Go with the flow: tidal import and export of larvae from semi-enclosed bays

Abstract

There is a growing body of evidence that suggests the effective functioning of marine reserves is dependent on the dispersal and recruitment of larvae. Enhanced production inside reserves is predicted to lead to a net larval export and increased settlement and recruitment outside reserve boundaries. However, larval retention in bays is also well documented. Since bays are increasingly being used as reserve areas, planktonic larvae of benthic marine invertebrates were sampled from two semi-enclosed marine reserves during flood and ebb tides to determine whether these bays are acting as net exporters of larvae. Neither reserve was a net importer or exporter of species richness, larval abundance or diversity, although one reserve showed a small export of species richness during the hours of darkness. Both reserves balanced the net import of some species with a net export of others, which was generally related to adult or larval abundance, although exceptions were found in one reserve. Significant effects of light were found, with the net import or export of some species occurring exclusively during either the hours of daylight or darkness. An increased understanding of larval sink-source dynamics in bays is essential for ensuring their effective use as marine reserves to meet specific conservation needs.

Comparison of Inorganic and Organic Matter Sedimentation in a Natural Laboratory: A One-Year Study at Lough Hyne Marine Reserve, Ireland

“…In the present study it was possible to hypothesise where OM was coming from at different stages of the study period. Previous studies on both, phyto-and zooplankton in Lough Hyne [18,19], have shown that both components of the plankton community are produced inside Lough Hyne but that some are also brought in from the outside. Nutrients have been shown to be brought in from the outside, causing increased occurrences of red tides even in the winter months, and year-round high levels of nutrients [10,20].…”

The Effect of Tidal Cycles on the Community Structure of Plankton (with Emphasis on Copepods) at Afmed Marina in Winter (A Preliminary Study)

“…This behaviour will lead to their accumulation at frontal zones (Simard et al, 1986;Olson et al, 1994;Genin et al, 2005), and it shows how oceanic fronts can become major feeding grounds for predators, and hence targets for fisheries (Genin et al, 2005). On the other hand, nearshore fronts Shanks et al, 2003) might limit larval dispersal, and the observed local recruitment of species with long-lived larvae (Palumbi, 1999(Palumbi, , 2003 certainly supports this assumption (Jessopp & McAllen, 2008). The ability of zooplankton to affect horizontal transport by adjusting their vertical position in the water column (Kimmerer & McKinnon, 1987), can enhance their retention or dispersal in bays and could lead to a selective advantage (Hill, 1991).…”

“…While the active dispersal of larvae, away from adult populations to suitable nursery grounds, can be achieved by this process (DiBacco et al, 2001;Garland et al, 2002), the same process can be utilized to limit transport and prevent offshore advection (Shanks & Brink, 2005). In addition, ebb tides have been found to show significantly higher species richness than flood tides during the hours of darkness, but no significant difference was found during the day (Jessopp & McAllen, 2008).…”

Seasonal, lunar and tidal control of ichthyoplankton dynamics at the interface between a temperate estuary and adjacent coastal waters (western Portugal)

“…Retention mechanisms and selective tidal-stream transport (STT) have been imputed to several species of zooplankton, larval benthic invertebrates (e.g. Queiroga et al 2007, Jessopp and McAllen 2008, Marques et al 2009) and larval and juvenile fishes (Schultz et al 2003, Miller and Shanks 2004, Islam et al 2007.…”

“…Mechanisms of fish larvae ingress and retention in nurseries areas are the focus of several studies across North America (Epifanio and Garvine 2001, Hare et al 2005, Rooper et al 2006, Japan (Islam et al 2007) and Europe (Jager 1999, 2001, Jessopp and McAllen 2008. Little is known concerning the influence of endogenous rhythms associated with the lunar-tide cycle on larval entrance and consequent up-estuary transport and horizontal distribution inside these nurseries areas.…”