Abt Associates Inc. WA2 - 9_T4_Wetl and.Fish.productivity.memo_12. 24 .09 1 

## Environment and Resources 55 Wheeler Street, Cambridge, MA  Tel: 617 492 - 7100  www.abtassociates.com Date December 24, 2009 To Tom Born , Josh Hall , and Erik Helm U.S. Environmental Protection Agency From D avid Mitchell Subject WA2 - 9 T4_Wetland Fish Production Function memo. The purpose of this memo i s to identify an approximate proportion of total wetland ecosystem function that is associated with fish production for application of willingness - to -pay (WTP ) assessments for the habitats of interest. There is no generally -recognized default proportion of wetland function associated with the fish production function since wetlands vary tremendously. Therefore, a number of qualitative approaches at determining this proportion were investigated and indicated:  Comparison of fish production on a strictly biomass basis (i.e., trophic transfer) provides a minimal estimate (<1% ) of fish production function. This value is considered an underestimate as it does not take into account all of habitat services important for fish production.  HGM wetland functional assessment methods provide examples where fish production function has b een judged by wetland experts to be a major ecosystem function and where it is not. Using recent HGM examples from Gulf Coast states, a gradient of relative importance from 20% to 0% could be possible, depending on wetland type.  Use of a stated preference survey case study in the Northeast provided a public opinion of the relative importance of fish production relative to overall wetland restoration at 25.6%. U sing this information ( discussed below) and best professional judgment , we derive d relative values of the percentage of fish production function for various wetland types and setting s :  For coas tal marine and freshwater tidal marsh areas a value of 2 5 % of wetland function is suggested .  For Great Lakes freshwater coastal marsh areas a value of 20% of wetland function is suggested .  For Inland freshwater wetlands systems, a value of 10% of wetland function is suggested . Further information and detail on these findings and conclusions are contained below. 

## 1 Introduction Wetlands provide a suite of physical, chemical, and biological interactions that are collectively referred to as wetland ecosystem functions. With regard to fish , wetlands can provide an important ecosystem function in their ability to provide critical spawning, nursery, forage and refuge areas for fish species (collectively termed “fish production function”) . The importance of the fish production function of wetlands is highly significant for many species. It has been estimated th at 95% of the finfish and shellfish that are commercially harvested in the United States are wetland - dependent (Feierabend and Zelazny 1987; cited in Street et al. 2005). Yet not all wetlands are equally effective in producing young fish ; some inland wetlands in headwater areas may have negligible fish production. Clearly, the importance of the fish production f

unction will vary significantly between wetland habitat types as well as be highly influenced by the specific properties within the individual wetland. In addition, when wetland restoration has actually been implemented, the actual size, configuration and hydrological regime that are available 

# memorandumAbt Associates Inc. WA2 - 9_T4_Wetl and.Fish.productivity.memo_12. 24 .09 2

may be constrained by site - specific factors and may or may not be conducive to all wetland ecosystem functions (Zedler 2000). Despite this variability, it is useful to identify, if possible, an approximate proportion of total wetland ecosystem function that is associated with fish production for valuation of the wetland restoration/creation needed for restoring lost fish biomass from impingement and entrainment (I & E) losses and appli cation to a public “willingness - to - pay” (WTP) assessment. However, a review of the wetland literature suggests that there are no generally -recognized quantitative or default values as to what percentage of total wetland ecosystem functions are directly associated with fish production. Thi s memo summarizes several lines of evidence that were considered in a first attempt to derive reasonable representative value s , based on:  General Wetland Characteristics  Biomass Transfer Efficiency  Wetland Functional Assessment Methods  Previous WTP work 

### 1.1 G eneral Wetland Characteristics The regional wetland habitat types (and representative species) that we considered for application in the HEA approach for restoring lost fish biomass from I&E losses include marine wetlands (tidal salt marshes ( Spartina alte rniflora ) ; seagrasses (Zostera marina , Thalassia testudinum) ; kelp forests (Macrocystis pyrifera ) and freshwater wetlands (tidal freshwater marshes, non - tidal freshwater marshes ) ( Typha latifolia ). We have discussed these habitat types and their expected l evels of primary productivity previously ( Mitchell et al. 2009 ). There are different sets of e cosystem functions associated with these different types of wetlands. Some of the typical functions that are common to most emergent wetlands ( Spartina, Typha ) include: wave and shoreline protection, surface water storage (including flood control), subsurface water storage and recharge, nutrient and sediment retention , water quality enhancement , maintenance of plant and animal communities, and societal values (e.g. , aesthetics, biodiversity) . For the seagrasses and kelp, the ecosystem functions are less broad but could include wave protection, nutrient retention, w ater quality enhancement, maintenance of plant and animal communities, and societal values. We have muc h less quantitative information on fish production services in seagrasses and kelp forests; so much of the following discussion pertains mainly to emergent wetlands. In addition to the distinction between marine/estuarine habitats and freshwater ones, th e literature also distinguishes between the functional significance of wetlands that are directly connected to or bordering a larger waterbody and those which are isolated or in upper watershed locations (e.g., headwater swamps). The former generally are considered to have higher ecological functions than the latter. For example, the North Carolina Coastal Regional Evaluation of Wetlands Significance (NC - CREWS) evaluated thirty eight wetlands functions for each mapped wetland area within 20 coastal counti es (Street et al. 2005). Wetlands were classified as “exceptional”, “substantial”, or “beneficial” in functional significance. Th e evaluation indicated that riparian wetlands (i.e., those wetlands directly connected to or fringing a larger waterbody) were ranked much higher than non -riparian wetlands ; being greater than 50% in the “exceptional” category and having none ranked lower than “substantial” (Street et al 2 005) . 1.1.1 Marine Habitats Based on the historic literature, there is general consensus that marine tidal wetlands and seagrasses provide good to excellent fish production function for many important commercial, recreational and forage species (Graff and Middleton 2003, Street et al. 2005). Tidal wetlands are well suited for juveniles or young - of- ye ar since they provide: good food availability resulting in high growth rates; increased survivorship due to lowered mortality; and a favorable physico - chemical environment for their development. Marshes are important refuge habitat for young fish due to th e interaction of temperature, turbidity, and dense vegetative structure in reducing the effectiveness of predators (Deegan, Hughes, and Rountree 2000). While the precise role of such habitat s as nurseries for juvenile fish has been recently critically re - examined, suggesting the need for better quantification of the precise role of nearshoreAbt Associates Inc. WA2 - 9_T4_Wetl and.Fish.productivity.memo_12. 24 .09 3

ecosystems in producing more adult fish (Beck et al 2003), the fish production function of tidal wetlands would be considered high. 1.1.2 Freshwater Habitats There is more variability in the importance of fish production within freshwater wetlands. This is due to the greater variety of freshwater wetland environments (freshwater marshes, bottomland flood plain, headwater swamps, bogs, wet meadows, etc.). While some of these fr eshwater wetlands may have important fish production function, there may be little or none associated with others, based on hydrology, geographic locations, water quality or other factors (Graff and Middleton 2003). In particular, tidal freshwater marshes along the seacoast and coastal marshes connected to the Great Lakes have been identified as having important fish production function. Tidal freshwater wetlands are located at the upper end of estuaries and while they experience tidal fluctuations they are essentially fresh in water quality and dominant plant composition (e.g., cattails, bulrushes, etc). These wetlands are commonly used by freshwater, estuarine, marine and migratory fish since their dense vegetation and rapid detritus cycling provides exc ellent refuges for juveniles, spawning areas, and good food availability (Graff and Middleton 2003). Non - tidal freshwater wetlands which are connected to large bodies of water may also have enhanced fish production function. For example, it has been estimated that about 75% of the fish species in the Great Lakes utilize coastal marshes during some part of their life cycle (Stephenson 1990 , Jude and Pappas 1992, Meixler 2005). Lake Erie is reported to s upport the best fishery of the Great Lakes, in terms of diversity and number, partly because of its extensive system of adjoining coastal marshes (Graff and Middleton 2003) . The importance of fish production in isolated non - tidal freshwater wetlands, forested wetlands (i.e., seasonally flooded areas) , swam ps, bogs, etc. has not been well - quantified but has the potential to be far less than that found in either tidal or coastal situations. Small wetlands attached to lakes or fringing marshes on ri vers may be locally productive. However, i nland wetlands , such as isolated shallow depressions, headwater swamps, or seepage - derived wetlands may have poor or non - existent fish production (Graff and Middleton 2003). Thus the anticipated potential for fish production in non - coastal i nland wetlands would be lower. 

### 1.2 Bio mass t ransfer efficiency Consideration of the transfer efficiency of biomass production via trophic feeding links is one quantitative way of estimating the importance of the wetland habitat to fish production. For application of the HEA trophic transfer approach to estimate necessary habitat size to restore I & E losses, we have assumed that the rate of biomass transfer from primary producers to secondary consumers (i.e., juvenile fish and invertebrate production) is fixed at a certain percentage of the pri mary production . These transfer rates were obtained from Natural Resource Damage Assessment (NRDA) cases and other restoration projects (see Stapler et al 2008) . For example, the coastal wetland restoration project conducted by PSEG in New Jersey used a net transfer rate of 0.0088 from primary production to fish and invertebrates (this value include d an adjustment for carbon export of 45% out of marsh). For the Lake Barre oil spill restoration, Penn and Tomasi ( 2002 ) used a slightly lower net biomass transfer from marsh primary producers to fish and invertebrates of 0.008 . The small magnitude of the biomass transfer rates should not be used as indicative of the proportion of total wetland function that is a ssociated with fish production. This is because this biomass transfer only considers the trophic feeding aspect of fish production, while it has been shown that favorable growth conditions and protection from predators may be an equally important function of the wetland habitat (Deegan et al., 2000) . Thus , it is not only the production of detritus going into the food chain that isAbt Associates Inc. WA2 - 9_T4_Wetl and.Fish.productivity.memo_12. 24 .09 4

critical, but the physical structure, reduced energy environment, and diversity of sub -habitats that are necessary to have successful fish production. 

### 1.3 Wetland functional as sessment methods Wetland functional assessment s were developed as tools to quantify the level of applicable f unction s of a particular wetland. One of the more commonly used methods is the hydrogeomorphic (HGM) functional assessment (Smith et al.1995). The HGM fundamentals have been incorporated into most current wetland functional assessment s and , as of 2008 , the U.S. Army Corps of Engineers (USACE) had developed and approved 18 regional guidebooks compiled by wetland experts for application at the local le vel (NRCS 2008) . Rec ent regional HGM documents were reviewed to see how fish production functions are translated into this method (if at all) and what was the relative importance of the fish production function compared to other wetland functions . We examined three recent regional guidebooks pertaining to wetlands in the same geographic region ( Alabama and Mississippi , West Gulf Coastal Plain ) and which dealt with coastal tidal fringe wetlands (Shafer et al. 2007) , forested wetlands (Klimas et al. 2005), and inland headwater slope wetlands (Noble et al 2007). For the coastal tidal wetlands, the five major wetland functions were: (1) wave energy alteration; (2) biochemical cycling; (3) nekton utilization potential; (4) provide habitat for marsh - dependent wi ldlife; and (5) characteristic plant community structure and composition (Shafer et al 2007). Fish production was represented by nekton utilization potential, which was a composite functional capacity index (FCI) derived as an average of three wetland attributes

– aquatic edge, hydrology and nekton habitat diversity (NHD) . These wetland attributes are of interest, because they indicate the wetland features that are more critical to fish and shellfish production. Aquatic edge i s a composite measure of the amount of tidal drainage network, the percentage of the wetland perimeter exposed to tide, and percentage of shoreline relative to total wetland area. The hydrology index i s based on the amount of site open to free exchange of tidal energy, the amount of inundation of the lower marsh area, and amount of hydrologic alteration. The NHD rate s the presence of a number of sub -habitats that typically support fish and invertebrate production including: low marsh, high marsh, intertidal creeks/channels, sub - tidal creeks/channels, ponds or depression (temporary or permanent), shallow (<1 m) sand or mudflats, submerged aquatic vegetation (SAV) and oyster reef. For the highest possible NHD rating, a wetland needs to have 5 of these sub -habitats present (Shafer 2007) . For the inland forested wetlands, a different set of six major wetland functions were used: (1) detain floodwater ; (2) detain precipitation ; (3) c ycle nutrients ; (4) export organic c arbon ; (5) maintain plant c ommunities ; and (6 ) provide habitat for fish and wildlife ( Klimas et al 2005 ). Emphasis on habitat value includes both fish and higher animals. In contrast, the regional guidebook for evaluating functions in slope headwater swamps (i.e., groundwater seepage derived wetlands) does not include a provision for fish production, indicating that this is not an important wetland function in that types of system (Noble et al 2007). Review of this guidebook indicates that these wetland habitats are considered more critical as habitats for amphibians or birds than for fish. The HGM does not result in an overall s ummary score or index but is used, in conjunction with the areal weighting of the various wetland areas, to compare overall functional units to reference wetlands or to gauge the level of impact of a propo sed project. Nonetheless, all major wetland functions are equally scored and considered under HGM , so for coastal wetlands, a relative proportion of 2 0% of overall wetland function theoretically w ould be attributed to fish production while a similar consi deration for the forested wetland would be 16% with a negligible value (0%) for the headwater swamp. Given the nature of the HGM protocol , these values should not be used directly, but in the selection of important wetland functions for particular wetlan ds, the guidebooks document some degree of de facto best professional ju dgment (BPJ) of wetland experts that clearly distinguish a gradient of relative importance of fish production from coastal to inland upland settings.Abt Associates Inc. WA2 - 9_T4_Wetl and.Fish.productivity.memo_12. 24 .09 5

Another common wetland assessment method, based on an index of biological integrity (IBI) , was examined for identification of fish production importance . An IBI - based method evaluates a wetland’s ability to maintain a balanced community, having a species composition, diversity and functi onal organization comparable with that of minimally disturbed (i.e., reference) wetlands within a region (USEPA 1998). However, the IBI uses the condition of selected biota (e.g., vascular plants, periphyton, macroinvertebrates, fish, amphibians, birds) to arrive at a summary score (index) to evaluate whether the wetland is potentially being degraded by chemical, physical or biological stressors. While IBI methods supports this type of decision - making they do not provide direct information regarding the status and importance of individual functions. 

### 1.4 Previous WTP work Another independent approach to the relative valuation of ecosystem services is based on the public WTP to restore a wetland habitat and its perceptions about the importance of various functio ns of that habitat . Accordingly, i t wa s possible to identify, based on a stated preference survey , public opinion regarding the approximate proportion of total wetland ecosystem value that is associated with fish production functions . The Narragansett Bay Wetland Restoration Study allowed an opportunity for public input on a survey to judge the importance of the proportion of a restored wetland’s value attribut able to fish habitat services (Johnson et al 2002) . Under various restoration scenarios, this valu e ranged from 20.4 to 32.3%, with an overall mean of 25.6% (USEPA, 2004). 

## 2 General Findings The purpose of this memo was to identify an approximate proportion of total wetland ecosystem function that is associated with fish production; for application of WTP a ssessments for the habitats of interest . A number of qualitative approaches at determining this proportion were investigated and indicated :  H abitat fish production function refers to the collective ecosystem characteristics which provide critical spawning , nursery, forage and refuge areas for juvenile or young - of- year fish species.  There is no generally -recognized default proportion of wetland function associated with the fish production function since wetlands vary tremendously. Less in known regarding the fish production function in seagrasses and kelp forests than emergent wetlands .  There is general recognition in the literature that the following wetland habitats have potentially high fish production significance : coastal tidal wetlands, freshwater tid al wetlands, and Great Lakes coastal wetlands.  Non - coastal inland wetlands are more likely to have a low er fish production function.  Comparison of fish production on a strictly biomass basis (i.e., trophic transfer) provides a minimal estimate (<1%) of fi sh production function. This value is considered an underestimate as it does not take into account all of habitat services important for fish production.  HGM wetland functional assessment methods provide examples where fish production function has been judged by wetland experts to be a major ecosystem fu nction and where it is not. Using recent HGM examples from Gulf Coast states, a gradient of relative importance from 20% to 0% could be possible , depending on wetland type .  Use of a stated preference survey case study in the Northeast provided a public opinion of the relative importance of fish production relative to overall wetland restoration at 25.6%. 

## 3 Conclusions As discussed above, there are no generally -recognized quantitative or default values as to w hat percentage of the total wetland ecosystem functions are directly associated with fish production for the habitats of interest . We also recognize the great variability possible within the same habitat type based on the presence or absence of features co nducive to fish production. Nonetheless, using the informationAbt Associates Inc. WA2 - 9_T4_Wetl and.Fish.productivity.memo_12. 24 .09 6

discussed above and BPJ, there is sufficient qualitative consensus to suggest the following relative values of the percentage of fish production function to aid in the WTP estimates:  For coas tal marine and freshwater tidal marsh areas a value of 2 5 % of wetland function is suggested; based on the generally -recognized qualitative importance of this habitat to coastal fisheries. This value is comparable to the stated preference value of 25.6%.  For Great Lakes freshwater coastal marsh areas a value of 20% of wetland function is suggested , based on the generally -recognized i mportance of this habitat to Great Lakes fisheries. The slightly lower value compared to marine systems reflects the absence o f the regular tidal cycle which provides more sub -habitat diversity within the system.  For Inland freshwater wetlands systems, a value of 10% of wetland function is suggested. This intermediate value reflects the diversity of wetland types as well as the lower fish production potential of some isolated inland wetlands included in this category. These values should be considered a first approximation that could be refined through additional data collection and investigation of site - specific factors.Abt Associates Inc. WA2 - 9_T4_Wetl and.Fish.productivity.memo_12. 24 .09 7

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– Regional Benefits Assessment, Part A: Evaluation Methods, Chapter A - 15. Zedler, J. 2000. Progress in wetland restoration ecology. Tree 15:402 - 4 07.