Search

Soft corals from the Dendronephthya genus (family Nephtheidae) can change size over short periods by pumping water into their internal hydroskeletons. However, the drivers behind these size changes are not well understood. In a tidal-dominated estuary in eastern Australia, it was hypothesised that short-term changes in the size of Dendronephthya australis colonies occur in response to changes in tidal currents. This was tested by monitoring colonies over a period of several days using time-lapse photography. Colony extensions of up to 360 % were observed, and size changes exhibited a repeated pattern, with two maxima and two minima occurring in each tidal cycle, matching patterns in semi-diurnal tidal flows. A significant positive correlation between colony size and current velocity was identified, with size changes lagging currents. The results of the study provide valuable new information on the behaviour of D. australis and improve understanding of the environmental requirements for this species. Electronic supplementary material The online version of this article (doi:10.1007/s00227-015-2732-7) contains supplementary material, which is available to authorized users., Author(s): Tom R. Davis[sup.1] [sup.2] , David Harasti[sup.3] , Stephen D. A. Smith[sup.1] [sup.2] Author Affiliations: (1) National Marine Science Centre, Southern Cross University, PO Box 4321, 2450, Coffs Harbour, [...]

The temperate soft coral Dendronephthya australis has been listed as Endangered in NSW, Australia, owing to its restricted geographic range, rapidly declining populations, and a number of escalating threats. Research to assess practical methods for aquarium cultivation of D. australis for rehabilitation of wild populations is considered a high priority.Previous attempts at restoration by transplanting D. australis fragments have had limited success, but identified key challenges, which included achieving attachment to substrates and identifying appropriate foods to maximize survival.This study presents the results of experiments promoting the attachment of cuttings (nubbins) removed from donor colonies to moveable substrates (small concrete discs). Using a balanced orthogonal experimental design, three feeding regimes were tested: live artemia, live rotifers and dry powdered zooplankton.Donor colony survival and growth were also monitored over a 6 month period in the field.An overall nubbin survival rate of 100% was achieved under all three feeding regimes. Attachment rates were similar across feeding treatments, although nubbin behavioural responses (percentage of open polyps before feeding) suggested some preference for live rotifers.The cutting removal process had no significant effect on donor colonies in the wild, indicating that this is a sustainable approach for restoration.Overall, this study substantially advances the methodology for maintaining an Endangered azooxanthellate soft coral in aquaria and provides valuable input for management programmes aimed at implementing transplantation into the wild to aid species recovery. [ABSTRACT FROM AUTHOR]

Climate change has driven contemporary decline and loss of kelp forests globally with an accompanying loss of their ecological and economic values. Kelp populations at equatorward-range edges are particularly vulnerable to climate change as these locations are undergoing warming at or beyond thermal tolerance thresholds. Concerningly, these range-edge populations may contain unique adaptive or evolutionary genetic diversity that is vulnerable to warming. We explore haplotype diversity by generating a Templeton–Crandall–Sing (TCS) network analysis of 119 Cytochrome C Oxidase (COI) sequences among four major population groupings for extant and putatively extinct populations only known from herbarium specimens of the dominant Laminarian kelp Ecklonia radiata in the south-western Pacific, a region warming at 2–4 times the global average. Six haplotypes occurred across the region with one being widespread across most populations. Three unique haplotypes were found in a deep-water range-edge population off Moreton Island, Queensland, which likely represents both a contemporary and historic refuge during periods of climatic change. Hindcasting E. radiata cover estimates using extant data, we reveal that this region likely supported the highest kelp cover in eastern Australia during the last glacial maximum. The equatorward range edge, deep-water kelp populations off Moreton Island represent a genetically diverse evolutionary refuge that is currently threatened by warming and requires prompt ex-situ conservation measures. [ABSTRACT FROM AUTHOR]

Biodiversity surveys of marine species are largely conducted during the day, and often over relatively short timeframes, due to practical, operational, and budgetary constraints. As a consequence, surveys can underestimate biodiversity for some groups, such as heterobranch (formerly opisthobranch) molluscs, where abundances vary seasonally by orders of magnitude and different species are active at different times of the day. Here, we quantitatively assess day/night (diel) and seasonal variation in heterobranch sea slug assemblages using monthly, diel scuba surveys for 13 months at three sites in Port Stephens, New South Wales (NSW). All heterobranch sea slugs encountered in 50 × 5-m belt transects were recorded using identical survey methods both during the day and at night. Significant differences were detected between day and night assemblages, with species richness and abundance being consistently higher at night. Significant cyclical patterns were also detected in sea slug assemblages over the duration of the study, for both day and night assemblages, with species assemblages changing throughout the study period. The results demonstrate that marine diversity studies conducted only during the day, and those which do not account for all seasons, are likely to underestimate diversity and abundance of molluscs, particularly heterobranch sea slugs. It is, therefore, important that studies which aim to provide a comprehensive catalogue of molluscan biodiversity include not only day-time surveys, but also those conducted at night. They should also include temporal replication in order to capture ephemeral species. [ABSTRACT FROM AUTHOR]

Effective estuarine management depends on adequate data about the ecology, extent and biodiversity of component habitats. However, these data are often scant, as exemplified by the Port Stephens estuary, part of the Port Stephens-Great Lakes Marine Park (NSW, Australia), for which even basic descriptions of habitat types and extent are lacking. Herein we present the results of the first quantitative assessment of subtidal benthic communities within the estuary, involving 130 km of towed video transects over an area exceeding 50 km². We identified previously undocumented macroalgae-dominated habitat types and found strong correlations between habitat types and depth. The soft coral Dendronephthya australis habitat is of particular interest because this was found to occur exclusively outside current sanctuary (no take) zones. The habitat map of Port Stephens generated during the study provides the basis for more objective representative planning in future iterations of zoning in the estuarine section of the marine park. The study also suggests that depth may be a useful proxy for estuarine habitat types where specific data are lacking. The classification methodology developed during the study was cost-effective, generated robust data and consequently has potential for wider application in other large estuarine bays. [ABSTRACT FROM AUTHOR]

Soft coral aggregations provide an important habitat for fish and invertebrates in both temperate and tropical marine environments [[3]], and restoration of these habitats is important for maintaining regional biodiversity. In recent decades, the transplantation of corals has been a primary focus of restoration strategies in areas where coral populations have declined [[1]]. [Extracted from the article]

Globally, anthropogenic climate change has caused declines of seagrass ecosystems necessitating proactive restoration approaches that would ideally anticipate future climate scenarios, such as marine warming. In eastern Australia, estuaries with meadows of the endangered seagrass Posidonia australi s have warmed and acidified over the past decade, and seagrass communities have declined in some estuaries. Securing these valuable habitats will require proactive conservation and restoration efforts that could be augmented with restoration focussed on boosting resilience to future climate. Understanding patterns of selection and where seagrass meadows are adapted to particular environmental conditions is key for identifying optimal donor material for restoration. We used single nucleotide polymorphisms and genotype by environment analyses to identify candidate loci under putative selection to environmental stressors and assess genomic variation and allelic turnover along stressor gradients. The most important physicochemical variables driving selection were associated with temperature, water turbidity, and pH. We developed a preliminary 'donor registry' of pre-adapted P. australis genotypes by mapping the distribution of alleles to visualise allelic composition of each sampled seagrass meadow. The registry could be used as a first step to select source material for future-proofing restoration projects. A next step is to establish manipulative experiments that will be required to test whether pre-adapted genotypes confer increased resistance to multiple environmental stressors., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)