• Energy Research

Abstract Shifts in marine species distributions associated with climate change occur across large spatial areas and long time periods. Marine recreational fishing occurs in most countries with many participants interacting regularly with the environment, yet there have been few studies on the views of recreational fishers towards climate change. This study aims to assess perceptions of climate change for a boat-based recreational fishery in Western Australia, where fishing occurs across a wide latitudinal range, from tropical to temperate waters. Perceptions of climate change were assessed by fisher demographics and fishing behaviour. One in two respondents noticed changes in species types and distributions, with metropolitan residents and avid fishers more likely to notice these changes. Two out of three respondents considered climate change is occurring, recognition of which was higher amongst metropolitan residents, females, and younger respondents. Males and older respondents, on the other hand considered themselves to have more knowledge of climate change science. This study provides a baseline to assist in informing policy changes that might be required to address the impacts of climate change. Studies of this kind can also build support for citizen science programs to enhance data collection across the spatial and temporal time scales required to observe climate change.

Biodiversity indicators provide a vital window on the state of the planet, guiding policy development and management. The most widely adopted marine indicator is mean trophic level (MTL) from catches, intended to detect shifts from high-trophic-level predators to low-trophic-level invertebrates and plankton-feeders. This indicator underpins reported trends in human impacts, declining when predators collapse ("fishing down marine food webs") and when low-trophic-level fisheries expand ("fishing through marine food webs"). The assumption is that catch MTL measures changes in ecosystem MTL and biodiversity. Here we combine model predictions with global assessments of MTL from catches, trawl surveys and fisheries stock assessments and find that catch MTL does not reliably predict changes in marine ecosystems. Instead, catch MTL trends often diverge from ecosystem MTL trends obtained from surveys and assessments. In contrast to previous findings of rapid declines in catch MTL, we observe recent increases in catch, survey and assessment MTL. However, catches from most trophic levels are rising, which can intensify fishery collapses even when MTL trends are stable or increasing. To detect fishing impacts on marine biodiversity, we recommend greater efforts to measure true abundance trends for marine species, especially those most vulnerable to fishing.

Climate‐driven species redistribution is pervasive and accelerating, yet the complex mechanisms at play remain poorly understood. The implications of large‐scale species redistribution for natural systems and human societies have resulted in a large number of studies exploring the effects on individual species and ecological communities worldwide. Whilst many studies have investigated discrete components of species redistribution, the integration required for a more complete mechanistic understanding is lacking. In this paper, we provide a framework for synthesising approaches to more robustly understand and predict marine species redistributions. We conceptualise the stages and processes involved in climate‐driven species redistribution at increasing levels of biological organisation, and synthesize the laboratory, field and modelling approaches used to study redistribution related processes at individual, population and community levels. We then summarise links between scales of biological organisation and methodological approaches in a hierarchical framework that represents an integrated mechanistic assessment of climate‐driven species redistributions. In a rapidly expanding field of research, this framework provides direction for: 1) guiding future research, 2) highlighting key knowledge gaps, 3) fostering data exchange and collaboration between disciplines and 4) improving shared capacity to predict and therefore, inform the proactive management of climate impacts on natural systems.

Estuaries are particularly susceptible to climate change and drought resulting in atypical changes to freshwater flows. How such changes in flow impact on the ecology of estuarine fishes may depend on how a species moves in response to changing flow conditions. Acoustic telemetry was used to interpret fine-scale movements of two co-inhabiting estuarine fish species, black bream, Acanthopagrus butcheri and estuary perch, Macquaria colonorum in relation to freshwater flows, season and moon phase. We found black bream to be highly mobile, regularly travelling the length of the estuary and into the neighbouring estuaries. In contrast, estuary perch had particular home ranges and made occasional, upstream or downstream movements. Possibly influenced by freshwater flows, estuary perch moved at greater rates in the Tambo compared to fish in the Mitchell. Black bream resided in the upper estuary during winter and spring and the lower estuary during summer and autumn, whereas estuary perch remained in the upper estuary throughout the year, with occasional downstream movements in winter and spring. This study revealed 1) significantly large increases in freshwater flows result in mass downstream movements in both species, 2) fish moved upstream during full moons and 3) there are contrasting spatio-temporal patterns in movement between species. The results from this study highlight that estuarine fishes are likely to show differential sensitivity to the impacts of drought and climate change and illustrate how acoustic telemetry methods can be used to determine the environmental needs of fishes and help efforts to conserve and manage estuaries worldwide.

While governments and natural resource managers grapple with how to respond to climatic changes, many marine-dependent individuals, organisations and user-groups in fast-changing regions of the world are already adjusting their behaviour to accommodate these. However, we have little information on the nature of these autonomous adaptations that are being initiated by resource user-groups. The east coast of Tasmania, Australia, is one of the world's fastest warming marine regions with extensive climate-driven changes in biodiversity already observed. We present and compare examples of autonomous adaptations from marine users of the region to provide insights into factors that may have constrained or facilitated the available range of autonomous adaptation options and discuss potential interactions with governmental planned adaptations. We aim to support effective adaptation by identifying the suite of changes that marine users are making largely without government or management intervention, i.e. autonomous adaptations, to better understand these and their potential interactions with formal adaptation strategies.

AbstractSpecies distribution models are commonly used to determine a species’ probability of occurrence but have not been used to examine the effect of environmental habitat suitability on fish condition, which is considered to be an integrated measure of physiological status. Here, we test for a relationship between oceanographic habitat suitability and the body condition of kingfish (Seriola lalandi) from eastern Australia. We (a) test whether individuals sampled from areas of high‐quality habitat were in better condition than individuals sampled from areas of low‐quality habitat, and (b) assess whether the condition of kingfish responded to oceanographic habitat suitability predicted at varying time‐before‐capture periods. Kingfish habitat was modelled as a function of sea surface temperature, sea‐level anomaly and eddy kinetic energy in a generalized additive modelling framework. Model predictions were made over one‐ to six‐week time‐before‐capture periods and compared to field‐derived kingfish condition data measured using bioelectrical impedance analysis. Oceanographic habitat suitability was significantly correlated with kingfish condition at time‐before‐capture periods ranging from one to four weeks and became increasingly correlated at shorter lead‐times. Our results highlight that (a) fish condition can respond sensitively to environmental variability and this response can be detected using oceanographic habitat suitability models, and (b) climate change may drive extensions in species range limits through spatial shifts in oceanographic habitat quality that allow individuals to persist beyond historical range boundaries without their body condition being compromised.

AbstractThe environmental effects of climate change are predicted to cause distribution shifts in many marine taxa, yet data are often difficult to collect. Quantifying and monitoring species’ suitable environmental habitats is a pragmatic approach for assessing changes in species distributions but is underdeveloped for quantifying climate change induced range shifts in marine systems. Specifically, habitat predictions present opportunities for quantifying spatiotemporal distribution changes while accounting for sources of natural climate variation. Here we demonstrate the utility of a marine‐based habitat model parameterized using citizen science data and remotely sensed environmental covariates for quantifying shifts in oceanographic habitat suitability over 22 years for a coastal‐pelagic fish species in a climate change hotspot. Our analyses account for the effects of natural intra‐ and interannual climate variability to reveal rapid poleward shifts in core (94.4 km/decade) and poleward edge (108.8 km/decade) oceanographic habitats. Temporal persistence of suitable oceanographic habitat at high latitudes also increased by approximately 3 months over the study period. Our approach demonstrates how marine citizen science data can be used to quantify range shifts, but necessitates shifting focus from species distributions directly, to the distribution of species’ environmental habitat preferences.