Extraordinarily high biomass benthic community on Southern Ocean seamounts

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

Synthesis: exotic and cryptogenic species in Port Phillip Bay

As the 20th century closes, the effects of human alterations on the marine environment are becoming increasingly apparent (Lubchenco et al. 1991; Vitousek et al. 1997)..

Age and growth of the cold-water scleractinian Solenosmilia variabilis and its reef on SW Pacific seamounts

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

The Introduced Species of Port Phillip Bay, Victoria

Port Phillip Bay is a large, temperate embayment in southeastern Australia that borders the major metropolitan areas of Melbourne and Geelong. The bay has been a focus for shipping activity since the mid-1800's and is currently a major destination for a wide range of coastal and international shipping. Port Phillip Bay has also been the focus of a number of historical biological surveys, which makes possible an evaluation of historical patterns of invasion by exotic marine species. A detailed analysis was undertaken of the introduced (known and cryptogenic) organisms in Port Phillip Bay. The analysis consisted of: • reviews of the historical information, published literature, and material in private and museum collections for all groups for which local taxonomic expertise was available; • detailed examinations, including new surveys undertaken as part of this study, of the biota in high risk areas; • documentation and re-analysis of the possible impacts of exotic species on the ecology of Port Phillip Bay; and • an evaluation of the broad patterns of invasion and an analysis of possible vectors for the introduction of the exotic species recorded from the bay. Although the scope of the analysis was restricted by the taxonomic expertise available, coverage included all major benthic phyla. However, for several major groups (annelids, crustaceans, molluscs and echinoderms) the narrow focus of earlier surveys limited the analysis to the soft bottom biota. The study identified 165 introduced and cryptogenic species (99 and 66, respectively), one species that was known to have been introduced but has subsequently become locally extinct, and another 13 species identified as 'potentially' introduced into Port Phillip Bay but whose status could not be confirmed due to the absence of voucher specimens or collections. Depending upon the criteria used, therefore, we identified between 99 ( confirmed introductions with voucher specimens) and 178 (all reports) introduced species in Port Phillip.Bay. For those groups for which a comparison was possible, exotic species constitute 10- 20% of the benthic biota of the bay. From a comparison of the total known biota of the bay and species numbers obtained from the more limited taxonomic and habitat coverage of this study, we estimate the actual number of exotic marine species in Port Phillip Bay at 300--400 species. We further estimate that 2-3 new exotic species are establishing in Port Phillip Bay each year. The major source region for these species is the North East Atlantic and the historically dominant transport vector is vessel hull fouling. However, there are exotic species in Port Phillip Bay from all of the world's major bioregions ( except the Antarctic) and evidence for the operation of a diverse range of introduction vectors. The rate of invasions appears to have increased over the last several decades; this increase coincides with an increasing prominence of the North West Pacific as a source region and ballast water as an introduction vector. Several of the most recent high profile introductions to the bay, however, are the result of domestic translocations of species introduced elsewhere in Australia and appear to be mediated by vessel fouling. The number of established exotic and cryptogenic species in Port Phillip Bay is higher than reported by similar studies anywhere else in the world. This reflects at least in part the depth of the analysis we undertook, but also the current and historical role of Port Phillip Bay as a major domestic and international port, and its apparent susceptibility to biotic invasion. Recent shifts in the dominant source regions and introduction vectors suggest a renewed potential for invasions and point to the need to develop and implement effective measures to minimise this threat and protect the bay's marine communities

Effects of chronic low carbonate saturation levels on the distribution, growth and skeletal chemistry of deep-sea corals and other seamount megabenthos

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 undersaturation 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

Life Cycles in Marine Ornamental Species : Fishes as a Case Study

27 pagesMarine ornamental fish show a great variety of sexual patterns that are the result of specific evolutionary selections and environmental adaptation. Most of the species can be divided into pelagic and demersal spawners. Pelagic spawners usually release gametes in the water column at dusk while demersal spawners have adhesive embryos and parental care. These two modes of reproduction show several differences and specificities, and are fully analyzed in the present chapter. This information is fundamental to the selection of the appropriate species to culturePeer Reviewe

Preservation effects on the isotopic and elemental composition of skeletal structures in the deep-sea bamboo coral Lepidisis spp. (Isididae)

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Colour pattern as a single trait driving speciation in Hypoplectrus coral reef fishes?

Theory shows that speciation in the presence of gene flow occurs only under narrow conditions. One of the most favourable scenarios for speciation with gene flow is established when a single trait is both under disruptive natural selection and used to cue assortative mating. Here, we demonstrate the potential for a single trait, colour pattern, to drive incipient speciation in the genus Hypoplectrus (Serranidae), coral reef fishes known for their striking colour polymorphism. We provide data demonstrating that sympatric Hypoplectrus colour morphs mate assortatively and are genetically distinct. Furthermore, we identify ecological conditions conducive to disruptive selection on colour pattern by presenting behavioural evidence of aggressive mimicry, whereby predatory Hypoplectrus colour morphs mimic the colour patterns of non-predatory reef fish species to increase their success approaching and attacking prey. We propose that colour-based assortative mating, combined with disruptive selection on colour pattern, is driving speciation in Hypoplectrus coral reef fishes