scholarly journals The Differential Importance of Deep and Shallow Seagrass to Nekton Assemblages of the Great Barrier Reef

Diversity ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 292
Author(s):  
Matthew A. Hayes ◽  
Eva C. McClure ◽  
Paul H. York ◽  
Kristin I. Jinks ◽  
Michael A. Rasheed ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Barrier Reef ◽  
Catch Per Unit Effort ◽  
Size Spectra ◽  
Spectra Analysis ◽  
Important Species ◽  
Seagrass Meadows ◽  
Unit Effort ◽  
Penaeus Semisulcatus ◽  
Different Depths

Seagrass meadows are an important habitat for a variety of animals, including ecologically and socioeconomically important species. Seagrass meadows are recognised as providing species with nursery grounds, and as a migratory pathway to adjacent habitats. Despite their recognised importance, little is known about the species assemblages that occupy seagrass meadows of different depths in the coastal zone. Understanding differences in the distribution of species in seagrass at different depths, and differences in species diversity, abundance, biomass, and size spectra, is important to fully appreciate both the ecological significance and economic importance of these seagrass meadows. Here, we assess differences in the assemblage characteristics of fish, crustacea, and cephalopods (collectively, nekton) between deep (>9 m; Halophila spinulosa dominant) and shallow water (<2 m; Halodule uninervis and/or Zostera muelleri dominant) seagrass meadows of the central Great Barrier Reef coast of Queensland, Australia. Nekton assemblage structure differed between deep and shallow seagrass. Deeper meadows were typified by juvenile emperors (e.g., Lethrinus genivittatus), hairfinned leatherjacket (Paramonacanthus japonicus) and rabbitfish (e.g., Siganus fuscescens) in both biomass per unit effort (BPUE) and catch per unit effort (CPUE), whereas shallow meadows were typified by the green tiger prawn (Penaeus semisulcatus) and pugnose ponyfish (Secutor insidiator) in both BPUE and CPUE. Both meadow depths were distinct in their nekton assemblage, particularly for socioeconomically important species, with 11 species unique to both shallow and deep meadows. However, both meadow depths also included juveniles of socioeconomically important species found in adjacent habitats as adults. The total nekton CPUE was not different between deep and shallow seagrass, but the BPUE and body mass of individual animals were greater in deep than shallow seagrass. Size spectra analysis indicated that in both deep and shallow meadows, smaller animals predominated, even more so than theoretically expected for size spectra. Our findings highlight the unique attributes of both shallow and deeper water seagrass meadows, and identify the distinct and critically important role of deep seagrass meadows within the Great Barrier Reef World Heritage Area (GBRWHA) as a habitat for small and juvenile species, including those of local fisheries value.

scholarly journals Comparative demography of commercially important species of coral grouper, Plectropomus leopardus and P. laevis , from Australia's great barrier reef and Coral Sea marine parks

2020 ◽  
Vol 97 (4) ◽  
pp. 1165-1176
Author(s):  
Samuel D. Payet ◽  
Jake R. Lowe ◽  
Bruce D. Mapstone ◽  
Morgan S. Pratchett ◽  
Tane H. Sinclair‐Taylor ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Barrier Reef ◽  
Important Species ◽  
Coral Sea ◽  
Comparative Demography ◽  
Commercially Important ◽  
Plectropomus Leopardus

scholarly journals Fishing Effort and Associated Catch per Unit Effort for Small-Scale Fisheries in the Mozambique Channel Region: 1950–2016

2021 ◽  
Vol 8 ◽  
Author(s):  
Dirk Zeller ◽  
Gabriel M. S. Vianna ◽  
Matthew Ansell ◽  
Angie Coulter ◽  
Brittany Derrick ◽  
...  
Keyword(s):  
Fishing Effort ◽  
Small Scale ◽  
Catch Per Unit Effort ◽  
Important Species ◽  
Small Scale Fisheries ◽  
Mozambique Channel ◽  
Fishing Vessels ◽  
Unit Effort ◽  
Fishing Capacity ◽  
Channel Region

The Mozambique Channel region in East Africa has diverse marine ecosystems and serves as a migratory corridor for economically important species. Local and foreign industrial fisheries operate in the Mozambique Channel, but regional small-scale fisheries are the crucially important fisheries that provide food security, livelihoods, and economic opportunities for rural coastal communities. This study reconstructed and investigated trends in the fishing effort and catch per unit effort (CPUE) of small-scale marine fisheries in four Exclusive Economic Zones (EEZ) that constitute the Mozambique Channel, i.e., Union of Comoros, Madagascar, Mayotte, and Mozambique, from 1950 to 2016. Effective fishing effort for small-scale fisheries in the form of fishing capacity in kWdays (i.e., kilowatt days) was derived using the number, length, motorization (engine power) by fishing vessels, as well as an approximate human-powered equivalent for shore-based fishers without vessels, as well as days of fishing per year. Effective small-scale fishing effort in the Mozambique Channel increased by nearly 60 times from just over 386,000 kWdays in 1950 to over 23 million kWdays in 2016. Correspondingly, the overall small-scale CPUE, based on previously and independently reconstructed catch data declined by 91% in the region as a whole, from just under 175 kg⋅kWday–1 in the early 1950s to just over 15 kg⋅kWday–1 in recent years. All four EEZs showed the strongest declines in the small-scale CPUE in the earlier decades, driven by motorization and growth in vessel numbers impacting effective fishing effort. Increased motorization combined with a substantial growth in overall vessel numbers were the drivers of the increasing fishing effort and decreasing CPUE, and clearly suggest that continuing to increase the fishing capacity of small-scale fisheries in the absence of effective and restrictive management actions may exacerbate overexploitation risk.

scholarly journals Spatial and Temporal Patterns in Macroherbivore Grazing in a Multi-Species Tropical Seagrass Meadow of the Great Barrier Reef

Diversity ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 12
Author(s):  
Abigail L. Scott ◽  
Paul H. York ◽  
Michael A. Rasheed
Keyword(s):  
Great Barrier Reef ◽  
Large Scale ◽  
Barrier Reef ◽  
Important Process ◽  
Spatial And Temporal Patterns ◽  
Video Cameras ◽  
Seagrass Meadows ◽  
One Year ◽  
The Impact ◽  
Green Island

Macroherbivory is an important process in seagrass meadows worldwide; however, the impact of macroherbivores on seagrasses in the Great Barrier Reef (GBR) has received little attention. We used exclusion cages and seagrass tethering assays to understand how the intensity of macroherbivory varies over space and time in the seagrass meadows around Green Island (Queensland), and what impact this has on overall meadow structure. Rates of macroherbivory were comparatively low, between 0.25–44% of daily seagrass productivity; however, rates were highly variable over a one-year period, and among sites. Loss of seagrass material to macroherbivory was predominantly due to fish; however, urchin herbivory was also taking place. Macroherbivory rates were of insufficient intensity to impact overall meadow structure. No macroherbivory events were identified on video cameras that filmed in the day, indicating that feeding may be occurring infrequently in large shoals, or at night. While relatively low compared to some meadows, seagrass macroherbivory was still an important process at this site. We suggest that in this highly protected area of the GBR, where the ecosystem and food webs remain largely intact, macroherbivory was maintained at a low level and was unlikely to cause the large-scale meadow structuring influence that can be seen in more modified seagrass systems.

scholarly journals Habitat complexity influences the structure of food webs in Great Barrier Reef seagrass meadows

Ecosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
Author(s):  
Kristin I. Jinks ◽  
Christopher J. Brown ◽  
Michael A. Rasheed ◽  
Abigail L. Scott ◽  
Marcus Sheaves ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Food Webs ◽  
Habitat Complexity ◽  
Barrier Reef ◽  
Seagrass Meadows

Microsporidiosis in prawns from Northern Australia

1988 ◽  
Vol 39 (3) ◽  
pp. 301 ◽  
Author(s):  
L Owens ◽  
JS Glazebrook
Keyword(s):  
Connective Tissue ◽  
Great Barrier Reef ◽  
Striated Muscle ◽  
The Body ◽  
Barrier Reef ◽  
Northern Australia ◽  
Brood Stock ◽  
Peripheral Muscle ◽  
Penaeus Semisulcatus ◽  
Low Prevalence

Two hundred thousand prawns from northern Australia were examined grossly for microsporidiosis. Ameson sp. was found infecting Penaeus semisulcatus, P. merguiensis and P. esculentus at low prevalence levels (<0.1%) across northern Australia. Thelohania sp, infected P. latisulcatus, P. longistylus and P. semisulcatus on the Great Barrier Reef, again at low prevalence levels (<0.1%). Histological attempts to find subclinical infections were unsuccessful. Ameson sp. infected the striated muscle bundles throughout the body, whereas Thelohania sp. infected mainly connective tissue, most organs and peripheral muscle bundles. Microsporidiosis is of concern, because it has been diagnosed from all areas where brood-stock females are collected for use in mariculture.

scholarly journals Quantifying the environmental impact of a major coal mine project on the adjacent Great Barrier Reef ecosystems

2021 ◽  
Author(s):  
Antoine Saint-Amand ◽  
Alana Grech ◽  
Severine Choukroun ◽  
Emmanuel Hanert
Keyword(s):  
Great Barrier Reef ◽  
Coal Mine ◽  
Marine Species ◽  
Ocean Model ◽  
Barrier Reef ◽  
Dispersal Patterns ◽  
Long Distance ◽  
Sediment Dispersal ◽  
Seagrass Meadows ◽  
Sediment Types

A major coal mine project in Queensland, Australia, is currently under review. It is planned to be located about 10 km away from the Great Barrier Reef World Heritage Area (GBRWHA). Sediment dispersal patterns and their impact on marine ecosystems have not been properly assessed yet. Here, we simulate the dispersal of different sediment types with a high-resolution ocean model, and derive their environmental footprint. We show that sediments finer than 32 µm could reach dense seagrass meadows and a dugong sanctuary within a few weeks. The intense tidal circulation leads to non-isotropic and long-distance sediment dispersal patterns along the coast. Our results suggest that the sediments released by this project will not be quickly mixed but rather be concentrated where the most valuable ecosystems are located. If accepted, this coal mine could therefore have a far-reaching impact on the GBRWHA and its iconic marine species.

scholarly journals Assessment of water quality from the Normanby River catchment to coastal flood plumes on the northern Great Barrier Reef, Australia

2018 ◽  
Vol 69 (6) ◽  
pp. 859 ◽  
Author(s):  
C. Howley ◽  
M. Devlin ◽  
M. Burford
Keyword(s):  
Great Barrier Reef ◽  
Inorganic Nitrogen ◽  
Suspended Sediments ◽  
River System ◽  
Marine Ecosystems ◽  
Coastal Ecosystems ◽  
Barrier Reef ◽  
Tropical River ◽  
Seagrass Meadows ◽  
Suspended Sediment Concentrations

Understanding the flux and fate of nutrients and sediments from rivers is of global importance because of the effects of these materials on coastal ecosystems. The present study followed three flood events from upper tributaries of the Normanby River to Princess Charlotte Bay in the northern Great Barrier Reef (GBR) lagoon, Australia. During each event, nutrients and suspended sediment concentrations were measured along a freshwater to marine transect. The upper catchment provided the majority of suspended sediments and nutrients supplied to the river system, although concentrations of most materials decreased by 52–85% between the upper catchment and estuary. As an exception, ammonium concentrations doubled within the estuary, indicating that undisturbed coastal ecosystems can provide a significant source of dissolved inorganic nitrogen to tropical river flood plumes. The dissolved nutrients in floodwaters stimulated phytoplankton blooms that inundated seagrass meadows and coral reefs. Northern GBR marine ecosystems are increasingly threatened by climate change and catchment development. The results of this study show that increased anthropogenic loads of nutrients and sediments from the upper Normanby catchment have the potential to affect the condition of marine ecosystems at Princess Charlotte Bay.

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