Or Export of Secondary Production in Ecosystems

BECAUSE MOST OF THE PRODUCTIVITY AND ENERGY IS IN PLANTS & VERY LITTLE IS IN ANIMALS, ANIMALS CAN’T BE IMPORTANT IN STRUCTURING ECOSYSTEMS. RIGHT?

Kitchell et al BioScience 29: TransformationTranslocation TWO ROLES OF ANIMALS

WHY MIGHT TRANSLOCATION BE CONSUMERS IMPORTANT? Mobility and behavior of animals can cause substantial and rapid redistribution of nutrients. They can readily cross physical mixing boundaries, such as temperature or salinity stratification. They often make migrations that cross ecosystem boundaries. They are TASTY bits that enter foodwebs

EGGS LARVAE JUVENILE ADULT ESTUARY 0-age year class 1, 2, 3 age year class OCEAN ECOSYSTEM BOUNDARY MENHADEN

MASS BALANCE The mass of how many larvae entering the estuary equals the mass of one juvenile leaving the estuary? EnteringLeaving

NET EXPORT IS A FUNCTION OF: TIMING OF MIGRATION When do they cross the ecosystem boundary compared to growth and mortality? GROWTH RATE Increase in size of individual TIME MORTALITY RATE How many are there? TIME (OR SIZE)

ENTERING LEAVING GROWTH AND TIMING

MASS BALANCE Net Flux = exit-enter (# juv. exit) x (mass one juv. )*(Conc Juv ) - (# larvae enter) x (mass one larvae)*(Conc Larvae ) 0 = (1 juvenile) x (mass)*(C J ) - (? larvae) x (mass)*(C L ) Break even number is the number of larvae entering that exactly balance one juvenile leaving = Net flux of zero ? Larvae = (1 juvenile) x (mass)x (C J ) / (mass)*(C L ) Net Flux = Zero / Breakeven # =( ) x (% N J )

ENTERING LEAVING

EXPORT FROM ESTUARIES TO OFFSHORE ECOSYSTEM

Seagrass Offshore Reefs Big Bend Seagrass 3000 km 2 of seagrass High primary production Exports: Lots and Lots of Pinfish Leave and most do not return Northeastern Gulf of Mexico Lower primary production High fishery yields An Ecosystem Subsidy

SEAGRASS Shallow/Deep Reefs GAG

 13 C 25 % (S.E. 0.63)  34 S 18.5 % (S.E. 0.01)

Benthic Feeders Piscivores

Pinfish Abundance

Trichodesmium Apalachicola River Atmosphere

Nitrogen Sources Apalachicola River 1.7*10 10 g N yr -1 Atmospheric Deposition 5.4*10 10 g N yr -1 Big Bend Pinfish 6.5*10 8 N yr -1 Trophic steps required to become available to gag Tropic transfer efficiency of Nitrogen = 0.28 Apalachicola River 1.3*10 9 –3.8*10 8 g N yr -1 Atmospheric Deposition 1.2* *10 8 g N yr -1 Big Bend Pinfish 6.5*10 8 N yr -1 Based on our estimates a single species of fish (Pinfish) flux ~14-36 % of the total nitrogen available to grouper annually in the N.E. Gulf of Mexico. Since the pinfish flux is directly available as a prey item and is not lost to bacterial respiration or sedimentation we hypothesize that this flux contributes significantly to the high fishery yields in the area.

Nitrogen Sources Apalachicola River 1.7*10 10 g N yr -1 Atmospheric Deposition 5.4*10 10 g N yr -1 Big Bend Pinfish 6.5*10 8 N yr -1 Trophic steps required to become available to gag Tropic transfer efficiency of Nitrogen = 0.28 Apalachicola River 1.3*10 9 –3.8*10 8 g N yr -1 Atmospheric Deposition 1.2* *10 8 g N yr -1 Big Bend Pinfish 6.5*10 8 N yr -1 Based on our estimates a single species of fish (Pinfish) flux ~14-36 % of the total nitrogen available to grouper annually in the N.E. Gulf of Mexico. Since the pinfish flux is directly available as a prey item and is not lost to bacterial respiration or sedimentation we hypothesize that this flux contributes significantly to the high fishery yields in the area.

In our system seagrass habitat and the productive inshore environment provide a significant source of organic matter to the offshore environment via the movement of fishes. This link is critical to the reproduction of a highly valuable fisheries species in the northern Gulf. These fishes also carry organic toxins such as MeHg and thus provide a link between near shore pollution and contamination of food fishes (e.g. grouper and tuna). Globally this phenomenon is likely very common in temperate coast regions where season changes in temperature make near shore waters too cold to inhabit. Stable isotopes provide a powerful tool than can be used to quantify the impacts of ecosystem subsidies.

The TIDE project Trophic cascades and Interacting control processes in a Detritus- based aquatic Ecosystem The TIDE project is a National Science Foundation Integrated Research Challenges in Environmental Biology (IRC-EB) funded study investigating the long-term fate of coastal marshes in the Plum Island watershed. Specifically this project will look at the interactive effects of nutrient enrichment and the removal of top level consumers in several small tidal creeks of the Rowley river.

Consequences in Ecosystems Johnson & Short 2012

Pair-wise Regression R 2 =0.99, p= 0.004

Trophic Bottleneck Observed an increase (4x) in the abundance of inedible long lived snails in fertilized creek. Mummichog experience high mortality over the winter. Increased direct or indirect competition for food between the long lived snail and the short lived mummichog.

Control Conditions

Eutrophic Condition Short Term

Effects on Fisheries Species?

Eutrophic Condition Long Term

Conclusions Eutrophication initially increased production of mummichog but some tipping point was reached and now production is decreasing Possible mechanisms are habitat degradation or a trophic bottleneck. We are working to examine these new questions. Mummichog may provide an important trophic subsidy to striped bass.