Evidence from genetic and Lagrangian drifter data for transatlantic transport of small juvenile green turtles

Aim  A key life-history component for many animals is the need for movement between different geographical locations at particular times. Green turtle (Chelonia mydas) hatchlings disperse from their natal location to spend an early pelagic stage in the ocean, followed by a neritic stage where small juveniles settle in coastal areas. In this study, we combined genetic and Lagrangian drifter data to investigate the connectivity between natal and foraging locations. In particular we focus on the evidence for transatlantic transport. Location  Atlantic Ocean.

Methods  We used mitochondrial DNA (mtDNA) sequences (n = 1567) from foraging groups (n = 8) and nesting populations (n = 12) on both sides of the Atlantic. Genetic data were obtained for Cape Verde juvenile turtles, a foraging group not previously sampled for genetic study. Various statistical methods were used to explore spatial genetics and population genetic structure (e.g. exact tests of differentiation, Geneland and analysis of molecular variance). Many-to-many mixed stock analysis estimated the connectivity between nesting and foraging groups.

Results  Our key new finding is robust evidence for connectivity between a nesting population on the South American coast (25% of the Surinam nesting population are estimated to go to Cape Verde) and a foraging group off the coast of West Africa (38% of Cape Verde juveniles are estimated to originate from Surinam), thus extending the results of previous investigations by confirming that there is substantial transatlantic dispersal in both directions. Lagrangian drifter data demonstrated that transport by drift across the Atlantic within a few years is possible.

Main conclusions  Small juvenile green turtles seem capable of dispersing extensively, and can drop out of the pelagic phase on a transatlantic scale (the average distance between natal and foraging locations was 3048 km). Nevertheless, we also find support for the ‘closest-to-home’ hypothesis in that the degree of contribution from a nesting population to a foraging group is correlated with proximity. Larger-sized turtles appear to feed closer to their natal breeding grounds (the average distance was 1133 km), indicating that those that have been initially transported to far-flung foraging grounds may still be able to move nearer to home as they grow larger.

Natal site and offshore swimming influence fitness and long-distance ocean transport in young sea turtles

Although long-distance transport of marine organisms is constrained by numerous oceanic and biological factors, some species have evolved life-histories reliant on such movements. We examine the factors that promote long-distance transport in a transoceanic migrant, young loggerhead sea turtles (Caretta caretta), from the southeastern U.S. Empirical data from near-surface buoys and simulations in two ocean circulation models indicated that passive drifters are often retained for long periods shoreward of oceanic fronts that delineate coastal and offshore waters. Further simulations revealed that offshore swimming aided newly hatched turtles in moving past fronts and increased turtles’ probability of survival, reaching distant foraging grounds, and encountering favorable temperatures. Swimming was most beneficial in regions that were more favorable under scenarios assuming passive drift. These results have broad implications for understanding the movement processes of many marine species, highlighting likely retention of more planktonic species and potential for dispersal in more nektonic species.

The broad-scale distribution of five jellyfish species across a temperate coastal environment

Jellyfish (medusae) are sometimes the most noticeable and abundant members of coastal planktonic communities, yet ironically, this high conspicuousness is not reflected in our overall understanding of their spatial distributions across large expanses of water. Here, we set out to elucidate the spatial (and temporal) patterns for five jellyfish species (Phylum Cnidaria, Orders Rhizostomeae and Semaeostomeae) across the Irish & Celtic Seas, an extensive shelf-sea area at Europe’s northwesterly margin encompassing several thousand square kilometers. Data were gathered using two independent methods: (1) surface-counts of jellyfish from ships of opportunity, and (2) regular shoreline surveys for stranding events over three consecutive years. Jellyfish species displayed distinct species-specific distributions, with an apparent segregation of some species. Furthermore, a different species composition was noticeable between the northern and southern parts of the study area. Most importantly, our data suggests that jellyfish distributions broadly reflect the major hydrographic regimes (and associated physical discontinuities) of the study area, with mixed water masses possibly acting as a trophic barrier or non-favourable environment for the successful growth and reproduction of jellyfish species.

High activity and Levy searches : jellyfish can search the water column like fish

Over-fishing may lead to a decrease in fish abundance and a proliferation of jellyfish. Active movements and prey search might be thought to provide a competitive advantage for fish, but here we use data-loggers to show that the frequently occurring coastal jellyfish (Rhizostoma octopus) does not simply passively drift to encounter prey. Jellyfish (327 days of data from 25 jellyfish with depth collected every 1 min) showed very dynamic vertical movements, with their integrated vertical movement averaging 619.2 m d−1, more than 60 times the water depth where they were tagged. The majority of movement patterns were best approximated by exponential models describing normal random walks. However, jellyfish also showed switching behaviour from exponential patterns to patterns best fitted by a truncated Lévy distribution with exponents (mean μ = 1.96, range 1.2–2.9) close to the theoretical optimum for searching for sparse prey (μopt ≈ 2.0). Complex movements in these ‘simple’ animals may help jellyfish to compete effectively with fish for plankton prey, which may enhance their ability to increase in dominance in perturbed ocean systems.

South west Victoria 2012-2050 : are the settlements sustainable?

Over the past few decades coastal cities around the world have grown at an incredible rate. With this growth have come major challenges relating to land use planning, social relationships, economic development, bio diversity and the ecological footprint. The following paper selects three regional coastal towns (Warrnambool, Portland and Port Fairy) situated in the Australian state of Victoria, and addresses the issues of: increasing population and population density, open space requirements, residential density issues, public transport coverage, employment and employment density, a shifting economic climate, environment and climate change, water quality issues and building energy consumption with subsequent C02 emissions. Through a series of simulations the nine issues for each of the three cities will be examined from 2012 through to 2030. The goal is to highlight the current and simulated future impacts of the selected issues and propose solutions that could mitigate those impacts.

Geochemical changes during recharge with tertiary-treated wastewater at a coastal sandfill

Results of experiments investigating geochemical changes during artificial recharge of treated wastewater at a coastal sandfill, reclaimed with sand dredged from the seabed, are reported in this paper. Laboratory batch experiments were conducted using secondary effluent (SE) and SE treated with an additional ultrafiltration process (UF), and wastewater treated by reverse osmosis (RO) process, mixed with surface sand obtained from the sandfill. Experiments with RO showed a net increase of 0.41 meq/L, 0.12 meq/L and 0.31 meq/L for Ca(2 + ), Mg(2 + ) and HCO(3) (-), respectively. UF and SE also exhibited net increase in Ca(2 + ), Mg(2 + ) and HCO(3) (-) indicating carbonate mineral dissolution. All three waters were found to be over-saturated with respect to calcite. Carbonate dissolution reactions were observed in the field experiments. However, the presence of imported clays from the borrow source gave rise to ion exchange reactions where Na(+) attached to the clay particles were exchanged for Ca(2 + ) and Mg(2 + ) inducing mineral dissolution, driven by sub-saturation conditions. This resulted in an increase in pH with maximum values in excess of 9.0. It was also found that the sodium adsorption ratio remained high (>10) even after the groundwater had been diluted sufficiently to freshwater levels (ionic strength, I <0.015) indicating a potential for the dispersion of clay particles. This could have a deleterious consequence on porosity and hydraulic conductivity.

DOC and UVA attenuation with soil aquifer treatment in the saturated zone of an artificial coastal sandfill

Results from a direct recharge experiment conducted in the field to investigate DOC and UVA(254) attenuation rates during the direct injection of UF treated wastewater into a artificial coastal sandfill are presented in this paper. Approximately 500 m(3) of ultra-filtered wastewater was injected into the saturated zone, over a period of 9 days. The movement of the plume was tracked over 80 days, during which time samples were obtained from multilevel samplers installed in transects across the drift axis of the plume. An analysis of fluorescein in the samples obtained during the drift of the UF plume showed that DOC and UVA were attenuated beyond rates predicted by conservative mixing, by up to a maximum of 45%. A degradation coefficient of 0.0175 day(-1) was found to be applicable for DOC degradation. After a drift period of 80 days, DOC and UVA reduced to approximately 4.5 mg/l and 0.100 cm(-1), respectively, from initial values of 8.06 mg/l and 0.199 cm(-1).

Implications of climate change for macrophytic rafts and their hitchhikers

Most models predicting changes to species distributions under future climate scenarios ignore dispersal processes, despite their importance in determining community structure in both terrestrial and aquatic systems ('supply-side ecology'). In the marine environment, facilitation of long-distance dispersal of coastal organisms by macrophytic rafts may be severely modified by climate impacts on raft supply, quality, and persistence, and on transport processes. Increasing storminess in the coastal zone, higher water temperatures, and changes in water circulation represent some of the key mechanisms that will directly affect rafts, while increases in herbivore metabolism due to higher water temperatures are likely to indirectly reduce raft longevity through raft consumption. Accurate predictions of climate impacts on coastal biodiversity will be con - tingent on resolution of factors influencing rafting so that this and other dispersal mechanisms can be incorporated into species distribution models. © 2011 Inter-Research.

Demo abstract: wind measurements for water quality studies in urban reservoirs

Water quality monitoring and prediction are critical for ensuring the sustainability of water resources which are essential for social security, especially for countries with limited land like Singapore. For example, the Singapore government identified water as a new growth sector and committed in 2006 to invest S$ 330 million over the following five years for water research and development [1]. To investigate the water quality evolution numerically, some key water quality parameters at several discrete locations in the reservoir (e.g., dissolved oxygen, chlorophyll, and temperature) and some environmental parameters (e.g., the wind distribution above water surface, air temperature and precipitation) are used as inputs to a three-dimensional hydrodynamics-ecological model, Estuary Lake and Coastal Ocean Model - Computational Aquatic Ecosystem Dynamics Model (ELCOM-CAEDYM) [2]. Based on the calculation in the model, we can obtain the distribution of water quality in the whole reservoir. We can also study the effect of different environmental parameters on the water quality evolution, and finally predict the water quality of the reservoir with a time step of 30 seconds. In this demo, we introduce our data collection system which enables water quality studies with real-time sensor data.

Selective, spontaneous one-way oil-transport fabrics and their novel use for gauging liquid surface tension

Thin porous materials that can spontaneously transport oil fluids just in a single direction have great potential for making energy-saving functional membranes. However, there is little data for the preparation and functionalities of this smart material. Here, we report a novel method to prepare one-way oil-transport fabrics and their application in detecting liquid surface tension. This functional fabric was prepared by a two-step coating process to apply flowerlike ZnO nanorods, fluorinated decyl polyhedral oligomeric silsesquioxanes, and hydrolyzed fluorinated alkylsilane on a fabric substrate. Upon one-sided UV irradiation, the coated fabric shows a one-way transport feature that allows oil fluid transport automatically from the unirradiated side to the UV-irradiated surface, but it stops fluid transport in the opposite direction. The fabric still maintains high superhydrophobicity after UV treatment. The one-way fluid transport takes place only for the oil fluids with a specific surface tension value, and the fluid selectivity is dependent on the UV treatment time. Changing the UV irradiation time from 6 to 30 h broadened the one-way transport for fluids with surface tension from around 22.3 mN/m to a range of 22.3-56.7 mN/m. We further proved that this selective one-way oil transport can be used to estimate the surface tension of a liquid simply by observing its transport feature on a series of fabrics with different one-way oil-transport selectivities. To our knowledge, this is the first example to use one-way fluid-transport materials for testing the liquid surface tension. It may open up further theoretical studies and the development of novel fluid sensors.

Supramolecular ionic networks with superior thermal and transport properties based on novel delocalized di-anionic compounds

Supramolecular ionic networks based on highly delocalized dianions having (trifluoromethane-sulfonyl)imide, (propylsulfonyl)methanide and (cyano-propylsulfonyl)imide groups were developed and their physical properties were examined in detail. Most of the synthesized compounds were semi-crystalline possessing Tm values close to 100°C; however, amorphous networks were also obtained using aromatic asymmetric dianions. Rheological measurements in temperature sweep tests at a constant frequency confirmed two different behaviors: a fast melting close to the Tm for semi-crystalline materials and a thermoreversible network for liquid transition for the amorphous supramolecular ionic networks. It was found that the amorphous ionic networks showed significantly higher ionic conductivity (10^-3 S cm^-1 at 100°C) than the crystalline ionic networks (10^-6 S cm^-1) and previously reported amorphous citrate ionic networks (10^-5 S cm^-1). The supramolecular ionic networks containing hydrophobic (trifluoromethanesulfonyl)imide groups demonstrated improved water stability and higher thermal stability than the previously synthesized carboxylate ones. Noticeably, the obtained amorphous supramolecular ionic networks combine not only high ionic conductivity and thermal stability, but also self-healing properties into the same material.