ArticlePDF Available

Response of Coastal Fishes to the Gulf of Mexico Oil Disaster

PLOS
PLOS ONE
Authors:

Abstract and Figures

The ecosystem-level impacts of the Deepwater Horizon disaster have been largely unpredictable due to the unique setting and magnitude of this spill. We used a five-year (2006-2010) data set within the oil-affected region to explore acute consequences for early-stage survival of fish species inhabiting seagrass nursery habitat. Although many of these species spawned during spring-summer, and produced larvae vulnerable to oil-polluted water, overall and species-by-species catch rates were high in 2010 after the spill (1,989±220 fishes km-towed(-1) [μ ± 1SE]) relative to the previous four years (1,080±43 fishes km-towed(-1)). Also, several exploited species were characterized by notably higher juvenile catch rates during 2010 following large-scale fisheries closures in the northern Gulf, although overall statistical results for the effects of fishery closures on assemblage-wide CPUE data were ambiguous. We conclude that immediate, catastrophic losses of 2010 cohorts were largely avoided, and that no shifts in species composition occurred following the spill. The potential long-term impacts facing fishes as a result of chronic exposure and delayed, indirect effects now require attention.
Content may be subject to copyright.
Response of Coastal Fishes to the Gulf of Mexico Oil
Disaster
F. Joel Fodrie
1
*, Kenneth L. Heck Jr.
2
1 Institute of Marine Sciences and Department of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, North Carolina, United States of America,
2 Dauphin Island Sea Lab and Department of Marine Sciences, University of South Alabama, Dauphin Island, Alabama, United States of America
Abstract
The ecosystem-level impacts of the Deepwater Horizon disaster have been largely unpredictable due to the unique setting
and magnitude of this spill. We used a five-year (2006–2010) data set within the oil-affected region to explore acute
consequences for early-stage survival of fish species inhabiting seagrass nursery habitat. Although many of these species
spawned during spring-summer, and produced larvae vulnerable to oil-polluted water, overall and species-by-species catch
rates were high in 2010 after the spill (1,9896220 fishes km-towed
21
[m 6 1SE]) relative to the previous four years
(1,080643 fishes km-towed
21
). Also, several exploited species were characterized by notably higher juvenile catch rates
during 2010 following large-scale fisheries closures in the northern Gulf, although overall statistical results for the effects of
fishery closures on assemblage-wide CPUE data were ambiguous. We conclude that immediate, catastrophic losses of 2010
cohorts were largely avoided, and that no shifts in species composition occurred following the spill. The potential long-term
impacts facing fishes as a result of chronic exposure and delayed, indirect effects now require attention.
Citation: Fodrie FJ, Heck KL Jr (2011) Response of Coastal Fishes to the Gulf of Mexico Oil Disaster. PLoS ONE 6(7): e21609. doi:10.1371/journal.pone.0021609
Editor: Steven J. Bograd, National Oceanic and Atmospheric Administration/National Marine Fisheries Service/Southwest Fisheries Science Center, United States
of America
Received March 7, 2011; Accepted June 2, 2011; Published July 6, 2011
Copyright: ß 2011 Fodrie, Heck. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The authors acknowledge support from the National Marine Fisheries Service, National Oceanic and Atmospheric Administration Marine Fisheries
Initiative and Northern Gulf Institute. The funders had no role in study design, data collection and analyses, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: jfodrie @unc.edu
Introduction
Prevailing models of ecological impacts resulting from oil
pollution are being revised after the April 2010 release of ,4.4
million barrels [1] of oil into the northern Gulf of Mexico (GOM).
In part, this is a legacy of the Exxon Valdez accident as a
watershed environmental catastrophe, and the extensive research
on acute and chronic impacts of the resulting inshore oil pollution
[2]. Unlike the 0.25–0.5 million barrels released by the Valdez [2],
however, the Deepwater Horizon (DH) disaster hemorrhaged oil
into the open ocean at 1500 m depth over a protracted 84-day
period [1]. As a critical step toward new model development
applicable for detecting impacts of the DH spill, rigorous
observational data at organismal through community levels are
needed to guide ecosystem-based toxicology.
We have already learned that a significant fraction of the oil
released into the GOM from the Macondo well did not rise to the
surface, and this has implications for the ecosystem-level responses
we should anticipate. Rather, oil was emulsified at the well head
due to turbulent mixing, reduced buoyancy at depth, and addition
of Corexit 9500 dispersant. Subsequently, mid-water hydrocarbon
plumes [3] have been observed with stimulation of petroleum-
degrading bacteria [4]. With this now understood, we revisit some
early concerns regarding impacts for nearshore fisheries [5].
During the DH spill, near-surface waters lacked any reliable
refuge from oil pollution, as slicks/sheens occurred at the
immediate surface and oil was emulsified throughout the water
column. For many fishes, including commercially valuable
snappers (Lutjanidae) and groupers (Serranidae), spawning occurs
during the spring or summer (table S1), and eggs, larvae and post-
larvae would have relied upon near-surface waters overlaying the
continental shelf during the DH spill [6–7]. Furthermore, eggs/
larvae and oil can be transported by the same hydrodynamic and
atmospheric processes, enhancing the probability of oil encounters
for many species. Because the population ecology of marine
species with bipartite life histories is disproportionately affected by
the health and survival of early life stages [8], understanding how
eggs, larvae and newly-settled juveniles coped with the DH spill is
essential for quantifying ecosystem responses.
We hypothesized that the strength of juvenile cohorts spawned
on the northern GOM continental shelf during May–September
2010 in the northern GOM would be negatively affected by egg/
larval-oil interactions. Oiled seawater contains toxic compounds
such as polycyclic aromatic hydrocarbons (PAHs) which, even
after weathering, can result in genetic damage, physical deformi-
ties and altered developmental timing for fish eggs/larvae [9–10].
These effects may be induced at very low (,1 ppb PAHs) levels of
exposure when persistent over days to weeks [11–12] - timescales
relevant for larval development and descriptive of the DH spill.
Additionally, emulsified oil droplets could mechanically damage
the feeding and breathing apparatus of relatively fragile larvae and
further decrease individual fitness. Unfortunately, observing egg/
larval mortality, growth or migration in situ is an enduring
challenge for biological oceanographers, as eggs/larvae are simply
too dilute and experience relatively high instantaneous mortality,
even in undisturbed systems [13].
In the absence of direct observations on eggs and larvae,
juvenile abundance data provide valuable indices of the acute,
PLoS ONE | www.plosone.org 1 July 2011 | Volume 6 | Issue 7 | e21609
population-level responses of young fishes to the spill. Although
indirect evidence [14], early juvenile abundances are the
integrated products of early life-history processes such as
fertilization, larval growth/mortality, and settlement [6–8].
Therefore, effects of oil pollution on early life stages should be
detectable in time series data as shifts in the abundance of recently
settled juvenile fishes. We tested these predictions using 2006–
2010 survey data collected from the Chandeleur Islands, LA, to
Saint Joseph Bay, FL (Fig. 1), representing most of the nearshore
region directly impacted by oil. In contrast to the difficulties of
surveying marine larvae, quantitative measures of juvenile
abundances are tractable due to the tendency of settled fish to
aggregate in specialized nursery habitats [15]. In the northern
GOM, many fish species, such as those in the drum (Sciaenidae),
snapper and grouper families have juveniles that are routinely
collected from shallow-water seagrass meadows they use as
primary nurseries [16].
Our dataset consisted of 853 individual trawl samples taken
between July 15 and October 31 of 2006–2010 within seagrass
meadows of the northern GOM (tables S2, S3). We collected
167,740 individual fishes representing 86 taxa, and examined
catch-per-unit-effort (CPUE) data for all species pooled together,
as well as separately for each of the 20 most abundant species. We
also tested for post-spill community-level shifts in seagrass-
associated fish assemblages using multivariate analyses [17]. We
recognized that not all species were at equal risk for oil exposure
due to variation in spawning timing and larval distributions (tables
S1, S4). Furthermore, some species may have experienced release
from fishing pressure due to large-scale fishery closures [18] during
the spill (table S5), perhaps enhancing their larval production
during the summer spawning season. Therefore, we also
considered how these factors affected species-specific CPUEs
during 2010. In all analyses, comparisons among years were
considered as a proxy for the effects of oil disturbance (2006–2009
as undisturbed, 2010 as disturbed).
Results
Within the oil-affected GOM, a five-year survey of seagrass-
associated fish communities did not indicate reductions in juvenile
abundances following the spill. Rather, of the twenty most
commonly collected fish species, twelve were characterized by
statistically higher catch rates in 2010 relative to 2006–20009
(a = 0.05; Table 1). Among the remaining eight taxa, pre- and
post-spill catch rates were statistically indistinguishable. Across our
entire study region, CPUE increased from 1,080643 fishes km-
towed
21
(m 6 1SE) during 2006–2009 to 1,9896220 fishes km-
towed
21
in 2010. When resolved among four geographical areas
(Chandeleur Islands, Gulf Islands, Grand Bay, Florida Bays;
Fig. 1), overall catch rates of juvenile fishes, as well as CPUE of the
most abundant species, pinfish (Lagodon rhomboides), were consis-
tently higher during 2010 than in 2008 or 2009, and in some areas
were higher in 2010 than all previous years (Fig. 2A–B; fig. S1, S2,
S3; table S6).
The species composition of juvenile fish assemblages was
unaltered in each sampling area during the months following the
DH disaster (Fig. 3). Prior to the spill, similarities among individual
trawl samples (SIMPER) ranged from 50.3% at the Chandeleur
Islands to 52.9% within Florida Bays (table S7). By comparison,
similarity percentages between pre- (2006–2009) and post-spill
Figure 1. Sampling region and study sites. Map of juvenile fish sampling stations, divided among four survey areas: Chandeleur Islands (blue
circles), Gulf Islands (green circles), Grand Bay (orange circles) and Florida Bays (red circles). 1. Chandeleur Is., LA; 2. Ship Is., MS; 3. Horn Is., MS; 4. Petit
Bois Is., MS; 5. Dauphin Is., AL; 6. Grand Bature Shoal, AL; 7. Point Aux Pines, AL, 8. Big Lagoon, FL; 9. Pensacola Bay, FL; 10. Choctawhatchee Bay, FL;
11. St. Andrew Sound, FL; 12. St. Joseph Bay, FL. The spread of surface oil during the 84-day spill is also shown (brown shading). Image at lower right
shows juvenile gray snapper (L. griseus), spotted seatrout (C. nebulosus) and pipefish (Syngnathus spp.).
doi:10.1371/journal.pone.0021609.g001
Response of Fishes to GOM Oil Spill
PLoS ONE | www.plosone.org 2 July 2011 | Volume 6 | Issue 7 | e21609
(2010) samples were correspondingly high, ranging from 43.4%
within Grand Bay to 50.8% at the Chandeleur Islands.
Furthermore, pinfish, silver perch (Bairdiella chyrsoura), mojarras
(Eucinostomus spp.), pigfish (Orthopristis chrysoptera) and spotted
seatrout (Cynoscion nebulosus) drove similarity patterns both before
and after the spill (table S7). Species richness (S, up 15%,
p,0.001), diversity (ES
(20)
, up 11%, p = 0.006; H9, up 18%,
p,0.001) and evenness (J9, up 11%, p = 0.003) among trawl
samples were all slightly elevated during 2010 relative to 2006–
2009 averages (table S8; fig. S4), indicating that high CPUEs in
2010 were broad based.
When averaged across species, there was little statistical
evidence that either exposure risk or release from fishing pressure
significantly affected CPUEs during 2010. When comparing 2010
CPUE data against pre-spill catch rates, we did observe that fishes
characterized by moderate (spring spawning, nearshore larvae) or
high risk (spring-summer spawning, larvae distributed across the
continental shelf) exhibited decreases in CPUE following the spill
at the Chandeleur Islands and Grand Bay (Fig. 4A). However, no
statistically significant differences were found as a function of egg/
larval risk (F
4,848
= 1.4 10, p = 0.242) or sampling areas (F
3,849
= 0.999 ,
p = 0.440; table S9). Similarly, release from fishing pressure on
spawning fishes could be implicated, although not proven, as a
determinant of post-spill CPUEs. Along the Chandeleur and Gulf
Islands, increases in catch rates during 2010 relative to 2006–2009
were 800% and 950% higher, respectively (Fig. 4B), for species
identified in state and federal management plans than for species not
harvested by fishermen (table S5). No similar patterns were recorded
within Grand Bay or Florida Bays, however, and effects of fishing
pressure (F
1,851
=1.510, p = 0.223) and area (F
3,849
=1.397,
p = 0.225) on CPUE responses were not significant.
Discussion
Collectively, no significant, acute impacts on the strength of
juvenile cohorts within seagrass habitats were detected following
the DH disaster. This was true for all species examined, bolstering
our confidence in the conclusion that ecosystem-level injuries were
not severe for this community of fishes. Unfortunately, our
assessment cannot be compared to the most analogous spill, the
IXTOC 1 blowout [5], due to a paucity of formal scientific
investigation following that accident (The 1979 IXTOC I blowout
at 3600 m depth, 80-km north of the Yucata´n Peninsula, was a
,3.5-million-barrel spill.). The most parsimonious explanation for
our data is that these fishes were resilient to the spill, possibly due
to the retention of a large proportion of spilled oil at depth. As
such, these data add to a developing literature [3–4] in which the
acute impacts of the spill may be concentrated in the deep ocean
rather than shallow-water, coastal ecosystems that were the focus
of early concern [5]. For instance, gray snapper (Lutjanus griseus)
larvae were abundant in surface waters (0–25-m deep) over the
continental shelf from July through September [19], and were
among the most likely individuals to have contacted oil-polluted
water. Still, catch rates of gray snapper juveniles following the spill
Table 1. Relative frequencies and CPUE data for abundant fishes collected during sampling in seagrass meadows of the northern
GOM.
Scientific name
Cumlative %
Freq
2006–09
CPUE
2010
CPUE
P
(df = 851) Trend
Risk of oil
encounters
Potential release
from fishing
pressure
Lagodon rhomboides 60.22 644.86 1379.32 ,0.001
q
Moderate-Low No
Eucinostomus spp. 72.67 119.94 60.21 0.086 NC Low Potential Bycatch
Bairdiella chrysoura 82.66 123.10 163.77 0.117 NC Moderate-Low No
Orthopristis chrysoptera 89.90 80.31 118.73 0.007
q
Moderate Potential Bycatch
Lutjanus griseus 91.64 23.63 43.02 0.003
q
High Yes
Stephanolepis hispidus 93.29 11.95 70.61 ,0.001
q
High No
Lutjanus synagris 94.68 14.79 19.18 0.171 NC High Yes
Cynoscion nebulosus 95.74 13.41 36.51 ,0.001
q
Low Yes
Syngnathus spp. 96.63 11.57 20.05 0.057 NC Moderate-Low No
Chilomycterus schoepfi 97.46 7.37 18.56 ,0.001
q
Unknown No
Leiostomus xanthurus 97.78 4.63 2.56 0.533 NC Moderate-Low Potential Bycatch
Opsanus beta 98.04 2.73 6.63 ,0.001
q
Low No
Arius felis 98.29 2.62 10.14 0.021
q
Low Potential Bycatch
Nicholsina usta 98.52 2.11 6.86 0.003
q
Unknown No
Sphoeroides spp. 98.70 2.26 2.24 0.974 NC Low No
Blenniidae 98.86 2.06 5.27 0.002
q
Low No
Mycteroperca microlepis 99.01 1.96 1.75 0.773 NC High Yes
Paralichthys spp. 99.16 1.97 2.90 0.133 NC Moderate Yes/ Potential
Bycatch
Archosargus probatocephalus 99.31 1.58 5.95 ,0.001
q
Unknown Yes
Lactophrys quadricorn is 99.43 1.47 3.22 0.036
q
Unknown No
Trend symbols indicate no change (NC) or statistically significant increase (q) in catch rates during 2010 relative to 2006–2009. Risk of oil encounters determined by
spawning season and across-shelf larval distribution for each species. Potential release from fishing pressure guided by state and federal management plans, as well as
shrimp-trawl bycatch data (SI).
doi:10.1371/journal.pone.0021609.t001
Response of Fishes to GOM Oil Spill
PLoS ONE | www.plosone.org 3 July 2011 | Volume 6 | Issue 7 | e21609
were high relative to the four previous years (up 82%, Fig. 2C;
area * pre/post spill context interaction p,0.001, table S6).
When averaged across species - and in some cases across species
with vastly different life histories - there were no statistically
significant differences in the response of fished or unfished species
to the spill (or their responses to subsequent management actions;
i.e., fishery closures). Still, there were notable patterns suggesting
that certain species may have been released from harvest pressure
during 2010, subsequently enhancing spawning activity and post-
spill cohort sizes despite any potentially negative oil impacts. For
example, spotted seatrout spawn during summer [20], but many
mature individuals are typically removed by recreational fishers
before reproducing. Following the fishery closures in 2010, we
recorded order-of-magnitude higher juvenile abundances of
spotted seatrout at the Chandeleur and Gulf Islands, as well as
elevated catch rates throughout our survey region (Fig. 2D; area,
pre/post spill context and 2-way interaction p,0.001, table S6).
Consistent with the patterns observed in the species-by-species
catch data and analyses of ‘risk’’ or ‘fishing’’ effects, there were no
significant post-spill shifts in community composition and
structure, nor were there changes in any of several biodiversity
measures. While natural recruitment variability can make it
difficult to detect population-level impacts for any one species
following large-scale disturbance [14], our whole-community
analyses and results are likely robust against these concerns.
Several other factors could have contributed to the high catch
rates of seagrass-associated fishes in 2010 despite large-scale oil
pollution. For instance, fishes may be uniquely buffered against oil
pollution due to their mobility or foraging ecology [21–22]. Also,
the major predators of fish eggs/larvae (e.g., gelatinous zooplank-
ton) may have been impacted by the spill, thereby reducing
natural mortality rates for coastal fishes [23]. Regardless of the
mechanism(s) involved, thus far the potential for 2010 cohorts to
support regional fisheries over the next several years has persisted
despite the spill. This information is critical for projecting the
mode and tempo of ecological and economic recovery in the oil-
affected GOM, as well as guiding future conservation/restoration
activities to mitigate oil-spill injuries.
While these data provide reason for early optimism, attention
should now turn to possible chronic effects of oil exposure on fishes
as well as delayed indirect effects cascading through the post-spill
GOM. Fish may suffer growth, survival or reproductive penalties
years after exposure to oil [24], or experience altered migratory
behaviors [25]. Oil sequestered in sediments may also affect
species laying benthic eggs for several years [26]. More broadly,
ecosystems experiencing large-scale disturbance can carry or build
Figure 2. Catch rates of juvenile fishes, 2006–2010. Catch rates among years and sampling areas (Chandeleur Islands, Gulf Islands, Grand Bay
and Florida Bays) for: (A) all fishes pooled; (B) pinfish (L. rhomboides), (C) gray snapper (L. griseus), and (D) spotted seatrout (C. nebulosus). CPUE data in
panels B–D are presented on a log scale, and all data are shown as means of trawl samples (m + 1SE).
doi:10.1371/journal.pone.0021609.g002
Response of Fishes to GOM Oil Spill
PLoS ONE | www.plosone.org 4 July 2011 | Volume 6 | Issue 7 | e21609
instabilities over protracted periods that can eventually result in
delayed collapses of fisheries stocks [27].
Improved threat assessment for energy exploration [28] and
process-oriented studies of ecosystem responses will be long-term
initiatives resulting from the DH spill. In the short term, however,
observational data collected over relevant spatial and temporal
scales are invaluable for guiding and evaluating targeted studies of
oil toxicology [29]. For fish species experiencing multiple stressors
such as habitat degradation [30] harvest pressure [31], climate
change [16], and now oil pollution, rigorous baseline survey data
and new syntheses are needed to enact effective ecosystem-based
management.
Materials and Methods
Sampling
We analyzed changes in northern Gulf of Mexico (GOM)
seagrass-associated fish communities during the last 5 years by
comparing survey data obtained either prior to (2006–2009) or
immediately following the Deepwater Horizon disaster (2010).
The survey region extended approximately 340 km along the
coastline, including a significant portion of the inshore area most
affected by oil (Fig. 1.). Each year, we made repeated sampling
trips to 12 sites, extending from the Chandeleur Islands, LA, to St.
Joseph Bay, FL (29.68–30.72uN, 85.30–89.10uW). Sampling
occurred within mixed seagrass meadows that serve as primary
nursery habitat for many juvenile fishes that have recently settled
from the water column following a 5–45 day larval period [6,16].
Our samples were collected from seagrass mosaics that included
turtle grass (Thalassia testudinum), shoal grass (Halodule wrightii),
widgeon grass (Ruppia maritima), and manatee grass (Syringodium
filiforme), along with scattered unvegetated patches (table S3).
During each year, trawls were conducted from July 15 through
October 31 in order to record the abundances and composition of
fishes during the period when seagrass meadows are utilized as
primary nurseries by recently settled juveniles (refer to table S1 for
reproductive seasons of common fishes). Fishes were collected
using a 5-m otter trawl (2.0-cm body mesh; 0.6-cm bag mesh;
0.360.7-m doors) with conventional 4-seam balloon design
including float and lead lines but without tickler chains. Trawls
consisted of 3.960.1 (m 6 1SE) minute tows behind small (,7m)
research vessels traveling at 3.3+0.1 kilometers hour
21
. Overall,
853 samples were taken (table S2), and the trawl covered a linear
distance of 184.7 kilometers during our sampling. These trawls
occurred in depths of 0.5–2.5-m, and were conducted during
daylight hours. During our surveys, species were enumerated in
the field unless species-level identifications were not easily made.
Unidentified specimens were transported to the lab where
meristics were used by at least two different technicians to identify
each individual. In cases in which species could not be identified,
specimens were classified to the lowest taxonomic level possible.
Typically, fishes were 20–100 mm long (standard length),
indicative of recently-spawned juveniles. However, we did not
record individual sizes for all species, and, for pipefishes (Syngnathus
Figure 3. Community composition of seagrass-associated fish communities, 2006–2010. Multi-dimensional scaling plots for seagrass-
associated fish communities prior to (2006–2009; colored symbols) and following (2010; black circles) the DH spill. Data for (A) Chandeleur Islands, (B)
Gulf Islands, (C) Grand Bay and (D) Florida Bays are presented separately. Each datum represents a single trawl sample.
doi:10.1371/journal.pone.0021609.g003
Response of Fishes to GOM Oil Spill
PLoS ONE | www.plosone.org 5 July 2011 | Volume 6 | Issue 7 | e21609
spp.) and hard-headed catfish (Arius felis), we did observe that a
small proportion of our catch included reproductive adults. For
four species: gray snapper (50.560.8 mm [m 6 SE]), lane snapper
(Lutjanus synagris; 55.760.7 mm), spotted seatrout (60.861.1 mm)
and gag grouper (Mycteroperca microlepis; 157.563.2 mm); we did
record the sizes of all individuals throughout our surveys. Based on
our own otolith analyses (Fodrie unpublished) and published
reports of first-year growth among these four species (age-1 sizes:
gray snapper ,109 mm; lane snapper ,140 mm; spotted seatrout
,127 mm; gag grouper .198 mm), we calculated that .96% of
individuals were captured in the same year as they were spawned
(including 2010).
Once enumerated, fishes were entered in to an Excel database,
and abundance data were converted into catch-per-unit-effort
(CPUE) data based on the linear distance over with each trawl
occurred. All statistical analyses were applied to these CPUE data.
Our complete CPUE dataset is included as a separate appendix in
our supporting information (dataset S1). This study was carried
out in strict accordance with the recommendations in the Guide
for the Care and Use of Laboratory Animals of the National
Institutes of Health. Our sampling protocol was approved by the
Committee on the Ethics of Animal Experiments of the University
of North Carolina at Chapel Hill (Permit Number: 10-114.0).
Statistical analyses
We investigated differences in the catch rates of seagrass-
associated fishes (all species pooled as well as the 20 most abundant
species individually) by unpaired t-tests comparing pre- (2006–2010)
and post-spill (2010) data (Table 1), as well as 2-way ANOVAs in
which sampling area (Chandeleur Islands, Gulf Islands, Grand Bay,
Florida Bays) and context (pre- versus post-spill) were fixed factors
(table S6). Regions were defined by basic geomorphology and
location, local water clarity, local salinity, and local seagrass
composition [32]. Because variances were stable among groups,
no data transformations were required prior to analyses.
We analyzed similarities and differences in fish communities
among years (2006–2009 versus 2010) within each sampling area
(each area considered separately) using non-metric multidimen-
sional scaling (MDS), based on Bray-Curtis similarity indices
among all individual trawl samples (4
th
root-transformed data).
Pairwise comparisons between trawl samples across years were
conducted with analysis of similarity (ANOSIM) and similarity (or
dissimilarity) percentages (SIMPER) using PRIMER 5.2.2 soft-
ware (PRIMER-E Ltd; [33]).
We also examined patterns of species diversity among regions
and years by computing the following measures for each trawl
sample: S, number of species collected; ES
(20)
, species richness
rarefied to 20 individuals; H9, Shannon-Weiner diversity index
(log
e
); and J9, Pielou’s evenness measure (PRIMER 5.2.2 software).
We investigated differences in community diversity via 2-way
ANOVAs in which sampling area (Chandeleur Islands, Gulf
Islands, Grand Bay, Florida Bays) and context (pre- versus post-
spill) were fixed factors. Because variances were stable among
groups, no data transformations were required prior to analyses.
Figure 4. Larval risk and fishery closure impacts. Effects of (A) egg/larval vulnerability and (B) harvest pressure on the responses of fishes to the
DH spill. Response of individual species calculated as the ratio of 2010 versus 2006–2009 CPUE data. Data are presented on a log scale as group
means (m + 1SE), with ratios .1 indicating that 2010 catch rates were elevated relative to 2006–2010 data.
doi:10.1371/journal.pone.0021609.g004
Response of Fishes to GOM Oil Spill
PLoS ONE | www.plosone.org 6 July 2011 | Volume 6 | Issue 7 | e21609
These approaches are proscribed in earlier syntheses for
detecting environmental impacts [17]. Critiques of employing
parametric testing to detect ecosystem injury exist due to
interannual variability and reduced statistical power [14], although
those concerns have focused on analyses involving single species.
We determined the relative probability for oil-larvae encounters
(‘risk’) for the twenty most commonly captured fishes, and used
these data to explore how individual species responded differently to
large-scale oil pollution in the northern GOM. Information on the
seasonal timing of spawning and distribution of larvae from shore to
the outer margin of the continental shelf was collected from the
literature (tables S1 and S4), and used to define 4 levels of risk (in
addition to an ‘unknown’ [n = 4] category containing species for
which no data were available). ‘Low’ risk species (n = 6) included
those in which larvae remained inside estuaries, either in the
plankton or as benthic egg masses, regardless of spawning season.
‘Moderate-Low’ risk species (n = 4) were defined by having either 1)
larvae distributed in estuaries as well as across the continental shelf,
or 2) larvae distributed across the continental shelf, but not likely
during the spill period (i.e., April–September). Only two ‘Moderate’
risk species were identified: pigfish (Orthopristis chrysoptera) spawn
throughout summer, and have larvae distributed within nearshore
waters; while flounder (Paralichthys spp.) have larvae distributed
across the continental shelf, with a protracted spawning that extends
into April or May (i.e., some overlap with the oil spill). ‘High’ risk
species (n = 4) spawn offshore and have larvae distributed across the
continental shelf. Furthermore, spawning data indicates that these
species would have produced larvae sometime during the DH spill
(April–Sept in our classification scheme). Based on these risk guilds,
we examined the response of fishes to the spill by calculating the
ratio of 2010 CPUE data (averaged) to 2006–2009 CPUE data
(averaged) for each species. Following these calculations, ratios .1
indicate that average 2010 catch rates were higher than during the
previous 4 years, while ratios ,1 indicate that average 2010 catch
rates were lower than during the previous 4 years. Using each
species as a replicate measure, we used ‘risk’ and region
(Chandeleur Islands, Gulf Islands, Grand Bay, Florida Bays) as
fixed factors in a 2-way ANOVA that compared 2010 CPUE:
2006–2009 CPUE trends. Because variances were stable among
groups, no data transformations were required prior to analyses.
Similarly, we determined whether species were likely to have
experienced significant release from harvest pressure following
large-scale closures in the northern GOM, and examined how this
may have affected CPUE data in 2010. For each of the twenty
most commonly caught fish, we designated species as ‘fished’ if
they were included in any state or federal management plan as of
Dec 31, 2010 (table S5), or identified as ,1% (by biomass) of
bycatch in shrimp trawl fisheries within the northern GOM (table
S5). As before, we examined the response of fishes to the spill by
calculating the ratio of 2010 CPUE data (averaged) to 2006–2009
CPUE data (averaged) for each species. Using each species as a
replicate measure, we used ‘fishing pressure’ (with fished species
including species that are targeted or captured as incidental
bycatch at significant levels) and region (Chandeleur Islands, Gulf
Islands, Grand Bay, Florida Bays) as fixed factors in a 2-way
ANOVA that compared 2010 CPUE: 2006–2009 CPUE trends.
Because variances were stable among groups, no data transfor-
mations were required prior to analyses.
All univariate tests were conducted using StatView 5.0.1 software
(SAS Institute Inc.). Because each statistical analysis applied to
separate and easily distinguishable hypotheses, we made no
corrections to experiment-wise alpha for any of the univariate (total
fishes CPUE, individual fishes CPUE, risk guilds, harvest guilds,
diversity) or multivariate (ANOSIM) tests we conducted [34].
Supporting Information
Figure S1 Catch rates of all fishes, pooled together, among
sampling areas prior to (2006–2009) and following (2010) the
Deepwater Horizon disaster.
(DOCX)
Figure S2 Catch rates of individual species, among sampling
areas prior to (2006–2009) and following (2010) the Deepwater
Horizon disaster. Data are presented for the 20 most abundant
species.
(DOCX)
Figure S3 Catch rates among sampling areas and years for the
20 most abundant species collected during trawl surveys.
(DOCX)
Figure S4 Diversity measures for seagrass-associated fish
communities within sampling areas affected by the Deepwater
Horizon disaster.
(DOCX)
Table S1 Summary table for CPUE data (fish kilometer-
towed
21
) of fishes prior to (2006–2009) and following (2010) the
DH disaster.
(DOCX)
Table S2 Distribution of trawl samples among sampling areas
(Chandeleur Islands, Gulf Islands, Grand Bay, Florida Bays) and
years (2006–2010).
(DOCX)
Table S3 Quantitative description of seagrass habitats sampled
throughout the northern Gulf of Mexico during 2006–2010.
(DOCX)
Table S4 Information used to determine the likelihood of larvae
contacting oiled water during the summer of 2010.
(DOCX)
Table S5 Summary table for the management status of the 20
most abundant fishes collected during our survey program.
(DOCX)
Table S6 Summary table of the effects of sampling area and
year (context: pre- versus post-spill) on the catch rates of the 20
most abundant fishes collected during surveys in northern Gulf of
Mexico seagrass meadows.
(DOCX)
Table S7 Comparisons of community structure between catch
data prior to (2006–2009) or immediately following (2010) the
Deepwater Horizon disaster (ANOSIM and SIMPER).
(DOCX)
Table S8 Summary table of the effects of sampling area and
year (context: pre- versus post-spill) on the diversity (S, ES
(20)
,H9,
and J9) of trawl samples collected within northern Gulf of Mexico
seagrass meadows.
(DOCX)
Table S9 Summary table of the effects of sampling area, larval
risk and harvest pressure on the change in catch rates of individual
species for pre- (2006–2009) and post-spill (2010) data.
(DOCX)
Dataset S1 Complete CPUE data obtained for 2006–2009 trawl
surveys within seagrass meadows of the northern Gulf of Mexico.
(XLSX)
Response of Fishes to GOM Oil Spill
PLoS ONE | www.plosone.org 7 July 2011 | Volume 6 | Issue 7 | e21609
Acknowledgments
We are extremely grateful to the students and technicians who aided in the
field, especially C. Baillie, M. Brodeur, J. Myers, O. Rhoades and S.
Williams. B. Raines supplied the image of juvenile fishes in Fig. 1.
Constructive comments and support were provided by S. Powers, C.
Peterson, J. Kenworthy, and 2 anonymous reviewers.
Author Contributions
Conceived and designed the experiments: FJF KLH. Performed the
experiments: FJF KLH. Analyzed the data: FJF. Wrote the paper: FJF
KLH.
References
1. Crone TJ, Tolstoy M (2010) Magnitude of the 2010 Gulf of Mexico Oil Leak.
Science 330: 634–643.
2. Peterson CH, Rice SD, Short JW, Esler D, Bodkin JL, et al. (2003) Long-term
ecosystem response to the Exxon Valdez Oil Spill. Science 302: 2082–2086.
3. Camilli R, Reddy CM, Yoerger DR, Van Mooy BAS, Jukuba MV, et al. (2010)
Tracking hydrocarbon plume transport and biodegradation at Deepwater
Horizon. Science 330: 201–204.
4. Hanzen TC, Dubinsky EA, DeSantic TZ, Andersen GL, Piceno YM, et al.
(2010) Deep-sea oil plume enriches indigenous oil-degrading bacteria. Science
330: 204–208.
5. Kerr R, Kintisch E, Stokstad E (2010) Will Deepwater Horizon set a new
standard for catastrophe? Science 328: 674–675.
6. Able KW, Fahay MP Ecology of Estuarine Fishes, Temperate Waters of the
Western North Atlantic (The Johns Hopkins University Press). 566 p.
7. Miller BS, Kendall AW Early Life History of Marine Fishes (University of
California Press). 376 p.
8. Hjort J (1914) Fluctuation in the great fisheries of northern Europe reviewed in
the light of biological research. Rappo rts et Proce`s-Verbaux des Re´unions du
Conseil International pour l’Exploration de la Mer 20: 1–228.
9. Kocan RM, Hose JE, Brown ED, Baker TT (1996) Injury to the early life history
stages of Pacific herring in Prince William Sound after the Exxon Valdez oil spill.
Can J Fish Aquat Sci 53: 2366–2375.
10. Tuvikene A (1995) Responses of fish to polycyclic aromatic hydrocarbons
(PAHs). Ann Zool Fennici 32: 295–309.
11. Carls MG, Rice SD, Hose JE (1999) Sensitivity of fish embryos to weathered
crude oil: Part I. Low-level exposure during incubation causes malformations,
genetic damage, and mortality in larval pacific herring (Clupea pallasi). Environ
Toxicol Chem 18: 481–493.
12. Brown ED, Baker TT, Hose JW, Kocan RM, Marty GD, et al. (1996) Injury to
the early life history stages of Pacific herring in Prince William Sound after the
Exxon Valdez oil spill. Am Fish Soc Sym 18: 448–462.
13. Levin LA (2006) Recent progress in understanding larval dispersal: new
directions and digressions. Integr Comp Biol 46: 282–297.
14. Hilborn R (1996) Detecting population impacts from oil spills: a comparison of
methodologies. Am Fish Soc Sym 18: 639–644.
15. Beck MW, Heck KL, Able KW, Childers DL, Eggleston DB, et al. (2001) The
identification, conservation, and management of estuarine and marine nurseries
for fish and invertebrates. Bioscience 51: 633–641.
16. Fodrie FJ, Heck KL, Powers SP, Graham WM, Robinson KL (2010) Climate-
related, decadal-scale assemblage changes of seagrass-associated fishes in the
northern Gulf of Mexico. Glob Change Biol 16: 48–59.
17. Underwood AJ in Detecting Ecological Impacts: Concepts and Applications in
Coastal Habitats, Schmitt RJ, Osenberg CW (Academic Press). pp 151–175.
18. NOAA Fisheries Service Deepwater Horizon Oil Spill Information. Available:
http://sero.nm fs.noaa.go v/deepwater_hor izon_oil_spill.htm. Accessed: 2011
Jun 13.
19. D’Alessandro EK, Sponaugle S, Serafy JE (2010) Larval ecology of a suite of
snappers (family: Lutjanidae) in the Straits of Florida, west ern Atlantic Ocean.
Mar Ecol Prog Ser 410: 159–175.
20. Holt GJ, Holt SA (2000) Vertical distribution and the role of physical processes
in the feeding dynamics of two larval sciaenids Sciaenops ocellatus and Cynoscion
nebulosus. Mar Ecol Prog Ser 193: 181–190.
21. Peterson CH, Kennicutt MC, Green RH, Montagna P, Harper DE, et al. (1996)
Ecological consequences of environmental perturbations associated with offshore
hydrocarbon production: a perspective on long-term exposures in the Gulf of
Mexico. Can J Fish Aquat Sci 53: 2637–2654.
22. Edgar GJ, Marshall PA, Mooney P (2003) The effect of the Jessica grounding on
Gala´pagos reef fish communities adjacent to the wreck site. Mar Pollut Bul 47:
296–302.
23. Graham WM, Condon RH, Carmichael RH, D’Ambra I, Patterson HK, et al.
(2010) Oil carbon entered the coastal planktonic food web during the Deepwater
Horizon oil spill. Environ Res Lett 5: 045301.
24. Heintz RA, Rice SD, Wertheimer AC, Bradshaw RF, Thrower FP, et al. (2000)
Delayed effects on growth and marine survival of pink salmon Oncorhynchus
gorbuscha after exposure to crude oil during embryonic development. Mar Ecol
Prog Ser 208: 205–216.
25. Wertheimer AC, Heintz RA, Thedinga JF, Maselko JM, Rice SD (2000)
Straying behavior of adult pink salmon (Oncorhynchus gorbuscha) exposed as
embryos to weathered Exxon Valdez crude oil. Trans Am Fish Soc 129:
989–1004.
26. Bue BG, Sharr S, Seeb JE (1998) Evidence of damage to pink salmon
populations inhabiting Prince William Sound, Alaska, two generations after the
Exxon Valdez Oil Spill. Trans Am Fish Soc 127: 35–43.
27. Pearson WH, Elston RA, Bienert RW, Drum AS, Antrim LD (1999) Why did
the Prince William Sound, Alaska, Pacific herring (Clupea pallasi) fisheries collapse
in 1993 and 1994. Can J Fish Aquat Sci 56: 711–737.
28. U. S. Department of the Interior, Minerals Management Service Environmental
Division, ‘‘Oil-Spill Risk Analysis: Gulf of Mexico Outer Continental Shelf
(OCS) Lease Sales, Eastern Planning Area, 2003–2007 and Gulfwide OCS
Program, 2003–2042’’ OCS Report MMS 2002–069.
29. Sagarin R, Pauchard A (2010) Observational approaches in ecology open new
ground in a changing world. Front Ecol Environ 8: 379–386.
30. Diaz RJ, Rosenberg R (2008) Spreading dead zones and consequences for
marine ecosystems. Science 321: 926–929.
31. Baum JK, Myers RA (2004) Shifting baselines and the decline of pelagic sharks
in the Gulf of Mexico. Ecol Lett 7: 135–145.
32. Byron D, Heck KL (2006) Hurricane effects on seagrasses along Alabama’s Gulf
Coast. Estuar Coast 29: 939–942.
33. Clark KR, Gorley RN (2001) PRIMER v5: User Manual/Tutorial. Plymouth:
Plymouth Marine L aboratory.
34. Moran MD (2003) Arguments for rejecting the sequential Bonferroni in
ecological studies. Oikos 100: 403–405.
Response of Fishes to GOM Oil Spill
PLoS ONE | www.plosone.org 8 July 2011 | Volume 6 | Issue 7 | e21609
... This Communicated by Joel Trexler. is particularly true of marine systems, which are heavily impacted by anthropogenic activities such as nutrient loading, pollution, and overfishing (Darimont et al. 2015;Worm 2015). Therefore, perturbations that disrupt human activities in coastal ecosystems may have particularly notable outcomes (Fodrie and Heck 2011). Specifically, fishing pressure and predator removal have substantial consequences for community structure and function (Hughes 1994;Pauly et al. 1998;Myers and Worm 2003). ...
... Fishing disruptions benefit marine species and allow their abundance to increase (Fodrie and Heck 2011;Narimatsu et al. 2017). After the Deepwater Horizon Oil Spill in the Gulf of Mexico in 2010 and the 2011 Fukushima nuclear disaster in Japan, fish populations increased when fishing was restricted (Fodrie and Heck 2011;Narimatsu et al. 2017). ...
... Fishing disruptions benefit marine species and allow their abundance to increase (Fodrie and Heck 2011;Narimatsu et al. 2017). After the Deepwater Horizon Oil Spill in the Gulf of Mexico in 2010 and the 2011 Fukushima nuclear disaster in Japan, fish populations increased when fishing was restricted (Fodrie and Heck 2011;Narimatsu et al. 2017). Disturbances, such as hurricanes, may similarly reduce fishing pressure by damaging fishing infrastructure (piers, docks, bait shops; Supplemental Figure 1) and boats as well as reducing coastal access, tourism, and amenities (Smee et al. 2020). ...
Article
Full-text available
Intense disturbances such as hurricanes may drastically affect ecosystems, producing both acute and long-term changes along coastlines. By disrupting human activities (e.g., fishing), hurricanes can provide an opportunity to quantify the effects of these activities on coastal ecosystems. We performed predator-exclusion experiments on oyster reefs in 2016, one-year before a category-4 hurricane (“Harvey”) and again in 2018 one-year post-hurricane where the storm made landfall. Additionally, we examined 8 years (2011–2018) of fisheries-independent data to gauge how fishing pressure and fish populations were affected by the storm in three locations that varied in storm impacts. In the month following Hurricane Harvey, fishing effort dropped by 90% in the area with wind and flooding damage, and predatory fish species commonly targeted by anglers were 300% more abundant than the year prior to the hurricane. The locations without damage to fishing infrastructure did not experience declines in fishing pressure or changes in fish abundance, regardless of flooding disturbance. Reef fish and invertebrate communities directly affected by the storm were significantly different after the hurricane and were ~ 30% more diverse. With low fishing pressure, sportfish CPUE were 1.7–6.9 × higher immediately after the hurricane. Intermediate consumers, such as crabs that prey on oysters, were 45% less abundant and 10% smaller. These results indicate that hurricanes can temporarily disrupt human-ecosystem linkages and reconstitute top-down control by sportfish in estuarine food webs. Disturbance events that interrupt or weaken those interactions may yield indirect ecological benefits and provide insights into the effects of human activities on food webs.
... Natural disasters, e.g., hurricanes and storms, pose intricate management challenges to governmental agencies (Adger et al., 2005;Game et al., 2008;Cetin et al., 2024). Understanding the successional dynamics of ecological communities after such events is critical to inform management interventions that promote ecosystem recovery, such as the placement of temporary closed areas where human extractive activities are prohibited (Fodrie and Heck, 2011;Smee et al., 2020). Volcanic eruptions can have devastating consequences for marine communities and the livelihood of human societies that depend upon them (Crisafulli et al., 2015, Global Volcanisms Program, 2023. ...
... These subtropical seagrass communities are frequently characterized by very high abundances of pinfish Lagodon rhomboides. In North Carolina and areas south through Florida and into the Gulf of Mexico, pinfish are the most dominant members of the nearshore fish community and are often associated with structured habitats, such as seagrasses (Adams 1976b, Fodrie & Heck 2011, Faletti et al. 2019. These mesopredators are a key link in the food web, transferring energy and nutrients acquired from foraging in seagrass meadows (and other nearshore benthic habitats) to higher predators and along the coast in quantities unparalleled by other organisms (Nelson et al. 2013). ...
Article
Full-text available
As climate change continues to shift the distributions of species worldwide, understanding where, why, and how organisms move beyond their historical ranges is of critical importance. Here, we report on the expansion of pinfish Lagodon rhomboides poleward along the mid-western Atlantic in response to rising temperatures. Pinfish are a key interactor in nearshore subtidal habitats like seagrasses in the southwestern Atlantic and Gulf of Mexico, but they have been historically sparse north of the ecotone at Cape Hatteras, North Carolina, USA. Using multi-decadal trawl surveys, we show that while pinfish have been present both below (North Carolina) and above (Virginia and Maryland) this ecotone for many years, they have increasingly intruded into restored eelgrass ( Zostera marina ) meadows in the coastal bays of Virginia over the past decade. In 2022, for instance, pinfish abundances in Virginia equaled those observed historically in North Carolina. To understand the factors promoting these changes in abundance, we used a passive drifter model to show that these increases are not necessarily tied to changes in offshore currents. Instead, linear models revealed that the local abundance of pinfish in Virginia correlates most with inshore summertime water temperatures. Thus, favorable environmental conditions of the recipient bays appear to encourage greater recruitment and therefore greater abundance of pinfish. Given their outsized ecological role in subtropical ecosystems, and that the climate will continue to warm, our findings suggest that pinfish may soon come to dominate the structure and functioning of temperate seagrass meadows in Virginia and beyond.
... The Gulf of Mexico (GoM) is ecologically productive and economically important, providing the nation critical ecosystem services (Fodrie and Heck Jr, 2011) and lucrative fisheries (Adams et al., 2004;Liu et al., 2017a). Physically, the GoM is highly dynamic and primarily driven by a variety of hydrographic processes. ...
Article
Full-text available
Dynamic influences of ocean processes on distribution, abundance, and diversity of zooplankton communities were studied over the continental shelf in the northern Gulf of Mexico (GoM) from 2015 to 2017. Zooplankton sampling was conducted on four summer cruises in the northcentral GoM. Sampling was designed in waters potentially influenced by the Loop Current (LC) and/or Mississippi River discharge to assess the impacts of these two mesoscale features on the abundance and diversity of zooplankton. During the three-year study, the LC displayed distinct spatial-temporal variations in penetration and occurrence in the northern GoM. Environmental conditions (i.e., sea surface temperature, salinity, and dissolved oxygen) varied between months and years sampled, and were significantly different among cruises (ANOVA, p < 0.001). The majority of zooplankton consisted of calanoid copepods (65% ± 7.2%, mean ± SD), while non-copepod taxa were primarily chaetognaths, polychaetes, tunicates, and ostracods (23 ± 9.2%). Species abundance and diversity of zooplankton were significantly correlated with sea surface temperature, salinity, and dissolved oxygen (p < 0.05). Canonical correspondence analysis displayed significant associations between mesoscale features and dominant zooplankton groups among cruises and by taxa (Monte Carlo Permutation Test, p < 0.001). In addition, nonmetric multidimensional scaling indicated that zooplankton assemblages were distinct, likely caused by Mississippi River plumes during the study period. As one of the few efforts to examine zooplankton dynamics at a low taxon level over the GoM continental shelf regarding the impact of mesoscale features, this study revealed seasonal (i.e. summer) and spatial patterns in distribution, abundance, and diversity of zooplankton communities subjected to the dynamic physicochemical conditions in the northern GoM, which will continue in a changing climate.
... They can infiltrate intertidal zones, living habitats such as mussel beds (Carls et al. 2001), and upstream into freshwater habitats . Impacts from oil spills linger, continually affecting EFH for decades (Hayes and Michel 1999, Carls et al. 2004, Iverson and Esler 2010, Fodrie and Heck 2011, McCall and Pennings 2012. ...
Technical Report
Full-text available
Provides conservation recommendations to state and federal agencies planning actions that may adversely affect EFH.
... Diverse estuarine assemblages (e.g., microbes, plants, macroinvertebrates, and fishes) tend to be tolerant of severe environmental stress (Elliott & Whitfield, 2011;Stevens, 1989), such as oil spills (Able et al., 2015;Engel et al., 2017;Fleeger et al., 2020;Fodrie et al., 2014;Fodrie & Heck, 2011;McCann et al., 2017;Zengel et al., 2022) and hurricanes (Chen et al., 2020), although there can also be high and fast turnover of species and diversity in estuaries due to salinity gradients (Elliott & Whitfield, 2011;Watson & Byrne, 2009;Whitfield et al., 2012). Both LHA and LHB were located near Lake Hermitage and the Mississippi River, a region with lower salinity levels that experiences weaker storms coming from Barataria Bay and the Gulf of Mexico compared with other marshes. ...
Article
Full-text available
Coastal wetlands are rapidly disappearing worldwide due to a variety of processes , including climate change and flood control. The rate of loss in the Mississippi River Delta is among the highest in the world and billions of dollars have been allocated to build and restore coastal wetlands. A key question guiding assessment is whether created coastal salt marshes have similar biodiversity to preexisting, reference marshes. However, the numerous biodiversity metrics used to make these determinations are typically scale dependent and often conflicting. Here, we applied ecological theory to compare the diversity of different assemblages (surface and below-surface soil microbes, plants, macroinfauna, spiders, and on-marsh and off-marsh nekton) between two created marshes (4-6 years old) and four reference marshes. We also quantified the scale-dependent effects of species abundance distribution, aggregation, and density on richness differences and explored differences in species composition. Total, between-sample, and within-sample diversity (γ, β, and α, respectively) were not consistently lower at created marshes. Richness decomposition varied greatly among assemblages and marshes (e.g., soil microbes showed high equitability and α diversity, but plant diversity was restricted to a few dominant species with high aggregation). However, species abundance distribution, aggregation, and density patterns were not directly associated with differences between created and reference marshes. One exception was considerably lower density for macroinfauna at one of the created marshes, which was drier because of being at a higher elevation and having coarser †
Preprint
Full-text available
Crude oil can affect the normal eye development and swimming behavior of fish embryos. In this study 0-4 hours post fertilization (hpf) zebrafish (Danio rerio) embryos were exposed to low, sublethal concentrations of water-accommodated fractions (WAF) of a naphthenic North Sea crude oil alone and in combination with a third-generation chemical dispersant. Effects on eye development and function at the transcript, histological, morphological, and behavioral level were assessed relative to untreated control specimen at 119 hpf. Exposed embryos swam significantly less during the dark phases of the light/dark transition test. Eye size of zebrafish embryos was significantly smaller in groups exposed to crude oil WAFs. Zebrafish retina histology revealed that, among other structural alterations, the outer nuclear layer, containing photoreceptor cells relevant for normal visual functioning, was significantly thinner in exposed embryos. Transcriptome analysis revealed that several genes involved in eye development and function (opsins and crystallins) were dysregulated upon oil exposure. The molecular effects on gene expression and eye histology results form a novel line of evidence that explains the observed effects of crude oil on the swimming activity of exposed fish embryos. The present study is in line with recent findings highlighting the importance of ocular toxicity in developing embryos exposed to petroleum samples at environmentally relevant and non-lethal concentrations without visible malformations. The study suggests that oculotoxicity should be considered as a major toxicity pathway alongside to the well-established cardiotoxicity.
Article
Full-text available
There is an increased interest in porous materials due to their unique properties such as high surface area, enhanced catalytic properties, and biological applications. Various solvent-based approaches have been already used to synthesize porous materials. However, the use of large volume of solvents, their toxicity, and time-consuming synthesis make this process less effective, at least in terms of principles of green chemistry. Mechanochemical synthesis is one of the effective eco-friendly alternatives to the conventional synthesis. It adopts the efficient mixing of reactants using ball milling without or with a very small volume of solvents, gives smaller size nanoparticles (NPs) and larger surface area, and facilitates their functionalization, which is highly beneficial for antimicrobial applications. A large variety of nanomaterials for different applications have already been synthesized by this method. This review emphasizes the comparison between the solvent-based and mechanochemical methods for the synthesis of mainly inorganic NPs for potential antimicrobial applications, although some metal-organic framework NPs are briefly presented too.
Article
Full-text available
After the explosion and subsequent sinking of the Deepwater Horizon (DWH) on 22 April 2010, an estimated 780,000 m3 of Sweet Louisiana Crude (SLC) and 205,000 mT of methane were released into the northern Gulf of Mexico over an 85 d period. A great deal of controversy ensued regarding the application of unprecedented volumes of chemical dispersants both at the surface and at depth. One of the consequences of dispersing such large volumes of oil into the water column was the difficulty of tracking its fate over distance and through the food web. Most of the attention to date has been on large underwater plumes of oil, and scant evidence exists for subsea oil in warm (>25 °C), shallow shelf waters due to rapid weathering and utilization by prokaryotes. A large pool of isotopically depleted carbon from released oil and methane is presumably available to zooplankton and zooplankton-eating fish and invertebrates via prokaryotic consumers. Thus, carbon isotopic depletion extending into marine zooplankton grazers, a pathway mediated by the microbial food web, is a good proxy for food web modification by the spill. We employed delta13C as a tracer of oil-derived carbon incorporation into the lower marine food web across the middle and inner continental shelf. During June-August 2010, we followed two particle size classes: the nominally 1 mum - 0.2 mm ``small suspended particulate'' and the >0.2-2 mm ``mesozooplankton'' fractions, with the former considered likely food particle size for the latter. A clear pattern of delta13C depletion occurring in each fraction at middle and inner shelf stations was consistent with two sequential northward pulses of surface oil slicks from DWH. Relative to early June, an isotopic shift of -1 to -3 0/00 (toward weathered and fresh oil, -27.23 ± 0.03 0/00 and -27.34 ± 0.34 0/00, respectively) occurred during the peak of areal coverage of oil over the sites in late June 2010. Recovery of this depletion was 2-4 wks. A third pulse of residual oil occurred in late July, and depleted delta13C was observed in mid-August at the furthest offshore stations. Depletion and recovery cycles on the order of a few weeks are consistent with published warm water petroleum hydrocarbon decay time-scales. Carbon isotopic depletion in both surface and bottom samples suggests trophic transfer of oil carbon into the planktonic food web. A similar response found in benthic communities around natural seeps suggests that carbon isotopic shifts in the plankton fractions are likely due to the duration and magnitude of depleted carbon released into the system. These data provide strong evidence that labile fractions of the oil extended throughout the shallow water column during northward slick transport and that this carbon was processed at least two trophic levels beyond prokaryotic hydrocarbon consumers.
Article
Full-text available
Despite the ecological and economic importance of western Atlantic Ocean lutjanid species, little is known about their larval stage. Pelagic larval distribution, abundance, growth, mortality, and spawning patterns of 6 western Atlantic snapper species were examined from ichthyoplankton samples collected monthly over 2 yr along a transect spanning the east-west axis of the Straits of Florida (SOF). Successful spawning occurred primarily from July to September when water temperatures were warmest and larvae were most abundant in the upper 50 m towards the east or west sides of the SOF. Species-specific variability in spatiotemporal larval patterns tracked adult life history characters. Larvae of species associated with shallow coral reefs were spawned in the waning half of the lunar cycle (third quarter to new moon), were most abundant in the 0 to 25 m depth range, and where cross-SOF distributions were not uniform, were distributed mainly towards the eastern SOF. Larvae of deeper-dwelling species exhibited lower mortality and no lunar pattern in spawning (Etelis oculatus only), were distributed deeper in the water column and occurred progressively deeper with ontogeny, and where cross-SOF distributions were not uniform, were most abundant in the western SOF. Despite species-specific variability in spatial distributions and equivalent east-west mortality rates, at least one measure of larval growth in 4 of 6 species of snapper revealed significantly faster growth in the western versus the eastern SOF, which may be related to higher prey availability in the west. Results of this study provide insight into the pelagic phase of 6 important snapper species, with implications for understanding adult populations.
Article
Full-text available
We report delayed effects on the growth and marine survival of pink salmon Oncorhynchus gorbuscha, which were exposed to oil as embryos under conditions similar to those observed after the 'Exxon Valdez' oil spill. Pink salmon eggs were incubated in water that became contaminated with polynuclear aromatic hydrocarbons (PAHs) after percolating through gravel coated with weathered oil. Weathering ensured that the PAH composition of the water was dominated by alkyl-substituted naphthalenes and larger compounds. Most survivors of the exposures appeared healthy, and were released to the marine environment with coded-wire tags. Their survival was evaluated when they returned at maturity 2 yr later. Other survivors, also healthy in appearance, were retained in net pens to measure delayed effects on growth during the early juvenile stage. Pink salmon exposed to an initial concentration of total PAH equal to 5.4 ppb experienced a 15 % decrease in marine survival compared to unexposed salmon. A delayed effect on growth was measured in juvenile salmon that survived embryonic exposure to doses as low as 18 ppb PAH. Reductions in juvenile growth could account for the reduced marine survival observed in the released fish. The demonstration of delayed effects on growth and survival support claims of delayed effects in pink salmon after the 'Exxon Valdez' oil spill, and indicate the potential for population-level effects resulting from embryonic exposure to oil.
Article
The life cycles of fishes are complex and varied, and knowledge of the early life stages is important for understanding the biology, ecology, and evolution of fishes. In Early Life History of Marine Fishes, Bruce S. Miller and Arthur W. Kendall Jr., bring together in a single reference much of the research available and its application to fishery science-knowledge increasingly important because for most fishes, adult populations are determined at the earliest stages of life. Clear and well written, this book offers expert guidance on how to collect and analyze larval fish data and on how this information is interpreted by applied fish biologists and fisheries managers.