Recruitment and the Local Dynamics of Open Marine Populations

Abstract

The majority of marine populations are demographically open; their replenishment is largely or exclusively dependent on a supply of juveniles from the plankton. In spite of much recent research, no consensus has yet been reached regarding the importance of recruitment relative to other demographic processes in determining local population densities. We argue 1. that demographic theory suggests that, except under restrictive and unlikely conditions, recruitment must influence local population density to some extent. Therefore, 2. the question as to whether the size of a particular population is limited by recruitment is misguided. Finally, 3. the effect of recruitment on population size can be difficult to detect but is nonetheless real. A major weakness of most existing studies is a lack of attention to the survival of recruits over appropriate scales of time and space. Acknowledgment of the multifactorial determination of population density should guide the design of future experimental studies of the demography of open populations.

Spatial patterns of seed dispersal, their determinants and consequences for recruitment

“…To determine which features are important we need longer term, larger scale, integrated studies, of the kind that have generated crucial insights into marine systems 48 . These studies not only provide more information on variation among populations and individuals, across microsites, in time and at long distances from sources, but also link these to their consequences for recruitment.…”

Recruitment of coastal fishes and oceanographic variability in central California

“…Temporal and spatial variation in the rates of larval recruitment has long been recognized as a strong driver of marine populations and communities (Doherty and Williams, 1988;Doherty, 1991Doherty, , 2002Olaffson et al, 1994;Caley et al, 1996;Hixon and Webster, 2002). The ocean circulation processes that facilitate the transport of larvae to nearshore benthic habitats take place across a mosaic of spatial and temporal scales (Shanks, 1995;Caley et al, 1996) and have been implicated as key determinants of year class strength for a number of nearshore benthic species (Parrish et al, 1981;Hollowed et al, 1987).…”

Marine ecological research in seashore and seafloor systems:accomplishments and future directions

“…Although there is empirical evidence of defense and resistance for a variety of trophic levels, geographic regions, and modalities of defense, the most well-developed findings concern the role of secondary plant metabolites in plant-herbivore interactions w i t h tropicaYsubtropica1 reef systems. A final theme of conceptual importance is 'supply-side ecology'-the notion that dispersive life history stages (usually spores and larvae) significantly influence the population dynamics of adult stages in species with complex life cycles (Sale 1977, Doherty & Williams 1988, Roughgarden et al 1988, Underwood & Fairweather 1989, Caley et al 1996. Larval characteristics and physical transport processes are also important in explaining the rapid colonization of habitat patches in dynamically open systems, such as newly created hydrothermal vents (Mullineaux et al 1995).…”

“…An emerging scientific culture of ecological synthesis needs to be cultivated and supported. The rich informational base from past research in benthiddemersal systems seems ripe for such an approach, and recent examples are exciting and encouraging (Menge et al 1994, Caley et al 1996. A second opportunity is conducting experimental studies on varying spatial and temporal scales (Thrush et al 1997a,b).…”