A hierarchical approach to defining marine heatwaves

Marine heatwaves (MHWs) have been observed around the world and are expected to increase in intensity and frequency under anthropogenic climate change. A variety of impacts have been associated with these anomalous events, including shifts in species ranges, local extinctions and economic impacts on seafood industries through declines in important fishery species and impacts on aquaculture. Extreme temperatures are increasingly seen as important influences on biological systems, yet a consistent definition of MHWs does not exist. A clear definition will facilitate retrospective comparisons between MHWs, enabling the synthesis and a mechanistic understanding of the role of MHWs in marine ecosystems. Building on research into atmospheric heatwaves, we propose both a general and specific definition for MHWs, based on a hierarchy of metrics that allow for different data sets to be used in identifying MHWs. We generally define a MHW as a prolonged discrete anomalously warm water event that can be described by its duration, intensity, rate of evolution, and spatial extent. Specifically, we consider an anomalously warm event to be a MHW if it lasts for five or more days, with temperatures warmer than the 90th percentile based on a 30-year historical baseline period. This structure provides flexibility with regard to the description of MHWs and transparency in communicating MHWs to a general audience. The use of these metrics is illustrated for three 21st century MHWs; the northern Mediterranean event in 2003, the Western Australia ‘Ningaloo Niño’ in 2011, and the northwest Atlantic event in 2012. We recommend a specific quantitative definition for MHWs to facilitate global comparisons and to advance our understanding of these phenomena.

A hierarchical approach to defining marine heatwaves

Marine heatwaves (MHWs) have been observed around the world and are expected to increase in intensity and frequency under anthropogenic climate change. A variety of impacts have been associated with these anomalous events, including shifts in species ranges, local extinctions and economic impacts on seafood industries through declines in important fishery species and impacts on aquaculture. Extreme temperatures are increasingly seen as important influences on biological systems, yet a consistent definition of MHWs does not exist. A clear definition will facilitate retrospective comparisons between MHWs, enabling the synthesis and a mechanistic understanding of the role of MHWs in marine ecosystems. Building on research into atmospheric heatwaves, we propose both a general and specific definition for MHWs, based on a hierarchy of metrics that allow for different data sets to be used in identifying MHWs. We generally define a MHW as a prolonged discrete anomalously warm water event that can be described by its duration, intensity, rate of evolution, and spatial extent. Specifically, we consider an anomalously warm event to be a MHW if it lasts for five or more days, with temperatures warmer than the 90th percentile based on a 30-year historical baseline period. This structure provides flexibility with regard to the description of MHWs and transparency in communicating MHWs to a general audience. The use of these metrics is illustrated for three 21st century MHWs; the northern Mediterranean event in 2003, the Western Australia ‘Ningaloo Niño’ in 2011, and the northwest Atlantic event in 2012. We recommend a specific quantitative definition for MHWs to facilitate global comparisons and to advance our understanding of these phenomena.

Climate driven regime shift of a temperate marine ecosystem

Ecosystem reconfigurations arising from climate-driven changes in species distributions are expected to have profound ecological, social, and economic implications. Here we reveal a rapid climate-driven regime shift of Australian temperate reef communities, which lost their defining kelp forests and became dominated by persistent seaweed turfs. After decades of ocean warming, extreme marine heat waves forced a 100-kilometer range contraction of extensive kelp forests and saw temperate species replaced by seaweeds, invertebrates, corals, and fishes characteristic of subtropical and tropical waters. This community-wide tropicalization fundamentally altered key ecological processes, suppressing the recovery of kelp forests.

Climate driven regime shift of a temperate marine ecosystem

Ecosystem reconfigurations arising from climate-driven changes in species distributions are expected to have profound ecological, social, and economic implications. Here we reveal a rapid climate-driven regime shift of Australian temperate reef communities, which lost their defining kelp forests and became dominated by persistent seaweed turfs. After decades of ocean warming, extreme marine heat waves forced a 100-kilometer range contraction of extensive kelp forests and saw temperate species replaced by seaweeds, invertebrates, corals, and fishes characteristic of subtropical and tropical waters. This community-wide tropicalization fundamentally altered key ecological processes, suppressing the recovery of kelp forests.

How Have Institutional Barriers Impacted Implementation of Ecosystem Based Fishery Management in the US

Thesis (Master's)--University of Washington, 2016-08

Antibacterial activity of the marine sponge Ircinia Campana collected at Punta Uva Limón against Staphylococcus Aureus

The sponges are simple multicellularorganisms; they inhabit in marine environments from the polar seas to the tropical waterswhere they are more abundant. These species are exposed to large populations of microbes, reason that explains their complex morphological and cellular defense mechanism, which are used by these organisms to fight against pathogens. The purpose of this study was to evaluate the antibacterial activity of the marine sponge Ircinia campana, whichinhabits in the south of the Caribbean coast of Costa Rica against  Sthapylococcus aureus gram-positive bacteria. Sampleswere collected in Punta Uva in Limónduring July of 2007. The active compounds were obtainedby extraction with acetone (crude extract); and subsequently, chromatographic extracts were obtained using fractions 1:4 hexane: ethyl acetate. The antibacterial activities of the different fractions, including the  crude extract were tested.Our results suggest a zone of inhibition of 14.60 ±0.25 mm for the crude extract and18.70±0.25mm for the most active fraction separated by chromatography. The metabolite responsible for the antibacterial activity was isolated by High Performance Liquid Chromatography (HPLC)and preliminarily characterized through ultraviolet (UV) and infrared (IR) spectroscopy.

Gulf of Carpentaria Developmental Finfish Trawl Fishery : Maximum Sustainable Yield

The Gulf of Carpentaria Finfish Trawl Fishery operates under developmental permits and harvests five main tropical snapper species. The fishery operates in eastern Gulf of Carpentaria waters and is managed by Fisheries Queensland on behalf of the Queensland Fishery Joint Authority. For the years 2004–2014, the fishery Total Allowable Commercial Catch (TACC) was fixed at 1250 t and substantially under-filled. In 2011 new stock analyses were published for the fishery. Results were presented to industry including the estimated equilibrium maximum sustainable yield (MSY) of 450 t for east Gulf of Carpentaria waters. The MSY value represented the maximum average combined species harvest that can be taken long-term; combining MSY harvests of the five main species. For the 2015 calendar year, a revised 450 t harvest quota was set for Crimson Snapper, Saddletail Snapper, Red Emperor and other Emperor species; plus a tonnage allowance for other permitted species. The revised quota tonnage represented a considerable reduction from the 1250 t set in previous years. Industry raised questions about not understanding how the MSY was arrived at and why it was less than early 1990s yield estimates. The purpose of this report is to explain the MSY estimates for east Gulf of Carpentaria waters. The 450 t MSY represents at present the best estimate available and is consistent with pre-2011 estimates.

The role of invertebrate organisms in the fishery potential of Lake Victoria

In Lake Victoria and other tropical inland water bodies, the study of secondary production has lagged behind other aquatic studies mainly because of inadequate research funding. Lack of basic scientific knowledge of such a major ecosystem component has greatly limited the understanding and management capacity of a vital regional fishery resource. This paper reviews the major roles played by various invertebrate organisms in the functioning of aquatic systems and the contribution of secondary production studies to fishery production assessment and management.

Fine tuning for the tropics: application of eDNA technology for invasive fish detection in tropical freshwater ecosystems

Invasive species pose a major threat to aquatic ecosystems. Their impact can be particularly severe in tropical regions, like those in northern Australia, where >20 invasive fish species are recorded. In temperate regions, environmental DNA (eDNA) technology is gaining momentum as a tool to detect aquatic pests, but the technology's effectiveness has not been fully explored in tropical systems with their unique climatic challenges (i.e. high turbidity, temperatures and ultraviolet light). In this study, we modified conventional eDNA protocols for use in tropical environments using the invasive fish, Mozambique tilapia (Oreochromis mossambicus) as a detection model. We evaluated the effects of high water temperatures and fish density on the detection of tilapia eDNA, using filters with larger pores to facilitate filtration. Large-pore filters (20 μm) were effective in filtering turbid waters and retaining sufficient eDNA, whilst achieving filtration times of 2-3 min per 2-L sample. High water temperatures, often experienced in the tropics (23, 29, 35 °C), did not affect eDNA degradation rates, although high temperatures (35 °C) did significantly increase fish eDNA shedding rates. We established a minimum detection limit for tilapia (1 fish/0.4 megalitres/after 4 days) and found that low water flow (3.17 L/s) into ponds with high fish density (>16 fish/0.4 megalitres) did not affect eDNA detection. These results demonstrate that eDNA technology can be effectively used in tropical ecosystems to detect invasive fish species. © 2016 John Wiley & Sons Ltd.

Variability in the growth, feeding and condition of barramundi (Lates calcarifer Bloch) in a northern Australian coastal river and impoundment

Lates calcarifer supports important fisheries throughout tropical Australia. Community-driven fish stocking has resulted in the creation of impoundment fisheries and supplemental stocking of selected wild riverine populations. Using predominantly tag-recapture methods, condition assessment and stomach flushing techniques, this study compared the growth of stocked and wild L. calcarifer in a tropical Australian river (Johnstone River) and stocked fish in a nearby impoundment (Lake Tinaroo). Growth of L. calcarifer in the Johnstone River appeared resource-limited, with juvenile fish in its lower freshwater reaches feeding mainly on small aytid shrimp and limited quantities of fish. Growth was probably greatest in estuarine and coastal areas than in the lower freshwater river. Fish in Lake Tinaroo, where prey availability was greater, grew faster than either wild or stocked fish in the lower freshwater areas of the Johnstone River. Growth of L. calcarifer was highly seasonal with marked declines in the cooler months. This was reflected in both stomach fullness and the percentage of fish with empty stomachs but the condition of L. calcarifer was similar across most sites. In areas where food resources appear stretched, adverse effects on resident L. calcarifer populations and their attendant prey species should be minimised through cessation of, or more conservative, stocking practices.

Ecoviability for small-scale fisheries in the context of food security constraints

This paper applies a stochastic viability approach to a tropical small-scale fishery, offering a theoretical and empirical example of ecosystem-based fishery management approach that accounts for food security. The model integrates multi-species, multi-fleet and uncertainty as well as profitability, food production, and demographic growth. It is calibrated over the period 2006–2010 using monthly catch and effort data from the French Guiana's coastal fishery, involving thirteen species and four fleets. Using projections at the horizon 2040, different management strategies and scenarios are compared from a viability viewpoint, thus accounting for biodiversity preservation, fleet profitability and food security. The analysis shows that under certain conditions, viable options can be identified which allow fishing intensity and production to be increased to respond to food security requirements but with minimum impacts on the marine resources.

Rising temperatures increased recruitment of brown tiger prawn (Penaeus esculentus) in Moreton Bay (Australia)

Abiotic factors are fundamental drivers of the dynamics of wild marine fish populations. Identifying and quantifying their influence on species targeted by the fishing industry is difficult and very important for managing fisheries in a changing climate. Using multiple regression, we investigated the influence of both temperature and rainfall on the variability of recruitment of a tropical species, the brown tiger prawn (Penaeus esculentus), in Moreton Bay which is located near the southern limit of its distribution on the east coast of Australia. A step-wise selection between environmental variables identified that variations in recruitment from 1990 to 2014 were best explained by a combination of temperature and spawning stock biomass. Temperature explains 35% of recruitment variability and spawning stock biomass 33%. This analysis suggests that increasing temperatures have increased recruitment of brown tiger prawn in Moreton Bay.

Harvesting and Collection of Animal Forest Species

The harvest and trade of corals and other benthic organisms from the world’s shallow tropical reefs is a lucrative industry that can have positive socioeconomic benefits for communities while supplying the increasing demand specimens for aquaria and curios. For most countries, this trade has historically been almost entirely unregulated. More recently, in response to concerns about the rapid decline of some reefs in the face of anthropogenic and natural pressures, as well as indications of depletions and even localized extinctions of some species caused by harvesting, there have been attempts to improve the sustainability of the industry. Both developing and developed countries face different impediments to this reform, the most pressing and common of which is the lack of reliable data on world trade through CITES. Thereafter, differences in the processes through which reform can be implemented are based principally on the length of the supply chain from collection to export, the degree of industry stewardship, and resourcing. The coral collection fishery in Queensland, Australia, provides an example where continual improvements in reporting and risk assessments and adopting a comanagement approach are delivering better adaptive management of the resource, although the on-ground sustainability benefits of this approach are still to be tested. A simpler approach to sustainable use of coral is to favor the replacement of wild harvested specimens with those bred or grown entirely in an aquaculture facility (as opposed to merely collected and then grown out in culture). Yet there are major impediments to this change, including the dependence of many public aquaria on the same sources as the hobbyist community, difficulties of culturing some species in captivity, and infrastructure costs. Nevertheless, this approach will likely play an important part in reef conservation efforts in the future.

An Investigation of the Impacts of Ponded Pastures on Barramundi and Other Finfish Populations in Tropical Coastal Wetlands

Objectives: 1) To document the extent of ponded pastures and other pondage systems in and adjacent to coastal wetlands on the central coast of Queensland. 2) To assess the movement, growth and survival of barramundi in ponded pastures. 3) To assess the utilisation by barramundi of ponded pastures and wetlands dominated by exotic grass species. 4) To identify appropriate wetland management strategies for facilitating barramundi movement and survival in ponded pastures and other pondage systems. 5) To document the species composition of finfish populations and their relative abundance in ponded pastures.

Diversity of decapod crustaceans at the interface of unconsolidated seabed areas and rocky shores in tropical/subtropical Brazil

The decapod crustacean assemblages from unconsolidated seabed areas located near rocky shores in the Ubatuba region on the south-east coast of Brazil were analysed by investigating the abundance, richness, diversity and dominance of species. The relationships of the sediment and bottom-water temperature to total species abundance, richness and diversity were also evaluated. Monthly samples were taken from January 1998 through December 1999 at sites in Ubatumirim and Mar Virado. At each locality, three areas were defined as either 'exposed', 'sheltered' or 'island'. The highest species abundance was found in the sheltered area of Ubatumirim and the exposed area of Mar Virado, and during autumn. At Ubatumirim, the highest richness occurred in the exposed area and the highest diversity near the island. At Mar Virado, the highest richness and diversity were found near the island. Autumn and winter collections yielded the highest richness but the lowest diversity. The higher diversities, which were measured near the islands and during spring and summer, were consequences of the greater evenness of the data. The areas with the highest diversity also had the most heterogeneous sediment composition, thus reinforcing the hypothesis that areas with more complex substrata support more diverse faunas.