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LIST OF MEETING ABSTRACTS

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Oral | Posters

Oral Presentations

 

 

Day: 4, Session: 3, Talk: 1

The Effects of the Invasive Week Singapore Daisy of the Native Australian Freshwater Crayfish Tenuibranchiurus glypticus Riek

James M. Furse, Houston AJ and Wild CH

The native freshwater crayfish, Tenuibranchiurus glypticus, typically inhabits coastal Melaleuca swamps and is distributed from Maryborough (Queensland), to Wooli (New South Wales). Tenuibranchiurus glypticus is listed as “Endangered” on the IUCN Red List, primarily due to a highly fragmented distribution and habitat clearing/loss; specifically drainage of their swamps and development. It is therefore important to identify and understand any new or additional threats to allow effective management/conservation of this species in its remaining small, isolated habitat fragments. The invasive weed, Singapore daisy (Sphagneticola trilobata – Asteraceae), is successfully established in many parts of the world, including some of the seasonally inundated Melaleuca swamps which T. glypticus occupies in Southeast Queensland. The densely-matted nature of this weed is a potential problem for these small crayfish, smothering their habitat, possibly restricting access to burrows and limiting oxygen transfer at the air-water interface. The objectives of this study were to investigate if: (1) invasion of Melaleuca swamps by Singapore daisy renders them unsuitable habitat for Tenuibranchiurus, and (2) Singapore daisy infestations in Melaleuca swamps can be successfully controlled or eradicated using a primary control method of herbicide application. One hundred and fourteen paired plots of weed and no weed areas were surveyed for presence of T. glypticus across 2 sites in Southport, Queensland. We will present our findings and discuss any effects the weed is having on the presence and abundance of these crayfish. We will also discuss the effectiveness of herbicide as a control method for Singapore daisy in seasonally inundated Melaleuca swamps.

 

 

Day: 5, Session: 3, Talk: 1

KEY NOTE: Crayfish Conservation in the Alps: Strategies and Lessons Learnt

Leopold Füreder

Crayfish have played a significant role in the social and cultural activities of Europe since the Middle Ages, today however, native populations have disappeared or are highly threatened. Also in the Alpine countries, the autochthonous crayfish Astacus astacus, Austropotamobius pallipes and A. torrentium have been exposed to various threats and their populations still are strongly decreasing, mostly as a consequence of human activities. Several species protection programs have been carried out in different areas of the Alps implementing measures to enhance the situation of the indigenous species. This study aimed at documenting these activities for the support of the three autochthonous and endangered crayfish species. As these measures are being applied on three different species, in several states with different legislation, we reviewed and compared the specific management plans for crayfish conservation. Most had in common a comprehensive survey of the species’ distribution in the regions, their populations’ phenotypical and genotypical characterization, their habitat conditions and threats as well as suggestions for their protection. Based on these data, species and country specific conservation measures where summarized and now, after several years of the implementation of these programs evaluated on their success and deficits.

 

Poster Presentations

 

 

POSTER 1

Adaptive Response to Early Dominance of an Acute Invader? A Case Study of Native Crayfish

Lele S-F and Pârvulescu L

Successful invasive species compete for the same existing resources with related native species, frequently driving the latter to the cusp of extinction because of a lack of adaptive response. In this paper we analysed the behavioural relationships between two species of crayfish, the native Astacus leptodactylus and the invasive Orconectes limosus in an ongoing invasion process in the Lower Danube. We tested the species’ ability to acquire food and shelter in laboratory experiments in both intra and interspecific confrontations. Moreover, we extended the investigation in the field by collecting biometrical data from crayfish individuals in old, new and non-invaded Danube sectors in order to compare the crayfish body fitness. The innate aggressive behaviour of the invasive crayfish reveals a pattern directed even towards its congeners, while the native species displays a more tolerant conspecific behaviour. With respect to interspecific confrontation, the invasive crayfish males and females exhibited prone sex-specific dominance behaviour regarding shelters. A roughly balanced behaviour was noticed for intersexual confrontations, larger specimens being slightly more dominant. The results of this study also highlight that the occupancy of a shelter is more disputed than food resources, which appear to be opportunistically achieved. Field data revealed better body fitness indexes in non-invaded sites but also in growing populations in old invaded Danube sector. Considering those results, we hypothesise that the stress caused by dominance might lead to acute decrease of the invaded native populations biological quality and thus increasing the incidence of the crayfish plague which consequently resulted in the declines. Further investigations may reveal if there is any hope for recovery of the native species.

 

 

POSTER 7

The stone crayfish in the czech republic: lost-and-found in last seven years

Vlach P, Fischer D and Svobodová J

Within the period 2012-2015, an intensive research concerning: 1. mapping the occurrence of stone crayfish; 2. monitoring of presently known populations; 3. an evaluation of ecological demands of this species, was carried out. This contribution focuses on newly described localities, losses of some populations, and populations affected by a dramatic decrease in population densities in some localities. Moreover, the contribution introduces a hypothesis or/and particular reasons for that decrease or extinction. The extinction in Úpor brook and Hýskovský brook has already been published; recently we have recorded the following losses: Zákolanský brook, Bertínský brook, Vlcí brook, Kornatický brook, Hrádecký brook, and Medvedí brook. Whereas the combination of crayfish plague and (probably) low water quality caused the total mortality in lower part of the Zákolanský brook, crayfish plague outbreak killed crayfish in Kornatický and Hrádecký brook in 2015. Conversely, there was a lethal concentration of BOD5 in Vlcí brook. Also dramatic droughts in 2015 influenced the population densities in Chocenický and Prešínský brook. The mass mortality in Klabava was caused by a combination of stream acidification and toxic metal accumulation. The reasons for other losses are mostly speculative. On the other hand, within the mapping campaign, we found more than 10 new populations of stone crayfish. Nevertheless, the newly recorded occurrences correspond with a present range of this species in the Czech Republic.

 

 

POSTER 17

North American Branchiobdellida (Annelida: Clitellata) or Crayfish Worms in France: The Greatest Diversity of These Alien Ectosymbionts in Europe

Parpet JF and Gelder SR

Over the last five years, biomonitoring of freshwater bodies resulted in alien crayfishes being collected from the Garonne, Loire, Seine and Rhône basins in France. These crayfishes (Pacifastacus leniusculus (Dana, 1852), Procambarus clarkii (Girard, 1952), Orconectes limosus (Rafinesque, 1817)) from North America also carried ectosymbionts of the order Branchiobdellida (Annelida, Clitellata) or crayfish worms. Initially we reported (Gelder et al., 2012) the distribution in France of Xironogiton victoriensis Gelder and Hall, 1990, Cambarincola gracilis Robinson, 1954 and Cambarincola okadai Yamaguchi, 1933 on the signal crayfish, P. leniusculus, indigenous to the Pacific Northwest of North America; additional information is included here. Signal crayfish found in the Seine basin also carried Triannulata magna Goodnight, 1940, and this is the first record of this species in Europe. Louisiana red swamp crayfish, Pr. clarkii, were collected in the Adour basin along with their endemic, Cambarincola mesochoreus Hoffman, 1963. This is the first report of both host and branchiobdellidan in France. A unique host/branchiobdellidan combination was discovered when western North American X. victoriensis was observed on eastern North American spiny cheek crayfish, Orconectes limosus (Rafinesque, 1817). Although France has the most reported alien branchiobdellidan species in Europe, a number of other countries also have established North American branchiobdellidan populations. The impact of these alien species on the endemic Branchiobdella spp. is unknown, but warrants concern and further study, besides investigating their impact on other invertebrates in the freshwater ecosystem.

 

 

POSTER 19

Invader showdown: interference competition between Orconectes immunis and Pacifastacus leniusculus

Wendler F and Chucholl C

Alien crayfish are among the most damaging invaders of European inland waters and changes in the crayfish fauna should be monitored prudently. Here, we investigated for the first time direct aggressive interactions and competition for shelter between alien calico crayfish, Orconectes immunis, and signal crayfish, Pacifastacus leniusculus, which are highly invasive in Central Europe. Specifically, we monitored bouts of interspecific 1:1 combinations in laboratory experiments and offered limited shelters in a similar setting. In size- and sex-matched combinations, O. immunis won significantly more interactions than P. leniusculus; however, O. immunis females were inferior to size-matched P. leniusculus males. Similarly, P. leniusculus males were dominant over 4 mm smaller O. immunis males in chelae size-matched bouts. Both species showed a similar affinity to the provided shelter, but O. immunis was dominant in the shelter competition experiments in both sexes. The dominance of O. immunis males in size-matched combinations may be related to their greater 'resource holding potential' due to larger chelae size than P. leniusculus males. Orconectes immunis females, however, featured similar sized chelae than size-matched P. leniusculus females, and their dominance can best be explained by higher inherent aggression of O. immunis. Based on these results, O. immunis can be expected to outcompete similar sized P. leniusculus. However, since the latter invader grows considerably larger than O. immunis, and gained dominance at a size advantage of 4 mm, outcomes of interactions in the field may be much more complex, presumably also due to contrasting life-history strategies.

 

 

POSTER 23

Presence of Branchiobdellida in Five Population of Native Crayfish in Northern Italy: Preliminary Results

Fea G, Ghia D, Mazza L, and R Sacchi

Branchiobdellid annelids are commensal symbionts associated with crayfish populations, knowledge of their dispersion and distribution is generally scarce. The aim of this research was to identify the species of Branchiobdella isolated on the crayfish in different populations, and the prevalence among the species. We collected white-clawed crayfish Austropotamobius pallipes complex during the autumn 2013 from five creeks in Northern Italy. Worms were removed by inserting one-sidedly crayfish into a container with salty water (35 ppt): 1-minute each for claw, abdomen and cephalothorax; then branchiobdellids were placed into separate vials. The branchiobdellids identified, were Branchiobdella italica, Branchiobdella parasita, Branchiobdella astaci, Branchiobdella hexodonta and Branchiobdella pentodonta. We also found coexsistence of two or more species of Branchiobdella on crayfish at the same location. 46% of worms were present on abdomen and 40% cephalothorax while 14% were on claw. In all the populations studied at least two species of worms were detected and one crayfish was found to support four species of Branchiobdella.

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