Nov
23

After first showing up in the southern United States in the early 1990’s, the Daphnia lumholtzi, an invasive aquatic species, has now spread north into Lake St. Clair says Claudiu Tudorancea, whose research was funded by the Aquatic Invasive Species program of Fisheries and Oceans Canada.  A total of 41 Daphnia lumholtzi were recovered from Lake St. Clair.  Of the 41 specimen caught, 39 were females and two were males.  Of the 39 females, three were carrying eggs.  This is important because it demonstrates that the Daphnia lumholtzi are reproducing successfully in Lake St. Clair.  Very little information is known about the Daphnia lumholtzi, but more importantly, very little is know about the ecological effects caused by the Daphnia lumholtzi.  Scientists do speculate that Daphnia lumholtzi could harm larval and juvenile fish by lower the zooplankton available for these fish.  However, more research needs to be conducted to support this claim.

Journal of Great Lakes Research. Volume 35, 2: 313-316 (2009)

Nov
23
Filed Under (Uncategorized) by Michael Shaughnessy on 23-11-2010

Discrete and Continuous Dynamical Systems Series B 12: 2 p. 481-493 (2009)

Since its invasion to North America in 1991, Daphnia lumholtzi has continuously competed with the native Daphnia species.  The long spines characteristic of D. lumholtzi prevent the water flea from being a suitable food source for young fish.  As a result, they outcompete other Daphnia species.  This could cause larger scale problems through the disruptions of food chains.  Hao Wang out of the Georgia Institute of Technology monitored the competition between D. lumholtzi and the native D. pulex.  Four tanks were set up: tank with only D. pulex, one with only D. lumholtzi, one without Daphnia as the control and one with both species.  They were subjected to two different light sources, one of high intensity and one of low intensity.  The results showed that D. lumholtzi was more competitive at higher light intensity while D. pulex was more competitive at lower light intensity.  The researchers conclude that this study could lead to predictive assumptions of future invasion.

Nov
22
Filed Under (Uncategorized) by Drew Van Orden on 22-11-2010

Journal of Plankton Research. Volume 23: 425-433, 2001.

The success of an invader relies on the ability of that species to adapt to its new surroundings. One key factor that has a large effect on an aquatic species ability to populate new waters is temperature. In areas such as the northeastern United States, higher water temperatures during the late summer months cause a decline in some species of zooplankton. In 2001, a study investigated the effect water temperature has on Daphnia lumholtzi.

The test took place in a Kansas reservoir. Daphnia lumholtzi from the reservoir were collected for the test, and the temperature of the water was taken from the top .25 m during the collection. Daphnia lumholtzi was only found in the water between the months of July and September, when the water temperature was between 25 and 30 degrees Celsius. From this data, researchers were able to conclude that when water temperature was over 25 degrees Celsius, Daphnia lumholtzi were able to outcompete other plankton species, but did not thrive under lower temperatures. This data can be applied broadly because the it doesn’t allow the invasive species to populate regions with colder waters or dominate certain areas year round.

Nov
22
Filed Under (Uncategorized) by Kevin Ge on 22-11-2010

Journal of Great Lakes Research. Vol. 35: 313-316, 2009.
 
Originally from Australia, South East Asia, and Africa, Daphnia lumholtzi arrived in southern United States in 1991. Since then, the population has begun to spread North and more recently have reached the Laurentian Great Lakes through ballast water discharge. The spread of this tropical species in the temperate great lakes has aroused the scientific community and led to nationwide studies.

Claudiu Tudorancea, Aquatic Bioservices, Kelly Bowen and Jocelyn Gerlofsma, Great Lakes Laboratory for Fisheries and Aquatic Sciences, worked together to research the spread of D. lumholtzi in the Great Lakes. They established 10 sampling stations and found D. lumholtzi in a warm, turbid, nutrient rich area near a sea wall. Other studies had similar results, and concluded that D. lumholtzi are prominent in areas with high temperatures during warmer seasons. From their data and trends of other studies, the team concluded that warm, shallow embayments are suitable for D. lumholtzi and that if climate change predictions are correct then D. lumholtzi spread will continue.

Nov
22
Filed Under (Uncategorized) by Cole Arora on 22-11-2010

Oecologia 116, 556-564 (1998)

Although many animals possess permanent structures to deter predation (e.g., porcupines, sea urchins, and sticklebacks), others develop defensive mechanisms only in response to predator-related cues.  Daphnia Lumholtzi, a species of zooplankter that exhibits extreme “cyclomorphosis” (or changes in body shape) with a large helmet and long tail spine, is a particularly successful case in point.  Spines make prey difficult to handle by increasing the effective cross-sectional diameter of prey, thereby restricting gape-limited predators such as planktivores.  In addition to its spines, D. lumholtzi also has lateral fornicles and is virtually transparent. Given its relative size, these numerous antipredatory defenses seem extreme, but are likely related to high predation pressure in its native ecosystems.  Yet given its role as an invader, the pertinent question is whether or not that same pressure exists in ecosystems that play host to its invasion.

Kolar and Wahl (1998) examined selectivity for D. lumholtzi (relative to a control, D. pulex) by juvenile bluegill in the laboratory and field. It was found that bluegill consumed more D. pulex on average than D. lumholtzi when the species were presented alone.  That is, when the daphnids were offered together in equal numbers, bluegill selected against D. lumholtzi. Bluegill foraging behavior helps to explain the observed nonrandom feeding.  Essentially, bluegill capture efficiency foraging on D. pulex was high (85-100%) and handling times were low (usually too short to detect); predation was an effectively linear sequence consisting of orientation, attack, capture, and ingestion. Conversely, efficiencies were lower (40-96%) and handling times were longer (1-3 s) when foraging on D. lumholtzi.  Because spending such large portions of time attempting to swallow prey that could be spent foraging incurs negative energetic consequences for fish, bluegill showed avoidance behavior in their selection; that is, after successive unprofitable attempts, the bluegill would begin orienting toward and then rejecting D. lumholtzi more often than striking. Thus, the tactic of frustrating planktivores with such defenses demonstrates the ability of zooplankton morphology to deter fish predators.

Nov
21
Filed Under (Uncategorized) by Max Castillo on 21-11-2010
Discrete and Continuous Dynamical Systems Series B 12(2), 481-493(2009). doi: 10.3934

In 1990, Daphnia Lumholtzi was introduced to the United States and rapidly established itself as an aquatic invader by out competing native zooplankton for resources. As a result, native fish populations suffer because D. Lumholtzi is inedible for many species due to its spiny structure.

Kao Wang of the Georgia Institute of Technology and Katherine Dunning (among others) of Arizona State University conducted a study to see how light levels affected D. Lumholtzi populations. The team tested the invasive D. Lumholtzi and the native D. Pulex in two different light treatments and found that D. Lumholtzi consistently out competed the native species in the high light treatment, and vice versa in the low light treatment. From these results, the team created models exhibiting the “chaotic coexistence” of the Daphnia species. Using this, Wang et al. (2009) say that it may be possible to develop strategies which may control the spread of D. Lumholtzi.

Nov
21

Hydrobiologia 405, 11-23 (1999)

 Daphnia lumholtzi is an aquatic zooplankton, indigenous to Africa, Southern Asia, and Australia that has invaded and disrupted US water systems since 1991. Kirsten Work and Moshe Gophen with the University of Oklahoma Biological Station investigated variables in Lake Texoma in an attempt to understand the distribution patterns of this zooplankton species. Weekly samples of zooplankton and phytoplankton, as well as water column temperature, dissolved oxygen, conductivity, and water transparency at different water depths were recorded over a one-year period beginning in 1994. The collecting stations were chosen based on the different characteristics of water flow and water chemistry.

 The duration of D. lumholtzi in this lake suggests the successful invasion of this species. Although this looks bad for the ecosystem, their research shows that this invasive species does not compete with the native zooplankton.  This discovery suggests that both the invaded and native species could possibly coexist in Lake Texoma.  However, there still is concern on the presence of the invasive species having an indirect effect on other aspects of the lake’s ecosystem, and should therefore be monitored.

Nov
21
Filed Under (SW11) by Blair Ballard on 21-11-2010

J Arizona Nevada Acad Sci 34(2), 89-93 (2002)

Daphnia lumholtzi is an invasive zooplankton that was introduced into the U.S. in 1990. It damages ecosystems by outcompeting native zooplankton. In turn, this can deprive smaller fish of food, because many cannot ingest D. lumholtzi due to its spiny skeleton.

Dean R. Dobberfuhl of St. Johns River Water Management District and James J. Elser of Arizona State University examined the effect of D. lumholtzi on production rates of D. pulex (a native zooplankton). The experiment showed that isolated D. lumholtzi and D. pulex had higher production rates than when the two species were combined. However, the D. pulex production rate was significantly higher. Overall zooplankton production in the mixed environment was less than 50% of the D. pulex production when isolated. This suggests that the introduction of D. lumholtzi can have detrimental effects to both native zooplankton and planktivorous fish.

Nov
21
Filed Under (Uncategorized) by Stefan Cafaro on 21-11-2010

Daphnia Lumholtzi, more commonly referred to as the water flea, is a cladoceran aquatic species that is native to tropical lakes throughout east Africa and east Australia. This species was deemed an invasive animal when it was first detected throughout the southern regions of the North American continent in 1990.

Professor John H. Havel and Jennifer L. Graham, of Missouri State University, decided to determine the population overlap between Daphnia Lumholtzi and native Daphnia throughout southern regions of the United-States. These two professors collected zooplankton samples from 171 different reservoirs and lakes throughout the southern states. They found that Daphnia Lumholtzi, as well as a number of other different species of Daphnia, was found in abundance throughout many of these lakes. Havel and Graham also reported that the population of Daphnia Lumholtzi in each body of water peaked during the months spanning between July and September when the water temperature would be the highest. However, they also reported that the population of native Daphnia peaked when water temperature was cooler, specifically during the months of early spring.

Havel, H. John and Graham, L. Jennifer. “Complementary Population Dynamics of exotic and native Daphnia in North American Reservoir Communities”  Arch. Hydrobiology. Vol 167: 1-4 (245-264)

Aug
23
Filed Under (intro) by Sandra on 23-08-2010

Welcome to Aquatic Invasive Species!  I’ve asked each of you to introduce yourself to your classmates for your first blog entry.  The purpose of this informal, ungraded post – aside from getting to know each other – is to figure out the basics of WordPress.  Please attempt the following on your own:   (1) access the blog dashboard, (2) create a post, (3) edit a post, (4) comment on your peers’ entries, and (5) insert a hyperlink into the text of a post.  Don’t worry if you can’t figure out any of these tasks.  Bring your concerns to class on Wednesday and we’ll have a group trouble-shooting session.

Now for your professor’s introduction!  I’m Sandra Cooke and I’m happy to call Durham home, though I was born and raised in Silver Spring, MD.  My scholarly interests include the ecology of ultraviolet radiation and, of course, aquatic invasive species (specifically Asian carp and the water flea Daphnia lumholtzi).  My non-scholarly interests include running, traveling, and cooking.  I look forward to working with all of you this semester!