Fish

Corals on Flynn Reef, part of Australia's Great Barrier Reef
Corals on Flynn Reef, part of Australia's Great Barrier Reef

Temperature and habitat changes have impacted Australia's reef fishes

For more than a decade, some researchers in Australia have been monitoring coral reefs in the vicinity to see how rising ocean temperatures affect both the tropical and temperate reef fish communities.

The findings of their study was published in the Current Biology journal.

According to lead author Rick Stuart-Smith, a marine ecologist at the University of Tasmania, the team had focused on reef fishes as reefs provided many benefits to people and the fishes there helped maintain the natural ecological function of the reefs.

Fathead minnow
Fathead minnow

Minnows can manage drastic temperature increases, study shows

Like other fish, minnows can adjust their body temperatures to match that of their surroundings.

Research into the effects of climate change on fish generally focus on their heat tolerance at an increase of two or three degrees Celsius above the current average temperatures.

However, a recent University of Illinois study wanted to find out how fathead minnows handled short-term temperature spikes—those amounting to as much as 5 to 10 degrees Celsius above average.

Seeking Eye Contact: Fish Gaze Reveals Self-Awareness

For many years, I held a weekly feeding session for the resident reef sharks and their visitors in the study area where I observed their behaviour. If I had enough shark food, I would scatter crumbs into the water for the fish after the sharks had left. The fish knew this, so they had to wait, and while they were waiting, they were excited.

Motorboat in the Caribbean
Motorboat in the Caribbean (Flickr/CC BY-NC-ND 2.0)

Coral reef fish breed better with less motorboat noise

They then followed the breeding of spiny chromis and discovered that 65 percent of nests on quieter reefs still had offspring at the season’s end, compared to 40 percent on reefs with a lot of motorboat traffic. On quieter reefs, offspring were larger, and each nest had more offspring by the end of the season.

Some juvenile fish on coral reefs exposed to motorboat noise have stunted growth and may be half as likely to survive as fish on quieter reefs, owing to the noise pollution altering their parents' caregiving behavior, said the researchers.

bonefish
Bonefish (Albula vulpes)

Study finds traces of pharmaceutical drugs in bonefish and their prey

Florida’s seagrass flats used to be the place where anglers from around the world would congregate to catch the bonefish. However, this is no longer the case, as populations of the fish—nicknamed “grey ghosts”—have fallen by more than 50 percent over four decades.

In an article published in The Guardian, according to Dr Jennifer Rehage, a fish ecologist and associate professor at Florida International University (FIU), many anglers had said they could not find bonefish in the seagrass flats anymore.

Barred Hamlet (Hypoplectrus puella)
Barred Hamlet (Hypoplectrus puella)

Causes of colour patterns in coral reef fish

The hamlets, a group of reef fishes from the wider Caribbean, sport a stunning array of colours and patterns, but the genetic basis of this morphological variety is unclear.

Although the hamlet lineage is about 26 million years old, the diversification of colours appears to have occurred only within the last 10,000 generations in a burst of diversification that ranks among the fastest in fishes.

Some of the nests that were discovered
Some of the nests that were discovered

World's largest fish breeding area discovered in Antarctica

Using a towed camera system, researchers discovered the world’s largest fish breeding area near the Filchner Ice Shelf, south of the Antarctic Weddell Sea.

The nests belonged to the Jonah’s icefish (Neopagetopsis ionah). Mapping the area suggested a total extent of 240 square kilometres. Based on the density of the nests and the size of the breeding area, it was estimated that there were about 60 million nests.

Snowflake morays can capture prey on land

Many of us are familiar with photos of moray eels snug in their caves or crevices, peering out into the open sea.

One might imagine them venturing out to hunt for prey when hunger pangs strike or an unfortunate prey swims by, but do you know that a particular species of moray eels—the snowflake moray—can hunt on dry land as well?

At least, this was what happened when a group of scientists from UC Santa Cruz filmed snowflake morays emerging out from the water onto dry land, then grabbing a piece of meat with their fangs, and swallowing it.

Sulphur mollies move in waves in response to the presence of a predator.
Sulphur mollies move in waves in response to the presence of a predator.

Sulphur mollies move in waves to evade predators

While fish are generally no match for predatory birds that hunt them from above, the sulphur molly, a freshwater fish species which can grow up to 4.5 inches, appear to have developed an effective defence mechanism.

When the school spots a potential predator (not necessarily birds, but any other species that may prove a threat, including humans), the school start swimming in waves that were conspicuous, repetitive and rhythmic.

And it is not just a few hundred sulphur mollies involved in this display—we're talking about a much larger number. 

Anemonefish sheltering in coral
Anemonefish sheltering in coral

Chemical pollutants disrupt reproduction in anemonefish

Thanks to increased awareness, we are all aware of how some plastic food utensils can leach Bisphenol-A (BPA) into our food.

BPA is an endocrine disruptor and it can interfere with how the hormones in our bodies function. Studies have shown that pollutants like BPA tend to feminize animals like freshwater fish, rats and mice. 

How does it affect animals whose gender is determined by its environment?