Endangered and Threatened Species; Threatened Status for Johnson's Seagrass

Federal RegisterSep 14, 1998

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 227

[Docket No. 980811214-8214-01; I.D. 052493B]

Endangered and Threatened Species; Threatened Status for

Johnson's Seagrass

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and

Atmospheric Administration (NOAA), Commerce.

ACTION: Final rule.

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SUMMARY: NMFS is issuing a final rule determining Johnson's seagrass

(Halophila johnsonii) to be a threatened species pursuant to the

Endangered Species Act (ESA) of 1973, as amended, which means it is

likely to become an endangered species within the foreseeable future

throughout all or a significant portion of its range. Johnson's

seagrass is rare and exhibits one of the most limited geographic

distributions of any seagrass. Within its limited range (lagoons on the

east coast of Florida from Sebastian Inlet to central Biscayne Bay), it

is one of the least abundant species. Because of its limited

reproductive capacity (apparently only asexual) and limited energy

storage capacity (small root-rhizome structure and high biomass

turnover), it is less likely to be able to repopulate an area when lost

due to anthropogenic or natural disturbances. NMFS will soon issue

protective regulations under section 4(d) of the ESA for this species.

DATES: Effective October 14, 1998.

ADDRESSES: Colleen Coogan, NMFS, Southeast Region, Protected Resources

Division, 9721 Executive Center Drive, St. Petersburg, FL 33702-2432;

Angela Somma, NMFS, Office of Protected Resources, 1315 East-West

Highway, Silver Spring, MD 20910.

FOR FURTHER INFORMATION CONTACT: Colleen Coogan, Southeast Region,

NMFS, (727) 570-5312, or Angela Somma, Office of Protected Resources,

NMFS, (301) 713-1401.

SUPPLEMENTARY INFORMATION:

Background

NMFS published a proposed rule to list Johnson's seagrass as a

threatened species on September 15, 1993 (58 FR 48326). Designation of

critical habitat was proposed on August 4, 1994 (59 FR 39716). A public

hearing on both the proposed listing and critical habitat designation

was held in Vero Beach, Florida, on September 20, 1994. NMFS reopened

the comment period for the proposed listing on April 20, 1998 (63 FR

19468).

The information forming the basis for NMFS' 1993 proposal has been

peer reviewed, and new information confirms NMFS' conclusions regarding

the threatened status of Johnson's seagrass. As stated in the notice

reopening the comment period, the additional information supplements

available data on the status and distribution of Johnson's seagrass. In

order to update the original status report (Kenworthy, 1993) and to

include information from new field and laboratory research on species

distribution, ecology, genetics and phylogeny, NMFS convened a workshop

on the biology, distribution, and abundance of H. johnsonii. The

results of this workshop, held in St. Petersburg, Florida, in November

1996, were summarized in the workshop proceedings (Kenworthy, 1997)

submitted to NMFS on October 15, 1997. The notice reopening the comment

period contains a summary of the workshop proceedings (63 FR 19468).

This final rule contains a brief description of those workshop

proceedings, and updates the research findings and analysis since NMFS'

1993 proposal.

Updated Status Report

The biology of Johnson's seagrass is discussed in the proposed rule

to list the species as threatened (58 FR 48326, September 15, 1993).

The proposed rule includes information on the status of the species,

its life history characteristics, and habitat requirements. Johnson's

seagrass is one of twelve species of the genus Halophila. Halophila

species are distinguished morphologically from other seagrasses in

their possession of either a pair of stalked leaves without scales or a

pseudo whorl of leaves. Identifying characteristics of H. johnsonii

include smooth foliage leaves in pairs 10-20 mm long, a creeping

rhizome stem, sessile (attached to their bases) flowers, and longnecked

fruits. Most Halophila species are reduced in size, more shallow

rooted, and have two to three orders of magnitude less biomass per unit

area compared to all other seagrasses. The most outstanding difference

between H. johnsonii and other species is its distinct differences in

sexual reproductive characteristics. While H. decipiens is monoecious

(has both female and male flowers on the same plant) and successfully

reproduces and propagates by seed, H. johnsonii is dioecious (has

flowers of a single sex on the same plant). However, the male flower

has never been described either in the field or in laboratory culture.

The absence of male flowers supports the hypothesis that sexual

reproduction is absent in this species, and propagation must be

exclusively vegetative. After periods of unfavorable environmental

conditions of growth and vegetative branching, the regrowth and

reestablishment of surviving populations of Johnson's seagrass would be

significantly more difficult than for species with a sexual life

history.

[[Page 49036]]

The status review that led to the proposed rule to list this

species as threatened under the ESA included data from extensive field

work at three sites (Hobe and Jupiter sounds, Sebastian Inlet, and Ft.

Pierce Inlet) in the Indian River area during 1990 to 1992. Johnson's

seagrass was the least abundant of the seagrass species within the

study area and was distributed in patches that range in size from a few

centimeters to hundreds of meters. Biomass, patch sizes, and leaf pair

densities were always less than those measured in H. decipiens. The

destruction of the benthic community due to boating activities,

propeller dredging and anchor mooring was observed at all sites during

this study.

Based on new qualitative and quantitative benthic surveys and

interviews with scientists, the workshop report confirmed the extremely

limited geographic distribution of H. johnsonii to patchy and

vertically disjunct populations between Sebastian Inlet and northern

Biscayne Bay on the east coast of Florida, finding no verifiable

sightings outside the range already reported. Since additional surveys

did not locate any male flowers, nor was seedling recruitment

confirmed, the restricted distribution and abundance of Johnson's

seagrass is attributed to a reliance on vegetative means of

reproduction and growth (Kenworthy, 1993; Kenworthy, 1997). High

densities of apical meristems, rapid rates of horizontal growth, and a

fast biomass turnover were suggested to explain the appearance and

disappearance of H. johnsonii observed in disturbed areas and on fixed

survey transects. The workshop report confirms the conclusions from the

previous data.

The results of expanded surveys during the period 1994 to 1996

corroborated previous information that: (1) H. johnsonii does not occur

further north than Sebastian Inlet; and (2) areal distribution is

patchy and disjunct from Sebastian Inlet to Jupiter Inlet.

Additionally, these transects confirmed that H. johnsonii occurs over a

depth range extending from the intertidal down to approximately -2 m

mean tidal height. Average percent cover of H. johnsonii per transect

ranged from a minimum of 0.2 percent in winter 1996 to 8.5 percent in

summer 1994. Relative to the other six species that occur in the

lagoon, H. johnsonii comprises less than 1.0 percent of the total

abundance of seagrasses. The transect data corroborates previous

intensive surveys in Jupiter and Hobe sounds, and near Fort Pierce

Inlet (Kenworthy, 1993; Gallegos and Kenworthy, 1995; Kenworthy, 1997).

The potential for vegetative expansion, a perennial and intertidal

growth habit, and a relatively high tolerance for fluctuating salinity

and temperature may enable Johnson's seagrass to colonize and thrive in

environments where other seagrasses cannot survive (Kenworthy, 1993;

Kenworthy, 1997). Additional molecular genetic information was reviewed

in the workshop which supports distinguishing H. johnsonii as a

separate species from H. decipiens (Kenworthy, 1993), although more

detailed and extensive phylogenetic studies were suggested to determine

the origin and source of genetic diversity in Johnson's seagrass

(Kenworthy, 1997). The first quantitative evidence of faunal community

diversity and abundance in H. johnsonii meadows was also reported at

this workshop. Results indicated that the infaunal communities of H.

johnsonii are more similar to the larger seagrass, Halodule wrightii

than to unvegetated bottom.

It is the policy of NMFS and the U.S. Fish and Wildlife Service

(FWS) to solicit the expert opinions of three appropriate and

independent specialists regarding pertinent scientific or commercial

data and assumptions relating to the taxonomy, population models, and

supportive biological and ecological information for species under

consideration for listing. Also, it is NMFS' policy to summarize in the

final decision document the opinions of all independent peer reviews

received and to include all such reports, opinions, and other data in

the administrative record of the final decision.

In response to NMFS's three solicitations of peer review on

Johnson's seagrass, a response was received from Susan Williams, Ph.D.,

Associate Professor, Department of Biology and Director, Coastal and

Marine Institute, College of Sciences, San Diego State University and

from Kimon T. Bird, Ph.D., Center for Marine Science Research,

University of North Carolina at Wilmington. Their opinions, which

support the NMFS listing proposal, are included in the following

Summary of Comments section.

Summary of Comments

The State of Florida's Department of Environmental Protection

(FDEP) and Department of Community Affairs (DCA) submitted several sets

of comments. Many of these comments pertained to the consideration of

critical habitat designation, which is not being determined in this

rulemaking. For this present rule, NMFS will address only the comments

related to the listing of Johnson's seagrass as threatened.

The December 8, 1993, comments from FDEP concurred that threatened

status under the ESA should be assigned to Johnson's seagrass because

its distribution is among the most restricted of seagrass species,

because it lacks sexual reproduction, and because it depends on

vegetative reproduction. All of these factors make it particularly

vulnerable to local extinction from various perturbations or

environmental changes.

FDEP stated that johnsonii and other Halophila species have been

shown to have relatively high productivity and turnover rates and may

be more ecologically important than previously thought. Designation as

a threatened species would encourage further study of Johnson's

seagrass and would assist FDEP in developing conservation plans. Also,

FDEP agreed with NMFS that existing protection for this species was

inadequate.

FDEP included the following caveats: First, the presently known

geographical locations include several inlets that have regularly

experienced maintenance dredging (one since 1948). Yet Johnson's

seagrass is still evident around these inlets and in other areas of

high human use. It could be argued that maintenance dredging has

enhanced this species, or at least not harmed it. Second, the proposed

rulemaking states that there is no evidence that commercial,

recreational, scientific or educational activities have contributed to

the decline of this species. If this species is listed, what more needs

to be done to protect it? Third, identification of this species is

difficult except by seagrass experts. Those individuals surveying sites

need to understand how to clearly identify H. johnsonii in the field.

In March 1994, NMFS received additional comments from FDEP

concerning the listing proposal, stating that Johnson's seagrass has

only recently been recognized as a separate species and that FDEP is

seriously concerned with the general lack of knowledge about the

organism, especially the many aspects of basic life history. FDEP

assumed that the listing of this species as threatened under the ESA

should promote the collection of additional knowledge for improved

management decisions, including the ability to properly identify the

plant in the field. Other Halophila species have been underestimated

regarding their importance to nearshore ecosystems, and the FDEP did

not want this species to be overlooked if it had a significant role.

FDEP recommended that NMFS consider conducting an appropriate research

program linked to the listing process and that more must be known

[[Page 49037]]

about the species so that the most appropriate management strategies

can be developed. FDEP restated the caveats made in the December 1993,

response.

In September 1994, FDEP commented that the steps being taken by

NMFS are necessary to adequately protect this species from loss

associated with human-related activities. Although FDEP had

reservations as to the effects of inlet-related maintenance activities

on the continued existence of Johnson's seagrass, it noted that it is

clear that direct removal of existing seagrass will be detrimental to

the survival of this species. It supported listing the species as a

threatened species.

In January 1994 and June 1994, DCA responded to NMFS' request for a

coastal zone consistency determination for the designation of critical

habitat for Johnson's seagrass. Although DCA referred to both the

proposed listing and critical habitat designation in responses to NMFS,

the comments from individual state agencies and departments addressed

primarily the critical habitat portion.

In 1998, DCA wrote, on behalf of the state, that it does not object

to the listing of Johnson's seagrass as a threatened species.

Other Comments

Issue 1: Several commenters questioned whether NMFS has adequate

information to determine that Johnson's seagrass should be listed.

Others questioned whether it is a separate species rather than a

possible mutation or an exotic species not native to the area. Some

questioned whether NMFS could list a species without knowing how it

reproduces.

One of the peer reviewers, Dr. Susan L. Williams, stated that while

there are data gaps for the species and such data should be obtained,

it is justifiable to extrapolate from other species in the genus

because seagrass congeners are remarkably alike in their ecology. While

it is important to clarify the taxonomic status of the species, it is

not an issue that needs to be resolved before listing because the

morphology of H. johnsonii is distinct enough from H. decipiens to

enable field identification and thus its distribution across habitats.

In response to questions on whether H. johnsonii is a separate

species, another peer reviewer, Dr. Kimon T. Bird, stated that the

morphological and flowering characteristics of this species are

markedly different from the conspecific species H. engelmanii and H.

decipiens. Recently, H. johnsonii was compared to other Halophila

species from Florida and the Indo-Pacific using isozymes sulfated

flavonoids and DNA fingerprinting (Jewett-Smith et al. 1997). Based on

these analyses, H. johnsonii separates out well from other Halophila

species in Florida and appears more similar to the narrow leaved forms

of the Indo-Pacific based on the use of this DNA analysis.

Regarding the mode of reproduction, Dr. Bird stated that the data

provided support the absence of seeds, and he agrees that this species

reproduces only by asexual methods. Dr. Williams states that there is

concern about the lack of evidence of sexual reproduction since male

flowers have not been observed in H. johnsonii. Furthermore, the sexual

reproduction by seagrasses is poorly understood compared to other

angiosperms (e.g. seaweeds), and there have been cases where further

studies have revised conclusions on asexuality. Apomixis (vegetative

reproduction where normal sexual processes are not functioning or

greatly reduced in number) has not been verified in seagrasses.

Nonetheless, considerable field surveys and collections have been

conducted on H. johnsonii to conclude that if males and/or viable seeds

do occur, they are quite rare in the areas studied. Thus, the

attributes of potentially limited distribution, rare (if present at

all) sexual reproduction, and uncertain vegetative dispersal makes the

species prone to disturbance. Dr. Williams also concludes that limited

and isolated populations of H. johnsonii that rely primarily on

vegetative dispersal are probably very prone to local extinction due to

disturbances and stochastic events. The numerous field searches and

laboratory transplant culture experiments have indicated the presence

of pistillate flowers (no staminate flowers (i.e., only asexual

reproduction) over the 16 years since H. johnsonii was first described.

NMFS Response: The 1996 NMFS sponsored workshop addressed several

of these concerns. For example, since additional surveys have not

located any male flowers, nor has seedling recruitment been confirmed,

the workshop report attributed the distribution and abundance of

Johnson's seagrass to a reliance on vegetative means of reproduction

and growth. High densities of apical meristems, rapid rates of

horizontal growth, and a fast leaf turnover were suggested to explain

the appearance and disappearance of H. johnsonii observed in disturbed

areas and on survey transects. The workshop report suggests that this

potential for vegetative expansion, a perennial and intertidal growth

habit, and a relatively high tolerance for fluctuating salinity and

temperature may enable Johnson's seagrass to colonize and thrive in

environments where other seagrasses cannot survive.

Additional molecular genetic information was reviewed in the

workshop which supports distinguishing H. johnsonii as a separate

species from H. decipiens, although more detailed and extensive

phylogenetic studies were suggested to determine the origin and source

of genetic diversity in Johnson's seagrass.

Issue 2: Some commenters believe the species is much more abundant

in South Florida than the status review indicates and that it occurs in

places other than the east coast of Florida (e.g., Bahamas or Florida

west coast).

Dr. Bird states that he contacted three trained marine botanists

along the west coast of Florida. They reported that they had never seen

H. johnsonii along the west coast. In addition, McMillan made no

reference to its presence in Texas when writing the paper describing

the new species, even though he is far more familiar with the marine

botany of Texas than Florida. While several commenters reported seeing

it in the Bahamas, their observations were anecdotal. Based on the

information provided, Dr. Bird concurs that H. johnsonii is limited to

a narrow geographic range along the east coast of Florida.

Dr. Williams states that knowledge of the distribution of H.

johnsonii throughout the subtropical and tropical Atlantic should be

extended, but it should not affect listing the species because in its

known distribution, it is vulnerable to disturbances of dredging and

reduced water clarity, as are all the co-occurring seagrass species.

NMFS Response: In 1986, Robert Virnstein (St. John's River Water

Management District) and Kalani Cairns (U.S. Fish and Wildlife Service)

mapped a 50-mile section of the Indian River Lagoon from St. Lucie

Inlet to Sebastian Inlet. Even though H. johnsonii and H. decipiens

seemed to be proliferating, data did not indicate whether this was a

trend or a one-time increase. Also, because both species have short

leaves, they may have been overlooked in previous surveys. They stated

that 1986 was considered a ``good'' year for seagrasses even though

many areas were ``stressed'' and had lost seagrasses. Furthermore, they

opined that one ``bad'' year could result in the loss of up to half of

the present coverage and no one could predict whether such loss would

be permanent or that the species would recover.

Virnstein and Morris (1996-personal communication) have said that

their 3-year study of 74 seagrass transects in the

[[Page 49038]]

Indian River Lagoon has yielded information on deeper water

distributions measuring a few centimeters to more than several hundred

meters. These results do not change the distributional limits within

the original range of the species.

The report of the NMFS workshop confirms the extremely limited

geographic distribution of H. johnsonii to patchy and vertically

disjunct areas between Sebastian Inlet and northern Biscayne Bay on the

east coast of Florida, finding no verifiable sightings outside of the

range already reported. This finding is based on new qualitative and

quantitative benthic surveys and interviews with scientists.

Issue 3: Some commenters remarked that it is difficult to identify

Johnson's seagrass in the field and that those reviewing sites need to

understand how to clearly identify the species.

NMFS Response: Distinct morphological differences allow for both

field and laboratory differentiation of the species. H. johnsonii is

distinct from the conspecific H. decipiens in basic leaf

characteristics. H. johnsonii has elongated linear leaves with complete

margins and H. decipiens has broad, elliptical (paddle-shaped) leaves

with serrated margins. Increased outreach after listing, including

recovery planning and section 7 consultations, will improve

stakeholders' familiarity with these differences.

Issue 4: Some commenters questioned the presence of Johnson's

seagrass near inlets that have been routinely dredged for years and in

other areas of high human usage. The question is whether certain

dredging, especially maintenance dredging, impacts Johnson's seagrass,

or whether the species occurs in these areas as a result of dredging.

NMFS Response: The effects of maintenance dredging on Johnson's

seagrass have not yet been characterized. Johnson's seagrass requires

suitable salinity levels, water transparency, and water quality as well

as stable, unconsolidated sediments. These elements are found in

shallow waters and shoals around inlets and disturbed areas as well as

in undisturbed, more isolated deeper areas of the lagoon. Common

factors in its distribution appear to be its ability to grow in

association with other species and its ability to survive in shallow

intertidal flats environments typical of the flood tide deltas near

inlets. Johnson's seagrass may extend the coverage of seagrasses within

lagoons in some of the zones where other grasses do not grow.

Dr. Bird questions the ability of H. johnsonii to withstand nearby

dredging activities because the sediments of the Indian River contain a

good deal of highly organic particulate materials. When resuspended by

dredging activities or other physical disturbances, the fine

particulate material can attenuate light (reducing Photosynthetically

Active Radiation (PAR)) and be a limiting factor in photosynthesis and

subsequent seagrass growth and maintenance.

Several scientists working in the area and for the state of Florida

stated that it is clear that direct removal of existing seagrass

through new construction will be detrimental to the survival of

Johnson's seagrass. There have been no reports of healthy populations

outside the presently known range. The survival of the species likely

depends on maintaining existing viable populations, especially in areas

where large patches are found.

Issue 5: Some commenters said that seagrasses have overwhelming

importance to the ecology and economy of South Florida. Seagrasses are

high primary producers within their ecosystem. They provide valuable

habitat as nurseries, provide refuge for fisheries, and recycle

nutrients throughout their ecosystems. Seagrasses are also a food

source for endangered green turtles and the Florida manatee. When

seagrass beds disappear, fishery productivity also decreases. They

noted that declines in seagrass beds have been documented worldwide,

particularly in the Indian River Lagoon, the primary habitat of H.

johnsonii.

NMFS Response: NMFS agrees that seagrasses play an important role

in their ecosystems and provide valuable habitat. The vulnerability of

seagrasses in general and H. johnsonii in particular, provides the

impetus for this listing.

Issue 6: Some commenters said that the species should be listed as

endangered rather than threatened, and that NMFS underestimated the

effects of climate change and increasing development and population

growth in Florida.

NMFS Response: NMFS believes that only limited information exists

regarding Johnson's seagrass, reproductive capacity, life history

characteristics (growth rates, environmental requirements), and the

effects of human disturbance which would be necessary in determining

that Johnson's seagrass is in danger of extinction throughout all or a

significant portion of its range. The protection afforded by listing as

threatened will result in the subsequent development of a recovery plan

for H. johnsonii. The recovery plan will address the gaps in our

knowledge of the biology and ecology of Johnson's seagrass, and such

knowledge will, in turn, lead to a better understanding of the

demography and population biology of this species.

Dr. Bird states that although the evidence points to a valid

species with a limited distribution, the questions of its degree of

extinction is more difficult to resolve. Halophila species as a whole

appear to be patchy with few species developing extensive stands.

However, he agrees with NMFS' conclusions that human activities in the

area could impact the species. Existing criteria and standards, as well

as enforcement measures, are inadequate to protect seagrasses.

Issue 7: Several commenters expressed concern about whether

maintenance dredging of existing inlets and channels would be allowed

to continue if Johnson's seagrass is listed.

NMFS Response: NMFS is concerned about the possibility of losing

patches of Johnson's seagrass that may be essential to the genetic

viability of the species. However, NMFS expects that maintenance

dredging activities will be authorized with the oversight provided by

section 7 of the ESA.

Issue 8: Several commenters were concerned that the listing of

Johnson's seagrass would prevent or severely curtail expansion or

development of ports and maintenance of existing ports, channels and

inlets. In turn, this would adversely affect the economy in their

communities.

NMFS Response: The ESA mandates that listing determinations be made

solely on the basis of the best scientific and commercial data

available after conducting a review of the status of the species and

taking into account those conservation efforts being made by any state.

However, section 7 of the ESA provides a mechanism for actions

requiring Federal funding permits or participation to be conducted in a

manner that prevents jeopardy to any species. Therefore, NMFS

anticipates that most marine related activities can continue when

measures are taken through the section 7 consultation process with

Federal agencies to reduce adverse impacts and avoid jeopardizing the

continued existence of the species.

Issue 9: Some commenters stated that any threats to the habitat

could be corrected or were being corrected without the species being

listed. For example, problems due to prop scarring could be resolved by

marking navigation channels and establishing speed zones. Several

counties are installing storm water management systems to improve

[[Page 49039]]

water quality. Maintenance dredging is regulated by the state, and

spoil is now deposited on beaches to protect shorelines rather than on

spoil islands.

NMFS Response: Other embayments in the distributional range of

Johnson's seagrass have marked navigational channels, but seagrass bed

scarring still occurs. ``Many of the sea-grass beds in the Indian River

Lagoon have prop scars resulting from boaters attempting to cross

shallow waters and running aground'' (Indian River Lagoon Comprehensive

Conservation and Management Plan, May 1996). Erosion caused by damage

from boat wakes may also result in turbidity and siltation, which

adversely affect seagrass.

Issue 10: One commenter wrote that the updated information

provided by NMFS reveals that the species is doing well, and shows no

signs of decrease in health or population. The commenter also wrote

that its geographic range was, if anything, larger than what was

reported in 1993.

NMFS Response: In order to update the original status report

(Kenworthy, 1993) and to include information from new field and

laboratory research on species distribution, ecology, use, genetics and

phylogeny, NMFS convened a workshop on the biology, distribution, and

abundance of H. johnsonii. The results of this workshop, held in St.

Petersburg, Florida, in November 1996, have been summarized in the

workshop proceedings (Kenworthy, 1997) submitted to NMFS on October 15,

1997. The new information confirmed NMFS' original determination that

the species should be listed as threatened. This final rule is based on

updated information.

Issue 11: Some commenters noted that in the proposed rule, NMFS

stated that there is no evidence that the overutilization for

commercial, recreational, scientific or educational purpose contributed

to the decline of Johnson's seagrass. If this listing factor has not

contributed to the decline, they questioned what more needs to be done

to protect the species.

NMFS Response: This factor refers to the actual use of the species

itself. For example, if a plant were harvested commercially for food,

medicines, or other products, this use might have contributed to the

decline of the organism. Johnson's seagrass habitat may be affected by

other resource harvesting activities in the ecosystem, but the species

itself is not used for commercial, recreational, or educational

activities.

Issue 12: Several commenters stated that there are adequate Federal

and State laws to protect all seagrasses which make the additional

protection afforded by the ESA unnecessary.

NMFS Response: While it is clear that the intent of Federal and

Florida state laws is to conserve and protect seagrass habitat, it is

also clear that there is continued and well-documented loss of seagrass

habitat in the United States and elsewhere. For example, seagrasses

have declined in many areas of the Indian River Lagoon (Virnstein and

Morris, 1996).

Previous transplantation efforts to mitigate for the loss of

seagrass beds have failed. Until recently, Halophila species have not

been transplanted successfully in the field and studies underway are

incomplete (Kenworthy-personal communication). Many seagrass ecosystems

are known to recover very slowly even under the most natural, pristine

conditions. Current efforts are insufficient to protect critical

seagrasses. This was also the conclusion and recommendation of

scientists attending the International Seagrass Workshop in Kominato,

Japan in August 1993.

NMFS believes that Johnson's seagrass needs the additional

protection of listing, including consideration of effects of Federal

actions on the species through the section 7 consultation process of

the ESA. During consultation with other Federal agencies, NMFS can

ensure that any federally funded, permitted, or authorized activity

includes adequate measures to reduce adverse impacts from these

activities and to prevent jeopardizing the continued existence of the

species.

Issue 13: One commenter wrote that NMFS had exceeded the time

limit for making a final determination after proposing to list

Johnson's seagrass as threatened in 1993.

NMFS Response: In 1989, NMFS was notified by the FWS that it had

received information indicating that H. johnsonii was a rare species

which may need to be listed under the ESA. By 1993, NMFS had gathered

enough information to propose listing the species as threatened. In

1994, NMFS proposed critical habitat for the species. A joint public

hearing was held on both the proposed listing and proposed critical

habitat. The proposed critical habitat designation was very

controversial. Because of the controversy and new NMFS/FWS polices on

listing, NMFS postponed the final listing decision until information

used to make the original proposal had been peer reviewed and

additional information gathered. Peer review of the original

information and the results of new studies confirmed NMFS' original

determination that the species should be listed as threatened. The new

information was reviewed at a technical workshop in November 1996, and

summarized in a report in October 1997. In addition to gathering new

information, the final listing was delayed by the year-long

Congressionally imposed moratorium on listing species in fiscal year

1996.

Summary of the Factors Affecting the Species

After a thorough review and consideration of all information

available, NMFS concludes that H. johnsonii warrants listing as a

threatened species. Procedures found at section 4(a)(1) of the ESA (16

U.S.C. 1531 et seq.) and regulations (50 CFR part 424) promulgated to

implement the listing provisions of the ESA were followed. A species

may be determined to be endangered or threatened due to one or more of

the five factors described in section 4(a)(1). These factors and their

application to H. johnsonii are as follows:

1. Present or Threatened Destruction, Modification or Curtailment

of its Habitat or Range.

Habitat within the limited range in which H. johnsonii exists is at

risk of destruction by a number of human and natural perturbations

including (1) dredging; (2) prop scoring; (3) storm surge; (4) altered

water quality; and (5) siltation. Due to the fragile nature of H.

johnsonii's shallow root system, the plants are vulnerable to human-

induced disturbances in addition to the major natural disturbances to

the sediment, and their potential for recovery may be limited.

Destruction of benthic communities due to boating activities (propeller

scarring and anchor mooring) was observed at all H. johnsonii sites

during the NMFS study. Further, this condition is expected to worsen

with the predicted increase in boating activity. This severely disrupts

the benthic habitat by breaching root systems and severing rhizomes,

and significantly reducing the viability of the community.

Turbidity is a critical factor in the distribution and survival of

seagrasses, especially in deeper regions of the lagoon, where reduced

PAR limits photosynthesis. Shallow regions are less affected by

turbidity unless light is rapidly attenuated. In interior lagoonal

areas where salinity is low, highly colored water typically is

discharged via drainage systems. Stained waters attenuate shorter

wavelengths rapidly, removing important PAR as well as potentially

stressing plants due to the low salinity. This is a critical factor,

especially in the vicinity of Sebastian,

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St. Lucie, Jupiter, and Ft. Pierce Inlets, and Lake Worth and North

Biscayne Bay where freshwater reaches the flood tide delta and nearby

seagrass meadows via rivers and canal systems that discharge into the

lagoon.

Trampling due to human disturbance and increased land-use induced

siltation can threaten viability of the species. Degradation of water

quality due to human impact is also a threat to the welfare of seagrass

communities. Nutrient over-enrichment caused by inorganic and organic

nitrogen and phosphorous loading via urban and agricultural land run-

off can stimulate increased algal growth that may smother the

understory of H. johnsonii, shade rooted vegetation, and diminish the

oxygen content of the water. Such low oxygen conditions have a

demonstrated severe negative impact on seagrasses and associated

communities. Continued and increased degradation of environmental

quality also will have a detrimental effect upon H. johnsonii

communities.

2. Overutilization for Commercial, Recreational, Scientific or

Educational Purposes.

Overutilization for these purposes has not been a documented factor

in the decline of this species.

3. Disease or Predation

There are two known herbivores that occur in the range of H.

johnsonii--the green sea turtle (Chelonia mydas), and the West Indian

manatee (Trichechus manatus), both of which feed upon the seagrass.

Herbivorous fish also feed upon the seagrass community. Predation

pressures alone are not likely to be a threat to the species existence.

4. The Inadequacy of Existing Regulatory Mechanisms.

Despite existing Federal and Florida state laws to conserve and

protect seagrass habitat, there is a continued and well-documented loss

of seagrass habitat in the United States and elsewhere. For example,

seagrasses have declined in many areas of the Indian River Lagoon

(Virnstein and Morris, 1996). The Florida Department of Natural

Resources and the Florida Department of Environmental Regulation have

recently merged, greatly increasing the assignment of enforcement

responsibilities without an associated increase in staff for the Marine

Patrol. Although stormwater management systems are installed or being

installed, the Florida Indian River Lagoon Act of 1990 does not cover

other large inputs that will affect water quality, which in turn could

affect seagrasses (e.g. industrial discharges, brine disposal, canals,

processing plants).