#210D-1

[partshnc03]

Maxitrol 210D-1-1 Inch Regulator 10#Maxin 3-8 Inch Wcspring | PartsHnC

Manufacturer Name: Maxitrol

Product Number: 210D-1

OEM Part Number: 210D-1

Product Description: 1" Reg 10#Maxin 3-8"Wcspring

Weight:5.67lbs/2571.87g

The Maxitrol 210D-1 is a reliable 1-inch pressure regulator designed to ensure consistent and accurate air pressure in diverse HVAC applications. Featuring a robust design and a broad pressure range, it proves versatile for various setups.

[hvacparts005]

Maxitrol 210D-1 1/2-1.5 Inch Regulator 10#Maxin3-8 Inch Wcspring | PartsHnC

Manufacturer Name: Maxitrol Product Number: 210D-1 1/2 OEM Part Number: 210D-1 1/2 Product Description: 1.5"Reg 10#Maxin3-8"Wcspring Weight:5.45lbs/2472.08g

The Maxitrol 210D-1 1/2 1.5 Inch Regulator is a precision-engineered component used to regulate gas pressure in HVAC systems. This regulator, which operates at a maximum inlet pressure of 10 pounds.

[hillzerogear]

The DIY Tent Design Process

Everything I’ve shared so far is based on personal opinion and should not be taken as gospel. Now, let's move on to something much more interesting—the DIY tent design process.

I have many friends who are into DIY projects, though most of them are not related to tents. The common reason behind these DIY projects is to fulfill a personal need. Many of us share the same experience: we see designs on the market that don’t quite meet our expectations or the prices are too high for us to afford. Yes, it’s true—it’s about that "personal stash" of money!

Step 1: Collecting Materials (For a Tent)

The materials used in tents are varied and include:

Main fabric: 7D / 10D / 15D / 20D / 30D / 40D / 70D / 210D… mainly nylon

Mesh fabric: 10D / 15D / 20D… polyester or nylon

Aluminum poles: 7.9mm / 8.6mm / 9.0mm / 11mm / 13mm… and also carbon fiber poles

Hardware: WJ / UTX / ITW / YNS

These are just a few examples. Let’s take a simple case for precise description: DIY’ing a pyramid tent based on the HillZero Rheum Nobile 4-6 (https://www.hillzerogear.com/).

Firstly, we should prepare 30D nylon fabric. The amount needed depends on the size of the tent, and we should prepare enough for two sets. This tent requires 22 yards of fabric, so we need to buy 44 yards. Since the first model is often a failure, I always prepare a backup fabric set.

Next, we gather other essentials like hardware, sewing thread, YKK zippers, and aluminum poles.

Step 2: Rough Size Calculations

As mentioned earlier, “All tents are based on basic size calculations. As long as the calculations are accurate, it can be done excellently.”

Tent design can be imagined like building a house. We start with the known dimensions of the tent base (depending on the size of the tent you want to create). For example: Diameter 420cm (165 inches), Height 240cm (94 inches).

We calculate the ridge length of the sides. Whether you use a computer drawing program or do it manually, you can easily determine the measurements. Since it's a regular decagon, each panel is identical.

Step 3: Creating the Model (1:20 Scale)

In this stage, we add elements like zippers, ventilation windows, and guy-line attachment points to the model. The model allows for a visual representation of the tent’s overall structure.

Step 4: Preparing Cardboard for Fabric Cutting

Once the model’s details and measurements are correct, we can create a full-scale pattern. Some may wonder why we need to make this pattern—it's to ensure accurate dimensions for cutting the fabric. Tent fabric is large, and it’s impossible to mark directly on the material. We need to prevent size discrepancies since even a 1cm error can drastically affect the final result.

A few things to note:

Sewing allowances must be added. High-quality tents use double stitching, so we add 2cm extra for seams in the pattern.

Straight lines aren’t always straight. Fabric is soft, and tension can cause warping in the middle, so we need to account for this and adjust accordingly.

Fabric classification is crucial. Despite being a decagon pyramid tent, each piece is different due to factors like fabric width and optimal fabric usage.

Fabric grain matters. Straight grain has no stretch, while diagonal grain has elasticity. This affects how we lay out the pieces to avoid future issues.

Step 5: Sewing and Assembly

Typically, small parts like windows, zippers, and reinforcement patches are sewn first. Then, we move on to assembling the larger body of the tent, piece by piece.

Sewing may sound simple, but it’s an art. If you’re unfamiliar with sewing machines, it can be quite a headache.

Achieving high-quality stitching requires skillful hands, and this task is not for beginners. However, DIY enthusiasts can certainly give it a try, and even if it’s imperfect, it’s your very own creation—something you can proudly use.

Final Thoughts

DIY tent making is an incredibly fun and creative hobby that adds energy to your spare time. Each step of the process has its unique challenges, but with patience and persistence, you’ll learn to solve them. Remember, advice from others is helpful, but only through your own effort and understanding can you overcome these challenges.

Thank you for reading! I’ll continue to share more tent-making processes in the future. The pyramid tent is just a beginner’s project, but to make it truly precise requires meticulous work. If you have any questions, feel free to email me at: nicksan@hillzerogear.com. I’ll do my best to respond!

[veralyndon]

Check out this listing I just added to my Poshmark closet: Hiking Backpack,Camping Backpack,50L Waterproof Hiking Daypack 50l Blue.

[shop4china]

خيمة تخييم أوتوماتيكية مع مظلة متكاملة ، مظلة مقاومة للماء ، خيام للمشي لمسافات طويلة في الهواء الطلق ، نزهة عائلية ، سهلة الفتح ، قابلة للطي ، 5-8 أشخاص

اشتر من الصين مع توصيل مجاني خيمة تخييم أوتوماتيكية مع مظلة متكاملة ، مظلة مقاومة للماء ، خيام للمشي لمسافات طويلة في الهواء الطلق ، نزهة عائلية ، سهلة الفتح ، قابلة للطي ، 5-8 أشخاص

خيمة تخييم أوتوماتيكية مع مظلة متكاملة ، مظلة مقاومة للماء ، خيام للمشي لمسافات طويلة في الهواء الطلق ، نزهة عائلية ، سهلة الفتح ، قابلة للطي ، 5-8 أشخاص

انتباه المشتري من الولايات المتحدة الأمريكية: المناطق التي لا يسلم فيها مستودع الولايات المتحدة البضائع هي: هاواي ، ألاسكا ، بويرتو ريكو ، غوم وغيرها من الأقاليم الأمريكية في الخارج. العنوان العسكري. ولكن يمكنك اختيار الشحن من الصين.

اهتمام المشترين الأسبانية: إذا كان عنوانك يتضمن الرمز البريدي التالي ، يرجى عدم اختيار المستودع الأسبانية. يبدأ الرمز البريدي ��ـ ۱. لا يمكن تسليم المستودع الخارجي. ولكن يمكنك اختيار الشحن من الصين

خيمة أوتوماتيكية سريعة الفتح مع مظلة خيمة تخييم أوتوماتيكية للحماية من الشمس خيمة سداسية محمولة للمشي والتنزه الميزات: 1. خيمة الإعداد الفوري:استمتع براحة الهيكل الأوتوماتيكي بالكامل مع خيمتنا الأوتوماتيكية المفتوحة السريعة التي تتميز بنظام قوس زنبركي متطور للتجميع السريع بدون عناء-ما عليك سوى السحب للفتح فورًا. 2. مواد الحماية من الاشعة فوق البنفسجية:خيمة التخييم الأوتوماتيكية الخاصة بنا مصنوعة من قماش مبطن بالفضة ومقاوم للماء مصنوع من قماش أكسفورد المتين 210 د لتقليل التعرض المباشر لأشعة الشمس ، مما يضمن لك البقاء هادئًا ومحميًا أثناء مغامراتك في الهواء الطلق. 3. التهوية الأمثل:حافظ على راحتك مع تصميم خيمتنا المنبثق الفوري المزدوج ، مما يوفر تدفق هواء واسعًا ودوران لمنع الكفاف ، حتى مع الاستخدام الممتد في المناخات الدافئة. 4. البناء الدائم:المفاصل القابلة للطي للخيمة الخارجية مصنوعة من مادة ABS عالية الجودة ومقاومة للتآكل ، مما يوفر مأوى قوي وطويل الأمد لجميع احتياجات التخييم الخاصة بك. 5. مظلة متعددة الاستخدامات:تتميز هذه الخيمة السداسية المحمولة بغطاء علوي قابل للفصل لإبقائك جافة في المطر ؛ وإزالتها للنظرة على النجوم في ليلة صافية ، بينما توفر النوافذ الجانبية الشبكية الأربعة نسيمًا باردًا وتمنع الحشرات من الخروج لتجربة خارجية هادئة.

المواصفات: الأصل: الصين القارية نسيج الحساب الخارجي: شريط فضي نسيج الحساب: قماش أكسفورد 210d اللون: الجيش الأخضر حجم التمدد: * من * من * من * من * * 54.5 في (3-4 أشخاص) ، * من * من * * * * * من 4 أشخاص (4-6 أشخاص) حجم التخزين: 78*14*14 أو * * 5.46 في (3-4 أشخاص) ، * 16*16*16 أو * 86*6.24 في (4-6 أشخاص) الوزن الصافي: من من ؟ ؟ نوع: فتح سريع التلقائي حالة البناء: لا سرعة البناء عدد الطبقات: طبقة مزدوجة مادة القضيب: الألياف الزجاجية نمط: في الهواء الطلق الموسم المطبق: حساب الفصول الثلاثة مؤشر مقاومة للماء الخارجي: our (شامل)-(حصري) مؤشر مقاومة للماء في الأسفل: our (شامل)-(حصري) هيكل: غرفة نوم واحدة عدد المستخدمين: 3–6 أشخاص

ملاحظة: نظرًا لاختلاف الشاشة وتأثير الضوء ، قد يختلف اللون الفعلي للعنصر قليلاً عن اللون الظهري في الصور. شكرًا لك! يرجى السماح لـ 1-2 بقياس الانحراف بسبب القياس اليدوي.

1 * خيمة أوتوماتيكية بالكامل 1 * حقيبة خيمة مسامير أرضية 8 * * 2 نيلي * القطب 1 * أعلى القماش 6 * حبل الرياح

[excellentpromotionsllc]

Ready, set, go! Our Small Drawstring Backpack is the perfect companion for your on-the-go lifestyle. Compact yet practical, it's ideal for carrying your essentials wherever life takes you.

[africaoutdoors]

Camping tent

 6 Person Hiking Tent Product Description: Our 6 person hiking tent for outdoor activities is made with your convenience in mind, it has enough space to comfortably accommodate up to 6 people with ease which means you can invite more people to enjoy your outdoor party. Features and benefits: 1.Size: 510*244*192cm 2.Fabric: 190T polyester PU coating 3000mm 3.Floor: 210D oxford PU coating…

[bonzatrading]

🚲 Introducing the Ultimate Outdoor Bike Storage Solution!

Keep your bicycles safe, dry, and protected from the elements with our premium Outdoor Bike Covers Storage Shed Tent. Crafted from durable 210D Oxford Thick Waterproof Fabric and reinforced with aluminum alloy brackets, our storage shed ensures maximum durability and weather resistance.

Key Features:

1. High-Quality Material: Made from 210D Oxford Thick Waterproof Fabric, our bike cover shed offers unparalleled protection against rain, snow, UV rays, and dust.

 

2. Sturdy Construction:The aluminum alloy bracket provides robust support, ensuring your bikes or tricycles stay secure even in windy conditions.

 

3. Spacious Design:With enough room to accommodate two bicycles or tricycles, our storage shed offers ample space to keep your outdoor gear organized and clutter-free.

 

4. Easy Access: The zippered door allows for convenient access, making it effortless to retrieve your bikes whenever you're ready for a ride.

5. Versatile Use: Ideal for outdoor storage in your backyard, patio, or garage, our bike shed is perfect for cyclists of all levels.

Why Choose Us?

- Premium Quality: We prioritize quality and durability, ensuring our customers receive a product that stands the test of time.

- Easy Setup:With simple assembly instructions, setting up your bike storage shed is quick and hassle-free.

Don't let your bicycles suffer from exposure to the elements. Invest in our Outdoor Bike Covers Storage Shed Tent today and enjoy peace of mind knowing your bikes are protected year-round!

Learn more

https://amzn.to/49iTFqy

[phukienxebantai]

Tóp 3 mẫu lều nóc ô tô mui cứng bán chạy

Lều nóc ô tô mui cứng là giải pháp hoàn hảo cho những ai yêu thích du lịch, khám phá nhưng muốn tận hưởng sự tiện nghi và thoải mái. Dưới đây là tổng hợp một số mẫu lều nóc ô tô mui cứng phổ biến hiện nay:

1. Lều nóc ô tô ADA mui cứng

Kích thước: 213 x 168 x 102 cm

Trọng lượng: 77 kg

Chất liệu: Vải polyester 600D, khung nhôm

Tính năng: Chống thấm nước, chống tia UV, có cửa sổ thông gió, có mái hiên

Giá bán: 50.000.000 VNĐ

2. Lều iKamper Skycamp 2.0

Kích thước: 200 x 140 x 120 cm

Trọng lượng: 68 kg

Chất liệu: Vải polyester 300D Oxford, khung nhôm

Tính năng: Chống thấm nước, chống tia UV, có cửa sổ thông gió, có mái hiên

Giá bán: 45.000.000 VNĐ

3. Lều Autohome Columbus

Kích thước: 220 x 160 x 130 cm

Trọng lượng: 65 kg

Chất liệu: Vải polyester 210D Oxford, khung nhôm

Tính năng: Chống thấm nước, chống tia UV, có cửa sổ thông gió

Giá bán: 35.000.000 VNĐ

Ba Cách lắp đặt lều nóc ô tô cho xe của bạn:

Đi cùng với 3 cách lắp đặt lều nóc ô tô là 3 kiểu khung lắp đặt cho xe của bạn: Khung lều nóc ô tô

[trendyprojectors]

XHYCPY 16ft Inflatable Movie Screen Review – PROS & CONS – Screen with A...

XHYCPY 16ft Inflatable Movie Screen Outdoor Projector Screen with Air Blower Storage Bag - Front/Rear Projection, Easy Set Up Blow Up Screen for Backyard Movie Night, Theme Parties, Celebrations

Front / Rear Projection - The inflatable movie screen is upgraded to thickened polyester material which support front and rear projection, 160°wide viewing Angle, 16:9 screen ratio, high color reduction. A lot of outdoor movie screens are only setup for front or rear projection, this one gives you both options which is greatly flexibility, you can see clear pictures on any side.

Quick Inflated - High power 110v 250w blower included can blow up this movie screen in 2 minutes and keeps it inflated throughout the show when plugged in（REMEMBER ZIP UP the zipper before inflating）; More importantly, the blower was so hardly noticeable once the movie started, bring you an immersive movie-watching experience.

Easy Set Up - The inflatable projector screen comes with a 210D oxford material free-standing mount frame, removable polyester material screen, tethers, yard stakes, a professional external 250w air blower and a 210D oxford carry bag are included for easy setup and storage; NOTE: The blower need to remain on to keep inflated.

Easy To Carry - Do you want to have a private theater that can be moved? This mega inflatable screen with carry bag is easy to storage and easy to take from location to location. Great for camping adventures, picnics, and outdoor birthday and wedding parties.

Excellent Customer Service - Buy with confidence.1-year manufacturer warranty, hassle free to refund/return/replacement if you meet any questions on our screen. Awesome outdoor movie screen bring your family and friends together for a night of endless fun in your backyard.

[partshnc03]

Maxitrol 210D-1 1/4-1.25 Inch Regulator 10#Maxin 3-8 Inch Spring | PartsHnC

Manufacturer Name: Maxitrol

Product Number: 210D-1 1/4

OEM Part Number: 210D-1 1/4

Product Description: 1.25" Reg 10#Maxin 3-8"Spring

Weight:5.52lbs/2503.83g

The Maxitrol 210D-1 1/4 1.25 Inch Regulator is a critical component for regulating gas pressure in HVAC systems. It is precisely engineered to effectively control gas flow and maintain consistent pressure levels, with a maximum inlet pressure of 10 pounds and a regulation range of 3-8 inches of water column. 

[veralyndon]

Check out this listing I just added to my Poshmark closet: Hiking Backpack,Camping Backpack,50L Waterproof Hiking Daypack 50l Black.

[ogsplendid1]

Thiago Silva is now the oldest outfield player to ever play for Chelsea in the Premier League (37y 210d). The previous oldest was Graham Rix (37 years 203 days), whose appearance also came against Arsenal in a 2-1 victory in May 1995. Master.

[coolllb0]

210D PU Oxford cloth recycled environmental protection fabric

Oxford cloth, also known as Oxford spun, is a kind of fabric with various functions and wide-ranging uses. The main products on the market include: checkered, full stretch, nylon, tiffany and other varieties. Originated in England, the traditional combed cotton fabric named after Oxford University began around 1900.

210D Oxford cloth, has a certain waterproof function, soft, durable and wear-resistant The PU coating can be applied very thickly. It is usually used in combination with the calendering process and used in raincoats, bags, etc.

Characteristics of PU coated Oxford cloth: 1. PVC can improve strength and heat resistance, and has elasticity and ductility, Chemical resistance, anti-ultraviolet, anti-oxidation, etc. 2. Has a certain waterproof function, soft, durable, and wear-resistant,

https://www.amazon.com.au/dp/B094Y2L1JB?ref=myi_title_dp

[roadsride]

5 Best seat covers for dog hair Complete Review & Buying Guide

5 Best seat covers for dog hair Complete Review & Buying Guide

Often people like to keep a dog and they also like to drive in their car with the dog. But have you thought that the hair of the dog falls and the mess spreads to some extent. At such a time, there may be a chance of your car seat being dirty. Then you should take care of your car seat and the dog as well. So that the seat of your car does not become dirty and does not appear scratched. For this you can select a Best seat covers for dog hair.

Types of Dog Car Seat Covers

There are many types of car seat for dog available in the online market which depends on the different shape, size, style, and quality of the material. You can choose which type of car seat cover for dog according to your need.

It should be recognized that the car seat cover not only protects the car seat from dirt but also provides a comfortable and safe ride to the pet.

Here we are talking about 5 types of car seat covers for dog hair. This Surrey Dog Seat Cover are more than one and are considered very good in terms of comfort.

Bench Dog Car Seat Covers

Bench Car Seat Covers considered to be a very good facility and quality car seat cover for dog. This car seat cover designed in such a way that it fits perfectly in the rear of your car. And it seems that this is the design of your car seat and not the top cover.

One of the best advantages of the bench dog seat cover for car is that it fully controls your dog and prevents it from moving forward. And you do not have to face any kind of fear from your dog's paws or the hair of the dog.

Bucket Dog Car Seat Covers

Bucket dog seat covers for dogs are made in a better and better quality. This dog seat cover designed to fit very well for a much larger dog. But if you have small dogs, you want to give them a comfortable ride and want their bones and dirt and hair in one place. So for them you can also look for booster seat option.

No, you cannot think that the bucket seat covers for dogs comes with a single color and single quality and single feature. Rather, different types are made inside it, which is easy to put on the rear seats of the car as well as the front seats of the car.

Cargo Dog Car Seat Covers

Cargo Dog Car Seat Covers considered the best option. If your dog is large size and does not fit in the rear and front seats of your car seat.

Cargo Dog Car Seat Covers is a better car seat cover that protects against dirt and russies. It designed to give complete comfort to your beloved dog. The good thing is that this car seat cover considered very easy to install and clean.

Hammock Dog Car Seat Covers

You should use Hammock Dog Car Seat Covers to get rid of the dirt and hair of the dog. The name of Hammock makes it clear that it is a swing type car seat cover that fits perfectly in your car.

Water proofs are also given inside it which is considered to be a better dog car seat cover to prevent your dog's mess from spreading. Hammock dog seat cover works like a swing on which your dog can swing very easily and can enjoy the journey.

Side Flap Dog Car Seat Covers

Side Flap Car Seat Covers also known as bumper flap. It considered a better dog seat cover for almost every standard vehicles.

Side Flap Dog Car Seat Covers also protects to a large extent from scratches, dust, and dirt. If the dog's dirt spreads inside the car, then you do not have to worry because it is a water resistant.

Applying this car seat cover to your car can easily be cleaned if there is dirt and it is very easy to install back again.

 Why we use Dog Car Seat Covers?

We use car seat covers for dog because we want to protect the dog sitting inside our car and also protect the car seat.

When you put a pet in the car and drive the car, then there are chances of the dog getting dirty and falling on the car seat. And because of this your car seat gets dirty quickly which makes you feel uncomfortable driving. To avoid all these things, we also use the best seat covers for dog hair.

✅ 5 Best seat covers for dog hair

#1. Active pets dog seat cover

Active     Pets introduces the latest in materials technology

Waterproof     barrier between your seats and your dog

Protects     your seats from mud, water and fur, while preventing slip

This     car seat cover will fit any car or SUV!

Provide     maximum protection for your seats

60-second     super EASY and fast installation

Car     seat cover is a joy to clean!

Middle     layer of Oxford 210D with waterproof coating

Using     4 levels of security to keep your pet safe

Learn Full details

#2. URPOWER Dog car Seat Cover

It     is easier for your dog to get in or out of car

Protect     your car door from scratch and hair

Available     for most cars, trucks, automotive and SUVs

Heavy-duty     oxford fabric and comfortable PP cotton mat

Totally     keep your seat from any dirt, liquid, scratches, hair & fur. Etc.

Excellent     size of 60" W x 64" L will perfectly protect your car

Built-in     nonslip backing

Seat     anchors to prevent seat cover from sliding around

Built-in     Velcro openings for your Seatbelts

Easy     to install with quick release clips

Easy     to clean with a damp cloth or vacuum

Learn Full details

  #3. Plush Paws premium convertible rear pet seat cover

A     seat liner, 2 seat belt clips

2     harnesses help to keep pets safe in the car

This     car seat cover for dog is made from durable, waterproof, and     tear-resistant canvas.

Anchors,     flaps, and straps make installation quick and easy

Perfect     for puppy rides

It     helps anxious dogs relax during long rides in cars, trucks, or SUVs

This     car sear cover provide good protection, dog safety, and gear for     adventures.

Learn Full details

  #4. Vailge bench dog car seat cover

Excellent     size of 56" Wide x 60" Length are larger

Protect     your car from scratches or mud

It     designed for most backseats of STANDARD cars, trucks & SUVs

Easily     convertible between hammock or standard bench coverage

Side     flaps can protect your car door from scratch, hair

Car     seat cover have two waterproof layers

Built-in     nonslip backing

Seat     anchors to prevent seat cover from sliding around

Easy     to install with quick release clips

It's     also easy to clean

Machine     Washable

Learn Full details

  #5. Honest Luxury Quilted Dog Car Seat Covers

Excellent     design with Side Flap

This     dog seat cover can protect your car seat from scratch, hair, smell and     dirt

keep     your pet safe

Passenger     and pets can sit in the back seat

Excellent     Size

The     quality material is 100% waterproof

Non     Slip backing and seat anchors to prevent the seat cover from sliding back     and forth

You     can just clean with damp cloth or vacuum cleaner

Learn Full details

 Conclusion: Best Seat Covers for Dog Hair

Car seat cover is a better thing for all those who are dog lovers. And that people prefer sit dog in his car.

Therefore, we have mentioned here the 5 best seat covers for dog hair, which you must buy. All these car seat covers for dog hair are of good quality and follow all the features that we just mentioned.

[juniperpublishersoceanography]

The Effect of Salinity Acclimation on the Upper Thermal Tolerance Threshold of the European Green Crab

Abstract

Fluctuations in salinity and temperature, among other varying environmental conditions, are stressors in estuaries and may work together to alter the physiological response of organisms that inhabit such environments. Laboratory assessments that investigate how animals respond to multiple environmental stressors can provide an ecological framework for understanding physiological performance across varying conditions. In this study, European green crabs, Carcinus maenas, were collected from Seadrift Lagoon, California, USA (37°54′27.82″N, 122°40′19.56″W) and were lab-acclimated at three different salinity concentrations typical of many estuaries: 15, 25, and 35 PSU at 12 °C (± 1 °C). After acclimation, crabs from each salinity treatment experienced a temperature ramp of 2 °C every 30min until they reached their critical thermal maxima (CTmax). Crabs held at 15 PSU acclimation treatment died at significantly lower temperatures than those acclimated to 25 PSU, demonstrating that the upper thermal tolerance of C. maenas is decreased at lower salinities. Hence, crabs in the northeast Pacific, which are limited to estuarine and brackish waters by marine predators, may be physiologically limited from further expanding their southern range boundary due to the effect of increased temperature on physiological performance. This work took place in March, 2013 and highlights the importance of examining the effect of multiple stressors to understanding what factors may limit or enhance range shifts.

Keywords: Carcinus maenas; Multi-stressor; Salinity acclimation; Thermal tolerance; Abiotic resistance; Invasive species

Introduction

Ecophysiological research has historically focused on altering one abiotic variable at a time to measure the physiological response to that variable. However, examining how multiple stressors affect organisms provides a more holistic view into factors that govern distribution and abundance of species [1-3]. The intersection of fresh and salt water, coupled with thermal fluctuations typical of estuaries can affect physiological performance, leading to geographic distribution limitations of estuarine organisms Sokolova et al. [4]. Additionally, along the west coast of North America, the estuarine distribution of Carcinus maenas has been attributed to predation by a larger, aggressive native crab Hunt & Yamada [5].

Owing to their broad thermal and salinity tolerance, C. maenas has successfully invaded coastal habitats of four continents, including the west coast of North America [6-8]. In addition, C. maenas can survive and reproduce in a wide range of salinity concentrations because they are proficient osmoregulators [9]. Nagaraj [6] found that salinity had little to no effect on developmental rates of C. maenas; however, zoeae kept in high salinity treatments (25 and 35ppt) had the greatest survival rates at the lowest experimental temperature, ~10 °C [6]. While these studies are informative, they do not necessarily reflect the dynamic abiotic environment that C. maenas inhabits.

In the eastern Pacific, C. maenas is preyed upon by native crabs, limiting their habitat use of the open coast, consequently forcing C. maenas to occupy areas with greater temperature and salinity fluctuations [5]. As such, C. maenas populations generally reside in upper estuaries, which are characteristically warmer and less salinated [5]. For C. maenas specifically, exposure to lower salinities leads to increased oxygen demand (i.e. increased anaerobic metabolic rate) as a means to offset the concomitant increase in hemolymph pH, which in turn affects the hemolymph’s O2 affinity [10]. The variable salinity concentration of estuaries in conjunction with their often warmer conditions [5] may combine to limit the ability of C. maenas to mount robust heat stress response, thus lowering the upper thermal tolerance, despite it being a euryhaline hyperosmotic regulator. Ionic stress combined with heat stress has been investigated in larval C. maenas; however, the effect of variations in salinity concentrations on adult crab upper thermal tolerance has yet to be investigated. To better understand how variations in salinity affect the upper thermal tolerance of adult crabs, animals were acclimated to three different salinity concentrations common to estuaries and then were subject to acute heat stress. Given that C. maenas is an osmoregulator, such that decreased salinity increases metabolic demand, we hypothesized that a reduction in salinity would circumvent the ability of C. maenas to mount a robust response to heat stress, thus reducing organismal thermotolerance.

Methods

Sampling, maintenance, and salinity treatments

Male and female Carcinus maenas were collected from Seadrift Lagoon, Stinson Beach, California, USA in August 2012, and transported to Portland State University, Oregon, USA. The crabs were temperature acclimated at 12 °C (± 1 °C) and 30 PSU for approximately 210d prior to the salinity acclimation phase. Three groups were then formed via random selection and acclimated to 15, 25, or 35 PSU, encompassing the salinity conditions where they are typically found (~10-35 PSU) [11] for 56d. Each salinity-controlled treatment group was held in a separate, self-sustaining, recirculating-water, temperaturecontrolled aquarium table system in artificial sea water (Instant Ocean) treated with 20mL of a nitrogen reducer (AmQuel) per approximately 151.42L of water, when nitrogen was high. System salinity was held within ± 1 PSU of the target salinity concentration for each treatment group by thrice weekly salinity measurements and additions of deionized water as needed to maintain the respective salt concentrations. The crabs were fed a medley of squid, fish, and mussels ad libitum, once per week.

Heat ramping

Members of the C. maenas sample population (n = 15 per treatment) were randomly selected from each salinity treatment and placed in recirculating and continually aerated water bath (Lauda RM6 MGW) filled with aquarium water from their acclimation tank. The bath was then ramped up by 2 °C every 30min, beginning from a base temperature of 12 °C ± 1 °C Kelley et al. [7]. The temperature at which each crab expired was monitored with a Vernier thermometer probe (± 0.1 °C) and recorded. Critical thermal maximum (here after CTmax), a standard measure of temperature-related animal death, was determined via a set of criteria verified by physical examination [7]. If the specimen was unresponsive to manipulation and could not right itself, it was held just below the surface of the water and examined for signs of respiration, i.e., water movement via the activity of the scaphognathite Crothers [12]. If cessation of respiration lasted for longer than 30s, the specimen was considered physiologically deceased and was removed from the water bath. Upon each crab’s death, we removed the specimen and recorded its treatment group, sex, temperature at death, and carapace width. Heat ramping continued until all of the experimental animals expired.

Statistics

To determine that the assumptions of normality and homoschedasticity were not violated, the Kolmogorov-Smirnov Goodness-of-Fit Test (P = 0.57) and Bartlett’s test for equal variance (P > 0.1) were used (Graphpad Prism) prior to analysis. Analysis of Covariance (ANCOVA), followed by Tukey’s Multiple Comparison Test were employed to determine whether salinity (fixed) and crab size (continuous covariate) affected the upper thermal tolerance of the crabs (Minitab 17). To further explore the relationship between carapace width (CW) and CTmax, a linear regression was used (Graphpad Prism).

Results

The three salinity treatments differed in their mean CTmax values (Figure 1, Table 1, ANCOVA, F(2,42) = 4.16, P = 0.02). The mean differences in CTmax between 15 PSU and 25 PSU, 15 PSU and 35 PSU, and 25 PSU and 35 PSU were -2.6, -1.3, and 1.3 °C, respectively. Tukey’s Multiple Comparison Test revealed a significant difference between the 15 PSU and the 25 PSU samples: the average CTmax of the 15 PSU sample (32.5 °C ± 0.6 °C) was significantly lower than that of the 25 PSU sample (35.0 °C ± 0.46 °C, Figure 1). The 35 PSU treatment was intermediate, having an average CTmax of 33.7°C ± 0.6, and did not significantly differ from the CTmax values of the other two salinity treatments. CW also significantly affected the upper thermal tolerance threshold, with lower CTmax for larger crabs (Figure 2: r2 = 0.2, y=-0.1*x + 41; ANCOVA. F(2,41); P = 0.008).

Discussion

We found that adult crabs that were acclimated to low salinity concentrations showed greater susceptibility to rising temperature. Crabs acclimated to lower salinity had a significantly lower CTmax than crabs acclimated to 25 PSU, supporting our initial hypothesis that lower salinity environments can negatively affect the upper thermal tolerance of adult Carcinus maenas. This finding was in accordance with a study that examined the effect of salinity acclimation on thermotolerance and larval development distribution of larval C. maenas Nagaraj [6]. Similarly, in another study, temperature interacted with salinity, together affecting larval development duration and attachment of the barnacle Balanus trigonus Thiyagarajan et al. [13]. Variations in salinity and temperature significantly modified the development of Nile tilapia, Oreochromis niloticus, but the interaction of the two variables modified development in unpredictable ways, with growth rates peaking at different temperatures as salinity changed Likongwe et al. [14]. A decrease in salinity concentration was also shown to significantly limit the range of temperatures tolerable by the bivalves Mercenaria mercenaria and Crassostrea virginica, for both survival and larval development Davis and Calabrese [15].

Our CTmax data suggest that after acclimation to a low salinity (15 PSU), temperature tolerance decreased significantly, offering an additional abiotic variable that may further limit their distribution. Hence, a large expansion south to warmer waters along the western North American coast seems unlikely This observed decrease in temperature tolerance implies that although C. maenas is capable of tolerating low salinities, it is metabolically taxing for them and could synergistically alter their ability to physically cope with thermal stress. Southward expansion of east coast  C. maenas populations has been documented to be limited by native crab species found in estuaries De Rivera et al. [16], our data suggest that salinity and temperature in concert with predation together limit southward expansion. Together these multiple stressors may determine the potential for future range expansion of  C. maenas.

A recent study found a significant relationship between environmental temperature and body size across this population of C. maenas, with larger crabs occupying areas of cooler temperatures, a phenomenon known as the temperaturesize rule for ectotherms Kelley et al. [17]. Here, we have shown that larger crabs tend to have a lower overall thermal tolerance threshold than smaller crabs (Figure 2). This study provides further evidence supporting the temperature-size rule in that large crabs that inhabit warmer, hyposaline water are more susceptible to heat stress, such that temperature acts as a selection force against larger body size.

Our study’s findings add to the body of literature supporting the conclusion that multiple stressors combine synergistically and may affect geographic range expansion and possibly overall success; however, the exact effects and synergistic relationship differ across species Todgham et al. [18], Crain et al. [1], McBryan et al. [19], Todgham and Stillman [3]. Together these studies, and others, suggest that the interaction between salinity concentration and temperature on aquatic life is not purely additive, and that more research is needed on multiple environmental stressors acting in one system, especially to predict the geographic distribution of species as their ranges shift due to climate change or biological invasion. Because of overwhelming evidence of climate change, it is important to consider the implications of inevitable further rise in temperature and changing estuarine salinities on native and non-native marine species in the near future Kelley [20], Sorte et al. [21]. The predicted change in riverine input could alter salinity and temperature along with pH, and could be modeled to understand potential future distributions. Life at low salinity levels and high temperatures becomes increasingly difficult for native and invasive species and can cause northward range expansion of C. maenas Kelley et al. [3], Hunt and Yamada [5]. It is important to understand the many abiotic factors can affect C. maenas distribution in order to predict future range expansions and possible ecological and economic effects of a non-native species on native marine animals and delicately balanced ecosystems.

Conclusion

This study documents that other environmental factors influence the upper thermal tolerance of the invasive Carcinus maenas, the European green crab. Understanding the role that dynamic environments play in regulating the physiological tolerances of invasive organisms is critical to gaining insight regarding the ecology of biological invasions. This research underscores the importance of, and the need to conduct studies that investigate the interplay of multiple environmental stressors on the physiology of non-native species.

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