. CAe: R,

F- 3~149

NOAA Technical Memorandum

NMFS - SEFC - 279

MAN - MADE MARINE DEBRIS AND SEA TURTLE

STRANDINGS ON BEACHES OF THE UPPER

TEXAS AND SOUTHWESTERN LOUISIANA

COASTS, JUNE 1987 THROUGH SEPTEMBER 1989

GALVESTON LABORATORY

SOUTHEAST FISHERIES CENTER

NATIONAL MARINE FISHERIES SERVICE

FEBRUARY 1991 NATIONAL OCEANIC AND ATMOSPHERIC

ADMINISTRATION

DEPARTMENT OF COMMERCE
NOAA TECHNICAL MEMORANDUM

NMFS-SEFC ..279

MAN - MADE MARINE DEBRIS AND SEA TURTLE

STRANDINGS ON BEACHES OF THE UPPER

TEXAS AND SOUTHWESTERN LOUISIANA

COASTS, JUNE 1987 THROUGH SEPTEMBER 1989

BY

Marcel J. Duronslet, Dickie B. Revera and Kerry M. Stanley

U.S. DEPARTMENT OF COMMERCE

Robert A. Mosbacher, Secretary

"- NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

John A. Knauss, Administrator

NATIONAL MARINE FISHERIES SERVICE

William W. Fox, Jr., Assistant Administrator for Fisheries

FEBRUARY 1991

This Technical Memorandum series is used for documentation and timely communication

of preliminary results, interim reports, or similar special-purpose information. Although

the memoranda are not subject to complete formal review, editorial control, or detailed

editing, they are expected to reflect sound professional work.
INTRODUCTION

Documentation of strandings of sea turtles on beaches in the

southeastern United states provides an important index of the numbers

of sea turtles that become ill, injured, stressed or killed by man's

activities or natural causes at sea. There are numerous documented

causes of sea turtle injury or mortality at sea (Coston-Clements and

Hoss, 1983; Conner, 1987; Henwood and stuntz, 1987; Heinly et al.,

1988; Manzella, Caillouet and Fontaine, 1988; Thompson, 1988; Murphy

and Hopkins-Murphy, 1989; Ross et al., 1989) including ingestion of or

entanglement in man-made marine debris (Balazs, 1985; Carr, 1986a,

1986b, 1987; Plotkin and Amos, 1988; Ruckdeschel and Shoop, 1988:

Stanley, stabenau and Landry, 1988).

In Autumn 1985, unprecedented strandings of sea turtles occurred on

the upper Texas coast (Schroeder, 1987). This upsurge in strandings was

attributed to use of explosives in salvaging petroleum platforms from

waters of the northwestern Gulf of Mexico (Klima, Gitschlag and Renaud,

1988), and it emphasized the need for an intensified, systematic, beach

sampling survey with the objectives of building a multi-year data base

to document year-round, temporal-spatial distribution of sea turtle

strandings as well as their possible causes. Such a multi-year data

base on strandings, entanglement and ingestion of marine debris could

contribute significantly to assessments of impacts of federal

regulations aimed at reducing at-sea mortality in sea turtles.

The sea turtle carcasses themselves represent a kind of "marine

debris" along with carcasses of fishes, jelly fishes,. birds and other

animals commonly found on beaches. Large numbers of sick, injured or

dead animals on beaches are symptomatic of the frequent hazards, both

natural and anthropogenic, that these animals are encountering.

This project represents one means of testing the working null

hypothesis that sea turtle strandings are not related to man's

activities at sea. There are a number of assumptions underlying the

testing of this hypothesis, including but not limited to the following:

(1) that those who take sea turtles incidentally (e.g., in commercial

or recreational fishing ventures or when using explosives for petroleum

platform removal, would not mutilate the carcasses in a manner that

would prevent them from floating onto a beach, (2) that stranded sea

turtles would exhibit evidence of natural or man-caused trauma, (e.g.

shark attacks) ingestion of or entanglement in marine debris etc.), (3)

that strandings and marine debris on a given beach reflect impacts

within the adjacent coastal waters, and (4) that at-sea strandings

represent a significant portion of total sea turtle mortalities.

The purposes of this study were (1) To document strandings of sea

turtles, (2) to document types and amounts of man-made marine debris,

and (3) to examine the relationship between strandings and man-made

marine debris along the coastlines of Texas and southwestern Louisiana.

1
MATERIALS AND METHODS

Monthly documentation of marine debris and entanglement of sea

turtles on beaches of the upper Texas and southwestern Louisiana coasts

was coupled with semi-monthly surveys of sea turtle strandings from

June 1987 through September 1989. This coupling offered one of the

simplest and most cost-effective ways of determining temporal-spatial

distribution and year to year trends in amounts of marine debris, sea

turtle strandings and sea turtle entanglement and debris ingestion.

The NMFS Sea Turtle stranding and Salvage Network (STSSN) has had a

voluntary reporting system in place since 1980, to document temporalspatial distributiQn ~nd trends in strandings (Schroeder, 1989; Teas

and Martinez, 1989). Systematic monthly coverage of sea turtle

strandings by the NMFS Galveston Laboratory was started in March 1986.

This increased the chances that stranded turtles were found before they

were redistributed by tides or destroyed by decomposition and carrion

feeders. More frequent sampling would have been desirable, but monthly

surveys of strandings and marine debris and entanglement were

considered adequate when conducted in a consistent year-round manner.

Marine Debris surveys

Beaches on the upper Texas and southwestern Louisiana coasts were

divided.into six sampling zones or strata (Figure 1), each of which was

usually surveyed once per month year-round for man-made marine debris

and sea turtle entanglements. Portions of zones 4 and 5 were routinely

cleaned by state or local government authorities, whereas zones 1-3 and

6 were not cleaned. Sampling both zone types provided an opportunity

to compare cleaned and uncleaned zones with regard to amounts and

rates of accumulation of marine debris. Cleaned zones would be

expected to provide a measure of short term accumulation of debris,

whereas sampling in uncleaned zones would measure longer term

accumulation.

sampling protocol within all six zones was based on that suggested

by the American Littoral Society (unpublished and distributed by

American Littoral Society, Sandy Hook, NJ). In cleaned zones 4 and 5,

locations of three foreshore plots were chosen each month using a

random numbers table to determine each plot's location at a randomly

chosen distance from a zone boundary. New locations of these plots

were randomly chosen each month. Locations of two foreshore plots in

each uncleaned zone (1-3 and 6), were randomly chosen each month by the

same procedure. In addition, one fixed foreshore plot and one abutting

fixed backshore plot (Figure 1) were established in each uncleaned zone

to assess debris accumulation between sampling intervals. The locations

of fixed plots were randomly selected at the beginning of the study.

Each foreshore plot was 3.3 m wide and extended from the waterline

to the first storm line or, if no storm line was present, 8.1 m

landward of the high tide line (Figures 2 and 3). While the width of

2
the plots was constant, the lengths varied from 2.7 to 69.2 m depending

on the position of the first storm line and tide stage. The total area

per plot therefore was different for each sample. In uncleaned zones

1-3 and 6, the additional backshore plot associated with each fixed

foreshore plot was also 3.3 m wide and extended landward from the first

storm line to the base of the foredune. Backshore plots were of

variable lengths also (2.4 to 53.8 m) depending on positions of the

first storm line and foredune. The boundaries of each plot were marked

with stakes and connecting lines.

Marine debris sampling included measuring and photographing each

plot followed by collection of all man-made items within the plot

boundaries. Debris items were stored in labeled plastic bags and taken

to the laboratory where they were categorized, enumerated and weighed.

Nine major categories of marine debris were recognized: plastic,

polystyrene foam (styrofoamTM), tar balls, glass, metal, rubber, paper,

wood and miscellaneous. Weights recorded for most debris items were

slightly biased upwards because of adhering sand particles. Every

attempt was made to remove excess sand particles before weights were

taken. Weights of wooden items also were biased upwards because of

high moisture content. In some cases, wooden items too large to weigh

(e.g., parts of boats, pallets, large planks, etc.) were measured and

described and dimensions and descriptions recorded, so these could

later be converted to weight estimated roughly by weight:volume ratio.

Natural debris items (tree trunks, detached grasses and animal

carcasses, except for sea turtles) were not included in the samples.

To accommodate differences in plot size due to variations in

characteristics of the beach profile and variations in tide stage at

the time and place of sampling, the area of each plot was calculated,

and the counts and weights of debris items were expressed in numbers or

kilograms per 100 m

2

, respectively. 'When a debris category was not

represented in the sample from a given plot in a given month zeros were

included in the monthly average density for that category.

From June 1987 through September 1989, marine debris was collected

from a total of 473 plots (Table 1). This included 181 randomly

located foreshore plots, 85 fixed foreshore plots and 87 fixed

backshore plots from uncleaned zones 1-3 and 6, and 120 randomly

located foreshore plots from cleaned zones 4 and 5. occasionally, some

plots could not be sampled as planned (e.g., high tides, large

quantities of sargassum weed on the beaches (May, June and JUly, 1989),

mechanical problems with 4 wheel-drive vehicles and insufficient

personnel resources from time to time). This produced considerable

imbalance in the data set (Table 1)..

statistical analyses were performed with SAS~ for personal

computers (SAS Institute, Inc., Cary, NC). Descriptive statistics

(mean, X, and variance, s2) were calculated for three variables derived

from the marine debris data: (1) area of the sampling plot (in 100 m

2

units), (2) number of debris items (all types combined) per 100 m

2 and

3
(3) weight of debris items (all types combined) per 100 m

2

, by year,

month and zone. Only the randomly located foreshore plots were

included in these analyses.

To determine whether the number per 100 m

2and weight per 100 m

2

needed transformation prior to parametric analysis, we deleted all

cases in which the number of randomly located foreshore plots was less

than two (in a given year-month-location combination) and regressed

In(s2) on In(X) , (Figures 4 and 5). Slopes of these lines were close to

2 so a logarithmic transformation was necessary to normalize the number

and weight of debris items per 100 m

2 (Taylor, 1961). Similar

transformations were applied to debris counts and weights for backshore

and fixed foreshore plots.

Because of the imbalance in the data set (Tables 1 and 2), we

conducted general linear model analyses of the transformed number per

100 m

2 and transformed weight per 100 m

2

, instead of analyses of

variance.

stranding, Entanglement And Inqestion Surveys

The NMFS Galveston Laboratory participated in STSSN surveys of the

entire Texas and southwestern Louisiana coasts, from the Rio Grande

River, Texas to the Mermentau River, Louisiana during the study. This

report includes only strandings from those .:portionsof the Texas and

Louisiana coasts covered by our debris survey. Beaches were traversed

at least once each month using 4-wheel-drive vehicles, 4-wheel allterrain-vehicles, or dirt. bikes, depending upon remoteness and

accessibility. Surveyed beaches were accessible barrier beaches

bordering the Gulf of Mexico from Pass Cavallo, Texas to Calcasieu

Pass, Louisiana (Figure 1; Table 2). Overwater transportation was

required to gain access to some barrier beaches (e.g., west Matagorda

Peninsula and Matagorda Island).

The NMFS beach surveyors also responded to reports of strandings

from other agencies and from the general public. These carcasses were

treated in the same manner as those found on routine surveys.

When a stranded sea turtle was found, species, size, sex, location,

condition, external injuries, mutilations, fouling (including

entanglement) and abnormalities were recorded on standardized STSSN

stranding reports (field data forms; Schroeder, 1989). If a stranding

involved entanglement, the type and possible source of entangling

material was identified. Amount and size, diameter or length of the

entangling material were recorded and photographs taken.

Carcasses were collected and transferred to Texas A&M University for

necropsy and gastrointestinal content analysis to provide additional

information on incidence of injuries, mutilations, propeller wounds,

entanglement in discarded fishing gear or debris, diseases, fouling by

oil or barnacles, ingestion of tar or debris, and papillomas or other

abnormalities (Heinly et al.,198B; Plotkin and Amos, 1988; Schroeder,

4
1988; Stanley, Stabenau and Landry, 1988). Necropsies were performed

according to Wolke and George (1981).

RESULTS

Karine Debris

Mean areas of randomly located foreshore plots by year month and

location are given in Table 3. A GLM analysis of these areas is

presented in Table 4. Plot mean areas were lowest (44.4 m

2) in April

and were significantly higher (90.0 m

2

) in October. Plot sizes were

significantly different by zones also, and varied from a mean of 56.6

m

2 in zone 5 to 77.0 m

2 in zone 1.

Arithmetic mean number of debris items per 100 m

2 is presented by

zone, year and month in Table 5. Zone, year and month had significant

effects on number of debris items per 100 m

2 (Table 6). The year (1987)

.with the fewest number (78) of random plots sampled had the highest

mean number of items per 100 m

2 (72.7). The lowest mean number of items

per 100 m

2 (32.0) occurred in 1989. with respect to samplin~ zone,

uncleaned zone 3 had the highest number of items per 100 m (104.6)

and uncleaned zone 6 the fewest (33.1). The average number of debris

items per 100 m

2 was lowest in the winter months, November through

February (16.2 - 34.2), rose in April and May and peaked in August

(155.6).

Mean weight of debris items collected per 100 m

2 is presented by

year, month and zone in Table 7. A GLM analysis of debris weights

(Table 8) indicated a significant difference in average kilograms per

100 m

2 for month and sample zones. Weights were lowest in winter months

November, December, January and February (0.143 - 0.246) and peaked in

May (1.121 kgs per 100 m

2

). Uncleaned zone 3 had the highest average

weights per 100 m

2

(1.461) while cleaned zone 4 had the lowest (0.158).

When numbers and weights of debris items from uncleaned zones were

compared to those from cleaned zones, the mean number of debris items

per 100 m

2 was reduced (64.6 to 49.2) but the difference was not

significant. There was, however, a significant reduction in mean

weight per 100 m

2 (0.514 kgs from uncleaned zones to 0.243 kgs from

cleaned zones).

Areas of fixed foreshore and backshore plots are presented in tables

9 and 10 respectively. Results of a GLM analysis of plot area for

fixed foreshore and fixed backshore plots are presented in tables 11

and 12. There was no difference in foreshore plot sizes by year, zone

or plots within zones. There was a difference based on month of the

year where plot areas varied from a low 50.9 m

2 in April to a high of

99.5 m

2 in November (Table 11).

The areas of fixed backshore plots varied significantly only by

sampling zone. Plot area was lowest (41.4 m

2

) in zone 3 and highest

(119.4 m

2

) in zone 1.

5
When examined by year or location, no differences were detected in

rate (number or weight) of debris accumulation in fixed foreshore or

backshore plots. When examined by month of the year (Table 13) there

was no difference in the number of items that accumulated per day, in

foreshore or backshore plots. In May, June and July, however, foreshore

Ptots accumulated significantly higher weights (0.094 - 0.305 kg/100

m /day) of marine debris. The rate of debris accumulation by weight in

these plots was lowest in November (0.003 kg/100 m

2/day). There was no

difference in mean weight accumulation by month in backshore plots

(Table 13).

Tarballs had the highest percentages by number per 100 m

2 among the

nine major debris categories (Figure 6) in cleaned (47.9%) and

uncleaned (73.9%) zones, followed by plastic (25.2% and 14.4%,

respectively).

Dominant debris types, in percentages by weight per 100 m

2, varied

between cleaned and uncleaned zones (Figure 6). In the cleaned zones

miscellaneous items (70.7%) dominated, followed by plastic (9.4%). In

uncleaned zones wooden items (69.8%) replaced miscellaneous items as

the dominant debris type, but were followed by plastic (15.3%).

When examined by sampling zone (Table 14), tar balls and plastic

items ranked first and second respectively in number of items collected

in every zone except zone 6. In this zone the two categories ranked

second and first respectively. styrofoamTM and glass items alternated

among zones for the third and fourth most frequently collected item.

Despite the fact that tar balls were the most frequently collected

debris item, their average weight (1.7 g per item) was next to the

lowest average weight (Table 15). styrofoamTM had the lowest average

weights (1.6 g per item) of all debris categories. The heaviest items

were wood (919.8 g per item) followed by miscellaneous (241.3 g per

item) and rubber (143.3 g per item). The high average weights for

miscellaneous items were attributed to asphalt, tile, concrete and

brick collected primarily from cleaned zones 4 and 5.

Btrandings

During STSSN surveys conducted from June 1987 through September 1989

in marine debris survey zones 1-6, 171 stranded sea turtles were found

(Table 16). Most of the strandings occurred in study zones 4 and 5 (49

and 57 respectively). The smallest number of strandings was recorded in

zone 3 (12).

Nine of the 171 strandings were live strandings (Table 17). Of the

162 carcasses that remained 32 have been analyzed for gastrointestinal

tract contents. Seventy three were too decomposed for gut content

analysis and 57 are awaiting examination. Nineteen of the 32 thus far

examined contained ingested marine debris (Table 18). Ingested

materials were of many types but plastics were dominant. None of the

6
ingested materials were judged to have caused the sea turtle's demise.

six of the 171 stranded sea turtles were entangled in man-made

materials (Table 19). No entangling events were recorded in study zones

2 or 6. One each was recorded in zones 1 and 3 while zones 4 and 5

each had 2 entanglements. Two of the 6 entanglements (1 in zone 4, 1 in

zone 5) involved discarded ropes. Both of these turtles were dead when

found. It was not possible to attribute either death to entanglement.

The remaining 4 entanglements involved live animals, entangled one each

in a shredded plastic bag, monofilament fishing line, a fish hook and

the intake screen of an electrical power plant.

Tables 20 and 21 summarize strandings along surveyed beaches in

zones 1-6 from June 1987-September 1989, by year and month. Stranding

levels remained relatively stable from year to year (Table 20). May

was the peak month for strandings, but a minor secondary peak occurred

in August (Table 21). By species, loggerheads (Caretta caretta) and

kemp's ridleys (Lepidochelys kempi) dominated the strandings (Table

20). Other stranded turtles included leatherbacks (Oermochelvs

coriacea) greens (Chelonia mydas) and hawksbills (Eretomochelvs

imbricata).

Nine of the total strandings documented in the study were livestrandings (Table 22). One animal was released immediately. A second

turtle required flipper amputation and can never exist in the wild.

Two died in captivity after attempts at rehabilitation failed. The

five remaining live stranded animals were all released back into the

wild after 0.5 to 10 months of rehabilitation.

SUMMARY AND DISCUSSION

strandings of hundreds of sea turtles on beaches bordering the

northwestern Gulf of Mexico each year are symptomatic of something

radically wrong in the coastal ecosystem of which sea turtles are a

part. Either man's at-sea activities or major changes in the biotic

and abiotic conditions within the sea turtles's natural environment or

both are stressing sea turtles and causing their mortalities.

Several causes for these mortalities have been identified including

shrimping activity, offshore petroleum operations, natural causes and

ingestion of or entanglement in man-made marine debris. By-catch in

shrimp trawls has been reported to be the major cause of sea turtle

mortalities (Liner, 1954; Cox and Mauermann, 1976; Magnuson et al.,

1990). The extent of involvement of the remaining causes has not been

well defined. This study was undertaken to quantify the number of sea

turtle deaths caused by man-made marine debris and describe the amount,

type and variability of this debris in a specific locale.

width of individual marine debris sample plots were constant but

lengths, hence areas sampled, varied because of differences in tide

stage at the time of sampling. Mean areas sampled were significantly

7
higher in the winter months (Table 4). This was expected as lower

tides are more frequent in wintertime, caused by an increase in the

number and strength of northerly winds. There was no significant

difference in mean area of sample plots between years. Because sample

area was not constant debris items were examined in terms of number and

weight'per 100 m

2 sampled.

Samples of marine debris and all dead or live stranded sea turtles

were collected over a 28 month period from 6 designated beaches.

Debris was categorized by type and amount present and sea turtles were

examined for any involvement with marine debris. Sea turtle carcasses

reported by the general public were also examined by investigators and

analyzed in conjunction with those found on routine surveys. It was

felt that the combination would more accurately represent total

mortalities and increase the chances of identifying marine debris

related deaths.

The significant difference detected in mean number of debris items

between years cannot be explained by this data. The difference may be

real or an artifact from sampling one entire year and only parts of two

others. This would have to be resolved by an extended sampling period

covering several years. The warmer summer months were also

significantly higher in mean number of debris items. This can be

accounted for if one assumes a higher degree of outdoor, marine related

activity by the general public in the warmer months of the year. This

higher activity level would generate increased levels of waste and

result in more debris on the beaches.

The mean number of debris items between zones ranged from 33 to 104

per 100 m

2

, with two uncleaned zones, 3 and 6, accounting for both the

highest and the lowest mean numbers (Table 6). Surprisingly, when

cleaned and uncleaned zones were grouped and compared to each other

there was a reduction, from uncleaned to cleaned, in mean number of

debris items but not a significant reduction. Mean weights, however,

were significantly reduced (Table 8). These findings could be the

result of two factors. First of all, debris surveyors collected,

counted and weighed all debris found which often resulted in large

numbers of very small and lightweight items (Tables 14-15). Secondly

it is entirely possible that cleaning crews, who generally work from

tractors, tend to remove only the unsightly, but larger and heavier

items from the beach. These factors combined would tend to minimally

affect a difference in numbers of items between the two zone types but

could dramatically affect mean weights.

When comparing rates of accumulation of man-made marine debris, from

fixed foreshore plots, (Table 13), rates were higher in the warmer

months of the year, May through August. Significant increases were

observed in weights of debris. This is in agreement with the concept

of higher levels of outdoor human activity during this time of year.

Rates of accumulation in fixedbackshore plots were variable with no

significant differences observed.

8
Marine debris and its detrimental effect on sea turtles can be

divided into two categories, entanglement and ingestion. Only 6 (3.5%;

Table 19) of all stranded animals documented in the study were

entangled 'or externally associated with man-made materials. Even

though the loss of one endangered or threatened animal is unacceptable,

possibly affecting the species' ultimate survival, this percentage

cannot be viewed as very high. On the other hand, 59.4% of all

carcasses that could be examined (Table 18) had gastrointestinal

contents that included some type of man-made marine debris. It could

not be determined if the ingested materials caused the deaths or

strandings. The amounts, types and possible effects of these ingested

materials is the subject of another report in preparation.

ACKNOWLEDGEMENTS

Our marine debris, entanglement and stranding surveys involved the

direct or indirect participation of other Federal and state agencies,

universities,private industries, oceanaria, conservation organizations

and the general public. NMFS, FWS, NPS, and TPWD employees

participated in the STSSN as well as faculty and graduate and

undergraduate students from Texas A&M University at Galveston, Texas

A&M University at College station, the Texas Veterinary Medical

Diagnostic Laboratory Systems, Pan American university, McNeese state

University, and the university of Texas Marine science Institute.

NMFS' work was closely coordinated wit.h other agencies and

organizations such as the Texas General Land Office's "Adopt-a-Beach"

program and the Center for Marine Conservation's annual Texas Coastal

Cleanup. The'·NMFS Kemp's Ridley Sea Turtle Head start Experiment and

several cooperating oceanaria were involved in rehabilitating livestranded and injured animals collected in the survey area (e.g., SeaArama Marineworld, Sea Turtle Incorporated, University of Texas Marine

Science Institute).

We are grateful to Dr. Andre Landry, Texas A&M University,and his

graduate students for their participation and assistance in developing

and carrying out these surveys.

9
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and ingestion. In: Shomura, R.S. and H. O. Yoshido (Editors),

Proceedings of the Workshop on the Fate and Impact of Marine Debris,

NOAA Tech Memo NMFS-SWFC-54. P. 387-429.

Carr, A. 1986a. Rips, FADS and little loggerheads. BioScience 26:92-100.

Carr, A. 1986b. New perspectives on the pelagic stage of sea turtle

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Cox, B. A. and R. G. Mauermann. 1976. Incidental catch and disposition of

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10
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1987 Results, p. 99-101. In: Schroeder, B. A. (Compiler),

Proceedings of the Eighth Annual WorkshOp on Sea Turtle Conservation

and BiOlogy, NOAA Tech Memo NMFS-SEFC-214, 136 p.

Schroeder, B. A. 1989. Marine turtle data base management: National

Marine Fisheries Service - Miami Laboratory, p153-156. In: Caillouet,

C. W., Jr. and A. M. Landry, Jr. (Editors), Proceedings of the First

International Symposium on Kemp's Ridley Sea Turtle BiOlogy,

Conservation and Management. Tex.A&M Univ., Sea Grant College Program

TAMU-SG-89-105, vi plus 262 p.

Stanley, K. M., E. K. Stabenau and A. M. Landry. 1988. Debris ingestion

by sea turtles along the Texas coast, p. 119-121. In: Schroeder, B.

A. (Compiler), Proceedings of the Eighth Annual Workshop on Sea Turtle

Conservation and Biology, NOAA Tech Memo NMFS-SEFC-214, 136 p.

Taylor, L. R. 1961. Aggregation, variance and the mean. Nature. 189:

11
732-735.

Thompson, N. B. 1988. The status of loggerhead, Caretta; Kemp's ridley,

Lepidochelys kempi; and green,Chelonia mvdas, sea turtles in u.s.

waters. Mar Fish Rev 50(3):16-23.

Wolke, R. E. and A. George. 1981. Sea Turtle Necropsy Manual, NOAA Tech

Memo NMFS-SEFC-24, 20 p.

12
Table 1. Temporal-spatial sampling of marine debris from June 1987 through

September 19898•

Zones

Uncleaned Cleaned Uncleaned

1 2 3 4 5 6 No. of plots

Year Month 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 1 2 3 1 2 3 4 sampled

1987 Jun S S S S S S S S S S S S S S S S S S S S S S 22

Jul S S S S S S S S S S S S S S S S S S S S S S 22

Aug S S S S S S S S S S S S S S S S S S S S S S 22

Sep S S S S S S S S S N S S N N N N N N N N N N 11

Oct S S S S S S S S S S S S S S S S S S N N N S 19

Nov S S S S S S S S S S S S S S* S S S S S S N N 20

Dec S N S S S S N N S S S S N N N N N N N N N N 9

Subtotal

of samples

767 7 7 766 767 7

13

555 555 4 4 3 4 125
Table 1. (continued)

Year Month 1 2

1

3 4

Uncleaned

2

1 2 3 4 1 2

Zones

4 1

4

2

Cleaned

3 1

5

2 3

Uncleaned

6

1 2 3 4

No. of plots

sampled

1988 Jan S* S S S S S S S S S S S S S S S S S S N N N 19

Feb

Mar

Apr

May

S N S S

S S S S

S S N S

S S S S

N S S S

S S S S

S S S S

S N S S

S N N N

S S S S

S S S S

S S S S

S S S

S S S

N N N

S S S

NNN NNNN

S S S N N N N

NNN NNNN

NNN NNNN

11

18

11

\

14

Jun S S S S S S S S S S S S N N N N N N N N N N 12

Jul

Aug

Sep

Oct

Nov

Dec

S S S S

S S S S

S S S S

S S S S

S S S S

S S S S

S S S S

S S S S

S S S S

S S S S

S S S S

S S S S

S S S S N N N

S S S S S S S

S S S S S S S

N N N N S S S

S S S S S S S

N N N N S S S

NNN NNNN

S S S S S S S

S S S S S S S

S S S S S S S

S S S S S S S

N N N S S S S

12

22

22

18

22

15

Subtotal 12 11 11 12 12 11 12 12 10 9 9 9

of samples

14

999 666 6 5 5 5 196
Table 1. (continued)

Year Month 1 2 4

Uncleaned

2

1 2 3 4 1 2

3

3

Zones

4 1

4

2

Cleaned

3 1

5

2 3

Uncleaned

6

123 4

No. of plots

sampled

1989 Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Subtotal

of samples

S S S S

S S S S

S S S S

S S S S

N N N N

N N N N

S N S S

S S S S

S S S S

7 677

S S N N

S S S S

S S N S

S S S S

N N N N

N N N N

S S S S

S S S S

S S S S

7 7 5 6

S S S N

S S S S

S S S S

S S S S

N N N N

N N N N

S S S S

S S S S

S S S S

7 7 7 6

S S S

S S S

S S S

S S S

S S S

S S S

N N N

S S S

N N N

777

S S S

s* S S

S S S

S ,S S

S 'S S

N N N

S S S

S S S

S S S

888)

S S* S* S

S S S S

S S S S

S S S S

S S S S

S S N N

N N N N

S S N N

S S S S

8 8 6 6

19

22

21

22

10

5

14

20

19

152

Grand Total 26 24 25 26 26 25 23 24 24 22 23 22 21 21 21 19 19 19 18 17 14 15 473

a Plots 1 and 2 in Zones 1-6 were randomly located foreshore plots; plot 3 in Zones 4-5 was a

randomly located foreshore plot; plot 3 in Zones 1-3 and 6 was a fixed foreshore plot; and

plot 4 was a fixed backshore plot landward of plot 3 in Zones 1-3 and 6. S = sampled; N = not

sampled; and * = no debris in sample.

15
Table 2. Lengths of zones

8

(or strata) surveyed for sea turtle strandings

and entanglement on the upper Texas and southwestern Louisiana

coasts from June 1987 through September 1989.

Total length Length of

Zone8

km surveyed beach km Percent

1 38.34 38.34 100

2 41. 20 38.14 92.6

3 20.00 19.15 95.8

4 68.51 66.67 97.3

5 99.83 75.8 75.9

6 4g.44 43.13 87.2

Total 327.64 281.23 85.84

8 These zones are the same as those in which debris sampling plots, both

random and fixed, were established.

16
Table 3. Mean area (in 100 m

2 units) randomly located foreshore plots from June 1987

through September 1989.

Zones

Uncleaned Cleaned Uncleaned

1 2 3 4 5 6

Year Month

1987 Jun 1.07 0.76 0.53 0.46 0.43 0.57

Jul 0.77 0.52 0.52 0.26 0.12 0.52

Aug 0.83 0.76 0.66 0.64 0.18 0.49

Sep 0.78 0.85 0.65* N N N

Oct 0.92 1.14 1.06 1.24 0.53 N

Nov 1.15 0.87 1.50 0.50 0.92 0.46

Dec 1.06* 0.83 0.81 N N N

1988 Jan 0.63 0.62 0.33 1.10 0.59 1.72*

Feb 0.77* 0.64 0.29* 0.62 N N

Mar 0.52 0.50 0.37 0.53 0.61 N

Apr 0.50 0.45 0.41 N N N

May 0.59 0.39* 0.89 0.57 N N

Jun 0.48 0.39 0.63 N N N

Jul 0.71 0.55 0.51 N N N

Aug 0.33 0.66 0.68 0.50 0.34 0.86

SeD 1.71 1.16 0.61 0.83 0.71 0.56

17
Table 3 (conti d)

Zones

Uncleaned Cleaned Uncleaned

1 2 3 4 5 6

Year Month

1988 Oct 0.48 0.62 N 1.11 0.53 1.09

Nov 0.57 0.57 0.91 0.82 0.50 0.68

Dec 0.61 0.48 N 0.91 N 0.82

1989 Jan 0.96 0.74 0.86 0.87 0.66 0.48

Feb 1.54 0.53 0.73 0.50 1.16 0.49

Mar 0.76 0.42 0.39 0.57 0.84 0.73

Apr 0.43 0.59 0.47 0.51 0.37 0.45

May N N N 0.41 0.38 0.78

Jun N N N 0.82 N 0.79

Jul 0.64* 0.58 0.75 N 0.68 N

Aug 0.28 0.77 0.71 0.49 0.70 0.81

Sep 0.82 0.64 0.55 N 0.61 0.93

* Indicates only one sample plot represented; otherwise means for zones 1, 2, 3 and 6

.are for two sample plots; and means for zones 4 and 5 are for three sample plots.

N Indicates no sample taken.

18
Table 4. Results of general linear models (GLM) analysis

of mean area (in 100 m

2

" units) for randomly located

foreshore sample plots.

A Type IV GLM analysis8

Source of Degrees of Mean

variation freedom square F

Year 2 0.156 2.05

Month 11 0.453 5.94*

Zone 5 0.226 2.96*

Plots within zones 8 0.066 0.86

Residual 274 0.076

Total 300

B Least-Squares Means

Number Debris Items, Number Area in 100

Month of plots No/I00 m

2 Zone of plots m2 units

Jan 27 0.775 1 49 0.770

Feb 21 0.745 2 51 0.666

Mar 26 0.588 3 46 0.694

Apr 20 0.444 4 63 0.681

May 16 0.571 5 57 0.566

Jun 25 0.619 6 35 0.697

Jul 28 0.525

Aug 42 0.583

Sep 30 0.820

Oct 24 0.900

Nov 28 0.798

Dec 14 0.781

a Milliken and Johnson (1984).

* Indicates significant difference from zero at P <0.05.

19
Table 5. Mean number of debris items per 100 m

2

in randomly located foreshore plots.

Zones

Uncleaned Cleaned Uncleaned

1 2 3 4 5 6

Year Month

1987 Jun 29 450 651 289 84 60

Jul 79 153 25 540 42 212

Aug 182 352 258 132 246 28

Sep 59 185 91* N N N

Oct 18 98 287 82 43 N

Nov 30 42 37 7 14 93

Dec 2* 35 56 N N N

1988 Jan 13 69 79 86 41 20*

Feb 19* 42 59* 15 N N

Mar 245 30 48 45 70 N

Apr 62 37 125 N N N

May 69 109* 512 131 N N

Jun 73 71 73 N N N

Jul 236 298 503 N N N

Aug 985 1086 1821 459 119 85

Sep 128 49 21 47 104 16

20
Table 5. (cont'd) •

Zones

Uncleaned Cleaned Uncleaned

1 2 3 4 5 6

Year Month

1988 Oct 148 44 N 74 57 15

Nov 8 19 72 4 102 6

Dec 23 9 N 15 N 97

1989 Jan 10 4 250 13 48 1

Feb 37 44 57 53 5 21

Mar 73 15 79 44 20 15

Apr 379 154 225 29 52 43

May N N N 55 40 96

Jun N N N 24 N 33

Jul 47* 43 74 N 27 N

Aug 152 57 49 31 38 64

Sep 13 34 108 N 95 15

.* Indicates only one sample represented; otherwise means for zones 1, 2, 3 and 6 are

means of two samples; zones 4 and 5 are means of three samples.

N Indicates no sample taken.

21
Table 6. Results of general linear models (GLM) analysis

of transformed number of marine debris items

per 100 m

2

, for randomly located foreshore

sample plots.

A Type IV GLM analysis8

Souroe of Degrees of Mean

variation freedom square F

Year 2 15.005 10.73*

Month 11 12.455 8.91*

Zone 5 5.836 4.17*

Plots within zones 8 1.533 1.10

Residual 274 1.398

Total 300

B Detransformed Least-squares Meansb

Number

Year of plots

No. of Debris

items per 100 m

2 Month

Number

of plots

No. of Debris

items per 100 m

2

1987 78 72.7 Jan 27 32.6

1988 121 69.5 Feb 21 34.2

1989 102 32.0 Mar 26 51.4

Apr 20 100.2

Zone Number No. of debris May 16 114.4

of plots items per 100 m

2

Jun 25 92.2

Jul 28 94.7

1 49 56.0 Aug 42 155.6

2 51 60.0 Sep 30 52.2

3 46 104.6 Oct 24 49.0

4 63 47.6 Nov 28 16.2

5 57 47.4 Dec 14 17.8

6 35 33.1

8

Milliken and Johnson (1984) •

b

Antilog of (LSM-1) •

* Indicates significant difference from zero at P <0.05.

22
Table 7. Mean weight (kg) of debris items per 100 m

2

, in randomly located foreshore

plots.

Zones

Uncleaned Cleaned Uncleaned

1 2 3 4 5 6

Year Month

1987 Jun 0.13 0.69 2.07 0.40 0.03 0.30

Jul 0.06 0.37 0.10 1.56 0.53 1.36

Aug 0.44 5.48 2.72 0.25 0.24 0~25

Sep 0.03 1.85 3.14* N N N

Oct 0.13 5.85 5.61 0.43 0.68 N

Nov 0.20 0.79 3.64 0.03 0.38 0.42

Dec 0.00* 0.67 1.25 N N N

1988 Jan 0.03 3.22 1.99 0.91 0.88 0.21

Feb 0.01* 2.80 9.77* 0.03 N N

Mar 1.75 7.87 0.54 0.27 2.13 N

Apr 0.07 0.15 15.61 N N N

May 1.11 9.34* 13.89 0.09 N N

Jun 0.53 0.58 0.71 N N N

Jul 0.78 2.29 2.24 N N· N

Aug 2.60 2.31 12.33 0.80 0.60 0.40

Sep 0.36 1.15 0.17 0.25 0.99 1.45

23
Table 7 (cont' d)

Zones

Uncleaned Cleaned Uncleaned

1 2 3 4 5 6

Year Month

1988 Oct 2.44 2.34 N 0.37 1.36 0.27

Nov 0.04 0.16 0.36 0.36 3.32 0.12

Dec 0.08 3.28 N 0.12 N 0.12

1989 Jan 0.23 0.31 1.05 0.05 1.21 0.07

Feb 2.13 3.95 0.29 0.51 0.05 0.01

Mar 1.32 3.58 0.99 1.95 0.68 0.81

Apr 0.41 5.04 5.75 0.02 0.74 0.25

May N N N 2.17 0.30 2.59·

Jun N N N 0.14 N 0.70

Jul 0.30* 0.67 0.52 N 3.97 N

Aug 0.35 1.04 2.54 1.27 1.03 0.77

Sep 0.28 3.07 21.10 N 2.50 0.07

* Indicates only one sample represented; otherwise means for zones 1, 2, 3 and 6 are

means of two samples; zones 4 and 5 are means of three samples.

N Indicates no sample taken.

24
Table 8. Results of general linear models (GLM) analysis

of transformed kilograms of marine debris

per 100 m

2

, in randomly located foreshore sample plots.

A Type IV GLK analysis a

Source of Degrees of Mean F

variation freedom sQUare

Year 2 2.674 0.72

Month 11 8.598 2.30*

Zone 5 43.329 11. 61*

Plots within zones 8 6.633 1.78

Residual 274 3.733

Total 300

B Detransformed Least-Squares Meansb

Number Weight (kg) of Number Weight (kg) of

Month of Plots debris items Zone of Plots debris items

per 100 m

2

per 1002

Jan 27 0.246 1 49 0.184

Feb 21 0.194 2 51 1.016

Mar 26 0.724 3 46 1.461

Apr 20 0.278 4 63 0.158

May 16 1.121 5 57 0.307

Jun 25 0.320 6 35 0.200

Jul 28 0.404

Aug 42 0.551

Sep 30 0.390

Oct 24 0.876

Nov 28 0.190

Dec 14 0.143

a Milliken and Johnson (1984).

b Antilog of (LSM-1).

* Indicates significant difference from zero at P <0.05

25
Table 9. Area in 100 m

2

units of fixed foreshore plots from

June 1987 through september 1989. Each month and

zone is represented by one sample plot.

Uncleaned zones

1 2 3 6

Year Month

1987 Jun 1.04 0.58 0.72 0.93

Jul 0.50 0.68 0.54 0.46

Aug 0.46 0.75 0.74 0.73

Sep 0.64 0.85 0.64 N

Oct 1.03 1.14 1.09 N

Nov 0.71 1.00 1.85 N

Dec 0.84 N 0.96 N

1988 Jan 0.62 1.00 0.49 N

Feb 0.97 0.63 N N

Mar 0.57 0.48 0.54 N

Apr N 0.38 0.42 N

May 0.36 0.70 0.66 N

Jun 0.35 0.40 0.58 N

Jul 0.73 0.80 0.54 N

Aug 0.34 0.64 0.51 0.82

Sep 1.48 0.68 0.52 0.53

Oct 0.85 0.71 N 0.92

Nov 0.65 0.60 1.07 1.17

Dec 0.56 0.57 N 1.10

26
Table 9 (oont'd).

Unoleaned zones

1 2 3 6

Year Month

1989 Jan 0.69 N 0.91 0.35

Feb 0.84 0.53 0.70 0.39

Mar 0.67 N 0.51 0.79

Apr 0.49 0.62 0.45 0.41

May N N N 0.77

Jun N N N N

Jul 0.42 0.54 0.74 N

Aug 0.27 0.50 0.59 N

Sep 0.89 0.59 0.56 0.85

N Indicates no sample taken.

27
Table 10. Area in 100 m

2 units of fixed backshore plots, from June 1987

through September 1989. Each month and zone is represented

by one sample plot.

Uncleaned zones

1 2 3 6

Year Month

1987 Jun 1.27 0.65 0.22 1.34

Jul 1.43 0.81 0.73 1.01

Aug 1.53 1.07 0.74 1.61

Sep 1.60 0.63 0.63 N

Oct 0.89 0.78 0.29 0.98

Nov 1.24 0.96 0.44 N

Dec 0.77 N 0.39 N

1988 Jan 1.27 0.48 0.55 N

Feb 0.83 0.12 N N

Mar 1.04 0.43 0.51 N

Apr 0.99 0.68 0.41 N

May 1.50 0.60 0.43 N

Jun 1.30 0.57 0.38 N

Jul 1.33 0.25 0.26 N

Aug 1.77 0.85 0.46 0.62

Sep 1.19 1.28 1.26 0.59

Oct 1.16 1.09 N 0.52

Nov 1.13 1.11 0.32 0.67

Dec 1.34 1.44 N 0.70

N Indicates no sample taken.
Table 10 (cont'd)

Uncleaned zones

1 2 3 6

Year Month

1989 Jan 0.97 N N 0.98

Feb 0.82 0.90 0.21 1.78

Mar 1.12 0.69 0.37 0.99

Apr 0.43 0.31 0.13 0.83

May N N N 0.99

Jun N N N N

Jul 1.23 0.94 0.10 N

Aug 1.77 0.69 0.64 N

Sep 1.27 1.25 0.08 0.66

* Indicates no sample taken.

29
Table 11. Results of general linear models (GLM) analysis of

area (in 100 m

2

units) for fixed foreshore sample

plots.

A Type IV GLH analysis8

Source of

variation

Degrees of

freedom

Hean

sgy,are F

Year 2

Month 11

Zone 3

Plots within zones 0

Residual 68

Total 84

0.120

0.137

0.024

0.052

2.32

2.64*

0.46

B Least-Squares Heans

Number Area in 100 m

2

Month of plots units

Jan 6 0.722

Feb 6 0.734

Mar 6 0.642

Apr 6 0.509

May 4 0.669

Jun 7 0.629

Jul 10 0.593

Aug 11 0.576

Sep 11 0.760

Oct 6 0.942

Nov 7 0.995

Dec 5 0.804

8

*

Milliken and Johnson (1984).

Indicates significant difference from zero at P <0.05.

30
Table 12. Results of general linear models (GLM) analysis

of area (in 100 m

2

units) for fixed backshore

sample plots.

A Type IV GLM analysis8

Source of

variation

Year

Month

Zone

Degrees of

freedom

2

11

3

Mean

sauare

0.047

0.126

2.466

F

0.49

1.31

25.67*

Plots within zones 0

Residual

Total

B Least-Squares Means

70

86

.096

Zone

1

2

3

6

Number of

plots

26

24

22

15

Area in 100 m

2

units

1.194

0.769

0.414

0.940

8 Milliken and Johnson (1984).

* Indicates significant difference from zero at P <0.05.

31
Table 13. Least-squares means, accumulation rates of marine debris, in

permanently located foreshore and backshore plots.

Foreshore Backshore

Month No. of debris

items per

100m2per day

Weight (kg) of

debris items per

100m2per day

No. of debris

items per

100m2per day

Weight (kg)

of debris

items per

100m2per

day

January 0.8 0.040 91.3 0.043

February 2.0 0.020 5.6 0.260

March 0.5 0.087 9.7 0.094

April 3.8 0.008 5.9 -0.061

May 9.3 0.276* 8.9 -0.134

June 9.6 0.305* 10.4 -0.220

July 23.7 0.094* 15.8 0.992

August 15.2 0.032 6.8 0.203

September 3.8 0.035 8.6 0.181

October 0.5 0.045 0.9 0.066

November -1.7 0.003 2.1 0.272

December -0.7 0.029 4.3 -0.030

* Indicates significant difference from zero at P <0.05.
Table 14. Total number of marine debris items per 100 m

2

in randomly located foreshore plots,

by zone and marine debris category, June 1987 through September 1989.

Zones

Debris Tvpe 1 2 3 4 5 6

Tar Balls 7282 7036 8062 4410 1662 885

Plastic 1135 925 1711 1678 1520 909

Styrofoam 559 670 585 399 346 240

Glass 83 202 889 422 918 50

Wood 66 74 157 52 93 38

Paper 28 32 61 143 62 88

Rubber 26 43 50 38 87 17

Metal 25 52 175 93 126 32

Miscellaneous 10 22 190 65 563 54

33
Table 15. Average weight (g) per item of marine

debris collected in randomly located

foreshore plots, June 1987 through

September 1989.

Debris Category Weiaht (gm)per item

Wood 919.8

Miscellaneous 241.3

Rubber 143.3

Metal 42.6

Plastic 19.1

Glass 17.0

Paper 7.6

Tar balls 1.7

Styrofoam 1.6

34
Table 16. Total number of sea turtles stranded on the upper Texas and southwestern

Louisiana coasts from June 1987 through september 1989, by species and

zone. The number of carcasses found on routine surveys is enclosed in parentheses.

Zones

8Decies 1 2 3 4 5 6 Total

Kemp's

ridley· 6 (6) 5 (2) 5 (3) 13 24 (2) 12 (9) 65 (22)

Loggerheads 8 (8) 5 (5) 2 (1) 30 (4) 21 (4) 3 (3) 69 (25)

Green 1 4 (1) 1 6 (1)

Leatherback 3 (3) 2 6 (2) 11 (5)

Hawksbill 1 (1) 1 2 (1)

Unknown 3 8 1 5 1 (1) 18 (1)

Total 19 (15) 18 (7) 12 (7) 49 (5) 57 (8) 16 (13) 171 (55)

35
Table 17. Number of live stranded sea turtles that stranded on

the upper Texas and southwestern Louisiana coasts from

June 1987 through September 1989, by species and

zone.

Zones

Species 1 2 3 4 5 6 Total

Kemp's 1 2 1 4

ridley

Loggerheads 2 2

Hawksbill 1 1 2

Unknown 1 1

Total 1 2

36

4 2 9
Table 18. Number of gastrointestinal tracts that contained marine debris/ and number

of tracts analyzed, from sea turtles that stranded on the upper Texas and

southwestern Louisiana coasts from June, 1987 through September, 1989 by

species and study zone. Parentheses indicate number of carcasses too

decomposed for gastrointestinal tract analysis.

Zones

species 1 2 3 4 5 6 Total

Kemp's

ridley 0/1 1/1 0/1 1/3 3/5 5/11

(2) (2) (4) (8) (10) (30)

Loggerheads 1/2 1/1 5/8 6/8 13/19

(2) (1) (1) (7) (6) (3) (22)

Green 1/1 1/1

(1) (2) (3)

Leatherback

(2) (1) (5) (2)

Hawksbill

(2)

Unknown 0/1 0/1

(3) (7) (1) (4) (1) (17)

Total 1/3

(6)

2/3

(10)

0/1

(6)

7/12

(14)

37

9/13

(23) (14)

19/32

(73)
Table 19. Numbers of sea turtles found entangled on beaches of the upper Texas and

southwestern Louisiana coasts from June 1987 through September 1989, by

entangling material and zone.

Zones

Entanglement 1 2 3 4 5 6 Total

Fish hook 1* 1

Monofilament 1* 1

Plastic bag 1* 1

Rope 1 1 2

Intake screen 1* 1

None 19 19 11 47 53 16 165

Total 20 19 12 49 55 16 171

* Indicates an entangled sea turtle that was alive when found.

38
Table 20. Sea turtle strandings on beaches of the upper Texas

and southwestern Louisiana coasts from June 1987

through September 1989, by species and year.

Species 1987 1988 1989 Total

Loggerhead 22 22 25 69

Kemp's Ridley 21 25 19 65

Green 1 5 6

Leatherback 1 7 3 11

Hawksbill 1 1 2

Unknown 12 4 2 18

Total 58 58 55 171

39
Table 21. Sea turtle strandings on beaches of the upper Texas and

southwestern Louisiana coasts from June 1987 through september

1989, by species and month.

s~ecies

Month

Kemp's

Loggerhead Ridley Green Leatherback Hawksbill Unknown Total

January 4 1 5

February 1 1 2

March 5 2 1 8

April 5 13 1 2 21

May 12 9 2 3 1 27

June 5 5 1 1 13

July 7 4 1 1 4 17

August 7 8 1 1 6 23

September 9 8 2 19

October 4 4 2 1 11

November 8 7 3 18

December 2 5 7

Total 69 65 6 11 2 18 171
Table 22. Disposition of sea turtles found live-stranded on beaches

of the upper Texas and southwestern Louisiana coasts from

June 1987 to September 1989.

Released

Released after Permanent Died in

Species immediately rehab. captive captivity Total

Kemp's

ridley 3 1 4

Hawksbill 1 1 2

Loggerhead 1 1 2

Unknown 1 1

Total 1 5 1 2 9

41
LOUISIANA

TEXAS

MATAGORDA

BAY

I

6

5

4

GULF OF HEX ICO

Figure 1. Geographic location of marine debris and sea turtle stranding

and salvage sampling zones. Asterisks (*) mark the location of

permanent debris sampling plots.

42
BEACH PROFILE

. .

" .

': .

· .

., ','

. .

.'.. ..

· .. '. ...

· ...

..

· .

·.

FIRST

t

DUNE

..

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....

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.·..

.... ·

....

. .

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...

.

. .

.....

·.

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.

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..

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,

' ...,

,.

..

.

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.:.... ::

.......

. ..

. ..

'..

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.. ,

...

'... .

..

WATER LINE

~

..

.:.'....,.,','

e, •• : •• ,e " .: ••• ' '.

..

r---v-a-ri-a-bl-e-L-e-n-g-th--->!< 8.1 M )1

\;-----* I' FORESHORE PLOT

Figure 2,

BACK SHORE

PLOT

Diagrammatic profile (cross-section) of coastal beach (adapted from American

Littoral Society, unpublished),

43
WATER LINE

<

IE» ::!.

IE»

~

CD

rCD

"

~

e

I/Q

:;0 -':7 ,.." V)

::J:

e

:;0,.."

"'tJ HIGH TIDE LINE

re _._--

-t

CJ)

::I

-l- 1st STORM LINE

----

OJ J> r-< "'tJO CD IE»

r-~ ~ ::!. eV) I/QIE» -t::J: -1:7 e

':7 __

:;0 CD ,.." -1- FOREDUNE -'- ----

t4- 3.3M ~

Figure 3. Diagram (plan view) of marine debris survey plot

(adapted from American Littoral Society, unpublished).

44
16

14

In (S2) = -1.77 + 2.10 [In (X)]

2

r = 0.692

12

n = 127

10

8 •

In (S2)

6

• ••• •

•••

4 • • • •

• •

•

• • •

2 •

•

0 •

• •

•

-2

0 1 2 3 4 5 6 7 8

In (X)

Figure 4. Plot of natural log variance vs. natural log mean for

number of debris items per 100 square meters of beach

sampled. Data are from randomly located foreshore plots

only, sampled from June 1987 through September 1989.

45
24

22 In (S2) = -1.51 + 2.16 [In (X)]

20 2

r = 0.914

18

n = 127

16

14 •

In (S2) 12

10 •

8 •

••••••

6

• f#I •

•••

4

2

0

0 2 4 6 8 10 12

In (X)

Figure 5. Plot of natural log variance vs. natural log mean for

weight of debris items per 100 square meters of beach

sampled. Data are from randomly located foreshore plots

only, sampled from June 1987 through September 1989.

46
80

70

60

50

40

30

20

10

o

Figure 6. Percentages, by marine debris category, of number and

weights of items per 100 square meters of beach sampled

in cleaned (c-beach) and uncleaned (u-beach) sampling

areas. Data are from randomly located foreshore plots

only, sampled from June 1987 through September 1989.

47

* u.s. GOVIORNMIONT PRINTING OFFICIO, 1991·557-335