment should involve substrate cholce through active swimming. In areas which are free of aboveground structure and more rigorous hydrodynamically (e. g. tidal flats, beaches) passive recruitment processes dominate and are modified by behaviors which may influence transport and settlement. In all habitats, structure probably acts to enhance active emergence to some extent while disturbance events may lead to increased suspension and possibly actlve emergence Future directions are discussed with an emphasis on the need for the development and standardization of new methodologies which can be used in a variety of habitats.

Section: Disturbancementioning

confidence: 99%

Dispersal of marine meiofauna. Areview and conceptual model explaining passive transport and active emergence with implications for recruitment

Palmer¹

1988

262

182

“…The activities of the macrofauna are a source of disturbance which may influence the structure of meiofaunal assemblages (Reise & Ax 1979, Thistle 1980, Reidenauer & Thistle 1981, Sherman et al 1983, Creed & Coull 1984, Hicks 1984, Warwick et al 1986, Palmer 1988, Warwick et al 1990, , , Sundelin & Elmgren 1991. However, there are few reports on experiments where the intensity of biological disturbance has been graded into O Inter-Research/Printed in Germany more than 2 categories, i.e.…”

Section: Introductionmentioning

confidence: 99%

Effects of biological disturbance by benthic amphipods Monoporeia affinis on meiobenthic community structure: a laboratory approach

Ólafsson¹,

Elmgren²

1991

In order to evaluate the importance of biological disturbance on meiofaunal communities in muddy habitats, a laboratory experiment was performed at the Asko Laboratory in the northwestern Baltic proper The benthic amphipod Monoporeia aff~nis (Lindstrom) was added to microcosms containing sublittoral mud, in quantities varying from zero up to 80 ind. 104cm-~ After 2 mo the density of nematodes, the most abundant meiofauna taxon (97 %), was greatest in microcosms without amphipods, but they also occurred in higher numbers in microcosms containing a high density of M.affinis, compared to low and medium density microcosms. M. affinis appears to have a negative effect on surface-dwelling nematode species but a positive effect on the deeper dwelling Daptonema sp.However, nematode assemblage structure remained very similar in all treatments. Copepod abundances increased with increas~ng numbers of amphipods (p <0.002) and were highest in the high density microcosms. In the microcosms without amphipods, Macoma balthica spat was almost twice as abundant as in the amphipod treatments. For kinorhynchs and turbellarians there were also significant differences between treatments. The different responses of the major taxa to the biological disturbance may reflect the multifactorial nature of biotic perturbations.

“…In finding that meiofaunal abundances on an artificially disturbed intertidal mudbank rapidly returned to ambient levels within the space of one tidal cycle (12 h), Sherman & Coull (1980) suggested that incoming recruits to the disturbed patch did so by either active mobility over the sediment surface, or passively via tidal transport in the water column. These 2 pathways have repeatedly been invoked as those of importance in the rapid reestablishment of meiofaunal densities in habitats either naturally disturbed or artificially manipulated (Bell & Sherman 1980, Thistle 1980, Hockin & Ollason 1981, Reidenauer & Thistle 1981, Bell & Coen 1982, Van Blaricom 1982, Alongi et al 1983, Chandler & Fleeger 1983, Sherman et al 1983, Ambrose 1986. Results from reports by Palmer (1984, and subsequently with co-workers), have added considerable weight to the passive erosional method of entry into the water column with subsequent transport and supposed recolonization of viable meiofaunal propagules.…”

Section: Distance Travelled By Rafts Fate Of Rafted Populationmentioning

confidence: 99%

Sediment rafting: a novel mechanism for the small-scale dispersal of intertidal estuarine meiofauna

Hicks¹

1988

ABSTRACT. Epontic diatoms from intertidal sandy sediments produce considerable quantities of extracellular mucopolysaccharides that are used for locomotion, adhesion to sediment particles and as antidesiccants. These mucoid exopolymers dry out during low tide and cement sandgrains together thus stabilizing the surficial deposit. Under benign microclimatic conditions in Pauatahanui Inlet, New Zealand, these mucoid films with bound surface sediments peel off the substratum and float onto the surface of incoming tidal waters. Large numbers of meiofaunal organisms are carried aboard these films which can subsequently be rafted considerable distances (10's of metres) at the whim of tidal currents and winds. Locally abundant epibenthic copepods are most prone to be passively conveyed in this way, and numbers on rafts are dependent on both microspatial and temporal factors that control population density at the site. Tiny naupliar stages of the harpacticoid Parastenhelia megarostrum dominate the rafted population, due to their intimate clinging association with surflcial particles. Survivorship is high in individuals that have undergone raftlng; rafts thus function as effective agents of dispersal for intertidal epibenthic meiofauna. Along with active migration by cra~vling and passive water column transport, this is the third significant pathway of small-scale within-locality dispersal for meiofauna to be revealed and investigated. It must be considered as a contributing mechanism of recruitment for meiofaunal organisms known to rapidly recolonlze disturbed or denuded habitat.