Posts

Quiet Oceans

Image
H. ampullatus , the Northern bottlenose Whale As pointed out in one of the most important papers for marine science in decades (Duarte et al. 2020), during World War I and  II, an unexpected benefit was observed: Fish populations rebounded after fishing boats were withdrawn from the oceans. The hiatus allowed fish stocks to replenish, likely delaying their collapse by decades.  This recovery of marine life demonstrates the resilience within these communities. There is hope for the ocean yet.    Did COVID create a similar situation? It turns out that the slowdown in shipping and ocean traffic generally quieted the oceans. What effects did this quieting have on overall ocean ecosystems?   In areas like the Hauraki Gulf Marine Park in New Zealand, boat traffic almost completely stopped, and underwater noise dropped by about 2/3 within 12 hours . This  reduction expanded the communication ranges of fish and dolphins by up to  65% . Dolphins' calls can trav...
Post a Comment
Read more

Death comes to the Amazon

Image
 Death comes to the Nile Amazon Amazon River Dolphin (modified from Scientific American). Hot temperatures are again hitting the Amazon River and its tributaries. In 2023, temperature spikes in and around Lago Tefé killed hundreds of river dolphins. Tefé is located in the heart of Amazonas, approximately 400 miles up the Amazon River from Manaus, the capital of the region. As a whole, the region is sparsely populated, as Manaus is one of the two cities that have a large population of over 1 million.  Once again, temperatures are rising, and combined with regional droughts, this has created another deadly zone. In November, the lake's waters reached 41 degrees Celsius (105.8 degrees Fahrenheit). David Hannah said, "Drought conditions often coincide with high atmospheric temperatures, and such trends will become more intense and frequent with climate change." Additionally, droughts have lowered the lake levels, leading to new problems. The issue extends beyond just one lak...
Post a Comment
Read more

Have a Heart

Image
  Figure 1. Shark Heart (author's original image) Hearts have been on my mind lately.    We, humans that is, of course, have a four-chambered heart. We have two atria and two ventricles. The right side carries blood low in oxygen, and the left side, having just returned from the lungs, carries blood high in oxygen. We share this heart anatomy with the other mammals, birds, and crocodiles.    Found in most amphibians and some reptiles is a three-chambered heart with two atria and one ventricle, which allows mixing of oxygenated and deoxygenated blood. That is a bit freaky in my view: oxygenated blood and deoxygenated blood mix in the central chamber; whoever thought this was a good design?    Most animals in the kingdom do not have hearts with 3 or 4 chambers. The most speciose vertebrates, scaly fishes, have a two-chambered heart. Suppose we follow the blood flow in 18-spined sculpin (AKA long-horned sculpin),  Myoxocephalus octodecimspinosus...
Post a Comment
Read more

Northern Movements

Image
  Dusky Shark (from Blueplanetarchive.com) A recent science paper noted Dusky Sharks feeding on Gray Seals off Cape Cod.  The Dusky Shark, Carcharhinus obscurus , is a subtropical to temperate species that roams further north during the warm months; it is not known to enter the icy northern waters north of the Gulf of Maine. Expectably, they tend to be rare north of the New England coast. That was then; this is now. We have already entered a new world of warming.  Dusky Sharks can grow to be quite large, reaching lengths of over 3 meters, or more than 10 feet. They are feeders on fish, lots of fish, and will, apparently, also go in for those nice succulent seals. Thisis not something they were thought to feed on much. However, those cheeseburgers dotting the coastline, hauling out on rocks, must be a pleasant sight for a hungry shark.  The abundance of seals makes them a central target for shark species. These marine mammals are abundant in late August all along the ...
Post a Comment
Read more