Advancing Coastal Habitat Resiliency Through Landscape-Scale Assessment

Figures & data

Table 1. LIS priority habitats included in this assessment.

Habitat	Definition
Eelgrass (Zostera marina)	Rooted underwater marine plant growing along the LIS coast. Primarily found in the Eastern Sound with isolated patches in the Central Sound, although once common throughout LIS.
Estuarine Embayments	Semi-enclosed areas along the LIS's edge that have a defined mouth and freshwater inflow. Names typically include the words cove, river, creek, and harbor. Average depths are shallower than the open LIS and restricted flow causes greater sedimentation.
Tidal Wetlands	Transitional zone between land and submerged systems, these areas are dominated by rooted plants flooded by the tide. Locations are determined by geology and topography.
Riverine Migratory Corridors (RMC)	River systems that drain to the LIS often bordered by trees and wetlands. Migratory fish use rivers to spawn. The majority of rivers flowing into LIS are in Connecticut and Westchester and Bronx Counties, NY.
Coastal Forests	All forested areas within the LIS coastal boundary (Figure 1). Defined in terms of location and vegetation. Dominated by species including maple, oak, cedar, pine, and beech. Occur in small patches throughout the LIS area with a few large swaths remaining (> 100 acres (0.4km^2)).

Figure 1. LIS basins used for habitat status analysis.

Table 2. Eelgrass habitat assessment metrics. Density and Bed Size Metric corresponds to eelgrass surveys in LIS as: VERY LOW = low; LOW = lower half of medium, MEDIUM = upper half of medium, HIGH = high (MacLachlan 2014; Tiner, McGuckin, and MacLachlan 2013).

Metric	Metric Unit & Weight for Scoring	Cut Points	Metric Description
Density and Bed Size^1	Percentage of area within density and bed size categories relative to the total area of eelgrass weight = 33.%	poor: 0 – 35% M or H with < 5% in H; remainder in V or L	Status of a bed is defined by shoot density per m^2 and bed size: Density and bed size categories: (V) VERY LOW: ≤ 24 stems & ≤ 10m^2; (L) LOW: 24-299 stems & 10m^2; (M) MEDIUM: ≥ 300 stems & ≤ 10m^2; (H) HIGH: ≥ 300 stems & ≥ 10m^2.
		fair: 39–59% M or H with < 10% in H; remainder in V or L
		good: 60–75% M or H with ≥ 10% in H; remainder in V or L
		very good: 75–100% M or H with ≥ 10% in H; remainder in V or L
Change in Area in LIS^1	Change in area of eelgrass relative to 2006 (%) weight = 33.%	poor: ≤ –20	Change in area relative to the 2006 baseline of 1,904 acres (7.7km^2). To fall in the very good category overall extent must increase by 5% in each basin. Eelgrass beds naturally fluctuate in size. Ideally, five year averages of annual surveys are evaluated.
		fair: –19 to –6
		good: –5 to 5
		very good: > 5
Epiphytes & Epifauna^2	Degree of colonization of eelgrass blades weight = 33.%	poor: Major, heavy coverage	This indicator is a new addition to eelgrass assessment in LIS. Current epiphyte and epifauna coverage was compared to ideal coverage for LIS.
		fair: Moderate, some coverage
		good: Few, slight coverage
		very good: Very few, little to no coverage

¹ 2006 & 2012 USFWS eelgrass survey data (Tiner, McGuckin, and MacLachlan 2013).

² 2006 & 2012 USFWS eelgrass survey data, MacLachlan field records.

Table 3. Embayment habitat assessment metrics. All data came from a rapid assessment of embayments conducted in late summer, 2011-2013; and are thus directly comparable among all sites (Vaudrey 2015; Vaudrey et al. 2013b).

Metric	Metric Unit &Weight for Scoring	Cut Points	Metric Description
Dissolved Oxygen^1^,^2	Concentration (mg/L) weight = 25%	poor: 0 – 1.99	Average water column value for dawn and midday, collected in late summer. If bottom value is > 4mg/L, samples are from surface (0.5m deep) and bottom (0.5m off bottom). Otherwise, samples collected every 0.5m.
		fair: 2 – 3.49
		good: 3.5 – 4.79
		very good: ≥ 4.8
Chlorophyll a^2	Concentration (µg/L) weight = 25%	poor: 20 – 1000	Midday summer chlorophyll concentration collected from surface (0.5m deep) and bottom (0.5m off bottom). Averaged a minimum of three stations.
		fair: 11 – 19
		good: 5 – 10
		very good: 0 – 5
Macroalgae^3	Summer coverage of hard surfaces by macroalgae indicative of high nutrient loads^4 and reports of bloom frequency (% / bloom frequency) weight = 25%	poor: 71 – 100 / persistent or periodic	Relative coverage of a rack deployed in 3 sites (1 embayment per basin) during late summer, for three weeks.
		fair: 51 – 70 / persistent or periodic
		good: 30 – 50 / episodic
		very good: < 30 / few to none
Eelgrass Loss in Embayments	Area of suitable habitat colonized and interannual stability of colony (%, variability) weight = 25%	poor: 0	Current coverage was compared to predicted coverage. Suitable habitat estimated using a GIS site suitability map based on depth, light, temperature, sediment organic content, and grain size (Tiner, McGuckin, and MacLachlan 2013, Vaudrey et al. 2013a).
		fair: 1 – 49, high
		good: 50 – 79, moderate
		very good: 80 – 100, low

¹ Long Island Sound Study (2017).

² National Coastal Assessment (USEPA 2012).

³ NOAA National Estuarine Eutrophication Assessment (Bricker et al. 2007; Bricker, Ferreira, and Simas 2003).

⁴ Algae indicative of high nutrient inputs include Gracilaria sp., Neosiphonia sp., and green algae.

Table 4. Tidal wetland habitat assessment metrics.

Metric	Metric Unit & Weight for Scoring	Cut Points	Metric Description
Size^1	Average of the Tidal Wetland Units (acres)weight = 25%	poor: < 12	Tidal wetland polygons were extracted from the NWI data and aggregated into Tidal Wetland Units - individual tidal wetland pieces separated by less than 100m (Meiman et al. 2012). From these, an average Tidal Wetland Unit size was derived.
		fair: 13 – 40
		good: 41 – 399
		very good: > 400
Impervious Coverr^2	Tidal Wetland Units in HUC12 basins with > 10% impervious surface cover (%)weight = 25%	poor: ≥ 65	HUC12 basins with > 10% impervious cover were identified and intersected with Tidal Wetland Units; the resulting area of tidal wetlands was expressed as a percentage of total Tidal Wetland Unit area.
		fair: 40 – 64
		good: 16 – 39
		very good: ≤ 15
Open Water^3	Percent open water at low tide (%) weight = 50%	poor: 20 – 40 (> 40 = 0 points)	For Tidal Wetland Units > 10 acres (0.04km^2), 25% were randomly sampled in each LIS basin. Open surface water on these areas was analyzed via photos. Field checks verified surface conditions. Area of open water was calculated as a percent of total area sampled.
		fair: 15 – 20
		good: 10 – 15
		very good: 0 – 10

¹ USFWS National Wetlands Inventory, Tidal Wetlands.

² UConn CLEAR 2010 Impervious Surface Cover for HUC12 Basins; Tidal Wetland Units. HUC12 is the USGS national classification standard for sub watersheds.

³ Tidal Wetlands Units; 2010 Tide Controlled Coastal Infrared Aerial Orthophotography; field surveys.

Table 5. Riverine migratory corridor (RMC) assessment metrics.

Metric	Metric Unit & Weight for Scoring	Cut Points	Metric Description
Connectivity^1	Historic run currently available (%) weight = 60%	poor: ≤ 35	RMC lengths classified as “open” were counted from the downstream terminus to the first impassable obstruction. Total length classified as “open” was divided by the total available RMC length in miles.
		fair: 36 – 55
		good: 56 – 75
		very good: ≥ 75
Impervious Cover^2	RMC within a high impervious cover zone (%)weight = 10%	poor: ≥ 65	RMC lengths within HUC-12 basins with >8% impervious cover were compared to the total RMC length.
		fair: 40 – 64
		good: 16 – 39
		very good: ≤ 15
Water Quality^3	RMC classified as EPA “Not Impaired” (%) weight = 30%	poor: 0 - 40	RMC data corresponding to rivers with EPA Assessed Water Quality data were identified as Assessed RMC miles. These were classified as “Impaired” or “Not Impaired” (i.e., suitable for fish consumption, recreational, or habitat uses). “Not Impaired” RMC miles were expressed as a percentage of the total “Assessed RMC” miles.
		fair: 41 – 70
		good: 71 – 84
		very good: ≥ 85

¹ CT DEEP RMC data layer, updated in 2013 by USFWS, CT DEEP, and TNC.

² UConn CLEAR 2010 Impervious Surface Cover for HUC12 Basins (HUC12 is the USGS classification standard for sub watersheds.); CT DEEP RMC data.

³ USEPA State Water Quality Assessment, Connecticut 305b Assessed Rivers, Lakes, and Estuaries Water Quality for 2012. Drinking water categories excluded.

Table 6. Coastal forest habitat assessment metrics. All metrics used 2010 UConn CLEAR land cover data, 30 m resolution (CLEAR 2012). Fragmentation was determined using the UConn CLEAR Landscape Fragmentation Tool (CLEAR 2007). Only forests within the defined coastal boundary were assessed.

Metric	Metric Unit & Weight for Scoring	Cut-points	Metric description
Size	Average forest block size (acres) weight = 33.%	poor: <50	Deciduous and coniferous forest types were extracted from land cover data, combined, and reprocessed into forest blocks. A forest block includes all forest land cover cells that touch other forest cells on at least one side or corner. Blocks are separated by a minimum of one 30 m by 30 m pixel on all sides and at each vertex. Average block size was then derived.
		fair: 51–150
		good: 151–249
		very good: ≥250
Connectivity	Forest edge that borders developed land (%) weight = 33.%	poor: ≤86–100	Computed forest block perimeters (interior and exterior) connected to developed land cover (developed or turf categories). Values were expressed as a percentage of the total forest block perimeters.
		fair: 51–85
		good: 21–50
		very good: ≤20
Fragmentation	Total forest area in basin designated as core forest area (%) weight = 33.%	poor: <30	UConn CLEAR Landscape Fragmentation Tool (v2) (CLEAR 2007) was run on forest blocks to classify them as patch, buffer, perforated, or core (most to least fragmented). Core forests ≥ 100 acres (0.4 km^2) with a 50 m buffer.
		fair: 31–70
		good: 71–89
		very good: >90

Figure 2. LIS priority habitat health. Habitat scores are out of 100. Colors denote indicator score using evaluation criteria in Tables 2–6. Red is poor, yellow is fair, light green is good, and dark green is very good. Pie chart areas represent weighting applied to indicators when calculating the basin scores.

Figure 3. Comparison of habitat quality with economic valuation. Total value of habitats for the low and high per acre estimate (Table 8) illustrate the relative estimated value of habitats in LIS. Area of each type is presented for comparison. Red indicates poor habitat quality and yellow indicates fair habitat quality as presented in Figure 2.

Table 7. Landscape-level assessments in select coastal programs. white = no habitat extent data found, grey = existing or restored habitat extent tracked; M = multiple indicators tracked; H = multi indicator assessment synthesized into a habitat health rank; N/A = not applicable (ecologically relevant) based LIS habitat definitions.

Table 8. Services, resilience, and value of LIS habitats. Column A includes major contributors to habitat resilience (bold = factors that contribute to habitat resilience in the face of climate change). Column C provides the health status, economic value, current extent, and estimated value to LIS.

	A. Services provided by habitat in LIS area	B. Factors contributing to habitat health and resilience	C. Assessment results for LIS and estimated value.	D. Actions needed to improve or further resilience of the habitat
Eelgrass Beds	feeding grounds, breeding and nursery area, improves water quality by removing nutrients and sediment, flood protection via dampening storm and wave energy, supports recreationally and commercially important finfish and shellfish	High density and area beds provide better habitat. Healthy eelgrass is more resilient to disturbances, recovering more quickly when damaged. Health is improved by good water quality, shading, and cooler temperatures.	Overall, poor. Eastern is good, Central and Western are poor. $9,861 to $28,114 per acre per year ^A 1,640 acres ^B $16.2 - 46.1 million per year	1. Decrease nutrient and sediment inputs from human sources to reduce growth of epiphytes. 2. Encourage development that reduces storm water input. 3. Maintain natural flushing in eelgrass areas to reduce temperatures. 4. Decrease physical disturbance from humans (e.g. dredging, moorings). 5. Plan for migration with sea level rise.
Estuarine Embayments	feeding grounds, breeding and nursery area, can be good areas for submerged aquatic vegetation habitat and tidal wetlands, flood protection via dampening storm energy, commercial and recreational uses	Good water quality and natural levels of tidal and riverine flow support healthy and diverse native communities. Monocultures of nuisance seaweed indicate poor water quality while presence of eelgrass indicates good water quality.	Overall fair. Eastern is good, Central and Western are fair. $2,220 to $4,152 per acre per year ^A 37,313 acres ^C $82.8 - 154.9 million per year	1. Decrease nutrient and sediment inputs from human sources to reduce nuisance seaweed and improve water quality. 2. Protect natural upland areas to intercept nutrients and sediment. 3. Encourage development that reduces storm water input. 4. Maintain natural flushing by reducing tidal and riverine restrictions to keep temperatures low and improve water quality.
Tidal Wetlands	feeding grounds, breeding and nursery area, improves water quality by filtering nutrients and sediment from runoff, flood protection via dampening storm and wave energy, store flood waters as groundwater, supports recreationally and commercially important finfish	Large, contiguous wetlands with good structural integrity provide resilient habitat. A healthy wetland is a mosaic of diverse native plants and animals, with community patterns reflecting tidal influence.	Overall, poor. Eastern is fair, Central and Western are poor. $11,699 to $77,260 per acre per year ^A 14,123 acres $165.2 - $1,091.1 million per year	1. Maintain natural flushing by reducing tidal and riverine restrictions to allow for sediment transport and tidal range (e.g. widen culverts, remove dams). 2. Protect upland buffers to allow for migration inland with sea level rise. 3. Protect upland areas to intercept nutrients. 4. Decrease nutrient inputs from human sources to improve structural integrity of plant communities. 5. Control invasive species (e.g. Phragmites australis).
Riverine Migratory Corridors	spawning and nursery area, moderates streamflow changes, groundwater storage and recharge, sediment transport important for supporting wetland elevation, supports recreationally and commercially important finfish and shellfish, recreational uses	Connectivity is the primary factor; without fish passage, RMC do not function. Good water quality and natural levels of riverine flow are critical. Cooler water temperature is important for many organisms.	Overall fair. Eastern and Western are fair. Central is poor. $248 to $20,537 per acre per year ^D 3,206 acres ^E $0.8 - $65.8 million per year	1. Maintain migration corridors via dam removal or installation of fish ways. 2. Protect and improve vegetated buffers which serve to reduce temperature via shading. 3. Protect natural upland areas to intercept nutrients. 4. When evaluating proposed changes in land-use, consider the impact on water temperature and quality. 5. Maintain natural hydrology by reducing restrictions on river flow or managing flow to allow for sediment transport.
Coastal Forests	complexity of environment supports wildlife diversity, migration corridors, nutrient and carbon storage, improves water quality by filtering nutrients and sediment from groundwater and runoff, wind buffers, recreational uses	Large, contiguous forests with a diversity of native plants and animals provide quality resilient habitat. Connectivity among patches supports wildlife use.	Overall poor. Eastern is fair, Central and Western are poor. $993 to $1,564 per acre per year ^A 130,285 acres $129.4 - $203.8 million per year	1. Protect priority tracts of forest to decrease fragmentation and increase connectivity. 2. Increase connectivity by restoring forests in areas with fragmented patches. 3. Control invasive species to encourage diversity and resilience of native communities.

^A Kocian et al. (2015).

^B Tiner, McGuckin, and MacLachlan (2013).

^C Vaudrey (2015).

^D Kocian et al. (2015) estimate for freshwater does not include valuation of many RMC services and is likely an underestimate of RMC value.

^E Assuming an average river width is 10 m, 806.2 miles of open RMC converts to 3,206 acres.

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