Ecology of Benthic Polychaetes in the Heathcote Estuary
ECOLOGY OF BENTHIC POLYCHAETES IN THE HEATHCOTE ESTUARY, NEW ZEALAND
I. N. ESTCOURT
New Zealand Oceanographic Institute, Department of Scientific and Industrial Research, Wellington
(Received for publication 20 March 1967)
SUMMARY
The distributions of 19 species of polychaetes burrowing in the intertidal sand and mudbanks of the Heathcote Estuary, New Zealand, are related to salinity, sediment grade, and length of time of exposure at low tide. Only Nicon aestuariensis Knox and Scotecolepides benhami Ehlers appear to be truly estuarine species reaching their greatest population densities in low salinities. Incidental observations of feeding and reproduction are reported.
INTRODUCTION
There have been very few studies of the biology of estuarine animals in New Zealand. The estuarine environment is characterised by steep and variable gradients in environmental factors, and the fauna tends to be specialised to tolerate these conditions (Emery and Stevenson 1957).
In this survey of the polychaetes of the intertidal mudbanks of the Heathcote Estuary the distribution of each species was found to be related to the salinity of the water, the nature of the substratum, and the length of time of exposure to air at low tide. Some observations of feeding habits and reproduction were made. Systematic notes and a key to the species whose ecology is discussed in this paper have appeared elsewhere (Estcourt 1967), and also a description (Estcourt 1966) of the breeding biology of one of them.
Comparatively little work has been done on the biology of the estuary of the Heathcote and Avon Rivers. Thompson (1929) made the first general study and there have since been studies by Bruce (1953), Williams (1960), and Rosenberg (1963) carried out for the Christchurch Drainage Board and principally concerned with the effect of pollution on the biota.
THE HEATHCOTE ESTUARY
The estuary of the Heathcote and Avon Rivers (Fig. 1) near Christchurch lies immediately north of the volcanic
I. N. ESTCOURT
New Zealand Oceanographic Institute, Department of Scientific and Industrial Research, Wellington
(Received for publication 20 March 1967)
SUMMARY
The distributions of 19 species of polychaetes burrowing in the intertidal sand and mudbanks of the Heathcote Estuary, New Zealand, are related to salinity, sediment grade, and length of time of exposure at low tide. Only Nicon aestuariensis Knox and Scotecolepides benhami Ehlers appear to be truly estuarine species reaching their greatest population densities in low salinities. Incidental observations of feeding and reproduction are reported.
INTRODUCTION
There have been very few studies of the biology of estuarine animals in New Zealand. The estuarine environment is characterised by steep and variable gradients in environmental factors, and the fauna tends to be specialised to tolerate these conditions (Emery and Stevenson 1957).
In this survey of the polychaetes of the intertidal mudbanks of the Heathcote Estuary the distribution of each species was found to be related to the salinity of the water, the nature of the substratum, and the length of time of exposure to air at low tide. Some observations of feeding habits and reproduction were made. Systematic notes and a key to the species whose ecology is discussed in this paper have appeared elsewhere (Estcourt 1967), and also a description (Estcourt 1966) of the breeding biology of one of them.
Comparatively little work has been done on the biology of the estuary of the Heathcote and Avon Rivers. Thompson (1929) made the first general study and there have since been studies by Bruce (1953), Williams (1960), and Rosenberg (1963) carried out for the Christchurch Drainage Board and principally concerned with the effect of pollution on the biota.
THE HEATHCOTE ESTUARY
The estuary of the Heathcote and Avon Rivers (Fig. 1) near Christchurch lies immediately north of the volcanic
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