The feeding ecology and seasonal pattern of occurrence of the 0 + year classes of the fish Aldrichetta forsteri, Cnidoglanis macrocephalus, Sillago bassensis, and Arripis georgianus were investigated to determine relationships between these economically important species and surf-zone accumulations of detached macrophytes along the coast of Western Australia. The main prey of A. forsteri, C. macrocephalus and A. georgjanus and the second most important prey of S. bassensis was the arnphipod Allorchestes cornpressa; the distribution of A. compressa was restricted to detached plants in the surf-zone. The arrival in winter, of 3 of the fish species on the open coast corresponded with the period of greatest deposition of detached plants in the nearshore zone, and there appeared to b e sufficient plant material, and associated amphipods, to support fish during summer. The large patches of vegatation in the surf-zone of sandy beaches support densities of A. compressa up to a mean of 110 g-' dry wt vegetation and provide an alternative feeding habitat for these benthic feeders, one of which is restricted to estuaries in other regions of Australia. It is also likely that this vegetation provides shelter from potential predators such a s diving birds and larger fish.

The diet of Hyporhamphus melanochir underwent shifts from green eelgrass (Zosteraceae) tissue during the day to mainly benthic dwelhng amphipods and other invertebrates at night. The shifts occurred sharply at dawn and dusk and were observed in all size groups of the fish (range of lengths 10.0 to 29.8 cm). H. melanochir probably took detached eelgrass leaves from the water column durlng the day but may also have grazed live eelgrass. Feeding on benthic dwelling amphipods was facilitated by nocturnal vertical migration of these prey. Animals, particularly crustaceans, but also Insects, appear to be the preferred prey of garfish. Eelgrass 1s probably consumed during the day because crustacean prey are rare in the water column at that time. The feeding strategy of H. melanochir appears to be an adaptation to diel changes in food ava~lability as well as the fishes' metabolic requirements

No abstract

Zooplankton was sampled in a mangrove forest, a mangrove drainage creek, the mainstream of a mangrove-dominated estuary, an adjacent seagrass flat and at an offshore (10 km) station in northeastern Australia every 6 wk between April 1985 and February 1986. Copepods, in particular Parvocalanus crassirostris, Paracalanus spp., several species of Oithona and Euterpina acutifrons, were numerically dominant. Community structure often differed amongst mangrove habitats, but mangrove habitats clustered separately from seagrass and bay habitats in classification analyses due to the abundance of meroplankton taxa, particularly invertebrate eggs and brachyuran zoea, in mangrove habitats. Total densities of zooplankton in mangrove and seagrass habitats (range of mean annual densities, 1.13 to 1.97 X 104 m-3) were always higher than in the offshore bay habitat (F = 0.88 X 104 m-3). Mangrove and seagrass habitats exhibited marked seasonality in densities of most taxa (for total zooplankton typically ca 2 to 6 X 104 m-3 in the wet season to ca 0.1 to 5 x 103 m-3 in the dry season). Generally, seasonality in most taxa did not correlate with water temperature, salinity, mangrove litter fall or fish predation, although fish may have a significant influence on brachyuran zoea. There were often significant tidal variations in densities in mangrove creeks; low-tide densities were usually lower than high-tide values. Comparisons of the density of major prey taxa of fish in seagrass and mangrove habitats gave only partial support to the hypothesis that mangroves are more important nursery sites for zooplankton-feeding juvenile fish because they are areas of greater food abundance; during the summer recruitment period of juvenile fish, brachyuran zoea, a major prey of fish, were an order of magnitude more abundant in mangrove habitats.

Spring establishment and herbage production of sheep's burnet (~ang~isorba mino: ssp. muricata) were compared with blf?sfoot tre~011 (Lotus corniculatus) and lucerne (Medicago sativa) at Riverside in the lower North Island of New Zealand. The trial includedbinary mixturesof sheep's burnet and the legumes. Emergence of similar swards was also investigated at Flock House, a warmer site, in the lower North Island. Emergence of the three species was similar at each site but for sheep's burnet at Flock House (66.2%), it was greater than that at Riverside (26.5%). Both legumes emerged faster than sheep's burnet with lucerne being the quickest. The results suggested that sheep's burnet is best sown alone or with other slowly emerging species. Early foliar dry weight and leaf area of sheep's burnet and lucerne were similar and greater than that of birdsfoot trefoil. However, over three summer mowings (7-8 em high), total herbage mass for all pure and mixed swards was similar and averaged 6.3 t DM/ha. Sheep's burnet provided useful ground cover and forage mass.