Volume 16, Issue 2 (2021)
published June 2021
Contents | |
Research articles |
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Paola Parretti, Macarena Ros, Ignacio Gestoso, Patrício Ramalhosa, Ana Cristina Costa and João Canning-Clode
Assessing biotic interactions between a non-indigenous amphipod and its congener in a future climate change scenario
(pp 186–207)
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To evaluate the impact of successful invasions of marine ecosystems by non-indigenous species (NIS) in a future climate change scenario, we analysed how
an increase in temperature may affect biotic interactions between resident species and newcomers. In this context, we examined the effect of temperature
on interference competition (i.e. displacement) between two ecologically-similar caprellid species that co-occur in the Portuguese Atlantic archipelago
of Madeira: the NIS Caprella scaura (Templeton, 1836) and its congener Caprella equilibra (Say, 1818). Mesocosm experiments were used
to assess the interaction between the two species and the effects of warmer ocean waters on this interaction. Specifically, we investigated the effect
of an increase in temperature on: i) survivorship and intraspecific displacement of the NIS C. scaura, ii) survivorship and interspecific displacement
when this NIS and its congener C. equilibra coexisted at similar densities, and iii) survivorship and interspecific displacement in the two species
when the density of NIS is higher compared to its congener. Furthermore, we explored differences in the heart rate of the two species as proxy
for physiological condition. Our results showed that in a future scenario of ocean warming for Madeira Island (29 °C), survivorship and intraspecific
displacement of C. scaura most likely will not be affected. The survivorship of the congener C. equilibra will not be compromised,
but its displacement will be affected by a combination of temperature and density of NIS. Overall, our results showed that warming exacerbates interspecific
interactions between the two caprellid species suggesting that climate change can modify species distribution among habitats, potentially affecting community
structure and diversity. The results of this study highlight the importance of biotic interactions and environmental context to predict and assess
NIS success and potential impacts on resident species in the perspective of climate change. |
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Dale R. Calder, James T. Carlton, Inti Keith, Kristen Larson, Linda McCann, Jonathan Geller, Melinda Wheelock, Henry H.C. Choong and Gregory M. Ruiz
Additions to the hydroids (Cnidaria, Hydrozoa) of marine fouling communities on the mainland of Ecuador and in the Galapagos Islands
(pp 208–252)
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Hydroids were examined from surveys of marine fouling communities undertaken during 2018 in Ecuador. Specimens were collected on settlement panels
in harbours at Salinas and La Libertad on the mainland, and at Isla San Cristóbal in the Galapagos Islands. Of 27 species in the samples, 18 were present
in collections from the mainland and 14 from San Cristóbal. Most frequent in samples from the mainland were Bougainvillia cf. muscus
(20 samples), Obelia microtheca (20), Clytia delicatula (19) and Pennaria disticha (10). In collections from San Cristóbal, most
frequent were Obelia alternata (27), Bougainvillia cf. muscus (16), Ectopleura crocea (13) and Cirrholovenia tetranema (11).
Based on genetic evidence, Ectopleura media Fraser, 1948 is assigned to the synonymy of E. crocea (L. Agassiz, 1862). In addition, a COI reference
sequence is deposited for the first time for Tridentata turbinata. Male gonophores of Eudendrium breve, previously unknown, were discovered
and illustrated. The cnidome of the species comprises small and large microbasic euryteles. Five of the species have not been reported before from the Tropical
Eastern Pacific. Of these, three (Amphinema cf. rugosum, Egmundella humilis, and Campanulinida, undetermined) were found only in the Galapagos,
one (Clytia delicatula) occurred at both mainland sites and the Galapagos, and one (Opercularella sp.) was collected only from a station on the mainland.
Six other species [Ectopleura integra, Coryne repens, Clytia irregularis, C. seriata, Obelia alternata (resurrected here from
the synonymy of O. dichotoma), and O. microtheca] are known only from the Tropical Eastern Pacific. Three of them, E. integra,
C. irregularis, and C. seriata, are new to the Ecuadorian mainland. Species numbers were similar (range of 6 to 11 taxa) across all stations.
One-third (nine species) were found only in Galapagos samples, whereas nearly half (13 species) were found only at mainland sites. More than half (15 species)
were restricted to a single station. Previous studies, together with this work, bring the total of introduced and cryptogenic hydroid species in the Galapagos
Islands to 12 (previously eight) and nine (previously five) taxa, respectively. We recognize four introduced and eight cryptogenic hydroid species from the coast
of mainland Ecuador. |
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D. Ross Robertson, Kelly C. Kingon, Solomon Baksh, Carlos J. Estapé and Allison Morgan Estapé
The Indo-Pacific damselfish Neopomacentrus cyanomos at Trinidad, southeast Caribbean
(pp 253–268)
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The Indo-West Pacific (IWP) damselfish Neopomacentrus cyanomos was first found in the Atlantic Ocean in 2013, on reefs in Mexico in the southwest
Gulf of Mexico (GoMx). By 2018 it was known throughout most of the GoMx, but nowhere else in the Atlantic. Evidence indicates it was introduced
to the GoMx by offshore petroleum infrastructure moved in water from its native range, rather than by aquarium-release or commercial shipping.
There are three tropical Atlantic areas with offshore petroleum fields in addition to the GoMx: (i) at Trinidad (southeast Caribbean), (ii) at central
Brazil, and (iii) at west Africa. Offshore infrastructure moves between those oilfields, and between them and support facilities in the IWP.
If N. cyanomos was brought to the Atlantic by such infrastructure relocation, then it could also be at other Atlantic oilfields. To assess
that possibility, we surveyed suitable habitat at Trinidad (mid 2019), and nearby Tobago (early 2020). We found N. cyanomos at all sites
surveyed at Trinidad, but none at Tobago. At Trinidad this species was common on shallow reefs fringing an aquatic “parking lot” for mobile petroleum
infrastructure in the estuarine Gulf of Paria. These observations show that this species has well established, isolated populations at offshore
oilfields with very different environments at both ends of the Greater Caribbean and provide strong support for the petro-platform relocation hypothesis
relating to its introduction. They also show that N. cyanomos has considerable ecological plasticity, which may be important for its success.
The location of the Trinidad population at the head of the Caribbean Current should aid its spread via larval dispersal throughout the region. |
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D. Ross Robertson, Omar Dominguez-Dominguez, María Gloria Solís-Guzmán and Kelly C Kingon
Origins of isolated populations of an Indo-Pacific damselfish at opposite ends of the Greater Caribbean
(pp 269–280)
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The non-native Indo-West Pacific (IWP) damselfish Neopomacentrus cyanomos has two, recently discovered, isolated Northwest Atlantic (NWA) populations
separated by ~ 3000 km of the Caribbean Sea. One of them spans the southern and northern Gulf of Mexico (GoMx) and the other is at Trinidad, in the southeast
Caribbean. We compared DNA (CO1) sequences of 71 individuals from the southwest GoMx to those of 86 fish from Trinidad to determine similarities in their
origins. In the native range, there are four distinct, largely allopatric haplogroups, and the two NWA populations are composed of individuals
from the same two of those four haplogroups. Over 90% of individuals in each NWA population have six haplotypes shared between those populations,
and no pairwise ΦST differences in population structure (relative abundances of different haplotypes) were found between the GoMx and Trinidad populations.
Levels of haplotype diversity and nucleotide diversity are similarly high in the two NWA populations. The existence of two isolated populations in areas
with major, long-standing offshore oilfields is consistent with those fish being transported to those areas of the NWA by floating offshore infrastructure
moved from the IWP. The strong population similarities and genetic diversity of the two NWA populations indicate that both resulted from the introduction
of a substantial number of individuals from the same part of the native range. However, existing genetic and other data do not allow determination
of the sequence of events that led to the establishment of those populations, and whether one established first then effectively “seeded” the other
or both were established concurrently as a result of a single introduction. |
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Cheol Yu, Sungtae Kim, Jae-Sang Hong and Keun-Hyung Choi
The occurrence of two non-indigenous Conopeum (Bryozoa: Cheilostomata) species in the coastal waters of South Korea
(pp 281–296)
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Bryozoans are major fouling organisms and include some of the most invasive marine species globally. Hull fouling of transoceanic vessels is a major vector
of non-indigenous bryozoans. One genus known to be important in this regard is Conopeum, but its occurrence in the coastal waters of South Korea
has yet to be established. We sorted bryozoan samples from the collection of Park et al. (2017) and carried out surveys for marine organisms in 2013 and
2019–2020 in coastal waters of South Korea. We found two non-indigenous bryozoans: Conopeum reticulum (Linnaeus, 1767) and C. seurati
(Canu, 1928). These two species and a third in the genus, C. hexagonum Seo, 1996, have distinctive morphologies and distributions along environmental
gradients of the sampling sites. Gymnocyst and cryptocyst development and spine presence were used to identify each species morphologically. According
to the salinity and turbidity of the sites, the inhabiting species appeared differently. The two non-indigenous species occurred in association
with other sessile organisms such as oysters, mussels, and serpulid polychaetes. In particular, C. reticulum was associated with an invasive
species of the Mediterranean mussel (Mytilus galloprovincialis Lamarck, 1819) and C. seurati was associated with the serpulid polychaetes
Hydroides ezoensis Okuda, 1934 and Ficopomatus enigmaticus (Fauvel, 1923), as well as with the mytilid bivalve Xenostrobus securis
(Lamarck, 1819), and the Pacific oyster Crassostrea gigas (Thunberg, 1793). Conopeum seurati and H. ezoensis completely encrusted
all surfaces in artificial canal docks seemingly negatively affecting richness of native species. |
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P. Joana Dias, Sherralee S. Lukehurst, Tiffany Simpson, Rosana M. Rocha, María Ana Tovar-Hernández, Claire Wellington, Justin I. McDonald, Michael Snow and W. Jason Kennington
Multiple introductions and regional spread shape the distribution of the cryptic ascidian Didemnum perlucidum in Australia: an important baseline for management under climate change
(pp 297–313)
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Anthropogenic agents of ocean change such as biological invasions, overfishing, habitat destruction, pollution and ocean acidification and warming are known
to have a dramatic impact on marine ecosystems worldwide. They are also intrinsically connected. In Western Australia, a “hot-plate” settlement panel system aimed
at investigating the effect of ocean warming on fouling communities led to the first report of a notorious worldwide invasive ascidian species Didemnum perlucidum.
This species was subsequently recorded from numerous locations along the coast and included in the Western Australia Prevention List for Introduced Marine Pests.
In the present study we used microsatellite markers to determine whether these populations are the result of single or multiple introductions to Australia
and if anthropogenic vectors might have facilitated its spread. By including samples collected worldwide, we further aimed to evaluate broad-scale patterns of variation
and ascertain whether regional differences could be used to determine the source of introductions of D. perlucidum to Australia. Our results report an extended
geographic range for D. perlucidum in Australia and worldwide, in what is the most comprehensive genetic study of this species. Our data further supports
the introduced status of D. perlucidum in Australia, an introduction that our results suggest having occurred most likely as a result of multiple events with
subsequent admixture. The similarity between genotypes at locations in Western Australia suggests that domestic transport plays a crucial role in shaping these populations,
most likely enhanced by climatic anomalies such as heat waves. The identification of the D. perlucidum native range and sourcing of international samples from potential
sites of introduction to Australia, particularly south-east Asia, remains essential to understand the presence of this species in the country. Nevertheless, during this
study we were able to increase our understanding of D. perlucidum populations in Western Australia. This work provides an important baseline for D. perlucidum
management and protection of high value marine areas, in Australia and worldwide. |
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Sven Matern, Jens-Peter Herrmann and Axel Temming
Differences in diet compositions and feeding strategies of invasive round goby Neogobius melanostomus and native black goby Gobius niger in the Western Baltic Sea
(pp 314–328)
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The round goby Neogobius melanostomus (Pallas, 1814) is a global invader that has become established in the Baltic Sea and expands its geographic
range further west. Native in the Baltic Sea, the black goby Gobius niger Linnaeus, 1758 occupies a similar ecological niche as the round goby.
To investigate a potential dietary overlap, we sampled eleven locations between Travemünde and Flensburg by angling. We caught round goby in the coastal
areas of the Lübeck Bight, Fehmarnsund and Kiel Fjord, while black goby were caught at all sampling sites except Travemünde. Individuals of round goby
and black goby from all sites, except Kappeln, were kept for stomach content analyses. The diet analyses revealed round goby in the Western Baltic
to mainly prey on either barnacles or mollusks. Black goby had a broader prey spectrum including large amounts of crustaceans, annelids and mollusks.
Furthermore, we revealed some black goby individuals to be specialized on fish. The dietary overlap between the two goby species was low and suggests
that the absence of black goby in Travemünde cannot be referred to competition for food with round goby. |
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Liang Peng, Xianguang Xue, Jian Liao, Jian Zhao, Quehui Tang, Qiuqi Lin, Qun Zhang and Bo-Ping Han
Potential impact of population increases of non-native tilapia on fish catch and plankton structure: a case study of Tangxi Reservoir in southern China
(pp 329–348)
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Several non-native tilapia species, including Oreochromis mossambicus (Peters, 1852), O. niloticus (Linnaeus, 1757) and their hybrids
or strains, were introduced into China as major cultured species during the 1950s to 1980s. These are now among the dominant fish species in many
tropical and some subtropical reservoirs. Eutrophication is assumed to accelerate their population growth. In the present study, we reported
a sharp decline in the catch of stocked bighead carp (Hypophthalmichthys nobilis (Richardson, 1845)) with an extreme increase of tilapia catch
in a large reservoir in southern China. In 2006, the catch of tilapia was 150 tons, which exceeded the catch of stocked bighead carp, and reached
500 tons in 2015. Long-term meteorological data over the past two decades did not show any significant change, especially in minimum air and water
temperatures, which can be factors limiting tilapia growth. In contrast, water quality conditions, including total nitrogen, total phosphorus (TP),
chlorophyll a, chemical oxygen demand, and trophic status, have significantly increased in the reservoir. The phytoplankton community has been mainly
composed of small and filamentous species, while the total zooplankton biomass has decreased, with the community now mainly comprised of small rotifers
and copepod species. The high ratio of chlorophyll a:TP indicates a weakening top-down effect of zooplankton on phytoplankton.
The annual tilapia catch was significantly associated with trophic status of the reservoir, but not with meteorological and hydrological factors.
We propose an ecological mechanism for increased population densities of the non-native tilapia under eutrophication, in which an increase in tilapia
population size has been accompanied by a reduction in their body size, producing a stronger negative impact on zooplankton and water quality,
which contributes to the turnover between bighead carp and tilapia catch. The proposed mechanism provides a useful framework for understanding
the process and management of tilapia populations in tropical reservoirs. |
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Jonathan P. Fleming, Ryan M. Wersal, John D. Madsen and Eric D. Dibble
Weak non-linear influences of biotic and abiotic factors on invasive macrophyte occurrence
(pp 349–364)
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Aquatic plants (macrophytes) are important components of freshwater ecosystems and serve numerous functions, both physical and biological, that help to structure
aquatic communities. However, invasive macrophytes may negatively alter ecosystem properties. Non-native invasive species have been identified as a major cause
of biodiversity loss and the increasing prevalence of invasive species has prompted studies to help understand their impacts and to conserve biodiversity.
Studying mechanisms of invasion also gives ecological insight into how communities are structured and assembled. This study examined a set of potential factors
influencing invasion including biotic resistance, exposure, and water depth using mixed-effects models on macrophyte survey data collected from twenty-nine lakes
across the United States. The results of this study indicated that biotic resistance measured from native species richness, exposure due to fetch, and water depth
interact, often in non-linear ways to influence probability of invasive species occurrence at a given location; however, models explained a relatively low percentage
of variation in probabilities. It is likely that strong predictive principles governing macrophyte invasions do not exist, at least among comparisons across
a range of ecosystem types and environmental conditions. However, ecologists should continue to search for general patterns within definable ecosystem units
to increase understanding about factors contributing to invasibility. |
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