Port Phillip Bay (PPB) is a large (1,930 km 2 ), temperate embayment in southern Victoria, Australia. Extensive bay-wide surveys of PPB have occurred since 1840. In 1995/1996 the Commonwealth Scientific and Industrial Research Organization (CSIRO) Centre for Research on Introduced Marine Pests (CRIMP) undertook an intensive evaluation of the region with the aims of developing a comprehensive species list of native and introduced biota and contrasting previous bay-wide assessments with a current field survey in order to detect new incursions and discern alterations to native communities. Two methods were used to meet these aims: a re-evaluation of regional museum collections and published research in PPB to identify and determine the timing of introductions; and field surveys for benthic (infauna, epifauna and encrusting) organisms between September 1995 to March 1996. One hundred and sixty introduced (99) and cryptogenic (61) species were identified representing over 13% of the recorded species of PPB. As expected, the majority of these are concentrated around the shipping ports of Geelong and Melbourne. Invasions within PPB appear to be increasing, possibly due to an increase in modern shipping traffic and an increase in aquaculture (historically associated with incidental introductions); however the records of extensive biological surveys suggest that this may, in part, be an artefact of sampling effort. In contrast to Northern Hemisphere studies, PPB (and Southern Hemisphere introductions in general) have significantly different suites of successfully invading taxa. PPB is presented as one of the most invaded marine ecosystems in the Southern Hemisphere.

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The identity o\' two common Australian

Monotheca Nutting, 1900 is a genus with few known species worldwide. It is an artificial genus, as some species of the Plumulariidae sometimes have one or two hydrocladial hydrothecae and are thus borderline between Monotheca and Plumularia. This review considers only Australian species with consistently monothecate hydrocladia; species with more than one hydrotheca on the hydrocladium are considered to belong to Plumularia. Ten species referrable to Monotheca are reported from southeast Australia; three are synonymised here in other species, four are presently known to be endemic to Australia and one species, Monotheca amphibola, is described as new. The gonosome of Monotheca togata is described for the first time. Monothecella is synonymised in Monotheca. A key to the Australian species of Monotheca is given.

The long-term impacts of declining water quality from coastal development on macro-algal communities can be devastating, but are rarely known because of lack of baseline studies. This study examines the effect of increased sediment and reduced water quality over 35 years in an Australian temperate coastal embayment. The algal assemblage on Crawfish Rock in northern Western Port was surveyed in 1967–1971 and in 2002–2006. During the 1980s, water quality declined following large-scale seagrass loss. In 1971, the Rock had a rich algal flora with 138 recorded species, including 97 species of Rhodophyta. The biomass and cover of canopy and understorey species were measured at sites of strong and slight current on a depth gradient. In 1971, fucoid or laminarian canopy species were dominant from ∼1–8 m depth, and an algal understorey extended from the intertidal zone to 12–13 m depth. In 2002–2006 the canopy species extended to only 3 m depth and the algal understorey to ∼4 m depth, and 66% of the algal species had disappeared, although a few additional species were present. Persistent, sediment-tolerant species included several phaeophycean canopy species, some chlorophytes (Caulerpa spp.) and a few rhodophytes.