Problem Statement Gracilaria vermiculophylla a newly arrived invasive

Problem Statement Gracilaria vermiculophylla, a newly arrived invasive macro algae has been introduced into Southern Beaufort County estuaries. As an invasive species, it has the potential for negative community impacts such as competitive displacement of other macroalgae, and other native symbionts and increased mortality of Diopatra cuprea. As a newly introduced species its presence may have a significant effect on the carbon budget including competitive fixation of CO 2 as well as O 2 consumption during degradation.

Hypothesis Statements �The current presence of Gracilaria vermiculophylla has increased carbon fixation levels per meter squared, which prior to this study has not been quantified. �That Gracilaria vermiculophylla is physically displacing most other symbionts in the intertidal zone, along with negatively effecting Diopatra cuprea populations. �That there is a distinct pattern of Gracilaria vermiculophylla density along the intertidal gradient.

Methods �Carbon Fixation: Quadrat sampling with recording of quantity of Gracilaria vermiculophylla plumes per quadrat. NPP estimated by measuring of ash free dry weight per quadrat. �Symbiont Displacement: Quadrat sampling of Diopatra cuprea tube caps. Recording of type of symbionts attached per tube cap. �Distinction of Densitiy patterns: Quadrat sampling and recording of amount of Gracilaria vermiculophylla plumes found per quadrat across the intertidal gradient.

Diopatra Cuprea Density Hilton Head Plantation High 1 * Low 1 0. 001400884 High 2 0. 285843434 * Low 2 Low 1 High 2 0. 001400884 * 0. 285843434 * * * 0. 000320071 0. 000003435 Low 2 * 0. 000320071 0. 000003435 * 1 and 2 are indication of separate sampling dates Comparison of densities by dates (t-test, P= 0. 05 n ≈ 15) There are significantly more Diopatra cuprea found in high density areas than low density areas. There is a significant temporal change in low density plots however there is no significant temporal change in high density plots.

Gracilaria vermiculophylla Density Hilton Head Island High 1 * Low 1 0. 000674 High 2 0. 154991 * Low 2 Low 1 High 2 0. 000674 * 0. 154991 * * * 0. 009209 0. 000003 Low 2 * 0. 009209 0. 000003 * 1 and 2 are indication of separate sampling dates Comparison of densities by dates (t-test, P= 0. 05 n ≈ 15) There is a significant spatial difference between high and low densities plots. There is a significant temporal difference in low density plot areas but there is no significant temporal difference between high density plot areas.

Gracilaria vermiculophylla Carbon Fixation Hilton Head Island High 1 * Low 1 0. 00514103 High 2 0. 04187572 * Low 2 Low 1 High 2 0. 00514103 * 0. 04187572 * * * 0. 00003037 0. 0000271 Low 2 * 0. 00003037 0. 0000271 * 1 and 2 are indication of separate sampling dates Comparison of densities by dates (t-test, P= 0. 05 n ≈ 15) High density plots have significantly more carbon input than low density plots showing a significant spatial difference. Carbon fixation also increases temporally in high and low density plots.

Diopatra cuprea Density Parris Island High 1 * Low 1 0. 0000527 High 2 0. 909780 * Low 2 Low 1 High 2 0. 0000527 * 0. 909780 * * * 0. 000003 0. 251224 Low 2 * 0. 000003 0. 251224 * 1 and 2 are indication of separate sampling dates Comparison of densities by dates (t-test, P= 0. 05 n ≈ 15) There is a significant temporal difference between low density plots, there is no significant temporal difference between high density plots. There was a significant spatial difference between the high and low density plots in the earlier sampling but there was no significant spatial difference between the high and low densities plots on the later, second sampling later in the season.

Gracilaria vermiculophylla Density Parris Island High 1 * Low 1 0. 0000500 High 2 0. 225684661 * Low 2 Low 1 High 2 0. 0000500 * 0. 225684661 * * * 0. 0000032 0. 2575238 Low 2 * 0. 0000032 0. 2575238 * 1 and 2 are indication of separate sampling dates Comparison of densities by dates (t-test, P= 0. 05 n ≈ 15) There is a significant temporal difference between low density plots, there is no significant temporal difference between high density plots. There was a significant spatial difference between the high and low density plots in the earlier sampling but there was no significant spatial difference between the high and low densities plots on the later, second sampling later in the season.

Gracilaria vermiculophylla Carbon Fixation Parris Island High 1 * Low 1 0. 000387557 High 2 0. 0000644 * Low 2 Low 1 High 2 0. 000387557 * 0. 0000644 * * * 0. 0000009 0. 000002 Low 2 * 0. 0000009 0. 000002 * 1 and 2 are indication of separate sampling dates Comparison of densities by dates (t-test, P= 0. 05 n ≈ 15) High density plots have significantly more carbon input than low density plots. Carbon fixation also increases temporally.

0 Diopatra 1 Gracillaria 2 Illyanassa 3 Ulva 48/21/2010 Obelia 450 400 350 300 250 200 150 100 50 0 Symbionts 450 400 350 300 250 200 150 100 50 0 0 Diopatra 1 Gracillaria 2 Illyanassa 3 Ulva 45/1/2010 Obelia 1& 1& 4 2& 1& 3 2& 1& 4 1& 3& 2& 4 3 2 1& 4 1& 3 2 1 6/12/2010 0 3 1& 1& 4 2 1& &3 2 1& &4 1& 3& 2& 4 3& 4 1& 2 1& 4 3 2 1 6/12/2010 Symbiont quantity High Density Quadrat Comparison HHI 0 Diopatra 1 Gracillaria 2 Illyanassa 3 Ulva 5/1/2010 4 Obelia 0 Symbiont Quantity Low Density Quadrat Comparison HHI 450 400 350 300 250 200 150 100 50 0 1& 1& 4 2& 1& 3 2& 1& 4 1& 3& 2& 4 3& 4 1& 3 4 1& 2 3 2 4 1& 2 1& 3 1& 1& 4 2& 1& 3 2& 1& 4 1& 3& 2& 4 3 2 1 1 9/18/2010 0 9/18/2010 Symbiont Quantity High Density Quadrat Comparison PI 0 Diopatra 1 Gracillaria 2 Illyanassa 3 Ulva 48/21/2010 Obelia 450 400 350 300 250 200 150 100 50 0 0 Symbiont Quantity Low Density Quadrat Comparison PI Symbionts

Conclusion � There is a significant spatial difference between high and low density plots that is most likely related to quantity of Diopatra cuprea tube caps that are available for attachment. This is most likely related to inundation periods. � There is a significant temporal difference between low density plots that is most likely related to the growth cycle of Gracilaria vermiculophylla. � There are significant spatial and temporal increases in carbon fixation that is most likely related to its increased growth in the lower intertidal zone and it’s summer temporal growth pattern.

Discussion � The significant spatial increase in carbon fixation is most likely related to the significant increase in spatial difference between high and low density plots. Gracialaria is spreading rapidly over these two areas and greatly increasing it’s coverage density and mass. Areas which before were not covered at all by any symbiot are now completely covered by Gracilaria, leading to an increase in carbon fixation. The significant temporal increase in carbon fixation is most likely related to the summer growth period of Gracilaria as well. As plumes become larger they have greater mass leading to an increase in carbon fixation when this mass is dislodged from its host. � The significant temporal difference observed between low density plots is most likely related to the summer growth pattern of Gracilaria. Most macroalgea experience a higher growth period during the summer, from an increase in light availability and warmer temperatures in the summer than in the winter. This leads to greater plume sizes and higher attachment rates. The sampling at PI showed no significant temporal difference between high density plots but I believe this was due to the size of the mass upon the first sampling. The area was already so densely covered that there was no way to increase coverage. The lack of a significant difference spatially from the second sampling I believe is because the high and low density areas both had a great amount of coverage. Quadrats only varied by a small amount of tube attachment, the low density areas were almost as densely covered as the high density areas.

� The significant spatial difference between high and low density plots is most likely related to tube availability. High density areas have more Diopatra tubes available for attachment. The lower intertidal zone which is the higher density area experiences longer inundation periods. This may lead to better and longer feeding periods for the Diopatra. This area also does not receive the high wave action that the higher intertidal zone area in which is the lower density area. This increase in hydro dynamic forces may be removing tube caps more frequently than the low density area leading to an even greater reduction in Diopatra population there fore reducing the number of Gracilaria plumes. Works Cited � Kaiser, M. et al. (2005) Marine Ecology: Processes, Systems, and Impacts. Oxford.

Future Studies �Hydro dynamic scouring and effects from Gracilaria. �Is Gracilaria acting as a refuge for other organisms? �Further interactions between Gracilaria and Diopatra.