Prawn Research Articles

Pertumbuhan Udang Galah (Macrobrachium Rosenbergii) yang Diberi Perlakuan Vegetable Floating Raft (VFR)

Galah shrimp is one type of freshwater shrimp that has great potential for cultivation. One of the obstacles to the growth of king prawns is water quality. This study was conducted to determine the effect of the installation of Vegetable Floating Raft (VFR) on the growth of king prawns (Macrobrachium rosenbergii). This study was conducted using the t-test method, with control and Vegetable Floating Raft treatments. The results showed that the growth pattern of weight and length of king prawns in each treatment was relatively the same. However, the daily weight growth rate of king prawns in the control treatment was greater at 3.36%, compared to the treatment of Vegetable floating raft at 1.26%, while the daily length growth rate of king prawns in the control treatment was 0.86%. The daily length growth rate in the Vegetable floating raft treatment was smaller at 0.61%. During the study the value of the degree of survival of the control treatment was 95%, while in the treatment of Vegetable floating raft the percentage of the degree of survival of king prawns was 62%. Based on the results of visual observations seen the rest of the feed and the rest of the skin during molting. It is suspected that shrimp are stressed due to changes in water quality characterized by increased ammonia levels in the last maintenance week caused by the death of kale plants in the maintenance medium.

Polychlorinated dibenzodioxins/furans and dioxin-like polychlorinated biphenyls in fish and crustaceans of a recreationally fished estuary, following targeted remediation

Polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) are a suite of harmful chemicals (hereafter collectively referred to as ‘dioxins’), and their emission into aquatic habitats leads to persistent contamination of sediments, aquatic food-webs, and seafoods. Quantifying contaminant levels in seafood species is important for the ongoing management of exposure risk by fishers, particularly after any remediation actions. We present dioxin concentrations in four seafood species (Yellowfin Bream Acanthopagrus australis, Sea Mullet Mugil cephalus, Eastern School Prawn Metapenaeus macleayi, and Eastern King Prawn Penaeus plebejus) in a recreationally fished estuary, in relation to a contaminated site that has undergone a remediation process, partially removing contaminated sediments (Homebush Bay, Port Jackson, New South Wales, Australia). Dioxin concentrations in these species were measured before (2005/6) and after (2015/16) remediation at a range of locations in and around the remediated site. Dioxin concentrations and congener profiles differed substantially among taxa, and concentrations were frequently higher than Australian screening criteria. The two prawn species showed evidence of a decline in dioxin concentrations after remediation, but the fish species only showed a declining dioxin concentration with distance from the contaminated site (not between periods). There were some minor changes in the congener profile for some species following remediation. While there was evidence for greatly reduced dioxin concentrations in prawn species following remediation, the complex patterns for fish were likely affected by environmental changes, species-specific and temporal changes in lipid content, and animal movement patterns. Future monitoring may aid interpretation of the patterns and modelling of exposure risk associated with seafood consumption into the future.

Eastern king prawn Penaeus plebejus stock enhancement-Genetic evidence that hatchery bred prawns have survived in the wild after release.

Eastern king prawn (Penaeus plebejus) is endemic to eastern Australia and is of high commercial and recreational value. As part of a recreational fisheries enhancement initiative, hatchery reared juveniles from Queensland were released into two, more Southern New South Wales (NSW) estuaries between 2014 and 2015. Responsible stock enhancement programs rely on knowledge of the population structure of the released species. Previously, in consideration of fisheries data, it was assumed the king prawn populations in Australia are one single breeding stock. In the present study, our first aim was to test this posit of no genetic differentiation using mtDNA control region (mtCR) sequences from the wild samples collected from four estuaries ranging from Queensland/NSW border (source of the stocked animals) to Southern NSW. The second objective was to test for signals of hatchery-released animals in the two stocked estuaries. All four surveyed populations had an extremely high level of haplotype diversity (average h = 99.8%) and low level of haplotype sharing between populations. Estimates of PhiPT values were <0.01 or close to zero and AMOVA test did not indicate any significant differences among populations. Further, phylogenetic analysis and principal coordinate analysis did not support division of samples by population. Collectively these results suggest that eastern king prawn populations along the NSW coast can be considered as a single stock and stocking from the Queensland samples will not necessarily impact the genetic composition of the overall stock. After stocking of two estuaries, sharing of haplotypes was moderate to very high in the stocked sites (>80% in some collections) but negligible in the two unstocked estuaries (≤2%, which is assumed to be background coancestry unrelated to the hatchery). Moreover, some haplotypes present in the hatchery broodstock were detected in stocked sites, but not in unstocked sites. The highest stocking signal was detected in the estuary which becomes isolated from the sea by sand barrier suggesting such "lakes" maybe more favourable for stocking than estuaries directly open to the sea. Findings in the current study should assist in designing and implementation of future prawn stocking programs.

Growth and population characteristics of the Western King Prawn Penaeus latisulcatus (Kishinouye, 1896) from the southeastern Mediterranean off the Egyptian coast

Penaeus latisulcatus (Kishinouye, 1896) is considered one of the most economically important penaeid shrimp species in the Egyptian Red Sea. Recently, it appeared in the Egyptian Mediterranean catches. The present study is concerned with the estimation of growth, age and population characteristics of the non-indigenous P. latisulcatus collected between the months of July 2020 to June 2021 from the landing fishing center of Boughaz El-Maadiyah (Egyptian Mediterranean coast). A total of 2214 individuals were collected monthly. The results showed that the females to males ratio was 1:0.98. According to the Chi-square test, there was no statistically significant difference between the sexes (X2 = 0.181, df = 1, P > 0.05). The distribution of the length frequency showed that the females varied from 5.0 cm to 19.2 cm (TL) with a mean length of 11.73 ± 2.78 cm, while the males ranged from 5.3 cm to 17.1 cm (TL) with a mean length of 10.97 ± 2.06 cm. Positive allometry was detected for the total length-total weight relationship. The parameters of von Bertalanffy were L∞ = 20.56 cm, K = 0.99 yr−1 and to = −0.178 yr−1 for females, L∞ = 18.68 cm, K = 1.05 yr−1 and to = −0.172 yr−1 for males, and L∞ = 20.74 cm, K = 0.90 yr−1 and to = −0.196 yr−1 for the combined sexes. The expected age of females and males were 2.6 and 2.2 years, respectively. According to the parameters obtained, the current exploitation rate of the population of P. latisulcatus was estimated at Ecur. = 0.59. The results indicated that the population of P. latisulcatus is being highly exploited in Boughaz El-Maadiyah landing center (Egyptian Mediterranean coast). Hence, it is important to manage the P. latisulcatus shrimp resources in the studied area. Furthermore, similar studies are recommended for P. latisulcatus along the Egyptian Mediterranean coast to evaluate variations between populations in different fishing areas. Moreover, further studies are needed about the new aspects of the reproductive activity of this species as well as its aquaculture to estimate its growth rate experimentally.

Plastics for dinner: Store-bought seafood, but not wild-caught from the Great Barrier Reef, as a source of microplastics to human consumers

• The presence of MP was examined in edible and discarded Australian seafood. • Store purchased fresh muscle tissue was heavily contaminated with MP. • Wild-caught seafood was completely free of MP within the edible muscle. • Most organisms examined were also free of MP within the GIT. • Contamination of edible seafood likely occurs after it has entered the human environment. Seafood accounts for more than 17% of the global consumption of animal protein, with an excess of 335000 t consumed in Australia throughout 2019-2020. Recently, the presence of microplastics (MPs) within commercial seafood and the potential vectorisation of MPs to human consumers has become a significant concern for the public and the scientific community. Here, four commonly harvested wild-caught marine organisms were assessed for MP presence. These species comprise a significant proportion of the Queensland seafood industry, as well as being highly desirable to Australian consumers. The edible muscle tissue and discarded digestive tissue (GIT) of barramundi ( Lates calcifer ), coral trout ( Plectropomus leopardus ), blue leg king prawns ( Melicertus latisulcatus ), and Ballot's saucer scallops ( Ylistrum balloti ), were analysed discretely to determine the extent to which these species may be contaminated in the wild (GIT tissue), and the extent to which they themselves may act as a vector for human exposure (edible muscle tissue). Wild-caught seafood was predominantly free of MPs, with digestive tissues from two of ten coral trout containing only two fibres each. All wild-caught muscle tissue samples were free of MPs, as was the GIT of scallops, prawns, and barramundi. On the other hand, fresh, skinless barramundi muscle tissues, purchased from various commercial suppliers, were examined and found to be significantly contaminated with MPs (0.02 - 0.19 MP g -1 ). Overall, these results highlight the growing consensus that food can become contaminated simply by being prepared in the human environment, and the focus must shift to determining the extent of MP proliferation within the processing and point-of-sale environment. Graphical abstract

Effects of spatial management of a penaeid fishery on other target fish species in eastern Australia

AbstractTemporal and spatial closures are often used to manage harvest by trawl fisheries. Trawl closures implemented to benefit a particular species may also benefit other species, but these indirect effects are rarely quantified. Using the New South Wales (Australia) Ocean Trawl Fishery as a case study, the potential unintended effects of trawl closures designed to protect juvenile eastern king prawn were explored for other quota managed Sillaginidae within the fishery (stout whiting Sillago robusta and eastern school whiting Sillago flindersii). Both species of whiting were more abundant within closed areas than adjacent areas, and spawning‐sized stout whiting were proportionally more abundant within closed areas. Thus, closures implemented to protect prawns also provided protection for exploited whiting species, including spawning‐sized individuals, enhancing their overall impact on the fishery. Spatial management of trawl fisheries elsewhere in the world may also similarly benefit other exploited species.

Adaptive Spatial Management to Deal with Postflood Inshore Bycatch in a Penaeid Trawl Fishery

AbstractAdaptive spatial management provides a way to balance the conservation of bycatch species and the potential economic effects of bycatch‐induced closures on a fishery, but implementation can be both data and resource intensive. We present a survey exploring a novel approach to adaptively manage an intermittent bycatch issue in an inshore trawl fishery where Sciaenidae bycatch species (including juvenile Mulloway Argyrosomus japonicus, a species of conservation concern) co‐occur with large aggregations of a valuable target species (eastern school prawn Metapenaeus macleayi), following flood‐induced egression from estuarine habitats. Diurnal sampling surveys followed three flood events and targeted permanent inshore closure zones (designed to protect the normally nocturnally harvested eastern king prawn Melicertus plebejus) and adjacent inshore nonclosure areas. Sciaenidae abundance was mostly &lt;10 fish/ha trawled, but larger catches generally corresponded with larger catches of eastern school prawn, and these relationships appeared to be steeper within nonclosure zones. There were only minor differences in the size structure of eastern school prawn between zones, and patterns were event and location specific. Negligible eastern king prawn were encountered. The results show that temporarily allowing fishers access to permanent trawl closures following floods may support the exploitation of aggregated target species with reduced interaction with bycatch species of concern. The approach presented here is relevant to the consideration of adaptive spatial management in other trawl fisheries.

Modelling the potential consequences of adaptive closure management in a penaeid trawl fishery

Spatial management of fishing effort can be used to avoid catching undesirable size classes for target species, and improve yield-per-recruit for the exploited stock. Adaptive closure management has been proposed as a means to more effectively utilise spatial management, however these management provisions often lack quantitative evaluation which constrains the information available to inform decisions. We demonstrate the use of a spatially and size structured population dynamics model to evaluate the potential impact of spatial management on a multijurisdictional fishery for a highly migratory species (eastern king prawn, Penaeus [Melicertus] plebejus). Under current conditions in the fishery, the overall effect of closures on harvest was estimated to be comparatively minor, regardless of assumptions about how effort or fisher behavior are affected by spatial management. Alternative assumptions about the movement patterns of eastern king prawn had little influence on the impact of closures on overall harvest. However, when effort was increased to historic levels similar to those observed when the closures were implemented, a much greater impact on overall harvest was observed. The approach taken and simulation outcomes are discussed in the context of spatial management for both eastern king prawn, and penaeid fisheries more broadly.

Biological evaluation of an existing spatial management network for an exploited penaeid species

Spatial management may be employed to achieve objectives aimed at maintaining or enhancing productivity and sustainability of exploited populations. Spatial management is used in penaeid fisheries to alter the spatiotemporal distribution of fishing effort to achieve outcomes such as avoidance of undesirable size-classes. Eastern King Prawn (Penaeus [melicertus] plebejus; EKP) is a valuable penaeid species for which harvest is supported by an extensive spatial management network, however these closures have never been evaluated. We examine temporal variation in biomass and size structures within three trawl closure areas spanning four degrees of latitude. There was substantial spatial variation in EKP biomass among locations, fished and non-fished zones and sampling periods, which appeared to be influenced by depth, temperature and distance to the adjacent estuarine nursery. Size structure varied among locations and sampling periods, and differed inside and outside of closure areas, however in many cases the majority of prawns that were protected within closure areas were consistently smaller than the estimated size at first capture for optimal yield per recruit. The data suggest that the closures are likely to be effective at achieving their objective, but there may be some scope for adaptive management.

Connectivity between a spatial management network and a multi-jurisdictional ocean trawl fishery

Spatial management is often applied in penaeid trawl fisheries to avoid non-optimal size classes of target species, by providing areas of refuge from trawl fishing effort. Efficient application of spatial management relies on having a detailed knowledge of animal movements, particularly for species with complex life histories. Using Eastern King Prawn (Penaeus (Melicertus) plebejus; EKP) as a case study, we examine how spatial and temporal factors can influence connectivity between a spatial management network designed to protect small prawns from capture by trawlers, and a multi-jurisdictional (Queensland [Qld] and New South Wales [NSW]) fishery. Over 7500 prawns were tagged across multiple years in three northern NSW spatial management areas, and 786 tagged prawns were recaptured across both jurisdictions. The majority of prawns tended to be recaptured from deeper waters adjacent to, or directly north of, the spatial management areas, but tagging location and release timing influenced recapture patterns. Cohorts tagged early in the growth season showed lower recapture rates, but were larger on average at recapture, and had migrated further. Prawns reached the fishery in the adjacent jurisdiction (Qld) within 54 days-post tagging, but for most cohorts the majority of recaptures were in NSW zones. Overall, there was good connectivity between all spatial management areas and the NSW fishery, and tagged prawns also reached the Qld spawning areas. This represents an optimal scenario for NSW fishers (who forgo capture of prawns within these spatial management areas): the prawns protected in the closure areas primarily contribute to harvest of larger sized prawns within NSW waters; and a portion of the protected prawns survive to reach the southern Queensland spawning grounds, which is the primary source of recruits for northern NSW nurseries. These findings are broadly relevant to defining the role and impact of established and proposed spatial management networks within penaeid fisheries.

Survival and Growth Promoting Effects of Bacillus subtilis on Macrobrachium rosenbergii, and Validation of Gut Microflora

This work emphasized the survival and growth of the commercially important freshwater prawn, Macrobrachium rosenbergii post-larvae on formulated diets supplemented with a probiotic bacterium, Bacillus subtilis at five different serially diluted concentrations (10-1, 10-3, 10-5, 10-7 and 10-9). After 90 days of feeding, 10-7 (CFU, 2.76×10-7) concentration has produced the best results in increased survival rate, weight gain, basic biochemical constituents (total protein, amino acid, carbohydrate and lipid) and activities of digestive enzymes (protease, amylase and lipase) when compared with control diet prepared without B. subtilis. This was due to maintenance of good intestinal health, because of B. subtilis supplementation. The presence of B. subtilis, Bacillus cereus, Lactobacillus delbrueckii (subsp. bulgaricus), Lactobacillus casei, Lactobacillus rhamnosus and Streptococcus pyogenes have been identified in the gut of M. rosenbergii fed with B. subtilis supplemented diet, through 16S r-RNA gene sequencing and authenticated with NCBI GenBank. The pathogenic bacteria such as Escherichia coli, Klebsiella spp., and Staphylococcus spp., present in the control prawns as per our previous study (Manjula et al., 2018) have competitively been excluded by the experimental prawns fed with B. subtilis supplemented diet in the present study. Therefore, B. subtilis is recommended for sustainable production of M. rosenbergii seed.

Reproductive traits of the freshwater prawn Macrobrachium amazonicum (Decapoda: Palaemonidae) in an isolated water reservoir

The aim of this study was to analyze the reproductive period, fecundity, egg size and reproductive output (RO) of a hololimnetic population of Macrobrachium amazonicum. The prawns were collected monthly, from May 2017 to April 2018, in a water reservoir isolated from river connections, in Severinia (20o49’31.92” S, 48o49’39.55” W), Sao Paulo, Brazil. Ovigerous females were preserved individually in 70% ethanol. The reproductive period was calculated based on the monthly percentage of ovigerous females. The egg mass was weighed and partially measured. The eggs were counted and classified according to the embryonic developmental stage. The reproductive output was calculated individually by dividing the dry weight of females without eggs by the mass of eggs. The reproductive period was continuous, with peaks in the dry season. Egg volume differed among stages and seasons (ANCOVA, p < 0.05), being larger in the rainy season. The reproductive output differed between seasons (rainy: 12.5 ± 4.8%; dry: 13.9 ± 5.4%, p < 0.05), as well as fecundity (rainy: 585 ± 304 eggs; dry: 613 ± 306 eggs, p < 0.05). We concluded that the reproductive traits of this population differ from those of other populations of M. amazonicum previously studied, and that these differences may be consequences of the isolation of this population.

Enhancement of antimicrobial properties of shoe lining leather using chitosan in leather finishing

In this study, a chitosan based coating method was developed and applied on the shoe lining leather surface for evaluating its inhibition to bacterial and fungal attacks. At first, chitosan was prepared from raw prawn shells and then the prepared chitosan solution was applied onto the leather surface. Secondly, the characterization of the prepared chitosan and chitosan treated leather was performed by solubility test, ATR-FTIR, XRD pattern, SEM and TGA. Evaluation of antimicrobial efficacy of chitosan was assessed against two gram positive, two gram negative bacteria and a reputed fungi by agar diffusion test. The results of this study demonstrated that chitosan took place in both the surface of collagen fibres and inside the collagen matrix of crust leather. The chitosan showed strong antimicrobial activities against all the tested microorganisms and the inhibition increased with increasing percentage of chitosan. Therefore, the prepared chitosan in this study can be an environment friendly biocide, which functions simultaneously against different spoilage bacteria and fungi on the finished leather surface. Thus by using the prepared chitosan in shoe lining leather, the possibility of microbial attack during shoe wearing can be minimized which is one of the important hygienic requirements of footwear.

Improving penaeid-trawl efficiencies via ground gear with tickler chains

Penaeid trawls often have poor ecological efficiencies measured as unwanted bycatches (with high discard mortality) and <100% effectiveness for all penaeids interacting with the ground gear (with some escape mortality). This study investigated the utility of varying ground-chain size (8- vs 10-mm diameter (Ø) stainless-steel chain) and the present or absence of a tickler chain (4-mm Ø) for improving efficiencies an Australian fishery diurnally targeting school, Metapenaeus macleayi and eastern king prawns, Penaeus plebejus. There were no treatment effects on wing-end spread and therefore areas trawled. Irrespective of the tickler chain, increasing the ground-chain Ø reduced catches of total penaeids (by 14%) and jellyfish, Catostylus mosaicus (by 39%)—results speculatively attributed to variation in ground contact and/or a slightly higher footrope in trawls with the 10-mm Ø chain. By comparison, installing the tickler chain had no effect on eastern king prawns, but increased catches of school prawns (by 1.13×) and bycatches of blue swimmer crabs, Portunus armatus (1.52×; a species with a low discard mortality) and jellyfish (1.23×), while reducing bycatches of two species with high discard mortalities: southern herring, Herklotsichthys castelnaui (by 38%) and squid, Uroteuthis sp. (37%). The results were attributed to the tickler chain producing (1) mechanical stimuli that augmented the capture of benthic-orientated school prawns (but not eastern king prawns owing to diel variations in emergence from the substrata), blue swimmer crabs and jellyfish; and (2) visual stimuli that possibly enabled some southern herring and squid to detect the trawl and escape. The data show tickler chains can improve trawl efficiency for penaeids with at least some positive effects on bycatch that should be rationalised in terms of species-specific vulnerabilities to unaccounted fishing mortality.

Evaluation of adaptive spatial management in a multi-jurisdictional trawl fishery

Management of exploited resources that span multiple jurisdictions can be complex, with activities in one area potentially affecting productivity in another. Consequently, management decisions need to consider implications across the entire area in which the resource occurs. The study presents a unique study design that examines the impact of spatial management across two jurisdictions in an Australian penaeid multi-jurisdictional trawl fishery. Specifically, two areas relevant to Eastern King Prawn (Penaeus [Melicertus] plebejus; EKP, an important penaeid species harvested across eastern Australia) that are closed to trawling (on a permanent, and temporary basis) were evaluated using a combination of trawl and tag-recapture surveys. Over 1,250 EKP were tagged and released across the permanent and temporary trawl closure, and ∼15.4% of all tagged prawns were recaptured and reported by fishers in both New South Wales (33% of recaptures) and the adjacent jurisdiction of Queensland (67% of recaptures, up to 730 km from the point of tagging) during 7 months post-tagging. There were significant differences in prawn size and abundance across the permanent and temporary trawl closure areas with both depth and distance to the adjacent estuarine nursery explaining these patterns, but prawns generally exceeded the minimum size-at-first-capture estimated by relevant yield per recruit models before they left areas closed to trawling. While more prawns were captured in Queensland, recapture rates were far greater in New South Wales when standardised by relative effort. Patterns in these data highlight the broader considerations of spatial management in multi-jurisdictional fisheries.

Evidence for inter- and intraspecific trophic niche separation among deepwater elasmobranchs on the southern Great Barrier Reef, Australia

Quantifying the trophic structure and interactions of deepwater (&gt;200 m depth) elasmobranch assemblages is required to improve our understanding of deepwater ecosystems and the impacts of increased deepwater exploitation. To this end, we investigated the trophic ecology of deepwater elasmobranchs on the Great Barrier Reef (GBR) using a stable isotope (δ13C and δ15N) approach. Our study included 4 species captured in the southern GBR deepwater eastern king prawn trawl fishery: the eastern spotted gummy shark Mustelus walkeri, the piked spurdog Squalus megalops, the pale spotted catshark Asymbolus pallidus, and the Argus skate Dentiraja polyommata. The δ13C and δ15N values of all 4 species ranged from -18.6 to -16.2‰ and 8.3 to 13.8‰, respectively. The small δ13C range was likely due to the limited number of unique carbon baseline sources typically found in deepwater environments. Despite this, 3 of the 4 species exhibited relatively low core (40% SEAb) isotopic niche overlap (&lt;1 to 44%). Isotopic niche separation may be driven by multiple interacting factors including morphology, feeding strategies, or resource partitioning to reduce competition. Isotope analysis also provided evidence for intraspecific variation; S. megalops, D. polyommata and M. walkeri exhibited significant increases in δ15N (~3‰) and δ13C (~2‰) with size. Latitude, longitude, and depth had statistically significant but comparatively minor effects on isotope values (≤1‰) of the 4 species. Cumulatively, our results indicate that isotopic variation among deepwater elasmobranchs on the GBR is principally driven by size and species-level differences in resource use.

Therapeutic effects of HESA-A (a herbal-marine compound) in acute organophosphorus pesticide poisoning.

Organophosphorus compounds (OPs) are common causes of poisonings. Atropine and oximes are pharmacological antidotes of OPs. However, because of their adverse effects and insufficient performance, several other compounds have been evaluated as adjuvant therapy. HESA-A is a herbal-marine drug that contains material from Carum carvi(Persian cumin),Penaeus latisculatus(king prawn),andApium graveolens (celery) with anti-inflammatory and antioxidants properties, which has shown useful effects as adjuvant therapy on some diseases. We have evaluated the effect of HESA-A on 69 moderate to severe acute OPs poisoned patients (44 HESA-A treated and 25 controls) as an adjuvant drug. Two randomized age and sex matched groups of OPs poisoned patients were treated in Medical Toxicology Center of Imam Reza hospital, Mashhad, by conventional therapy with or without HESA-A (50 mg/kg/day orally). The evaluation criteria were total administrated doses of atropine and pralidoxime, intensive care unit (ICU) admission rate, mechanical respiration need, number of hospitalization days and mortality. There were no significant differences between the morbidity and mortality rate criteria of the two groups; moreover, we did not observe significant adverse effects for HESA-A. HESA-A did not reduce morbidity and mortality of OPs poisoning and did not induce any major side effect in the patients.

Stable isotopes reveal the importance of saltmarsh-derived nutrition for two exploited penaeid prawn species in a seagrass dominated system

Estuaries represent highly important nursery habitats for a range of species, with refuge and nutrition being two key benefits derived from estuaries. Quantifying these benefits provides us with a means for enhancing fisheries productivity. Metapenaeus macleayi (School Prawn) and Penaeus plebejus (Eastern King Prawn) are two commercially and recreationally important species in New South Wales that utilise estuarine nurseries throughout their life history. In this study, stable isotopes of carbon, nitrogen and sulfur were used to determine the proportional contribution of primary producers to prawn nutrition in Brisbane Water (NSW). Both the saltmarsh grass Sporobolus virginicus and seagrass Zostera muelleri were found to support a high trophic contribution to prawns (up to 53% and 40%, respectively). The contributions of other primary producers such as mangroves, fine benthic organic matter (FBOM) and C3 saltmarsh plants were generally found to be much lower (0.7–15%). Such findings are generally consistent with patterns observed in other south-east Australian estuaries, however such a dominant role of saltmarsh in the presence of seagrass is a novel finding. These results highlight linkages between habitats of conservation concern and highly valuable fisheries species, and the benefit of using sulfur as an additional marker in Bayesian mixing models examining estuarine food webs.

Scales of spatial and temporal variation of small bodied nekton within intermittently closed/open lakes and lagoons (ICOLLs) in south-eastern Australia

Intermittently open/closed lakes and lagoons (ICOLLs) are common in temperate regions of the southern hemisphere and are also found in parts Europe and North America. They are important nursery grounds for a variety of fish and crustacean species, and while they are regularly studied for a variety of purposes, dedicated analysis aimed at identifying levels of spatial and temporal variance, particularly for abundant smaller nekton are lacking. A hierarchical study was undertaken using cast nets, spanning four estuaries at multiple nested spatial and temporal scales to determine at which levels greater variation occurs. The four most common species including Glassfish (Ambassis jacksoniensis), Small-mouth Hardyhead (Atherinosoma microstoma), Eastern King Prawn (Penaeus plebejus) and Glass Shrimp (Macrobrachium intermedium) were considered separately. A consistent pattern emerged where high levels of spatial variance occurred among individual samples, while the least was generally observed among sites nested within estuaries. A similar pattern occurred when the nekton community was considered as a whole. However levels of residual variation were reduced by pooling individual casts into fewer replicates from each site, resulting most notably in an increase in the variation attributed to the Estuary scale. This produced a good balance in capturing both the small scale variation and broader patterns among estuaries. Temporal levels of variation were lower than the spatial observations for all four common species, as well as the community as a whole. However, greater variation was observed among seasons compared to months nested within seasons. These findings should provide guidance for future studies in ICOLLs where an efficient sampling program would focus on increased replicate samples within a site rather than sampling a large number of sites within a system and focus on seasonal variation.

Stable isotopes infer the value of Australia’s coastal vegetated ecosystems from fisheries

AbstractWild capture fisheries provide substantial input to the global economy through employment and revenue. The coastal zone is especially productive, accounting for just 7% of the total area of the ocean, but supporting an estimated 50% of the world's fisheries. Vegetated coastal ecosystems—seagrass meadows, tidal marshes and mangrove forests—are widely cited as providing nutritional input that underpin coastal fisheries production; however, quantitative evidence of this relationship is scarce. Using Australia as a case study, we synthesized fisheries stable isotope data to estimate nutritional input derived from coastal vegetated ecosystems and combined these “proportional contribution” estimates with total annual catch data from commercial fisheries to determine species‐specific dollar values for coastal vegetated ecosystems. Based on the data from 96 commercially important fish species across Australian states (total landings 14 × 106 tonnes pa), we provide a conservative estimate that Australia's coastal vegetated ecosystems contribute at least 78 million AUD per year to the fisheries economy. Two thirds of this contribution came from tidal marshes and seagrasses that were both equally valued at 31.5 million AUD per year (39.4%) followed by mangroves at 14.9 million AUD per year (18.6%). The highest dollar values of coastal ecosystems originated from eastern king prawn (Melicertus plebejus) and giant mud crab (Scylla serrata). This study demonstrates the substantial economic value supported by Australia's coastal vegetated ecosystems through commercial fisheries harvest. These estimates create further impetus to conserve and restore coastal wetlands and maintain their support of coastal fisheries into the future.