ORCID Profile
0000-0001-8612-8600
Current Organisations
James Cook University
,
The University of Newcastle
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Publisher: Elsevier BV
Date: 10-2017
Publisher: Wiley
Date: 05-06-2019
DOI: 10.1111/FME.12351
Publisher: Wiley
Date: 25-09-2020
DOI: 10.1111/REC.13269
Publisher: Frontiers Media SA
Date: 29-06-2018
Publisher: Wiley
Date: 09-01-2018
DOI: 10.1111/GEB.12713
Publisher: Springer Science and Business Media LLC
Date: 02-11-2014
Publisher: Wiley
Date: 16-05-2011
DOI: 10.1111/J.1095-8649.2011.02977.X
Abstract: Diets of the pipefish Stigmatopora nigra were analysed to determine if food availability was causing S. nigra to distribute according to habitat edge effects. Gut analysis found little difference in the diets of S. nigra at the edge and interior of seagrass patches, regardless of time of day or season. Fish diets did, however, vary with seagrass density: S. nigra in denser seagrass consumed more harpacticoid copepods and fewer planktonic copepods. The lack of difference in prey eaten by S. nigra at the edge and interior of patches suggests either that food was not determining S. nigra distribution patterns within patches or that differences in fish densities across patches meant that relative fish-prey densities were similar at edge and interior positions. Alternatively, any edge effects in diet might be masked by gradients in seagrass structure.
Publisher: Inter-Research Science Center
Date: 05-05-2008
DOI: 10.3354/MEPS07348
Publisher: Elsevier BV
Date: 05-2020
Publisher: CSIRO Publishing
Date: 03-05-2023
DOI: 10.1071/MF22103
Abstract: Context Primary production on coral reefs varies under changing conditions such as light and nutrient availability. This variation causes changes in basal stable isotopes as photosynthetic and nutrient pathways change. Aims This study provides a preliminary baseline of nitrogen (δ15N) and carbon (δ13C) stable isotope profiles in Symbiodinium and macroalgae at a spatial scale and along a depth gradient around an island. Methods Coral fragments and macroalgae were collected at depths from the surface to 26 m. δ15N and δ13C stable isotope values were assessed for Symbiodinium relative to cell density per surface area. Key results δ15N values showed a uniform nutrient profile across primary producers. However, chlorophyll-a and Symbiodinium density from Montipora stellata had higher concentrations on the southern side of the island. δ15N values of Symbiodinium from Stylophora pistillata and macroalgae did not change with depth. Depth was associated with a significant decrease in Symbiodinium density, and δ13C values in macroalgae. Conclusions We attribute these findings to Symbiodinium from S. pistillata as depth increases, decreasing cell density but maintaining chlorophyll-a concentration to satisfy the coral-host nutrient requirements. Implications This study sets the scene for future, more comprehensive research on detecting carbon and nitrogen stable isotope values on primary producers in coral reefs.
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.MARENVRES.2016.08.010
Abstract: In marine environments characterised by habitat-forming plants, the relative allocation of resources into vegetative growth and flowering is an important indicator of plant condition and hence ecosystem health. In addition, the production and abundance of seeds can give clues to local resilience. Flowering density, seed bank, biomass and epiphyte levels were recorded for the temperate seagrass Zostera nigricaulis in Port Phillip Bay, south east Australia at 14 sites chosen to represent several regions with different physicochemical conditions. Strong regional differences were found within the large bay. Spathe and seed density were very low in the north of the bay (3 sites), low in the centre of the bay (2 sites) intermediate in the Outer Geelong Arm (2 sites), high in Swan Bay (2 sites) and very high in the Inner Geelong Arm (3 sites). In the south (2 sites) seed density was low and spathe density was high. These regional patterns were largely consistent for the 5 sites s led over the three year period. Timing of flowering was consistent across sites, occurring from August until December with peak production in October, except during the third year of monitoring when overall densities were lower and peaked in November. Seagrass biomass, epiphyte load, canopy height and stem density showed few consistent spatial and temporal patterns. Variation in spathe and seed density and morphology across Port Phillip Bay reflects varying environmental conditions and suggests that northern sites may be restricted in their ability to recover from disturbance through sexual reproduction. In contrast, sites in the west and south of the bay have greater potential to recover from disturbances due to a larger seed bank and these sites could act as source populations for sites where seed production is low.
Publisher: Elsevier BV
Date: 12-2012
Publisher: Elsevier BV
Date: 06-2017
DOI: 10.1016/J.MARENVRES.2016.06.006
Abstract: Seagrass species form important marine and estuarine habitats providing valuable ecosystem services and functions. Coastal zones that are increasingly impacted by anthropogenic development have experienced substantial declines in seagrass abundance around the world. Australia, which has some of the world's largest seagrass meadows and is home to over half of the known species, is not immune to these losses. In 1999 a review of seagrass ecosystems knowledge was conducted in Australia and strategic research priorities were developed to provide research direction for future studies and management. Subsequent rapid evolution of seagrass research and scientific methods has led to more than 70% of peer reviewed seagrass literature being produced since that time. A workshop was held as part of the Australian Marine Sciences Association conference in July 2015 in Geelong, Victoria, to update and redefine strategic priorities in seagrass research. Participants identified 40 research questions from 10 research fields (taxonomy and systematics, physiology, population biology, sediment biogeochemistry and microbiology, ecosystem function, faunal habitats, threats, rehabilitation and restoration, mapping and monitoring, management tools) as priorities for future research on Australian seagrasses. Progress in research will rely on advances in areas such as remote sensing, genomic tools, microsensors, computer modeling, and statistical analyses. A more interdisciplinary approach will be needed to facilitate greater understanding of the complex interactions among seagrasses and their environment.
Publisher: Springer Science and Business Media LLC
Date: 05-12-2013
Publisher: Wiley
Date: 11-12-2009
DOI: 10.1111/J.1365-2656.2009.01605.X
Abstract: 1. Patch area and proximity of patch edge can influence ecological processes across patchy landscapes and may interact with each other. Different patch sizes have different amounts of core habitat, potentially affecting animal abundances at the edge and middle of patches. In this study, we tested if edge effects varied with patch size. 2. Fish were s led in 10 various-sized seagrass patches (114-5934 m(2)) using a small (0.5 m(2)) push net in three positions within each patch: the seagrass edge, 2 m into a patch and in the middle of a patch. 3. The two most common species showed an interaction between patch size and the edge-interior difference in abundance. In the smallest patches, pipefish (Stigmatopora nigra) were at similar densities at the edge and interior, but with increasing patch size, the density at the edge habitat increased. For gobies (Nesogobius maccullochi), the pattern was exactly the opposite. 4. This is the first ex le from a marine system of how patch size can influence the magnitude and pattern of edge effects. 5. Both patch area and edge effects need to be considered in the development of conservation and management strategies for seagrass habitats.
Publisher: PeerJ
Date: 23-03-2017
DOI: 10.7717/PEERJ.3114
Abstract: In a series of experiments, seeds from a temperate seagrass species, Zostera nigricaulis collected in Port Phillip Bay, Victoria, Australia were exposed to a range of salinities (20 PSU pulse/no pulse, 25 PSU, 30 PSU, 35 PSU), temperatures (13 °C, 17 °C, 22 °C), burial depths (0 cm, 1 cm, 2 cm) and site specific sediment characteristics (fine, medium, coarse) to quantify their impacts on germination rate and maximum overall germination. In southern Australia the seagrass Z. nigricaulis is a common subtidal species however, little is known about the factors that affect seed germination which is a potential limiting factor in meadow resilience to natural and anthropogenic disturbances. Overall seed germination was low ( %) with germination decreasing to % when seeds were placed in the sediment. When germination of Z. nigricaulis seeds was observed, it was enhanced (greater overall germination and shorter time to germination) when seeds were exposed to a 20 PSU pulse for 24 h, maintained at salinity of 25 PSU, temperatures °C, in sediments with fine or medium grain sand and buried at a depth of cm. These results indicate that germination of Z. nigricaulis seeds under in situ conditions may be seasonally limited by temperatures in southern Australia. Seed germination may be further restricted by salinity as freshwater pulses reaching 20 PSU are typically only observed in Port Phillip Bay following large scale rainfall events. As a result, these populations may be particularly susceptible to disturbance with only a seasonally limited capacity for recovery.
Publisher: Springer Science and Business Media LLC
Date: 03-02-2013
Publisher: Springer International Publishing
Date: 2018
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 03-2011
Publisher: Springer Science and Business Media LLC
Date: 09-02-2023
DOI: 10.1038/S41598-023-29147-1
Abstract: Report cards that are designed to monitor environmental trends have the potential to provide a powerful communication tool because they are easy to understand and accessible to the general public, scientists, managers and policy makers. Given this functionality, they are increasingly popular in marine ecosystem reporting. We describe a report card method for seagrass that incorporates spatial and temporal variability in three metrics—meadow area, species and biomass—developed using long-term (greater than 10 years) monitoring data. This framework summarises large amounts of spatially and temporally complex data to give a numeric score that provides reliable comparisons of seagrass condition in both persistent and naturally variable meadows. We provide an ex le of how this is applied to seagrass meadows in an industrial port in the Great Barrier Reef World Heritage Area of north-eastern Australia.
Publisher: Springer Science and Business Media LLC
Date: 08-04-2022
DOI: 10.1007/S10750-022-04873-1
Abstract: Seed size can have an impact on angiosperm reproductive fitness. Ecological theory predicts plants that will produce larger seeds in stressful environments to increase the chances of seedling survival and numerous small seeds in favourable conditions to increase the number of recruits. We measured seed morphology of the seagrass Heterozostera nigricaulis from four populations under differing environmental conditions in South East Australia. Seed size and mass among sites showed consistent differences over four flowering seasons. Seeds from exposed, ephemeral meadows (Blairgowrie, Edwards Point) were 19%–53% heavier than those from larger, stable meadows at more sheltered sites (Swan Bay, Point Henry). Overall, heavier seeds from exposed sites performed better in germination experiments and persisted (remained viable) longer compared to small seeds from sheltered sites. Seeds from sheltered sites showed contrasting levels of seed performance. Small seeds from Swan Bay had the lowest germination but the proportion of viable seeds after 12 months were much higher (41%) than similar sized seeds from Point Henry (0%). There are clear life history benefits of large seeds that facilitate seed persistence and germination at exposed sites however, the performance of smaller seeds varied between sites and may be a function of other site-specific advantages.
Publisher: Wiley
Date: 19-08-2021
DOI: 10.1002/RCM.9167
Abstract: Stable isotopes are used to study trophic and movement ecology in aquatic systems, as they provide spatially distinct, time‐integrated signatures of diet. Stable isotope ecology has been used to quantify species‐habitat relationships in many important fisheries species (e.g., penaeid prawns), with approaches that typically assume constant values for diet‐tissue discrimination and diet‐tissue steady state, but these can be highly variable. Here we provide the first report of these processes in Metapenaeus macleayi (eastern school prawn). Here we explicitly measure and model carbon (δ 13 C) and nitrogen (δ 15 N) diet‐tissue discrimination and turnover in eastern school prawn muscle tissue as a function of experimental time following a change in diet to an isotopically distinct food source. Diet‐tissue discrimination factors were 5 and 0.6‰ for δ 13 C and δ 15 N, respectively. Prawn muscle tissue reached an approximate steady state after approximately 50 and 30 days for δ 13 C and δ 15 N. Half‐lives indicated faster turnover of δ 15 N (~8 days) than δ 13 C (~14 days). Our diet‐tissue discrimination factors deviate from ‘typical’ values with larger values for carbon than nitrogen isotopes, but are generally similar to those measured in other crustaceans. Similarly, our estimates of isotopic turnover align with those in other penaeid species. These findings confirm muscle tissue as a reliable indicator of long‐term diet and movement patterns in eastern school prawn.
Publisher: Wiley
Date: 09-03-2022
DOI: 10.1111/AEC.13160
Abstract: The endangered soft coral Dendronephthya australis faces substantial population decreases in central eastern Australian waters. Despite uncertainty about the cause of these declines, the population genetics of the species has not been investigated. Genetic analysis suggests that D. australis is a single species within the family Nephtheidae, confirming identifications based on morphological characteristics only. Soft coral colonies were distributed from Seahorse Gardens in Port Stephens to Jervis Bay in temperate Australian waters, a distance of some 400 km. Genetic differentiation was observed along this distribution using SNP genotyping. Relatively high levels of genetic differentiation were observed between Jervis Bay and the other sites, indicating limited gene flow between this location and others. Moreover, the genetic distinctiveness, low ersity and heterozygote excess at this southern location suggested that it was subjected to a recent population decline and genetic bottleneck. Colonies at Seahorse Gardens and Ettalong, approximately 150 km south of Seahorse Gardens, displayed greater genetic ersity, making these sites more likely to host ancestral populations and to have acted as refugia. Recent substantial decreases in population sizes at these locations are particularly concerning, and these locations require immediate conservation attention.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 02-2019
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/MF14328
Abstract: The southern calamary, Sepioteuthis australis, is a commercially and recreationally important inshore cephalopod endemic to southern Australia and New Zealand. Typical of other cephalopods, S. australis has a short life span, form nearshore spawning aggregations and undergo direct development. Such life history traits may restrict connectivity between spawning grounds creating highly structured and genetically differentiated populations that are susceptible to population crashes. Here we use seven polymorphic microsatellite markers to assess connectivity and population structure of S. australis across a large part of its geographic range in Australia. Little genetic differentiation was found between s ling locations. Overall, FST was low (0.005, 95% CI= .001–0.011) and we detected no significant genetic differentiation between any of the locations s led. There was no strong relationship between genetic and geographical distance, and our neighbour joining analysis did not show clustering of clades based on geographical locations. Similarly, network analysis showed strong connectivity amongst most locations, in particular, Tasmania appears to be well connected with several other locations and may act as an important source population. High levels of gene flow and connectivity between S. australis s ling sites across Australia are important for this short-lived species, ensuring resilience against spatial and temporal mortality fluctuations.
Publisher: Inter-Research Science Center
Date: 2005
DOI: 10.3354/MEPS294257
Publisher: Springer International Publishing
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 21-03-2016
Publisher: Wiley
Date: 15-03-2023
DOI: 10.1111/OIK.09520
Abstract: Plant–herbivore interactions are often regulated by a series of direct and indirect buffer mechanisms (compensatory or defensive plant responses, population control, alternative resources) that can determine the relative stability of the system. In plant‐dominated marine environments, these mechanisms are particularly important given how vulnerable these systems are to strong consumer pressure. Here, we evaluate the presence and, where possible, the strength, of five mechanisms that get activated under high herbivory pressure and are capable of d ening their effects in a seagrass meadow ecosystem: 1) seagrass compensatory growth, 2) increase in plant resistance, 3) availability of alternative resources, 4) predatory control and 5) density‐dependent control. We assessed these mechanisms for the interaction between the Mediterranean seagrass Posidonia oceanica and the sea urchin Paracentrotus lividus through a short‐term series of controlled field and laboratory experiments after simulated or natural herbivory events. Of the five mechanisms tested, we found that three mechanisms – availability of alternative resources, increased predation rate and reduction in sea urchin numbers – effectively d ened herbivory and worked as potential buffering mechanisms. In contrast, plant compensatory growth and resistance did not show clear responses. While compensatory growth and plant resistance are direct plant mechanism to tolerate the effects of herbivory, the rest are indirect mechanisms that begin with a modification of a plant trait (i.e. canopy height) that influences other species preference and/or behaviour, which in turn influences plant consumption. These adaptive behaviours may be a crucial and often overlooked factor in the remarkable resilience that Mediterranean seagrass ecosystems show to herbivory.
Publisher: Springer Science and Business Media LLC
Date: 02-07-2015
Publisher: Inter-Research Science Center
Date: 19-01-2016
DOI: 10.3354/MEPS11531
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.MARPOLBUL.2017.10.036
Abstract: There is increasing uncertainty of how marine ecosystems will respond to rising temperatures. While studies have focused on the impacts of warming on in idual species, knowledge of how species interactions are likely to respond is scant. The strength of even simple two-species interactions is influenced by several interacting mechanisms, each potentially changing with temperature. We used controlled experiments to assess how plant-herbivore interactions respond to temperature for three structural dominant macrophytes in the Mediterranean and their principal sea urchin herbivore. Increasing temperature differentially influenced plant-specific growth, sea urchin growth and metabolism, consumption rates and herbivore preferences, but not movement behaviour. Evaluating these empirical observations against conceptual models of plant-herbivore performance, it appears likely that while the strength of herbivory may increase for the tested macroalga, for the two dominant seagrasses, the interaction strength may remain relatively unchanged or even weaken as temperatures rise. These results show a clear set of winners and losers in the warming Mediterranean as the complex factors driving species interactions change.
Publisher: Springer Science and Business Media LLC
Date: 19-10-2016
Publisher: Elsevier BV
Date: 07-2023
No related grants have been discovered for Timothy Smith.