I would like to acknowledge the many researchers, students, teachers, and citizen scientists who have tested and helped me improve this protocol over the past several years: Dr. Gabriela Bradt, Dr. Robert Steneck, Erica Ferrelli, Ethel Wilkerson, Susan Ayers and the Georgetown Central School 3rd and 4th grade students, Julie Upham and the West Bath Elementary 4th grade students, the GMRI Vital Signs team, and the Idexx Laboratories Community Service Volunteers. I thank Anne Hayden, Caitlin Cleaver, and Hannah Webber for providing comments and suggestions on this manuscript. I thank the following funding sources for supporting the development and execution of this protocol: NOAA Saltonstall-Kennedy Grant Program (Grant #NA18NMF4270194), Maine Sea Grant, Robert and Patricia Switzer Foundation, and the Georgetown Island Education Fund. Finally, this manuscript was greatly improved thanks to comments and edits provided by three anonymous reviewers.

1. Timing of survey work
<ol>
	<li>Conduct surveys between May-November, during the height of productivity in the intertidal zone.</li>
	<li>Schedule surveys around negative or zero tides (generally new and full moon cycles) to allow for adequate time in the low intertidal zone (i.e., at least 2 hours).</li>
</ol>
2. Pre-survey preparation
<ol>
	<li>Locate and print all field guides and data collection sheets (see Appendices) prior to conducting the survey if that is the preferred method. If using the Anecdata app for field guides and data collection, visit the Anecdata website and join the Intertidal Green Crab Project19. The data collection sheet and Anecdata collection categories are identical.</li>
</ol>
3. Site selection and description
<ol>
	<li>Locate a wave-sheltered rocky intertidal site with cobble (i.e., not stable, rolled by wave action) and algal canopy habitat. Ensure that there is at least 100 m of shoreline to accommodate the planned sampling.</li>
	<li>Record the location of the study site using a global positioning system (GPS) unit, or a device such as a smart phone that has GPS capability (e.g., many compass apps are free to download or are already pre-programmed on smart phones). Record site coordinates on the Intertidal Survey Data Sheet (Appendix 3) or directly into the Intertidal Green Crab Project on Anecdata.</li>
	<li>At the predicted low tide time (determined from the NOAA Tide Predications website or an app such as Tides) run a 50 m transect tape vertically from the low intertidal zone (i.e., the splash zone) to the high intertidal zone (i.e., the black microalgal zone that is typically dry at high tide). Divide the resulting distance into three equal sections: high, middle, and low (Figure 1). The low intertidal section, parallel to the shoreline, is the target sampling area.</li>
	<li>Within the low intertidal zone, measure a distance of 100 m parallel to the shoreline (Figure 2) and establish permanent markers delineating this zone using rebar or natural permanent landmarks such as immovable boulders, ledge, dock pilings, etc.</li>
</ol>
4. Conducting survey
<ol>
	<li>Prior to arriving at the survey site, record the following information on the Intertidal Survey Data Sheet (Appendix 3) or directly into the Intertidal Green Crab Project on Anecdata: site name, sampling date, participants, time and height of low tide at the location/date to be sampled (determined using the NOAA Tide Predications website, or an app such as Tides), and lunar phase (determined using a lunar calendar such as www.moongiant.com).</li>
	<li>Upon arriving at the survey site, locate the 100 m section of low intertidal shoreline where the survey will be conducted, unpack gear, and organize data sheets and field guides.</li>
	<li>Optionally, measure water temperature using a waterproof digital thermometer in the shallow water adjacent to the sampling area.
	<ol>
		<li>Measure salinity by placing several drops of water collected adjacent to the sampling area onto the refraction prism of a salinity refractometer.</li>
		<li>Record water temperature in &#176;C and salinity in parts per thousand (ppt) on the Intertidal Survey Data Sheet or directly into the Intertidal Green Crab Project on the Anecdata app.</li>
	</ol>
	</li>
	<li>Begin the survey by haphazardly tossing the 1 m2 quadrat within the predefined low intertidal zone area that runs parallel to the shoreline (a transect tape is not needed to conduct the survey because the sample area has already been defined). Record a visual estimate of the percent of both moveable rock (i.e., cobble/gravel that you can look underneath) and algae canopy cover (e.g. Ascophyllum or Fucus spp.) within the quadrat to the nearest quarter percent (i.e., 0, 25, 50, 75, or 100%). A rocky intertidal habitat is often patchy and can contain areas of sand, mud, ledge, or other habitats where green crabs are not found.
	<ol>
		<li>To avoid skewing density estimates by sampling unsuitable habitat, only sample quadrats with greater than 50% movable rock, or greater than 50% algal canopy. Also avoid sampling areas where boulders or ledges are noticeably elevated above the profile of the shoreline within the low intertidal zone, as this habitat may be more representative of the mid intertidal zone.</li>
	</ol>
	</li>
	<li>Within each quadrat, lift moveable rocks or cobble and carefully move aside algae to look for crabs. Be sure to replace all rocks and algae as they are found. Collect all of the crabs found and store them in a bucket until the entire quadrat has been searched.</li>
	<li>Identify the species of each crab using the Intertidal Crab Field Guide (Appendix 1, or source on Anecdata project platform) and record using the species codes listed on the Intertidal Survey Data Sheet (Appendix 3) or on the Intertidal Green Crab Project on the Anecdata app.</li>
	<li>Measure the carapace width (CW) of each crab across the widest part of the carapace, spanning from tip to tip of the terminal spines, to the nearest 1 mm using Vernier calipers.</li>
	<li>Use the abdomen (or &#8216;apron&#8217;) on the ventral side of the crab to determine sex. Male crabs tend to have a narrow, pointed abdomen and female crabs tend to have a wider, beehive shaped abdomen (Appendix 1). Only record sex for crabs &#8805; 10 mm CW.</li>
	<li>For all crabs, record number of claws, number of legs, shell condition (i.e., hard- or soft-shell as determined by whether the carapace resists (hard) or gives (soft) when finger pressure is applied), and the presence (i.e., ovigerous) or absence of extruded eggs for females.</li>
	<li>Optionally, record the color for green crabs, but not other crab species, using the color protocol developed by Young and Elliot20 (Appendix 2). This protocol should only be used if the actual paint chips can be sourced and brought into the field, as printed versions can vary substantially. Identify pre-molt shell condition for green crabs using external pre-molt indicators (Appendix 4, or source on Anecdata project platform). Pre-molt green crabs are within 3 weeks of molting and are of particular interest to the emerging soft-shell green crab fishery21,22.</li>
	<li>Return all crabs to the habitat within the quadrat once all measurements and characteristics have been recorded.</li>
	<li>Continue haphazardly tossing the quadrat within the predefined low intertidal area until a total of 10 m2 is sampled. Continually move forward along the low intertidal area of shoreline and ensure that quadrats are separated by a minimum of 1 m so that resampling does not occur and a maximum of 10 m so that the survey area does not exceed 100 m.</li>
</ol>
5. Data management and analysis
<ol>
	<li>If using data sheets, check all raw data sheets for errors and legibility post-survey, photocopy, scan, and archive. Use the photocopy for data entry into an excel spreadsheet (see Appendix 5 for example) or into the Intertidal Green Crab Project on Anecdata19. Store scanned data sheets electronically.</li>
	<li>Conduct data analyses appropriate to the design of the study. Useful population metrics include crab density (total number of crabs divided by total number of quadrats sampled), sex ratio, cumulative size frequency, injury rate, shell condition ratio, and overall species encounter rates (e.g., % of native vs. invasive crabs).</li>
</ol>

<ol>
	<li>Barnosky, A. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Approaching+a+state+shift+in+Earth's+biosphere.">Approaching a state shift in Earth's biosphere.</a> Nature. 486, 52-58 (2012).</li><li>Butchart, S. H. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+biodiversity:+indicators+of+recent+declines.">Global biodiversity: indicators of recent declines.</a> Science. 328, 1164-1168 (2010).</li><li>Grosholz, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ecological+and+evolutionary+consequences+of+coastal+invasions.">Ecological and evolutionary consequences of coastal invasions.</a> Trends in Ecology and Evolution. 17, 22-27 (2002).</li><li>Marbuah, G., Gren, I. M., McKie, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Economics+of+harmful+invasive+species:+A+review.">Economics of harmful invasive species: A review.</a> Diversity. 6, 500-523 (2014).</li><li>Kamenova, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Invasions+toolkit:+current+methods+for+tracking+the+spread+and+impact+of+invasive+species.">Invasions toolkit: current methods for tracking the spread and impact of invasive species.</a> Advances in Ecological Research 2017. 56, 85-182 (2017).</li><li>Carlton, J. T., Cohen, A. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Episodic+global+dispersal+in+shallow+water+marine+organisms:+The+case+history+of+the+European+shore+crabs+Carcinus+maenas+and+C.+aestuarii.">Episodic global dispersal in shallow water marine organisms: The case history of the European shore crabs Carcinus maenas and C. aestuarii.</a> Journal of Biogeography. 30, 1809-1820 (2003).</li><li>Klassen, G. J., Locke, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+biological+synopsis+of+the+European+green+crab,+Carcinus+maenas.+Fisheries+and+Oceans+Canada.">A biological synopsis of the European green crab, Carcinus maenas. Fisheries and Oceans Canada.</a> Canadian Manuscript Report of Fisheries and Aquatic Sciences. 2818, (2007).</li><li>Baeta, A., Cabral, H. N., Marques, J. C., Pardal, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feeding+ecology+of+the+green+crab,+Carcinus+maenas+(L.+1758)+in+a+temperate+estuary,+Portugal.">Feeding ecology of the green crab, Carcinus maenas (L. 1758) in a temperate estuary, Portugal.</a> Crustaceana. 79, 1181-1193 (2006).</li><li>Pickering, T., Quij&#243;n, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potential+effects+of+a+non-indigenous+predator+in+its+expanded+range:+assessing+green+crab,+Carcinus+maenas,+prey+preference+in+a+productive+coastal+area+of+Canada.">Potential effects of a non-indigenous predator in its expanded range: assessing green crab, Carcinus maenas, prey preference in a productive coastal area of Canada.</a> Marine Biology. 158, 2065-2078 (2011).</li><li>Rossong, M. A., Williams, P. J., Comeau, M., Mitchell, S. C., Apaloo, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Agonistic+interactions+between+the+invasive+green+crab,+Carcinus+maenas+(Linnaeus)+and+juvenile+American+lobster,+Homarus+americanus+(Milne+Edwards).">Agonistic interactions between the invasive green crab, Carcinus maenas (Linnaeus) and juvenile American lobster, Homarus americanus (Milne Edwards).</a> Journal of Experimental Marine Biology and Ecology. 329, 281-288 (2006).</li><li>Rossong, M. A., Quijon, P. A., Williams, P. J., Snelgrove, P. V. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Foraging+and+shelter+behavior+of+juvenile+American+lobster+(Homarus+americanus):+the+influence+of+a+non-indigenous+crab.">Foraging and shelter behavior of juvenile American lobster (Homarus americanus): the influence of a non-indigenous crab.</a> Journal of Experimental Marine Biology and Ecology. 403, 75-80 (2011).</li><li>Matheson, K., Gagnon, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+temperature,+body+size,+and+chela+loss+on+competition+for+a+limited+food+resource+between+indigenous+rock+crab+(Cancer+irroratus+Say)+and+recently+introduced+green+crab+(Carcinus+maenas+L).">Effects of temperature, body size, and chela loss on competition for a limited food resource between indigenous rock crab (Cancer irroratus Say) and recently introduced green crab (Carcinus maenas L).</a> Journal of Experimental Marine Biology and Ecology. 428, 49-56 (2012).</li><li>Davis, R. C., Short, F. T., Burdick, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+the+effects+of+green+crab+damage+to+eelgrass+transplants.">Quantifying the effects of green crab damage to eelgrass transplants.</a> Restoration Ecology. 6, 297-302 (1998).</li><li>Garbary, D. J., Miller, A. G., Williams, J., Seymour, N. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drastic+decline+of+an+extensive+eelgrass+bed+in+Nova+Scotia+due+to+the+activity+of+the+invasive+green+crab+(Carcinus+maenas).">Drastic decline of an extensive eelgrass bed in Nova Scotia due to the activity of the invasive green crab (Carcinus maenas).</a> Marine Biology. 161, 3-15 (2014).</li><li>Congleton, W. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trends+in+Maine+softshell+clam+landings.">Trends in Maine softshell clam landings.</a> Journal of Shellfish Research. 25, 475-480 (2006).</li><li>Pershing, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Slow+adaptation+in+the+face+of+rapid+warming+leads+to+collapse+of+the+Gulf+of+Maine+cod+fishery.">Slow adaptation in the face of rapid warming leads to collapse of the Gulf of Maine cod fishery.</a> Science. 350, 809-812 (2015).</li><li>Young, A. M., Elliott, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Life+history+and+population+dynamics+of+green+crabs+(Carcinus+maenas).">Life history and population dynamics of green crabs (Carcinus maenas).</a> Fishes. 5, (2019).</li><li>Young, A. M., Elliott, J. A., Incatasciato, J. M., Taylor, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Seasonal+catch,+size,+color,+and+assessment+of+trapping+variables+for+the+European+green+crab+Carcinus+maenas+(Brachyura:+Portunoidea:+Carcinidae),+a+nonindigenous+species+in+Massachusetts,+USA.">Seasonal catch, size, color, and assessment of trapping variables for the European green crab Carcinus maenas (Brachyura: Portunoidea: Carcinidae), a nonindigenous species in Massachusetts, USA.</a> Journal of Crustacean Biology. 37, 556-570 (2017).</li><li>St-Hilaire, S., Krause, J., Wright, K., Poirier, L., Singh, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Break-even+analysis+for+a+green+crab+fishery+in+PEI,+Canada.">Break-even analysis for a green crab fishery in PEI, Canada.</a> Management of Biological Invasions. 7, 297-303 (2016).</li><li>Poirier, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Moulting+synchrony+in+green+crabs+(Carcinus+maenas)+from+Prince+Edward+Island,+Canada.">Moulting synchrony in green crabs (Carcinus maenas) from Prince Edward Island, Canada.</a> Marine Biology Research. 12, 969-977 (2016).</li><li>Peters, G. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+challenge+to+keep+global+warming+below+2+C.">The challenge to keep global warming below 2 C.</a> Nature Climate Change. 3, 4-6 (2013).</li><li>Masson-Delmotte, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IPCC.+Summary+for+Policymakers.">IPCC. Summary for Policymakers.</a> Global Warming of 1.5 &#176;C. 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The author has nothing to disclose.

This protocol describes a survey method for assessing spatial and temporal trends of crab populations in the rocky intertidal zone that is accessible to multiple users including researchers, educators, students, and citizen scientists. The benefits of this protocol include the following: it does not require specialized or expensive equipment, the methodology is approachable for a wide range of skill levels (e.g., 3rd and 4th grade students have successfully used it), and it can easily be adapted to ...

Biological invasions can potentially disrupt species interactions and ecological processes, and may have far reaching ecological1,2,3 and economic consequences4. The ability to successfully predict, mitigate, and adapt to invasions strongly depends on characterizing spatiotemporal population dynamics5. While a range of tools exist (e.g., population genetics, stable isotopes) and are emerging (e.g., eDNA) for tracking invasive species, traditional in situ monitoring techniques continue to be widely utilized for assessing invasive species distribution and abundance.
The European green crab (Carcinus maenas) is an invasive species that was first detected in North America in 1817 and has successfully invaded ecosystems worldwide6,7. Green crabs have a multitude of negative impacts on local ecosystems, including reducing native bivalve populations through predation8,9, competing with native crustaceans for food and shelter10,11,12 and destruction of eel grass habitat and subsequent changes to fish community structure12,13,14. Compounding these issues is the link between increasing temperature and increasing green crab abundance and/or range expansion15,16, which has had severe ecological and socio-economic consequences in areas such as the Gulf of Maine, where warming is occurring faster than 99% of the world&#8217;s other oceans17.
On the eastern seaboard of North America, green crabs range from Virginia to Newfoundland. They are most commonly found on wave-protected shorelines, estuaries, and embayments in depths ranging from the high tide level to 5-6 m18. Their presence in the intertidal zone makes them an ideal marine species for shoreline surveys. The most distinguishing characteristic used to identify green crabs is the pattern of five spines or &#8216;teeth&#8217; on each side of the eyes and three spines between the eyes (see Appendix 1). Their carapace (dorsal side) is typically a mottled dark green and brown, but ventral color patterns can vary greatly (see Appendix 2).
There are many organizations, researchers, citizen scientist groups, and educators currently conducting green crab population monitoring. However, the lack of a standardized protocol makes it difficult to compare datasets and to ultimately understand green crab populations on both a local and regional scale. This protocol is designed to quantify spatiotemporal population dynamics of green crabs in the rocky intertidal zone in New England and Atlantic Canada. Ideally, the development of a standardized, inexpensive, and easily adaptable survey will promote long-term monitoring efforts by a wide range of users, including researchers, citizen scientists, educators, and students.
Although green crabs are the target species of interest in this protocol, data is also collected for native Jonah and rock crabs (Cancer borealis and Cancer irroratus), as well as the invasive Asian shore crab (Hemigrapsus sanguineus). These are crab species commonly found in the rocky intertidal zone in northern New England, and trends in their population distribution and abundance have ecological and economic significance. An Intertidal Crab Field Guide was developed alongside this protocol to aid in crab identification (Appendix 1) specific to northern New England. A data entry and storage platform called &#8220;Intertidal Green Crab Project&#8221; was also developed for this protocol using Anecdata19. Anecdata is a free online citizen science platform that provides web-based and mobile solutions for gathering and accessing observations, and provides a user-friendly platform to easily collect, manage, and share data.

<table><tbody><tr><td>1 m&lt;sup&gt;2&lt;/sup&gt; PVC quadrat (1/2&quot; PVC)</td><td>Any hardware/home improvement store</td><td></td><td>PVC can be sourced at any hardware/home improvement store and cut into 1m lengths to form quadrat (4 1/2&quot; PVC elbows will also be needed to connect 1 m lengths into square)</td></tr><tr><td>1/2&quot; rebar</td><td>Home depot</td><td>5152</td><td>*optional (for marking low intertidal area)</td></tr><tr><td>40 m Fiberglass Transect Tape</td><td>Grainger</td><td>3LJX1</td><td></td></tr><tr><td>5 gal bucket</td><td>Home depot</td><td>05GLHD2</td><td></td></tr><tr><td>Ade Advanced Optics Salinity Refractometer</td><td>Amazon</td><td></td><td>*optional</td></tr><tr><td>Clip board</td><td>Any office supply store or Amazon</td><td></td><td></td></tr><tr><td>Uei Waterproof Digital Thermometer</td><td>Amazon</td><td></td><td>*optional</td></tr><tr><td>Vernier calipers</td><td>Bel-Art</td><td></td><td>Many companies make calipers, however our preferred brand is Bel-Art which can be sourced on Amazon</td></tr></tbody></table>

assessing intertidal populations of the invasive european green crab

Invasive species have caused major disruptions to ecosystems worldwide. The European green crab invaded North America in the 1800s and is considered one of the world&#8217;s 100 worst invaders by the IUCN. Observations of spatiotemporal green crab population dynamics are essential for predicting and managing the ecological and economic impacts of this harmful invasive species. This protocol was developed in an effort to create a standardized method for assessing green crab population dynamics in the rocky intertidal zone of New England and Atlantic Canada. The protocol was designed to be accessible to multiple users including researchers, educators, students, and citizen scientists. Although it was designed for surveying crab populations, this protocol is easy to adapt and could be used for any number of intertidal species. The resulting data collected using this protocol has a wide range of uses, including to inform ecological research, conservation efforts, mitigation strategies, and fishery development, as well as for educational outreach purposes.

In 2019, this protocol was used to conduct monthly intertidal green crab surveys at three locations from May-November (Sandy Point, Yarmouth, ME (43&#176;46&#39;17.92&#34;N, 70&#176; 8&#39;45.52&#34;W), Robinhood Cove, Georgetown, ME (43&#176;48&#39;13.80&#34;N, 69&#176;44&#39;50.97&#34;W), and New Meadows River, West Bath, ME (43&#176;51&#39;17.84&#34;N, 69&#176;51&#39;55.20&#34;W)), and at one location from May-August (Damariscotta River, Walpole, ME (43&#176;56&#39;9.42&#34;N, 69&#176;34&#39;52.75&#34;)). The data col...

Watch this Scientific Journal Video about Assessing Intertidal Populations of the Invasive European Green Crab at JoVE.com

Assessing Intertidal Populations of the Invasive European Green Crab

Understanding spatiotemporal patterns in green crab population dynamics is essential for predicting and managing the ecological and economic impacts of this harmful invasive species. This protocol was developed in an effort to create a standardized method for assessing green crab populations in the rocky intertidal zone of the Northwest Atlantic.

Invasive species have caused major disruptions to ecosystems worldwide. The European green crab invaded North America in the 1800s and is considered one ...

assessing-intertidal-populations-of-the-invasive-european-green-crab

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5.9K Views.  Manomet, Inc.. Understanding spatiotemporal patterns in green crab population dynamics is essential for predicting and managing the ecological and economic impacts of this harmful invasive species. This protocol was developed in an effort to create a standardized method for assessing green crab populations in the rocky intertidal zone of the Northwest Atlantic.

Video: Assessing Intertidal Populations of the Invasive European Green Crab

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol for performing in situ juvenile exposure tests within oligotrophic river catchments over one-month and three-month periods. Two methods (in both modifications) are presented to evaluate the juvenile growth and survival rate. The methods and modifications differ in value for the locality bioindication and each has its benefits as well as limitations. The sandy cage method works with a large set of individuals, but only some of the individuals are measured and the results are evaluated in bulk. In the mesh cage method, the individuals are kept and measured separately, but a low individual number is evaluated. The open water exposure modification is relatively easy to apply; it shows the juvenile growth potential of sites and can also be effective for water toxicity testing. The within-bed exposure modification needs a high workload but is closer to the conditions of a natural juvenile environment and it is better for reporting the real suitability of localities. On the other hand, more replications are needed in this modification due to its high-hyporheic environment variability.

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

In situ bioindications enable determination of the suitability of an environment for endangered mussel species. We describe two methods based on the juvenile exposure of freshwater pearl mussels in cages to oligotrophic river habitats. Both methods are implemented in variants for open water and hyporheic water environments.

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol ...

Methods for Image-based Surveys of Benthic Macroinvertebrates and Their Habitat Exemplified by the Drop Camera Survey for the Atlantic Sea Scallop

Underwater imaging has long been used in the field of marine ecology but decreasing costs of high-resolution cameras and data storage have made the approach more practical than in the past. Image-based surveys allow for initial samples to be revisited and are non-invasive compared to traditional survey methods that typically involve nets or dredges. Protocols for image-based surveys can vary greatly but should be driven by target species behavior and survey objectives. To demonstrate this, we describe our most recent methods for an Atlantic sea scallop (Placopecten magellanicus) drop camera survey to provide a procedural example and representative results. The procedure is divided into three critical steps that include survey design, data collection, and data products. The influence of scallop behavior and the survey goal of providing an independent assessment of the U.S. sea scallop resource on the survey procedure are then discussed in the context of generalizing the method. Overall, the broad applicability and flexibility of the University of Massachusetts Dartmouth School for Marine Science and Technology (SMAST) drop camera survey demonstrates the method could be generalized and applied to a variety of sessile invertebrates or habitat focused research.

Image based surveying is an increasingly practical, non-invasive method to sample the marine environment. We present the protocol of a drop camera survey that estimates the abundance and distribution of the Atlantic sea scallop (Placopecten magellanicus). We discuss how this protocol can be generalized for application to other benthic macroinvertebrates.

Underwater imaging has long been used in the field of marine ecology but decreasing costs of high-resolution cameras and data storage have made the ...

Design and Use of an Apparatus for Quantifying Bivalve Suspension Feeding at Sea

As shellfish aquaculture moves from coastal embayments and estuaries to offshore locations, the need to quantify ecosystem interactions of farmed bivalves (i.e., mussels, oysters, and clams) presents new challenges. Quantitative data on the feeding behavior of suspension-feeding mollusks is necessary to determine important ecosystem interactions of offshore shellfish farms, including their carrying capacity, the competition with the zooplankton community, the availability of trophic resources at different depths, and the deposition to the benthos. The biodeposition method is used to quantify feeding variables in suspension-feeding bivalves in a natural setting and represents a more realistic proxy than laboratory experiments. This method, however, relies upon a stable platform to satisfy the requirements that water flow rates supplied to the shellfish remain constant and the bivalves are undisturbed. A flow-through device and process for using the biodeposition method to quantify the feeding of bivalve mollusks were modified from a land-based format for shipboard use by building a two-dimensional gimbal table around the device. Planimeter data reveal a minimal pitch and yaw of the chambers containing the test shellfish despite boat motion, the flow rates within the chambers remain constant, and operators are able to collect the biodeposits (feces and pseudofeces) with sufficient consistency to obtain accurate measurements of the bivalve clearance, filtration, selection, ingestion, rejection, and absorption at offshore shellfish aquaculture sites.

A flow-through device for using the biodeposition method to quantify filtration and feeding behavior of bivalve mollusks was modified for shipboard use. A two-dimensional gimbal table built around the device isolates the apparatus from boat motion, thereby allowing the accurate quantification of bivalve filtration variables at offshore shellfish aquaculture sites.

As shellfish aquaculture moves from coastal embayments and estuaries to offshore locations, the need to quantify ecosystem interactions of farmed bivalves ...

Data Collection on Marine Litter Ingestion in Sea Turtles and Thresholds for Good Environmental Status

The following protocol is intended to respond to the requirements set by the European Union&#39;s Marine Strategy Framework Directives (MSFD) for the D10C3 Criteria reported in the Commission Decision (EU), related to the amount of litter ingested by marine animals. Standardized methodologies for extracting litter items ingested from dead sea turtles along with guidelines on data analysis are provided. The protocol starts with the collection of dead sea turtles and classification of samples according to the decomposition status. Turtle necropsy must be performed in authorized centers and the protocol described here explains the best procedure for gastrointestinal (GI) tract isolation. The three parts of the GI (esophagus, stomach, intestine) should be separated, opened lengthways and contents filtered using a 1 mm mesh sieve. The article describes the classification and quantification of ingested litter, classifying GI contents into seven different categories of marine litter and two categories of natural remains. The quantity of ingested litter should be reported as total dry mass (weight in grams, with two decimal places) and abundance (number of items). The protocol proposes two possible scenarios to achieve the Good Environmental Status (GES). First: &#34;There should be less than X% of sea turtles having Y g or more plastic in the GI in samples of 50-100 dead turtles from each sub-region&#34;, where Y is the average weight of plastic ingested and X% is the percentage of sea turtles with more weight (in grams) of plastic than Y. The second one, which considers the food remain versus plastic as a proxy of individual health, is: &#34;There should be less than X% of sea turtles having more weight of plastic (in grams) than food remains in the GI in samples of 50-100 dead turtles from each sub-region&#34;.

The protocol focuses on the collection of sea turtle samples, describing all the steps from the animal recovery and necropsy to the classification and quantification of ingested marine litter. Moreover, the representative results show how to use the collected data to elaborate the possible thresholds for Good Environmental Status.

The following protocol is intended to respond to the requirements set by the European Union&#39;s Marine Strategy Framework Directives (MSFD) for the ...

Continuous Noninvasive Measuring of Crayfish Cardiac and Behavioral Activities

A crayfish is a pivotal aquatic organism that serves both as a practical biological model for behavioral and physiological studies of invertebrates and as a useful biological indicator of water quality. Even though crayfish cannot directly specify the substances that cause water quality deterioration, they can immediately (within a few seconds) warn humans of water quality deterioration via acute changes in their cardiac and behavioral activities.
In this study, we present a noninvasive method that is simple enough to be implemented under various conditions due to a combination of simplicity and reliability in one model.
This approach, in which the biological organisms are implemented into environmental evaluation processes, provides a reliable and timely alarm for warning of and preventing acute water deterioration in an ambient environment. Therefore, this noninvasive system based on crayfish physiological and ethological parameter recordings was investigated for the detection of changes in an aquatic environment. This system is now applied at a local brewery for controlling&#160;quality of the water used for beverage production, but it can be used at any water treatment and supply facility for continuous, real-time water quality evaluation and for regular laboratory investigations of crayfish cardiac physiology and behavior.

This article presents a noninvasive biomonitoring system for the continuous recording and analyses of crayfish cardiac and locomotor activities. This system consists of a near-infrared optical sensor, a video-tracking module, and software for evaluating crayfish heartbeats that reflects its physiological condition and characterizes crayfish behavior during heartbeat fluctuations.

A crayfish is a pivotal aquatic organism that serves both as a practical biological model for behavioral and physiological studies of invertebrates and as ...

Behavior

Impedance Pneumography for Minimally Invasive Measurement of Heart Rate in Late Stage Invertebrates

Temperatures in oceans are increasing rapidly as a consequence of widespread changes in world climates. As organismal physiology is heavily influenced by environmental temperature, this has the potential to alter thermal physiological performance in a variety of marine organisms. Using the American lobster (Homarus americanus) as a model organism, this protocol describes the use of impedance pneumography to understand how cardiac performance in late stage invertebrates changes under acute thermal stress. The protocol presents a minimally invasive technique that allows for real-time collection of heart rate during a temperature ramping experiment. Data are easily manipulated to generate an Arrhenius plot that is used to calculate Arrhenius break temperature (ABT), the temperature at which heart rate begins to decline with increasing temperatures. This technique can be used in a variety of late stage invertebrates (i.e., crabs, mussels, or shrimps). Although the protocol focuses solely on the impact of temperature on cardiac performance, it can be modified to understand the potential for additional stressors (e.g., hypoxia or hypercapnia) to interact with temperature to influence physiological performance. Thus, the method has potential for wide-ranging applications to further understand how marine invertebrates respond to acute changes in the environment.

Measuring heart rate during a thermal challenge provides insight into physiological responses of organisms as a consequence of acute environmental change. Using the American lobster (Homarus americanus) as a model organism, this protocol describes the use of impedance pneumography as a relatively noninvasive and nonlethal approach to measure heart rate in late stage invertebrates.

Temperatures in oceans are increasing rapidly as a consequence of widespread changes in world climates. As organismal physiology is heavily influenced by ...

Rapid Testing of Resistance of Timber to Biodegradation by Marine Wood-Boring Crustaceans

Wood-boring invertebrates rapidly destroy marine timbers and wooden coastal infrastructure, causing billions of dollars of damage around the globe every year. As treatments of wood with broad spectrum biocides, such as creosote and chromated copper arsenate (CCA), are now restricted in marine use by legislation, naturally durable timber species and novel preservation methods of wood are required. These methods undergo testing in order to meet regulatory standards, such as the European standard for testing wood preservatives against marine borers, EN 275. Initial investigation of durable timbers species or wood preservative treatments can be achieved quickly and inexpensively through laboratory testing, which offers many advantages over marine field trials that are typically costly, long-term endeavours. Many species of Limnoria (gribble) are marine wood-boring crustaceans. Limnoria are ideal for use in laboratory testing of biodegradation of wood by marine wood-borers, due to the practicality of rearing them in aquaria and the ease of measuring their feeding rates on wood. Herein, we outline a standardizable laboratory test for assessing wood biodegradation using gribble.

This protocol presents a method for assessing the feeding rate of the wood-boring crustacean, Limnoria, by measuring faecal pellet production. This method is designed for use in non-specialist labs and has potential for incorporation into standard testing protocols, to evaluate enhanced wood durability under marine conditions.

Wood-boring invertebrates rapidly destroy marine timbers and wooden coastal infrastructure, causing billions of dollars of damage around the globe every ...

Field Collection and Laboratory Maintenance of Canopy-Forming Giant Kelp to Facilitate Restoration

Canopy-forming kelps are essential foundation species, supporting biodiversity and providing ecosystem services valued at more than USD$500 billion annually. The global decline of giant kelp forests due to climate-driven ecological stressors underscores the need for innovative restoration strategies. An emerging restoration technique known as &#39;green gravel&#39; aims to seed young kelps over large areas without extensive underwater labor and represents a promising restoration tool due to cost-effectiveness and scalability. This video article illustrates a protocol and tools for culturing giant kelp, Macrocystis pyrifera. It also provides a resource for further studies to address the successes and limitations of this method in field settings. We outline field and laboratory-based methods for collecting reproductive tissue, sporulating, inoculating, rearing, maintaining, and monitoring substrates seeded with early life stages using the &#39;green gravel&#39;&#160;technique. The protocol simplifies and centralizes current restoration practices in this field to support researchers, managers, and stakeholders in meeting kelp conservation objectives.

This protocol describes the field collection and regular laboratory maintenance of substrates seeded with canopy-forming giant kelp for use in restoration trials to address the success and limitations of the 'green gravel' technique in field settings.

Canopy-forming kelps are essential foundation species, supporting biodiversity and providing ecosystem services valued at more than USD$500 billion ...

Standardizing a Non-Lethal Method for Characterizing the Reproductive Status and Larval Development of Freshwater Mussels (Bivalvia: Unionida)

Actively monitoring the timing, development, and reproductive patterns of endangered species is critical when managing for population recovery. Freshwater mussels are among the most imperiled organisms in the world, but information about early larval (glochidial) development and brooding periods is still lacking for many species. Previous studies have focused on the complex life history stage when female mussels are ready to parasitize host fish, but few studies have focused on the brooding period and timing of larval development. The protocol described here allows researchers to non-lethally evaluate the state of gravidity for female mussels. The results of this study show that this method does not affect a female mussel&rsquo;s ability to stay gravid or become gravid again after sampling has been performed. The advantage of this method may permit its use on federally threatened or endangered species or other populations of high conservation concern. This protocol can be adapted for use on both preserved or live individuals and was tested on a variety of mussel species. The database provided is a repository for a breadth of information on timing of reproductive habits and will facilitate future freshwater mussel research, conservation, and recovery efforts.

Standardizing a Non-Lethal Method for Characterizing the Reproductive Status and Larval Development of Freshwater Mussels Bivalvia: Unionida

Freshwater mussel conservation is dependent on monitoring reproductive patterns and processes of species. This study standardizes a non-lethal protocol for sampling gill contents, characterizing larval development, and providing a digital repository for data collected. This protocol-database package will be an important tool for mussel researchers in recovery of imperiled species.

Actively monitoring the timing, development, and reproductive patterns of endangered species is critical when managing for population recovery. Freshwater ...

Biology

Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs

Mud crabs (Scylla spp.) are commercially important crustacean species that can be found throughout the Indo-West Pacific region. During culture, the induction of ovarian maturation is important to meet the consumer demand for mature mud crabs and hasten seed production. Eyestalk ablation is an effective tool to enhance ovarian maturation in mud crabs. However, there is no standard protocol for the eyestalk ablation of mud crabs. In this study, two eyestalk ablation techniques are described: cauterization (the use of hot metal to ablate the eyestalk of an anesthetized crab) and surgery (the removal of the eyestalk using surgical scissors). Before eyestalk ablation, sexually mature females (CW &#62; 86 mm) were anesthetized using an ice bag (&#8722;20 &#176;C) with seawater. When the water temperature reached 4 &#176;C, the ice bag was removed from the water. Flowing seawater (ambient temperature: 28 &#176;C) was used for recovery from the anesthesia immediately after eyestalk ablation. Mortality did not occur during or after the process of eyestalk ablation. The eyestalk ablation protocol presented here accelerated the ovarian maturation of the mud crabs.

Two eyestalk ablation protocols (i.e., cauterization and surgery&#160;approaches) were performed on anesthetized female crabs. The eyestalk ablation of mud crabs hastened the ripening of ovaries without decreasing the survival rate.

Mud crabs (Scylla spp.) are commercially important crustacean species that can be found throughout the Indo-West Pacific region. During culture, the ...

Assessing Intertidal Populations of the Invasive European Green Crab

Summary

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Chapters in this video

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

Methods for Image-based Surveys of Benthic Macroinvertebrates and Their Habitat Exemplified by the Drop Camera Survey for the Atlantic Sea Scallop

Design and Use of an Apparatus for Quantifying Bivalve Suspension Feeding at Sea

Data Collection on Marine Litter Ingestion in Sea Turtles and Thresholds for Good Environmental Status

Continuous Noninvasive Measuring of Crayfish Cardiac and Behavioral Activities

Impedance Pneumography for Minimally Invasive Measurement of Heart Rate in Late Stage Invertebrates

Rapid Testing of Resistance of Timber to Biodegradation by Marine Wood-Boring Crustaceans

Field Collection and Laboratory Maintenance of Canopy-Forming Giant Kelp to Facilitate Restoration

Standardizing a Non-Lethal Method for Characterizing the Reproductive Status and Larval Development of Freshwater Mussels (Bivalvia: Unionida)

Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs