Warming Threatens to Propel the Expansion of the Exotic Seagrass Halophila stipulacea

The spread of exotic species to new areas can be magnified when favored by future climatic conditions. Forecasting future ranges using species distribution models (SDMs) could be improved by considering physiological thresholds, because models solely based on occurrence data cannot account for plasticity due to acclimation of individuals to local conditions over their life-time or to adaptation due to selection within local populations. This is particularly relevant for the exotic seagrass Halophila stipulacea, which colonized the Mediterranean Sea a century ago and shifted its thermal niche, coping with a colder regime. Here, we used two hybrid models combining correlative SDMs with the thermal limits for growth of native and exotic H. stipulacea populations to predict the distribution of the species in its native (Indian Ocean and Red Sea) and exotic ranges (Mediterranean Sea and Caribbean Sea) under two scenarios forecasting limited (RCP 2.6) and severe (RCP 8.5) future climate changes by 2050 and 2100. Then, we assessed the differences between hybrid models based on native Red Sea thermal limits (niche conservatism: 17–36°C) and on exotic Mediterranean thermal limits (local adaptation: 14–36°C). At the Mediterranean exotic range, the local adaptation hybrid model accurately agreed with the present distribution of the species while the niche conservatism-based hybrid model failed to predict 87% of the current occurrences of the species. By contrast, both hybrid models predicted similar species distributions for the native range and exotic Caribbean range at present and projected that H. stipulacea will maintain its current worldwide under all future greenhouse gas emission scenarios. The hybrid model based on Mediterranean thermal limits projected the expansion of H. stipulacea through the western Mediterranean basin (except the gulf of Leon) under the most severe scenario (RCP 8.5) by 2100, increasing its distribution by 50% in the Mediterranean. The future expansion of H. stipulacea is related to its capacity to cope with warm waters and it may become a relevant species in the future, particularly under the projected decline of native Mediterranean seagrasses, resulting in important shifts in seagrass communities and overall ecosystem functions.

Download Full-text

Tropical seagrass Halophila stipulacea shifts thermal tolerance during Mediterranean invasion

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.3001 ◽

2020 ◽

Vol 287 (1922) ◽

pp. 20193001 ◽

Cited By ~ 4

Author(s):

Marlene Wesselmann ◽

Andrea Anton ◽

Carlos M. Duarte ◽

Iris E. Hendriks ◽

Susana Agustí ◽

...

Keyword(s):

Mediterranean Sea ◽

Red Sea ◽

Thermal Tolerance ◽

Seawater Temperature ◽

Mediterranean Populations ◽

Thermal Thresholds ◽

Thermal Niche ◽

Thermal Limits ◽

Halophila Stipulacea ◽

The Mediterranean

Exotic species often face new environmental conditions that are different from those that they are adapted to. The tropical seagrass Halophila stipulacea is a Lessepsian migrant that colonized the Mediterranean Sea around 100 years ago, where at present the minimum seawater temperature is cooler than in its native range in the Red Sea. Here, we tested if the temperature range in which H. stipulacea can exist is conserved within the species or if the exotic populations have shifted their thermal breadth and optimum due to the cooler conditions in the Mediterranean. We did so by comparing the thermal niche (e.g. optimal temperatures, and upper and lower thermal limits) of native (Saudi Arabia in the Red Sea) and exotic (Greece and Cyprus in the Mediterranean Sea) populations of H. stipulacea . We exposed plants to 12 temperature treatments ranging from 8 to 40°C for 7 days. At the end of the incubation period, we measured survival, rhizome elongation, shoot recruitment, net population growth and metabolic rates. Upper and lower lethal thermal thresholds (indicated by 50% plant mortality) were conserved across populations, but minimum and optimal temperatures for growth and oxygen production were lower for Mediterranean populations than for the Red Sea one. The displacement of the thermal niche of exotic populations towards the colder Mediterranean Sea regime could have occurred within 175 clonal generations.

Download Full-text

Differences in flowering sex ratios between native and invasive populations of the seagrass Halophila stipulacea

Botanica Marina ◽

10.1515/bot-2018-0015 ◽

2018 ◽

Vol 61 (4) ◽

pp. 337-342 ◽

Cited By ~ 8

Author(s):

Hung Manh Nguyen ◽

Periklis Kleitou ◽

Demetris Kletou ◽

Yuval Sapir ◽

Gidon Winters

Keyword(s):

Sex Ratio ◽

Mediterranean Sea ◽

Red Sea ◽

Sex Ratios ◽

Dioecious Plants ◽

Halophila Stipulacea ◽

The Mediterranean ◽

Northern Red Sea ◽

Rare Group

Abstract Deviations from the 1:1 sex ratio are common in dioecious plants. The tropical seagrass Halophila stipulacea is among an extremely rare group of dioecious plants that are widely recognized as female-biased. Here we report on differences in sex ratios between native (Eilat, northern Red Sea) and invasive (Cyprus, Mediterranean Sea) populations. While H. stipulacea populations were female-biased in their native region, invasive populations were either male- or female-biased. The existence of both sexes simultaneously in the Mediterranean invasive populations might help its ongoing expansion in the Mediterranean, thereby threatening local seagrasses species.

Download Full-text

Radiocarbon dating of individual foram tests show that alleged Lessepsian species are of Holocene age

10.5194/egusphere-egu21-6206 ◽

2021 ◽

Author(s):

Paolo G. Albano ◽

Anna Sabbatini ◽

Jonathan Lattanzio ◽

Jan Steger ◽

Sönke Szidat ◽

...

Keyword(s):

Mediterranean Sea ◽

Red Sea ◽

Native Species ◽

Radiocarbon Dating ◽

Suez Canal ◽

Tropical Species ◽

Indigenous Species ◽

Last Interglacial ◽

Sediment Depth ◽

The Mediterranean

The Lessepsian invasion &#8211; the largest marine biological invasion &#8211; followed the opening of the Suez Canal in 1869 (81 years BP). Shortly afterwards, tropical species also distributed in the Red Sea appeared on Mediterranean shores: it was the dawn of what would become the invasion of several hundred tropical species. The time of the Suez Canal opening coincided with an acceleration in natural history exploration and description, but the eastern sectors of the Mediterranean Sea lagged behind and were thoroughly explored only in the second half of the 20th century. Many parts are still insufficiently studied today. Baseline information on pre-Lessepsian ecosystem states is thus scarce. This knowledge gap has rarely been considered by invasion scientists: every new finding of species belonging to tropical clades has been assumed to be a Lessepsian invader.We here question this assumption by radiocarbon dating seven individual tests of miliolids &#8211; imperforated calcareous foraminifera &#8211; belonging to five alleged non-indigenous species. Tests were found in two sediment cores collected at 30 and 40 m depth off Ashqelon, on the Mediterranean Israeli shelf. We dated one Cribromiliolinella milletti (core at 40 m, 20 cm sediment depth), three Nodophthalmidium antillarum (core at 40 m, 35 cm sediment depth), one Miliolinella cf. fichteliana (core at 30 m, 110 cm sediment depth), one Articulina alticostata (core at 40 m, 35 cm sediment depth) and one Spiroloculina antillarum (core at 30 m, 110 cm sediment depth). All foraminiferal tests proved to be of Holocene age, with a median calibrated age spanning between 749 and 8285 years BP. Only one test of N. antillarum showed a 2-sigma error overlapping the time of the opening of the Suez Canal, but with a median age of 1123 years BP. Additionally, a thorough literature search resulted in a further record of S. antillarum in a core interval dated 1820&#8211;2064 years BP in Turkey.Therefore, these foraminiferal species are not introduced, but native species. They are all circumtropical or Indo-Pacific and in the Mediterranean distributed mostly in the eastern sectors (only S. antillarum occurs also in the Adriatic Sea). Two hypotheses can explain our results: these species are Tethyan relicts that survived the Messinian salinity crisis (5.97&#8211;5.33 Ma) and the glacial periods of the Pleistocene in the Eastern Mediterranean, which may have never desiccated completely during the Messinian crisis and which may have worked as a warm-water refugium in the Pleistocene; or they entered the Mediterranean Sea from the Red Sea more recently but before the opening of the Suez Canal, for example during the Last Interglacial (MIS5e) high-stand (125,000 years BP) when the flooded Isthmus of Suez enabled exchanges between the Mediterranean and the Indo-Pacific fauna. The recognition that some alleged Lessepsian invaders are in fact native species influences our understanding of the invasion process, its rates and environmental correlates.

Download Full-text

Tintinnids (Ciliophora: Choreotrichia) of the Suez Canal and their transmigration process between the Red Sea and the Mediterranean Sea

Aquatic Ecosystem Health & Management ◽

10.1080/14634988.2014.979601 ◽

2014 ◽

Vol 17 (4) ◽

pp. 454-462

Author(s):

Hamed A. El-Serehy ◽

Fahad A. Al-Misned ◽

Nasser S. Abdel-Rahman ◽

Khaled A. Al-Rasheid

Keyword(s):

Mediterranean Sea ◽

Red Sea ◽

Suez Canal ◽

The Mediterranean

Download Full-text

Local adaptation of a Lessepsian invader species to winter conditions in the Mediterranean Sea

10.5194/egusphere-egu21-14762 ◽

2021 ◽

Author(s):

Débora Silva Raposo ◽

Raphaël Morard ◽

Christiane Schmidt ◽

Michal Kucera

Keyword(s):

Quantum Yield ◽

Mediterranean Sea ◽

Red Sea ◽

Photosynthetic Activity ◽

Eastern Mediterranean ◽

Effective Quantum Yield ◽

Mediterranean Populations ◽

Cold Temperatures ◽

Invasion Front ◽

The Mediterranean

In recent decades the &#8220;Lessepsian&#8221; migration caused a rapid change in the marine community composition due to the invasion of alien species from the Red Sea into the Mediterranean Sea. Among these invaders is the large benthic foraminifera Amphistegina lobifera, a diatom-bearing species that recently reached the invasion front in Sicily. There it copes with colder winters and broader temperature than in its original source, the Red Sea. It is not yet known how (or if) the population from the invasion front has developed adaptation to this new thermal regime. Understanding the modern marine invasive patterns is a crucial tool to predict future invasive successes in marine environments. Therefore, in this study we aim to evaluate the physiological responses to cold temperatures of A. lobifera populations at three different invasive stages: source (Red Sea), early invader (Eastern Mediterranean) and invasion front (Sicily). For this, we conducted a culturing experiment in which we monitored the responses of the foraminifera (growth, motility) to temperatures of 10, 13, 16, 19&#176;C + control (25&#176;C) over four weeks. To address what is the role of their endosymbionts in the adaptation process, we also monitored their photosynthetic activity (Pulse Amplitude Modulation - PAM fluorometer) during the experiment. The growth rate of the foraminifera was reduced for all populations below 19&#176;C as well as the motility, reduced until 16&#176;C and dropping to zero below 13&#176;C. The response of the endosymbionts was however different. There was a reduced photosynthetic activity of the Red Sea and Eastern Mediterranean populations at colder temperatures observed by the lower maximum quantum yield (Fv:Fm) and effective quantum yield (Y(II)), when compared to their initial levels and to the other treatments. In the meantime, the endosymbionts of the Sicily population stood out with the highest photosynthetic activity (Fv:Fm and Y(II)) in the treatments bellow 13 &#176;C (P < 0.05). In conclusion, we observed that while the host responses were similar between the three populations, the endosymbionts from the invasion front population shows the best performance at colder temperatures. This suggests that the photo-symbiosis has an important role in adaptation, most likely being a key factor to the success of past and future migrations.

Download Full-text

Bacterial Taxa Migrating from the Mediterranean Sea into the Red Sea Revealed a Higher Prevalence of Anti-Lessepsian Migrations

OMICS A Journal of Integrative Biology ◽

10.1089/omi.2020.0140 ◽

2021 ◽

Vol 25 (1) ◽

pp. 60-71

Author(s):

Esraa Elsaeed ◽

Nora Fahmy ◽

Amro Hanora ◽

Shymaa Enany

Keyword(s):

Mediterranean Sea ◽

Red Sea ◽

The Mediterranean

Download Full-text

Present Development Phases of the Suez Canal Project

Journal of Navigation ◽

10.1017/s0373463300021834 ◽

1982 ◽

Vol 35 (3) ◽

pp. 460-465

Author(s):

Nabil Hilaly

Keyword(s):

Mediterranean Sea ◽

Red Sea ◽

World Trade ◽

Nile Delta ◽

Suez Canal ◽

Development Phases ◽

The Mediterranean

It is recorded that Egypt was the first country to dig a canal to promote world trade; the first canal was dug in the reign of Pharaoh Senusret III (1887–1849 B.C.), to link the Mediterranean Sea with the Red Sea through the Nile delta. This canal, often abandoned due to silting, was reopened for navigation by later Pharaohs and finally by Amro Ibn El Ass in A.D. 640 after which it remained open for 150 years.

Download Full-text