ORCID Profile
0000-0002-1650-2617
Current Organisation
University of Tasmania
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Publisher: Inter-Research Science Center
Date: 23-04-2020
DOI: 10.3354/MEPS13295
Abstract: Anthropogenic drivers are flattening reef structure from 3-dimensional habitats composed of macroalgae and live branching corals towards low-profile turfing algae. Our current understanding of the consequences of widespread reef degradation currently fails to consider the responses of small mobile invertebrates (‘epifauna’) to patterns of change amongst reef structural elements (‘microhabitats’). Here, the taxonomic composition of 152 epifaunal assemblages was compared among 21 structurally erse benthic microhabitats across an Australian temperate to tropical climatic gradient, spanning 28.6 degrees in latitude from Tasmania to the northern Great Barrier Reef. Epifauna varied consistently with different microhabitat types, and to a much lesser extent with latitude. Macroalgae, live branching coral and turfing algae represented 3 extremes for epifaunal community structure, with most microhabitats possessing epifaunal assemblages intermediate between these endpoints. Amongst structural characteristics, epifauna related primarily to the degree of branching and hardness of microhabitats. Mobile invertebrate communities are likely to transform in predictable ways with the collapse of large erect macroalgae and live coral towards low-lying turf-associated communities.
Publisher: Wiley
Date: 11-04-2023
DOI: 10.1002/AQC.3944
Abstract: Quantification of species’ spatial distributions and population trends is crucial for successful conservation efforts. Obtaining sufficient population data, however, is often difficult in the marine environment, especially for rare fish and invertebrate species that are small, cryptic and very difficult to detect. This study sought to understand the effort required to search for undiscovered populations of small, cryptic, marine species in shallow vegetated coastal habitats and track population numbers, using the Critically Endangered red handfish ( Thymichthys politus ) as a representative species. A s ling strategy was designed using a combination of environmental DNA (eDNA) and structured underwater scuba surveys of life‐like 3D‐printed ‘handfish replicas’ to estimate detectability and ultimately determine whether current population monitoring is adequately covering the remaining habitat occupied by the species. Tested over scales of hundreds of metres to kilometres, the eDNA assays performed relatively poorly in situ , detecting red handfish presence in only ~13% of s les collected from the centre of a known, yet low‐density, red handfish site. In contrast, underwater searches for independently placed handfish replicas by scuba ers indicated that mean detection probabilities at finer scales (~100 m) ranged from 57 to 97%. Near certain (95% probability) detection of an adult handfish was achievable with only one to three surveys (300 m 2 belt transects), depending on the habitat complexity. While other species will vary in detectability using eDNA and underwater searches, these findings give insight into the general effort required for the detection of small, rare species inhabiting vegetated coastal environments. Such knowledge not only helps to refine monitoring and conservation efforts for known threatened species, but may also assist in identifying other inconspicuous species whose population declines may otherwise go unnoticed.
Publisher: Wiley
Date: 21-07-2021
DOI: 10.1111/ELE.13844
Abstract: Among the more widely accepted general hypotheses in ecology is that community relationships between abundance and body size follow a log‐linear size spectrum, from the smallest consumers to the largest predators (i.e. ‘bacteria to whales’). Nevertheless, most studies only investigate small subsets of this spectrum, and note that extreme size classes in survey data deviate from linear expectations. In this study, we fit size spectra to field data from 45 rocky and coral reef sites along a 28° latitudinal gradient, comprising in iduals from 0.125 mm to 2 m in body size. We found that 96% of the variation in abundance along this ‘extended’ size gradient was described by a single linear function across all sites. However, consistent ‘wobbles’ were also observed, with subtle peaks and troughs in abundance along the spectrum, which varied with sea temperature, as predicted by theory relating to trophic cascades.
Publisher: Public Library of Science (PLoS)
Date: 03-05-2018
Publisher: Authorea, Inc.
Date: 10-03-2021
DOI: 10.22541/AU.161536960.08128108/V1
Abstract: Amongst the more widely accepted general hypotheses in ecology is that community relationships between abundance and body size follow a log-linear size spectrum, from the smallest consumers to the largest predators (i.e., “bacteria to whales”). Nevertheless, most studies only investigate small subsets of this spectrum, due to extreme size classes that deviate from these linear expectations. In this study, we fit size spectra to field data from 45 rocky and coral reef sites along a 28° latitudinal gradient, and spanning 11 orders of magnitude in body size, from 3 μg to 150 kg. We found that 97% of the variation in abundance along this ‘extended’ size gradient was described by a single linear function across all sites. Moreover, consistent ‘wobbles’ were also observed, with subtle peaks and troughs in abundance along the spectrum, that related strongly to sea temperature and local site conditions.
Publisher: Wiley
Date: 17-12-2021
DOI: 10.1111/ELE.13661
Publisher: Elsevier BV
Date: 04-2022
Publisher: Wiley
Date: 04-2022
DOI: 10.1002/ECE3.8789
Abstract: Climate change and fisheries exploitation are dramatically changing the abundances, species composition, and size spectra of fish communities. We explore whether variation in ‘abundance size spectra’, a widely studied ecosystem feature, is influenced by a parameter theorized to govern the shape of size‐structured ecosystems—the relationship between the sizes of predators and their prey (predator–prey mass ratios, or PPMRs). PPMR estimates are lacking for avast number of fish species, including at the scale of trophic guilds. Using measurements of 8128 prey items in gut contents of 97 reef fish species, we established predator–prey mass ratios (PPMRs) for four major trophic guilds (piscivores, invertivores, planktivores, and herbivores) using linear mixed effects models. To assess the theoretical predictions that higher community‐level PPMRs leads to shallower size spectrum slopes, we compared observations of both ecosystem metrics for ~15,000 coastal reef sites distributed around Australia. PPMRs of in idual fishes were remarkably high (median ~71,000), with significant variation between different trophic guilds (~890 for piscivores ~83,000 for planktivores), and ~8700 for whole communities. Community‐level PPMRs were positively related to size spectrum slopes, broadly consistent with theory, however, this pattern was also influenced by the latitudinal temperature gradient. Tropical reefs showed a stronger relationship between community‐level PPMRs and community size spectrum slopes than temperate reefs. The extent that these patterns apply outside Australia and consequences for community structure and dynamics are key areas for future investigation.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Freddie J. Heather.