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Context Australian mayflies are hypothesised to differ from those in the Northern Hemisphere by having longer, more variable emergence seasons that overlap more widely among taxa. Aim To test this hypothesis by comparing the behaviour of related northern and southern hemisphere species in similar habitats and at similar spatial scales. Methods Emergence dates were recorded fortnightly over two consecutive years, one ‘warm’ and one ‘cool’, in a rocky creek in south-eastern Tasmania, and at a coarser scale for Tasmania as whole, spanning an ∼20-year period. The results are compared with emergence patterns at two sites in the northern hemisphere climatically similar to Tasmania. Key results Durations of emergence seasons in Tasmania did not differ significantly at either the single site or whole of island scales from those in the northern hemisphere, but unlike in the latter, the start of emergence does not appear to be temperature-dependent. Conclusions Apparent regional differences are likely to result primarily from climatically inappropriate comparisons rather than from fundamental differences in behaviour. Implications Differences in the factor(s) that cue emergence suggest that the life histories of mayflies in Tasmania, and possibly elsewhere in Australia, are determined less by physiology than by aquatic ecology.

Lampreys are one of the few survivors of an ancient lineage of jawless vertebrates and have become an important study organism in numerous disciplines in the biological sciences, including evolutionary biology, embryology, ecology, physiology and biomedicine. At the same time, however, lampreys have created economic and ecological problems due, primarily, to the invasion of parasitic sea lamprey (Petromyzon marinus) into the North American Great Lakes and consequent negative impacts on local fish populations. Barriers, trapping and lampricide treatments have reduced these impacts, but concern for habitat restoration, non-target effects and possible evolution of resistance to lampricides suggests the need to develop additional strategies that supplement current control measures. The advent of functional genomics, and in particular CRISPR/Cas9 genome editing, offers a molecular approach to this on-going problem. Here, we review the successful application of functional genetic, transcriptomic, and CRISPR/Cas9 genome editing technologies in lampreys to address basic research questions in the fields of evolutionary and developmental biology. We then describe how these tools may be repurposed for use by fishery and conservation biologists to approach the problem of invasive sea lamprey from a molecular-genetic perspective.

Sometime between 2010 and 2012, Nile Tilapia (Oreochromis niloticus) invaded the remote Lake Kutubu, in the Southern Highlands of Papua New Guinea, apparently as a result of flooded aquaculture ponds. The subsequent burgeoning population of Tilapia has had apparent impacts on the RAMSAR-listed lakes’ ecology, but paradoxically may be benefiting endemic fish and crustaceans in the lake that have been under severe threat of extinction due to sustenance overfishing. Here, we explore options for eradicating or adaptively managing the invasive Tilapia population, and conclude that it is logistically and socially feasible to use low-risk genetic (chromosomal) technology to establish a non-self-sustaining population in the lake as an alternative protein source for local communities that causes minimal environmental damage while reducing exploitation rates on endemic taxa that have already driven at least three to apparent extinction.

For more than two decades the Great Lakes Fishery Commission has sought tactics to complement, and potentially replace, the use of barriers and lampricides to control sea lamprey (Petromyzon marinus) in the Great Lakes, but thus far without success. This paper examines the potential of modern genetic technology to suppress these invasive populations. We identified six recombinant options that appeared to be moderately to highly feasible, most of which were judged by an expert panel as extremely low or low risk, and for which research and development was broadly supported by stakeholders. The two options judged to overall best combine high efficacy and low risks were a Mendelian “sex ratio drive” and genetically modifying a prey species combined with killing or sterilizing sea lamprey that fed on it. Core issues regarding use of genetic biocontrol in the Great Lakes include technical problems associated with maintaining a sea lamprey brood line, information gaps for most options, the extent of broader public support, and the extent and nature of national and international consultation required in making decisions about control options.

Several factors, including: (1) on-going difficulties of cost-effectively managing invasive species; (2) recent successes in using recombinant genetics to suppress mosquito populations; and, (3) developments in gene-drive technology, have re-invigorated interest in using genetic biotechnology to manage the impacts of invasive species. However, the extent to which there is ‘social license’ to develop and use these technologies has not been widely canvassed. We surveyed stakeholders involved directly and indirectly in managing Sea Lamprey (Petromyzon marinus) in the upper North American Great Lakes and a key community group of resource users—recreational fishers—to assess their support and concerns about researching, developing, and potentially implementing recombinant methods that an expert group assessed as likely to be effective in managing Sea Lamprey in the Great Lakes. Both groups overwhelmingly supported initiating R&D and, if risks were deemed very low, undertaking steps towards implementation. The key concern expressed by both groups was the risk of impacts to non-target taxa, including valued native populations of Sea Lamprey outside of the Great Lakes. Few respondents expressed opposition based on ethical or moral grounds, which contrasts with previous surveys on the use of recombinant technology in general. The broad support for R&D into recombinant approaches is likely to reflect trust in the nominated implementing agency (the Great Lakes Fishery Commission), its history of extensive consultation prior to undertaking management actions, and the hope that genetic biocontrol could “solve” the Sea Lamprey problem rather than simply managing it.

The effects of invasive pathogens on wild fish and fish communities generally are not well documented. We compiled information on the impacts of mass mortality events due to Cyprinid Herpesvirus-3 (CyHV-3), otherwise known as Koi Herpesvirus, on wild North American populations of the invasive cyprinid, Cyprinus carpio (common carp), based on our personal experiences, discussions with North American fish ecologists and virologists, a detailed survey of technical and popular publications and a web search. We found evidence of 17 mass die-offs of carp due to CyHV-3 in North America since 2004, for 7 of which we were able to obtain information about carp before and after the events. For 6 of the events, effects of the die-offs on carp population indices appeared to be slight. Carp size-frequency distributions before and after the well-documented 2007/08 event in Ontario were also not conspicuously different. The exceptional event was at Blue Springs Lake, Missouri, in 2012, at which we estimate 65% of the carp present died as a result of CyHV-3 infections and carp abundance continues to decline. Why Blue Springs Lake differs from other events in North America is not clear. Overall, carp die-offs due to CyHV-3 in North America (1) confirm laboratory studies that only common carp are affected, (2) are of brief duration (3–6 weeks), (3) are not repeated in subsequent years and (4) cause much lower mortality (with the exception of Blue Springs Lake) than previously reported for carp in aquaculture facilities or in the laboratory. In terms of both wild carp and their effects on aquatic communities, the short and long-term effects of most die-offs appear to be slight. These features could have implications for the effectiveness of the proposed use of CyHV-3 to reduce feral carp populations in Australia.

We test for trace element proxies in the high-magnesium calcite fraction of bamboo coral internodes by comparing environmental conditions and growth rates to the specimen-mean compositions of 73 corals that were live-caught at depths ranging from 3 to 3950 m and collected from habitats ranging from tropical coral reefs to the Antarctic slope. Comparisons were done at a large geographic scale (LGS) and for a well sampled area south of Australia, across depths at a single site, in order to help separate the effects of environmental variables that co-vary at one spatial scale, but not the other. Thirty-seven trace elements were measured using solution-based Sector Field ICP-MS, of which seventeen were significantly detected in more than a third of the specimens. Only eight element/calcium ratios correlated significantly with any environmental variable at the large geographic scale, and only four did so at the local level. At the LGS, the highest correlation was between ambient temperature and Mg/Ca, which accounted for 89% of the variance across specimens, spanned all four Isidid sub-families and was independently significant in the two best sampled sub-families. The predictive (geometric mean) relationship is T ( ° C ) = - 23.9 ( ± 2.46 ) + 0.34 ( ± 0.25 ) Mg / Ca ( mmol / mol ) spanning a temperature range of −1.9 to 26.8 °C, Mg/Ca ratios from 58.6 to 155.1 mmol/mol, and an uncertainty (RMS) of 2.78 °C. The numbers in parentheses are 95% CIs. The slope of the regression does not differ significantly from that of abiotic high-Mg calcites, which suggests that the temperature-dependent incorporation of Mg into the carbonate results from kinetic reactions at the crystal surface. Analysis at the SH scale for the sub-set of specimens for which we had data suggests is also affected by growth rates. There were no obvious trace element correlates at either spatial scale of salinity or oxygen levels that could not be accounted for by covariance between these environmental parameters and, in most cases, temperature. Single and multiple correlation analyses also confirm previous suggestions that Ba/Ca in bamboo coral calcite is a proxy for seawater barium and hence refractory nutrients, suggest that Sr/Ca is influenced by specimen-mean Mg/Ca ratios and water temperature as well as possibly seawater Sr/Ca, and falsify for bamboo corals P/Ca (as well as P/Cd and Cd/Ca) as a proxy for seawater phosphate levels. The predictive relationship between Isidid skeletal-mean Ba/Ca and seawater silicate concentrations appears to be linear, and is given by silicate ( μ mol kg - 1 ) = - 56.7 ( ± 20.8 ) + 9217 ( ± 1632 ) Ba / Ca ( mmol / mol ) spanning a silicate range of 0.5 to 120 μmol kg−1, a Ba/Ca range of 0.0042 to 0.0195 mmol/mol, and with an uncertainty (RMS) of 33.1 μmol kg−1. Mn/Ca differences among specimens and sites are highly significant and appear to reflect seawater Mn, suggesting a proxy for this micronutrient. The compilation of growth rate data across 34 specimens indicates a wide range of growth rates even among con-familial specimens from within a single habitat, and suggests both ambient temperature and food availability underlie at least part of this variability.

We examine in detail δ 18 O and δ 13 C in the calcite internodes of bamboo corals as potential proxies of physiological and environmental variability, through (a) a “core top” calibration that includes specimens from a wide range of habitats and environmental conditions and (b) a comparison of high resolution serial point analyses along radial growth axes of a sub-set of specimens with each other, with instrumental temperature and salinity records, with growth rates and with a nominal skeletal proxy for temperature (Mg/Ca) in the same specimens. At the whole-of-specimen level, δ 18 O and the intercept of the strong within-specimen regression of δ 18 O against δ 13 C correlates highly with ambient temperatures at slopes that are identical to those reported for other marine biogenic carbonates (−0.22 per °C). δ 13 C varies predominantly with apparent specimen-mean growth rate. It also correlates with the slope of the within-specimen covariance between δ 18 O and δ 13 C, which in turn is distributed bi-modally among specimens and linked to differences in apparent growth rates. Within-specimens, variability in δ 13 C, and to a lesser extent δ 18 O, correlates between specimens collected in the same region and differs between regions, implying an environmental effect, but the factors involved for either isotope ratio are unclear. Correlations between δ 18 O and temperature (and Mg/Ca) range from positive to negative among specimens and appear to vary over time even within specimens. The mismatch between the consistent temperature-dependence of δ 18 O at the whole-of-specimen level and the mixed relationship within-specimens can be reconciled by assuming an unknown temperature-dependent factor affecting δ 18 O during the growth of Isidid calcite. The contrast between the results of the “core top” temperature calibration for δ 18 O, which are consistent with studies of other carbonates, and the apparently more complex suite of factors affecting both δ 13 C and δ 18 O within specimens strongly suggests that calibrations based on a “core top” approach be applied cautiously to environmental reconstructions based on variations of a nominal proxy within specimens.

Variability in the southwest (SW) Pacific Ocean circulation is influenced by the changes in the South Pacific subtropical gyre and its western boundary current, the East Australian Current (EAC). The EAC plays a significant role in transporting warm, well-ventilated, nutrient-poor waters to more temperate higher latitudes. Recent climate changes associated with EAC intensification have led to anomalous warming in the South Tasman, with implications for marine ecosystems and environment. A clear understanding of the significance of these changes requires knowledge of past natural variability. Here we have reconstructed a 4500 year record of regional sea surface radiocarbon reservoir ages (R) and local reservoir effects (ΔR). Our results reveal the centennial-scale variability over the last 4500 years, with R ranges as large as 390 14C yr. Older R (~410 14C yr) between 1610 to 1860 A.D. in our record, corresponding to the “Little Ice Age,” suggests a weaker influence of the EAC in the South Tasman. Between 4000 and 1900 cal years B.P., R and ΔR were significantly younger than the modern, with values of ~170 and −130 14C yr, respectively, indicating increased EAC transport of tropical waters into the South Tasman. We propose that the large R variability was influenced by strong and abrupt El Nino events which punctuated the muted El Nino–Southern Oscillation (ENSO) period in the mid-late Holocene and enabled increased westward flow of gyre waters into the SW Pacific. The strengthening of the EAC extension appears to have been a response to the precession-modulated ENSO-Southern Annular Mode interactions.

Fishing and climate change are profoundly impacting marine biota through unnatural selection and exposure to potentially stressful environmental conditions. Their effects, however, are often considered in isolation, and then only at the population level, despite there being great potential for synergistic selection on the individual. We explored how fishing and climate variability interact to affect an important driver of fishery productivity and population dynamics: individual growth rate. We projected that average growth rate would increase as waters warm, a harvest-induced release from density dependence would promote adult growth, and that fishing would increase the sensitivity of somatic growth to temperature. We measured growth increments from the otoliths of 400 purple wrasse (Notolabrius funicola), a site-attached temperate marine reef fish inhabiting an ocean warming hotspot. These were used to generate nearly two decades of annually resolved growth estimates from three populations spanning a period before and after the onset of commercial fishing. We used hierarchical models to partition variation in growth within and between individuals and populations, and attribute it to intrinsic (age, individual-specific) and extrinsic (local and regional climate, fishing) drivers. At the population scale, we detected predictable additive increases in average growth rate associated with warming and a release from density dependence. A fishing-warming synergy only became apparent at the individual scale where harvest resulted in the 50% reduction of thermal growth reaction norm diversity. This phenotypic change was primarily caused by the loss of larger individuals that showed a strong positive response to temperature change after the onset of size-selective harvesting. We speculate that the dramatic loss of individual-level biocomplexity is caused by either inadvertent fisheries selectivity based on behaviour, or the disruption of social hierarchies resulting from the selective harvesting of large, dominant and resource-rich individuals. Whatever the cause, the removal of individuals that display a positive growth response to temperature could substantially reduce species' capacity to adapt to climate change at temperatures well below those previously thought stressful.

Deep-sea coral reefs off southeast Australia are threatened by climate change and ocean acidification. An immediate priority to conserve these sensitive ecosystems would be the identification and protection of refugia areas.

Growth is a fundamental biological process, driven by a multitude of intrinsic (within-individual) and extrinsic (environmental) factors, that underpins individual fitness and population demographics. Focusing on the comprehensive information stored in aquatic and terrestrial organism hard parts, we develop a series of increasingly complex hierarchical models to explore spatial and temporal sources of growth variation, ranging in resolution from within individuals to across a species. We apply this modeling framework to an extensive data set of otolith increment measurements from tiger flathead (Platycephalus richardsoni), a demersal commercially exploited fish that inhabits the warming waters of southeast Australia. We recreated growth histories (biochronology) up to four decades in length from seven fishing areas spanning this species' range. The dominant pattern in annual growth was an age-dependent, allometric decline that varied among individuals, sexes, fishing areas, years, and cohorts. We found ev...

We use a novel proxy (growth rates of long-lived deep water fish, orange roughy) to reconstruct inferred water temperatures of intermediate water masses in both Northern and Southern Hemispheres since the mid-1800s. The data are consistent with instrumental records showing long-term warming in the Northern Hemisphere but also indicate decadal variability of intermediate depth temperatures that is coherent across the two hemispheres. This variability correlates with the dominant subpolar annular mode in each hemisphere and implies a bihemispheric oceanic response to external forcing that influences the properties of intermediate depth water masses.

Marine reservoir ages are a key element in calculating and constraining uncertainty in radiocarbon age estimates and are also essential to better understand regional ocean circulation. In this study, we present a new method to reconstruct long-term, high-resolution sea surface reservoir ages based on analysis of the organic skeleton of deep-sea (560 m) black coral (Anthozoa, Antipatharia). Our results confirm that antipatharians are extremely slow growing (typical radial growth rate for a South Pacific specimen around 0.03 mm/yr). Coupled uranium series and radiocarbon measurements were made on black coral collected live from the Norfolk Ridge (north Tasman Sea) to provide the first modern reservoir ages for this region. At the Norfolk Ridge, the average reservoir age between 1790 AD and 1900 AD was ∼330 years. This was followed by a steep decrease over time of about 70 years to 1950 AD (our most modern value). This indicates an increase in surface ocean ventilation of water masses in this region. These results are consistent with observational studies for the early twentieth century, which suggest significant changes in regional circulation of the southwest pacific.

Little is known about growth rates of deep-water reef-forming corals or the rates at which these reefs accumulate. Such information is critical for determining the resilience of the reefs to anthropogenic impacts such as trawling and climate change. We radiocarbon date live-caught and sub-fossil samples of the bioherm-forming coral Solenosmilia variabilis collected from precisely known depths and locations by means of a remotely operated vehicle on seamounts south of Tasmania, Australia. The growth rate of colonies live-caught between 958 and 1,454 m, which spans most of the depth range of the species locally, ranged from 0.84 to 1.25 mm linear extension yr−1 and tended to be higher in the deeper-caught material. Analysis of skeletal microstructure suggests annual deposition of growth increments near the growing tips, but not closer to the base, as the skeleton is extended and thickened. Dating of sub-fossil material indicates S. variabilis has been present on Tasmanian seamounts for at least the last 47,000 yrs and a reef accumulation rate of 0.27 mm yr−1.

This study tests the sensitivity of genetically based pest control options based on sex ratio distortion to intra- and intersexual aggressive interactions that affect male and female survival and fitness. Data on these interactions and their impacts were gathered for the mosquitofish Gambusia holbrooki (Poeciliidae), a promiscuous species with a strongly malebiased operational sex ratio and well-documented male harassment of females. The experimental design consisted of an orthogonal combination of two population densities and three sex ratios, ranging from strongly male-biased to strongly female-biased, and longterm observations of laboratory populations. Contrary to expectations, the number of males in a population had little evident effect on population demographics. Rather, the density of adult females determined population fecundity (as a result of a stock-recruitment relationship involving females, but not males), constrained male densities (apparently as a result of cannibalism or intersexual aggression), and regulated itself (most likely through effects of intrasexual aggression on female recruitment). The principal effect of males was to constrain their own densities via effects of male-male aggression on adult male mortality rates. Through use of a realistically parameterized genetic/demographic model, we show that of three different genetic options applied to control G. holbrooki, one based on recombinant sex ratio distortion (release of Female Lethal carriers) is marginally more efficient than a sterile male release program, and both outperform an option based on chromosomal sex ratio distortion (Trojan W). Nonlinear dependence of reproductive rate on female density reduces the efficacy of all three approaches. The major effect of intra- and intersexual aggression is mediated through females, whose interactions reduce female numbers and increase the efficacy of a control program based on sex ratio. Socially mediated male mortality has a small impact on control programs due to operational sex ratios that are heavily male-biased. The sensitivity of sex ratio-based control options to social factors will depend on the mating system of the targeted pest, but evidence of widespread density-dependent population regulation suggests that, for most species, the effects of elevated adult mortality (due to intra- and intersexual aggression) on control programs are likely to be slight. © 2013 by the Ecological Society of America.

During the past 40,000 years, global climate has moved into and out of a full glacial period, with the deglaciation marked by several millennial-scale rapid climate change events. Here we investigate the ecological response of deep-sea coral communities to both glaciation and these rapid climate change events. We find that the deep-sea coral populations of Desmophyllum dianthus in both the North Atlantic and the Tasmanian seamounts expand at times of rapid climate change. However, during the more stable Last Glacial Maximum, the coral population globally retreats to a more restricted depth range. Holocene populations show regional patterns that provide some insight into what causes these dramatic changes in population structure. The most important factors are likely responses to climatically driven changes in productivity, [O_2] and [CO_3^(2–)].

Genetic options for the control of invasive fishes were recently reviewed and synthesized at a 2010 international symposium, held in Minneapolis/St. Paul, MN, USA. The only option currently available “off-the-shelf” is triploidy, which can be used to produce sterile males for a release program analogous to those widely and successfully used for biological control of insect pests. However, the Trojan Y and several recombinant options that heritably distort pest population sex ratios are technologically feasible, are at or are close to proof-of-concept stage and are potentially much more effective than sterile male release programs. All genetic options at this stage require prolonged stocking programs to be effective, though gene drive systems are a potential for recombinant approaches. They are also likely to differ in their current degree of social acceptability, with chromosomal approaches (triploidy and Trojan Y) likely to be the most readily acceptable to the public and least likely to require changes in legislative or policy settings to be implemented. Modelling also suggests that the efficacy of any of these genetic techniques is enhanced by, and in turn non-additively enhance, conventional methods of pest fish control.

In Australia the European carp is widespread, environmentally damaging and difficult to control. Genetic control options are being developed for this species but risk-assessment studies to support these options have been limited. The key science challenge in this context is our limited understanding of complex and highly variable ecosystems. Hierarchical models are one way to approach this complexity and heterogeneity. These models treat the factors that determine risk as a joint probability distribution that can be factored into a series of simpler conditional distributions to allow Bayesian inference following observed outcomes. Designing a risk assessment around this approach, however, requires that the assessment endpoints (such as impacts on native species) are measurable, and that monitoring strategies are carefully designed and implemented in order that risk predictions are compared to outcomes. We therefore suggest that an evidence-based framework, supported by careful hazard analysis and quantitative risk assessment, and implemented within a stage-released protocol, is the safest way to move beyond the current emphasis on contained laboratory studies and qualitative risk assessments. We highlight impediments to this approach, and use the non-target impacts of daughterless carp in Australian billabongs as a case study to illustrate three methodological tools that not only provide solutions to some of these impediments but also encourage stakeholder participation in the risk assessment process.

Little is known about the demography of corals inhabiting deep-sea features due to the logistical difficulties of working at the extreme depths they inhabit. To obtain basic information about growth, mortality, and recruitment dynamics for such a coral, we applied modal analysis to the size frequency distributions of live-caught and sub-fossil specimens of the widely distributed solitary cup coral, Desmophyllum dianthus, collected on SW Pacific seamounts. Comparison of live-caught material collected in 1997 and 2007–2009 indicated modal progression over time and an implied maximum age of approximately 190 years, which is similar to ages determined previously for D. dianthus using radiometric techniques. A log-linear decline in the number of individuals with increasing size further implies a constant adult mortality rate, of 15.1% per annum in 1997 and 9.2% per annum in 2007–2009. The spacing of size modes in the 2007–2009 samples suggests regularly episodic recruitment events, at 22- to 32-year intervals, which may relate to periodic variability in large-scale Southern Ocean circulation. Preliminary analyses of size frequency distributions of the sub-fossil material suggest that the trophodynamics, growth, and adult mortality schedules of D. dianthus in the SW Pacific have remained basically similar throughout the Holocene.

Small temperature increases will benefit the growth of many cold-blooded animals, but laboratory studies indicate that warming can eventually exceed physiological limits, resulting in reduced growth. Evidence shows that this may have already happened for a fish species—the banded morwong—in the Tasman Sea. Climate change can affect organisms both directly, by affecting their physiology, growth, and behaviour1, and indirectly, for example through effects on ecosystem structure and function1,2. For ectotherms, or ‘cold-blooded’ animals, warming will directly affect their metabolism, with growth rates in temperate species predicted to increase initially as temperatures rise, but then decline as individuals struggle to maintain cardiac function and respiration in the face of increased metabolic demands3,4. We provide evidence consistent with this prediction for a marine fish (Cheilodactylus spectabilis) in the Tasman Sea; one of the most rapidly warming regions of the Southern Hemisphere ocean5. We estimated changes in the species’ growth rate over a 90-year period using otoliths—bony structures that fish use for orientation and detection of movement—and compared these changes to temperature trends across the species’ distribution. Increasing temperatures coincide with increased growth for populations in the middle of the species range, but with reduced growth for those at the warm northern edge of the species’ distribution, indicating that temperatures may have already reached levels associated with increased metabolic costs. If warming continues, the direct metabolic effects of increasing temperatures on this species may lead to declining productivity and range contraction.

We test for and calibrate a proxy for ocean temperature based on the skeletal composition of the widely distributed, deep-sea gorgonians in the family Isididae (bamboo corals), through use of three complementary methods: a short-term comparison of element/Ca ratios to a four-year temperature record, a long-term comparison with oceanographic records spanning forty years, and a geographic comparison of Isidids collected at sites ranging from the tropics to Antarctica. The assays consistently support a temperature-dependency for Mg/Ca ratios and suggest S/Ca is indirectly affected by temperature, but indicate little or no effect of temperature on P/Ca and Sr/Ca. The consensus relationship between Mg/Ca and temperature for Isidid calcite from the comparisons with the temperature time-series is T = −0.505 + 0.048 Mg/Ca, where T is in °C, Mg/Ca is in mmol/mol, and the applicable range is 3–6 °C. The results of the geographic assay, though imprecise, suggest the applicable range extends to temperatures below freezing. The scatter of data points around the regression of temperature and Mg/Ca is wide in all assays. This could reflect the effect of factors other than temperature on Mg/Ca ratios, but is also likely to reflect limitations of the field data, the effects of assumed constant growth rates in the corals and instrumental analytical error. The combined effects of micro-scale variability in growth rates and wide confidence intervals for each data point suggests that environmental reconstruction from Isidid internode calcite from sparse data or at time scales less than decades be done with caution. Comparisons within and among colonies do not indicate strong vital effects on ontogenetic variability in the corals, other than possibly close to the central pore of the coral. However, similar Mg/Ca ratios for Isidids from Antarctic and more temperate regions suggest adaptation to local conditions and hence a role for physiology at higher taxonomic levels, at least. Taxonomically higher level vital effects are also suggested by large differences between gorgonian families in their regressions between Mg/Ca and temperature, by Mg/Ca ratios that overlap over a wide temperature and habitat range, and for a non-linear relationship between temperature and the slope of the Mg/Ca-temperature relationship across the order.

Based on a series of correlations and the results of several experimental series on the territorial behavior of the threespot damselfish Eupomacentrus planifrons, a two-component system of the causation of territorial aggression is proposed. The first component, spatial commitment, determines the size of the area defended; the second, attack readiness, determines the vigor of such defense. The two differ in their responses to such factors as social isolation and repeated conspecific stimulation (and stimulation from non-related fishes). By their interaction, these two independent systems can account for not only many of the apparently contradictory results reported in the literature concerning the causation of aggressive behavior (such as the effects of social isolation), but also the stability of social systems based on territoriality. Forms of territorial advertisement, such as bird song and poster-coloration, are considered in terms of this two-component system.

Little is known about the factors that affect the growth rates of deep-water corals. Analysis of 23 specimens of bamboo corals, a ubiquitous deep-water group, that were reliably aged using radiometric techniques or validated increment counts indicates that the radial growth rate of the coral's calcite internode declines with depth and increases logistically with ambient temperature. Temperature alone accounts for about half of the variance among specimens in lifetime mean growth rates. Growth rates plateau below 2°C and above 5°C, which likely reflects physiological constraints on growth and calcification. Thus far, the only other effect on growth rate identified is a tendency for colonies from the NE Pacific to grow faster relative to ambient temperature than colonies in other regions. Analysis of elemental composition of the calcite internode, based on data available for 16 of the 23 specimens, shows that, contrary to suggestions in the literature, growth rate does not correlate with Sr/Ca ratios, neither among or within colonies. Rather, within-colony ontogenetic variability in increment width, an index of short-term growth rate, correlates positively with calcium weight-frac- tions and negatively with the ratio between P and S, an index of organic content. The underlying mechanism is likely to be a link between crystal ultrastructure, which varies with growth rate, and the ratio between CaCO3 and organic matrix in different crystal types. Between colonies, composi- tion correlates poorly with growth rate. This could reflect spatial and temporal heterogeneity in other environmental factors that determine internode composition, as well as difficulties in standardising P measurements across specimens.

Bamboo corals (Family Isididae) are an important component of seamount benthos south of Tasmania. Besides having lifespans of up to 400 yr, little is known about their basic ecology, nor how to decode potential climate signals encoded in their skeletons. We explored the stable nitrogen isotope and radiocarbon compositions of the skeletal organic fraction of the genera Isidella, Keratoisis and Lepidisis collected from 3 Tasmanian seamounts. Analyses were performed on tissues and organic node growth rings sampled at a temporal resolution of 1 to 4 yr. Radiocarbon chronologies exhibited nuclear bomb signals characteristic of surface waters and constrained radial growth rates to ~35 ± 10 µm yr–1 for 3 specimens of the genus Lepidisis and 113 ± 17 µm yr–1 for 1 specimen of Isidella. δ15N values of the living tissue and underlying gorgonin were similar and averaged 9 to 12‰. Records of δ15N from 8 different specimens showed subtle, quasi-decadal patterns over the last ~100 yr, although the amplitude of these features (~1‰) was similar to the average intra- and intercolony reproducibility. These results demonstrate the utility of deep-sea corals to track seamount biogeochemical processes over long time scales, and suggest that the extent of nutrient depletion of surface waters and associated trophic dynamics have remained relatively constant in this region over centuries. This provides an important baseline for the evaluation of the impacts of anthropogenic climate change.

Proposals to farm non-native and genetically modified species are often highly contentious because there is no reliable method of ensuring that they do not escape, reproduce and become environmental problems. Suggested approaches to prevent breeding outside hatcheries are unable to guarantee sterility in both sexes or cannot easily be applied to animals. We developed and tested on two contentious groups — fish and oysters — genetic constructs that render the animals functionally sterile outside of hatchery conditions, but allow normal development in captivity following brief provision of a repressor compound at a particular life history stage. “Sterile Feral” constructs consist of a stage-specific promoter, a blocker for a critical developmental gene and a repressible element. In transient assays, prototype constructs worked as expected, causing high mortality under non-repressed conditions in both fish and molluscs, and lower mortality, often equal to controls, in the presence of the repressible element (doxycycline). Sterile feral technology can potentially be applied to a wide range of species and be designed to use multiple, independent sterilizing constructs, minimizing the risk of establishing feral populations. Full tests of efficiency, however, require trials in integrated lines, currently in progress, and the usefulness of the technology could depend on the development of an improved repressible element.

We test two hypotheses, that annual environmental cycles produce periodic variability in the skeletal composition of deep-water gorgonians, and that these cycles can be counted to determine the coral's age. Annual periodicity of deposition was tested by comparing the internode composition of bamboo corals live-collected 10 years apart in the Southern Ocean. The validity of the comparison was substantiated by growth rates for the 10-year interval (77–121 μm/yr) that were confirmed by radiocarbon analysis. Variability in Mg/Ca and possibly S/Ca, but not Sr/Ca or P/Ca, was consistent with annual cycles of deposition. However, spectral analysis of Mg/Ca data for a larger coral showed little or no spectral peak associated with an annual cycle of deposition (though there were peaks at periods of 4–5 and 11–15 years). The absence of an annual peak is likely to reflect growth rates that vary over time, coral cross-sections that change shape over time, and interannual differences in the seasonal range of environmental variability. The resulting subjectivity in what defines an annulus, along with evidence that the nature and extent of annual periodicity differs among sites, means that the technique is likely to be inherently imprecise and to require independent validation for each site and taxon before it can be applied.

Recombinant genetic technology offers considerable potential for the safe, cost-effective control of invasive fish. This article reviews the range of genetic approaches suggested for controlling invasive species, and considers their practicality, likely efficacy, and the risks they entail. Implementation of any genetic method to control invasive fish will be heavily influenced by an as yet unknown level of public acceptability and a regulatory and policy framework for managing environmental applications of genetic technology that is confused at almost all jurisdictional levels.

We examined site differences in the elemental composition of the primordium and ontogenetic variability of Sr in otoliths of fish from Australia and New Zealand and, as an out-group, the North Atlantic. Differences among sites in primordium composition are slight, but significant for all five elements assayed (Sr, Pb, Cu, Zn and Hg), but principally reflect differences between the North Atlantic and SW Pacific specimens, do not replicate for independent samples in the SW Pacific and constitute a poor “natural tag” in roughy, with

The oceanographic consequences of climate change are increasingly well documented, but the biological impacts of this change on marine species much less so, in large part because of few long-term data sets. Using otolith analysis, we reconstructed historical changes in annual growth rates for the juveniles of eight long-lived fish species in the southwest Pacific, from as early as 1861. Six of the eight species show significant changes in growth rates during the last century, with the pattern differing systematically with depth. Increasing temperatures near the ocean surface correlate with increasing growth rates by species found in depths 1,000 m) species have declined substantially during the last century, which correlates with evidence of long-term cooling at these depths. The observations suggest that global climate change has enhanced some elements of productivity of the shallow-water stocks but also has reduced the productivity, and possibly the resilience, of the already slow-growing deep-water species.

Nucleotide sequence data of the mitochondrial cytochrome oxidase I (COI) gene, were compared among 17 specimens of Sacculina carcini parasitising three portunid hosts as a preliminary assessment of haplotype structure in a poorly understood species for which there are few morphological characters on which to base taxonomic analysis. S. carcini parasitising Carcinus maenas (from Sweden, England and Denmark) were compared with S. carcini parasitising Liocarcinus marmoreus (from Ireland) and Liocarcinus holsatus (from Wales). Specimens of three congeneric sacculinid species and one confamilial species were included in the comparison as outgroups. The comparison confirmed that specimens of S. carcini from different hosts and different regions are all the same species. The data also suggested geographically consistent sequence differences among sampled sites, high levels of similarity within sites and very large differences between species, all of which suggests that analysis of the COI gene sequence could be a useful method for resolving population genetics and taxonomy of rhizocephalans.

Marine biological invasions are increasingly recognised as a threat to biodiversity and coastal industry, including fisheries. Globally, efforts are underway to contain, if not eradicate, several high-impact marine invasive species. However, working in a marine environment places unique social, political and technical constraints on options for pest control, which we explored in a series of stakeholder workshops. Results suggest that current efforts are low risk and publicly acceptable, but have a low probability of success against established invaders. However, techniques deemed likely to be successful and ultimately needed in a marine context are currently more contentious for social and political reasons. To control introduced marine pests, scientists and managers will need to overcome perceptual biases among marine stakeholders, develop a decision-making framework for what is perceived to be an open system, and focus on technologies likely to be both effective and publicly and politically acceptable.

Port Phillip Bay (PPB) is a large (1,930 km2), temperate embayment in southern Victoria, Australia. Extensive bay-wide surveys of PPB have occurred since 1840. In 1995/1996 the Commonwealth Scientific and Industrial Research Organization (CSIRO) Centre for Research on Introduced Marine Pests (CRIMP) undertook an intensive evaluation of the region with the aims of developing a comprehensive species list of native and introduced biota and contrasting previous bay-wide assessments with a current field survey in order to detect new incursions and discern alterations to native communities. Two methods were used to meet these aims: a re-evaluation of regional museum collections and published research in PPB to identify and determine the timing of introductions; and field surveys for benthic (infauna, epifauna and encrusting) organisms between September 1995 to March 1996. One hundred and sixty introduced (99) and cryptogenic (61) species were identified representing over 13% of the recorded species of PPB. As expected, the majority of these are concentrated around the shipping ports of Geelong and Melbourne. Invasions within PPB appear to be increasing, possibly due to an increase in modern shipping traffic and an increase in aquaculture (historically associated with incidental introductions); however the records of extensive biological surveys suggest that this may, in part, be an artefact of sampling effort. In contrast to Northern Hemisphere studies, PPB (and Southern Hemisphere introductions in general) have significantly different suites of successfully invading taxa. PPB is presented as one of the most invaded marine ecosystems in the Southern Hemisphere.

In Australia and most other invaded locations, rates of range expansion by the European shore crab, Carcinus maenas, are typically only a few kilometres per year, despite a planktonic duration upwards of 50 days and off-shore larval development. This relatively static distribution is punctuated by rare episodes of long-distance and large-scale spread, some of which appear to be related to unusual oceanographic conditions and some of which are likely to be human assisted. These observations suggest, first, that long planktonic duration and off-shore development in a marine invertebrate does not preclude very localised recruitment, and, second, that this recruitment norm may be punctuated by brief episodes of wide scale mixing of propagules. Punctuated dispersal has previously been suggested to account for large-scale biogeographic patterns of distribution and speciation, but may also have implications for the processes that stabilise structured spatial metapopulations.

Atmospheric circulation in the southern mid-latitudes is dominated by strong circum-Antarctic zonal west winds (ZWW) over the latitude range of 35 to 60°S. These winds exhibit coherent seasonal and interannual variability, which has been related both to Antarctic (e.g. polar ice) and low-latitude climate (e.g. El Nino–southern oscillation) parameters. Historical and recent studies suggest that, at its northern margins, variability in the ZWW also has a marked quasi-decadal component. Analysis of sea-level pressure and rainfall data for the Australian region, South Africa and South America confirms frequent indications of quasi-decadal variability in parameters associated with the ZWW, which appears to be in phase around the hemisphere. This variation broadly correlates with the sunspot cycle, and specifically appears to reflect sunspot-correlated, seasonally modulated shifts in the latitude range each year of the sub-tropical ridge over eastern Australia. Sunspot-correlated variability in the southern mid-latitudes is likely to have substantial effects on temperate climate and ecology and is consistent with recent models of solar effects on upper atmospheric climate, though the mechanisms that link these to winds and rainfall at sea level remain obscure. Copyright © 2002 Royal Meteorological Society

The elemental composition of otoliths is increasingly being examined as a means of resolving the fine scale stock and population structure of fishes. The technique has been applied to three sets of problems: (1) discriminating between marine and freshwater populations (or life history stages), (2) determining links between natal rivers or nursery areas and adult stocks, and (3) assessing population structure in marine fishes. Thus far, there are few consistent patterns in the data. Diagnostic elements differ between species and systems; experimental and correlative studies provide little support for strong environmental effects on otolith composition (other than effects of extreme differences in salinity/strontium concentrations); and the physiological mechanisms that would allow such an effect for most elements are not well documented. The area of investigation suffers from: a lack of well-established benchmark studies against which ‘reality’ of results can be assessed; small sample sizes and incomplete analysis; and non-critical evaluation of results. Two areas of research look promising: the use of marked differences between marine and freshwater fishes (or the corresponding portions of otoliths of anadromous fish) in strontium concentrations to track migrating coastal fishes, and apparently robust indications of regional structuring of some marine fish populations. The relative youthfulness of the field dictates the need for work in a number of areas, but priorities at this stage should include developing a better understanding of the physiological mechanisms that determine otolith composition and its variability, including distinguishing the effects of handling and contamination from ‘real’ composition, and validating apparent patterns of stock structure both by independent replication of results and comparisons against other sources of information, such as genetic and tagging studies. To assure data quality and form a base for corroboration of results, widespread use of certified reference materials and careful documentation of analytic procedures are essential.

Exotic marine species are a threat to the biodiversity and health of Australian coastal marine ecosystems and to the industries and amenities that depend on them. Although the issue of introduced marine species has a long history world wide, the magnitude of the threat they pose to Australia has only become apparent since the mid-1980s. Recent surveys show that there are over 250 introduced marine species in Australian waters. They range from plankton and algae to fishes, occur in every port thus far examined, and have invaded habitats as diverse as intertidal rock pools to the open oceanic shelf. In many areas, exotic species now dominate marine communities. Most of these invaders are ecological pollutants rather than disasters, but several are having major impacts on Australia's marine ecosystems. There are few options currently available to deal with these invaders. Two complementary approaches are needed. First, we need to slow the rate of invasion by appropriate management of shipping, mariculture an...

The use of otolith chemistry as a tool for analysing the biology of fishes assumes that the procedures used to collect and prepare otoliths for analysis do not alter their composition. With otoliths of Nemadactylus macropterus, Hoplostethus atlanticus, and Rhombosolea tapirina, we show that this assumption is not valid for the elements that can be detected using electron-probe microanalysers (those present at concentrations greater than ≃100 parts per million): all six elements routinely measured using these techniques were affected by at least one post-mortem procedure tested. Measured concentrations of calcium and strontium were relatively insensitive to most procedures tested, whereas concentrations of sodium, potassium, sulphur and chlorine were affected substantially by many commonly used procedures. The ease with which otolith composition could be modified post-mortem suggests that apparent geographic, habitat-specific or ontogenetic differences in otolith composition should be interpreted with extreme caution because of easily induced artefacts and the problem of pseudo-replication associated with the ways otoliths are sampled and prepared for analysis.

Analysis of the chemistry of calcified tissues has been suggested to be a source of useful information on the population structure and environmental history of fishes. We have investigated this approach as a means of determining the number of spawning areas and diversity of migration routes in the large pelagic scombrid, Thunnus maccoyii (southern bluefin tuna). Analysis was based on ontogenetic variation in the composition of sagittal otoliths, as measured using two probe microanalysers (wavelength dispersive electron probe microanalysis and proton-induced X-ray emission microanalysis), of 9 larvae collected on the single known spawning ground (NE Indian Ocean), of 29 juveniles caught at different points along the known migration routes (off western Australia, southern Australia, and South Africa), and of 14 adults caught in the high-seas fishery (off SE Australia). Fifteen elements were detected in T. maccoyii sagittae, but only six (Ca, Na, Sr, K, S, and Cl) were consistently present at concentrations above minimum detection limits. No attempt was made to measure the concentrations of C, N and O, which are assumed to also be present. Comparisons among different samples indicated that: (1) variation in the composition of the otolith primordium was unimodal and, generally, normally distributed; (2) this composition varied among specimens as a function of their size or, apparently, year-class; (3) individuals collected from widely separated locations did not differ clearly in the composition of the most recently deposited sections of their otoliths; and (4) all variation in the composition of adult otoliths was encompassed in the range of variation of juveniles collected along the major known migration route. These observations are consistent with the hypothesis of a single spawning area for T. maccoyii, but also indicate that the range of environmentally correlated variation in composition is too low to provide a robust test of the diversity of migration routes. It is not clear why this variation is so low, but we suspect that it reflects both the relative homogeneity of the pelagic environment and a weak effect of environmental factors on the concentration of elements present in otoliths at levels≳1 ppm.

Ocean acidification has been predicted to reduce the ability of marine organisms to produce carbonate skeletons, threatening their long-term viability and severely impacting marine ecosystems. Corals, as ecosystem engineers, have been identified as particularly vulnerable and important. To determine the sensitivity of corals and allied taxa to long-term exposure to very low carbonate concentrations, we examined the distribution and skeletal characteristics of coral taxa along a natural deep-sea concentration gradient on seamounts of SW Australia. Carbonate under-saturation had little evident effect on the depth distribution, growth or skeletal composition of live scleractinians or gorgonians, with corals growing, often abundantly, in waters as much as 20 to 30% under-saturated. Developmental anomalies in the deepest skeleton-forming anthozoan collected (an isidid gorgonian, at nearly 4 km depth) suggest an absolute low tolerance limit of about 40% under-saturation. Evidence for an effect of acidification on the accumulation of reef structure is ambiguous, with clear indications of dissolution of high-magnesium calcite (HMC) gorgonian skeletons at depths below 2300 m, but also abundant, old scleractinian skeletons well below the aragonite saturation horizon. The latter might be the result of ferromanganese deposition on exposed skeletons, which, however, may render them inhospitable for benthic organisms.

We describe a previously unknown assemblage of seamount-associated megabenthos that has by far the highest peak biomass reported in the deep-sea outside of vent communities. The assemblage was found at depths of 2–2.5 km on rocky geomorphic features off the southeast coast of Australia, in an area near the Sub-Antarctic Zone characterised by high rates of surface productivity and carbon export to the deep-ocean. These conditions, and the taxa in the assemblage, are widely distributed around the Southern mid-latitudes, suggesting the high-biomass assemblage is also likely to be widespread. The role of this assemblage in regional ecosystem and carbon dynamics and its sensitivities to anthropogenic impacts are unknown. The discovery highlights the lack of information on deep-sea biota worldwide and the potential for unanticipated impacts of deep-sea exploitation.

The deleterious effects of tributyltin (TBT) on spermiation in fish have been attributed to its role in inhibiting aromatisation of androgens to estrogens, and the critical role of the latter in sperm development. We test this hypothesis by examining sperm parameters, fertilisation and hatching success in males of two fish species exposed throughout life to doses of Fadrozole, a non-steroidal aromatase inhibitor (AI), provided in their diets. AI-treatment caused 100% male development in zebrafish, but only partial masculinisation in medaka, in both cases supporting previous studies and suggesting different roles of estrogen in sexual differentiation in the two species. Milt volume, initial sperm motility, maximum sperm swimming duration and sperm morphology did not differ significantly between Control and AI-dosed fish in either species, after excluding low milt volumes in sex-changed females in medaka. Fertilisation rates were also unaffected by the aromatase inhibition, but hatching success in medaka was 31% lower than in Control males, suggesting a previously unreported effect of aromatase on sperm quality. The slight effect of aromatase inhibition on sperm parameters in general contrasts with the marked effect of TBT on fish sperm, and suggests that a mechanism other than depressed estrogen levels is involved.

Electron probe microanalyzers fitted with energy-dispersive (ED) and wavelength-dispersive (WD) X-ray spectrometers are the standard instruments for measuring microscale differences in the chemical composition of the calcified tissues of fishes. We review the principles of using these spectrometers, detail procedures for preparing otoliths for microanalysis, and compare the accuracy and sensitivity of the two instruments. ED systems on electron probes are prone to produce spectral artifacts, peak overlaps and difficulties in modelling nonlinear backgrounds. Current generation ED systems do not, therefore, appear suitable for quantitative analysis of trace elements ( 3μW · μm−2 resulted in unacceptable levels of specimen damage.

Micro-PIXE has been used to measure the trace element distribution in otoliths from several species of ocean fish, in order to investigate its possible use in stock discrimination. Trace elements detected include Sr, Fe, Mn, Ni, Zn, Cu, Se, Cd, Br, Hg and Pb. Trace elements Na, K, Cl, S and Cl were detected with the electron microprobe. The high sensitivity of PIXE demands a meticulous sample preparation procedure to avoid contamination problems. Practical problems associated with the application of the technique were investigated in detail. Preliminary results indicate that most trace elements except Sr, are present at close to the limits of detection at few ppm, but biologically significant data can be obtained for stock discrimination applications.

Viviparity is reported in twelve species of the family Clinidae in Tasmanian waters, and superfoetation (the simultaneous development of multiple batches of eggs and/or embryos) in nine of the twelve (all in the subfamily Clinini). The reproductive anatomy and life history features are documented in two superfoetate, shallow-water species,Heteroclinus perspicillatus andHeteroclinus sp. nov. (Scott's Weedfish). Gestation of embryos is intrafollicular and their mode of nutrition shifts from lecithotrophy during early development to trophodermal matrotrophy and, eventually, intestinal nutrient transfer. The sizes of the newly born larvae differ between species, but in all cases maternal investment in individual offspring (as measured by the proportionate increase in embryo dry weight)—20125%, 5744% and 3140% forH. perspicillatus, Scott's Weedfish andH. heptaeolus, respectively — is among the highest recorded for teleosts. Relative fecundity, however, is comparable to those of temperate, demersal spawning blennioids, and this suggests that high levels of maternal investment and relatively advanced stages of larval development at parturition for the sub-family as a whole do not involve a cost in individual fecundity. Parturition, which occurs over several months in spring and summer, is asynchronous. After parturition, the larva spend from 3 to 7 weeks in the plankton, primarily in in-shore waters. Post-settlement growth is rapid and most of the reproductive populations consist of fishes in the 1 + year-class.

Nature Clim. Change 5, 635–639 (2015); published online 24 June 2015; corrected after print 24 June 2015. In the print version of this Perspective, in the third sentence of the last paragraph of the main text, the quote is incorrectly attributed, and the sentence should have read: As frankly stated to us by a member of an agency concerned with the impacts of climate change on Australia generally, “why should the government or public invest in protecting a community that few people know or care about?”.

Chemical analysis of deepwater octocorals collected at 1000 m depth off southern Australia indicates long-term cooling, beginning in the mid-18th century. This cooling appears to reflect shoaling of isotherms along the continental shelf, that can be related statistically, observationally and by modeling to increasing coastal sea-surface temperatures, that in turn reflect a poleward extension of the SW Pacific boundary current (the East Australian Current). The oceanographic changes implied by the coral record suggest climate change in temperate Australia starting about the time of European settlement. Correlations between temperate Australian and Antarctic indices suggest these long-term changes might also be relevant to Antarctic climate.

Assemblages of megabenthos are structured in seven depth-related zones between ~700 and 4000 m on the rocky and topographically complex continental margin south of Tasmania, southeastern Australia. These patterns emerge from analysis of imagery and specimen collections taken from a suite of surveys using photographic and in situ sampling by epibenthic sleds, towed video cameras, an autonomous underwater vehicle and a remotely operated vehicle (ROV). Seamount peaks in shallow zones had relatively low biomass and low diversity assemblages, which may be in part natural and in part due to effects of bottom trawl fishing. Species richness was highest at intermediate depths (1000–1300 m) as a result of an extensive coral reef community based on the bioherm-forming scleractinian Solenosmilia variabilis. However, megabenthos abundance peaked in a deeper, low diversity assemblage at 2000–2500 m. The S. variabilis reef and the deep biomass zone were separated by an extensive dead, sub-fossil S. variabilis reef and a relatively low biomass stratum on volcanic rock roughly coincident with the oxygen minimum layer. Below 2400 m, megabenthos was increasingly sparse, though punctuated by occasional small pockets of relatively high diversity and biomass. Nonetheless, megabenthic organisms were observed in the vast majority of photographs on all seabed habitats and to the maximum depths observed - a sandy plain below 3950 m. Taxonomic studies in progress suggest that the observed depth zonation is based in part on changing species mixes with depth, but also an underlying commonality to much of the seamount and rocky substrate biota across all depths. Although the mechanisms supporting the extraordinarily high biomass in 2000–2500 m depths remains obscure, plausible explanations include equatorwards lateral transport of polar production and/or a response to depth-stratified oxygen availability.