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Invertebrate Biology
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The aim of this study was to assess how individual size-at-hatching and food consumption influences the growth of Octopus pallidus hatchlings reared under simulated seasonal temperature regimes in Tasmania.
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A novel method was used to investigate the population structure and dispersal patterns of Octopus maorum, an octopus species with a planktonic larval stage, which forms a distinct and large aggregation in southeast Tasmania. Single and multi-elemental signatures within the ‘early life history’ region of the stylet (an internal ‘shell’) were used to determine levels of connectivity and the common origins of individuals collected from 5 locations across Tasmania, South Australia and New Zealand.
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By utilising targeted microprobe technology, the analysis of elements incorporated within the hard bio-mineralised structures of marine organisms has provided unique insights into the population biology of many species. As hard structures grow, elements from surrounding waters are incorporated effectively providing a natural ‘tag’ that is often unique to the animal’s particular location or habitat. The spatial distribution of elements within octopus stylets was investigated, using the nuclear microprobe, to assess their potential for determining dispersal and population structure in octopus populations. This was investigated in adult Octopus pallidus sourced from a commercial fishery in Tasmania.
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Five polymorphic microsatellite loci were developed and then used to assess the population genetic structure of a commercially harvested merobenthic octopus species (Octopus maorum) in south-east Australian and New Zealand (NZ) waters. Beak and stylet morphometrics were also used to assess population differentiation in conjunction with the genetic data.
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Robust prediction of population responses to changing environments requires the integration of factors controlling population dynamics with processes affecting distribution. This is true everywhere but especially in polar pelagic environments. Biological cycles for many polar species are synchronised to extreme seasonality, while their distributions may be influenced by both the prevailing oceanic circulation and sea-ice distribution. Antarctic krill (𝘌𝘶𝘱𝘩𝘢𝘶𝘴𝘪𝘢 𝘴𝘶𝘱𝘦𝘳𝘣𝘢) is one such species exhibiting a complex life history that is finely tuned to the extreme seasonality of the Southern Ocean. Dependencies on the timing of optimal seasonal conditions has led to concerns over the effects of future climate on krill’s population status, particularly given the species’ important role within Southern Ocean ecosystems. Under a changing climate, established correlations between environment and species may breakdown. Developing the capacity for predicting krill responses to climate change therefore requires methods that can explicitly consider the interplay between life history, biological conditions, and transport. The Spatial Ecosystem And Population Dynamics Model (SEAPODYM) is one such framework that integrates population and general circulation modelling to simulate the spatial dynamics of key organisms. Here, we describe a modification to SEAPODYM, creating a novel model – KRILLPODYM – that generates spatially resolved estimates of krill biomass and demographics. This new model consists of three major components: (1) an age-structured population consisting of five key life stages, each with multiple age classes, which undergo age-dependent growth and mortality, (2) six key habitats that mediate the production of larvae and life stage survival, and (3) spatial dynamics driven by both the underlying circulation of ocean currents and advection of sea-ice. Here we present the first results of KRILLPODYM, using published deterministic functions of population processes and habitat suitability rules. Initialising from a non-informative uniform density across the Southern Ocean our model independently develops a circumpolar population distribution of krill that approximates observations. The model framework lends itself to applied experiments aimed at resolving key population parameters, life-stage specific habitat requirements, and dominant transport regimes, ultimately informing sustainable fishery management. ____ This dataset represents KRILLPODYM modelled estimates of Antarctic krill circumpolar biomass distribution for the final year of a 12-year spin up. Biomass distributions are given for each of the five key life stages outlined above. The accompanying background, model framework and initialisation description can be found in the following reference paper: 𝗚𝗿𝗲𝗲𝗻 𝗗𝗕, 𝗧𝗶𝘁𝗮𝘂𝗱 𝗢, 𝗕𝗲𝘀𝘁𝗹𝗲𝘆 𝗦, 𝗖𝗼𝗿𝗻𝗲𝘆 𝗦𝗣, 𝗛𝗶𝗻𝗱𝗲𝗹𝗹 𝗠𝗔, 𝗧𝗿𝗲𝗯𝗶𝗹𝗰𝗼 𝗥, 𝗖𝗼𝗻𝗰𝗵𝗼𝗻 𝗔, & 𝗟𝗲𝗵𝗼𝗱𝗲𝘆 𝗣. (2023) KRILLPODYM: a mechanistic, spatially resolved model of Antarctic krill distribution and abundance. 𝘍𝘳𝘰𝘯𝘵𝘪𝘦𝘳𝘴 𝘪𝘯 𝘔𝘢𝘳𝘪𝘯𝘦 𝘚𝘤𝘪𝘦𝘯𝘤𝘦, 10 Article 1218003. https://doi.org/10.3389/fmars.2023.1218003
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The data was collected from 2 years of field sampling from the commerical octopus (Octopus pallidus) fishery in NW Tasmania in Bass Strait. The data consists of morphological, reproductive and ageing information.