Gobies Revisited (now with Watersnakes!)

After last week, you are probably thinking one thing: “what about these gobies?”

Last week Ferrebeekeeper featured a post on the invasive round gobies from the Black Sea which have showed up in the Great Lakes.  The blobtastic little fish sneaked into the lakes by means of ballast water carried across the great oceans in international freighters and now they are wrecking up the place.   The gobies are outcompeting larger fish for resources.  They are devouring native mussels.  To quote the USGS website, “This species has been found to prey on darters, other small fish, and Lake Trout eggs and fry in laboratory experiments. They also may feed on eggs and fry of sculpins, darters, and Logperch (Marsden and Jude, 1995) and have also been found to have a significant overlap in diet preference with many native fish species.” Particularly hard hit are mottled sculpins, little round pebble-looking native fish which occupy(ied?) the ecological niche which the gobies are now taking over.  the fish horror stories contain some rather sad anecdotes of gobies biting sculpins and chasing them away and taking their lunch money and otherwise bullying them on the lake bed.  It is a rough world out there.

This mottled sculpin looks disgruntled

So are we just fated to dwell in a gobified dystopia from now on?  Well, actually, there are some positive things which the gobies are accomplishing and not everybody is sad they are here.  I was joking about gobies eating zebra mussels, the horrible invasive freshwater mussels which are filling up the Great Lakes and causing havoc to power plant and shipping infrastructure, however, it turns out the gobies do happily eat zebra mussels.  Additionally the gobies are not just eating other animals: they are also being eaten by them.  Because of the proliferation of round gobies, the previously endangered Lake Erie water snakes (Nerodia sipedon insularum) have become more prolific in number and the snakes are much fatter and happier (insomuch as we have records for these reptilian parameters).  The water snakes have been so successful at hunting gobies that they have been removed from the endangered species list (back before the act was watered down). 

Why, here’s a great writing mass of ’em! The world is getting better!

Larger gamefish like walleye, yellow perch, and bass and are eating the gobies, as are piscivorous birds like gulls, cormorants, plovers, and bald eagles(!).  Unfortunately there is downside to this as well.  Zebra mussels filter decaying cladophora algae out of the water.  This algae contains C. botulinum, a bacteria which contains the infamously dangerous botulism toxin.  If the predatory birds eat too many gobies they can be killed by the botulism and several mass die-offs have occurred.

What is the point of all of this (other, than, you know, the fact that it is happening in the world)?  I suppose this article is really about ecosystems–the complex webs of life we depend upon.  they are fragile in unexpected ways and resilient in unexpected ways.  We need to think about them more and learn more about them (witness what happened in all of my aquariums).  Thanks for the mindfulness lesson, ugly invasive goby!

 

 

Advertisement