From Detritus to Delicacy: Using Harpacticoid Copepods for Natural Nutrient Cycling

Pretty much nobody wants their marine aquarium to be covered with filth and green slime. Yet, mulm and benthic microalgae show up (at least in some amount) in just about every system. This is normal to some degree. However, anything more than a patch here or there can be seen as a symptom of problems or deficiencies that are inherent in the maintenance regime, tank set-up or ecology of the aquarium system itself.

These issues might include:
•Overfeeding.
•Overstocking (especially with fish).
•Poor water flow or the presence or “dead areas” in the aquascape.
•Inadequate filtration (mechanical, chemical and/or biological).
•Inadequate water exchange.
•A lack of detritivorous and herbivorous organisms.

Most of these individual issues can compound to affect (either beneficially or adversely) the others. For example, moderate stocking and judicious feeding can greatly reduce the input of biological waste products. Powerful filtration and water movement can significantly ease the removal of these wastes. Finally, the presence of a large and comprehensive clean-up crew can (1) mop up whatever solid waste products might remain as well as (2) control the bacterial and algal biofouling that might result from them.

Clean-up crews are necessarily comprised of a diverse group of detritivores and herbivores. This typically includes relatively larger organisms such as snails and hermit crabs. But this can also (and should also) include relatively smaller scavenging organisms such as copepods. There are a few of big reasons for this. For one, tiny pods attack both detritus and nuisance algae. They do so from the ground up, preventing major accumulations/growths before sizeable numbers of larger scavengers are needed. Perhaps most importantly, pods play a critical role in establishing a truly efficient nutrient cycle. Why? Because in addition to serving at the front lines of your clean-up crew, they provide a highly nutritious and self-supplying food for many of your aquarium inhabitants!

Copepods are The Critical Link

Copepods can be found in virtually every natural marine ecosystem. And, their impact on these ecosystems is generally quite strong. By feeding on particulate organic matter, protozoans and (especially) microalgae—and then in turn being consumed by higher animals such as fish and corals—copepods facilitate the transfer of food energy from lower to higher levels of the food chain.

And copepods are not just naturally abundant; they have a very impressive food value. They have a high protein content (44-52%). They are rich in color-enhancing pigments (e.g. astaxanthin). Though specific content of fatty acids relates directly to the amount/types of algae in their diet, pods tend to be a very rich source of HUFAs. They even contain enzymes that can greatly promote digestion for those animals that eat them. Moreover, their exoskeletons provide an important source of dietary roughage. Find copepods for sale online to ensure a healthy marine ecosystem.

Getting Around

Harpacticoid copepods (such as Tigriopus) are particularly useful to marine aquarists. This is because they tend to undergo both planktonic stages (when young) and benthic stages (when mature). The planktonic juveniles (i.e. nauplii) strip the water column of excessive phytoplankton, helping to keep the water clear. They are heavily preyed upon by filter-feeding zooplanktivores (i.e. corals). The benthic adults scour rock, sand and tank panels clean. They are heavily preyed upon by small reef fishes such as mandarins.

Harpacticoids usually enjoy a much more varied diet than other types of copepods. Even so, some (e.g. Tisbe) seem to be able to consistently maintain an ideal ratio of fatty acids regardless of the content of their diet. This is because they are capable of elongating and desaturating the shorter chain n-6 and n-3 fatty acids (18:2n-6, 18:3n-3, etc.) into the long-chain EFAs 20:4n-6, 20:5n-3 and 22:6n-3. Thus, they are themselves a wholesome, balanced food even when grown on nutritionally bereft items such as detritus.

Because harpacticoid copepods (especially nearshore species) are adapted to sudden, broad swings of environmental quality, they are comparatively easy to keep for long periods of time in aquaria. In fact, if pampered just a little, they can form stable, permanent populations that just keep on giving. Perhaps the most important factor here is feeding of nauplii.

A captive population of copepods might reach a point where densities become limited due to low densities of appropriate phytoplankton. Here, regardless of the amount of detritus and biofilms that is available for adults, juveniles suffer from a lack of suspended microalgal food sources. In many cases, this is simply because the food in the water column ran out before the food on the bottom did. The solution? Restore the balance by adding select species of phytoplankton! In addition to benefiting many corals and clams, these desirable forms of phytoplankton will greatly promote the survival of young pods, which leads to more adult pods, which leads to better clean-up on the tank bottom.

Nature’s way is best

Is it really that simple? For the most part, yes! The first step, of course, is seeding (and periodically re-seeding) with lots of harpacticoid pods. The best live products (1) combine a smart mix of species and (2) include individuals of all life stages. A mixed-species live product (for example, one containing both Tisbe and Tigriopus) provides a more well-rounded clean-up capability and also provides a wider size range of foods for their many predators. An all-life-stage live product (that is, one containing ages from larvae to adult) is not only immediately useful as a food for all sorts of fish and invertebrates, but also can speed up the process of seeding (i.e. establishing a permanent resident population).

Poseidon’s Feast meets both of the above criteria. Like Poseidon’s Feast, 5280 Pods includes Tisbe and Tigriopus; 5280 Pods additionally includes the cyclopoid copepod Apocyclops which (being planktonic as adults) will be appreciated by zooplanktivorous fishes such as seahorses, anthias and many small wrasses. Especially with the regular addition of quality live phytoplankton such as OceanMagik, both Tisbe and Tigriopus will flourish, promoting reef-clean rocks and tank panels while providing a natural and nutritious live food. Any remaining sediments are enriched by photoheterotrophic bacteria (such as those in PNS Probio™); this naturally transfers vitamins and carotenoids up the food chain (bacteria>pods>fish). What better way to deal with aquarium wastes than to turn them into a wholesome meal?