McMeans B.C.,University of Guelph |
McCann K.S.,University of Guelph |
Tunney T.D.,University of Wisconsin - Madison |
Fisk A.T.,University of Windsor |
And 4 more authors.
Ecological Monographs | Year: 2016
Aquatic ecosystems support size structured food webs, wherein predator- prey body sizes span orders of magnitude. As such, these food webs are replete with extremely generalized feeding strategies, especially among the larger bodied, higher trophic position taxa. The movement scale of aquatic organisms also generally increases with body size and trophic position. Together, these body size, mobility, and foraging relationships suggest that organisms lower in the food web generate relatively distinct energetic pathways by feeding over smaller spatial areas. Concurrently, the potential capacity for generalist foraging and spatial coupling of these pathways often increases, on average, moving up the food web toward higher trophic levels. We argue that these attributes make for a food web architecture that is inherently 'adaptive' in its response to environmental conditions. This is because variation in lower trophic level dynamics is dampened by the capacity of predators to fl exibly alter their foraging behavior. We argue that empirical, theoretical, and applied research needs to embrace this inherently adaptive architecture if we are to understand the relationship between structure and function in the face of ongoing environmental change. Toward this goal, we discuss empirical patterns in the structure of lake food webs to suggest that ecosystems change consistently, from individual traits to the structure of whole food webs, under changing environmental conditions. We then explore an empirical example to reveal that explicitly unfolding the mechanisms that drive these adaptive responses offers insight into how human- driven impacts, such as climate change, invasive species, and fi sheries harvest, ought to influence ecosystem structure and function (e.g., stability, secondary productivity, maintenance of major energy pathways). We end by arguing that such a directed food web research program promises a powerful acrossscale framework for more effective ecosystem monitoring and management. © 2016 by the Ecological Society of America.
News Article | January 29, 2017
The Grass carp one of the four Asian carp species has reportedly entered the great freshwater lakes of Michigan, Erie and Ontario. The invasion of Grass carp poses a serious threat to the lake's aquatic environment reveals a scientific study. Grass carp is an herbivorous fish found in freshwaters which can weigh a maximum of 90 lbs. It is not a naturally occurring fish in U.S. and Europe. The Grass carp was first cultivated in early 1960s in the U.S. to control growth of weed in the waterways. Some escaped through the system and went north, gradually settling down in the Great Lakes. This is not the first time the invasive fish has been spotted in the great lakes. Bighead Grass carp and Silver Grass carp are most feared in the aquatic ecosystem as they feed on microscopic plants and animals in huge quantities. Grass carp as a species is considered to be the most invasive of all fishes and they pose a threat to other fishes in the lakes. Why? As Grass carps "aggressively outcompete" native fish for food and are capable of eventually overtaking the particular aquatic ecosystem. A report has been prepared by American and Canadian experts with help from Fisheries and Oceans Canada, the U.S. Fish and Wildlife Services and the Great Lakes Fisheries Commission, which states that 9 out of 10 Grass carp caught between 2013 and 2016, were found to be fertile. It is believed that the fertile fish were not born in the Great Lakes and eventually made their way into Canada. "Grass carp have been in the Great Lakes for ... probably 30 years or even more but they've been sterile, lately ... we've been seeing recurring incidents of fertile grass carp in the Great Lakes. They're not supposed to be fertile," said Mark Gaden from Great Lakes Fishery Commission. They are known to reside the freshwater lakes for quite some time "humming in the background." Most of these fish were sterile, thus the question of invasion and risk to the ecosystem never arose. However, in recent years, the concern has been growing as more and more fertile Grass carps are being captured. Grass carps reared in hatcheries in some states have to be sterile before they are released into water. "Right now, the sterile fish outnumber the fertile fish. This isn't game over, but we are finding more of these fertile fish," said Becky Cudmore, primary author of the study. The study's analysis points out that Grass carp will eventually become "established" in the lakes of Erie, Huron, Michigan and Ontario in 10 years unless serious action is taken. To reach an established population, the specie has to reproduce over multiple generations. Several options like strict laws regarding bringing Grass carp in the region, along with prevention of release of fertile fish, may help control the alarming situation. Also, nets can be used to block the fish's course to spawning areas during the time of reproduction. "Our assessment is saying that yes, they were showing up before, but now they're starting the invasion process. They have arrived. Now is the time to act," noted Cudmore. Â© 2017 Tech Times, All rights reserved. Do not reproduce without permission.