Modelling the advection of vertically migrating shrimp larvae

The role of larval advection in determining the complex, large-scale patterns of immigration of penaeid postlarvae in the Gulf of Carpentaria is investigated by modelling the interaction between diurnal vertical migration of larvae with wind-forced and tidal currents. Eight vertical migration schemes are modelled in which both the timing of the migration and the position of the larvae in the water column are varied. These schemes are then coupled with both two-dimensional and three-dimensional models of the currents of the Gulf, to examine horizontal advection of larvae. When the larvae migrate vertically with a diurnal period, their horizontal advection is enhanced. The largest horizontal advection distances occur when the larvae move diurnally from the water column into the bottom boundary layer. Advection distances of up to 165 km are possible during the two to three week planktonic larval period. This distance corresponds to, and may determine, the offshore extent of the adult distribution. The onshore advection pattern of larvae varies in both space and time (on a seasonal scale) and is consistent with the observed spatial and temporal recruitment patterns seen by sampling postlarval immigation into nursery areas. During the period of highest reproductive activity (March) in the southeastern corner of the Gulf, the area of the largest fishery, the advection of larvae is offshore and little recruitment of postlarvae to the nursery grounds is accomplished. Six months later, during the next period of reproductive activity (October), when the number of spawning female shrimp is much lower, the phase of the tidal currents, relative to the day-night cycle, has progressed 180° and the larvae are moved onshore allowing postlarvae access to their estuarine nursery grounds several months prior to the main fishing season (March)

Larval growth and survival optima for four species of penaeids from Australia, as indicated by their distribution and abundance in the field

Abstract only.Prawn catches from tropical northern Australia are dominated by four species of prawns: Penaeus merguiensis, P. semisulcatus, P. esculentus and P. latisulcatus. Three of the species (P. merguiensis, P. semisulcatus and P. latisulcatus) are widespread throughout the Indo-Pacific, while P. esculentus is endemic to northern and eastern Australia. The species appear, however, to have well defined and limited distribution on a smaller scale. Surveys of the larvae in the Gulf of Carpentaria, northern Australia, have shown both spatial and temporal heterogeneity in the abundance of all four of these species. Assessing the temperatures and salinities in which the larvae were caught may be a realistic indicator of conditions suitable for reproduction, as well as growth and survival of the larvae. Means of these distributions may be deemed optima and ranges indicate tolerances. Most of the larvae of all four species are found in water above 26°C and 31 ppt. However, the mean temperatures and salinities vary significantly between species. P. merguiensis has the lowest salinity optimum (31.8 ppt) and the highest temperature optimum (29.0°C). the other three species are similar for both temperature and salinity optima. P. latisulcatus has the lowest temperature optimum of 27.4°C compared with P. semisulcatus at 27.9°C and P. esculentus at 28.5°C. The salinity optima for these three species are almost indentical at approximately 33.2 ppt. While the ranges of temperatures of all four species are similar (21.5-30.6°C), the ranges of salinities in which the lar-vae are found coincide with the size of the biogeographic distribution of the species. The three widespread species have large salinity ranges: P. merguiensis, 26.2-34.9 ppt P. semisulcatus, 27.8-34.9 ppt: and P. latisulcatus, 28.6-34.9 ppt. The Australian endemic, P. esculentus, has the smallest and highest range, 30.1-34.6 ppt. This apparent inability of P. esculentus to tolerate low salinity water may restrict dispersal during the larval stages

SPECIFIC IDENTIFICATION AND ASSESSMENT OF DISTRIBUTION AND ABUNDANCE OF EARLY PENAEID SHRIMP LARVAE IN THE GULF OF CARPENTARIA, AUSTRALIA

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The influence of prostaglandin E2 and the steroid hormones, 17α-hydroxyprogesterone and 17β-estradiol on moulting and ovarian development in the tiger prawn, Penaeus esculentus Haswell, 1879 (Crustacea: Decapoda)

1. 1. During trials of 5 weeks duration, nine groups of adult female tiger prawns, Penaeus esculentus (carapace length >28 mm), were treated with prostaglandin E (PGE) (0.1 μg/g body weight), 17α-hydroxyprogesterone (0.01 μg/g body weight), 17β-estradiol (0.01 μg/g body weight), or a combination of these. Both ovarian development and moulting were individually monitored during this time, and upon completion, ovaries were weighed and histologically examined. 2. 2. Those groups treated with PGE, whether alone or in unison with a steroid hormone, displayed significantly shorter moult cycles than did either the control or steroid treated groups (P 0.05, two-way ANOVA; mean moult cycle duration of all non-PGE treated groups, 17.30 ± 0.39 days). 4. 4. Histological examination showed that no treatment significantly stimulated ovarian development. There was also no significant increase in mean ovary weight relative to body weight. This result questions a body of opinion which suggests that both 17α-hydroxyprogesterone and 17β-estradiol are vitellogenin stimulating hormones

Appendix A. Qualitative analysis of model stability and predictions of press perturbation response.

Qualitative analysis of model stability and predictions of press perturbation response

Migratory shorebirds of Moreton Bay

Tens of thousands of migratory shorebirds return to Moreton Bay each year from their breeding grounds in the Arctic. The Bay’s extensive tidal flats provide a rich feeding resource for the birds while they recuperate from their long migration flight and prepare for their next one. The abundance of many migratory shorebird species has declined dramatically in Moreton Bay, and while some of the causes are located elsewhere along the birds’ migration routes, there are significant threats to the birds and their habitats within the Bay, ranging from habitat loss to disturbance. New partnerships between conservation management agencies and NGOs have led to exciting examples of conservation action to reduce some of these threats, including collecting high quality monitoring data, careful zoning of recreational and commercial uses to avoid important areas for shorebirds, and extensive awareness-raising activities. Migratory shorebird conservation will become more and more critical as the human population using the Bay continues to increase over the coming decades

Quantitative Foresighting as a Means of Improving Anticipatory Scientific Capacity and Strategic Planning

In a rapidly changing world, scientists and research institutions need to plan for the infrastructure, skills, and policy engagement that will help society navigate social-ecological challenges. Foresighting draws on approaches used in strategic and long-range (>10 years) planning and participatory futures studies. Here, we describe a new quantitative approach to develop and rank 14 foresight scenarios across a range of general and marine-relevant science domains. Indicators for each foresight were used to assess the time-specific probability of each scenario being realized. Assessments by scientists in 2 consecutive years showed foresight scoring consistency and revealed surprises. Despite high variation among scientists in scoring the year that each indicator would occur, there was overall consistency across the foresights between years. We show that foresighting can be quantitative and that individual performance and changes in likelihood can be evaluated. This approach can motivate and guide strategic planning and investment decisions by scientific institutions in response to different anticipated futures and build skills in futures thinking

A database of chlorophyll a in Australian waters

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ The Creative Commons Public Domain Dedication waiver http://creativecommons.org/publicdomain/zero/1.0/ applies to the metadata files made available in this article.Chlorophyll a is the most commonly used indicator of phytoplankton biomass in the marine environment. It is relatively simple and cost effective to measure when compared to phytoplankton abundance and is thus routinely included in many surveys. Here we collate 173, 333 records of chlorophyll a collected since 1965 from Australian waters gathered from researchers on regular coastal monitoring surveys and ocean voyages into a single repository. This dataset includes the chlorophyll a values as measured from samples analysed using spectrophotometry, fluorometry and high performance liquid chromatography (HPLC). The Australian Chlorophyll a database is freely available through the Australian Ocean Data Network portal (https://portal.aodn.org.au/). These data can be used in isolation as an index of phytoplankton biomass or in combination with other data to provide insight into water quality, ecosystem state, and relationships with other trophic levels such as zooplankton or fish