Permanent boat moorings have contributed to the decline of seagrasses worldwide, prompting the development of 'seagrass-friendly' moorings. We contrasted seagrass cover and density (predominantly Posidonia australis) in the vicinity of three mooring types and nearby reference areas lacking moorings in Jervis Bay, Australia. We examined two types of 'seagrass-friendly' mooring and a conventional 'swing' mooring. 'Swing' moorings produced significant seagrass scour, denuding patches of ∼9 m radius. Seagrassfriendly 'cyclone' moorings produced extensive denuded patches (average radius of ∼18 m). Seagrass-friendly 'screw' moorings, conversely, had similar seagrass cover to nearby reference areas. Our findings reinforce previous work highlighting the negative effects of 'swing' and 'cyclone' moorings. In contrast, the previously unstudied 'screw' moorings were highly effective. We conclude that regular maintenance of moorings and the monitoring of surrounding seagrass are required to ensure that 'seagrass-friendly' moorings are operating effectively. This is important, as following damage Posidonia will take many decades to recover. AbstractPermanent boat moorings have contributed to the decline of seagrasses worldwide, prompting the development of 'seagrass-friendly' moorings. We contrasted seagrass cover and density (predominantly Posidonia australis) in the vicinity of three mooring types and nearby reference areas lacking moorings in Jervis Bay, Australia. We examined two types of 'seagrass-friendly' mooring and a conventional 'swing' mooring. 'Swing' moorings produced significant seagrass scour, denuding patches of ~9 m radius. Seagrass-friendly 'cyclone' moorings produced extensive denuded patches (average radius of ~18 m). Seagrass-friendly 'screw' moorings, conversely, had similar seagrass cover to nearby reference areas. Our findings reinforce previous work highlighting the negative effects of 'swing' and 'cyclone' moorings. In contrast, the previously unstudied 'screw' moorings were highly effective. We conclude that regular maintenance of moorings and the monitoring of surrounding seagrass are required to ensure that 'seagrass-friendly' moorings are operating effectively. This is important, as following damage Posidonia will take many decades to recover.

Despite the current global decline in seagrass, sessile epifaunal invertebrates inhabiting seagrass ecosystems, particularly sponges and ascidians, have been poorly studied due to their taxonomic complexity. Understanding patterns of distribution of sessile epifaunal communities in seagrass meadows is an important precursor to determining the processes driving their distribution and species interactions. This study (1) identified the sponge and ascidian assemblage associated with Posidonia australis meadows and (2) determined distributional patterns of these invertebrates at a hierarchy of spatial scales in Jervis Bay, Australia. We used a fully nested design with transects distributed in the seagrass (10s m apart), two sites (100s m apart), and six locations (km apart). Within these transects, we recorded the abundance, volume, diversity and substratum used for attachment by sponges and ascidians. We encountered 20 sponge species and eight ascidian species; they were sporadically distributed in the seagrass meadows with high variability among the transects, sites and locations. A few sponge and ascidian species dominated the assemblage and were widespread across the largest spatial scale sampled. The remaining species were mostly rare and sparsely distributed. Sponges attached to a variety of substrata but most notably shells, P. australis and polychaete tubes. No obligate seagrass species were recorded although three species predominantly used P. australis as a substratum. These sponge species relying heavily on seagrass for their attachment are likely prone to disturbances impacting their host habitat. Examining the response of sessile epifauna to the degradation of their seagrass habitat remains a key challenge for the future.

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SummaryPoorly studied species are potentially under‐prioritised by conservation programmes due to knowledge gaps presenting barriers to informing effective management strategies. The Botany Bay Bearded Greenhood, Pterostylis sp. Botany Bay, is an example of a poorly studied plant that is listed as endangered under both Commonwealth and New South Wales legislation. This study reports on archival surveys from 1998 to 2005 conducted at up to eight sites known to contain the Botany Bay Bearded Greenhood and follow‐up surveys in 2022. The archival surveys found that the total population count ranged from 83 to 341 individuals. Mean numbers (± standard error) of seedlings, flowering individuals and individuals exhibiting capsule development recorded in the population were 43 ± 14, 33 ± 9 and 2 ± 1 respectively. The 2022 surveys did not detect the species. An area of potential habitat was derived from records in biodiversity databases, which determined a total historical extent of 1.38 ha restricted to the Kurnell Peninsula in Sydney, New South Wales. The priority next step is to gather contemporary data to confirm whether the Botany Bay Bearded Greenhood remains extant, which can be done by applied researchers, students, landholders and land managers, botanical practitioners and/or volunteers. For optimal species detection, we recommend undertaking formal surveys or opportunistic searches in historically known sites and replicating detection efforts across July–September periods to exploit seasonal flowering.