Happy Friday readers! On today’s episode of Ocean Talk Friday, Andrew and I deconstruct the Island Mass Effect, plea for the lives of sea stars and lobsters, and nerd out about the social behavior of octopuses.
Have you ever wondered why tropical islands can be such a paradise for biodiversity when they’re smack dab in the middle of the mostly deserted open ocean? Why are these oases such a hotspot for marine life and shorebirds, when everything around it is relatively unproductive? Well, researchers out of Hawaii recently confirmed the theory that islands’ ecological productivity stems from what is known as the Island Mass Effect (IME). The IME describes the changing physical oceanographic processes associated with the formation of islands, namely the alteration of circulation patterns. This alteration benefits many species of marine phytoplankton, whose populations abound in areas surrounding islands. Since phytoplankton are the major primary [producers in ocean ecosystems, increased levels of these plankton will attract a variety of other marine life who rely on them for food. The droppings of higher-level animals, such as shorebirds, fish, or humans, add nutrients to the surrounding ecosystem that further encourage phytoplankton growth. Therefore, the IME induces a biological feedback loop that results in relatively productive ecosystems situated in what is mostly a minimally populated open ocean environment.
Marine invertebrates have it rough out there. Invertebrates represent over 98% of animal life on earth and yet we still don’t have a week dedicated to them. Well, Andrew and I wanted to take some time today to plea for the lives of two specific groups of invertebrates, sea stars and lobsters. Over the last few years, approximately 20 species of sea stars are literally wasting away along the northeastern Pacific coasts. This “Sea Star Wasting Syndrome” is most likely caused by a virus or bacteria that proliferates in warmer waters. Because of the recent impacts climate change has had on the Pacific, we’re starting to see warmer ocean temperatures and large numbers of sea stars afflicted with this awful disease. Similarly, lobsters along the northwestern Atlantic coast have succumbed to an “epizootic shell disease” that has reduced the population and its associated fishery. While they may not have the cute and cuddly face of a sea otter or a stranded polar bear, losing these invertebrates could have drastic effects on our ecosystem and economy. The lobster fishery is a huge industry in New England, and lobsters afflicted with the aforementioned bacteria cannot legally be sold. Sea stars, on the other hand, are a keystone predator in Pacific coastal ecosystems. Their absence will trigger enormous population spikes in mussels along the rocky pacific coast, which would crowd out local biodiversity and disrupt these incredibly productive and diverse ecosystems.
If you’re like me, you spent close to 20-30 hours each week just trying to increase your chances at winning rent money at the monthly octopus fight. Well, recent research by David Scheel of Alaska Pacific University and his colleagues in Australia suggests that the common Sydney octopus (Octopus tetricus) signals to other, potentially threatening octopuses their level of aggression. For example, situations in which two individuals both present a dark body color are more likely to result in a physical confrontation, whereas interactions between one dark individual and one pale individual typically result in the pale one backing off before a fight ensues. Since these octopuses are mostly solitary and territorial, researchers previously believed their body patterns were mostly used to hide from predators. However, this study suggests that even relatively solitary cephalopods still exhibit highly complex social behavior that we are just beginning to understand.
Enjoy the Podcast!