Larval swimming and postlarval drifting behavior in the infaunal bivalve Sinonovacula constricta

We compared spatial variation in the abundance of I n g George whiting Sillaginodes punctata post-larvae in the southern part of Port Phillip Bay, Australia, with predictions of hydrodynamic and dispersal numerical models that included passive transport, and vertical migratory behaviour previously observed in the field. Post-larvae were sampled at 20 sites on cruises in the spring of 1994 and 1995. Modelling included a 'passive' case with particles mixed through the water column, 'active' behaviour mirroring die1 and tidal variation in the field, and 'day/night' behaviour where behaviour in the field was averaged across tides. Correlations between model simulations and post-larval distribution were highest in 1995 and were similar amongst the 3 simulations (58% of variation explained for both the passive and dayhight cases). In 1994, variation in the spatial distribution explained was highest for the passive case, intermediate for the active case and lowest for the day/night case. Prevailing winds were quite different between years, with westerlies prevailing in 1994 but significant periods of easterly winds in 1995. These differences were reflected by particle cllstributions from simulation~ including behaviour, but were not reflected in post-larval distributions. A negative correlation was found between post-larval abundances and distance from shore. When model predictions and distance from shore were combined in a multiple regression, approximately 70% of the spatial variation in post-larval abundance was explained in 1995. The results imply that although the passive transport model was an excellent predictor of post-larval abundance in both years, observed vertical migration was not influencing transport, and post-larvae were closer to shore than expected, possibly due to behaviours other than vertical migration. The close association of S. punctata post-larvae with the coastline provided a mechanism for transport further into the bay, against the prevailing wind field.

Section: Discussionmentioning

confidence: 99%

The role of passive transport and the influence of vertical migration on the pre-settlement distribution of a temperate, demersal fish:numerical model predictions compared with field sampling

Jenkins¹,

Black²,

Keough³

1999

“…Resuspension of post-larvae and juveniles can initiate post-settlement transport (Rijnsdorp et al 1985, Wang & Xu 1997, Etherington & Eggleston 2000, Blackmon & Eggleston 2001. have suggested Sillaginodes punctata post-larvae settling in seagrass beds near the entrance to Port Phillip Bay could be resuspended during increased physical disturbance, thus initiating secondary planktonic dispersal.…”

Section: Discussionmentioning

confidence: 99%

Role of physical disturbance in structuring fish assemblages in seagrass beds in Port Phillip Bay, Australia

Moran¹,

Jenkins²,

Keough³

et al. 2003

Disturbance in seagrass habitats may cause variation in the structure of fish assemblages and individual taxa. One important form of disturbance is wave action associated with strong winds. Total fish abundance and species richness from seagrass beds at 2 sites in Port Phillip Bay, Australia, were sampled during low and high wave disturbance. During high wave action (> 0.25 m) in seagrass beds, abundance of fish at one site decreased significantly, but species richness was unaffected at both sites. Plankton sampling conducted at the same time as seagrass sampling (directly 300 m offshore from the seagrass sites) found that species richness significantly increased during high wave conditions at both sites. Total fish abundance similarly increased in the plankton during high wave conditions at one site. We conclude that variation in assemblage structure during increased physical disturbance is related to variation in a small number of numerically dominant species within the assemblage. At the individual taxon level, numerically dominant species in the seagrass and plankton showed considerable variation in response to disturbance. In the seagrass assemblage, post-larval King George whiting Sillaginodes punctata (Cuvier and Valenciennes), adult weedfish Heteroclinus perspicillatus (Cuvier and Valenciennes), and pipefish juveniles and adults from the genus Stigmatopora decreased in abundance at either one or both sites during high wave conditions. Conversely, in the plankton, adult pipefish Hypelognathus rostratus (Waite and Hale), juvenile Stigmatopora and larval Gymnapistes marmoratus (Cuvier and Valenciennes) significantly increased in abundance during these same physical conditions. It appears that for some taxa physical disturbance may facilitate secondary planktonic dispersal. KEY WORDS: Physical disturbance · Fish transport · Seagrass fishes · Post-settlement processesResale or republication not permitted without written consent of the publisher

“…Bivalve veligers typically have swimming speeds ranging from 0.17 to 2.00 mm S-' (Mann 1986, Wang & Xu 1997, are able to actively regulate depth, and perhaps undergo tidal-scale vertical migrations (Mann 1986). The extent to whlch veligers regulate transport through vertical migration in est'uarine systems is unclear, and dispersal strategies are highly variable.…”

Section: Introductionmentioning

confidence: 99%

“…A general pattern of ontogenetic shifts in vertical distribution is also apparent in species across different estuaries. Older larvae are generally more abundant near the bottom than younger larvae, presumably due to Increases in specific gravlty and changes in velum morphology (Mann 1986, Jacobsen et al 1990, Mann et al 1991, Baker 1993, Wang & Xu 1997. Higher abundance near the bottom enhances upstream transport in later life-history stages due to residual upstream movement of high salinity bottom waters (Pritchard 1952, Jacobsen et al 1990).…”

Section: Introductionmentioning

confidence: 99%

“…Juveniles range in size from 300 pm to several mm in length (Chanley & Andrews 1971). Traditionally, post-metamorphic bivalves were considered to be sessile after initial settlement; however, it is increasingly apparent that extensive dispersal can be accomplished, during the early juvenile or post-larval period (Armonies 1994, 1996, Baker & Mann 1997, Wang & Xu 1997. The period of post-larval dispersal is frequently longer than the larval period, suggesting that transport during this life-history stage may be extremely important to population dynamics (Baker & Mann 1997, Wang & Xu 1997.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Abundance and vertical distribution of drifting, post-larval Macoma spp. (Bivalvia:Tellinidae) in the York River, Virginia, USA

Garrison¹,

Morgan²

1999

We sampled the early drifting post-larvae of a complex of 2 species of tellinid bivalves, Macoma spp., at a station in the lower York River, Chesapeake Bay, USA. Plankton samples were collected by pump every 3 h from 3 depths (surface, mid-depth, and bottom) on 4 dates corresponding to full and new moons. Macoma spp. post-larvae (size range 400 to 500 pm) were abundant in the plankton throughout the sampling period. The environmental factors influencing the abundance and vertical distribution of drifting post-larvae were evaluated using linear and logistic regression. Post-larvae were always more abundant during night as compared to day and were more abundant during nocturnal, flooding tides than during ebbing tides. In general, they were closer to the surface at night and during flood tides, though these patterns were highly variable. These data indicate that drifting post-larval bivalves use 'selective tidal stream transport' to promote upstream dispersal as observed in the postlarvae of other estuarine taxa (e.g. crabs and fish). The post-larval stage generally re-invades juvenile habitats following the export of larvae to the mouth of the parent estuary or nearshore continental shelf. We suggest that small drifting post-larval bivalves exert behavioral control over suspension in the water column. This Life-history stage serves to maintain high densities of juveniles and adults in the upstream portions of the York River estuary despite downstream transport of early larval stages.