Historical introduction, overview, and reproductive biology of the protochordates

Lambert, Charles C.

doi:10.1139/z04-160

Cited by 68 publications

(29 citation statements)

References 88 publications

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“…Invasive ascidians, among many other features, characterized by rapid growth rates, early sexual maturation, and a high reproductive effort manifested in prolonged reproduction seasons (Lambert, 2001(Lambert, , 2002. All of this, combined with their broad environmental tolerance (Naranjo et al, 1997;Lowe, 2002;Lambert, 2005a;Pineda et al, 2012), has enabled invasive ascidians to establish thriving populations worldwide. Out of 33 ascidian species with introduction records in the Mediterranean (Coll et al, 2010), 7 alien ascidians have been reported from the coast of Israel (Shenkar and Loya, 2009), and only few studies have focused on their reproductive biology (Shenkar and Loya, 2008).…”

Section: Introductionmentioning

confidence: 99%

From Tropical to Sub-Tropical: Prolonged Reproductive Activity of the Invasive Ascidian Microcosmus exasperatus in the Eastern Mediterranean

Nagar

Shenkar

2016

Front. Ecol. Evol.

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The solitary ascidian Microcosmus exasperatus is globally distributed in tropical and sub-tropical waters. In the Mediterranean it is considered an invasive species introduced through the Suez Canal, with a restricted distribution in the eastern basin. In order to understand the potential of this species to establish sustainable communities at additional sites in the Mediterranean, we studied its reproduction cycle over a 2-year period in relation to seawater temperature and chlorophyll-a data. Although M. exasperatus reproduces seasonally, with significantly greater activity in summer and early fall, mature oocytes occur throughout the year, suggesting multiple spawning periods. We found that reproductive effort significantly correlated with seawater temperature, while chlorophyll-a showed a low and insignificant explanatory power. A combined regression model of both parameters yielded the highest explained variance, suggesting a synergic effect of these two factors. Such a prolonged reproductive activity period enables repeated recruitment events. In view of the anticipated rise in seawater temperature, we predict that this species will gradually expand its distribution further across the Mediterranean.

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Section: Introductionmentioning

confidence: 99%

From Tropical to Sub-Tropical: Prolonged Reproductive Activity of the Invasive Ascidian Microcosmus exasperatus in the Eastern Mediterranean

Nagar

Shenkar

2016

Front. Ecol. Evol.

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“…Ascidians or sea squirts (Chordata: Tunicata) are sessile, filter‐feeding organisms that occur in benthic ecosystems across a broad range of depths and latitudes (Lambert ). These animals are notorious for their detrimental effects on aquaculture facilities, as fouling organisms attached to ship hulls (Turner et al.…”

mentioning

confidence: 99%

Growing or reproducing in a temperate sea: optimization of resource allocation in a colonial ascidian

López‐Legentil

Erwin

Velasco

et al. 2013

Invertebrate Biology

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Relatively little is known about the life cycles of ascidians in temperate seas. Here, we investigated the biological cycle of the colonial ascidian Didemnum fulgens, a dominant species in some shallow localities of the NW Mediterranean Sea. Growth rates and frequencies of fission/fusion events were calculated over a period of 13 months, and the reproductive cycle determined after 32 months of observation. For analyses of reproduction, zooids were dissected in the laboratory and classified into five reproductive categories; these data were used to calculate a maturity index. For growth analyses, underwater photographs of marked colonies were used to estimate the surface area of D. fulgens colonies, calculate monthly growth rates, and document fusion and fission events. Clear seasonal patterns in reproduction and growth were observed, with distinct periods of investment into each function. Gonad maturation started in winter and larval release occurred in early summer, just before maximal sea temperatures were reached. After reproducing, colonies shrank and aestivated during the warmer summer months. Growth occurred during the cooler months, with maximal and minimal growth rates observed in winter and summer, respectively. Fusions and fissions occurred year‐round, although fissions were more frequent in fall (coincident with high growth rates) and fusions in spring (coincident with reproduction). These results add to the mounting evidence that ascidian life cycles in temperate seas are characterized by a trade‐off between investment in reproduction and growth, triggered by seasonal temperature shifts and constrained by resource availability during summer.

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“…Such conditions may also lead to an earlier fusion of colonies in degraded waters Shenkar et al 2008). Despite constant recruitment in non-degraded waters, colonies may be restrained from fusion by environmental factors such as resource availability or competing invertebrate species (Lambert 2005;Dias et al 2008;López-Legentil et al 2013). …”

Section: Abundancementioning

confidence: 99%

The highly competitive ascidian Didemnum sp. threatens coral reef communities in the Wakatobi Marine National Park, Southeast Sulawesi, Indonesia

Roth

Powell

Smith

et al. 2018

Regional Studies in Marine Science

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Coral reefs in the Wakatobi Marine National Park (WMNP), Indonesia, are protected but have been degrading in several areas due to local anthropogenic stressors. In affected areas, benthic surveys revealed the occurrence of a dominant ascidian species of the genus Didemnum, which may negatively impact the benthic community composition and structure. We quantified the abundance, substrate preference, and growth rate of Didemnum sp. in non-degraded and degraded reefs to assess its impact on the benthic community. While Didemnum sp. occurred in similar high abundances in both, non-degraded (0.66%) and degraded (0.75 %) reef sites, this species showed a substantially (> 10-fold) increased growth rate in degrading reefs (2.7 ± 0.98% day⁻¹ increase in colony size, compared to 0.17 ± 0.39 % day⁻¹ in non-degraded reefs). Furthermore, Didemnum sp. colonized many different substrates and showed the ability to overgrow live corals quickly. These observations indicate that Didemnum sp. can be a severe threat to a reef community by outcompeting live corals and call for further studies on the interaction between environmental pollution and Didemnum growth patterns in coral reefs.

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Historical introduction, overview, and reproductive biology of the protochordates

Cited by 68 publications

References 88 publications

From Tropical to Sub-Tropical: Prolonged Reproductive Activity of the Invasive Ascidian Microcosmus exasperatus in the Eastern Mediterranean

From Tropical to Sub-Tropical: Prolonged Reproductive Activity of the Invasive Ascidian Microcosmus exasperatus in the Eastern Mediterranean

Growing or reproducing in a temperate sea: optimization of resource allocation in a colonial ascidian

The highly competitive ascidian Didemnum sp. threatens coral reef communities in the Wakatobi Marine National Park, Southeast Sulawesi, Indonesia

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