Technical ReportPDF Available

Rocky reef impacts of the 2016 Kaikōura earthquake: extended monitoring of nearshore habitats and communities to 3.5 years. New Zealand Aquatic Environment and Biodiversity Report No. 253

Authors:

Abstract and Figures

The 7.8 magnitude Kaikōura earthquake in November 2016 caused extensive uplift along approximately 130 km of the north-eastern coastline of the South Island of New Zealand. This resulted in widespread mortality of marine organisms and alteration to the community structure and, in many places, the integrity of intertidal and subtidal rocky reefs. The disturbance adversely affected important taonga and habitat-forming species, such as pāua (Haliotis iris) and bull kelp (Durvillaea spp.), prompting an emergency ban on harvesting shellfish and seaweeds that is still in place. This report describes the results of nearshore reef surveys done at long-term monitoring sites between 2.5 and 3.5 years after the earthquake to assess the community structure and trajectories of recovery of rocky reef communities. A major goal of this work is to provide detailed information for underpinning informed decisions about re-opening fishery closures. The sites were first surveyed in 2017 as part of the Ministry for Primary Industries (MPI) Kaikōura Earthquake Marine Recovery Package. The new results included in this report relate to the fifth and fourth rounds of intertidal and subtidal surveys, respectively. These include (i) intertidal surveys done in November 2019 at 16 sites along the coastline between Oaro and Cape Campbell, encompassing uplift levels between approximately 0 and 6 metres; and (ii) subtidal surveys at 6 sites (2 around the Kaikōura Peninsula and 4 north of Kaikōura, in the Okiwi Bay/Waipapa Bay area) in mid-2019 and mid-2020, encompassing uplift levels between approximately 0.7 and 6 metres.
Content may be subject to copyright.
Rocky reef impacts of the 2016 Kaikōura
earthquake: extended monitoring of
nearshore habitats and communities to 3.5
years
New Zealand Aquatic Environment and Biodiversity Report No. 253
T. Alestra,
S. Gerrity,
R.A. Dunmore,
D. Crossett,
S. Orchard,
D.R. Schiel
ISSN 1179-6480 (online)
ISBN 978-1-99-100331-7 (online)
March 2021
Requests for further copies should be directed to:
Publications Logistics Officer
Ministry for Primary Industries
PO Box 2526
WELLINGTON 6140
Email: brand@mpi.govt.nz
Telephone: 0800 00 83 33
Facsimile: 04-894 0300
This publication is also available on the Ministry for Primary Industries websites at:
http://www.mpi.govt.nz/news-and-resources/publications
http://fs.fish.govt.nz go to Document library/Research reports
© Crown Copyright – Fisheries New Zealand
TABLE OF CONTENTS
EXECUTIVE SUMMARY 1
1. INTRODUCTION 3
2. METHODS 4
2.1 Survey design 4
2.2 Intertidal community surveys 6
2.3 Subtidal community surveys 6
3. RESULTS 7
3.1 Intertidal benthic community structure 7
3.2 Abundance of key intertidal taxa 11
3.2.1 Large brown algae 11
3.2.2 Fleshy red algae 17
3.2.3 Relationship between large brown algae and fleshy red algae 18
3.2.4 Coralline red algae 20
3.2.5 Limpets 21
3.3 Subtidal community structure 24
4. DISCUSSION 36
4.1 Intertidal rocky reefs 36
4.2 Subtidal rocky reefs 39
4.3 Conclusions 40
5. ACKNOWLEDGMENTS 40
6. REFERENCES 40
7. APPENDICES 43
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 1
EXECUTIVE SUMMARY
Alestra, T.; Gerrity, S.; Dunmore, R.A.; Crossett, D.; Orchard, S.; Schiel, D.R. (2021).
Rocky reef impacts of the 2016 Kaikōura earthquake: extended monitoring of nearshore
habitats and communities to 3.5 years.
New Zealand Aquatic Environment and Biodiversity Report No. 253. 46 p.
The 7.8 magnitude Kaikōura earthquake in November 2016 caused extensive uplift along
approximately 130 km of the north-eastern coastline of the South Island of New Zealand. This resulted
in widespread mortality of marine organisms and alteration to the community structure and, in many
places, the integrity of intertidal and subtidal rocky reefs. The disturbance adversely affected important
taonga and habitat-forming species, such as pāua (Haliotis iris) and bull kelp (Durvillaea spp.),
prompting an emergency ban on harvesting shellfish and seaweeds that is still in place. This report
describes the results of nearshore reef surveys done at long-term monitoring sites between 2.5 and 3.5
years after the earthquake to assess the community structure and trajectories of recovery of rocky reef
communities. A major goal of this work is to provide detailed information for underpinning informed
decisions about re-opening fishery closures. The sites were first surveyed in 2017 as part of the Ministry
for Primary Industries (MPI) Kaikōura Earthquake Marine Recovery Package. The new results included
in this report relate to the fifth and fourth rounds of intertidal and subtidal surveys, respectively. These
include (i) intertidal surveys done in November 2019 at 16 sites along the coastline between Oaro and
Cape Campbell, encompassing uplift levels between approximately 0 and 6 metres; and (ii) subtidal
surveys at 6 sites (2 around the Kaikōura Peninsula and 4 north of Kaikōura, in the Okiwi Bay/Waipapa
Bay area) in mid-2019 and mid-2020, encompassing uplift levels between approximately 0.7 and
6 metres.
The results of these recent surveys are presented in the context of previous surveys to give a clear
indication of the status and recovery of rocky reef communities. The intertidal surveys showed that
three years after the earthquake all uplifted reefs were still largely unvegetated, with diverse algal
communities found only in the lowest tidal zone. High intertidal areas had limpets and occasional
ephemeral algae but remain barren. Similarly, the mid-tide zone had grazing invertebrates, occasional
ephemeral algae, and occasional small recruits of large brown algae such as Hormosira banksii, but
these algae were burned off in the warmer months. In the low intertidal zone, the presence and
abundance of habitat-forming large brown algae (primarily Durvillaea spp., Carpophyllum
maschalocarpum, Cystophora spp., and Marginariella boryana) varied across uplift levels, with the
greatest abundance at control and low-uplift (under 1 m) sites and the lowest abundance at high-uplift
(up to 6 m) sites. The major noteworthy features of algal changes in the low intertidal zone were: (i)
bull kelp canopy cover remained low at most sites. Their pre-earthquake abundance (as detected by the
initial surveys of uplifted areas immediately post-earthquake) was high in most places; (ii) in many
places, bull kelp was replaced by other large brown algae, primarily Carpophyllum maschalocarpum,
but also a suite of other low-shore fucoids; and (iii) over the last survey period, there was replacement
of large brown algae by fleshy red algae in many places, so their recovery has been poor. In fact, there
was a negative relationship between the covers of large brown algae and fleshy red algae, which
accounted for 10% of the variability in the abundance of large brown algae across all sites in November
2019. Pre-earthquake data show that algal communities at medium- and high-uplift sites were not
dominated by fleshy red algae before the earthquake. Fleshy reds most likely benefitted from the high
mortality of large brown algae following the earthquake and their widespread expansion is now
precluding recruitment of large brown algae.
Coralline algae, which play an important role in the settlement and early survival of invertebrates such
as pāua and cat’s eye snails (Lunella smaragda), were abundant in the low tidal zone at most sites. In
contrast to the slow-recovering large algae, broadcast-spawners, especially a suite of limpets (mostly
2 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
Cellana spp.), recruited heavily within a couple of years post-earthquake. Their abundance was
unrelated to the degree of uplift but was highly variable among sites. Community patterns, taking
account of all the species encountered and their abundances, still showed a clear separation among sites
depending on their degree of uplift. This is a clear indication that ‘recovery’ to pre-earthquake
conditions is far from complete.
Subtidally, there was some recovery of seaweeds and invertebrates at Waipapa Bay, the area with the
highest uplift and most evident earthquake damage, but there were extensive areas of bare rock still
present. There were two striking differences compared with our earlier post-earthquake surveys: (i)
there was a decrease in large brown algae at some sites around the Kaikōura Peninsula and at Okiwi
Bay. This decline may have been due to altered wave dynamics following the uplift, marine heatwaves,
and/or scour due to movement of cobble, gravel, or sand substrates; (ii) in at least one site, there was a
replacement of stands of large brown algae by fleshy red algae (similar to that seen in the low intertidal
zone in some areas). This has resulted in considerable amounts of drifting red algae in shallow areas,
which may prove to be beneficial as food for passive grazers such as pāua.
The physical habitats themselves have continued to change. Intertidal reefs and boulder fields, which
mostly comprise soft sedimentary rock, are continuing to erode and break up. Gravel movement and
accumulation were evident in both the intertidal and subtidal zones, sometimes infilling large areas of
reef and burying resident organisms. Shifts in sand and gravel can delay the recovery of benthic
communities by scouring rock surfaces and smothering organisms and are indicative of a very dynamic
physical environment. Reef erosion is no doubt contributing to the poor recovery of benthic
communities in many areas.
This and related studies are showing a clear picture of the difficulties in resilience and recovery after a
cataclysmic event. Decades of small-scale disturbance experiments along the coast of the South Island
have shown that recovery can be very slow. For example, clearances of several square meters of large
brown algal canopies can take up to 8 years to regain their original cover, and even longer for full
communities to return. ‘Resilience’ usually means a quick recovery to a previous state. This is clearly
not the case along the earthquake coast. ‘Recovery’ also implies a return to a previous state. This has
not yet occurred. The major impediments to recovery are continuing changes to reef integrity, especially
erosion and gravel movement, and poor connectivity between large brown algal populations. This is
especially true for bull kelp, which have a very limited reproductive season and only short-range
propagule dispersal except through drifting, reproductive adults. A slow recovery was expected, and
further changes to algal-dominated communities are anticipated over the next few years. The recovery
of bull kelp populations will be a clear signal that a major pre-earthquake configuration has returned.
This research has been presented regularly to local community groups, iwi, the commercial pāua fishing
industry, and resource managers to facilitate a re-opening strategy for the Kaikōura coast.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 3
1. INTRODUCTION
The 2016 Kaikōura earthquake caused extensive coastal uplift along about 130 km of coastline (Clark
et al. 2017, Hamling et al. 2017), severely affecting highly productive nearshore ecosystems (Schiel et
al. 2018, Schiel et al. 2019, Gerrity et al. 2020, Thomsen et al. 2020). The Kaikōura coastline is home
to numerous taonga species which support customary, recreational, and commercial fisheries. It is
important to monitor the health of the wider ecosystem, including abundance of biogenic habitats and
seaweed communities, in addition to stock assessments. Extensive field surveys were done between
2017 and 2018 as part of the Ministry for Primary Industries (MPI) Kaikōura Earthquake Marine
Recovery Package to assess the impacts of the earthquake on rocky intertidal and shallow subtidal
biogenic habitats (Alestra et al. 2019). This research provided a detailed assessment of the state of rocky
reef systems along the uplifted coastline and of the impacts of the earthquake on species of ecological,
cultural, and/or commercial significance (e.g., pāua, bull kelp, etc.). It also established a baseline to
gauge successional sequences and recovery dynamics. In summary, the initial research programme
found that the coastline had undergone significant changes in the structure and function of rocky
intertidal and subtidal algal and invertebrate communities and was experiencing variable states of
recovery. Even small changes in tidal elevation as a result of coastal uplift affected habitat-forming
algae and invertebrate abundance. Nearly all intertidal algal and invertebrate taxa experienced reduced
abundance in the months and years following the earthquake compared with pre-earthquake levels.
Although the subtidal communities were less affected, there was a significant decrease in the abundance
of large brown algae, and an increase in newly emerged bare rock. In both intertidal and subtidal zones,
erosion and the presence of mobile substrata such as gravel and sand likely inhibited recovery at some
sites. Despite these impacts, clear signs of post-earthquake reproduction, settlement, and recruitment of
pāua and large brown algae were documented, suggesting some potential for recovery.
The work done as part of the Kaikōura Earthquake Marine Recovery Package assessed the initial
responses of rocky reef systems up to 16 months following the earthquake (to March 2018). To monitor
long-term recovery trajectories and better understand the outcomes of this catastrophic event, further
intertidal and subtidal surveys were carried out in late 2018/early 2019 (described by Alestra et al. 2020)
and between late 2019 and mid-2020 (described in this report). The objectives of this research extension
were to continue monitoring for the original objectives of the 2017 contract:
Overall objective
1. To quantify the impact of the Kaikōura earthquake on rocky reef intertidal and subtidal
fauna and either quantify, or establish long-term monitoring sites to quantify, the
recovery from the earthquake in order to inform future marine management decisions.”
Specific objectives
1. Determine the impact of the Kaikōura earthquake on rocky reef systems, this may also
include sub-lethal responses where methodologies to test this exist.
2. Assess long-term monitoring sites to quantify the recovery from the earthquake in order
to inform future marine management decisions.
3. Compare impacts across the range of uplift and habitats impacted on the rocky shore.
4. Continue monitoring sediment cover to suggest causation between short-term uplift and
potentially longer-term increased sedimentation as a result of the Kaikōura earthquake.
5. Where possible include local participation in the recovery package work and specifically
refer to relevant South Island iwi (Te Rūnanga o Kaikōura and Te Tau Ihu), and local
community
This report provides an updated assessment of the state of intertidal (up to 3 years post-earthquake) and
subtidal rocky reef communities (up to 3.5 years post-earthquake). This information will provide a
context for management decisions, in particular those regarding the re-opening strategy for shellfish
4 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
(especially pāua, Haliotis spp.) and seaweed harvest, which has been proposed for late 2021. This work
will also contribute to a very limited pool of long-term studies about post-earthquake recovery of coastal
systems worldwide. Although coastal uplift of this scale is unprecedented, studies from Chile
(Barrientos & Ward 1990, Castilla & Oliva 1990, Jaramillo et al. 2012, Castilla et al. 2010, Castilla
1988) have documented catastrophic effects of seismic disturbances to coastal ecosystems. These
studies consistently show a suite of severe immediate impacts of coastal uplift on marine communities,
followed by a long recovery period of several years. As well, numerous disturbance studies by our
group have shown that even local-scale disturbances to algal canopies can take 8 years to recover (e.g.,
Lilley & Schiel 2006, Schiel & Lilley 2007, Tait & Schiel 2011). This research provides quantitative
survey data to improve our understanding of complex recovery dynamics which follow coastal uplift.
These extended surveys also provide added baselines and references for other research underway. This
uses a more holistic approach based on experimental work and wide-scale habitat mapping to tease out
biological and physical mechanisms driving and underpinning the recovery of earthquake-affected reefs
(Project title: “Community concerns, key species and wahi taonga recovery trajectories of the marine
ecosystem from the Kaikōura earthquakes”, MBIE, UOCX1704).
2. METHODS
2.1 Survey design
Intertidal and subtidal surveys were done at a set of sites divided across eight locations which have been
monitored since the earliest round of post-earthquake surveys in mid-2017 (Alestra et al. 2019,
Figure 1). Replicate sites within each location were separated by at least 500 m. These sites were
originally selected to encompass the length of the earthquake-impacted coastline and represent different
levels of uplift (Alestra et al. 2019). Following the uplift categorisation used in previous reports (Alestra
et al. 2019, 2020), the sites are divided into four uplift groups on the basis of uplift information obtained
from GNS Science (K. Clark, personal communication) and our own calculations (Orchard et al.,
unpublished data): control (C no uplift); low uplift (L 0.5 to 1.5 m); medium uplift (M – 1.5 to 2.5
m); high uplift (H 4 to 5.5 m, Figure 1). Recent calculations by Gerrity et al. (2020) showed that rocky
reefs occupy 48 km of the total length of the earthquake-impacted coastline (c.130 km). Three of the
uplift categories used as part of the uplift categorisation are represented and account for 39 km of rocky
reef habitat, whereas only 2 km experienced uplift beyond 4 m (Figure 2).
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 5
Figure 1: The sites used for repeated intertidal and subtidal monitoring were divided across 8 locations
displayed in this map. The information in parentheses indicates the number of intertidal (int)
and subtidal sites (subt) per location. Different colours are used for the four uplift categories:
control (white), low uplift (green), medium uplift (orange), high uplift (red).
Figure 2: Kilometres of rocky reef habitat that experienced uplift levels in line with our uplift
characterisation system (white = control, green = low uplift, orange = medium uplift, red = high
uplift).
6 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
2.2 Intertidal community surveys
Intertidal community surveys were done in November 2019, three years after the Kaikōura earthquake,
at 16 sites across 8 locations and encompassing the degrees of uplift (Figure 1). The methodology
applied in previous post-earthquake sampling was used (Alestra et al. 2019). At each site, sampling was
done along 30-m transects previously established within the current (i.e., post-earthquake) tidal
elevation zones. There was one transect in each of the post-earthquake high, mid (where present), and
low tidal zones. Algae and invertebrates were identified to species level when feasible or to the finest
possible taxonomic resolution, and their abundances were recorded in ten haphazardly located 1-m2
quadrats placed along each transect in each zone. Abundances were expressed as percentage cover for
sessile organisms and as counts for mobile animals.
Data generated by the November 2019 surveys were analysed with univariate (ANOVA) and
multivariate techniques (PERMANOVA) testing for differences among uplift groups and sites
(Anderson et al. 2008, Clarke & Warwick 2001). To provide a comprehensive and easily understandable
overview of the main patterns in intertidal community structure, the results included in this report
mainly relate to broad taxonomic groups (i.e., groups of species sharing common morphological and
life-history traits) and not to individual species.
These include:
large brown algae, which are the dominant habitat-forming species along this coastline;
fleshy red algae, which account for a large proportion of the diversity in intertidal algal
communities;
coralline red algae, which are also habitat-formers and an important invertebrate settlement
substrate;
limpets, which are the most abundant large intertidal grazers along this coastline.
In light of the opposite patterns of abundance of large brown and fleshy red algae in relation to uplift,
the relationship between these two groups was explored three years after the earthquake. Using the
November 2019 low zone data, a mixed-effects linear regression model was built, with the cover of
large brown algae as a response variable and that of fleshy red algae as a fixed effect. Sites were treated
as random effects to account for the spatial structure of the surveys and partition among- and within-
site variability. Given the large variability in the data, a quantile regression model was used to perform
the same analysis across five different quantiles and test whether the relationship remained stable across
the entire range of the data. Waipapa Bay 1 was excluded from both regression analyses because both
large brown and fleshy red algae were absent at this site three years after the earthquake.
2.3 Subtidal community surveys
Subtidal community surveys were done between May and July 2020, approximately 3.5 years after the
Kaikōura earthquake, at 6 sites selected across 4 locations: Waipapa Bay, Okiwi Bay, and Kaikōura
Peninsula North and South (Figure 1, Appendix 1). These sites encompassed degrees of uplift between
0.5 and 6 m. The low-uplift (around 0.6 m) sites around the Kaikōura Peninsula had no earthquake
damage (Alestra et al. 2019, 2020) and were considered as controls. Sampling followed the
methodology of previous surveys, assessing algae, and sessile and mobile invertebrate community
composition and abundances (Alestra et al. 2019). At each site:
three 50 m transects perpendicular to the shore starting from the low tidal mark were re-
surveyed. Subtidal transects were usually located directly offshore of intertidal transects and
had been marked using GPS;
substrate type and the abundance of all algae, sessile invertebrates, mobile invertebrates, and
triplefin fish were recorded for 20 × 5 m2 sections along each transect (each section was 1 m
either side of the transect and 2.5 m in length). Taxa were usually identified to species level,
and when this was not achievable they were given descriptive names;
the sizes of pāua (Haliotis iris and Haliotis australis) were measured using automated calipers
that also recorded the depth of occurrence;
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 7
the abundance of all large fish was recorded for 5 × 20 m2 sections along each transect (each
section was 1 m either side of the transect, 2 m above the seafloor, and 10 m in length);
video footage was recorded along transects.
As for previous surveys, subtidal data were filtered to include only quadrats with at least 50% rock
coverage (cobble, boulder, or bedrock). This was done to eliminate the large variability in communities
due to some transects having extensive areas of sand. By eliminating the sandy/gravel quadrats, a more
accurate comparison of the rocky reef communities between transects, sites, and uplift could be made.
The removal of the sand-dominated quadrats resulted in a reduction in the number of replicates,
although most transects (63 out of 67) still had at least 10 quadrats per transect. Numbers of quadrats
per site used in analyses are provided in Appendix 1.
Differences in subtidal community structure and grouped taxa with respect to uplift, site, and transect
were analysed statistically using a distance-based permutational analysis (PERMANOVA). The
PERMANOVA design had four factors; Uplift (fixed, 3 levels: low, medium, high), Survey (fixed, 4
levels), Site (random, nested within Uplift, 6 levels), and Transect (random, nested within Site, 3 levels).
Data were square-root transformed to de-emphasise the influence of abundant organisms, and analyses
were based on Bray-Curtis similarities. For the Bray-Curtis similarity matrices, a dummy variable of
0.01 was used so that double zero data were treated as 100% similar. SIMPER was used to identify taxa
contributing to dissimilarity between communities. To visualise the differences between communities,
principal coordinates analyses (PCO) were run on the resemblance matrices created from distances
among centroids for the unique Site/Transect and Site combinations. Taxa that had a correlation greater
than 0.6 with the PCO axes were displayed as vectors in the PCO plots.
3. RESULTS
3.1 Intertidal benthic community structure
Three years after the earthquake, intertidal reefs remained mostly bare, with algal communities
surviving only in the lowest areas (Figure 3).
Figure 3: Characteristic appearance of post-earthquake intertidal reefs, with extensive bare areas and
algal cover confined to a narrow band in proximity of the low tide mark.
As in previous years (Figures 4 A-D, F-I, K-N), 36 months after the earthquake most of the algal
biomass was found in the post-earthquake low zone on uplifted reefs (Figure 4 O), whereas the high
and the mid zones were generally devoid of algae (Figure 4 E, J). Low algal abundance in the high zone
is typical of rocky intertidal habitats because physical conditions in this area are too harsh for most
seaweeds, but the mid zone environment can support diverse algal communities. However, under all
8 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
levels of uplift, mid zone areas continued to be mostly unvegetated three years after the earthquake
(Figure 4 J). In the low zone, algae were abundant in all uplift groups, and extensive covers of large
brown algae characterised communities at the control and low-uplift sites, whereas fleshy red algae
were more dominant at the medium- and high-uplift sites (Figure 4 O).
Multivariate analyses showed that in November 2019 there was a significant Uplift effect on benthic
community composition in the post-earthquake high zone (Uplift: Pseudo-F3,12 = 2.75, P < 0.05,
Figure 5 A). However, these differences reflected occasional blooms in the abundance of ephemeral
algae rather than a real earthquake legacy. In particular, the control and the low-uplift groups differed
from the medium-uplift group because of higher covers of ephemeral green (Ulva spp.) and red algae
(Pyropia spp.), respectively (Appendix 2 A). The medium- and high-uplift groups did not differ from
each other and there was significant variability in the structure of benthic communities among sites
within each uplift group (Pseudo-F12,144 = 6.94, P < 0.001, Figure 5 A).
Long-lasting earthquake impacts were more evident in the post-earthquake mid zone, where abundant
algal communities could only be found at the control sites (Appendix 2 B). As a result, the control group
differed significantly from the low- and medium-uplift groups (Uplift: Pseudo-F2,8 = 3.45, P < 0.05,
Figure 5 B) and there was also significant variability in the structure of benthic communities among
sites in the low- and medium-uplift groups (Pseudo-F8,99 = 6.08, P < 0.01, Figure 5 B).
Finally, in the post-earthquake low zone, the composition of benthic communities was different in the
low-uplift group (where large brown algae, particularly Carpophyllum maschalocarpum, were
dominant) compared with the medium- and high-uplift groups (which were characterised by high covers
of red algae: Uplift: Pseudo-F3,12 = 1.93, P < 0.01, Figure 5 C, Appendix 2 C). No other groups differed
from the others and there was significant variability in the structure of benthic communities among sites
within each uplift group (Pseudo-F12,144 = 10.08, P < 0.01, Figure 5 C). Waipapa Bay 1 was the only site
almost completely devoid of algae in the low zone three years after the earthquake (Figure 5 C).
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 9
Figure 4: Mean abundance of the main algal groups (+SE) and of sessile invertebrates across uplift levels 6, 12, 16, 24, and 36 months after the earthquake. Only
the high and the low zone were sampled at high-uplift sites.
10 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
Figure 5: Principal coordinates analysis (PCO) plots showing differences in the composition of benthic
communities in the post-earthquake high (A), mid (B), and low zones (C) across sites with
different degrees of uplift 36 months after the earthquake. The symbols represent the centroid
of each site and the colours the different levels of uplift (white = no uplift, green = low uplift,
yellow = medium uplift, red = high uplift). Sites are ordered north to south within each uplift
group. Only the high and the low zone were sampled at high-uplift sites.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 11
3.2 Abundance of key intertidal taxa
Because there was very limited recovery of algae in the post-earthquake high and mid zones of uplifted
reefs three years after the earthquake, Sections 3.2.1, 3.2.2, and 3.2.4 describe the recovery of brown
and red algae in the post-earthquake low zone. Section 3.2.3 describes the relationship between large
brown algae and fleshy red algae. Section 3.2.5 focuses on temporal trends in the abundance of the main
intertidal grazers (limpets) across all tidal zones.
3.2.1 Large brown algae
In the post-earthquake low zone, Carpophyllum maschalocarpum was the most abundant species of
large brown algae three years after the earthquake (about 25% average cover across all sites), followed
by Cystophora scalaris, Durvillaea spp., and Marginariella boryana (which had average covers
between 3 and 5% across all sites). In November 2019, the abundance of large brown algae decreased
with increasing uplift across the four groups, which all differed from each other (Uplift: F3,12 = 48.53,
P < 0.001, Figure 6). The control group had the highest average cover of large brown algae (77%),
followed by the low-uplift group (59%), the medium-uplift group (36%), and the high-uplift group
(7%). These results are in line with those from previous sampling dates, showing a steady increase in
the abundance of large brown algae in the low- and medium-uplift groups, and a lack of recovery in the
high-uplift group. The extended time series also shows that the low-uplift group has maintained
abundances of large brown algae in line with pre-earthquake levels across two consecutive years, and
that the control sites are recovering after high mortality during the hot summer and heat wave of 2017–
2018 (Figure 6).
Figure 6: Time series of the mean percentage cover (±SE) of large brown algae per square metre in the
post-earthquake low zone across uplift levels. The dotted blue line indicates the average
abundance of large brown algae in the pre-earthquake low zone across sites sampled in
November 2016 (see Alestra et al. 2019). n = number of sites in each uplift group. *n = 5 after
12 months.
12 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
Three years after the earthquake, the different sites within each group had a similar cover of large brown
algae (Site: F12,144 = 0.94, P = 0.51, Figure 7). All low-uplift sites had a cover of large brown algae
greater than 48% (Figure 7 B), whereas all medium- and high-uplift sites were below this (Figure 7 C,
D). As in previous sampling events, Waipapa Bay 1 was the only site where large brown algae were
completely absent (Figure 7 D). Comparisons with pre-earthquake data show that the low-uplift sites
have returned or are close to covers in line with pre-earthquake abundances (Figure 7 B), whereas
medium- and high-uplift sites are still well below pre-earthquake levels (Figure 7 C, D).
Figure 7: Time series of the mean percentage cover (±SE) of large brown algae per square metre in the
post-earthquake low zone across sites with no (A), low (B), medium (C), and high uplift (D). For
the sites sampled in November 2016 (see Alestra et al. 2019), the average abundance of large
brown algae in the pre-earthquake low zone is displayed in the grey panels. At Omihi 1 and 2
(panel C) the low zone could not be sampled 12 and 16 months after the earthquake.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 13
Comparisons with pre-earthquake data also show that post-earthquake assemblages of large brown
algae are no longer dominated by bull kelp (Durvillaea spp.) but instead other species of fucoids
(primarily Carpophyllum maschalocarpum) represent the vast majority of large brown algal cover in
November 2019 (Figures 8 and 9).
Figure 8: Large brown algae assemblages dominated by bull kelp (Durvillaea poha in the top picture) and
mixed fucoids (mainly Carpophyllum maschalocarpum in the bottom picture).
14 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
Figure 9: Changes in the relative abundance of bull kelp (Durvillaea spp.) and other species of fucoids
(mixed fucoids - primarily Carpophyllum maschalocarpum, Cystophora scalaris, Marginariella
boryana, and Lessonia variegata) in the pre- (November 2016) and post-earthquake low zone
(November 2019).
Shifts in the composition of large brown algae assemblages resulted from a post-earthquake decline in
the abundance of bull kelp combined with a simultaneous increase in the cover of mixed fucoids. Most
sites had declining abundances of bull kelp following the earthquake (Figure 10), with no sign of
recovery in the area of highest uplift, where bull kelp was completely extirpated (Figure 10 D). At the
same time, the cover of mixed fucoids increased at almost all sites (Figure 11), particularly where there
was no or low uplift (Figure 11 A and B). Three years after the earthquake, the abundance of mixed
fucoids decreased with increasing uplift across the four groups (Uplift: F3,12 = 23.4, P < 0.001) and was
highest in the control group (65%) and lowest in the high-uplift group (7%, Figure 11). Whereas for
bull kelp, there were no significant differences among uplift levels in November 2019 (Uplift: F3,10 =
0.86, P = 0.48), although it remained absent in the high-uplift group, and its cover ranged between 9
and 12% in the others (Figure 10).
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 15
Figure 10: Time series of the mean percentage cover (±SE) of bull kelp (Durvillaea spp.) per square metre
in the post-earthquake low zone across sites with no (A), low (B), medium (C), and high uplift
(D). For the sites sampled in November 2016 (see Alestra et al. 2019), the average abundance of
bull kelp in the pre-earthquake low zone is displayed in the grey panels. At Omihi 1 and 2 (panel
C) the low zone could not be sampled 12 and 16 months after the earthquake. Kaikōura North
1 and South 1, where bull kelp was not present both before and after the earthquake, are not
included in this figure.
16 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
Figure 11: Time series of the mean percentage cover (±SE) of mixed fucoids (primarily Carpophyllum
maschalocarpum, Cystophora scalaris, Marginariella boryana, and Lessonia variegata) per
square metre in the post-earthquake low zone across sites with no (A), low (B), medium (C),
and high uplift (D). For the sites sampled in November 2016 (see Alestra et al. 2019), the average
abundance of mixed fucoids in the pre-earthquake low zone is displayed in the grey panels. At
Omihi 1 and 2 (panel C) the low zone could not be sampled 12 and 16 months after the
earthquake.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 17
3.2.2 Fleshy red algae
In November 2019, the medium- and high-uplift groups had the highest cover of fleshy red algae in the
post-earthquake low zone (47% and 50%, respectively) and the low-uplift group had the lowest (17%,
Figure 12), but the analysis could not detect significant differences among uplift groups (Uplift:
F3,12 = 1.93, P = 0.18) because these were outweighed by the large variability among sites within all
groups (F12,144 = 8.15, P < 0.001, Figure 13). These patterns are in line with those of previous years,
with high abundances of fleshy red algae in areas with uplift between 1.5 and 5.5 m, although their
cover did not increase as steadily between 2018 and 2019 at many medium- and high-uplift sites
(Figure 13).
Figure 12: Time series of the mean percentage cover (±SE) of fleshy red algae per square metre in the post-
earthquake low zone across uplift levels. The dotted blue line indicates the average abundance
of fleshy red algae in the pre-earthquake low zone across sites sampled in November 2016 (see
Alestra et al. 2019). n = number of sites in each uplift group. *n = 3 after 12 and 16 months.
18 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
Figure 13: Time series of the mean percentage cover (±SE) of fleshy red algae per square metre in the post-
earthquake low zone across sites with no (A), low (B), medium (C), and high uplift (D). For the
sites sampled in November 2016 (see Alestra et al. 2019), the average abundance of fleshy red
algae in the pre-earthquake low zone is displayed in the grey panels. At Omihi 1 and 2 (panel
C) the low zone could not be sampled 12 and 16 months after the earthquake.
3.2.3 Relationship between large brown algae and fleshy red algae
Regression analysis highlighted a negative relationship between the cover of large brown algae and that
of fleshy red algae (slope: -0.26, P < 0.001, Figure 14 A). This relationship accounted for 10% of the
variability in the abundance of large brown algae in November 2019. The whole model (accounting
also for site by site differences) explained 36% of the variability in the abundance of large brown algae.
Quantile regression analyses confirmed the presence of a strong negative relationship between the two
groups across five different quantiles (q10 slope -0.25, P <0.001; q25 slope -0.35, P <0.001; Q50 slope
-0.41, P <0.001; q75 slope -0.44, P <0.001; q90 slope -0.4, P <0.01, Figure 14 B).
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 19
Figure 14: Relationship between the abundance of large brown and fleshy red algae three years after the
earthquake estimated through mixed effects (A) and quantile regression models (B). Regression
lines are displayed for significant relationships. Symbol colours indicate different levels of uplift
(white = no uplift, green = low uplift, yellow = medium uplift, red = high uplift). Data from
Waipapa Bay 1, where both large brown and fleshy red algae were not present in November
2019, were not included in this analysis.
20 Kaikōura earthquake rocky reef impacts Fisheries New Zealand
3.2.4 Coralline red algae
In November 2019, control, low-, and medium-uplift groups had similar covers of coralline red algae
(between 43–51%), whereas the mean for the high-uplift group was 22% (Figure 15). However, the
analysis found no significant differences among uplift groups (F3,12 = 1.96, P = 0.17). The extended time
series shows a slight decline in the abundance of coralline algae between 24 and 36 months post-
earthquake, with all groups remaining below the pre-earthquake baseline (Figure 15). In November
2019, there was also significant variability among sites in all groups, but the two control sites did not
differ significantly from each other (F12,144 = 7.35, P < 0.001). Across all sites, the cover of corallines
remained stable or declined between 2018 and 2019. Waipapa Bay 1 was the only site where coralline
algae were completely absent (Figure 16).
Figure 15: Time series of the mean percentage cover (±SE) of coralline red algae per square metre in the
post-earthquake low zone across uplift levels. The dotted blue line indicates the average
abundance of coralline red algae in the pre-earthquake low zone across sites sampled in
November 2016 (see Alestra et al. 2019). n = number of sites in each uplift group. *n = 5 after
12 months.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 21
Figure 16: Time series of the mean percentage cover (±SE) of coralline red algae per square metre in the
post-earthquake low zone across sites with no (A), low (B), medium (C), and high uplift (D). For
the sites sampled in November 2016 (see Alestra et al. 2019), the average abundance of coralline
red algae in the pre-earthquake low zone is displayed in the grey panels. At Omihi 1 and 2
(panel C) the low zone could not be sampled 12 and 16 months after the earthquake.
3.2.5 Limpets
In November 2019, the medium-uplift group had limpet densities over 50 per m2, whereas limpet
abundances in all other groups were between 12 and 24 individuals per m2 (Figure 17). However, the
analysis found no significant differences among uplift groups (F3,12 = 1.54, P = 0.25) and significant
differences among sites in all groups (F12,144 = 6.91, P < 0.001, Figure 18). High limpet densities in the
medium-uplift group were due to very high numbers at a single site (Okiwi Bay, Figure 18 C). The drop
in limpet numbers in the control group (Figure 17) did not reflect a widespread decline in the abundance
of all limpet species, but simply the absence of large clusters of Siphonaria spp. in November 2019 at
one of the Oaro sites (Figure 18 A).
22 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Figure 17: Time series of the mean number (±SE) of limpets per square metre across uplift levels. The
dotted blue line indicates the average abundance of limpets across sites sampled in November
2016 (see Alestra et al. 2019). n = number of sites in each uplift group. *n = 5 after 12 months.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 23
Figure 18: Time series of the mean number (±SE) of limpets per square metre across sites with no (A), low
(B), medium (C), and high uplift (D). For the sites sampled in November 2016 (see Alestra et al.
2019), the average abundance of limpets is displayed in the grey panels. At Omihi 1 and 2 (panel
C) the low zone could not be sampled 12 and 16 months after the earthquake.
24 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
3.3 Subtidal community structure
General observations during the 2020 subtidal surveys showed minor recovery of seaweeds and
invertebrates at Waipapa Bay (Figure 19), and a decrease in the abundance of large brown algae around
the Kaikōura Peninsula and at Okiwi Bay (Figure 20). There were shifts in sand and gravel distribution
in some transects at Okiwi Bay South and Waipapa Bay (Figure 21), and an overall decline in algae at
one cobble-dominated site (Okiwi Bay South T1). Sites at Waipapa Bay still had large areas of bare
rock that had not been recolonised three and a half years after the earthquake.
Figure 19: Examples of recruitment of encrusting coralline and encrusting red algae (top), brown
(Landsburgia quercifolia) and red algae (middle), and sessile and mobile invertebrates (bottom)
at Waipapa Bay. Photos taken in July 2020.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 25
Figure 20: Subtidal landscape at Okiwi Bay North (Transect 1), showing an area dominated by large
brown algae in 2017 (top) and by red algae in 2020 (bottom).
26 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Figure 21: Examples of gravel and cobble covering algae at Okiwi Bay South (top and right), and remnant
holdfasts of Marginariella boryana (bottom left). Photos taken in May 2019.
There were changes in substrate cover (using all data and not filtered to only include quadrats with at
least 50% rock see page 7 of this report) at some Waipapa Bay and Okiwi Bay sites. The changes
mainly related to the movement of sand and gravel at the sites. Waipapa Bay North and South sites had
declines in sand cover in 2019 and increases in 2020. Gravel cover also fluctuated, particularly at the
south sites. The increase in bedrock at Waipapa Bay South sites is due to sand and gravel cover
decreasing and exposing bedrock, and due to the addition of a different transect in 2018 (Figure 22).
Okiwi South sites also had declines in sand cover since 2017 (from a mean of 13% to 1%) and increases
in cobble (from 14% to 36%). These results agree with observations during the surveys. Other changes
in abundances could be related to slight differences in the positioning of transects.
Percentage covers of some algal groups across sites changed between surveys. There was a decline in
large brown algal cover at Kaikōura Peninsula and Okiwi Bay sites through time, and an increase in red
non-encrusting algae at Okiwi Bay sites (Figure 23). Means of large brown algae declined from 54% to
33% and from 32% to 12% at Kaikōura and Okiwi Bay sites, respectively, whereas red non-encrusting
algae increased from 15% to 32% at Okiwi Bay sites. Although encrusting/turfing algae cover was
similar through time at Kaikōura and Okiwi Bay sites, increases were seen at Waipapa Bay sites (14%
to 38%), along with an increase in red non-encrusting algae (6% to 19%). Some recruitment of large
brown algae was seen around Waipapa Bay, but this was not noticeable in the plots due to the small
sizes of the recruits (Figure 19). Ephemeral green algae (Ulva sp.) had a greater percentage cover at
Okiwi Bay South in 2020 and at Waipapa Bay South in 2018 and 2020 (Figure 23).
There were no clear trends in mobile invertebrate abundances through time at Kaikōura and Okiwi Bay
sites, but Waipapa Bay sites showed increases in numbers (Figure 24). The high numbers of mobile
invertebrates at Waipapa Bay South in 2017 skewed results and were due to a large number of rock
lobsters along one transect, but overall numbers of other mobile invertebrates increased through time.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 27
Numbers of Cook’s turban shells (Cookia sulcata) and both species of pāua (Haliotis iris, H. australis)
increased (Figure 25). Numbers of both pāua species also increased at Okiwi Bay sites (means of 0.06
to 0.26 and 0 to 0.09 for H. iris and H. australis respectively), and kina increased at the Kaikōura South
site (from a mean of 0.6 to 1.5).
Sessile invertebrate cover increased at Kaikōura North (1% to 2%), and this was driven by increases in
sponges and ascidians. There were small increases in sponges and ascidians at Waipapa North and
South, respectively (Figure 24).
Figure 22: Mean percentage cover of substrate types per 5-m2 quadrat at the six sites surveyed between
2017 and 2020. For each pair of bars, the left bar refers to the northern site and the right bar
to the southern site, with locations of the sites labelled below the x-axis. L=Low, M=Medium,
H=High. N = 20. Data are averaged over 3 transects with the exception of 2018 surveys at
Waipapa South, where data are averaged over 4 transects; error bars represent 1 s.e.
Kaikoura Okiwi Waipapa
0
20
40
60
80
100
Bedrock
(% cover)
2017 2019 2020 2017 2018 2019 2020 2017 2018 2019 2020
0
20
40
60
80
100
Boulder
(% cover)
0
20
40
60
80
100
Cobble
(% cover)
0
20
40
60
80
100
Gravel and shell
(% cover)
0
20
40
60
80
100
Sand and silt
(% cover)
LMH
28 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Figure 23: Mean percentage cover of algae per 5-m2 quadrat at the six sites surveyed between 2017 and
2020. For each pair of bars, the left bar refers to the northern site and the right bar to the
southern site. Data were filtered to only include quadrats with at least 50% rock substrate
(cobble, boulder, or bedrock) (n=variable and noted in Appendix 1). Data are averaged over 3
transects with the exception of 2018 surveys at Waipapa South, where data are averaged over
4 transects; error bars represent 1 s.e. Note different scales for greenand all algaeplots.
Kaikoura Okiwi Waipapa
0
50
100
150
200
250
All algae
(% cover)
2017 2019 2020 2017 2018 2019 2020 2017 2018 2019 2020
0
5
10
15
20
25
Green algae
(% cover)
0
20
40
60
80
100
Red foliose/filamentous/
branching algae
(% cover)
0
20
40
60
80
100
Large brown algae
(% cover)
0
20
40
60
80
100
Encrusting/turfing algae
(% cover)
LMH
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 29
Figure 24: Mean percentage cover of sessile invertebrates, sponges, and ascidians, and numbers of mobile
invertebrates and triplefins per 5-m2 quadrat at the six sites surveyed between 2017 and 2020.
For each pair of bars, the left bar refers to the northern site and the right bar to the southern
site. Data were filtered to only include quadrats with at least 50% rock substrate (cobble,
boulder or bedrock) (n=variable and noted in Appendix 1). Data are averaged over 3 transects
with the exception of 2018 surveys at Waipapa South, where data are averaged over 4 transects;
error bars represent 1 s.e. Note change in scales.
0
0.4
0.8
1.2
1.6
Ascidians
(% cover)
0
1
2
3
4
Sponges
(% cover)
0
1
2
3
4
5
All sessile invertebrates
(% cover)
0
2
4
6
All mobile invertebrates
(Number)
Kaikoura Okiwi Waipapa
0
0.2
0.4
0.6
0.8
Tripterygiidae
(triplefins)
(Number)
2017 2019 2020 2017 2018 2019 2020 2017 2018 2019 2020
LM H
30 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Figure 25: Mean number of selected mobile invertebrates per 5-m2 quadrat at the six sites surveyed
between 2017 and 2020. For each pair of bars, the left bar refers to the northern site and the
right bar to the southern site. Data were filtered to only include quadrats with at least 50%
rock substrate (cobble, boulder, or bedrock) (n=variable and noted in Appendix 1). Data are
averaged over 3 transects with the exception of 2018 surveys at Waipapa South, where data are
averaged over 4 transects; error bars represent 1 s.e. Note change in scales.
2017 2019 2020 2017 2018 2019 2020 2017 2018 2019 2020
0
0.05
0.1
0.15
0.2
0.25
Sea stars
(Number)
0
1
2
3
Evechinus chloroticus
(kina)
(Number)
0
2
4
6
Jasus edwardsii
(crayfish)
(Number)
0
0.2
0.4
0.6
Lunella smaragda
(cat's eye snails)
(Number)
0
0.2
0.4
0.6
0.8
1
Cookia sulcata
(Cook's turban)
(Number)
0
0.2
0.4
0.6
0.8
1
Haliotis iris
(black foot paua)
(Number)
0
0.1
0.2
0.3
0.4
Haliotis australis
(yellow foot paua)
(Number)
Kaikoura Okiwi Waipapa
L M H
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 31
Permanova analysis for the subtidal community data showed that Site was significant and Transect was
highly significant (P < 0.001) (Table 1). This indicates there was spatial variability at small (between
transects) and large (between sites) scales. The Survey x Transect (Site(Uplift)) interaction term was
also highly significant, indicating that one or more transects changed differently from each other
between surveys.
Principle coordinate analysis of distance between centroids for the Site combinations showed the degree
of change in communities between surveys (Figure 26). Okiwi Bay North and South, and Waipapa Bay
South communities changed the most between surveys. Communities at Okiwi Bay sites (particularly
south sites) had a directional change towards the right of the plot (Figure 26). The communites on the
right side had less brown algae and more red algae than the communities on the left side of the plot.
Communities at Waipapa Bay showed directional change from the top to the bottom of the plot and this
was primarily driven by increases in several different taxa (i.e., recruitment and recovery of algal and
invertebrate populations).
SIMPER analysis showed that the differences between surveys at Okiwi North were primarily driven
by a reduction in some large brown algae (Marginariella boryana and Lessonia variegata) and an
increase in several red algal taxa. Differences in surveys at Okiwi Bay South were primarily driven by
a reduction in encrusting and turfing corallines, red encrusting algae, some large brown algae (M.
boryana, Landsburgia quercifolia, and Lessonia variegata), and some red foliose algal taxa. The
increase in the green alga Ulva sp. also contributed to the dissimilarity between communities in 2020
and previous years.
Waipapa Bay South sites were dissimilar between surveys primarily due to an increase in encrusting
coralline and encrusting red algae, Ulva sp., and some brown algae (L. quercifolia and Halopteris spp.),
and a decrease in the brown alga Carpophyllum maschalocarpum. The large difference in the Waipapa
Bay South 2017 communities and subsequent surveys was due to a high number of crayfish recorded
in one transect in 2017. Communities at Waipapa North were dissimilar through time due to increases
in encrusting corallines, red encrusting algae, some red foliose algal taxa, and an encrusting orange
sponge.
Table 1: PERMANOVA results for epibiota community data. P values: * < 0.05, ** < 0.01, *** < 0.001.
Source
df
MS
Pseudo-F
P(perm)
Uplift
2
6 4401
4.3998
0.0763
Survey
3
9 457.8
2.2602
0.0600
Site(Uplift)
3
15 692
3.12
0.0270*
Uplift × Survey
5
6 881.5
1.6259
0.1407
Transect (Site(Uplift))
13
5 247.7
12.894
0.0001***
Survey × Site(Uplift)
8
4 284.5
1.3252
0.1584
Survey×Transect(Site(Uplift))
32
3 326.2
8.1729
0.0001***
Res
1 146
406.98
32 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Figure 26: Principal coordinates analysis (PCO) of distance among centroids for the six sites surveyed
between 2017 and 2020, based on a Bray-Curtis similarity matrix of community assemblage
data. Vector overlay shows taxa with > 0.6 correlation.
As in previous surveys, few mobile reef fish (excluding triplefins) were seen in 2019 and 2020 (Figure
27). The exception was at Kaikōura South, which had means of 41 and 18 fish along the transects in
2019 and 2020, respectively. The other sites had averages of fewer than 10 fish (Figure 27). Banded
wrasse (Pseudolabrus fucicola) and spotties (Notolabrus celidotus) were the most abundant fish
species. Other fish observed (in order of decreasing abundance) were blue moki (Latridopsis ciliaris),
butterfish (Odax pullus), blue cod (Parapercis colias), marblefish (Aplodactylus arctidens), and red
moki (Cheilodactylus spectabilis).
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 33
Figure 27: Average abundances of fish at each site during each survey. In each pair of bars, the left bar
refers to the northern site and the right bar to the southern site. N = 3 transects, with the
exception of second surveys at Waipapa Bay South, where n = 4. Error bars represent 1 s.e.
Transects were 50 m in length, and the area surveyed was 1 m either side of the transect, and
2 m above the transect.
Most black foot and yellow foot pāua (Haliotis iris and Haliotis australis) were recorded in about 0.5–
3.5 m (Figure 28). Numbers of both species appeared to increase at Okiwi Bay sites from 2017 to 2020.
An apparent increase in black foot pāua at Waipapa Bay after 2017 was largely driven by the addition
of a transect at Waipapa Bay South which had several pāua, but a small increase in numbers was
recorded at Waipapa North (see Figure 25). Several yellow foot pāua were observed in 2020 at Waipapa
Bay after being virtually absent between 2017- 2019. Numbers were too low to examine size structure
of populations in any detail, but pāua at Waipapa were generally over the legal size limit.
2017 2019 2020 2017 2018 2019 2020 2017 2018 2019 2020
0
10
20
30
40
50
Number
Kaikoura Okiwi Bay Waipapa Bay
34 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Figure 28: Box-whisker plots showing Haliotis iris (black foot pāua, top) and Haliotis australis (yellow foot
pāua, bottom) depth distributions at each site through time. Sample counts are at the top of
each plot.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 35
Figure 29: Box-whisker plot showing Haliotis iris (black foot pāua) size distribution at each site through
time. Sample counts are at the top of the plot. Haliotis australis (yellow foot pāua) sizes are not
shown due to their absence or low numbers. The red dashed line represents the legal harvesting
size of 125 mm.
36 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
4. DISCUSSION
This research extends the previous work done as part of the Kaikōura Earthquake Marine Recovery
Package (Alestra et al. 2019) and provides an updated assessment of the state of rocky reef systems that
underwent impacts from coastal uplift. Overall, the results of the most recent surveys show that
intertidal benthic communities are recovering only in low intertidal zone areas where abundant algal
stands have managed to survive or re-establish. However, these low-zone algal communities have
undergone significant post-earthquake shifts in species composition and are now dominated by different
suites of species compared with the pre-earthquake conditions. Long-lasting impacts on intertidal reefs
were still evident three years after the earthquake and varied across uplift levels. Subtidally, there was
only minor recovery of seaweeds in de-vegetated areas and previously abundant algal stands appear to
have become more sparse and fragmented.
4.1 Intertidal rocky reefs
The latest surveys showed that the biogenic structure of uplifted reefs is still significantly altered by the
impact of the earthquake. Under all degrees of uplift, large portions of intertidal reefs were almost
entirely devoid of algal cover, with most algae surviving only in the low intertidal. These results confirm
that much of the mid-tidal zones, which supported lush and diverse algal communities before the
earthquake (Schiel 2004, Schiel 2006), is now unsuitable for colonisation of large algae.
Hot temperatures and high erosion rates are the most likely causes underlying the lack of algal recovery
over vast areas of uplifted reefs (Schiel at al. 2018, 2019, Alestra et al. 2019). Temperature data
collected from mid-zone areas of uplifted reefs show that, in the absence of algal cover, summer
temperatures in proximity to the substratum often exceed 35 °C, with peaks well over 40 °C (Figure 29).
Despite the reefs still being submerged at high tide, such extreme low-tide temperatures are lethal to
most marine organisms, making any sign of recovery short-lived. For example, sparse recruitment of
the habitat-forming fucoid Hormosira banksii still occurs in the mid zone at some sites during the cooler
months (Figure 29), but the newly settled algae quickly burn off during summer.
Figure 29: Summer temperatures in mid-intertidal areas often exceed 35 °C (left) and result in the burn-
off of virtually all algae. On the right: patches of Hormosira banksii (within the red circles),
photographed in spring 2018 did not survive the following summer. Temperature data and
photo are from the Kaikōura North 1 site.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 37
Ongoing reef erosion, especially of large mudstone platforms, are also contributing to poor widespread
algal recovery. Hot, dry conditions (Stephenson & Kirk 1998) and absence of algal cover (Bosence
1983, Steneck 1986) are critical factors driving high erosion rates. Erosion data collected as part of our
MBIE research between 2018 and 2020 showed lower erosion rates (2.6 mm per year) in areas
experimentally maintained as shaded and moist at low tide, compared with areas lacking shade and
water at low tide (7.7 mm per year). This confirms that heat and desiccation can greatly affect the
physical structure of the uplifted reefs, in addition to the intertidal biota.
In line with the results of previous sampling, most sites in the low intertidal zone hosted abundant and
diverse algal communities. Large brown algae dominated low zone communities in areas of low uplift
(around 1 m) at Cape Campbell and around the Kaikōura Peninsula. The latest surveys showed a steady
increase in the abundance of large brown algae at most low- and medium-uplift sites, but a lack of
recovery at the Waipapa Bay sites, in the area of highest uplift. Between November 2018 and November
2019, the abundance of large brown algae also continued to increase at the control sites in the Oaro
area, where they experienced high mortality during the 2017–2018 hot summer (Alestra et al. 2019,
Thomsen et al. 2019).
Despite increasing abundances at many sites, comparisons with pre-earthquake data show that post-
earthquake assemblages of large brown algae are no longer dominated by bull kelp (Durvillaea spp.),
but with other species of fucoids (primarily Carpophyllum maschalocarpum) representing the vast
majority of large brown algae cover three years after the earthquake. Since 2017, no site showed
increasing abundances of bull kelp and there was no sign of recovery at the Waipapa Bay sites, where
bull kelp was completely extirpated. The post-earthquake distribution of bull kelp is highly patchy, with
dense stands surviving in pockets of favourable habitat, such as headlands, reef fringes, and offshore
rocks. More target aerial drone surveys are required to capture this variability and assess the state of
bull kelp forests more accurately, but the data clearly show a decline in bull kelp cover at most sites
along the transect lines. At the same time, the cover of Carpophyllum maschalocarpum and other
smaller fucoids increased almost everywhere, particularly where there was low uplift. The implications
of changing patterns of abundance of dominant canopy-formers in the low intertidal are difficult to
predict but may be profound. There are obvious morphological differences between bull kelp and other
smaller fucoids, which may not exert the same strong control on the associated communities of algae
(Taylor & Schiel 2005) and invertebrates (Smith & Simpson 1995), and may not play the same role in
nearshore food webs because they are less palatable to herbivorous fish (Taylor & Schiel 2010).
The abundance of fleshy red algae, a speciose group which accounts for the majority of the diversity in
low zone algal communities, increased in areas where large brown canopies decreased. As in previous
surveys, three years after the earthquake, red algae were more abundant in areas with medium- and
high-uplift along the northern part of the coastline than at low-uplift sites. Pre-earthquake data show
that algal communities at medium- and high-uplift sites were not dominated by fleshy red algae before
the earthquake. Fleshy reds most likely benefitted from the high earthquake mortality of large browns
and their widespread expansion reshaped low zone communities in areas with uplift greater than 1.5 m
(Figure 30).
38 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Figure 30: Widespread loss of fucoid canopies (left) was associated with the expansions of turfs of red algae
(right) where the uplift exceeded 1.5 m. This may result in reduced productivity and preclude
the return to the original state.
Shifts from fucoid canopies to turfs of red algae are usually associated with reduced community
complexity and lower productivity (Schiel & Lilley 2011, Tait & Schiel 2011, Alestra et al. 2014). Even
more importantly, the recovery of large canopy-forming algae following disturbances can be inhibited
by the proliferation of low-lying algal turfs (O’Brien & Scheibling 2018). Our regression analyses
confirmed that this may be occurring along the earthquake-affected coastline, with denser fucoid
canopies being found in the presence of sparser turfs or red algae and vice versa. Turf domination of
benthic communities adds to the impact of poor connectivity among fragmented stands of surviving
brown algae. The majority of the gametes of large fucoids disperse only a few metres away from the
source plants (Dunmore 2006) and the combination of limited propagule supply and competitive
exclusion by fleshy red algae makes the re-establishment of canopies of large brown algae unlikely
without interventions of restoration or rehabilitation. As part of the MBIE research, we are currently
attempting to re-establish populations of Durvillaea poha (the bull kelp species most affected by the
earthquake) using zygote seeding and transplants in areas of reef from which low-laying red and brown
algae were cleared.
Encrusting and turf-forming coralline algae were abundant in the low zone at most sites independently
of the degree of uplift, with percentage covers generally above 30%. These species play an important
role in the life cycle of many taonga invertebrates, for example, inducing the settlement of pāua larvae
(Morse & Morse 1984), and acting as nurseries for juvenile cat’s eye snails (Robinson 1992). Patterns
of abundance of limpets across all intertidal zones were also unrelated to the degree of uplift and highly
variable across sites. Despite limpets experiencing high mortality in the immediate aftermath of the
coastal uplift, the earthquake does not seem to have left a long-lasting legacy on their abundances.
Unlike large habitat-forming brown algae, connectivity among surviving limpet populations was likely
maintained because they are broadcast spawners with considerable larval dispersal, which facilitates
faster recovery.
Despite some consistency between the most recent results and those of previous surveys, the long-term
future of these intertidal communities remains problematic because of ongoing changes in the physical
environment, which is contributing to delays in the recovery process. In particular, over the last 24
months, significant changes in patterns of gravel accumulation were seen in the Waipapa Bay and Ward
areas, with gravel building up in the low intertidal zone, the area of greatest post-earthquake diversity,
and even inundating entire sites (Figure 31). It remains to be seen whether these physical processes of
erosion and sedimentation will settle down and allow greater recovery of reef biota.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 39
Figure 31: Widespread gravel inundation was observed in some areas with medium and high uplift (on the
left, Waipapa Bay). The low intertidal zone is often the first area to infill with gravel,
threatening the persistence of post-earthquake algal communities. For example, bull kelp plants
smothered by gravel are a common occurrence at Ward (right).
4.2 Subtidal rocky reefs
Previous subtidal surveys in 2017 and 2018 showed significant effects of the earthquake on shallow
subtidal communities at sites with high uplift (Waipapa Bay), and minor effects at sites with medium
uplift (Ward and Okiwi Bay). The most obvious effects were on the abundances of understorey algae
(encrusting and turfing coralline algae, and red and brown encrusting algae), large brown algae
(laminarian and fucoid algae such as Lessonia variegata, Marginariella boryana, Landsburgia
quercifolia), and the emergence of bare rock at some sites (Alestra et al. 2019).
The 2019 and 2020 surveys, 2.5 and 3.5 years after the earthquake respectively, showed minor recovery
of seaweeds and invertebrates at Waipapa Bay. In particular, there were increases in encrusting red
algae and corallines, and recruitment of red and brown foliose algae. Sessile invertebrates such as
sponges and ascidians also increased in cover. Despite this recovery, extensive areas of bare rock were
still present. The most striking difference compared with previous surveys was the decrease in large
brown algae at some Kaikōura Peninsula and Okiwi Bay sites. This decline has also been observed at
other sites included in the original Kaikōura Earthquake Marine Recovery Package (Alestra et al. 2019),
which were recently re-sampled as part of the MBIE research. Reasons for this decline are unclear, but
it may be due to a combination of altered wave dynamics because of the uplift, extreme wave events,
marine heatwaves, and/or scour due to movement of cobble, gravel, or sand substrates.
There were shifts in sand/gravel distribution at Waipapa Bay and Okiwi Bay South. The shifts in sand
and gravel can scour rock surfaces, slowing recovery of these habitats, and are indicative of a very
dynamic physical environment. In addition, the reduced propagule supply of large brown algae at
Waipapa Bay could reduce the amount of recruitment. Recruits of large brown algae have been
recorded, but only of some species (Landsburgia quercifolia and Carpophyllum maschalocarpum).
These recruits were very small and therefore did not contribute to changes in the cover of large brown
algae. As part of the MBIE research, large brown algae collected from unaffected locations are being
transplanted to facilitate the recovery of large brown algae at Waipapa Bay.
40 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
4.3 Conclusions
The surveys presented in this report provide an updated assessment of the state of nearshore reef
communities along the uplifted coastline. This work augments an extensive body of information that
had never been previously available for this region. Extended post-earthquake monitoring of rocky reef
habitats is extremely valuable given that the uplifted coastline is still in a transient state of recovery, in
a very dynamic physical environment. In addition, post-earthquake recovery and resulting management
implications are of great interest and concern among the various coastline user groups, including
customary and recreational harvesters, commercial fishers, tourist operators, citizens’ groups, tangata
whenua, and local residents. Longer time series will allow a better assessment of recovery trajectories
and will be helpful to characterise the impacts of other local (e.g., floods, sedimentation, and pedestrian
and vehicle traffic) and global stressors (e.g., heatwaves) on the recovery of some equilibrium of the
post-earthquake ecosystem. Finally, this work provides an important spatial and temporal context for
experimental studies and for important management decisions, particularly regarding a range of human
uses and the re-opening of the pāua fishery.
5. ACKNOWLEDGMENTS
We thank the Ministry for Primary Industries/Fisheries New Zealand, and especially Rich Ford, for
funding this research under project KAI2016-05 and helping along the way, and the University of
Canterbury for continued support.
We thank John Pirker, Sharyn Goldstien, and Jason Rurawai for help with community liaison around
Kaikōura. Many thanks, in particular, to Te Rūnanga o Kaikōura, Te Korowai o Te Tai ō Marokura,
and the Kaikōura Coastal Marine Guardians for advice and supporting our research.
Many thanks also to Kate Clark (GNS) and Dr Shane Orchard for providing site-specific uplift data and
to Dr Paul South (Cawthron Institute) for helping with species identifications.
Thanks to divers from the Cawthron Institute and Marlborough Commercial Diving Services Ltd.
(James Brodie, Mark Hodren, Luke Ogilvy, Craig Honeybone, and Lee McFetrish). Many thanks for
boat launching access to John, Jak, and Ash Reader, Tonya Patchett, and Ted Howard.
6. REFERENCES
Alestra, T.; Gerrity, S.; Dunmore, R.A.; Marsden, I.D.; Pirker, J.G.; Schiel, D.R. (2019). Rocky reef
impacts of the Kaikōura earthquake: quantification and monitoring of nearshore habitats
and communities. New Zealand Aquatic Environment and Biodiversity Report No. 212.
120 p.
Alestra, T.; Gerrity S.; Dunmore R.A.; Schiel, D.R. (2020). Rocky reef impacts of the Kaikōura
earthquake: extended monitoring of nearshore habitats and communities Year 1 results.
Prepared for the Ministry for Primary Industries. New Zealand Fisheries Assessment Report
2020/01. 40 p.
Alestra, T.; Tait, L.W.; Schiel, D.R. (2014). Effects of algal turfs and sediment accumulation on
replenishment and primary productivity of fucoid assemblages. Marine Ecology Progress
Series 511: 59–70.
Anderson, M.J.; Gorley, R.N.; Clarke, R.K. (2008) PERMANOVA+ for PRIMER: Guide to software
and statistical methods. Bretonside Copy, Plymouth, UK
Barrientos, S.E.; Ward, S.N. (1990). The 1960 Chile earthquake: inversion for slip distribution from
surface deformation. Geophysics Journal International 103: 589–598.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 41
Bosence, D.W.J. (1983). Coralline algal reef frameworks. Journal of the Geological Society 140: 365–
376.
Castilla, J.C. (1988). Earthquake-caused coastal uplift and its effects on rocky intertidal kelp
communities. Science 242(4877): 440–443.
Castilla, J.C.; Manríquez, P.H.; Camaño, A. (2010). Effects of rocky shore coseismic uplift and the
2010 Chilean mega-earthquake on intertidal biomarker species. Marine Ecology Progress
Series 418: 17–23.
Castilla, J.C.; Oliva, D. (1990). Ecological consequences of coseismic uplift on the intertidal kelp belts
of Lessonia nigrescens in central Chile. Estuarine, Coastal and Shelf Science 31(1): 45–56.
Clark, K.J.; Nissen, E.K.; Howarth, J.D.; Hamling, I.J.; Mountjoy, J.J.; Ries, W.F.; Jones, K.J.;
Goldstien, S.; Cochran, U.A.; Villamor, P.; Hreinsdóttir, S.; Litchfield, N.J.; Mueller, C.;
Berryman, K.R.; Strong, D.T. (2017). Highly variable coastal deformation in the 2016
Mw7.8 Kaikōura earthquake reflects rupture complexity along a transpressional plate
boundary. Earth and Planetary Science Letters 474: 334–344.
Clarke, K.R.; Warwick, R.M. (2001) Change in marine communities: An approach to statistical analysis
and interpretation (2nd edition). PRIMER-E Ltd., Plymouth, UK
Dunmore, R.A. (2006). Demography of early life stages of habitat-forming intertidal fucoid algae. PhD
dissertation, University of Canterbury, New Zealand.
Gerrity, S.; Alestra, T.; Fishman, H.S.; Schiel, D.R. (2020). Earthquake effects on abalone habitats and
populations in southern New Zealand. Marine Ecology Progress Series 656: 153–161. DOI:
https://doi.org/10.3354/meps13458
Hamling, I.J.; Hreinsdóttir, S.; Clark, K.; Elliott, J.; Liang, C.; Fielding, E.; Wright, T.J. (2017).
Complex multifault rupture during the 2016 Mw7.8 Kaikōura earthquake, New Zealand.
Science 356: eaam7194.
Jaramillo, E.; Dugan, J.E.; Hubbard, D.M.; Melnick, D.; Manzano, M.; Duarte, C.; Campos, C.;
Sanchez, R. (2012). Ecological implications of extreme events: footprints of the 2010
earthquake along the Chilean coast. PloS One 7(5): e35348.
Lilley, S.A.; Schiel, D.R (2006). Community effects following the deletion of a habitat-forming alga
from rocky marine shores. Oecologia 148 (4): 672681.
Morse, A.N.; Morse, D.E. (1984). Recruitment and metamorphosis of Haliotis larvae induced by
molecules uniquely available at the surfaces of crustose red algae. Journal of Experimental
Marine Biology and Ecology 75: 191–215.
O'Brien, J.M.; Scheibling, R.E. (2018). Turf wars: competition between foundation and turf-forming
species on temperate and tropical reefs and its role in regime shifts. Marine Ecology
Progress Series 590: 1–17.
Robinson, L.J. (1992). Population and reproductive ecology of Turbo smaragdus in the Kaikōura
region. MSc dissertation, University of Canterbury, New Zealand.
Schiel, D.R. (2004). The structure and replenishment of rocky shore intertidal communities and
biogeographic comparisons. Journal of Experimental Marine Biology and Ecology 300:
309–342.
Schiel, D.R. (2006). Rivets or bolts? When single species count in the function of temperate rocky reef
communities. Journal of Experimental Marine Biology and Ecology 338: 233–252.
Schiel, D.R.; Alestra, T.; Gerrity, S.; Orchard, S.; Dunmore, R.A.; Pirker, J.G.; Lilley, S.A.; Tait,
L.W.; Thomsen, M.S. (2019). The Kaikōura earthquake in southern New Zealand: loss of
connectivity of marine communities and the necessity of a cross-ecosystems perspective.
Aquatic Conservation: Marine and Freshwater Ecosystems 29 (9): 1520–1534.
Schiel, D.R.; Gerrity, S.; Alestra, T.; Pirker, J.G.; Marsden, I.D.; Dunmore, R. A.; Tait, L.W.; South,
P.M.; Taylor, D.I.; Thomsen, M.S. (2018). Kaikōura earthquake: Summary of impacts and
changes in nearshore marine communities. In: Shaky Shores Coastal impacts & responses
to the 2016 Kaikōura earthquakes. New Zealand Coastal Society, Special Publication 3.
44 p.
42 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Schiel, D.R.; Lilley, S.A. (2011). Impacts and negative feedbacks in community recovery over eight
years following removal of habitat-forming macroalgae. Journal of Experimental Marine
Biology and Ecology 407: 108–115.
Schiel, D.R.; Lilley, S.A.; South, P.M. (2018). Ecological tipping points for an invasive kelp in rocky
reef algal communities. Marine Ecology Progress Series 587: 93–104.
Smith, S.D.A; Simpson, R.D. (1995). Effects of the 'Nella Dan'oil spill on the fauna of Durvillaea
antarctica holdfasts. Marine Ecology Progress Series 121: 73–89.
Steneck, R.S. (1986). The ecology of coralline algal crusts: convergent patterns and adaptive strategies.
Annual Review of Ecology and Systematics 17: 273–303.
Stephenson, W.J.; Kirk, R.M. (1998). Rates and patterns of erosion on intertidal shore platforms,
Kaikōura Peninsula, South Island, New Zealand. Earth Surface Processes and Landforms:
The Journal of the British Geomorphological Group 23: 1071–1085.
Tait, L.W.; Schiel, D.R. (2011). Legacy effects of canopy disturbance on ecosystem functioning in
macroalgal assemblages. PLOS ONE 6: e26986
Taylor, D.I.; Schiel, D.R. (2005). Self-replacement and community modification by the southern bull
kelp Durvillaea antarctica. Marine Ecology Progress Series 288: 87–102.
Taylor, D.I.; Schiel, D.R. (2010). Algal populations controlled by fish herbivory across a wave exposure
gradient on southern temperate shores. Ecology 91: 201–211
Thomsen, M.S.; Metcalfe, I.; Siciliano, A.; South, P.M.; Gerrity, S.; Alestra, T.; Schiel, D.R. (2020).
Earthquake-driven destruction of an intertidal habitat cascade. Aquatic Botany 164: 103217.
Thomsen, M.S.; Mondardini, L.; Alestra, T.; Gerrity, S.; Tait, L.W.; South, P.M.; Lilley, S.A.; Schiel,
D.R. (2019). Local extinction of bull kelp (Durvillaea spp.) due to a marine heatwave.
Frontiers in Marine Science 6:84.
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 43
7. APPENDICES
Appendix 1: Subtidal site details with degree of uplift, location, maximum and average depth, visibility, and number of quadrats used in analyses for
each survey time.
Site
Transect
Uplift
Transect start
Transect end
Max.
depth
(m)
Ave.
depth
(m)
Visibility
(m)
2017 2018
Number of quadrats used in
analyses (50% rock)
2017 2018 2019 2020
Kaikōura North Rahui
T1
L
-42.4155
173.7089
-42.4153
173.7093
7.0
5.3
5
15
14
19
T2
L
-42.413
173.7073
-42.4134
173.7072
7.0
4.5
5
20
20
20
T3
L
-42.4135
173.7063
-42.4132
173.7065
5.7
2.0
5
20
20
20
Kaikōura South S2
T1
L
-42.4355
173.6921
-42.4356
173.6926
4.6
2.6
5
20
20
20
T2
L
-42.4352
173.6929
-42.4351
173.6926
6.8
4.1
5
20
20
20
T3
L
-42.4347
173.6926
-42.435
173.6931
7.3
5.6
5
19
20
20
Okiwi Bay North
T1
M
-42.2171
173.8726
-42.5209
173.509
5.5
3.9
1-2
1.5
20
20
20
20
T2
M
-42.2178
173.8717
-42.218
173.872
4.2
2.4
4
2
20
20
20
20
T3
M
-42.2181
173.8716
-42.2183
173.872
5.4
2.9
4
2
20
20
20
20
Okiwi Bay South
T1
M
-42.2189
173.8665
-42.2194
173.8665
4.1
2.1
1
18
20
20
20
T2
M
-42.2189
173.869
-42.219
173.8696
3.8
2.2
1
2
12
19
17
20
T3
M
-42.2191
173.8697
-42.2194
173.8701
5.4
3.3
5
2.5
19
20
20
20
Waipapa Bay North
T1
H
-42.2044
173.8794
-42.2045
173.8798
4.5
3.5
1-1.5
2.5
18
20
19
19
T2
H
-42.205
173.8798
-42.205
173.8803
5.5
4.4
1.5
2.5
18
20
18
13
T3
H
-42.2056
173.8796
-42.2057
173.8802
6.1
5.3
1.5-2.5
2.5
17
12
18
20
Waipapa Bay South
T1
H
-42.2092
173.8758
-42.2097
173.8758
2.8
1.7
0.5
0.5
6
5
T2
H
-42.2099
173.8762
-42.2103
173.8763
3.8
2.9
0.5
0.5
8
20
20
20
T3
H
-42.2096
173.8774
-42.21
173.8778
4.9
3.6
2
1.5
11
14
7
20
T1b
H
20
19
19
44 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
Appendix 2: Results of SIMPER tests for each pair of uplift groups with significantly different
benthic community composition in the post-earthquake high (A), mid (B) and low zone (C) in
November 2019. For each test, the taxa contributing to up to 90% of the dissimilarity between
groups are listed.
A) Post-earthquake high zone
Control vs Medium uplift - Average dissimilarity = 91.98
Taxa Average
abundance
Control
Average
abundance
Low-uplift
Average
dissimilarity Contribution
%
Cumulative
contribution
%
Ulva spp.
25.06
0.13
37.22
40.47
40.47
Chamaesipho columna
2.12
0.07
13.99
15.21
55.68
Pyropia spp.
1.85
0.3
12.49
13.58
69.25
Enteromorpha spp.
3.27
0.04
5.73
6.23
75.48
Coralline turf
0.51
0
4.28
4.65
80.13
Limnoperna pulex
0.25
0.11
3.49
3.79
83.93
Tube-forming polychaetes
0.11
0
3.12
3.4
87.32
Encrusting algae
0.12
0.02
2.36
2.56
89.88
Mytilus galloprovincialis
0.3
0.04
2.01
2.18
92.07
Low uplift vs Medium uplift - Average dissimilarity = 96.31
Taxa Average
abundance
Control
Average
abundance
Medium-
uplift
Average
dissimilarity Contribution
%
Cumulative
contribution
%
Pyropia spp.
7.55
0.3
44.07
45.76
45.76
Limnoperna pulex
0.01
0.11
10.58
10.98
56.74
Ulva spp.
0.29
0.13
7.98
8.29
65.03
Chamaesipho columna
0.05
0.07
6.93
7.2
72.23
Encrusting algae
0.21
0.02
4.9
5.09
77.31
Mytilus galloprovincialis
0
0.04
3.92
4.07
81.38
Scytosiphon lomentaria
0.22
0
3.25
3.38
84.76
Enteromorpha spp.
0.59
0.04
3.15
3.27
88.02
Aulacomya maoriana
0
0.03
2.1
2.18
90.21
Fisheries New Zealand Kaikōura earthquake - rocky reef impacts 45
B) Post-earthquake mid zone
Control vs Low uplift - Average dissimilarity = 96.05
Taxa Average
abundance
Control
Average
abundance
Low-uplift
Average
dissimilarity Contributio
n %
Cumulative
contribution
%
Gelidium caulacantheum
0.05
16.15
12.77
13.29
52.61
Hormosira banksii
0.28
14.06
10.24
10.66
63.27
Ulva spp.
1.44
10.8
8.36
8.7
71.97
Encrusting coralline algae
2.17
6.92
5.89
6.13
78.1
Encrusting algae
5.5
0.1
3.59
3.73
81.84
Cystophora scalaris
0
1.61
1.6
1.66
83.5
Echinothamnion hystrix
0
1.96
1.53
1.59
85.09
Sarcothalia lanceata
0
2.44
1.49
1.55
86.65
Champia novae-zelandiae
0
1.7
1.2
1.25
87.9
Pyropia spp.
1.41
0
1.08
1.12
89.02
Enteromorpha spp.
1.19
0.01
0.88
0.92
89.94
Colpomenia bullosa
0.18
0.93
0.8
0.83
90.76
Control vs Medium uplift - Average dissimilarity = 91.05
Taxa Average
abundance
Control
Average
abundance
Medium-
uplift
Average
dissimilarity Contributio
n %
Cumulative
contribution
%
Articulated coralline algae
49.8
0.82
37.02
40.66
40.66
Gelidium caulacantheum
16.15
1.82
12.05
13.24
53.9
Ulva spp.
10.8
9.08
10.38
11.4
65.3
Hormosira banksii
14.06
0
10.31
11.32
76.63
Encrusting coralline algae
6.92
1.04
5.18
5.68
82.31
Cystophora scalaris
1.61
0
1.58
1.73
84.05
Echinothamnion hystrix
1.96
0.22
1.54
1.69
85.73
Sarcothalia lanceata
2.44
0
1.48
1.62
87.36
Champia novae-zelandiae
1.7
0
1.19
1.31
88.67
Polysiphonia spp.
0.81
0.55
0.88
0.97
89.64
Colpomenia bullosa
0.93
0
0.78
0.86
90.49
46 Kaikoura earthquake rocky reef impacts Fisheries New Zealand
C) Post-earthquake low zone
Low uplift vs Medium uplift - Average dissimilarity = 66.89
Taxa Average
abundance
Control
Average
abundance
Low-uplift
Average
dissimilarity Contribution
%
Cumulative
contribution
%
Carpophyllum maschalocarpum
38.43
14.79
10.33
15.44
15.44
Encrusting coralline algae
33.53
40.12
9.22
13.78
29.22
Articulated coralline algae
12.97
10.75
4.48
6.7
35.93
Encrusting algae
11.88
4.13
4.07
6.08
42.01
Echinothamnion hystrix
3.22
8.43
3.26
4.88
46.89
Marginariella boryana
3.73
7.2
2.94
4.4
51.29
Durvillaea willana
3.75
5.03
2.6
3.89
55.18
Streblocladia muelleriana
0.34
8.13
2.52
3.76
58.94
Durvillaea poha
3.93
3.56
2.36
3.53
62.47
Ulva spp.
3.03
5.43
2.15
3.22
65.69
Pterocladia lucida
0.68
6.84
2.13
3.19
68.88
Cystophora scalaris
4.68
1.09
2
3
71.87
Ectocarpus spp.
1.18
4.27
1.8
2.69
74.56
Lessonia variegata
2.08
3.75
1.63
2.43
76.99
Gelidium microphyllum
3.73
1.48
1.49
2.23
79.22
Chondria macrocarpa
1.25
3.95
1.42
2.13
81.35
Filamentous red algae
1.31
3.7
1.41
2.1
83.46
Polysiphonia spp.
2.64
1.11
1.15
1.72
85.18
Halopteris sp.
2.98
1.36
1.11
1.67
86.85
Dictyota spp.
2.29
0.64
0.83
1.24
88.09
Sarcothalia lanceata
0.07
2.65
0.82
1.22
89.31
Glossophora kunthii
1.73
0.69
0.67
0.99
90.31
Low-uplift vs High-uplift - Average dissimilarity = 81.9
Taxa
Average
abundance
- Low-
uplift
Average
abundance -
High-uplift
Average
dissimilarity Contribution
%
Cumulative
contribution
%
Carpophyllum maschalocarpum
38.43
6.51
15.76
19.24
19.24
Encrustng coralline algae
33.53
21.67
12.92
15.78
35.02
Streblocladia muelleriana
0.34
18.47
6.54
7.99
43.01
Articulated coralline algae
12.97
0
6.03
7.37
50.37
Encrusting algae
11.88
1.44
5.55
6.77
57.14
Echinothamnion hystrix
3.22
11.7
4.79
5.84
62.99
Chondria macrocarpa
1.25
9.73
3.74
4.56
67.55
Cystophora scalaris
4.68
0
2.7
3.29
70.84
Ulva spp.
3.03
3.87
2.36
2.89
73.73
Filamentous red algae
1.31
4.9
2.06
2.52
76.25
Durvillaea willana
3.75
0
1.69
2.06
78.31
Marginariella boryana
3.73
0
1.68
2.05
80.35
Gelidium microphyllum
3.73
0
1.65
2.02
82.37
Durvillaea poha
3.93
0
1.55
1.9
84.27
Halopteris sp.
2.98
0.31
1.53
1.87
86.13
Polysiphonia spp.
2.64
0
1.28
1.57
87.7
Glossophora kunthii
1.73
1.95
1.21
1.48
89.18
Dictyota spp.
2.29
0.25
1.09
1.33
90.52
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
Detailed research has documented gradual changes to biological communities attributed to increases in global average temperatures. However, localized and abrupt temperature anomalies associated with heatwaves may cause more rapid biological changes. We analyzed temperature data from the South Island of New Zealand and investigated whether the hot summer of 2017/18 affected species of bull kelp, Durvillaea antarctica, D. poha, and D. willana. Durvillaea spp. are large iconic seaweeds that inhabit the low intertidal zone of exposed coastlines, where they underpin biodiversity and ecosystem functioning. Sea surface temperatures (SST) during the summer of 2017/18 included the strongest marine heatwaves recorded in 38 years of existing oceanic satellite data for this region. Air temperatures were also high, and, coupled with small wave heights, resulted in strong desiccation stress during daytime low tides. Before-After analysis of drone images of four reef platforms (42, 42, 44, and 45°S) was used to evaluate changes to bull kelp over the hot summer. Bull kelp loss varied among species and reefs, with the greatest (100%) loss of D. poha at Pile Bay in Lyttelton Harbor (44°S). In Pile Bay, SST exceeded 23°C and air temperatures exceeded 30°C, while Durvillaea was exposed for up to 3 h per day during low tide. Follow-up surveys showed that all bull kelps were eliminated from Pile Bay, and from all reefs within and immediately outside of Lyttelton Harbor. Following the localized extinction of bull kelp in Pile Bay, the invasive kelp Undaria pinnatifida recruited in high densities (average of 120 m-2). We conclude that bull kelps are likely to experience additional mortalities in the future because heatwaves are predicted to increase in magnitude and durations. Losses of the endemic D. poha are particularly concerning due to its narrow distributional range.
Technical Report
Full-text available
Surveys along 130 km of coastline in the first sixteen months following the Kaikōura earthquake showed significant damage to intertidal benthic communities at all sites. Subtidal communities were impacted only at sites with uplift greater than 2 m. Taonga species such as paua and bull kelp were still present at most sites and showing signs of post-earthquake recruitment. This information provides a key baseline for management decisions and new research into long-term trajectories of recovery.
Article
Full-text available
The devastating earthquake (moment magnitude: 8.8 MW) that struck Chile on 27 February 2010 and the following tsunami waves produced widespread damage, coastal coseismic uplifts, and large-scale mortality of rocky intertidal and shallow subtidal organisms. The effects were particularly remarkable around the Gulf of Arauco, Santa Mar a Island and the Bay of Concepcion (similar to 36 to 38 degrees S). Measurements of rocky intertidal and shallow subtidal belt-forming (biomarker) species conducted a few weeks after the earthquake indicated coastal uplifts ranging from similar to 0.2 to 3.1 m, which are similar to uplifts estimated by FitzRoy (1839; Voyages of the Adventure and Beagle, Vol. II) and Darwin (1839; Voyages of the Adventure and Beagle, Vol. III) after the 1835 Chilean earthquake. In major uplifted sites, there was massive mortality of the main intertidal and shallow subtidal belt-forming species, such as lithothamnioid melobesioid coralline algae, brown kelps and mussels, and dramatic changes in the marine rocky intertidal ecosystem. We suggest that in the southeastern Pacific, drastic and rapid coastal deformations seriously impinge on rocky shore populations, communities and ecosystems and may have significance for management and conservation practices, as for example in connection with alterations of parental stocks and recruitment rates.
Article
The 2016 Mw7.8 Kaikōura earthquake lifted 140km of coastline on New Zealand’s South Island by up to 6.4m. This caused extensive mortality and destruction of habitat critical for early life stages of blackfoot abalone, Haliotis iris (called pāua), a species of cultural and commercial importance. The fishery for pāua was closed, at considerable financial loss to local communities. This study determined the extent to which habitats and populations of pāua survived along the coastline. With aerial imaging, the coast was categorised into broad habitats at a 10m scale. This was used to select areas for in situ assessments of pāua populations and specific habitat features at 26 sites over 1.5 years. We quantified key habitat features to identify correlates and potential drivers of pāua abundance and distribution. We found that despite extensive habitat degradation from uplift, erosion and sedimentation, abundant pāua in size classes <30mm shell length indicated successful settlement and juvenile recruitment had occurred soon after the earthquake. Pāua up to 170mm shell length had also survived in shallow habitats. A generalized linear mixed model showed that pāua were negatively influenced by the degree of uplift, and positively associated with the cover of unconsolidated layered rocks. Juvenile pāua (<85mm) abundance was greatest at sites with <2.5m of uplift. There was further recruitment 1.5 years post-earthquake and evidence of good growth of the previous year’s cohort. Despite major disruption to this coastline, there appears to be very good potential for recovery of pāua and the fishery.
Article
Large scale disturbances associated with anthropogenic activities or natural disasters can destroy primary habitat-forming species like corals, seagrasses and seaweeds. However, little research has documented if and on how large-scale disturbances affect secondary habitat formers, such as epiphytes and small animals that depend on biogenic habitats. Here we quantified changes in the abundance of both primary and secondary habitat-forming seaweeds as well as seaweed-associated invertebrates before and after a 7.8 Mw earthquake that uplifted four intertidal reef platforms by 0.5-0.8 m on the Kaikōura coastline in New Zealand. We found that the dominant primary (Hormosira banksii and three Cystophora species) and secondary (obligate and facultative epiphytes) habitat-forming seaweeds were all decimated and that mobile seaweed-associated animals were significantly less abundant (per gram of seaweed biomass) after the earthquake. Importantly, epiphytes became functionally extinct after the earthquake, as less than 0.1% of the populations survived, whereas primary habitat formers survived in suitable microhabitats, like water covered tide-pools and tidal channels. Based on these results we also discuss possible cascading ecosystem effects and future scenarios for natural recovery vs. active restoration that could speed up the recovery of habitat-forming species on degraded reefs.
Article
• The Mw 7.8 earthquake that struck the north‐east coast of the South Island of New Zealand in November 2016 caused extensive upheaval, of up to 6 m, over 110 km of coastline. Intertidal habitats were greatly affected with extensive die‐off of algal communities, high mortalities of benthic invertebrates, and greatly reduced ecosystem functioning, such as primary productivity. Only isolated pockets of key species remained in these areas, many of which were within protected areas around Kaikōura. • The loss of key species of algae and invertebrates fragmented marine populations and compromised connectivity and recovery processes because of the large dispersal distances needed to replenish populations. Severe sedimentation from terrestrial slips and erosion of newly exposed sedimentary rock compromised settlement and recruitment processes of marine species at many sites, even if distant propagules should arrive. • The combination of habitat disruption, loss of species and their functioning, and impacts on commercial fisheries, especially of abalone (Haliotis iris), requires multiple perspectives on recovery dynamics. • This paper describes these effects and discusses implications for the recovery of coastal ecosystems that include the essential involvement of mana whenua (indigenous Māori people), fishers, and the wider community, which suffered concomitant economic, recreational, and cultural impacts. These community perspectives will underpin the protection of surviving remnants of intertidal marine populations, the potential use of restoration techniques, and ultimately a successful socio‐ecological recovery.
Article
Shifts in competitive balance between key functional groups may drive regime shifts in tropical and temperate marine ecosystems. On shallow reefs, regime shifts increasingly involve changes from spatial dominance by foundation species (e.g. reefbuilding corals, canopy-forming algae) to dominance by turf-forming algae differing in structural complexity. To disentangle competitive inter actions fromother processes that may contribute to these shifts, we conducted a global meta-analysis of manipulative competition experiments between foundation and turf-forming species. Canopy- forming algae had consistently negative effects on abundance of turfforming algae, particularly on subtidal reefs, but with a tendency towards larger effects on delicate filamentous forms compared to articulated coralline and corticated/coarsely branching turf. Competitive effects of turf-forming algae on canopy species were limited to early life-history stages, and similarly varied between turf functional groups and between subtidal and intertidal reefs. Conversely, shorter filamentous turf assemblages typical of tropical reefs had no significant effect on settlement and survival of coral larvae. Interactions between turf-forming algae and established coral colonies were negative overall, but variable in magnitude. Mean effect sizes indicated that corals suppress turf abundance, but not vice versa. However, turf-forming algae significantly im - pacted coral growth and tissue mortality. We suggest reefs with extensive cover of foundation species are resistant to proliferation of turf algae, but competition will inhibit recovery of reefs following disturbances that enable turf algae to establish. Therefore, competitive effects of foundation and turf-forming species must be accounted for to effectively evaluate the stability of these undesirable regime shifts and recovery potential under alternative climate and management scenarios.
Article
Invasive species are affecting coastal ecosystems worldwide and there are many potential mechanisms that allow their spread into native communities. To investigate this phenomenon, we used an experiment in which the canopy of the southern bull kelp Durvillaea antarctica was removed in 2 seasons and community development was followed over 3 yr. The invasive kelp Undaria pinnatifida recruited almost exclusively into plots from which the natural canopy had been removed. We examined, through a series of regression tree models and change point analyses, the gradients of community responses that allowed the successful recruitment of this invasive species. Analyses revealed a range of coinciding conditions, especially a decline in fucoid cover below 20% and an increase in turf cover above 80%, that facilitated Undaria recruitment. The abundance of molluscan grazers and cover of subcanopy algae had lesser effects on Undaria recruitment. In an ecological sense, there was a clear tipping point in the interaction between canopy loss and the subsequent expansion of coralline turf that allowed communities to switch from dominance by native species to seasonal dominance of Undaria. This study illustrates the complex nature of disturbance thresholds and interactions within the native communities that can facilitate the spread and recruitment success of Undaria.
Article
An earthquake with a dozen faults The 2016 moment magnitude ( M w ) 7.8 Kaikōura earthquake was one of the largest ever to hit New Zealand. Hamling et al. show with a new slip model that it was an incredibly complex event. Unlike most earthquakes, multiple faults ruptured to generate the ground shaking. A remarkable 12 faults ruptured overall, with the rupture jumping between faults located up to 15 km away from each other. The earthquake should motivate rethinking of certain seismic hazard models, which do not presently allow for this unusual complex rupture pattern. Science , this issue p. eaam7194
Article
As a result of anthropogenic habitat degradation worldwide, coastal ecosystems are increasingly dominated by low-lying, turf-forming species, which proliferate at the expense of complex biogenic habitats such as kelp and fucoid canopies. This results in dramatic alterations to the structure of the associated communities and large reductions in primary productivity. The persistence of turf-dominated systems has been attributed to the impacts of the turfs on the recovery of algal canopies and also to the different susceptibility of canopy- and turf-forming algae to altered physical conditions, in particular increased sedimentation. Here we tested the impacts of turfing geniculate coralline algae and sediment on fucoid recovery dynamics and their influence on assemblage net primary productivity (NPP). The recruitment of the habitat-forming fucoid Hormosira banksii on bare substrata was significantly higher than in treatments in which sediments, coralline turfs or turf mimics covered the substratum, indicating that sediment deposition and space pre-emption by algal turfs can synergistically affect the development of fucoid beds. NPP of coralline turfs was much lower than that of fucoid-coralline assemblages, which included a H. banksii canopy, and was reduced further by sediment accumulation. When devoid of sediment, however, coralline algae contributed to enhance fucoid-coralline assemblage NPP, because of synergistic interactions among the components of the multi-layered assemblage in optimizing light use. Our findings amplify extensive research addressing the global loss of macroalgal canopies and highlight key processes involving sediment accumulation in the benthic environment and effects on the replenishment and productivity of fucoid stands.