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Ocean Research

2015:  JAN | FEB | MARCH

March 2015 Issue

Sticklebacks Inherit Adaptability To Warmer Waters
Researchers at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have shown that three-spined sticklebacks in the North Sea pass on environmental information to their offspring, without genetic changes. This could play an important role in the species’ ability to adapt to the effects of climate change, reports a study in Functional Ecology.

For the North Sea, a habitat for three-spined stickleback, climate models predict a rise in mean summer water temperatures from 17° to 21°C by the year 2100.

Researchers kept female and male sticklebacks in either 17° or 21°C water for their experiments. After two months, the fish were mated within and between their acclimation temperatures. The offspring were subsequently raised in 17° or 21°C water. After 30 days, offspring that grew in water with the same temperature as their mothers displayed the best growth rates.

Offspring that live in the same conditions as their mothers showed an optimized metabolism. Through her mitochondria, the mother shares information on the environment with her offspring, which produces a lasting effect. This mechanism works particularly well in less favorable environments, which for sticklebacks means warmer waters.

Hopkins’ Rose Nudibranch Could Signal Warming Climate
The warm ocean temperatures that brought a green sea turtle to San Francisco in September and other southern species north of their usual ranges on the Pacific Coast have triggered a population explosion of a bright pink, inch-long sea slug in tide pools along the central and northern California coast.

The Hopkins’ Rose nudibranch (Okenia rosacea) is common to southern California but found only sporadically in central California and rarely north of San Francisco. However, in the past few weeks, researchers from University of California Santa Barbara (UCSB), University of California Santa Cruz, the Bodega Marine Laboratory and the California Academy of Sciences have reported densities of up to dozens per square meter in tide pools from San Luis Obispo to Humboldt counties. These are the highest numbers and northernmost records of this species seen since the strong El Niños of 1998 and 1983.

But there is currently no El Niño. The current population bloom of Hopkins’ Rose is similar to the one on the central coast in 1977, which occurred also during a weak El Niño and coincided with a major climate shift in the eastern Pacific Ocean. This triggered range deviations in numerous coastal species. Fluctuations in the abundance of intertidal adults of Hopkins’ Rose and other nudibranchs in central California were driven by regional oceanographic influences on currents and larval recruitment, researchers argued. They predicted high recruitment of these nudibranchs when warm temperatures, northward-directed currents and weak upwelling occur—which is what is happening now.

Because Hopkins’ Rose nudibranchs are fast-growing, live for a year max and move little as adults, they are potentially useful in tracking relatively rapid changes in ocean conditions. They might currently be signaling another major climate shift from cold to warm.

Slope Found to Lower Europe’s Sea Level
The U.K. National Oceanography Centre (NOC) has discovered that a slope on the ocean surface in the Strait of Gibraltar is lowering the sea level in Europe by 7 centimeters. This research, which was published by Geophysical Research Letters, will help to more accurately predict future sea levels by providing a more complete understanding of the factors that control it.

The rotation of the Earth causes ocean currents in the northern hemisphere to slope as they flow, with a low in the sea level on their left hand side. A current of water, equivalent to four Amazon rivers, is flowing into the Mediterranean from the Atlantic, returning below the surface. This surface flow means that sea level must drop to the north, across the Strait of Gibraltar.

Researchers were able to discover a simple relationship between the drop in sea level and the strength of flow of the ocean current. This relationship suggested that the sea level in Portugal should be about 7 centimeters lower than that on the Moroccan coast. With the help of new satellite gravity measurements, from the European Space Agency’s GOCE satellite as well as the NASA/DLR GRACE satellite, researchers measured this sea level drop. The gravity field measured by these satellites provides data on where the sea surface would be if no slopes existed in the ocean. By comparing this with the actual sea surface level, measured using satellite altimetry and tide gauges, it was possible to estimate the drop in sea level caused by the swirling currents.

Sulfate-Breathing Microbes Can Break Down Carbon
Two miles below the surface of the ocean, researchers have discovered new microbes that breathe sulfate. The study was published by Frontiers in Microbiology. The microbes, which have yet to be classified and named, exist in massive undersea aquifers. About one-third of the Earth’s biomass is thought to exist in this largely uncharted environment.

Researchers from the University of Southern California and the University of Hawaii took their samples from the Juan de Fuca Ridge (off the coast of Washington state). Circulation Obviation Retrofit Kit observatories created a seal at the seafloor, allowing scientists to deploy instruments and sampling devices down a borehole while keeping ocean water out. Samples were then shuttled to the surface by remote-controlled undersea vehicles or “elevators”—balloons that drop ballast and float samples gently up to the waiting scientists.

The microbes in the undersea aquifers can use sulfate to break down carbon from decaying biological material that sinks to the sea bottom and makes its way into the crustal aquifer, producing carbon dioxide.

Learning how these new microbes function will be important to getting a more accurate, quantified understanding of the overall global carbon cycle, which is currently being disrupted by man-made carbon dioxide emissions.

2015:  JAN | FEB | MARCH

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