Abundance, recruitment and residency of two sparids in an intermittently open estuary in South Africa

  • NC James South African Environmental Observation Network, Private Bag 1015, Grahamstown 6140, South Africa
  • PD Cowley South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa
  • AK Whitfield South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa

Abstract

The recruitment of distinct year-class cohorts in two sparid species, Rhabdosargus holubi and Lithognathus lithognathus, were linked to records of daily mouth state in the intermittently open East Kleinemonde Estuary, South Africa, between 1995 and 2006. L. lithognathus only recruited into the estuary in years when the mouth opened between late August and January. This was attributed to a limited spawning season and inability to recruit during wave overwash events. In contrast, R. holubi recruitment was uninterrupted and not influenced by seasonality of estuary access opportunities (mouthopening and overwash events). Estuarine-dependent residency periods ranged from 27 months to 48 months for L. lithognathus and 12 months to 23 months for R. holubi. The interannual abundances of these estuarydependent sparids were determined by reproductive seasonality, recruitment strategy and seasonal timing of estuarine access opportunities.

Keywords: East Kleinemonde Estuary, Lithognathus lithognathus, long-term trends, recruitment, Rhabdosargus holubi

African Journal of Marine Science 2007, 29(3): 527–538
Published
2008-02-07
Section
Articles

Journal Identifiers


eISSN: 1814-2338
print ISSN: 1814-232X